ETH Price: $2,521.93 (-0.62%)

Transaction Decoder

Block:
20038650 at Jun-07-2024 08:06:59 AM +UTC
Transaction Fee:
0.003806991942764736 ETH $9.60
Gas Used:
267,152 Gas / 14.250284268 Gwei

Emitted Events:

138 ComposableStablePool.Transfer( from=0x0000000000000000000000000000000000000000, to=ProtocolFeesCollector, value=11988208519713418 )
139 ComposableStablePool.Transfer( from=0x0000000000000000000000000000000000000000, to=ProtocolFeesCollector, value=66530243964587 )
140 ComposableStablePool.Transfer( from=[Sender] 0x583a893f1d8f18c7421ed58a96be559c70cd32c0, to=0x0000000000000000000000000000000000000000, value=998833884130510210 )
141 TransparentUpgradeableProxy.0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef( 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef, 0x000000000000000000000000ba12222222228d8ba445958a75a0704d566bf2c8, 0x000000000000000000000000583a893f1d8f18c7421ed58a96be559c70cd32c0, 0000000000000000000000000000000000000000000000000deeef2ccbc17db1 )
142 Vault.PoolBalanceChanged( poolId=848A5564158D84B8A8FB68AB5D004FAE11619A5400000000000000000000066A, liquidityProvider=[Sender] 0x583a893f1d8f18c7421ed58a96be559c70cd32c0, tokens=[0x848a5564158d84b8A8fb68ab5D004Fae11619A54, 0xbf5495Efe5DB9ce00f80364C8B423567e58d2110, 0xCd5fE23C85820F7B72D0926FC9b05b43E359b7ee, 0xFAe103DC9cf190eD75350761e95403b7b8aFa6c0], deltas=[0, -1004002742626254257, 0, 0], protocolFeeAmounts=[0, 0, 0, 0] )

Account State Difference:

  Address   Before After State Difference Code
(Titan Builder)
7.979080679799669946 Eth7.979108546860514858 Eth0.000027867060844912
0x583A893F...c70Cd32C0
2.000020939815694167 Eth
Nonce: 91
1.996213947872929431 Eth
Nonce: 92
0.003806991942764736
0x848a5564...e11619A54
0xBA122222...d566BF2C8
(Balancer: Vault)
0xbf5495Ef...7e58d2110

Execution Trace

Vault.exitPool( poolId=848A5564158D84B8A8FB68AB5D004FAE11619A5400000000000000000000066A, sender=0x583A893F1d8F18c7421ED58a96Be559c70Cd32C0, recipient=0x583A893F1d8F18c7421ED58a96Be559c70Cd32C0, request=[{name:assets, type:address[], order:1, indexed:false, value:[0x848a5564158d84b8A8fb68ab5D004Fae11619A54, 0xbf5495Efe5DB9ce00f80364C8B423567e58d2110, 0xCd5fE23C85820F7B72D0926FC9b05b43E359b7ee, 0xFAe103DC9cf190eD75350761e95403b7b8aFa6c0], valueString:[0x848a5564158d84b8A8fb68ab5D004Fae11619A54, 0xbf5495Efe5DB9ce00f80364C8B423567e58d2110, 0xCd5fE23C85820F7B72D0926FC9b05b43E359b7ee, 0xFAe103DC9cf190eD75350761e95403b7b8aFa6c0]}, {name:minAmountsOut, type:uint256[], order:2, indexed:false, value:[0, 998986075223212980, 0, 0], valueString:[0, 998986075223212980, 0, 0]}, {name:userData, type:bytes, order:3, indexed:false, value:0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000DDC9220253905820000000000000000000000000000000000000000000000000000000000000000, valueString:0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000DDC9220253905820000000000000000000000000000000000000000000000000000000000000000}, {name:toInternalBalance, type:bool, order:4, indexed:false, value:false, valueString:False}] )
  • ProtocolFeesCollector.STATICCALL( )
  • ComposableStablePool.onExitPool( poolId=848A5564158D84B8A8FB68AB5D004FAE11619A5400000000000000000000066A, sender=0x583A893F1d8F18c7421ED58a96Be559c70Cd32C0, recipient=0x583A893F1d8F18c7421ED58a96Be559c70Cd32C0, balances=[2596148429268010297148408564842634, 2387290882979167042247, 457646850047481348140, 722768671688844082219], lastChangeBlock=20038209, protocolSwapFeePercentage=500000000000000000, userData=0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000DDC9220253905820000000000000000000000000000000000000000000000000000000000000000 ) => ( [0, 1004002742626254257, 0, 0], [0, 0, 0, 0] )
  • TransparentUpgradeableProxy.a9059cbb( )
    • EzEthToken.transfer( to=0x583A893F1d8F18c7421ED58a96Be559c70Cd32C0, amount=1004002742626254257 ) => ( True )
      exitPool[PoolBalances (ln:3547)]
      File 1 of 5: Vault
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "./interfaces/IAuthorizer.sol";
      import "./interfaces/IWETH.sol";
      import "./VaultAuthorization.sol";
      import "./FlashLoans.sol";
      import "./Swaps.sol";
      /**
       * @dev The `Vault` is Balancer V2's core contract. A single instance of it exists for the entire network, and it is the
       * entity used to interact with Pools by Liquidity Providers who join and exit them, Traders who swap, and Asset
       * Managers who withdraw and deposit tokens.
       *
       * The `Vault`'s source code is split among a number of sub-contracts, with the goal of improving readability and making
       * understanding the system easier. Most sub-contracts have been marked as `abstract` to explicitly indicate that only
       * the full `Vault` is meant to be deployed.
       *
       * Roughly speaking, these are the contents of each sub-contract:
       *
       *  - `AssetManagers`: Pool token Asset Manager registry, and Asset Manager interactions.
       *  - `Fees`: set and compute protocol fees.
       *  - `FlashLoans`: flash loan transfers and fees.
       *  - `PoolBalances`: Pool joins and exits.
       *  - `PoolRegistry`: Pool registration, ID management, and basic queries.
       *  - `PoolTokens`: Pool token registration and registration, and balance queries.
       *  - `Swaps`: Pool swaps.
       *  - `UserBalance`: manage user balances (Internal Balance operations and external balance transfers)
       *  - `VaultAuthorization`: access control, relayers and signature validation.
       *
       * Additionally, the different Pool specializations are handled by the `GeneralPoolsBalance`,
       * `MinimalSwapInfoPoolsBalance` and `TwoTokenPoolsBalance` sub-contracts, which in turn make use of the
       * `BalanceAllocation` library.
       *
       * The most important goal of the `Vault` is to make token swaps use as little gas as possible. This is reflected in a
       * multitude of design decisions, from minor things like the format used to store Pool IDs, to major features such as
       * the different Pool specialization settings.
       *
       * Finally, the large number of tasks carried out by the Vault means its bytecode is very large, close to exceeding
       * the contract size limit imposed by EIP 170 (https://eips.ethereum.org/EIPS/eip-170). Manual tuning of the source code
       * was required to improve code generation and bring the bytecode size below this limit. This includes extensive
       * utilization of `internal` functions (particularly inside modifiers), usage of named return arguments, dedicated
       * storage access methods, dynamic revert reason generation, and usage of inline assembly, to name a few.
       */
      contract Vault is VaultAuthorization, FlashLoans, Swaps {
          constructor(
              IAuthorizer authorizer,
              IWETH weth,
              uint256 pauseWindowDuration,
              uint256 bufferPeriodDuration
          ) VaultAuthorization(authorizer) AssetHelpers(weth) TemporarilyPausable(pauseWindowDuration, bufferPeriodDuration) {
              // solhint-disable-previous-line no-empty-blocks
          }
          function setPaused(bool paused) external override nonReentrant authenticate {
              _setPaused(paused);
          }
          // solhint-disable-next-line func-name-mixedcase
          function WETH() external view override returns (IWETH) {
              return _WETH();
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      interface IAuthorizer {
          /**
           * @dev Returns true if `account` can perform the action described by `actionId` in the contract `where`.
           */
          function canPerform(
              bytes32 actionId,
              address account,
              address where
          ) external view returns (bool);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "../../lib/openzeppelin/IERC20.sol";
      /**
       * @dev Interface for the WETH token contract used internally for wrapping and unwrapping, to support
       * sending and receiving ETH in joins, swaps, and internal balance deposits and withdrawals.
       */
      interface IWETH is IERC20 {
          function deposit() external payable;
          function withdraw(uint256 amount) external;
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../lib/helpers/BalancerErrors.sol";
      import "../lib/helpers/Authentication.sol";
      import "../lib/helpers/TemporarilyPausable.sol";
      import "../lib/helpers/BalancerErrors.sol";
      import "../lib/helpers/SignaturesValidator.sol";
      import "../lib/openzeppelin/ReentrancyGuard.sol";
      import "./interfaces/IVault.sol";
      import "./interfaces/IAuthorizer.sol";
      /**
       * @dev Manages access control of Vault permissioned functions by relying on the Authorizer and signature validation.
       *
       * Additionally handles relayer access and approval.
       */
      abstract contract VaultAuthorization is
          IVault,
          ReentrancyGuard,
          Authentication,
          SignaturesValidator,
          TemporarilyPausable
      {
          // Ideally, we'd store the type hashes as immutable state variables to avoid computing the hash at runtime, but
          // unfortunately immutable variables cannot be used in assembly, so we just keep the precomputed hashes instead.
          // _JOIN_TYPE_HASH = keccak256("JoinPool(bytes calldata,address sender,uint256 nonce,uint256 deadline)");
          bytes32 private constant _JOIN_TYPE_HASH = 0x3f7b71252bd19113ff48c19c6e004a9bcfcca320a0d74d58e85877cbd7dcae58;
          // _EXIT_TYPE_HASH = keccak256("ExitPool(bytes calldata,address sender,uint256 nonce,uint256 deadline)");
          bytes32 private constant _EXIT_TYPE_HASH = 0x8bbc57f66ea936902f50a71ce12b92c43f3c5340bb40c27c4e90ab84eeae3353;
          // _SWAP_TYPE_HASH = keccak256("Swap(bytes calldata,address sender,uint256 nonce,uint256 deadline)");
          bytes32 private constant _SWAP_TYPE_HASH = 0xe192dcbc143b1e244ad73b813fd3c097b832ad260a157340b4e5e5beda067abe;
          // _BATCH_SWAP_TYPE_HASH = keccak256("BatchSwap(bytes calldata,address sender,uint256 nonce,uint256 deadline)");
          bytes32 private constant _BATCH_SWAP_TYPE_HASH = 0x9bfc43a4d98313c6766986ffd7c916c7481566d9f224c6819af0a53388aced3a;
          // _SET_RELAYER_TYPE_HASH =
          //     keccak256("SetRelayerApproval(bytes calldata,address sender,uint256 nonce,uint256 deadline)");
          bytes32
              private constant _SET_RELAYER_TYPE_HASH = 0xa3f865aa351e51cfeb40f5178d1564bb629fe9030b83caf6361d1baaf5b90b5a;
          IAuthorizer private _authorizer;
          mapping(address => mapping(address => bool)) private _approvedRelayers;
          /**
           * @dev Reverts unless `user` is the caller, or the caller is approved by the Authorizer to call this function (that
           * is, it is a relayer for that function), and either:
           *  a) `user` approved the caller as a relayer (via `setRelayerApproval`), or
           *  b) a valid signature from them was appended to the calldata.
           *
           * Should only be applied to external functions.
           */
          modifier authenticateFor(address user) {
              _authenticateFor(user);
              _;
          }
          constructor(IAuthorizer authorizer)
              // The Vault is a singleton, so it simply uses its own address to disambiguate action identifiers.
              Authentication(bytes32(uint256(address(this))))
              SignaturesValidator("Balancer V2 Vault")
          {
              _setAuthorizer(authorizer);
          }
          function setAuthorizer(IAuthorizer newAuthorizer) external override nonReentrant authenticate {
              _setAuthorizer(newAuthorizer);
          }
          function _setAuthorizer(IAuthorizer newAuthorizer) private {
              emit AuthorizerChanged(newAuthorizer);
              _authorizer = newAuthorizer;
          }
          function getAuthorizer() external view override returns (IAuthorizer) {
              return _authorizer;
          }
          function setRelayerApproval(
              address sender,
              address relayer,
              bool approved
          ) external override nonReentrant whenNotPaused authenticateFor(sender) {
              _approvedRelayers[sender][relayer] = approved;
              emit RelayerApprovalChanged(relayer, sender, approved);
          }
          function hasApprovedRelayer(address user, address relayer) external view override returns (bool) {
              return _hasApprovedRelayer(user, relayer);
          }
          /**
           * @dev Reverts unless `user` is the caller, or the caller is approved by the Authorizer to call the entry point
           * function (that is, it is a relayer for that function) and either:
           *  a) `user` approved the caller as a relayer (via `setRelayerApproval`), or
           *  b) a valid signature from them was appended to the calldata.
           */
          function _authenticateFor(address user) internal {
              if (msg.sender != user) {
                  // In this context, 'permission to call a function' means 'being a relayer for a function'.
                  _authenticateCaller();
                  // Being a relayer is not sufficient: `user` must have also approved the caller either via
                  // `setRelayerApproval`, or by providing a signature appended to the calldata.
                  if (!_hasApprovedRelayer(user, msg.sender)) {
                      _validateSignature(user, Errors.USER_DOESNT_ALLOW_RELAYER);
                  }
              }
          }
          /**
           * @dev Returns true if `user` approved `relayer` to act as a relayer for them.
           */
          function _hasApprovedRelayer(address user, address relayer) internal view returns (bool) {
              return _approvedRelayers[user][relayer];
          }
          function _canPerform(bytes32 actionId, address user) internal view override returns (bool) {
              // Access control is delegated to the Authorizer.
              return _authorizer.canPerform(actionId, user, address(this));
          }
          function _typeHash() internal pure override returns (bytes32 hash) {
              // This is a simple switch-case statement, trivially written in Solidity by chaining else-if statements, but the
              // assembly implementation results in much denser bytecode.
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  // The function selector is located at the first 4 bytes of calldata. We copy the first full calldata
                  // 256 word, and then perform a logical shift to the right, moving the selector to the least significant
                  // 4 bytes.
                  let selector := shr(224, calldataload(0))
                  // With the selector in the least significant 4 bytes, we can use 4 byte literals with leading zeros,
                  // resulting in dense bytecode (PUSH4 opcodes).
                  switch selector
                      case 0xb95cac28 {
                          hash := _JOIN_TYPE_HASH
                      }
                      case 0x8bdb3913 {
                          hash := _EXIT_TYPE_HASH
                      }
                      case 0x52bbbe29 {
                          hash := _SWAP_TYPE_HASH
                      }
                      case 0x945bcec9 {
                          hash := _BATCH_SWAP_TYPE_HASH
                      }
                      case 0xfa6e671d {
                          hash := _SET_RELAYER_TYPE_HASH
                      }
                      default {
                          hash := 0x0000000000000000000000000000000000000000000000000000000000000000
                      }
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      // This flash loan provider was based on the Aave protocol's open source
      // implementation and terminology and interfaces are intentionally kept
      // similar
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../lib/helpers/BalancerErrors.sol";
      import "../lib/openzeppelin/IERC20.sol";
      import "../lib/openzeppelin/ReentrancyGuard.sol";
      import "../lib/openzeppelin/SafeERC20.sol";
      import "./Fees.sol";
      import "./interfaces/IFlashLoanRecipient.sol";
      /**
       * @dev Handles Flash Loans through the Vault. Calls the `receiveFlashLoan` hook on the flash loan recipient
       * contract, which implements the `IFlashLoanRecipient` interface.
       */
      abstract contract FlashLoans is Fees, ReentrancyGuard, TemporarilyPausable {
          using SafeERC20 for IERC20;
          function flashLoan(
              IFlashLoanRecipient recipient,
              IERC20[] memory tokens,
              uint256[] memory amounts,
              bytes memory userData
          ) external override nonReentrant whenNotPaused {
              InputHelpers.ensureInputLengthMatch(tokens.length, amounts.length);
              uint256[] memory feeAmounts = new uint256[](tokens.length);
              uint256[] memory preLoanBalances = new uint256[](tokens.length);
              // Used to ensure `tokens` is sorted in ascending order, which ensures token uniqueness.
              IERC20 previousToken = IERC20(0);
              for (uint256 i = 0; i < tokens.length; ++i) {
                  IERC20 token = tokens[i];
                  uint256 amount = amounts[i];
                  _require(token > previousToken, token == IERC20(0) ? Errors.ZERO_TOKEN : Errors.UNSORTED_TOKENS);
                  previousToken = token;
                  preLoanBalances[i] = token.balanceOf(address(this));
                  feeAmounts[i] = _calculateFlashLoanFeeAmount(amount);
                  _require(preLoanBalances[i] >= amount, Errors.INSUFFICIENT_FLASH_LOAN_BALANCE);
                  token.safeTransfer(address(recipient), amount);
              }
              recipient.receiveFlashLoan(tokens, amounts, feeAmounts, userData);
              for (uint256 i = 0; i < tokens.length; ++i) {
                  IERC20 token = tokens[i];
                  uint256 preLoanBalance = preLoanBalances[i];
                  // Checking for loan repayment first (without accounting for fees) makes for simpler debugging, and results
                  // in more accurate revert reasons if the flash loan protocol fee percentage is zero.
                  uint256 postLoanBalance = token.balanceOf(address(this));
                  _require(postLoanBalance >= preLoanBalance, Errors.INVALID_POST_LOAN_BALANCE);
                  // No need for checked arithmetic since we know the loan was fully repaid.
                  uint256 receivedFeeAmount = postLoanBalance - preLoanBalance;
                  _require(receivedFeeAmount >= feeAmounts[i], Errors.INSUFFICIENT_FLASH_LOAN_FEE_AMOUNT);
                  _payFeeAmount(token, receivedFeeAmount);
                  emit FlashLoan(recipient, token, amounts[i], receivedFeeAmount);
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../lib/math/Math.sol";
      import "../lib/helpers/BalancerErrors.sol";
      import "../lib/helpers/InputHelpers.sol";
      import "../lib/openzeppelin/EnumerableMap.sol";
      import "../lib/openzeppelin/EnumerableSet.sol";
      import "../lib/openzeppelin/IERC20.sol";
      import "../lib/openzeppelin/ReentrancyGuard.sol";
      import "../lib/openzeppelin/SafeCast.sol";
      import "../lib/openzeppelin/SafeERC20.sol";
      import "./PoolBalances.sol";
      import "./interfaces/IPoolSwapStructs.sol";
      import "./interfaces/IGeneralPool.sol";
      import "./interfaces/IMinimalSwapInfoPool.sol";
      import "./balances/BalanceAllocation.sol";
      /**
       * Implements the Vault's high-level swap functionality.
       *
       * Users can swap tokens with Pools by calling the `swap` and `batchSwap` functions. They need not trust the Pool
       * contracts to do this: all security checks are made by the Vault.
       *
       * The `swap` function executes a single swap, while `batchSwap` can perform multiple swaps in sequence.
       * In each individual swap, tokens of one kind are sent from the sender to the Pool (this is the 'token in'),
       * and tokens of another kind are sent from the Pool to the recipient in exchange (this is the 'token out').
       * More complex swaps, such as one 'token in' to multiple tokens out can be achieved by batching together
       * individual swaps.
       */
      abstract contract Swaps is ReentrancyGuard, PoolBalances {
          using SafeERC20 for IERC20;
          using EnumerableSet for EnumerableSet.AddressSet;
          using EnumerableMap for EnumerableMap.IERC20ToBytes32Map;
          using Math for int256;
          using Math for uint256;
          using SafeCast for uint256;
          using BalanceAllocation for bytes32;
          function swap(
              SingleSwap memory singleSwap,
              FundManagement memory funds,
              uint256 limit,
              uint256 deadline
          )
              external
              payable
              override
              nonReentrant
              whenNotPaused
              authenticateFor(funds.sender)
              returns (uint256 amountCalculated)
          {
              // The deadline is timestamp-based: it should not be relied upon for sub-minute accuracy.
              // solhint-disable-next-line not-rely-on-time
              _require(block.timestamp <= deadline, Errors.SWAP_DEADLINE);
              // This revert reason is for consistency with `batchSwap`: an equivalent `swap` performed using that function
              // would result in this error.
              _require(singleSwap.amount > 0, Errors.UNKNOWN_AMOUNT_IN_FIRST_SWAP);
              IERC20 tokenIn = _translateToIERC20(singleSwap.assetIn);
              IERC20 tokenOut = _translateToIERC20(singleSwap.assetOut);
              _require(tokenIn != tokenOut, Errors.CANNOT_SWAP_SAME_TOKEN);
              // Initializing each struct field one-by-one uses less gas than setting all at once.
              IPoolSwapStructs.SwapRequest memory poolRequest;
              poolRequest.poolId = singleSwap.poolId;
              poolRequest.kind = singleSwap.kind;
              poolRequest.tokenIn = tokenIn;
              poolRequest.tokenOut = tokenOut;
              poolRequest.amount = singleSwap.amount;
              poolRequest.userData = singleSwap.userData;
              poolRequest.from = funds.sender;
              poolRequest.to = funds.recipient;
              // The lastChangeBlock field is left uninitialized.
              uint256 amountIn;
              uint256 amountOut;
              (amountCalculated, amountIn, amountOut) = _swapWithPool(poolRequest);
              _require(singleSwap.kind == SwapKind.GIVEN_IN ? amountOut >= limit : amountIn <= limit, Errors.SWAP_LIMIT);
              _receiveAsset(singleSwap.assetIn, amountIn, funds.sender, funds.fromInternalBalance);
              _sendAsset(singleSwap.assetOut, amountOut, funds.recipient, funds.toInternalBalance);
              // If the asset in is ETH, then `amountIn` ETH was wrapped into WETH.
              _handleRemainingEth(_isETH(singleSwap.assetIn) ? amountIn : 0);
          }
          function batchSwap(
              SwapKind kind,
              BatchSwapStep[] memory swaps,
              IAsset[] memory assets,
              FundManagement memory funds,
              int256[] memory limits,
              uint256 deadline
          )
              external
              payable
              override
              nonReentrant
              whenNotPaused
              authenticateFor(funds.sender)
              returns (int256[] memory assetDeltas)
          {
              // The deadline is timestamp-based: it should not be relied upon for sub-minute accuracy.
              // solhint-disable-next-line not-rely-on-time
              _require(block.timestamp <= deadline, Errors.SWAP_DEADLINE);
              InputHelpers.ensureInputLengthMatch(assets.length, limits.length);
              // Perform the swaps, updating the Pool token balances and computing the net Vault asset deltas.
              assetDeltas = _swapWithPools(swaps, assets, funds, kind);
              // Process asset deltas, by either transferring assets from the sender (for positive deltas) or to the recipient
              // (for negative deltas).
              uint256 wrappedEth = 0;
              for (uint256 i = 0; i < assets.length; ++i) {
                  IAsset asset = assets[i];
                  int256 delta = assetDeltas[i];
                  _require(delta <= limits[i], Errors.SWAP_LIMIT);
                  if (delta > 0) {
                      uint256 toReceive = uint256(delta);
                      _receiveAsset(asset, toReceive, funds.sender, funds.fromInternalBalance);
                      if (_isETH(asset)) {
                          wrappedEth = wrappedEth.add(toReceive);
                      }
                  } else if (delta < 0) {
                      uint256 toSend = uint256(-delta);
                      _sendAsset(asset, toSend, funds.recipient, funds.toInternalBalance);
                  }
              }
              // Handle any used and remaining ETH.
              _handleRemainingEth(wrappedEth);
          }
          // For `_swapWithPools` to handle both 'given in' and 'given out' swaps, it internally tracks the 'given' amount
          // (supplied by the caller), and the 'calculated' amount (returned by the Pool in response to the swap request).
          /**
           * @dev Given the two swap tokens and the swap kind, returns which one is the 'given' token (the token whose
           * amount is supplied by the caller).
           */
          function _tokenGiven(
              SwapKind kind,
              IERC20 tokenIn,
              IERC20 tokenOut
          ) private pure returns (IERC20) {
              return kind == SwapKind.GIVEN_IN ? tokenIn : tokenOut;
          }
          /**
           * @dev Given the two swap tokens and the swap kind, returns which one is the 'calculated' token (the token whose
           * amount is calculated by the Pool).
           */
          function _tokenCalculated(
              SwapKind kind,
              IERC20 tokenIn,
              IERC20 tokenOut
          ) private pure returns (IERC20) {
              return kind == SwapKind.GIVEN_IN ? tokenOut : tokenIn;
          }
          /**
           * @dev Returns an ordered pair (amountIn, amountOut) given the 'given' and 'calculated' amounts, and the swap kind.
           */
          function _getAmounts(
              SwapKind kind,
              uint256 amountGiven,
              uint256 amountCalculated
          ) private pure returns (uint256 amountIn, uint256 amountOut) {
              if (kind == SwapKind.GIVEN_IN) {
                  (amountIn, amountOut) = (amountGiven, amountCalculated);
              } else {
                  // SwapKind.GIVEN_OUT
                  (amountIn, amountOut) = (amountCalculated, amountGiven);
              }
          }
          /**
           * @dev Performs all `swaps`, calling swap hooks on the Pool contracts and updating their balances. Does not cause
           * any transfer of tokens - instead it returns the net Vault token deltas: positive if the Vault should receive
           * tokens, and negative if it should send them.
           */
          function _swapWithPools(
              BatchSwapStep[] memory swaps,
              IAsset[] memory assets,
              FundManagement memory funds,
              SwapKind kind
          ) private returns (int256[] memory assetDeltas) {
              assetDeltas = new int256[](assets.length);
              // These variables could be declared inside the loop, but that causes the compiler to allocate memory on each
              // loop iteration, increasing gas costs.
              BatchSwapStep memory batchSwapStep;
              IPoolSwapStructs.SwapRequest memory poolRequest;
              // These store data about the previous swap here to implement multihop logic across swaps.
              IERC20 previousTokenCalculated;
              uint256 previousAmountCalculated;
              for (uint256 i = 0; i < swaps.length; ++i) {
                  batchSwapStep = swaps[i];
                  bool withinBounds = batchSwapStep.assetInIndex < assets.length &&
                      batchSwapStep.assetOutIndex < assets.length;
                  _require(withinBounds, Errors.OUT_OF_BOUNDS);
                  IERC20 tokenIn = _translateToIERC20(assets[batchSwapStep.assetInIndex]);
                  IERC20 tokenOut = _translateToIERC20(assets[batchSwapStep.assetOutIndex]);
                  _require(tokenIn != tokenOut, Errors.CANNOT_SWAP_SAME_TOKEN);
                  // Sentinel value for multihop logic
                  if (batchSwapStep.amount == 0) {
                      // When the amount given is zero, we use the calculated amount for the previous swap, as long as the
                      // current swap's given token is the previous calculated token. This makes it possible to swap a
                      // given amount of token A for token B, and then use the resulting token B amount to swap for token C.
                      _require(i > 0, Errors.UNKNOWN_AMOUNT_IN_FIRST_SWAP);
                      bool usingPreviousToken = previousTokenCalculated == _tokenGiven(kind, tokenIn, tokenOut);
                      _require(usingPreviousToken, Errors.MALCONSTRUCTED_MULTIHOP_SWAP);
                      batchSwapStep.amount = previousAmountCalculated;
                  }
                  // Initializing each struct field one-by-one uses less gas than setting all at once
                  poolRequest.poolId = batchSwapStep.poolId;
                  poolRequest.kind = kind;
                  poolRequest.tokenIn = tokenIn;
                  poolRequest.tokenOut = tokenOut;
                  poolRequest.amount = batchSwapStep.amount;
                  poolRequest.userData = batchSwapStep.userData;
                  poolRequest.from = funds.sender;
                  poolRequest.to = funds.recipient;
                  // The lastChangeBlock field is left uninitialized
                  uint256 amountIn;
                  uint256 amountOut;
                  (previousAmountCalculated, amountIn, amountOut) = _swapWithPool(poolRequest);
                  previousTokenCalculated = _tokenCalculated(kind, tokenIn, tokenOut);
                  // Accumulate Vault deltas across swaps
                  assetDeltas[batchSwapStep.assetInIndex] = assetDeltas[batchSwapStep.assetInIndex].add(amountIn.toInt256());
                  assetDeltas[batchSwapStep.assetOutIndex] = assetDeltas[batchSwapStep.assetOutIndex].sub(
                      amountOut.toInt256()
                  );
              }
          }
          /**
           * @dev Performs a swap according to the parameters specified in `request`, calling the Pool's contract hook and
           * updating the Pool's balance.
           *
           * Returns the amount of tokens going into or out of the Vault as a result of this swap, depending on the swap kind.
           */
          function _swapWithPool(IPoolSwapStructs.SwapRequest memory request)
              private
              returns (
                  uint256 amountCalculated,
                  uint256 amountIn,
                  uint256 amountOut
              )
          {
              // Get the calculated amount from the Pool and update its balances
              address pool = _getPoolAddress(request.poolId);
              PoolSpecialization specialization = _getPoolSpecialization(request.poolId);
              if (specialization == PoolSpecialization.TWO_TOKEN) {
                  amountCalculated = _processTwoTokenPoolSwapRequest(request, IMinimalSwapInfoPool(pool));
              } else if (specialization == PoolSpecialization.MINIMAL_SWAP_INFO) {
                  amountCalculated = _processMinimalSwapInfoPoolSwapRequest(request, IMinimalSwapInfoPool(pool));
              } else {
                  // PoolSpecialization.GENERAL
                  amountCalculated = _processGeneralPoolSwapRequest(request, IGeneralPool(pool));
              }
              (amountIn, amountOut) = _getAmounts(request.kind, request.amount, amountCalculated);
              emit Swap(request.poolId, request.tokenIn, request.tokenOut, amountIn, amountOut);
          }
          function _processTwoTokenPoolSwapRequest(IPoolSwapStructs.SwapRequest memory request, IMinimalSwapInfoPool pool)
              private
              returns (uint256 amountCalculated)
          {
              // For gas efficiency reasons, this function uses low-level knowledge of how Two Token Pool balances are
              // stored internally, instead of using getters and setters for all operations.
              (
                  bytes32 tokenABalance,
                  bytes32 tokenBBalance,
                  TwoTokenPoolBalances storage poolBalances
              ) = _getTwoTokenPoolSharedBalances(request.poolId, request.tokenIn, request.tokenOut);
              // We have the two Pool balances, but we don't know which one is 'token in' or 'token out'.
              bytes32 tokenInBalance;
              bytes32 tokenOutBalance;
              // In Two Token Pools, token A has a smaller address than token B
              if (request.tokenIn < request.tokenOut) {
                  // in is A, out is B
                  tokenInBalance = tokenABalance;
                  tokenOutBalance = tokenBBalance;
              } else {
                  // in is B, out is A
                  tokenOutBalance = tokenABalance;
                  tokenInBalance = tokenBBalance;
              }
              // Perform the swap request and compute the new balances for 'token in' and 'token out' after the swap
              (tokenInBalance, tokenOutBalance, amountCalculated) = _callMinimalSwapInfoPoolOnSwapHook(
                  request,
                  pool,
                  tokenInBalance,
                  tokenOutBalance
              );
              // We check the token ordering again to create the new shared cash packed struct
              poolBalances.sharedCash = request.tokenIn < request.tokenOut
                  ? BalanceAllocation.toSharedCash(tokenInBalance, tokenOutBalance) // in is A, out is B
                  : BalanceAllocation.toSharedCash(tokenOutBalance, tokenInBalance); // in is B, out is A
          }
          function _processMinimalSwapInfoPoolSwapRequest(
              IPoolSwapStructs.SwapRequest memory request,
              IMinimalSwapInfoPool pool
          ) private returns (uint256 amountCalculated) {
              bytes32 tokenInBalance = _getMinimalSwapInfoPoolBalance(request.poolId, request.tokenIn);
              bytes32 tokenOutBalance = _getMinimalSwapInfoPoolBalance(request.poolId, request.tokenOut);
              // Perform the swap request and compute the new balances for 'token in' and 'token out' after the swap
              (tokenInBalance, tokenOutBalance, amountCalculated) = _callMinimalSwapInfoPoolOnSwapHook(
                  request,
                  pool,
                  tokenInBalance,
                  tokenOutBalance
              );
              _minimalSwapInfoPoolsBalances[request.poolId][request.tokenIn] = tokenInBalance;
              _minimalSwapInfoPoolsBalances[request.poolId][request.tokenOut] = tokenOutBalance;
          }
          /**
           * @dev Calls the onSwap hook for a Pool that implements IMinimalSwapInfoPool: both Minimal Swap Info and Two Token
           * Pools do this.
           */
          function _callMinimalSwapInfoPoolOnSwapHook(
              IPoolSwapStructs.SwapRequest memory request,
              IMinimalSwapInfoPool pool,
              bytes32 tokenInBalance,
              bytes32 tokenOutBalance
          )
              internal
              returns (
                  bytes32 newTokenInBalance,
                  bytes32 newTokenOutBalance,
                  uint256 amountCalculated
              )
          {
              uint256 tokenInTotal = tokenInBalance.total();
              uint256 tokenOutTotal = tokenOutBalance.total();
              request.lastChangeBlock = Math.max(tokenInBalance.lastChangeBlock(), tokenOutBalance.lastChangeBlock());
              // Perform the swap request callback, and compute the new balances for 'token in' and 'token out' after the swap
              amountCalculated = pool.onSwap(request, tokenInTotal, tokenOutTotal);
              (uint256 amountIn, uint256 amountOut) = _getAmounts(request.kind, request.amount, amountCalculated);
              newTokenInBalance = tokenInBalance.increaseCash(amountIn);
              newTokenOutBalance = tokenOutBalance.decreaseCash(amountOut);
          }
          function _processGeneralPoolSwapRequest(IPoolSwapStructs.SwapRequest memory request, IGeneralPool pool)
              private
              returns (uint256 amountCalculated)
          {
              bytes32 tokenInBalance;
              bytes32 tokenOutBalance;
              // We access both token indexes without checking existence, because we will do it manually immediately after.
              EnumerableMap.IERC20ToBytes32Map storage poolBalances = _generalPoolsBalances[request.poolId];
              uint256 indexIn = poolBalances.unchecked_indexOf(request.tokenIn);
              uint256 indexOut = poolBalances.unchecked_indexOf(request.tokenOut);
              if (indexIn == 0 || indexOut == 0) {
                  // The tokens might not be registered because the Pool itself is not registered. We check this to provide a
                  // more accurate revert reason.
                  _ensureRegisteredPool(request.poolId);
                  _revert(Errors.TOKEN_NOT_REGISTERED);
              }
              // EnumerableMap stores indices *plus one* to use the zero index as a sentinel value - because these are valid,
              // we can undo this.
              indexIn -= 1;
              indexOut -= 1;
              uint256 tokenAmount = poolBalances.length();
              uint256[] memory currentBalances = new uint256[](tokenAmount);
              request.lastChangeBlock = 0;
              for (uint256 i = 0; i < tokenAmount; i++) {
                  // Because the iteration is bounded by `tokenAmount`, and no tokens are registered or deregistered here, we
                  // know `i` is a valid token index and can use `unchecked_valueAt` to save storage reads.
                  bytes32 balance = poolBalances.unchecked_valueAt(i);
                  currentBalances[i] = balance.total();
                  request.lastChangeBlock = Math.max(request.lastChangeBlock, balance.lastChangeBlock());
                  if (i == indexIn) {
                      tokenInBalance = balance;
                  } else if (i == indexOut) {
                      tokenOutBalance = balance;
                  }
              }
              // Perform the swap request callback and compute the new balances for 'token in' and 'token out' after the swap
              amountCalculated = pool.onSwap(request, currentBalances, indexIn, indexOut);
              (uint256 amountIn, uint256 amountOut) = _getAmounts(request.kind, request.amount, amountCalculated);
              tokenInBalance = tokenInBalance.increaseCash(amountIn);
              tokenOutBalance = tokenOutBalance.decreaseCash(amountOut);
              // Because no tokens were registered or deregistered between now or when we retrieved the indexes for
              // 'token in' and 'token out', we can use `unchecked_setAt` to save storage reads.
              poolBalances.unchecked_setAt(indexIn, tokenInBalance);
              poolBalances.unchecked_setAt(indexOut, tokenOutBalance);
          }
          // This function is not marked as `nonReentrant` because the underlying mechanism relies on reentrancy
          function queryBatchSwap(
              SwapKind kind,
              BatchSwapStep[] memory swaps,
              IAsset[] memory assets,
              FundManagement memory funds
          ) external override returns (int256[] memory) {
              // In order to accurately 'simulate' swaps, this function actually does perform the swaps, including calling the
              // Pool hooks and updating balances in storage. However, once it computes the final Vault Deltas, it
              // reverts unconditionally, returning this array as the revert data.
              //
              // By wrapping this reverting call, we can decode the deltas 'returned' and return them as a normal Solidity
              // function would. The only caveat is the function becomes non-view, but off-chain clients can still call it
              // via eth_call to get the expected result.
              //
              // This technique was inspired by the work from the Gnosis team in the Gnosis Safe contract:
              // https://github.com/gnosis/safe-contracts/blob/v1.2.0/contracts/GnosisSafe.sol#L265
              //
              // Most of this function is implemented using inline assembly, as the actual work it needs to do is not
              // significant, and Solidity is not particularly well-suited to generate this behavior, resulting in a large
              // amount of generated bytecode.
              if (msg.sender != address(this)) {
                  // We perform an external call to ourselves, forwarding the same calldata. In this call, the else clause of
                  // the preceding if statement will be executed instead.
                  // solhint-disable-next-line avoid-low-level-calls
                  (bool success, ) = address(this).call(msg.data);
                  // solhint-disable-next-line no-inline-assembly
                  assembly {
                      // This call should always revert to decode the actual asset deltas from the revert reason
                      switch success
                          case 0 {
                              // Note we are manually writing the memory slot 0. We can safely overwrite whatever is
                              // stored there as we take full control of the execution and then immediately return.
                              // We copy the first 4 bytes to check if it matches with the expected signature, otherwise
                              // there was another revert reason and we should forward it.
                              returndatacopy(0, 0, 0x04)
                              let error := and(mload(0), 0xffffffff00000000000000000000000000000000000000000000000000000000)
                              // If the first 4 bytes don't match with the expected signature, we forward the revert reason.
                              if eq(eq(error, 0xfa61cc1200000000000000000000000000000000000000000000000000000000), 0) {
                                  returndatacopy(0, 0, returndatasize())
                                  revert(0, returndatasize())
                              }
                              // The returndata contains the signature, followed by the raw memory representation of an array:
                              // length + data. We need to return an ABI-encoded representation of this array.
                              // An ABI-encoded array contains an additional field when compared to its raw memory
                              // representation: an offset to the location of the length. The offset itself is 32 bytes long,
                              // so the smallest value we  can use is 32 for the data to be located immediately after it.
                              mstore(0, 32)
                              // We now copy the raw memory array from returndata into memory. Since the offset takes up 32
                              // bytes, we start copying at address 0x20. We also get rid of the error signature, which takes
                              // the first four bytes of returndata.
                              let size := sub(returndatasize(), 0x04)
                              returndatacopy(0x20, 0x04, size)
                              // We finally return the ABI-encoded array, which has a total length equal to that of the array
                              // (returndata), plus the 32 bytes for the offset.
                              return(0, add(size, 32))
                          }
                          default {
                              // This call should always revert, but we fail nonetheless if that didn't happen
                              invalid()
                          }
                  }
              } else {
                  int256[] memory deltas = _swapWithPools(swaps, assets, funds, kind);
                  // solhint-disable-next-line no-inline-assembly
                  assembly {
                      // We will return a raw representation of the array in memory, which is composed of a 32 byte length,
                      // followed by the 32 byte int256 values. Because revert expects a size in bytes, we multiply the array
                      // length (stored at `deltas`) by 32.
                      let size := mul(mload(deltas), 32)
                      // We send one extra value for the error signature "QueryError(int256[])" which is 0xfa61cc12.
                      // We store it in the previous slot to the `deltas` array. We know there will be at least one available
                      // slot due to how the memory scratch space works.
                      // We can safely overwrite whatever is stored in this slot as we will revert immediately after that.
                      mstore(sub(deltas, 0x20), 0x00000000000000000000000000000000000000000000000000000000fa61cc12)
                      let start := sub(deltas, 0x04)
                      // When copying from `deltas` into returndata, we copy an additional 36 bytes to also return the array's
                      // length and the error signature.
                      revert(start, add(size, 36))
                  }
              }
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      /**
       * @dev Interface of the ERC20 standard as defined in the EIP.
       */
      interface IERC20 {
          /**
           * @dev Returns the amount of tokens in existence.
           */
          function totalSupply() external view returns (uint256);
          /**
           * @dev Returns the amount of tokens owned by `account`.
           */
          function balanceOf(address account) external view returns (uint256);
          /**
           * @dev Moves `amount` tokens from the caller's account to `recipient`.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * Emits a {Transfer} event.
           */
          function transfer(address recipient, uint256 amount) external returns (bool);
          /**
           * @dev Returns the remaining number of tokens that `spender` will be
           * allowed to spend on behalf of `owner` through {transferFrom}. This is
           * zero by default.
           *
           * This value changes when {approve} or {transferFrom} are called.
           */
          function allowance(address owner, address spender) external view returns (uint256);
          /**
           * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * IMPORTANT: Beware that changing an allowance with this method brings the risk
           * that someone may use both the old and the new allowance by unfortunate
           * transaction ordering. One possible solution to mitigate this race
           * condition is to first reduce the spender's allowance to 0 and set the
           * desired value afterwards:
           * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
           *
           * Emits an {Approval} event.
           */
          function approve(address spender, uint256 amount) external returns (bool);
          /**
           * @dev Moves `amount` tokens from `sender` to `recipient` using the
           * allowance mechanism. `amount` is then deducted from the caller's
           * allowance.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * Emits a {Transfer} event.
           */
          function transferFrom(
              address sender,
              address recipient,
              uint256 amount
          ) external returns (bool);
          /**
           * @dev Emitted when `value` tokens are moved from one account (`from`) to
           * another (`to`).
           *
           * Note that `value` may be zero.
           */
          event Transfer(address indexed from, address indexed to, uint256 value);
          /**
           * @dev Emitted when the allowance of a `spender` for an `owner` is set by
           * a call to {approve}. `value` is the new allowance.
           */
          event Approval(address indexed owner, address indexed spender, uint256 value);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      // solhint-disable
      /**
       * @dev Reverts if `condition` is false, with a revert reason containing `errorCode`. Only codes up to 999 are
       * supported.
       */
      function _require(bool condition, uint256 errorCode) pure {
          if (!condition) _revert(errorCode);
      }
      /**
       * @dev Reverts with a revert reason containing `errorCode`. Only codes up to 999 are supported.
       */
      function _revert(uint256 errorCode) pure {
          // We're going to dynamically create a revert string based on the error code, with the following format:
          // 'BAL#{errorCode}'
          // where the code is left-padded with zeroes to three digits (so they range from 000 to 999).
          //
          // We don't have revert strings embedded in the contract to save bytecode size: it takes much less space to store a
          // number (8 to 16 bits) than the individual string characters.
          //
          // The dynamic string creation algorithm that follows could be implemented in Solidity, but assembly allows for a
          // much denser implementation, again saving bytecode size. Given this function unconditionally reverts, this is a
          // safe place to rely on it without worrying about how its usage might affect e.g. memory contents.
          assembly {
              // First, we need to compute the ASCII representation of the error code. We assume that it is in the 0-999
              // range, so we only need to convert three digits. To convert the digits to ASCII, we add 0x30, the value for
              // the '0' character.
              let units := add(mod(errorCode, 10), 0x30)
              errorCode := div(errorCode, 10)
              let tenths := add(mod(errorCode, 10), 0x30)
              errorCode := div(errorCode, 10)
              let hundreds := add(mod(errorCode, 10), 0x30)
              // With the individual characters, we can now construct the full string. The "BAL#" part is a known constant
              // (0x42414c23): we simply shift this by 24 (to provide space for the 3 bytes of the error code), and add the
              // characters to it, each shifted by a multiple of 8.
              // The revert reason is then shifted left by 200 bits (256 minus the length of the string, 7 characters * 8 bits
              // per character = 56) to locate it in the most significant part of the 256 slot (the beginning of a byte
              // array).
              let revertReason := shl(200, add(0x42414c23000000, add(add(units, shl(8, tenths)), shl(16, hundreds))))
              // We can now encode the reason in memory, which can be safely overwritten as we're about to revert. The encoded
              // message will have the following layout:
              // [ revert reason identifier ] [ string location offset ] [ string length ] [ string contents ]
              // The Solidity revert reason identifier is 0x08c739a0, the function selector of the Error(string) function. We
              // also write zeroes to the next 28 bytes of memory, but those are about to be overwritten.
              mstore(0x0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
              // Next is the offset to the location of the string, which will be placed immediately after (20 bytes away).
              mstore(0x04, 0x0000000000000000000000000000000000000000000000000000000000000020)
              // The string length is fixed: 7 characters.
              mstore(0x24, 7)
              // Finally, the string itself is stored.
              mstore(0x44, revertReason)
              // Even if the string is only 7 bytes long, we need to return a full 32 byte slot containing it. The length of
              // the encoded message is therefore 4 + 32 + 32 + 32 = 100.
              revert(0, 100)
          }
      }
      library Errors {
          // Math
          uint256 internal constant ADD_OVERFLOW = 0;
          uint256 internal constant SUB_OVERFLOW = 1;
          uint256 internal constant SUB_UNDERFLOW = 2;
          uint256 internal constant MUL_OVERFLOW = 3;
          uint256 internal constant ZERO_DIVISION = 4;
          uint256 internal constant DIV_INTERNAL = 5;
          uint256 internal constant X_OUT_OF_BOUNDS = 6;
          uint256 internal constant Y_OUT_OF_BOUNDS = 7;
          uint256 internal constant PRODUCT_OUT_OF_BOUNDS = 8;
          uint256 internal constant INVALID_EXPONENT = 9;
          // Input
          uint256 internal constant OUT_OF_BOUNDS = 100;
          uint256 internal constant UNSORTED_ARRAY = 101;
          uint256 internal constant UNSORTED_TOKENS = 102;
          uint256 internal constant INPUT_LENGTH_MISMATCH = 103;
          uint256 internal constant ZERO_TOKEN = 104;
          // Shared pools
          uint256 internal constant MIN_TOKENS = 200;
          uint256 internal constant MAX_TOKENS = 201;
          uint256 internal constant MAX_SWAP_FEE_PERCENTAGE = 202;
          uint256 internal constant MIN_SWAP_FEE_PERCENTAGE = 203;
          uint256 internal constant MINIMUM_BPT = 204;
          uint256 internal constant CALLER_NOT_VAULT = 205;
          uint256 internal constant UNINITIALIZED = 206;
          uint256 internal constant BPT_IN_MAX_AMOUNT = 207;
          uint256 internal constant BPT_OUT_MIN_AMOUNT = 208;
          uint256 internal constant EXPIRED_PERMIT = 209;
          // Pools
          uint256 internal constant MIN_AMP = 300;
          uint256 internal constant MAX_AMP = 301;
          uint256 internal constant MIN_WEIGHT = 302;
          uint256 internal constant MAX_STABLE_TOKENS = 303;
          uint256 internal constant MAX_IN_RATIO = 304;
          uint256 internal constant MAX_OUT_RATIO = 305;
          uint256 internal constant MIN_BPT_IN_FOR_TOKEN_OUT = 306;
          uint256 internal constant MAX_OUT_BPT_FOR_TOKEN_IN = 307;
          uint256 internal constant NORMALIZED_WEIGHT_INVARIANT = 308;
          uint256 internal constant INVALID_TOKEN = 309;
          uint256 internal constant UNHANDLED_JOIN_KIND = 310;
          uint256 internal constant ZERO_INVARIANT = 311;
          // Lib
          uint256 internal constant REENTRANCY = 400;
          uint256 internal constant SENDER_NOT_ALLOWED = 401;
          uint256 internal constant PAUSED = 402;
          uint256 internal constant PAUSE_WINDOW_EXPIRED = 403;
          uint256 internal constant MAX_PAUSE_WINDOW_DURATION = 404;
          uint256 internal constant MAX_BUFFER_PERIOD_DURATION = 405;
          uint256 internal constant INSUFFICIENT_BALANCE = 406;
          uint256 internal constant INSUFFICIENT_ALLOWANCE = 407;
          uint256 internal constant ERC20_TRANSFER_FROM_ZERO_ADDRESS = 408;
          uint256 internal constant ERC20_TRANSFER_TO_ZERO_ADDRESS = 409;
          uint256 internal constant ERC20_MINT_TO_ZERO_ADDRESS = 410;
          uint256 internal constant ERC20_BURN_FROM_ZERO_ADDRESS = 411;
          uint256 internal constant ERC20_APPROVE_FROM_ZERO_ADDRESS = 412;
          uint256 internal constant ERC20_APPROVE_TO_ZERO_ADDRESS = 413;
          uint256 internal constant ERC20_TRANSFER_EXCEEDS_ALLOWANCE = 414;
          uint256 internal constant ERC20_DECREASED_ALLOWANCE_BELOW_ZERO = 415;
          uint256 internal constant ERC20_TRANSFER_EXCEEDS_BALANCE = 416;
          uint256 internal constant ERC20_BURN_EXCEEDS_ALLOWANCE = 417;
          uint256 internal constant SAFE_ERC20_CALL_FAILED = 418;
          uint256 internal constant ADDRESS_INSUFFICIENT_BALANCE = 419;
          uint256 internal constant ADDRESS_CANNOT_SEND_VALUE = 420;
          uint256 internal constant SAFE_CAST_VALUE_CANT_FIT_INT256 = 421;
          uint256 internal constant GRANT_SENDER_NOT_ADMIN = 422;
          uint256 internal constant REVOKE_SENDER_NOT_ADMIN = 423;
          uint256 internal constant RENOUNCE_SENDER_NOT_ALLOWED = 424;
          uint256 internal constant BUFFER_PERIOD_EXPIRED = 425;
          // Vault
          uint256 internal constant INVALID_POOL_ID = 500;
          uint256 internal constant CALLER_NOT_POOL = 501;
          uint256 internal constant SENDER_NOT_ASSET_MANAGER = 502;
          uint256 internal constant USER_DOESNT_ALLOW_RELAYER = 503;
          uint256 internal constant INVALID_SIGNATURE = 504;
          uint256 internal constant EXIT_BELOW_MIN = 505;
          uint256 internal constant JOIN_ABOVE_MAX = 506;
          uint256 internal constant SWAP_LIMIT = 507;
          uint256 internal constant SWAP_DEADLINE = 508;
          uint256 internal constant CANNOT_SWAP_SAME_TOKEN = 509;
          uint256 internal constant UNKNOWN_AMOUNT_IN_FIRST_SWAP = 510;
          uint256 internal constant MALCONSTRUCTED_MULTIHOP_SWAP = 511;
          uint256 internal constant INTERNAL_BALANCE_OVERFLOW = 512;
          uint256 internal constant INSUFFICIENT_INTERNAL_BALANCE = 513;
          uint256 internal constant INVALID_ETH_INTERNAL_BALANCE = 514;
          uint256 internal constant INVALID_POST_LOAN_BALANCE = 515;
          uint256 internal constant INSUFFICIENT_ETH = 516;
          uint256 internal constant UNALLOCATED_ETH = 517;
          uint256 internal constant ETH_TRANSFER = 518;
          uint256 internal constant CANNOT_USE_ETH_SENTINEL = 519;
          uint256 internal constant TOKENS_MISMATCH = 520;
          uint256 internal constant TOKEN_NOT_REGISTERED = 521;
          uint256 internal constant TOKEN_ALREADY_REGISTERED = 522;
          uint256 internal constant TOKENS_ALREADY_SET = 523;
          uint256 internal constant TOKENS_LENGTH_MUST_BE_2 = 524;
          uint256 internal constant NONZERO_TOKEN_BALANCE = 525;
          uint256 internal constant BALANCE_TOTAL_OVERFLOW = 526;
          uint256 internal constant POOL_NO_TOKENS = 527;
          uint256 internal constant INSUFFICIENT_FLASH_LOAN_BALANCE = 528;
          // Fees
          uint256 internal constant SWAP_FEE_PERCENTAGE_TOO_HIGH = 600;
          uint256 internal constant FLASH_LOAN_FEE_PERCENTAGE_TOO_HIGH = 601;
          uint256 internal constant INSUFFICIENT_FLASH_LOAN_FEE_AMOUNT = 602;
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "./BalancerErrors.sol";
      import "./IAuthentication.sol";
      /**
       * @dev Building block for performing access control on external functions.
       *
       * This contract is used via the `authenticate` modifier (or the `_authenticateCaller` function), which can be applied
       * to external functions to only make them callable by authorized accounts.
       *
       * Derived contracts must implement the `_canPerform` function, which holds the actual access control logic.
       */
      abstract contract Authentication is IAuthentication {
          bytes32 private immutable _actionIdDisambiguator;
          /**
           * @dev The main purpose of the `actionIdDisambiguator` is to prevent accidental function selector collisions in
           * multi contract systems.
           *
           * There are two main uses for it:
           *  - if the contract is a singleton, any unique identifier can be used to make the associated action identifiers
           *    unique. The contract's own address is a good option.
           *  - if the contract belongs to a family that shares action identifiers for the same functions, an identifier
           *    shared by the entire family (and no other contract) should be used instead.
           */
          constructor(bytes32 actionIdDisambiguator) {
              _actionIdDisambiguator = actionIdDisambiguator;
          }
          /**
           * @dev Reverts unless the caller is allowed to call this function. Should only be applied to external functions.
           */
          modifier authenticate() {
              _authenticateCaller();
              _;
          }
          /**
           * @dev Reverts unless the caller is allowed to call the entry point function.
           */
          function _authenticateCaller() internal view {
              bytes32 actionId = getActionId(msg.sig);
              _require(_canPerform(actionId, msg.sender), Errors.SENDER_NOT_ALLOWED);
          }
          function getActionId(bytes4 selector) public view override returns (bytes32) {
              // Each external function is dynamically assigned an action identifier as the hash of the disambiguator and the
              // function selector. Disambiguation is necessary to avoid potential collisions in the function selectors of
              // multiple contracts.
              return keccak256(abi.encodePacked(_actionIdDisambiguator, selector));
          }
          function _canPerform(bytes32 actionId, address user) internal view virtual returns (bool);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "./BalancerErrors.sol";
      import "./ITemporarilyPausable.sol";
      /**
       * @dev Allows for a contract to be paused during an initial period after deployment, disabling functionality. Can be
       * used as an emergency switch in case a security vulnerability or threat is identified.
       *
       * The contract can only be paused during the Pause Window, a period that starts at deployment. It can also be
       * unpaused and repaused any number of times during this period. This is intended to serve as a safety measure: it lets
       * system managers react quickly to potentially dangerous situations, knowing that this action is reversible if careful
       * analysis later determines there was a false alarm.
       *
       * If the contract is paused when the Pause Window finishes, it will remain in the paused state through an additional
       * Buffer Period, after which it will be automatically unpaused forever. This is to ensure there is always enough time
       * to react to an emergency, even if the threat is discovered shortly before the Pause Window expires.
       *
       * Note that since the contract can only be paused within the Pause Window, unpausing during the Buffer Period is
       * irreversible.
       */
      abstract contract TemporarilyPausable is ITemporarilyPausable {
          // The Pause Window and Buffer Period are timestamp-based: they should not be relied upon for sub-minute accuracy.
          // solhint-disable not-rely-on-time
          uint256 private constant _MAX_PAUSE_WINDOW_DURATION = 90 days;
          uint256 private constant _MAX_BUFFER_PERIOD_DURATION = 30 days;
          uint256 private immutable _pauseWindowEndTime;
          uint256 private immutable _bufferPeriodEndTime;
          bool private _paused;
          constructor(uint256 pauseWindowDuration, uint256 bufferPeriodDuration) {
              _require(pauseWindowDuration <= _MAX_PAUSE_WINDOW_DURATION, Errors.MAX_PAUSE_WINDOW_DURATION);
              _require(bufferPeriodDuration <= _MAX_BUFFER_PERIOD_DURATION, Errors.MAX_BUFFER_PERIOD_DURATION);
              uint256 pauseWindowEndTime = block.timestamp + pauseWindowDuration;
              _pauseWindowEndTime = pauseWindowEndTime;
              _bufferPeriodEndTime = pauseWindowEndTime + bufferPeriodDuration;
          }
          /**
           * @dev Reverts if the contract is paused.
           */
          modifier whenNotPaused() {
              _ensureNotPaused();
              _;
          }
          /**
           * @dev Returns the current contract pause status, as well as the end times of the Pause Window and Buffer
           * Period.
           */
          function getPausedState()
              external
              view
              override
              returns (
                  bool paused,
                  uint256 pauseWindowEndTime,
                  uint256 bufferPeriodEndTime
              )
          {
              paused = !_isNotPaused();
              pauseWindowEndTime = _getPauseWindowEndTime();
              bufferPeriodEndTime = _getBufferPeriodEndTime();
          }
          /**
           * @dev Sets the pause state to `paused`. The contract can only be paused until the end of the Pause Window, and
           * unpaused until the end of the Buffer Period.
           *
           * Once the Buffer Period expires, this function reverts unconditionally.
           */
          function _setPaused(bool paused) internal {
              if (paused) {
                  _require(block.timestamp < _getPauseWindowEndTime(), Errors.PAUSE_WINDOW_EXPIRED);
              } else {
                  _require(block.timestamp < _getBufferPeriodEndTime(), Errors.BUFFER_PERIOD_EXPIRED);
              }
              _paused = paused;
              emit PausedStateChanged(paused);
          }
          /**
           * @dev Reverts if the contract is paused.
           */
          function _ensureNotPaused() internal view {
              _require(_isNotPaused(), Errors.PAUSED);
          }
          /**
           * @dev Returns true if the contract is unpaused.
           *
           * Once the Buffer Period expires, the gas cost of calling this function is reduced dramatically, as storage is no
           * longer accessed.
           */
          function _isNotPaused() internal view returns (bool) {
              // After the Buffer Period, the (inexpensive) timestamp check short-circuits the storage access.
              return block.timestamp > _getBufferPeriodEndTime() || !_paused;
          }
          // These getters lead to reduced bytecode size by inlining the immutable variables in a single place.
          function _getPauseWindowEndTime() private view returns (uint256) {
              return _pauseWindowEndTime;
          }
          function _getBufferPeriodEndTime() private view returns (uint256) {
              return _bufferPeriodEndTime;
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "./BalancerErrors.sol";
      import "./ISignaturesValidator.sol";
      import "../openzeppelin/EIP712.sol";
      /**
       * @dev Utility for signing Solidity function calls.
       *
       * This contract relies on the fact that Solidity contracts can be called with extra calldata, and enables
       * meta-transaction schemes by appending an EIP712 signature of the original calldata at the end.
       *
       * Derived contracts must implement the `_typeHash` function to map function selectors to EIP712 structs.
       */
      abstract contract SignaturesValidator is ISignaturesValidator, EIP712 {
          // The appended data consists of a deadline, plus the [v,r,s] signature. For simplicity, we use a full 256 bit slot
          // for each of these values, even if 'v' is typically an 8 bit value.
          uint256 internal constant _EXTRA_CALLDATA_LENGTH = 4 * 32;
          // Replay attack prevention for each user.
          mapping(address => uint256) internal _nextNonce;
          constructor(string memory name) EIP712(name, "1") {
              // solhint-disable-previous-line no-empty-blocks
          }
          function getDomainSeparator() external view override returns (bytes32) {
              return _domainSeparatorV4();
          }
          function getNextNonce(address user) external view override returns (uint256) {
              return _nextNonce[user];
          }
          /**
           * @dev Reverts with `errorCode` unless a valid signature for `user` was appended to the calldata.
           */
          function _validateSignature(address user, uint256 errorCode) internal {
              uint256 nextNonce = _nextNonce[user]++;
              _require(_isSignatureValid(user, nextNonce), errorCode);
          }
          function _isSignatureValid(address user, uint256 nonce) private view returns (bool) {
              uint256 deadline = _deadline();
              // The deadline is timestamp-based: it should not be relied upon for sub-minute accuracy.
              // solhint-disable-next-line not-rely-on-time
              if (deadline < block.timestamp) {
                  return false;
              }
              bytes32 typeHash = _typeHash();
              if (typeHash == bytes32(0)) {
                  // Prevent accidental signature validation for functions that don't have an associated type hash.
                  return false;
              }
              // All type hashes have this format: (bytes calldata, address sender, uint256 nonce, uint256 deadline).
              bytes32 structHash = keccak256(abi.encode(typeHash, keccak256(_calldata()), msg.sender, nonce, deadline));
              bytes32 digest = _hashTypedDataV4(structHash);
              (uint8 v, bytes32 r, bytes32 s) = _signature();
              address recoveredAddress = ecrecover(digest, v, r, s);
              // ecrecover returns the zero address on recover failure, so we need to handle that explicitly.
              return recoveredAddress != address(0) && recoveredAddress == user;
          }
          /**
           * @dev Returns the EIP712 type hash for the current entry point function, which can be identified by its function
           * selector (available as `msg.sig`).
           *
           * The type hash must conform to the following format:
           *  <name>(bytes calldata, address sender, uint256 nonce, uint256 deadline)
           *
           * If 0x00, all signatures will be considered invalid.
           */
          function _typeHash() internal view virtual returns (bytes32);
          /**
           * @dev Extracts the signature deadline from extra calldata.
           *
           * This function returns bogus data if no signature is included.
           */
          function _deadline() internal pure returns (uint256) {
              // The deadline is the first extra argument at the end of the original calldata.
              return uint256(_decodeExtraCalldataWord(0));
          }
          /**
           * @dev Extracts the signature parameters from extra calldata.
           *
           * This function returns bogus data if no signature is included. This is not a security risk, as that data would not
           * be considered a valid signature in the first place.
           */
          function _signature()
              internal
              pure
              returns (
                  uint8 v,
                  bytes32 r,
                  bytes32 s
              )
          {
              // v, r and s are appended after the signature deadline, in that order.
              v = uint8(uint256(_decodeExtraCalldataWord(0x20)));
              r = _decodeExtraCalldataWord(0x40);
              s = _decodeExtraCalldataWord(0x60);
          }
          /**
           * @dev Returns the original calldata, without the extra bytes containing the signature.
           *
           * This function returns bogus data if no signature is included.
           */
          function _calldata() internal pure returns (bytes memory result) {
              result = msg.data; // A calldata to memory assignment results in memory allocation and copy of contents.
              if (result.length > _EXTRA_CALLDATA_LENGTH) {
                  // solhint-disable-next-line no-inline-assembly
                  assembly {
                      // We simply overwrite the array length with the reduced one.
                      mstore(result, sub(calldatasize(), _EXTRA_CALLDATA_LENGTH))
                  }
              }
          }
          /**
           * @dev Returns a 256 bit word from 'extra' calldata, at some offset from the expected end of the original calldata.
           *
           * This function returns bogus data if no signature is included.
           */
          function _decodeExtraCalldataWord(uint256 offset) private pure returns (bytes32 result) {
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  result := calldataload(add(sub(calldatasize(), _EXTRA_CALLDATA_LENGTH), offset))
              }
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      import "../helpers/BalancerErrors.sol";
      // Based on the ReentrancyGuard library from OpenZeppelin contracts, altered to reduce bytecode size.
      // Modifier code is inlined by the compiler, which causes its code to appear multiple times in the codebase. By using
      // private functions, we achieve the same end result with slightly higher runtime gas costs but reduced bytecode size.
      /**
       * @dev Contract module that helps prevent reentrant calls to a function.
       *
       * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
       * available, which can be applied to functions to make sure there are no nested
       * (reentrant) calls to them.
       *
       * Note that because there is a single `nonReentrant` guard, functions marked as
       * `nonReentrant` may not call one another. This can be worked around by making
       * those functions `private`, and then adding `external` `nonReentrant` entry
       * points to them.
       *
       * TIP: If you would like to learn more about reentrancy and alternative ways
       * to protect against it, check out our blog post
       * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
       */
      abstract contract ReentrancyGuard {
          // Booleans are more expensive than uint256 or any type that takes up a full
          // word because each write operation emits an extra SLOAD to first read the
          // slot's contents, replace the bits taken up by the boolean, and then write
          // back. This is the compiler's defense against contract upgrades and
          // pointer aliasing, and it cannot be disabled.
          // The values being non-zero value makes deployment a bit more expensive,
          // but in exchange the refund on every call to nonReentrant will be lower in
          // amount. Since refunds are capped to a percentage of the total
          // transaction's gas, it is best to keep them low in cases like this one, to
          // increase the likelihood of the full refund coming into effect.
          uint256 private constant _NOT_ENTERED = 1;
          uint256 private constant _ENTERED = 2;
          uint256 private _status;
          constructor() {
              _status = _NOT_ENTERED;
          }
          /**
           * @dev Prevents a contract from calling itself, directly or indirectly.
           * Calling a `nonReentrant` function from another `nonReentrant`
           * function is not supported. It is possible to prevent this from happening
           * by making the `nonReentrant` function external, and make it call a
           * `private` function that does the actual work.
           */
          modifier nonReentrant() {
              _enterNonReentrant();
              _;
              _exitNonReentrant();
          }
          function _enterNonReentrant() private {
              // On the first call to nonReentrant, _status will be _NOT_ENTERED
              _require(_status != _ENTERED, Errors.REENTRANCY);
              // Any calls to nonReentrant after this point will fail
              _status = _ENTERED;
          }
          function _exitNonReentrant() private {
              // By storing the original value once again, a refund is triggered (see
              // https://eips.ethereum.org/EIPS/eip-2200)
              _status = _NOT_ENTERED;
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma experimental ABIEncoderV2;
      import "../../lib/openzeppelin/IERC20.sol";
      import "./IWETH.sol";
      import "./IAsset.sol";
      import "./IAuthorizer.sol";
      import "./IFlashLoanRecipient.sol";
      import "../ProtocolFeesCollector.sol";
      import "../../lib/helpers/ISignaturesValidator.sol";
      import "../../lib/helpers/ITemporarilyPausable.sol";
      pragma solidity ^0.7.0;
      /**
       * @dev Full external interface for the Vault core contract - no external or public methods exist in the contract that
       * don't override one of these declarations.
       */
      interface IVault is ISignaturesValidator, ITemporarilyPausable {
          // Generalities about the Vault:
          //
          // - Whenever documentation refers to 'tokens', it strictly refers to ERC20-compliant token contracts. Tokens are
          // transferred out of the Vault by calling the `IERC20.transfer` function, and transferred in by calling
          // `IERC20.transferFrom`. In these cases, the sender must have previously allowed the Vault to use their tokens by
          // calling `IERC20.approve`. The only deviation from the ERC20 standard that is supported is functions not returning
          // a boolean value: in these scenarios, a non-reverting call is assumed to be successful.
          //
          // - All non-view functions in the Vault are non-reentrant: calling them while another one is mid-execution (e.g.
          // while execution control is transferred to a token contract during a swap) will result in a revert. View
          // functions can be called in a re-reentrant way, but doing so might cause them to return inconsistent results.
          // Contracts calling view functions in the Vault must make sure the Vault has not already been entered.
          //
          // - View functions revert if referring to either unregistered Pools, or unregistered tokens for registered Pools.
          // Authorizer
          //
          // Some system actions are permissioned, like setting and collecting protocol fees. This permissioning system exists
          // outside of the Vault in the Authorizer contract: the Vault simply calls the Authorizer to check if the caller
          // can perform a given action.
          /**
           * @dev Returns the Vault's Authorizer.
           */
          function getAuthorizer() external view returns (IAuthorizer);
          /**
           * @dev Sets a new Authorizer for the Vault. The caller must be allowed by the current Authorizer to do this.
           *
           * Emits an `AuthorizerChanged` event.
           */
          function setAuthorizer(IAuthorizer newAuthorizer) external;
          /**
           * @dev Emitted when a new authorizer is set by `setAuthorizer`.
           */
          event AuthorizerChanged(IAuthorizer indexed newAuthorizer);
          // Relayers
          //
          // Additionally, it is possible for an account to perform certain actions on behalf of another one, using their
          // Vault ERC20 allowance and Internal Balance. These accounts are said to be 'relayers' for these Vault functions,
          // and are expected to be smart contracts with sound authentication mechanisms. For an account to be able to wield
          // this power, two things must occur:
          //  - The Authorizer must grant the account the permission to be a relayer for the relevant Vault function. This
          //    means that Balancer governance must approve each individual contract to act as a relayer for the intended
          //    functions.
          //  - Each user must approve the relayer to act on their behalf.
          // This double protection means users cannot be tricked into approving malicious relayers (because they will not
          // have been allowed by the Authorizer via governance), nor can malicious relayers approved by a compromised
          // Authorizer or governance drain user funds, since they would also need to be approved by each individual user.
          /**
           * @dev Returns true if `user` has approved `relayer` to act as a relayer for them.
           */
          function hasApprovedRelayer(address user, address relayer) external view returns (bool);
          /**
           * @dev Allows `relayer` to act as a relayer for `sender` if `approved` is true, and disallows it otherwise.
           *
           * Emits a `RelayerApprovalChanged` event.
           */
          function setRelayerApproval(
              address sender,
              address relayer,
              bool approved
          ) external;
          /**
           * @dev Emitted every time a relayer is approved or disapproved by `setRelayerApproval`.
           */
          event RelayerApprovalChanged(address indexed relayer, address indexed sender, bool approved);
          // Internal Balance
          //
          // Users can deposit tokens into the Vault, where they are allocated to their Internal Balance, and later
          // transferred or withdrawn. It can also be used as a source of tokens when joining Pools, as a destination
          // when exiting them, and as either when performing swaps. This usage of Internal Balance results in greatly reduced
          // gas costs when compared to relying on plain ERC20 transfers, leading to large savings for frequent users.
          //
          // Internal Balance management features batching, which means a single contract call can be used to perform multiple
          // operations of different kinds, with different senders and recipients, at once.
          /**
           * @dev Returns `user`'s Internal Balance for a set of tokens.
           */
          function getInternalBalance(address user, IERC20[] memory tokens) external view returns (uint256[] memory);
          /**
           * @dev Performs a set of user balance operations, which involve Internal Balance (deposit, withdraw or transfer)
           * and plain ERC20 transfers using the Vault's allowance. This last feature is particularly useful for relayers, as
           * it lets integrators reuse a user's Vault allowance.
           *
           * For each operation, if the caller is not `sender`, it must be an authorized relayer for them.
           */
          function manageUserBalance(UserBalanceOp[] memory ops) external payable;
          /**
           * @dev Data for `manageUserBalance` operations, which include the possibility for ETH to be sent and received
           without manual WETH wrapping or unwrapping.
           */
          struct UserBalanceOp {
              UserBalanceOpKind kind;
              IAsset asset;
              uint256 amount;
              address sender;
              address payable recipient;
          }
          // There are four possible operations in `manageUserBalance`:
          //
          // - DEPOSIT_INTERNAL
          // Increases the Internal Balance of the `recipient` account by transferring tokens from the corresponding
          // `sender`. The sender must have allowed the Vault to use their tokens via `IERC20.approve()`.
          //
          // ETH can be used by passing the ETH sentinel value as the asset and forwarding ETH in the call: it will be wrapped
          // and deposited as WETH. Any ETH amount remaining will be sent back to the caller (not the sender, which is
          // relevant for relayers).
          //
          // Emits an `InternalBalanceChanged` event.
          //
          //
          // - WITHDRAW_INTERNAL
          // Decreases the Internal Balance of the `sender` account by transferring tokens to the `recipient`.
          //
          // ETH can be used by passing the ETH sentinel value as the asset. This will deduct WETH instead, unwrap it and send
          // it to the recipient as ETH.
          //
          // Emits an `InternalBalanceChanged` event.
          //
          //
          // - TRANSFER_INTERNAL
          // Transfers tokens from the Internal Balance of the `sender` account to the Internal Balance of `recipient`.
          //
          // Reverts if the ETH sentinel value is passed.
          //
          // Emits an `InternalBalanceChanged` event.
          //
          //
          // - TRANSFER_EXTERNAL
          // Transfers tokens from `sender` to `recipient`, using the Vault's ERC20 allowance. This is typically used by
          // relayers, as it lets them reuse a user's Vault allowance.
          //
          // Reverts if the ETH sentinel value is passed.
          //
          // Emits an `ExternalBalanceTransfer` event.
          enum UserBalanceOpKind { DEPOSIT_INTERNAL, WITHDRAW_INTERNAL, TRANSFER_INTERNAL, TRANSFER_EXTERNAL }
          /**
           * @dev Emitted when a user's Internal Balance changes, either from calls to `manageUserBalance`, or through
           * interacting with Pools using Internal Balance.
           *
           * Because Internal Balance works exclusively with ERC20 tokens, ETH deposits and withdrawals will use the WETH
           * address.
           */
          event InternalBalanceChanged(address indexed user, IERC20 indexed token, int256 delta);
          /**
           * @dev Emitted when a user's Vault ERC20 allowance is used by the Vault to transfer tokens to an external account.
           */
          event ExternalBalanceTransfer(IERC20 indexed token, address indexed sender, address recipient, uint256 amount);
          // Pools
          //
          // There are three specialization settings for Pools, which allow for cheaper swaps at the cost of reduced
          // functionality:
          //
          //  - General: no specialization, suited for all Pools. IGeneralPool is used for swap request callbacks, passing the
          // balance of all tokens in the Pool. These Pools have the largest swap costs (because of the extra storage reads),
          // which increase with the number of registered tokens.
          //
          //  - Minimal Swap Info: IMinimalSwapInfoPool is used instead of IGeneralPool, which saves gas by only passing the
          // balance of the two tokens involved in the swap. This is suitable for some pricing algorithms, like the weighted
          // constant product one popularized by Balancer V1. Swap costs are smaller compared to general Pools, and are
          // independent of the number of registered tokens.
          //
          //  - Two Token: only allows two tokens to be registered. This achieves the lowest possible swap gas cost. Like
          // minimal swap info Pools, these are called via IMinimalSwapInfoPool.
          enum PoolSpecialization { GENERAL, MINIMAL_SWAP_INFO, TWO_TOKEN }
          /**
           * @dev Registers the caller account as a Pool with a given specialization setting. Returns the Pool's ID, which
           * is used in all Pool-related functions. Pools cannot be deregistered, nor can the Pool's specialization be
           * changed.
           *
           * The caller is expected to be a smart contract that implements either `IGeneralPool` or `IMinimalSwapInfoPool`,
           * depending on the chosen specialization setting. This contract is known as the Pool's contract.
           *
           * Note that the same contract may register itself as multiple Pools with unique Pool IDs, or in other words,
           * multiple Pools may share the same contract.
           *
           * Emits a `PoolRegistered` event.
           */
          function registerPool(PoolSpecialization specialization) external returns (bytes32);
          /**
           * @dev Emitted when a Pool is registered by calling `registerPool`.
           */
          event PoolRegistered(bytes32 indexed poolId, address indexed poolAddress, PoolSpecialization specialization);
          /**
           * @dev Returns a Pool's contract address and specialization setting.
           */
          function getPool(bytes32 poolId) external view returns (address, PoolSpecialization);
          /**
           * @dev Registers `tokens` for the `poolId` Pool. Must be called by the Pool's contract.
           *
           * Pools can only interact with tokens they have registered. Users join a Pool by transferring registered tokens,
           * exit by receiving registered tokens, and can only swap registered tokens.
           *
           * Each token can only be registered once. For Pools with the Two Token specialization, `tokens` must have a length
           * of two, that is, both tokens must be registered in the same `registerTokens` call, and they must be sorted in
           * ascending order.
           *
           * The `tokens` and `assetManagers` arrays must have the same length, and each entry in these indicates the Asset
           * Manager for the corresponding token. Asset Managers can manage a Pool's tokens via `managePoolBalance`,
           * depositing and withdrawing them directly, and can even set their balance to arbitrary amounts. They are therefore
           * expected to be highly secured smart contracts with sound design principles, and the decision to register an
           * Asset Manager should not be made lightly.
           *
           * Pools can choose not to assign an Asset Manager to a given token by passing in the zero address. Once an Asset
           * Manager is set, it cannot be changed except by deregistering the associated token and registering again with a
           * different Asset Manager.
           *
           * Emits a `TokensRegistered` event.
           */
          function registerTokens(
              bytes32 poolId,
              IERC20[] memory tokens,
              address[] memory assetManagers
          ) external;
          /**
           * @dev Emitted when a Pool registers tokens by calling `registerTokens`.
           */
          event TokensRegistered(bytes32 indexed poolId, IERC20[] tokens, address[] assetManagers);
          /**
           * @dev Deregisters `tokens` for the `poolId` Pool. Must be called by the Pool's contract.
           *
           * Only registered tokens (via `registerTokens`) can be deregistered. Additionally, they must have zero total
           * balance. For Pools with the Two Token specialization, `tokens` must have a length of two, that is, both tokens
           * must be deregistered in the same `deregisterTokens` call.
           *
           * A deregistered token can be re-registered later on, possibly with a different Asset Manager.
           *
           * Emits a `TokensDeregistered` event.
           */
          function deregisterTokens(bytes32 poolId, IERC20[] memory tokens) external;
          /**
           * @dev Emitted when a Pool deregisters tokens by calling `deregisterTokens`.
           */
          event TokensDeregistered(bytes32 indexed poolId, IERC20[] tokens);
          /**
           * @dev Returns detailed information for a Pool's registered token.
           *
           * `cash` is the number of tokens the Vault currently holds for the Pool. `managed` is the number of tokens
           * withdrawn and held outside the Vault by the Pool's token Asset Manager. The Pool's total balance for `token`
           * equals the sum of `cash` and `managed`.
           *
           * Internally, `cash` and `managed` are stored using 112 bits. No action can ever cause a Pool's token `cash`,
           * `managed` or `total` balance to be greater than 2^112 - 1.
           *
           * `lastChangeBlock` is the number of the block in which `token`'s total balance was last modified (via either a
           * join, exit, swap, or Asset Manager update). This value is useful to avoid so-called 'sandwich attacks', for
           * example when developing price oracles. A change of zero (e.g. caused by a swap with amount zero) is considered a
           * change for this purpose, and will update `lastChangeBlock`.
           *
           * `assetManager` is the Pool's token Asset Manager.
           */
          function getPoolTokenInfo(bytes32 poolId, IERC20 token)
              external
              view
              returns (
                  uint256 cash,
                  uint256 managed,
                  uint256 lastChangeBlock,
                  address assetManager
              );
          /**
           * @dev Returns a Pool's registered tokens, the total balance for each, and the latest block when *any* of
           * the tokens' `balances` changed.
           *
           * The order of the `tokens` array is the same order that will be used in `joinPool`, `exitPool`, as well as in all
           * Pool hooks (where applicable). Calls to `registerTokens` and `deregisterTokens` may change this order.
           *
           * If a Pool only registers tokens once, and these are sorted in ascending order, they will be stored in the same
           * order as passed to `registerTokens`.
           *
           * Total balances include both tokens held by the Vault and those withdrawn by the Pool's Asset Managers. These are
           * the amounts used by joins, exits and swaps. For a detailed breakdown of token balances, use `getPoolTokenInfo`
           * instead.
           */
          function getPoolTokens(bytes32 poolId)
              external
              view
              returns (
                  IERC20[] memory tokens,
                  uint256[] memory balances,
                  uint256 lastChangeBlock
              );
          /**
           * @dev Called by users to join a Pool, which transfers tokens from `sender` into the Pool's balance. This will
           * trigger custom Pool behavior, which will typically grant something in return to `recipient` - often tokenized
           * Pool shares.
           *
           * If the caller is not `sender`, it must be an authorized relayer for them.
           *
           * The `assets` and `maxAmountsIn` arrays must have the same length, and each entry indicates the maximum amount
           * to send for each asset. The amounts to send are decided by the Pool and not the Vault: it just enforces
           * these maximums.
           *
           * If joining a Pool that holds WETH, it is possible to send ETH directly: the Vault will do the wrapping. To enable
           * this mechanism, the IAsset sentinel value (the zero address) must be passed in the `assets` array instead of the
           * WETH address. Note that it is not possible to combine ETH and WETH in the same join. Any excess ETH will be sent
           * back to the caller (not the sender, which is important for relayers).
           *
           * `assets` must have the same length and order as the array returned by `getPoolTokens`. This prevents issues when
           * interacting with Pools that register and deregister tokens frequently. If sending ETH however, the array must be
           * sorted *before* replacing the WETH address with the ETH sentinel value (the zero address), which means the final
           * `assets` array might not be sorted. Pools with no registered tokens cannot be joined.
           *
           * If `fromInternalBalance` is true, the caller's Internal Balance will be preferred: ERC20 transfers will only
           * be made for the difference between the requested amount and Internal Balance (if any). Note that ETH cannot be
           * withdrawn from Internal Balance: attempting to do so will trigger a revert.
           *
           * This causes the Vault to call the `IBasePool.onJoinPool` hook on the Pool's contract, where Pools implement
           * their own custom logic. This typically requires additional information from the user (such as the expected number
           * of Pool shares). This can be encoded in the `userData` argument, which is ignored by the Vault and passed
           * directly to the Pool's contract, as is `recipient`.
           *
           * Emits a `PoolBalanceChanged` event.
           */
          function joinPool(
              bytes32 poolId,
              address sender,
              address recipient,
              JoinPoolRequest memory request
          ) external payable;
          struct JoinPoolRequest {
              IAsset[] assets;
              uint256[] maxAmountsIn;
              bytes userData;
              bool fromInternalBalance;
          }
          /**
           * @dev Called by users to exit a Pool, which transfers tokens from the Pool's balance to `recipient`. This will
           * trigger custom Pool behavior, which will typically ask for something in return from `sender` - often tokenized
           * Pool shares. The amount of tokens that can be withdrawn is limited by the Pool's `cash` balance (see
           * `getPoolTokenInfo`).
           *
           * If the caller is not `sender`, it must be an authorized relayer for them.
           *
           * The `tokens` and `minAmountsOut` arrays must have the same length, and each entry in these indicates the minimum
           * token amount to receive for each token contract. The amounts to send are decided by the Pool and not the Vault:
           * it just enforces these minimums.
           *
           * If exiting a Pool that holds WETH, it is possible to receive ETH directly: the Vault will do the unwrapping. To
           * enable this mechanism, the IAsset sentinel value (the zero address) must be passed in the `assets` array instead
           * of the WETH address. Note that it is not possible to combine ETH and WETH in the same exit.
           *
           * `assets` must have the same length and order as the array returned by `getPoolTokens`. This prevents issues when
           * interacting with Pools that register and deregister tokens frequently. If receiving ETH however, the array must
           * be sorted *before* replacing the WETH address with the ETH sentinel value (the zero address), which means the
           * final `assets` array might not be sorted. Pools with no registered tokens cannot be exited.
           *
           * If `toInternalBalance` is true, the tokens will be deposited to `recipient`'s Internal Balance. Otherwise,
           * an ERC20 transfer will be performed. Note that ETH cannot be deposited to Internal Balance: attempting to
           * do so will trigger a revert.
           *
           * `minAmountsOut` is the minimum amount of tokens the user expects to get out of the Pool, for each token in the
           * `tokens` array. This array must match the Pool's registered tokens.
           *
           * This causes the Vault to call the `IBasePool.onExitPool` hook on the Pool's contract, where Pools implement
           * their own custom logic. This typically requires additional information from the user (such as the expected number
           * of Pool shares to return). This can be encoded in the `userData` argument, which is ignored by the Vault and
           * passed directly to the Pool's contract.
           *
           * Emits a `PoolBalanceChanged` event.
           */
          function exitPool(
              bytes32 poolId,
              address sender,
              address payable recipient,
              ExitPoolRequest memory request
          ) external;
          struct ExitPoolRequest {
              IAsset[] assets;
              uint256[] minAmountsOut;
              bytes userData;
              bool toInternalBalance;
          }
          /**
           * @dev Emitted when a user joins or exits a Pool by calling `joinPool` or `exitPool`, respectively.
           */
          event PoolBalanceChanged(
              bytes32 indexed poolId,
              address indexed liquidityProvider,
              IERC20[] tokens,
              int256[] deltas,
              uint256[] protocolFeeAmounts
          );
          enum PoolBalanceChangeKind { JOIN, EXIT }
          // Swaps
          //
          // Users can swap tokens with Pools by calling the `swap` and `batchSwap` functions. To do this,
          // they need not trust Pool contracts in any way: all security checks are made by the Vault. They must however be
          // aware of the Pools' pricing algorithms in order to estimate the prices Pools will quote.
          //
          // The `swap` function executes a single swap, while `batchSwap` can perform multiple swaps in sequence.
          // In each individual swap, tokens of one kind are sent from the sender to the Pool (this is the 'token in'),
          // and tokens of another kind are sent from the Pool to the recipient in exchange (this is the 'token out').
          // More complex swaps, such as one token in to multiple tokens out can be achieved by batching together
          // individual swaps.
          //
          // There are two swap kinds:
          //  - 'given in' swaps, where the amount of tokens in (sent to the Pool) is known, and the Pool determines (via the
          // `onSwap` hook) the amount of tokens out (to send to the recipient).
          //  - 'given out' swaps, where the amount of tokens out (received from the Pool) is known, and the Pool determines
          // (via the `onSwap` hook) the amount of tokens in (to receive from the sender).
          //
          // Additionally, it is possible to chain swaps using a placeholder input amount, which the Vault replaces with
          // the calculated output of the previous swap. If the previous swap was 'given in', this will be the calculated
          // tokenOut amount. If the previous swap was 'given out', it will use the calculated tokenIn amount. These extended
          // swaps are known as 'multihop' swaps, since they 'hop' through a number of intermediate tokens before arriving at
          // the final intended token.
          //
          // In all cases, tokens are only transferred in and out of the Vault (or withdrawn from and deposited into Internal
          // Balance) after all individual swaps have been completed, and the net token balance change computed. This makes
          // certain swap patterns, such as multihops, or swaps that interact with the same token pair in multiple Pools, cost
          // much less gas than they would otherwise.
          //
          // It also means that under certain conditions it is possible to perform arbitrage by swapping with multiple
          // Pools in a way that results in net token movement out of the Vault (profit), with no tokens being sent in (only
          // updating the Pool's internal accounting).
          //
          // To protect users from front-running or the market changing rapidly, they supply a list of 'limits' for each token
          // involved in the swap, where either the maximum number of tokens to send (by passing a positive value) or the
          // minimum amount of tokens to receive (by passing a negative value) is specified.
          //
          // Additionally, a 'deadline' timestamp can also be provided, forcing the swap to fail if it occurs after
          // this point in time (e.g. if the transaction failed to be included in a block promptly).
          //
          // If interacting with Pools that hold WETH, it is possible to both send and receive ETH directly: the Vault will do
          // the wrapping and unwrapping. To enable this mechanism, the IAsset sentinel value (the zero address) must be
          // passed in the `assets` array instead of the WETH address. Note that it is possible to combine ETH and WETH in the
          // same swap. Any excess ETH will be sent back to the caller (not the sender, which is relevant for relayers).
          //
          // Finally, Internal Balance can be used when either sending or receiving tokens.
          enum SwapKind { GIVEN_IN, GIVEN_OUT }
          /**
           * @dev Performs a swap with a single Pool.
           *
           * If the swap is 'given in' (the number of tokens to send to the Pool is known), it returns the amount of tokens
           * taken from the Pool, which must be greater than or equal to `limit`.
           *
           * If the swap is 'given out' (the number of tokens to take from the Pool is known), it returns the amount of tokens
           * sent to the Pool, which must be less than or equal to `limit`.
           *
           * Internal Balance usage and the recipient are determined by the `funds` struct.
           *
           * Emits a `Swap` event.
           */
          function swap(
              SingleSwap memory singleSwap,
              FundManagement memory funds,
              uint256 limit,
              uint256 deadline
          ) external payable returns (uint256);
          /**
           * @dev Data for a single swap executed by `swap`. `amount` is either `amountIn` or `amountOut` depending on
           * the `kind` value.
           *
           * `assetIn` and `assetOut` are either token addresses, or the IAsset sentinel value for ETH (the zero address).
           * Note that Pools never interact with ETH directly: it will be wrapped to or unwrapped from WETH by the Vault.
           *
           * The `userData` field is ignored by the Vault, but forwarded to the Pool in the `onSwap` hook, and may be
           * used to extend swap behavior.
           */
          struct SingleSwap {
              bytes32 poolId;
              SwapKind kind;
              IAsset assetIn;
              IAsset assetOut;
              uint256 amount;
              bytes userData;
          }
          /**
           * @dev Performs a series of swaps with one or multiple Pools. In each individual swap, the caller determines either
           * the amount of tokens sent to or received from the Pool, depending on the `kind` value.
           *
           * Returns an array with the net Vault asset balance deltas. Positive amounts represent tokens (or ETH) sent to the
           * Vault, and negative amounts represent tokens (or ETH) sent by the Vault. Each delta corresponds to the asset at
           * the same index in the `assets` array.
           *
           * Swaps are executed sequentially, in the order specified by the `swaps` array. Each array element describes a
           * Pool, the token to be sent to this Pool, the token to receive from it, and an amount that is either `amountIn` or
           * `amountOut` depending on the swap kind.
           *
           * Multihop swaps can be executed by passing an `amount` value of zero for a swap. This will cause the amount in/out
           * of the previous swap to be used as the amount in for the current one. In a 'given in' swap, 'tokenIn' must equal
           * the previous swap's `tokenOut`. For a 'given out' swap, `tokenOut` must equal the previous swap's `tokenIn`.
           *
           * The `assets` array contains the addresses of all assets involved in the swaps. These are either token addresses,
           * or the IAsset sentinel value for ETH (the zero address). Each entry in the `swaps` array specifies tokens in and
           * out by referencing an index in `assets`. Note that Pools never interact with ETH directly: it will be wrapped to
           * or unwrapped from WETH by the Vault.
           *
           * Internal Balance usage, sender, and recipient are determined by the `funds` struct. The `limits` array specifies
           * the minimum or maximum amount of each token the vault is allowed to transfer.
           *
           * `batchSwap` can be used to make a single swap, like `swap` does, but doing so requires more gas than the
           * equivalent `swap` call.
           *
           * Emits `Swap` events.
           */
          function batchSwap(
              SwapKind kind,
              BatchSwapStep[] memory swaps,
              IAsset[] memory assets,
              FundManagement memory funds,
              int256[] memory limits,
              uint256 deadline
          ) external payable returns (int256[] memory);
          /**
           * @dev Data for each individual swap executed by `batchSwap`. The asset in and out fields are indexes into the
           * `assets` array passed to that function, and ETH assets are converted to WETH.
           *
           * If `amount` is zero, the multihop mechanism is used to determine the actual amount based on the amount in/out
           * from the previous swap, depending on the swap kind.
           *
           * The `userData` field is ignored by the Vault, but forwarded to the Pool in the `onSwap` hook, and may be
           * used to extend swap behavior.
           */
          struct BatchSwapStep {
              bytes32 poolId;
              uint256 assetInIndex;
              uint256 assetOutIndex;
              uint256 amount;
              bytes userData;
          }
          /**
           * @dev Emitted for each individual swap performed by `swap` or `batchSwap`.
           */
          event Swap(
              bytes32 indexed poolId,
              IERC20 indexed tokenIn,
              IERC20 indexed tokenOut,
              uint256 amountIn,
              uint256 amountOut
          );
          /**
           * @dev All tokens in a swap are either sent from the `sender` account to the Vault, or from the Vault to the
           * `recipient` account.
           *
           * If the caller is not `sender`, it must be an authorized relayer for them.
           *
           * If `fromInternalBalance` is true, the `sender`'s Internal Balance will be preferred, performing an ERC20
           * transfer for the difference between the requested amount and the User's Internal Balance (if any). The `sender`
           * must have allowed the Vault to use their tokens via `IERC20.approve()`. This matches the behavior of
           * `joinPool`.
           *
           * If `toInternalBalance` is true, tokens will be deposited to `recipient`'s internal balance instead of
           * transferred. This matches the behavior of `exitPool`.
           *
           * Note that ETH cannot be deposited to or withdrawn from Internal Balance: attempting to do so will trigger a
           * revert.
           */
          struct FundManagement {
              address sender;
              bool fromInternalBalance;
              address payable recipient;
              bool toInternalBalance;
          }
          /**
           * @dev Simulates a call to `batchSwap`, returning an array of Vault asset deltas. Calls to `swap` cannot be
           * simulated directly, but an equivalent `batchSwap` call can and will yield the exact same result.
           *
           * Each element in the array corresponds to the asset at the same index, and indicates the number of tokens (or ETH)
           * the Vault would take from the sender (if positive) or send to the recipient (if negative). The arguments it
           * receives are the same that an equivalent `batchSwap` call would receive.
           *
           * Unlike `batchSwap`, this function performs no checks on the sender or recipient field in the `funds` struct.
           * This makes it suitable to be called by off-chain applications via eth_call without needing to hold tokens,
           * approve them for the Vault, or even know a user's address.
           *
           * Note that this function is not 'view' (due to implementation details): the client code must explicitly execute
           * eth_call instead of eth_sendTransaction.
           */
          function queryBatchSwap(
              SwapKind kind,
              BatchSwapStep[] memory swaps,
              IAsset[] memory assets,
              FundManagement memory funds
          ) external returns (int256[] memory assetDeltas);
          // Flash Loans
          /**
           * @dev Performs a 'flash loan', sending tokens to `recipient`, executing the `receiveFlashLoan` hook on it,
           * and then reverting unless the tokens plus a proportional protocol fee have been returned.
           *
           * The `tokens` and `amounts` arrays must have the same length, and each entry in these indicates the loan amount
           * for each token contract. `tokens` must be sorted in ascending order.
           *
           * The 'userData' field is ignored by the Vault, and forwarded as-is to `recipient` as part of the
           * `receiveFlashLoan` call.
           *
           * Emits `FlashLoan` events.
           */
          function flashLoan(
              IFlashLoanRecipient recipient,
              IERC20[] memory tokens,
              uint256[] memory amounts,
              bytes memory userData
          ) external;
          /**
           * @dev Emitted for each individual flash loan performed by `flashLoan`.
           */
          event FlashLoan(IFlashLoanRecipient indexed recipient, IERC20 indexed token, uint256 amount, uint256 feeAmount);
          // Asset Management
          //
          // Each token registered for a Pool can be assigned an Asset Manager, which is able to freely withdraw the Pool's
          // tokens from the Vault, deposit them, or assign arbitrary values to its `managed` balance (see
          // `getPoolTokenInfo`). This makes them extremely powerful and dangerous. Even if an Asset Manager only directly
          // controls one of the tokens in a Pool, a malicious manager could set that token's balance to manipulate the
          // prices of the other tokens, and then drain the Pool with swaps. The risk of using Asset Managers is therefore
          // not constrained to the tokens they are managing, but extends to the entire Pool's holdings.
          //
          // However, a properly designed Asset Manager smart contract can be safely used for the Pool's benefit,
          // for example by lending unused tokens out for interest, or using them to participate in voting protocols.
          //
          // This concept is unrelated to the IAsset interface.
          /**
           * @dev Performs a set of Pool balance operations, which may be either withdrawals, deposits or updates.
           *
           * Pool Balance management features batching, which means a single contract call can be used to perform multiple
           * operations of different kinds, with different Pools and tokens, at once.
           *
           * For each operation, the caller must be registered as the Asset Manager for `token` in `poolId`.
           */
          function managePoolBalance(PoolBalanceOp[] memory ops) external;
          struct PoolBalanceOp {
              PoolBalanceOpKind kind;
              bytes32 poolId;
              IERC20 token;
              uint256 amount;
          }
          /**
           * Withdrawals decrease the Pool's cash, but increase its managed balance, leaving the total balance unchanged.
           *
           * Deposits increase the Pool's cash, but decrease its managed balance, leaving the total balance unchanged.
           *
           * Updates don't affect the Pool's cash balance, but because the managed balance changes, it does alter the total.
           * The external amount can be either increased or decreased by this call (i.e., reporting a gain or a loss).
           */
          enum PoolBalanceOpKind { WITHDRAW, DEPOSIT, UPDATE }
          /**
           * @dev Emitted when a Pool's token Asset Manager alters its balance via `managePoolBalance`.
           */
          event PoolBalanceManaged(
              bytes32 indexed poolId,
              address indexed assetManager,
              IERC20 indexed token,
              int256 cashDelta,
              int256 managedDelta
          );
          // Protocol Fees
          //
          // Some operations cause the Vault to collect tokens in the form of protocol fees, which can then be withdrawn by
          // permissioned accounts.
          //
          // There are two kinds of protocol fees:
          //
          //  - flash loan fees: charged on all flash loans, as a percentage of the amounts lent.
          //
          //  - swap fees: a percentage of the fees charged by Pools when performing swaps. For a number of reasons, including
          // swap gas costs and interface simplicity, protocol swap fees are not charged on each individual swap. Rather,
          // Pools are expected to keep track of how much they have charged in swap fees, and pay any outstanding debts to the
          // Vault when they are joined or exited. This prevents users from joining a Pool with unpaid debt, as well as
          // exiting a Pool in debt without first paying their share.
          /**
           * @dev Returns the current protocol fee module.
           */
          function getProtocolFeesCollector() external view returns (ProtocolFeesCollector);
          /**
           * @dev Safety mechanism to pause most Vault operations in the event of an emergency - typically detection of an
           * error in some part of the system.
           *
           * The Vault can only be paused during an initial time period, after which pausing is forever disabled.
           *
           * While the contract is paused, the following features are disabled:
           * - depositing and transferring internal balance
           * - transferring external balance (using the Vault's allowance)
           * - swaps
           * - joining Pools
           * - Asset Manager interactions
           *
           * Internal Balance can still be withdrawn, and Pools exited.
           */
          function setPaused(bool paused) external;
          /**
           * @dev Returns the Vault's WETH instance.
           */
          function WETH() external view returns (IWETH);
          // solhint-disable-previous-line func-name-mixedcase
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      interface IAuthentication {
          /**
           * @dev Returns the action identifier associated with the external function described by `selector`.
           */
          function getActionId(bytes4 selector) external view returns (bytes32);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      /**
       * @dev Interface for the TemporarilyPausable helper.
       */
      interface ITemporarilyPausable {
          /**
           * @dev Emitted every time the pause state changes by `_setPaused`.
           */
          event PausedStateChanged(bool paused);
          /**
           * @dev Returns the current paused state.
           */
          function getPausedState()
              external
              view
              returns (
                  bool paused,
                  uint256 pauseWindowEndTime,
                  uint256 bufferPeriodEndTime
              );
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      /**
       * @dev Interface for the SignatureValidator helper, used to support meta-transactions.
       */
      interface ISignaturesValidator {
          /**
           * @dev Returns the EIP712 domain separator.
           */
          function getDomainSeparator() external view returns (bytes32);
          /**
           * @dev Returns the next nonce used by an address to sign messages.
           */
          function getNextNonce(address user) external view returns (uint256);
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      /**
       * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
       *
       * The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
       * thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
       * they need in their contracts using a combination of `abi.encode` and `keccak256`.
       *
       * This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
       * scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
       * ({_hashTypedDataV4}).
       *
       * The implementation of the domain separator was designed to be as efficient as possible while still properly updating
       * the chain id to protect against replay attacks on an eventual fork of the chain.
       *
       * NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
       * https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
       *
       * _Available since v3.4._
       */
      abstract contract EIP712 {
          /* solhint-disable var-name-mixedcase */
          bytes32 private immutable _HASHED_NAME;
          bytes32 private immutable _HASHED_VERSION;
          bytes32 private immutable _TYPE_HASH;
          /* solhint-enable var-name-mixedcase */
          /**
           * @dev Initializes the domain separator and parameter caches.
           *
           * The meaning of `name` and `version` is specified in
           * https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
           *
           * - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
           * - `version`: the current major version of the signing domain.
           *
           * NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
           * contract upgrade].
           */
          constructor(string memory name, string memory version) {
              _HASHED_NAME = keccak256(bytes(name));
              _HASHED_VERSION = keccak256(bytes(version));
              _TYPE_HASH = keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
          }
          /**
           * @dev Returns the domain separator for the current chain.
           */
          function _domainSeparatorV4() internal view virtual returns (bytes32) {
              return keccak256(abi.encode(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION, _getChainId(), address(this)));
          }
          /**
           * @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
           * function returns the hash of the fully encoded EIP712 message for this domain.
           *
           * This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
           *
           * ```solidity
           * bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
           *     keccak256("Mail(address to,string contents)"),
           *     mailTo,
           *     keccak256(bytes(mailContents))
           * )));
           * address signer = ECDSA.recover(digest, signature);
           * ```
           */
          function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
              return keccak256(abi.encodePacked("\\x19\\x01", _domainSeparatorV4(), structHash));
          }
          function _getChainId() private view returns (uint256 chainId) {
              // Silence state mutability warning without generating bytecode.
              // See https://github.com/ethereum/solidity/issues/10090#issuecomment-741789128 and
              // https://github.com/ethereum/solidity/issues/2691
              this;
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  chainId := chainid()
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      /**
       * @dev This is an empty interface used to represent either ERC20-conforming token contracts or ETH (using the zero
       * address sentinel value). We're just relying on the fact that `interface` can be used to declare new address-like
       * types.
       *
       * This concept is unrelated to a Pool's Asset Managers.
       */
      interface IAsset {
          // solhint-disable-previous-line no-empty-blocks
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      // Inspired by Aave Protocol's IFlashLoanReceiver.
      import "../../lib/openzeppelin/IERC20.sol";
      interface IFlashLoanRecipient {
          /**
           * @dev When `flashLoan` is called on the Vault, it invokes the `receiveFlashLoan` hook on the recipient.
           *
           * At the time of the call, the Vault will have transferred `amounts` for `tokens` to the recipient. Before this
           * call returns, the recipient must have transferred `amounts` plus `feeAmounts` for each token back to the
           * Vault, or else the entire flash loan will revert.
           *
           * `userData` is the same value passed in the `IVault.flashLoan` call.
           */
          function receiveFlashLoan(
              IERC20[] memory tokens,
              uint256[] memory amounts,
              uint256[] memory feeAmounts,
              bytes memory userData
          ) external;
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../lib/openzeppelin/IERC20.sol";
      import "../lib/helpers/InputHelpers.sol";
      import "../lib/helpers/Authentication.sol";
      import "../lib/openzeppelin/ReentrancyGuard.sol";
      import "../lib/openzeppelin/SafeERC20.sol";
      import "./interfaces/IVault.sol";
      import "./interfaces/IAuthorizer.sol";
      /**
       * @dev This an auxiliary contract to the Vault, deployed by it during construction. It offloads some of the tasks the
       * Vault performs to reduce its overall bytecode size.
       *
       * The current values for all protocol fee percentages are stored here, and any tokens charged as protocol fees are
       * sent to this contract, where they may be withdrawn by authorized entities. All authorization tasks are delegated
       * to the Vault's own authorizer.
       */
      contract ProtocolFeesCollector is Authentication, ReentrancyGuard {
          using SafeERC20 for IERC20;
          // Absolute maximum fee percentages (1e18 = 100%, 1e16 = 1%).
          uint256 private constant _MAX_PROTOCOL_SWAP_FEE_PERCENTAGE = 50e16; // 50%
          uint256 private constant _MAX_PROTOCOL_FLASH_LOAN_FEE_PERCENTAGE = 1e16; // 1%
          IVault public immutable vault;
          // All fee percentages are 18-decimal fixed point numbers.
          // The swap fee is charged whenever a swap occurs, as a percentage of the fee charged by the Pool. These are not
          // actually charged on each individual swap: the `Vault` relies on the Pools being honest and reporting fees due
          // when users join and exit them.
          uint256 private _swapFeePercentage;
          // The flash loan fee is charged whenever a flash loan occurs, as a percentage of the tokens lent.
          uint256 private _flashLoanFeePercentage;
          event SwapFeePercentageChanged(uint256 newSwapFeePercentage);
          event FlashLoanFeePercentageChanged(uint256 newFlashLoanFeePercentage);
          constructor(IVault _vault)
              // The ProtocolFeesCollector is a singleton, so it simply uses its own address to disambiguate action
              // identifiers.
              Authentication(bytes32(uint256(address(this))))
          {
              vault = _vault;
          }
          function withdrawCollectedFees(
              IERC20[] calldata tokens,
              uint256[] calldata amounts,
              address recipient
          ) external nonReentrant authenticate {
              InputHelpers.ensureInputLengthMatch(tokens.length, amounts.length);
              for (uint256 i = 0; i < tokens.length; ++i) {
                  IERC20 token = tokens[i];
                  uint256 amount = amounts[i];
                  token.safeTransfer(recipient, amount);
              }
          }
          function setSwapFeePercentage(uint256 newSwapFeePercentage) external authenticate {
              _require(newSwapFeePercentage <= _MAX_PROTOCOL_SWAP_FEE_PERCENTAGE, Errors.SWAP_FEE_PERCENTAGE_TOO_HIGH);
              _swapFeePercentage = newSwapFeePercentage;
              emit SwapFeePercentageChanged(newSwapFeePercentage);
          }
          function setFlashLoanFeePercentage(uint256 newFlashLoanFeePercentage) external authenticate {
              _require(
                  newFlashLoanFeePercentage <= _MAX_PROTOCOL_FLASH_LOAN_FEE_PERCENTAGE,
                  Errors.FLASH_LOAN_FEE_PERCENTAGE_TOO_HIGH
              );
              _flashLoanFeePercentage = newFlashLoanFeePercentage;
              emit FlashLoanFeePercentageChanged(newFlashLoanFeePercentage);
          }
          function getSwapFeePercentage() external view returns (uint256) {
              return _swapFeePercentage;
          }
          function getFlashLoanFeePercentage() external view returns (uint256) {
              return _flashLoanFeePercentage;
          }
          function getCollectedFeeAmounts(IERC20[] memory tokens) external view returns (uint256[] memory feeAmounts) {
              feeAmounts = new uint256[](tokens.length);
              for (uint256 i = 0; i < tokens.length; ++i) {
                  feeAmounts[i] = tokens[i].balanceOf(address(this));
              }
          }
          function getAuthorizer() external view returns (IAuthorizer) {
              return _getAuthorizer();
          }
          function _canPerform(bytes32 actionId, address account) internal view override returns (bool) {
              return _getAuthorizer().canPerform(actionId, account, address(this));
          }
          function _getAuthorizer() internal view returns (IAuthorizer) {
              return vault.getAuthorizer();
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "../openzeppelin/IERC20.sol";
      import "./BalancerErrors.sol";
      import "../../vault/interfaces/IAsset.sol";
      library InputHelpers {
          function ensureInputLengthMatch(uint256 a, uint256 b) internal pure {
              _require(a == b, Errors.INPUT_LENGTH_MISMATCH);
          }
          function ensureInputLengthMatch(
              uint256 a,
              uint256 b,
              uint256 c
          ) internal pure {
              _require(a == b && b == c, Errors.INPUT_LENGTH_MISMATCH);
          }
          function ensureArrayIsSorted(IAsset[] memory array) internal pure {
              address[] memory addressArray;
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  addressArray := array
              }
              ensureArrayIsSorted(addressArray);
          }
          function ensureArrayIsSorted(IERC20[] memory array) internal pure {
              address[] memory addressArray;
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  addressArray := array
              }
              ensureArrayIsSorted(addressArray);
          }
          function ensureArrayIsSorted(address[] memory array) internal pure {
              if (array.length < 2) {
                  return;
              }
              address previous = array[0];
              for (uint256 i = 1; i < array.length; ++i) {
                  address current = array[i];
                  _require(previous < current, Errors.UNSORTED_ARRAY);
                  previous = current;
              }
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      import "../helpers/BalancerErrors.sol";
      import "./IERC20.sol";
      /**
       * @title SafeERC20
       * @dev Wrappers around ERC20 operations that throw on failure (when the token
       * contract returns false). Tokens that return no value (and instead revert or
       * throw on failure) are also supported, non-reverting calls are assumed to be
       * successful.
       * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
       * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
       */
      library SafeERC20 {
          function safeTransfer(
              IERC20 token,
              address to,
              uint256 value
          ) internal {
              _callOptionalReturn(address(token), abi.encodeWithSelector(token.transfer.selector, to, value));
          }
          function safeTransferFrom(
              IERC20 token,
              address from,
              address to,
              uint256 value
          ) internal {
              _callOptionalReturn(address(token), abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
          }
          /**
           * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
           * on the return value: the return value is optional (but if data is returned, it must not be false).
           *
           * WARNING: `token` is assumed to be a contract: calls to EOAs will *not* revert.
           */
          function _callOptionalReturn(address token, bytes memory data) private {
              // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
              // we're implementing it ourselves.
              (bool success, bytes memory returndata) = token.call(data);
              // If the low-level call didn't succeed we return whatever was returned from it.
              assembly {
                  if eq(success, 0) {
                      returndatacopy(0, 0, returndatasize())
                      revert(0, returndatasize())
                  }
              }
              // Finally we check the returndata size is either zero or true - note that this check will always pass for EOAs
              _require(returndata.length == 0 || abi.decode(returndata, (bool)), Errors.SAFE_ERC20_CALL_FAILED);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../lib/math/FixedPoint.sol";
      import "../lib/helpers/BalancerErrors.sol";
      import "../lib/openzeppelin/IERC20.sol";
      import "../lib/openzeppelin/ReentrancyGuard.sol";
      import "../lib/openzeppelin/SafeERC20.sol";
      import "./ProtocolFeesCollector.sol";
      import "./VaultAuthorization.sol";
      import "./interfaces/IVault.sol";
      /**
       * @dev To reduce the bytecode size of the Vault, most of the protocol fee logic is not here, but in the
       * ProtocolFeesCollector contract.
       */
      abstract contract Fees is IVault {
          using SafeERC20 for IERC20;
          ProtocolFeesCollector private immutable _protocolFeesCollector;
          constructor() {
              _protocolFeesCollector = new ProtocolFeesCollector(IVault(this));
          }
          function getProtocolFeesCollector() public view override returns (ProtocolFeesCollector) {
              return _protocolFeesCollector;
          }
          /**
           * @dev Returns the protocol swap fee percentage.
           */
          function _getProtocolSwapFeePercentage() internal view returns (uint256) {
              return getProtocolFeesCollector().getSwapFeePercentage();
          }
          /**
           * @dev Returns the protocol fee amount to charge for a flash loan of `amount`.
           */
          function _calculateFlashLoanFeeAmount(uint256 amount) internal view returns (uint256) {
              // Fixed point multiplication introduces error: we round up, which means in certain scenarios the charged
              // percentage can be slightly higher than intended.
              uint256 percentage = getProtocolFeesCollector().getFlashLoanFeePercentage();
              return FixedPoint.mulUp(amount, percentage);
          }
          function _payFeeAmount(IERC20 token, uint256 amount) internal {
              if (amount > 0) {
                  token.safeTransfer(address(getProtocolFeesCollector()), amount);
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "./LogExpMath.sol";
      import "../helpers/BalancerErrors.sol";
      /* solhint-disable private-vars-leading-underscore */
      library FixedPoint {
          uint256 internal constant ONE = 1e18; // 18 decimal places
          uint256 internal constant MAX_POW_RELATIVE_ERROR = 10000; // 10^(-14)
          // Minimum base for the power function when the exponent is 'free' (larger than ONE).
          uint256 internal constant MIN_POW_BASE_FREE_EXPONENT = 0.7e18;
          function add(uint256 a, uint256 b) internal pure returns (uint256) {
              // Fixed Point addition is the same as regular checked addition
              uint256 c = a + b;
              _require(c >= a, Errors.ADD_OVERFLOW);
              return c;
          }
          function sub(uint256 a, uint256 b) internal pure returns (uint256) {
              // Fixed Point addition is the same as regular checked addition
              _require(b <= a, Errors.SUB_OVERFLOW);
              uint256 c = a - b;
              return c;
          }
          function mulDown(uint256 a, uint256 b) internal pure returns (uint256) {
              uint256 product = a * b;
              _require(a == 0 || product / a == b, Errors.MUL_OVERFLOW);
              return product / ONE;
          }
          function mulUp(uint256 a, uint256 b) internal pure returns (uint256) {
              uint256 product = a * b;
              _require(a == 0 || product / a == b, Errors.MUL_OVERFLOW);
              if (product == 0) {
                  return 0;
              } else {
                  // The traditional divUp formula is:
                  // divUp(x, y) := (x + y - 1) / y
                  // To avoid intermediate overflow in the addition, we distribute the division and get:
                  // divUp(x, y) := (x - 1) / y + 1
                  // Note that this requires x != 0, which we already tested for.
                  return ((product - 1) / ONE) + 1;
              }
          }
          function divDown(uint256 a, uint256 b) internal pure returns (uint256) {
              _require(b != 0, Errors.ZERO_DIVISION);
              if (a == 0) {
                  return 0;
              } else {
                  uint256 aInflated = a * ONE;
                  _require(aInflated / a == ONE, Errors.DIV_INTERNAL); // mul overflow
                  return aInflated / b;
              }
          }
          function divUp(uint256 a, uint256 b) internal pure returns (uint256) {
              _require(b != 0, Errors.ZERO_DIVISION);
              if (a == 0) {
                  return 0;
              } else {
                  uint256 aInflated = a * ONE;
                  _require(aInflated / a == ONE, Errors.DIV_INTERNAL); // mul overflow
                  // The traditional divUp formula is:
                  // divUp(x, y) := (x + y - 1) / y
                  // To avoid intermediate overflow in the addition, we distribute the division and get:
                  // divUp(x, y) := (x - 1) / y + 1
                  // Note that this requires x != 0, which we already tested for.
                  return ((aInflated - 1) / b) + 1;
              }
          }
          /**
           * @dev Returns x^y, assuming both are fixed point numbers, rounding down. The result is guaranteed to not be above
           * the true value (that is, the error function expected - actual is always positive).
           */
          function powDown(uint256 x, uint256 y) internal pure returns (uint256) {
              uint256 raw = LogExpMath.pow(x, y);
              uint256 maxError = add(mulUp(raw, MAX_POW_RELATIVE_ERROR), 1);
              if (raw < maxError) {
                  return 0;
              } else {
                  return sub(raw, maxError);
              }
          }
          /**
           * @dev Returns x^y, assuming both are fixed point numbers, rounding up. The result is guaranteed to not be below
           * the true value (that is, the error function expected - actual is always negative).
           */
          function powUp(uint256 x, uint256 y) internal pure returns (uint256) {
              uint256 raw = LogExpMath.pow(x, y);
              uint256 maxError = add(mulUp(raw, MAX_POW_RELATIVE_ERROR), 1);
              return add(raw, maxError);
          }
          /**
           * @dev Returns the complement of a value (1 - x), capped to 0 if x is larger than 1.
           *
           * Useful when computing the complement for values with some level of relative error, as it strips this error and
           * prevents intermediate negative values.
           */
          function complement(uint256 x) internal pure returns (uint256) {
              return (x < ONE) ? (ONE - x) : 0;
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General internal License for more details.
      // You should have received a copy of the GNU General internal License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "../helpers/BalancerErrors.sol";
      /* solhint-disable */
      /**
       * @dev Exponentiation and logarithm functions for 18 decimal fixed point numbers (both base and exponent/argument).
       *
       * Exponentiation and logarithm with arbitrary bases (x^y and log_x(y)) are implemented by conversion to natural
       * exponentiation and logarithm (where the base is Euler's number).
       *
       * @author Fernando Martinelli - @fernandomartinelli
       * @author Sergio Yuhjtman - @sergioyuhjtman
       * @author Daniel Fernandez - @dmf7z
       */
      library LogExpMath {
          // All fixed point multiplications and divisions are inlined. This means we need to divide by ONE when multiplying
          // two numbers, and multiply by ONE when dividing them.
          // All arguments and return values are 18 decimal fixed point numbers.
          int256 constant ONE_18 = 1e18;
          // Internally, intermediate values are computed with higher precision as 20 decimal fixed point numbers, and in the
          // case of ln36, 36 decimals.
          int256 constant ONE_20 = 1e20;
          int256 constant ONE_36 = 1e36;
          // The domain of natural exponentiation is bound by the word size and number of decimals used.
          //
          // Because internally the result will be stored using 20 decimals, the largest possible result is
          // (2^255 - 1) / 10^20, which makes the largest exponent ln((2^255 - 1) / 10^20) = 130.700829182905140221.
          // The smallest possible result is 10^(-18), which makes largest negative argument
          // ln(10^(-18)) = -41.446531673892822312.
          // We use 130.0 and -41.0 to have some safety margin.
          int256 constant MAX_NATURAL_EXPONENT = 130e18;
          int256 constant MIN_NATURAL_EXPONENT = -41e18;
          // Bounds for ln_36's argument. Both ln(0.9) and ln(1.1) can be represented with 36 decimal places in a fixed point
          // 256 bit integer.
          int256 constant LN_36_LOWER_BOUND = ONE_18 - 1e17;
          int256 constant LN_36_UPPER_BOUND = ONE_18 + 1e17;
          uint256 constant MILD_EXPONENT_BOUND = 2**254 / uint256(ONE_20);
          // 18 decimal constants
          int256 constant x0 = 128000000000000000000; // 2ˆ7
          int256 constant a0 = 38877084059945950922200000000000000000000000000000000000; // eˆ(x0) (no decimals)
          int256 constant x1 = 64000000000000000000; // 2ˆ6
          int256 constant a1 = 6235149080811616882910000000; // eˆ(x1) (no decimals)
          // 20 decimal constants
          int256 constant x2 = 3200000000000000000000; // 2ˆ5
          int256 constant a2 = 7896296018268069516100000000000000; // eˆ(x2)
          int256 constant x3 = 1600000000000000000000; // 2ˆ4
          int256 constant a3 = 888611052050787263676000000; // eˆ(x3)
          int256 constant x4 = 800000000000000000000; // 2ˆ3
          int256 constant a4 = 298095798704172827474000; // eˆ(x4)
          int256 constant x5 = 400000000000000000000; // 2ˆ2
          int256 constant a5 = 5459815003314423907810; // eˆ(x5)
          int256 constant x6 = 200000000000000000000; // 2ˆ1
          int256 constant a6 = 738905609893065022723; // eˆ(x6)
          int256 constant x7 = 100000000000000000000; // 2ˆ0
          int256 constant a7 = 271828182845904523536; // eˆ(x7)
          int256 constant x8 = 50000000000000000000; // 2ˆ-1
          int256 constant a8 = 164872127070012814685; // eˆ(x8)
          int256 constant x9 = 25000000000000000000; // 2ˆ-2
          int256 constant a9 = 128402541668774148407; // eˆ(x9)
          int256 constant x10 = 12500000000000000000; // 2ˆ-3
          int256 constant a10 = 113314845306682631683; // eˆ(x10)
          int256 constant x11 = 6250000000000000000; // 2ˆ-4
          int256 constant a11 = 106449445891785942956; // eˆ(x11)
          /**
           * @dev Exponentiation (x^y) with unsigned 18 decimal fixed point base and exponent.
           *
           * Reverts if ln(x) * y is smaller than `MIN_NATURAL_EXPONENT`, or larger than `MAX_NATURAL_EXPONENT`.
           */
          function pow(uint256 x, uint256 y) internal pure returns (uint256) {
              if (y == 0) {
                  // We solve the 0^0 indetermination by making it equal one.
                  return uint256(ONE_18);
              }
              if (x == 0) {
                  return 0;
              }
              // Instead of computing x^y directly, we instead rely on the properties of logarithms and exponentiation to
              // arrive at that result. In particular, exp(ln(x)) = x, and ln(x^y) = y * ln(x). This means
              // x^y = exp(y * ln(x)).
              // The ln function takes a signed value, so we need to make sure x fits in the signed 256 bit range.
              _require(x < 2**255, Errors.X_OUT_OF_BOUNDS);
              int256 x_int256 = int256(x);
              // We will compute y * ln(x) in a single step. Depending on the value of x, we can either use ln or ln_36. In
              // both cases, we leave the division by ONE_18 (due to fixed point multiplication) to the end.
              // This prevents y * ln(x) from overflowing, and at the same time guarantees y fits in the signed 256 bit range.
              _require(y < MILD_EXPONENT_BOUND, Errors.Y_OUT_OF_BOUNDS);
              int256 y_int256 = int256(y);
              int256 logx_times_y;
              if (LN_36_LOWER_BOUND < x_int256 && x_int256 < LN_36_UPPER_BOUND) {
                  int256 ln_36_x = ln_36(x_int256);
                  // ln_36_x has 36 decimal places, so multiplying by y_int256 isn't as straightforward, since we can't just
                  // bring y_int256 to 36 decimal places, as it might overflow. Instead, we perform two 18 decimal
                  // multiplications and add the results: one with the first 18 decimals of ln_36_x, and one with the
                  // (downscaled) last 18 decimals.
                  logx_times_y = ((ln_36_x / ONE_18) * y_int256 + ((ln_36_x % ONE_18) * y_int256) / ONE_18);
              } else {
                  logx_times_y = ln(x_int256) * y_int256;
              }
              logx_times_y /= ONE_18;
              // Finally, we compute exp(y * ln(x)) to arrive at x^y
              _require(
                  MIN_NATURAL_EXPONENT <= logx_times_y && logx_times_y <= MAX_NATURAL_EXPONENT,
                  Errors.PRODUCT_OUT_OF_BOUNDS
              );
              return uint256(exp(logx_times_y));
          }
          /**
           * @dev Natural exponentiation (e^x) with signed 18 decimal fixed point exponent.
           *
           * Reverts if `x` is smaller than MIN_NATURAL_EXPONENT, or larger than `MAX_NATURAL_EXPONENT`.
           */
          function exp(int256 x) internal pure returns (int256) {
              _require(x >= MIN_NATURAL_EXPONENT && x <= MAX_NATURAL_EXPONENT, Errors.INVALID_EXPONENT);
              if (x < 0) {
                  // We only handle positive exponents: e^(-x) is computed as 1 / e^x. We can safely make x positive since it
                  // fits in the signed 256 bit range (as it is larger than MIN_NATURAL_EXPONENT).
                  // Fixed point division requires multiplying by ONE_18.
                  return ((ONE_18 * ONE_18) / exp(-x));
              }
              // First, we use the fact that e^(x+y) = e^x * e^y to decompose x into a sum of powers of two, which we call x_n,
              // where x_n == 2^(7 - n), and e^x_n = a_n has been precomputed. We choose the first x_n, x0, to equal 2^7
              // because all larger powers are larger than MAX_NATURAL_EXPONENT, and therefore not present in the
              // decomposition.
              // At the end of this process we will have the product of all e^x_n = a_n that apply, and the remainder of this
              // decomposition, which will be lower than the smallest x_n.
              // exp(x) = k_0 * a_0 * k_1 * a_1 * ... + k_n * a_n * exp(remainder), where each k_n equals either 0 or 1.
              // We mutate x by subtracting x_n, making it the remainder of the decomposition.
              // The first two a_n (e^(2^7) and e^(2^6)) are too large if stored as 18 decimal numbers, and could cause
              // intermediate overflows. Instead we store them as plain integers, with 0 decimals.
              // Additionally, x0 + x1 is larger than MAX_NATURAL_EXPONENT, which means they will not both be present in the
              // decomposition.
              // For each x_n, we test if that term is present in the decomposition (if x is larger than it), and if so deduct
              // it and compute the accumulated product.
              int256 firstAN;
              if (x >= x0) {
                  x -= x0;
                  firstAN = a0;
              } else if (x >= x1) {
                  x -= x1;
                  firstAN = a1;
              } else {
                  firstAN = 1; // One with no decimal places
              }
              // We now transform x into a 20 decimal fixed point number, to have enhanced precision when computing the
              // smaller terms.
              x *= 100;
              // `product` is the accumulated product of all a_n (except a0 and a1), which starts at 20 decimal fixed point
              // one. Recall that fixed point multiplication requires dividing by ONE_20.
              int256 product = ONE_20;
              if (x >= x2) {
                  x -= x2;
                  product = (product * a2) / ONE_20;
              }
              if (x >= x3) {
                  x -= x3;
                  product = (product * a3) / ONE_20;
              }
              if (x >= x4) {
                  x -= x4;
                  product = (product * a4) / ONE_20;
              }
              if (x >= x5) {
                  x -= x5;
                  product = (product * a5) / ONE_20;
              }
              if (x >= x6) {
                  x -= x6;
                  product = (product * a6) / ONE_20;
              }
              if (x >= x7) {
                  x -= x7;
                  product = (product * a7) / ONE_20;
              }
              if (x >= x8) {
                  x -= x8;
                  product = (product * a8) / ONE_20;
              }
              if (x >= x9) {
                  x -= x9;
                  product = (product * a9) / ONE_20;
              }
              // x10 and x11 are unnecessary here since we have high enough precision already.
              // Now we need to compute e^x, where x is small (in particular, it is smaller than x9). We use the Taylor series
              // expansion for e^x: 1 + x + (x^2 / 2!) + (x^3 / 3!) + ... + (x^n / n!).
              int256 seriesSum = ONE_20; // The initial one in the sum, with 20 decimal places.
              int256 term; // Each term in the sum, where the nth term is (x^n / n!).
              // The first term is simply x.
              term = x;
              seriesSum += term;
              // Each term (x^n / n!) equals the previous one times x, divided by n. Since x is a fixed point number,
              // multiplying by it requires dividing by ONE_20, but dividing by the non-fixed point n values does not.
              term = ((term * x) / ONE_20) / 2;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 3;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 4;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 5;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 6;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 7;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 8;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 9;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 10;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 11;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 12;
              seriesSum += term;
              // 12 Taylor terms are sufficient for 18 decimal precision.
              // We now have the first a_n (with no decimals), and the product of all other a_n present, and the Taylor
              // approximation of the exponentiation of the remainder (both with 20 decimals). All that remains is to multiply
              // all three (one 20 decimal fixed point multiplication, dividing by ONE_20, and one integer multiplication),
              // and then drop two digits to return an 18 decimal value.
              return (((product * seriesSum) / ONE_20) * firstAN) / 100;
          }
          /**
           * @dev Natural logarithm (ln(a)) with signed 18 decimal fixed point argument.
           */
          function ln(int256 a) internal pure returns (int256) {
              // The real natural logarithm is not defined for negative numbers or zero.
              _require(a > 0, Errors.OUT_OF_BOUNDS);
              if (a < ONE_18) {
                  // Since ln(a^k) = k * ln(a), we can compute ln(a) as ln(a) = ln((1/a)^(-1)) = - ln((1/a)). If a is less
                  // than one, 1/a will be greater than one, and this if statement will not be entered in the recursive call.
                  // Fixed point division requires multiplying by ONE_18.
                  return (-ln((ONE_18 * ONE_18) / a));
              }
              // First, we use the fact that ln^(a * b) = ln(a) + ln(b) to decompose ln(a) into a sum of powers of two, which
              // we call x_n, where x_n == 2^(7 - n), which are the natural logarithm of precomputed quantities a_n (that is,
              // ln(a_n) = x_n). We choose the first x_n, x0, to equal 2^7 because the exponential of all larger powers cannot
              // be represented as 18 fixed point decimal numbers in 256 bits, and are therefore larger than a.
              // At the end of this process we will have the sum of all x_n = ln(a_n) that apply, and the remainder of this
              // decomposition, which will be lower than the smallest a_n.
              // ln(a) = k_0 * x_0 + k_1 * x_1 + ... + k_n * x_n + ln(remainder), where each k_n equals either 0 or 1.
              // We mutate a by subtracting a_n, making it the remainder of the decomposition.
              // For reasons related to how `exp` works, the first two a_n (e^(2^7) and e^(2^6)) are not stored as fixed point
              // numbers with 18 decimals, but instead as plain integers with 0 decimals, so we need to multiply them by
              // ONE_18 to convert them to fixed point.
              // For each a_n, we test if that term is present in the decomposition (if a is larger than it), and if so divide
              // by it and compute the accumulated sum.
              int256 sum = 0;
              if (a >= a0 * ONE_18) {
                  a /= a0; // Integer, not fixed point division
                  sum += x0;
              }
              if (a >= a1 * ONE_18) {
                  a /= a1; // Integer, not fixed point division
                  sum += x1;
              }
              // All other a_n and x_n are stored as 20 digit fixed point numbers, so we convert the sum and a to this format.
              sum *= 100;
              a *= 100;
              // Because further a_n are  20 digit fixed point numbers, we multiply by ONE_20 when dividing by them.
              if (a >= a2) {
                  a = (a * ONE_20) / a2;
                  sum += x2;
              }
              if (a >= a3) {
                  a = (a * ONE_20) / a3;
                  sum += x3;
              }
              if (a >= a4) {
                  a = (a * ONE_20) / a4;
                  sum += x4;
              }
              if (a >= a5) {
                  a = (a * ONE_20) / a5;
                  sum += x5;
              }
              if (a >= a6) {
                  a = (a * ONE_20) / a6;
                  sum += x6;
              }
              if (a >= a7) {
                  a = (a * ONE_20) / a7;
                  sum += x7;
              }
              if (a >= a8) {
                  a = (a * ONE_20) / a8;
                  sum += x8;
              }
              if (a >= a9) {
                  a = (a * ONE_20) / a9;
                  sum += x9;
              }
              if (a >= a10) {
                  a = (a * ONE_20) / a10;
                  sum += x10;
              }
              if (a >= a11) {
                  a = (a * ONE_20) / a11;
                  sum += x11;
              }
              // a is now a small number (smaller than a_11, which roughly equals 1.06). This means we can use a Taylor series
              // that converges rapidly for values of `a` close to one - the same one used in ln_36.
              // Let z = (a - 1) / (a + 1).
              // ln(a) = 2 * (z + z^3 / 3 + z^5 / 5 + z^7 / 7 + ... + z^(2 * n + 1) / (2 * n + 1))
              // Recall that 20 digit fixed point division requires multiplying by ONE_20, and multiplication requires
              // division by ONE_20.
              int256 z = ((a - ONE_20) * ONE_20) / (a + ONE_20);
              int256 z_squared = (z * z) / ONE_20;
              // num is the numerator of the series: the z^(2 * n + 1) term
              int256 num = z;
              // seriesSum holds the accumulated sum of each term in the series, starting with the initial z
              int256 seriesSum = num;
              // In each step, the numerator is multiplied by z^2
              num = (num * z_squared) / ONE_20;
              seriesSum += num / 3;
              num = (num * z_squared) / ONE_20;
              seriesSum += num / 5;
              num = (num * z_squared) / ONE_20;
              seriesSum += num / 7;
              num = (num * z_squared) / ONE_20;
              seriesSum += num / 9;
              num = (num * z_squared) / ONE_20;
              seriesSum += num / 11;
              // 6 Taylor terms are sufficient for 36 decimal precision.
              // Finally, we multiply by 2 (non fixed point) to compute ln(remainder)
              seriesSum *= 2;
              // We now have the sum of all x_n present, and the Taylor approximation of the logarithm of the remainder (both
              // with 20 decimals). All that remains is to sum these two, and then drop two digits to return a 18 decimal
              // value.
              return (sum + seriesSum) / 100;
          }
          /**
           * @dev Logarithm (log(arg, base), with signed 18 decimal fixed point base and argument argument.
           */
          function log(int256 arg, int256 base) internal pure returns (int256) {
              // This performs a simple base change: log(arg, base) = ln(arg) / ln(base).
              // Both logBase and logArg are computed as 36 decimal fixed point numbers, either by using ln_36, or by
              // upscaling.
              int256 logBase;
              if (LN_36_LOWER_BOUND < base && base < LN_36_UPPER_BOUND) {
                  logBase = ln_36(base);
              } else {
                  logBase = ln(base) * ONE_18;
              }
              int256 logArg;
              if (LN_36_LOWER_BOUND < arg && arg < LN_36_UPPER_BOUND) {
                  logArg = ln_36(arg);
              } else {
                  logArg = ln(arg) * ONE_18;
              }
              // When dividing, we multiply by ONE_18 to arrive at a result with 18 decimal places
              return (logArg * ONE_18) / logBase;
          }
          /**
           * @dev High precision (36 decimal places) natural logarithm (ln(x)) with signed 18 decimal fixed point argument,
           * for x close to one.
           *
           * Should only be used if x is between LN_36_LOWER_BOUND and LN_36_UPPER_BOUND.
           */
          function ln_36(int256 x) private pure returns (int256) {
              // Since ln(1) = 0, a value of x close to one will yield a very small result, which makes using 36 digits
              // worthwhile.
              // First, we transform x to a 36 digit fixed point value.
              x *= ONE_18;
              // We will use the following Taylor expansion, which converges very rapidly. Let z = (x - 1) / (x + 1).
              // ln(x) = 2 * (z + z^3 / 3 + z^5 / 5 + z^7 / 7 + ... + z^(2 * n + 1) / (2 * n + 1))
              // Recall that 36 digit fixed point division requires multiplying by ONE_36, and multiplication requires
              // division by ONE_36.
              int256 z = ((x - ONE_36) * ONE_36) / (x + ONE_36);
              int256 z_squared = (z * z) / ONE_36;
              // num is the numerator of the series: the z^(2 * n + 1) term
              int256 num = z;
              // seriesSum holds the accumulated sum of each term in the series, starting with the initial z
              int256 seriesSum = num;
              // In each step, the numerator is multiplied by z^2
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 3;
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 5;
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 7;
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 9;
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 11;
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 13;
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 15;
              // 8 Taylor terms are sufficient for 36 decimal precision.
              // All that remains is multiplying by 2 (non fixed point).
              return seriesSum * 2;
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      import "../helpers/BalancerErrors.sol";
      /**
       * @dev Wrappers over Solidity's arithmetic operations with added overflow checks.
       * Adapted from OpenZeppelin's SafeMath library
       */
      library Math {
          /**
           * @dev Returns the addition of two unsigned integers of 256 bits, reverting on overflow.
           */
          function add(uint256 a, uint256 b) internal pure returns (uint256) {
              uint256 c = a + b;
              _require(c >= a, Errors.ADD_OVERFLOW);
              return c;
          }
          /**
           * @dev Returns the addition of two signed integers, reverting on overflow.
           */
          function add(int256 a, int256 b) internal pure returns (int256) {
              int256 c = a + b;
              _require((b >= 0 && c >= a) || (b < 0 && c < a), Errors.ADD_OVERFLOW);
              return c;
          }
          /**
           * @dev Returns the subtraction of two unsigned integers of 256 bits, reverting on overflow.
           */
          function sub(uint256 a, uint256 b) internal pure returns (uint256) {
              _require(b <= a, Errors.SUB_OVERFLOW);
              uint256 c = a - b;
              return c;
          }
          /**
           * @dev Returns the subtraction of two signed integers, reverting on overflow.
           */
          function sub(int256 a, int256 b) internal pure returns (int256) {
              int256 c = a - b;
              _require((b >= 0 && c <= a) || (b < 0 && c > a), Errors.SUB_OVERFLOW);
              return c;
          }
          /**
           * @dev Returns the largest of two numbers of 256 bits.
           */
          function max(uint256 a, uint256 b) internal pure returns (uint256) {
              return a >= b ? a : b;
          }
          /**
           * @dev Returns the smallest of two numbers of 256 bits.
           */
          function min(uint256 a, uint256 b) internal pure returns (uint256) {
              return a < b ? a : b;
          }
          function mul(uint256 a, uint256 b) internal pure returns (uint256) {
              uint256 c = a * b;
              _require(a == 0 || c / a == b, Errors.MUL_OVERFLOW);
              return c;
          }
          function divDown(uint256 a, uint256 b) internal pure returns (uint256) {
              _require(b != 0, Errors.ZERO_DIVISION);
              return a / b;
          }
          function divUp(uint256 a, uint256 b) internal pure returns (uint256) {
              _require(b != 0, Errors.ZERO_DIVISION);
              if (a == 0) {
                  return 0;
              } else {
                  return 1 + (a - 1) / b;
              }
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      // Based on the EnumerableMap library from OpenZeppelin contracts, altered to include the following:
      //  * a map from IERC20 to bytes32
      //  * entries are stored in mappings instead of arrays, reducing implicit storage reads for out-of-bounds checks
      //  * unchecked_at and unchecked_valueAt, which allow for more gas efficient data reads in some scenarios
      //  * unchecked_indexOf and unchecked_setAt, which allow for more gas efficient data writes in some scenarios
      //
      // Additionally, the base private functions that work on bytes32 were removed and replaced with a native implementation
      // for IERC20 keys, to reduce bytecode size and runtime costs.
      // We're using non-standard casing for the unchecked functions to differentiate them, so we need to turn off that rule
      // solhint-disable func-name-mixedcase
      import "./IERC20.sol";
      import "../helpers/BalancerErrors.sol";
      /**
       * @dev Library for managing an enumerable variant of Solidity's
       * https://solidity.readthedocs.io/en/latest/types.html#mapping-types[`mapping`]
       * type.
       *
       * Maps have the following properties:
       *
       * - Entries are added, removed, and checked for existence in constant time
       * (O(1)).
       * - Entries are enumerated in O(n). No guarantees are made on the ordering.
       *
       * ```
       * contract Example {
       *     // Add the library methods
       *     using EnumerableMap for EnumerableMap.UintToAddressMap;
       *
       *     // Declare a set state variable
       *     EnumerableMap.UintToAddressMap private myMap;
       * }
       * ```
       */
      library EnumerableMap {
          // The original OpenZeppelin implementation uses a generic Map type with bytes32 keys: this was replaced with
          // IERC20ToBytes32Map, which uses IERC20 keys natively, resulting in more dense bytecode.
          struct IERC20ToBytes32MapEntry {
              IERC20 _key;
              bytes32 _value;
          }
          struct IERC20ToBytes32Map {
              // Number of entries in the map
              uint256 _length;
              // Storage of map keys and values
              mapping(uint256 => IERC20ToBytes32MapEntry) _entries;
              // Position of the entry defined by a key in the `entries` array, plus 1
              // because index 0 means a key is not in the map.
              mapping(IERC20 => uint256) _indexes;
          }
          /**
           * @dev Adds a key-value pair to a map, or updates the value for an existing
           * key. O(1).
           *
           * Returns true if the key was added to the map, that is if it was not
           * already present.
           */
          function set(
              IERC20ToBytes32Map storage map,
              IERC20 key,
              bytes32 value
          ) internal returns (bool) {
              // We read and store the key's index to prevent multiple reads from the same storage slot
              uint256 keyIndex = map._indexes[key];
              // Equivalent to !contains(map, key)
              if (keyIndex == 0) {
                  uint256 previousLength = map._length;
                  map._entries[previousLength] = IERC20ToBytes32MapEntry({ _key: key, _value: value });
                  map._length = previousLength + 1;
                  // The entry is stored at previousLength, but we add 1 to all indexes
                  // and use 0 as a sentinel value
                  map._indexes[key] = previousLength + 1;
                  return true;
              } else {
                  map._entries[keyIndex - 1]._value = value;
                  return false;
              }
          }
          /**
           * @dev Updates the value for an entry, given its key's index. The key index can be retrieved via
           * {unchecked_indexOf}, and it should be noted that key indices may change when calling {set} or {remove}. O(1).
           *
           * This function performs one less storage read than {set}, but it should only be used when `index` is known to be
           * within bounds.
           */
          function unchecked_setAt(
              IERC20ToBytes32Map storage map,
              uint256 index,
              bytes32 value
          ) internal {
              map._entries[index]._value = value;
          }
          /**
           * @dev Removes a key-value pair from a map. O(1).
           *
           * Returns true if the key was removed from the map, that is if it was present.
           */
          function remove(IERC20ToBytes32Map storage map, IERC20 key) internal returns (bool) {
              // We read and store the key's index to prevent multiple reads from the same storage slot
              uint256 keyIndex = map._indexes[key];
              // Equivalent to contains(map, key)
              if (keyIndex != 0) {
                  // To delete a key-value pair from the _entries pseudo-array in O(1), we swap the entry to delete with the
                  // one at the highest index, and then remove this last entry (sometimes called as 'swap and pop').
                  // This modifies the order of the pseudo-array, as noted in {at}.
                  uint256 toDeleteIndex = keyIndex - 1;
                  uint256 lastIndex = map._length - 1;
                  // When the entry to delete is the last one, the swap operation is unnecessary. However, since this occurs
                  // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.
                  IERC20ToBytes32MapEntry storage lastEntry = map._entries[lastIndex];
                  // Move the last entry to the index where the entry to delete is
                  map._entries[toDeleteIndex] = lastEntry;
                  // Update the index for the moved entry
                  map._indexes[lastEntry._key] = toDeleteIndex + 1; // All indexes are 1-based
                  // Delete the slot where the moved entry was stored
                  delete map._entries[lastIndex];
                  map._length = lastIndex;
                  // Delete the index for the deleted slot
                  delete map._indexes[key];
                  return true;
              } else {
                  return false;
              }
          }
          /**
           * @dev Returns true if the key is in the map. O(1).
           */
          function contains(IERC20ToBytes32Map storage map, IERC20 key) internal view returns (bool) {
              return map._indexes[key] != 0;
          }
          /**
           * @dev Returns the number of key-value pairs in the map. O(1).
           */
          function length(IERC20ToBytes32Map storage map) internal view returns (uint256) {
              return map._length;
          }
          /**
           * @dev Returns the key-value pair stored at position `index` in the map. O(1).
           *
           * Note that there are no guarantees on the ordering of entries inside the
           * array, and it may change when more entries are added or removed.
           *
           * Requirements:
           *
           * - `index` must be strictly less than {length}.
           */
          function at(IERC20ToBytes32Map storage map, uint256 index) internal view returns (IERC20, bytes32) {
              _require(map._length > index, Errors.OUT_OF_BOUNDS);
              return unchecked_at(map, index);
          }
          /**
           * @dev Same as {at}, except this doesn't revert if `index` it outside of the map (i.e. if it is equal or larger
           * than {length}). O(1).
           *
           * This function performs one less storage read than {at}, but should only be used when `index` is known to be
           * within bounds.
           */
          function unchecked_at(IERC20ToBytes32Map storage map, uint256 index) internal view returns (IERC20, bytes32) {
              IERC20ToBytes32MapEntry storage entry = map._entries[index];
              return (entry._key, entry._value);
          }
          /**
           * @dev Same as {unchecked_At}, except it only returns the value and not the key (performing one less storage
           * read). O(1).
           */
          function unchecked_valueAt(IERC20ToBytes32Map storage map, uint256 index) internal view returns (bytes32) {
              return map._entries[index]._value;
          }
          /**
           * @dev Returns the value associated with `key`. O(1).
           *
           * Requirements:
           *
           * - `key` must be in the map. Reverts with `errorCode` otherwise.
           */
          function get(
              IERC20ToBytes32Map storage map,
              IERC20 key,
              uint256 errorCode
          ) internal view returns (bytes32) {
              uint256 index = map._indexes[key];
              _require(index > 0, errorCode);
              return unchecked_valueAt(map, index - 1);
          }
          /**
           * @dev Returns the index for `key` **plus one**. Does not revert if the key is not in the map, and returns 0
           * instead.
           */
          function unchecked_indexOf(IERC20ToBytes32Map storage map, IERC20 key) internal view returns (uint256) {
              return map._indexes[key];
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      import "../helpers/BalancerErrors.sol";
      // Based on the EnumerableSet library from OpenZeppelin contracts, altered to remove the base private functions that
      // work on bytes32, replacing them with a native implementation for address values, to reduce bytecode size and runtime
      // costs.
      // The `unchecked_at` function was also added, which allows for more gas efficient data reads in some scenarios.
      /**
       * @dev Library for managing
       * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
       * types.
       *
       * Sets have the following properties:
       *
       * - Elements are added, removed, and checked for existence in constant time
       * (O(1)).
       * - Elements are enumerated in O(n). No guarantees are made on the ordering.
       *
       * ```
       * contract Example {
       *     // Add the library methods
       *     using EnumerableSet for EnumerableSet.AddressSet;
       *
       *     // Declare a set state variable
       *     EnumerableSet.AddressSet private mySet;
       * }
       * ```
       *
       * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
       * and `uint256` (`UintSet`) are supported.
       */
      library EnumerableSet {
          // The original OpenZeppelin implementation uses a generic Set type with bytes32 values: this was replaced with
          // AddressSet, which uses address keys natively, resulting in more dense bytecode.
          struct AddressSet {
              // Storage of set values
              address[] _values;
              // Position of the value in the `values` array, plus 1 because index 0
              // means a value is not in the set.
              mapping(address => uint256) _indexes;
          }
          /**
           * @dev Add a value to a set. O(1).
           *
           * Returns true if the value was added to the set, that is if it was not
           * already present.
           */
          function add(AddressSet storage set, address value) internal returns (bool) {
              if (!contains(set, value)) {
                  set._values.push(value);
                  // The value is stored at length-1, but we add 1 to all indexes
                  // and use 0 as a sentinel value
                  set._indexes[value] = set._values.length;
                  return true;
              } else {
                  return false;
              }
          }
          /**
           * @dev Removes a value from a set. O(1).
           *
           * Returns true if the value was removed from the set, that is if it was
           * present.
           */
          function remove(AddressSet storage set, address value) internal returns (bool) {
              // We read and store the value's index to prevent multiple reads from the same storage slot
              uint256 valueIndex = set._indexes[value];
              if (valueIndex != 0) {
                  // Equivalent to contains(set, value)
                  // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
                  // the array, and then remove the last element (sometimes called as 'swap and pop').
                  // This modifies the order of the array, as noted in {at}.
                  uint256 toDeleteIndex = valueIndex - 1;
                  uint256 lastIndex = set._values.length - 1;
                  // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
                  // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.
                  address lastValue = set._values[lastIndex];
                  // Move the last value to the index where the value to delete is
                  set._values[toDeleteIndex] = lastValue;
                  // Update the index for the moved value
                  set._indexes[lastValue] = toDeleteIndex + 1; // All indexes are 1-based
                  // Delete the slot where the moved value was stored
                  set._values.pop();
                  // Delete the index for the deleted slot
                  delete set._indexes[value];
                  return true;
              } else {
                  return false;
              }
          }
          /**
           * @dev Returns true if the value is in the set. O(1).
           */
          function contains(AddressSet storage set, address value) internal view returns (bool) {
              return set._indexes[value] != 0;
          }
          /**
           * @dev Returns the number of values on the set. O(1).
           */
          function length(AddressSet storage set) internal view returns (uint256) {
              return set._values.length;
          }
          /**
           * @dev Returns the value stored at position `index` in the set. O(1).
           *
           * Note that there are no guarantees on the ordering of values inside the
           * array, and it may change when more values are added or removed.
           *
           * Requirements:
           *
           * - `index` must be strictly less than {length}.
           */
          function at(AddressSet storage set, uint256 index) internal view returns (address) {
              _require(set._values.length > index, Errors.OUT_OF_BOUNDS);
              return unchecked_at(set, index);
          }
          /**
           * @dev Same as {at}, except this doesn't revert if `index` it outside of the set (i.e. if it is equal or larger
           * than {length}). O(1).
           *
           * This function performs one less storage read than {at}, but should only be used when `index` is known to be
           * within bounds.
           */
          function unchecked_at(AddressSet storage set, uint256 index) internal view returns (address) {
              return set._values[index];
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      import "../helpers/BalancerErrors.sol";
      /**
       * @dev Wrappers over Solidity's uintXX/intXX casting operators with added overflow
       * checks.
       *
       * Downcasting from uint256/int256 in Solidity does not revert on overflow. This can
       * easily result in undesired exploitation or bugs, since developers usually
       * assume that overflows raise errors. `SafeCast` restores this intuition by
       * reverting the transaction when such an operation overflows.
       *
       * Using this library instead of the unchecked operations eliminates an entire
       * class of bugs, so it's recommended to use it always.
       *
       * Can be combined with {SafeMath} and {SignedSafeMath} to extend it to smaller types, by performing
       * all math on `uint256` and `int256` and then downcasting.
       */
      library SafeCast {
          /**
           * @dev Converts an unsigned uint256 into a signed int256.
           *
           * Requirements:
           *
           * - input must be less than or equal to maxInt256.
           */
          function toInt256(uint256 value) internal pure returns (int256) {
              _require(value < 2**255, Errors.SAFE_CAST_VALUE_CANT_FIT_INT256);
              return int256(value);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../lib/math/Math.sol";
      import "../lib/helpers/BalancerErrors.sol";
      import "../lib/helpers/InputHelpers.sol";
      import "../lib/openzeppelin/IERC20.sol";
      import "../lib/openzeppelin/ReentrancyGuard.sol";
      import "../lib/openzeppelin/SafeERC20.sol";
      import "./Fees.sol";
      import "./PoolTokens.sol";
      import "./UserBalance.sol";
      import "./interfaces/IBasePool.sol";
      /**
       * @dev Stores the Asset Managers (by Pool and token), and implements the top level Asset Manager and Pool interfaces,
       * such as registering and deregistering tokens, joining and exiting Pools, and informational functions like `getPool`
       * and `getPoolTokens`, delegating to specialization-specific functions as needed.
       *
       * `managePoolBalance` handles all Asset Manager interactions.
       */
      abstract contract PoolBalances is Fees, ReentrancyGuard, PoolTokens, UserBalance {
          using Math for uint256;
          using SafeERC20 for IERC20;
          using BalanceAllocation for bytes32;
          using BalanceAllocation for bytes32[];
          function joinPool(
              bytes32 poolId,
              address sender,
              address recipient,
              JoinPoolRequest memory request
          ) external payable override whenNotPaused {
              // This function doesn't have the nonReentrant modifier: it is applied to `_joinOrExit` instead.
              // Note that `recipient` is not actually payable in the context of a join - we cast it because we handle both
              // joins and exits at once.
              _joinOrExit(PoolBalanceChangeKind.JOIN, poolId, sender, payable(recipient), _toPoolBalanceChange(request));
          }
          function exitPool(
              bytes32 poolId,
              address sender,
              address payable recipient,
              ExitPoolRequest memory request
          ) external override {
              // This function doesn't have the nonReentrant modifier: it is applied to `_joinOrExit` instead.
              _joinOrExit(PoolBalanceChangeKind.EXIT, poolId, sender, recipient, _toPoolBalanceChange(request));
          }
          // This has the exact same layout as JoinPoolRequest and ExitPoolRequest, except the `maxAmountsIn` and
          // `minAmountsOut` are called `limits`. Internally we use this struct for both since these two functions are quite
          // similar, but expose the others to callers for clarity.
          struct PoolBalanceChange {
              IAsset[] assets;
              uint256[] limits;
              bytes userData;
              bool useInternalBalance;
          }
          /**
           * @dev Converts a JoinPoolRequest into a PoolBalanceChange, with no runtime cost.
           */
          function _toPoolBalanceChange(JoinPoolRequest memory request)
              private
              pure
              returns (PoolBalanceChange memory change)
          {
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  change := request
              }
          }
          /**
           * @dev Converts an ExitPoolRequest into a PoolBalanceChange, with no runtime cost.
           */
          function _toPoolBalanceChange(ExitPoolRequest memory request)
              private
              pure
              returns (PoolBalanceChange memory change)
          {
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  change := request
              }
          }
          /**
           * @dev Implements both `joinPool` and `exitPool`, based on `kind`.
           */
          function _joinOrExit(
              PoolBalanceChangeKind kind,
              bytes32 poolId,
              address sender,
              address payable recipient,
              PoolBalanceChange memory change
          ) private nonReentrant withRegisteredPool(poolId) authenticateFor(sender) {
              // This function uses a large number of stack variables (poolId, sender and recipient, balances, amounts, fees,
              // etc.), which leads to 'stack too deep' issues. It relies on private functions with seemingly arbitrary
              // interfaces to work around this limitation.
              InputHelpers.ensureInputLengthMatch(change.assets.length, change.limits.length);
              // We first check that the caller passed the Pool's registered tokens in the correct order, and retrieve the
              // current balance for each.
              IERC20[] memory tokens = _translateToIERC20(change.assets);
              bytes32[] memory balances = _validateTokensAndGetBalances(poolId, tokens);
              // The bulk of the work is done here: the corresponding Pool hook is called, its final balances are computed,
              // assets are transferred, and fees are paid.
              (
                  bytes32[] memory finalBalances,
                  uint256[] memory amountsInOrOut,
                  uint256[] memory paidProtocolSwapFeeAmounts
              ) = _callPoolBalanceChange(kind, poolId, sender, recipient, change, balances);
              // All that remains is storing the new Pool balances.
              PoolSpecialization specialization = _getPoolSpecialization(poolId);
              if (specialization == PoolSpecialization.TWO_TOKEN) {
                  _setTwoTokenPoolCashBalances(poolId, tokens[0], finalBalances[0], tokens[1], finalBalances[1]);
              } else if (specialization == PoolSpecialization.MINIMAL_SWAP_INFO) {
                  _setMinimalSwapInfoPoolBalances(poolId, tokens, finalBalances);
              } else {
                  // PoolSpecialization.GENERAL
                  _setGeneralPoolBalances(poolId, finalBalances);
              }
              bool positive = kind == PoolBalanceChangeKind.JOIN; // Amounts in are positive, out are negative
              emit PoolBalanceChanged(
                  poolId,
                  sender,
                  tokens,
                  // We can unsafely cast to int256 because balances are actually stored as uint112
                  _unsafeCastToInt256(amountsInOrOut, positive),
                  paidProtocolSwapFeeAmounts
              );
          }
          /**
           * @dev Calls the corresponding Pool hook to get the amounts in/out plus protocol fee amounts, and performs the
           * associated token transfers and fee payments, returning the Pool's final balances.
           */
          function _callPoolBalanceChange(
              PoolBalanceChangeKind kind,
              bytes32 poolId,
              address sender,
              address payable recipient,
              PoolBalanceChange memory change,
              bytes32[] memory balances
          )
              private
              returns (
                  bytes32[] memory finalBalances,
                  uint256[] memory amountsInOrOut,
                  uint256[] memory dueProtocolFeeAmounts
              )
          {
              (uint256[] memory totalBalances, uint256 lastChangeBlock) = balances.totalsAndLastChangeBlock();
              IBasePool pool = IBasePool(_getPoolAddress(poolId));
              (amountsInOrOut, dueProtocolFeeAmounts) = kind == PoolBalanceChangeKind.JOIN
                  ? pool.onJoinPool(
                      poolId,
                      sender,
                      recipient,
                      totalBalances,
                      lastChangeBlock,
                      _getProtocolSwapFeePercentage(),
                      change.userData
                  )
                  : pool.onExitPool(
                      poolId,
                      sender,
                      recipient,
                      totalBalances,
                      lastChangeBlock,
                      _getProtocolSwapFeePercentage(),
                      change.userData
                  );
              InputHelpers.ensureInputLengthMatch(balances.length, amountsInOrOut.length, dueProtocolFeeAmounts.length);
              // The Vault ignores the `recipient` in joins and the `sender` in exits: it is up to the Pool to keep track of
              // their participation.
              finalBalances = kind == PoolBalanceChangeKind.JOIN
                  ? _processJoinPoolTransfers(sender, change, balances, amountsInOrOut, dueProtocolFeeAmounts)
                  : _processExitPoolTransfers(recipient, change, balances, amountsInOrOut, dueProtocolFeeAmounts);
          }
          /**
           * @dev Transfers `amountsIn` from `sender`, checking that they are within their accepted limits, and pays
           * accumulated protocol swap fees.
           *
           * Returns the Pool's final balances, which are the current balances plus `amountsIn` minus accumulated protocol
           * swap fees.
           */
          function _processJoinPoolTransfers(
              address sender,
              PoolBalanceChange memory change,
              bytes32[] memory balances,
              uint256[] memory amountsIn,
              uint256[] memory dueProtocolFeeAmounts
          ) private returns (bytes32[] memory finalBalances) {
              // We need to track how much of the received ETH was used and wrapped into WETH to return any excess.
              uint256 wrappedEth = 0;
              finalBalances = new bytes32[](balances.length);
              for (uint256 i = 0; i < change.assets.length; ++i) {
                  uint256 amountIn = amountsIn[i];
                  _require(amountIn <= change.limits[i], Errors.JOIN_ABOVE_MAX);
                  // Receive assets from the sender - possibly from Internal Balance.
                  IAsset asset = change.assets[i];
                  _receiveAsset(asset, amountIn, sender, change.useInternalBalance);
                  if (_isETH(asset)) {
                      wrappedEth = wrappedEth.add(amountIn);
                  }
                  uint256 feeAmount = dueProtocolFeeAmounts[i];
                  _payFeeAmount(_translateToIERC20(asset), feeAmount);
                  // Compute the new Pool balances. Note that the fee amount might be larger than `amountIn`,
                  // resulting in an overall decrease of the Pool's balance for a token.
                  finalBalances[i] = (amountIn >= feeAmount) // This lets us skip checked arithmetic
                      ? balances[i].increaseCash(amountIn - feeAmount)
                      : balances[i].decreaseCash(feeAmount - amountIn);
              }
              // Handle any used and remaining ETH.
              _handleRemainingEth(wrappedEth);
          }
          /**
           * @dev Transfers `amountsOut` to `recipient`, checking that they are within their accepted limits, and pays
           * accumulated protocol swap fees from the Pool.
           *
           * Returns the Pool's final balances, which are the current `balances` minus `amountsOut` and fees paid
           * (`dueProtocolFeeAmounts`).
           */
          function _processExitPoolTransfers(
              address payable recipient,
              PoolBalanceChange memory change,
              bytes32[] memory balances,
              uint256[] memory amountsOut,
              uint256[] memory dueProtocolFeeAmounts
          ) private returns (bytes32[] memory finalBalances) {
              finalBalances = new bytes32[](balances.length);
              for (uint256 i = 0; i < change.assets.length; ++i) {
                  uint256 amountOut = amountsOut[i];
                  _require(amountOut >= change.limits[i], Errors.EXIT_BELOW_MIN);
                  // Send tokens to the recipient - possibly to Internal Balance
                  IAsset asset = change.assets[i];
                  _sendAsset(asset, amountOut, recipient, change.useInternalBalance);
                  uint256 feeAmount = dueProtocolFeeAmounts[i];
                  _payFeeAmount(_translateToIERC20(asset), feeAmount);
                  // Compute the new Pool balances. A Pool's token balance always decreases after an exit (potentially by 0).
                  finalBalances[i] = balances[i].decreaseCash(amountOut.add(feeAmount));
              }
          }
          /**
           * @dev Returns the total balance for `poolId`'s `expectedTokens`.
           *
           * `expectedTokens` must exactly equal the token array returned by `getPoolTokens`: both arrays must have the same
           * length, elements and order. Additionally, the Pool must have at least one registered token.
           */
          function _validateTokensAndGetBalances(bytes32 poolId, IERC20[] memory expectedTokens)
              private
              view
              returns (bytes32[] memory)
          {
              (IERC20[] memory actualTokens, bytes32[] memory balances) = _getPoolTokens(poolId);
              InputHelpers.ensureInputLengthMatch(actualTokens.length, expectedTokens.length);
              _require(actualTokens.length > 0, Errors.POOL_NO_TOKENS);
              for (uint256 i = 0; i < actualTokens.length; ++i) {
                  _require(actualTokens[i] == expectedTokens[i], Errors.TOKENS_MISMATCH);
              }
              return balances;
          }
          /**
           * @dev Casts an array of uint256 to int256, setting the sign of the result according to the `positive` flag,
           * without checking whether the values fit in the signed 256 bit range.
           */
          function _unsafeCastToInt256(uint256[] memory values, bool positive)
              private
              pure
              returns (int256[] memory signedValues)
          {
              signedValues = new int256[](values.length);
              for (uint256 i = 0; i < values.length; i++) {
                  signedValues[i] = positive ? int256(values[i]) : -int256(values[i]);
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../../lib/openzeppelin/IERC20.sol";
      import "./IVault.sol";
      interface IPoolSwapStructs {
          // This is not really an interface - it just defines common structs used by other interfaces: IGeneralPool and
          // IMinimalSwapInfoPool.
          //
          // This data structure represents a request for a token swap, where `kind` indicates the swap type ('given in' or
          // 'given out') which indicates whether or not the amount sent by the pool is known.
          //
          // The pool receives `tokenIn` and sends `tokenOut`. `amount` is the number of `tokenIn` tokens the pool will take
          // in, or the number of `tokenOut` tokens the Pool will send out, depending on the given swap `kind`.
          //
          // All other fields are not strictly necessary for most swaps, but are provided to support advanced scenarios in
          // some Pools.
          //
          // `poolId` is the ID of the Pool involved in the swap - this is useful for Pool contracts that implement more than
          // one Pool.
          //
          // The meaning of `lastChangeBlock` depends on the Pool specialization:
          //  - Two Token or Minimal Swap Info: the last block in which either `tokenIn` or `tokenOut` changed its total
          //    balance.
          //  - General: the last block in which *any* of the Pool's registered tokens changed its total balance.
          //
          // `from` is the origin address for the funds the Pool receives, and `to` is the destination address
          // where the Pool sends the outgoing tokens.
          //
          // `userData` is extra data provided by the caller - typically a signature from a trusted party.
          struct SwapRequest {
              IVault.SwapKind kind;
              IERC20 tokenIn;
              IERC20 tokenOut;
              uint256 amount;
              // Misc data
              bytes32 poolId;
              uint256 lastChangeBlock;
              address from;
              address to;
              bytes userData;
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "./IBasePool.sol";
      /**
       * @dev IPools with the General specialization setting should implement this interface.
       *
       * This is called by the Vault when a user calls `IVault.swap` or `IVault.batchSwap` to swap with this Pool.
       * Returns the number of tokens the Pool will grant to the user in a 'given in' swap, or that the user will
       * grant to the pool in a 'given out' swap.
       *
       * This can often be implemented by a `view` function, since many pricing algorithms don't need to track state
       * changes in swaps. However, contracts implementing this in non-view functions should check that the caller is
       * indeed the Vault.
       */
      interface IGeneralPool is IBasePool {
          function onSwap(
              SwapRequest memory swapRequest,
              uint256[] memory balances,
              uint256 indexIn,
              uint256 indexOut
          ) external returns (uint256 amount);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "./IBasePool.sol";
      /**
       * @dev Pool contracts with the MinimalSwapInfo or TwoToken specialization settings should implement this interface.
       *
       * This is called by the Vault when a user calls `IVault.swap` or `IVault.batchSwap` to swap with this Pool.
       * Returns the number of tokens the Pool will grant to the user in a 'given in' swap, or that the user will grant
       * to the pool in a 'given out' swap.
       *
       * This can often be implemented by a `view` function, since many pricing algorithms don't need to track state
       * changes in swaps. However, contracts implementing this in non-view functions should check that the caller is
       * indeed the Vault.
       */
      interface IMinimalSwapInfoPool is IBasePool {
          function onSwap(
              SwapRequest memory swapRequest,
              uint256 currentBalanceTokenIn,
              uint256 currentBalanceTokenOut
          ) external returns (uint256 amount);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "../../lib/math/Math.sol";
      // This library is used to create a data structure that represents a token's balance for a Pool. 'cash' is how many
      // tokens the Pool has sitting inside of the Vault. 'managed' is how many tokens were withdrawn from the Vault by the
      // Pool's Asset Manager. 'total' is the sum of these two, and represents the Pool's total token balance, including
      // tokens that are *not* inside of the Vault.
      //
      // 'cash' is updated whenever tokens enter and exit the Vault, while 'managed' is only updated if the reason tokens are
      // moving is due to an Asset Manager action. This is reflected in the different methods available: 'increaseCash'
      // and 'decreaseCash' for swaps and add/remove liquidity events, and 'cashToManaged' and 'managedToCash' for events
      // transferring funds to and from the Asset Manager.
      //
      // The Vault disallows the Pool's 'cash' from becoming negative. In other words, it can never use any tokens that are
      // not inside the Vault.
      //
      // One of the goals of this library is to store the entire token balance in a single storage slot, which is why we use
      // 112 bit unsigned integers for 'cash' and 'managed'. For consistency, we also disallow any combination of 'cash' and
      // 'managed' that yields a 'total' that doesn't fit in 112 bits.
      //
      // The remaining 32 bits of the slot are used to store the most recent block when the total balance changed. This
      // can be used to implement price oracles that are resilient to 'sandwich' attacks.
      //
      // We could use a Solidity struct to pack these three values together in a single storage slot, but unfortunately
      // Solidity only allows for structs to live in either storage, calldata or memory. Because a memory struct still takes
      // up a slot in the stack (to store its memory location), and because the entire balance fits in a single stack slot
      // (two 112 bit values plus the 32 bit block), using memory is strictly less gas performant. Therefore, we do manual
      // packing and unpacking.
      //
      // Since we cannot define new types, we rely on bytes32 to represent these values instead, as it doesn't have any
      // associated arithmetic operations and therefore reduces the chance of misuse.
      library BalanceAllocation {
          using Math for uint256;
          // The 'cash' portion of the balance is stored in the least significant 112 bits of a 256 bit word, while the
          // 'managed' part uses the following 112 bits. The most significant 32 bits are used to store the block
          /**
           * @dev Returns the total amount of Pool tokens, including those that are not currently in the Vault ('managed').
           */
          function total(bytes32 balance) internal pure returns (uint256) {
              // Since 'cash' and 'managed' are 112 bit values, we don't need checked arithmetic. Additionally, `toBalance`
              // ensures that 'total' always fits in 112 bits.
              return cash(balance) + managed(balance);
          }
          /**
           * @dev Returns the amount of Pool tokens currently in the Vault.
           */
          function cash(bytes32 balance) internal pure returns (uint256) {
              uint256 mask = 2**(112) - 1;
              return uint256(balance) & mask;
          }
          /**
           * @dev Returns the amount of Pool tokens that are being managed by an Asset Manager.
           */
          function managed(bytes32 balance) internal pure returns (uint256) {
              uint256 mask = 2**(112) - 1;
              return uint256(balance >> 112) & mask;
          }
          /**
           * @dev Returns the last block when the total balance changed.
           */
          function lastChangeBlock(bytes32 balance) internal pure returns (uint256) {
              uint256 mask = 2**(32) - 1;
              return uint256(balance >> 224) & mask;
          }
          /**
           * @dev Returns the difference in 'managed' between two balances.
           */
          function managedDelta(bytes32 newBalance, bytes32 oldBalance) internal pure returns (int256) {
              // Because `managed` is a 112 bit value, we can safely perform unchecked arithmetic in 256 bits.
              return int256(managed(newBalance)) - int256(managed(oldBalance));
          }
          /**
           * @dev Returns the total balance for each entry in `balances`, as well as the latest block when the total
           * balance of *any* of them last changed.
           */
          function totalsAndLastChangeBlock(bytes32[] memory balances)
              internal
              pure
              returns (
                  uint256[] memory results,
                  uint256 lastChangeBlock_ // Avoid shadowing
              )
          {
              results = new uint256[](balances.length);
              lastChangeBlock_ = 0;
              for (uint256 i = 0; i < results.length; i++) {
                  bytes32 balance = balances[i];
                  results[i] = total(balance);
                  lastChangeBlock_ = Math.max(lastChangeBlock_, lastChangeBlock(balance));
              }
          }
          /**
           * @dev Returns true if `balance`'s 'total' balance is zero. Costs less gas than computing 'total' and comparing
           * with zero.
           */
          function isZero(bytes32 balance) internal pure returns (bool) {
              // We simply need to check the least significant 224 bytes of the word: the block does not affect this.
              uint256 mask = 2**(224) - 1;
              return (uint256(balance) & mask) == 0;
          }
          /**
           * @dev Returns true if `balance`'s 'total' balance is not zero. Costs less gas than computing 'total' and comparing
           * with zero.
           */
          function isNotZero(bytes32 balance) internal pure returns (bool) {
              return !isZero(balance);
          }
          /**
           * @dev Packs together `cash` and `managed` amounts with a block to create a balance value.
           *
           * For consistency, this also checks that the sum of `cash` and `managed` (`total`) fits in 112 bits.
           */
          function toBalance(
              uint256 _cash,
              uint256 _managed,
              uint256 _blockNumber
          ) internal pure returns (bytes32) {
              uint256 _total = _cash + _managed;
              // Since both 'cash' and 'managed' are positive integers, by checking that their sum ('total') fits in 112 bits
              // we are also indirectly checking that both 'cash' and 'managed' themselves fit in 112 bits.
              _require(_total >= _cash && _total < 2**112, Errors.BALANCE_TOTAL_OVERFLOW);
              // We assume the block fits in 32 bits - this is expected to hold for at least a few decades.
              return _pack(_cash, _managed, _blockNumber);
          }
          /**
           * @dev Increases a Pool's 'cash' (and therefore its 'total'). Called when Pool tokens are sent to the Vault (except
           * for Asset Manager deposits).
           *
           * Updates the last total balance change block, even if `amount` is zero.
           */
          function increaseCash(bytes32 balance, uint256 amount) internal view returns (bytes32) {
              uint256 newCash = cash(balance).add(amount);
              uint256 currentManaged = managed(balance);
              uint256 newLastChangeBlock = block.number;
              return toBalance(newCash, currentManaged, newLastChangeBlock);
          }
          /**
           * @dev Decreases a Pool's 'cash' (and therefore its 'total'). Called when Pool tokens are sent from the Vault
           * (except for Asset Manager withdrawals).
           *
           * Updates the last total balance change block, even if `amount` is zero.
           */
          function decreaseCash(bytes32 balance, uint256 amount) internal view returns (bytes32) {
              uint256 newCash = cash(balance).sub(amount);
              uint256 currentManaged = managed(balance);
              uint256 newLastChangeBlock = block.number;
              return toBalance(newCash, currentManaged, newLastChangeBlock);
          }
          /**
           * @dev Moves 'cash' into 'managed', leaving 'total' unchanged. Called when an Asset Manager withdraws Pool tokens
           * from the Vault.
           */
          function cashToManaged(bytes32 balance, uint256 amount) internal pure returns (bytes32) {
              uint256 newCash = cash(balance).sub(amount);
              uint256 newManaged = managed(balance).add(amount);
              uint256 currentLastChangeBlock = lastChangeBlock(balance);
              return toBalance(newCash, newManaged, currentLastChangeBlock);
          }
          /**
           * @dev Moves 'managed' into 'cash', leaving 'total' unchanged. Called when an Asset Manager deposits Pool tokens
           * into the Vault.
           */
          function managedToCash(bytes32 balance, uint256 amount) internal pure returns (bytes32) {
              uint256 newCash = cash(balance).add(amount);
              uint256 newManaged = managed(balance).sub(amount);
              uint256 currentLastChangeBlock = lastChangeBlock(balance);
              return toBalance(newCash, newManaged, currentLastChangeBlock);
          }
          /**
           * @dev Sets 'managed' balance to an arbitrary value, changing 'total'. Called when the Asset Manager reports
           * profits or losses. It's the Manager's responsibility to provide a meaningful value.
           *
           * Updates the last total balance change block, even if `newManaged` is equal to the current 'managed' value.
           */
          function setManaged(bytes32 balance, uint256 newManaged) internal view returns (bytes32) {
              uint256 currentCash = cash(balance);
              uint256 newLastChangeBlock = block.number;
              return toBalance(currentCash, newManaged, newLastChangeBlock);
          }
          // Alternative mode for Pools with the Two Token specialization setting
          // Instead of storing cash and external for each 'token in' a single storage slot, Two Token Pools store the cash
          // for both tokens in the same slot, and the managed for both in another one. This reduces the gas cost for swaps,
          // because the only slot that needs to be updated is the one with the cash. However, it also means that managing
          // balances is more cumbersome, as both tokens need to be read/written at the same time.
          //
          // The field with both cash balances packed is called sharedCash, and the one with external amounts is called
          // sharedManaged. These two are collectively called the 'shared' balance fields. In both of these, the portion
          // that corresponds to token A is stored in the least significant 112 bits of a 256 bit word, while token B's part
          // uses the next least significant 112 bits.
          //
          // Because only cash is written to during a swap, we store the last total balance change block with the
          // packed cash fields. Typically Pools have a distinct block per token: in the case of Two Token Pools they
          // are the same.
          /**
           * @dev Extracts the part of the balance that corresponds to token A. This function can be used to decode both
           * shared cash and managed balances.
           */
          function _decodeBalanceA(bytes32 sharedBalance) private pure returns (uint256) {
              uint256 mask = 2**(112) - 1;
              return uint256(sharedBalance) & mask;
          }
          /**
           * @dev Extracts the part of the balance that corresponds to token B. This function can be used to decode both
           * shared cash and managed balances.
           */
          function _decodeBalanceB(bytes32 sharedBalance) private pure returns (uint256) {
              uint256 mask = 2**(112) - 1;
              return uint256(sharedBalance >> 112) & mask;
          }
          // To decode the last balance change block, we can simply use the `blockNumber` function.
          /**
           * @dev Unpacks the shared token A and token B cash and managed balances into the balance for token A.
           */
          function fromSharedToBalanceA(bytes32 sharedCash, bytes32 sharedManaged) internal pure returns (bytes32) {
              // Note that we extract the block from the sharedCash field, which is the one that is updated by swaps.
              // Both token A and token B use the same block
              return toBalance(_decodeBalanceA(sharedCash), _decodeBalanceA(sharedManaged), lastChangeBlock(sharedCash));
          }
          /**
           * @dev Unpacks the shared token A and token B cash and managed balances into the balance for token B.
           */
          function fromSharedToBalanceB(bytes32 sharedCash, bytes32 sharedManaged) internal pure returns (bytes32) {
              // Note that we extract the block from the sharedCash field, which is the one that is updated by swaps.
              // Both token A and token B use the same block
              return toBalance(_decodeBalanceB(sharedCash), _decodeBalanceB(sharedManaged), lastChangeBlock(sharedCash));
          }
          /**
           * @dev Returns the sharedCash shared field, given the current balances for token A and token B.
           */
          function toSharedCash(bytes32 tokenABalance, bytes32 tokenBBalance) internal pure returns (bytes32) {
              // Both balances are assigned the same block  Since it is possible a single one of them has changed (for
              // example, in an Asset Manager update), we keep the latest (largest) one.
              uint32 newLastChangeBlock = uint32(Math.max(lastChangeBlock(tokenABalance), lastChangeBlock(tokenBBalance)));
              return _pack(cash(tokenABalance), cash(tokenBBalance), newLastChangeBlock);
          }
          /**
           * @dev Returns the sharedManaged shared field, given the current balances for token A and token B.
           */
          function toSharedManaged(bytes32 tokenABalance, bytes32 tokenBBalance) internal pure returns (bytes32) {
              // We don't bother storing a last change block, as it is read from the shared cash field.
              return _pack(managed(tokenABalance), managed(tokenBBalance), 0);
          }
          // Shared functions
          /**
           * @dev Packs together two uint112 and one uint32 into a bytes32
           */
          function _pack(
              uint256 _leastSignificant,
              uint256 _midSignificant,
              uint256 _mostSignificant
          ) private pure returns (bytes32) {
              return bytes32((_mostSignificant << 224) + (_midSignificant << 112) + _leastSignificant);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../lib/helpers/BalancerErrors.sol";
      import "../lib/openzeppelin/ReentrancyGuard.sol";
      import "./AssetManagers.sol";
      import "./PoolRegistry.sol";
      import "./balances/BalanceAllocation.sol";
      abstract contract PoolTokens is ReentrancyGuard, PoolRegistry, AssetManagers {
          using BalanceAllocation for bytes32;
          using BalanceAllocation for bytes32[];
          function registerTokens(
              bytes32 poolId,
              IERC20[] memory tokens,
              address[] memory assetManagers
          ) external override nonReentrant whenNotPaused onlyPool(poolId) {
              InputHelpers.ensureInputLengthMatch(tokens.length, assetManagers.length);
              // Validates token addresses and assigns Asset Managers
              for (uint256 i = 0; i < tokens.length; ++i) {
                  IERC20 token = tokens[i];
                  _require(token != IERC20(0), Errors.INVALID_TOKEN);
                  _poolAssetManagers[poolId][token] = assetManagers[i];
              }
              PoolSpecialization specialization = _getPoolSpecialization(poolId);
              if (specialization == PoolSpecialization.TWO_TOKEN) {
                  _require(tokens.length == 2, Errors.TOKENS_LENGTH_MUST_BE_2);
                  _registerTwoTokenPoolTokens(poolId, tokens[0], tokens[1]);
              } else if (specialization == PoolSpecialization.MINIMAL_SWAP_INFO) {
                  _registerMinimalSwapInfoPoolTokens(poolId, tokens);
              } else {
                  // PoolSpecialization.GENERAL
                  _registerGeneralPoolTokens(poolId, tokens);
              }
              emit TokensRegistered(poolId, tokens, assetManagers);
          }
          function deregisterTokens(bytes32 poolId, IERC20[] memory tokens)
              external
              override
              nonReentrant
              whenNotPaused
              onlyPool(poolId)
          {
              PoolSpecialization specialization = _getPoolSpecialization(poolId);
              if (specialization == PoolSpecialization.TWO_TOKEN) {
                  _require(tokens.length == 2, Errors.TOKENS_LENGTH_MUST_BE_2);
                  _deregisterTwoTokenPoolTokens(poolId, tokens[0], tokens[1]);
              } else if (specialization == PoolSpecialization.MINIMAL_SWAP_INFO) {
                  _deregisterMinimalSwapInfoPoolTokens(poolId, tokens);
              } else {
                  // PoolSpecialization.GENERAL
                  _deregisterGeneralPoolTokens(poolId, tokens);
              }
              // The deregister calls above ensure the total token balance is zero. Therefore it is now safe to remove any
              // associated Asset Managers, since they hold no Pool balance.
              for (uint256 i = 0; i < tokens.length; ++i) {
                  delete _poolAssetManagers[poolId][tokens[i]];
              }
              emit TokensDeregistered(poolId, tokens);
          }
          function getPoolTokens(bytes32 poolId)
              external
              view
              override
              withRegisteredPool(poolId)
              returns (
                  IERC20[] memory tokens,
                  uint256[] memory balances,
                  uint256 lastChangeBlock
              )
          {
              bytes32[] memory rawBalances;
              (tokens, rawBalances) = _getPoolTokens(poolId);
              (balances, lastChangeBlock) = rawBalances.totalsAndLastChangeBlock();
          }
          function getPoolTokenInfo(bytes32 poolId, IERC20 token)
              external
              view
              override
              withRegisteredPool(poolId)
              returns (
                  uint256 cash,
                  uint256 managed,
                  uint256 lastChangeBlock,
                  address assetManager
              )
          {
              bytes32 balance;
              PoolSpecialization specialization = _getPoolSpecialization(poolId);
              if (specialization == PoolSpecialization.TWO_TOKEN) {
                  balance = _getTwoTokenPoolBalance(poolId, token);
              } else if (specialization == PoolSpecialization.MINIMAL_SWAP_INFO) {
                  balance = _getMinimalSwapInfoPoolBalance(poolId, token);
              } else {
                  // PoolSpecialization.GENERAL
                  balance = _getGeneralPoolBalance(poolId, token);
              }
              cash = balance.cash();
              managed = balance.managed();
              lastChangeBlock = balance.lastChangeBlock();
              assetManager = _poolAssetManagers[poolId][token];
          }
          /**
           * @dev Returns all of `poolId`'s registered tokens, along with their raw balances.
           */
          function _getPoolTokens(bytes32 poolId) internal view returns (IERC20[] memory tokens, bytes32[] memory balances) {
              PoolSpecialization specialization = _getPoolSpecialization(poolId);
              if (specialization == PoolSpecialization.TWO_TOKEN) {
                  return _getTwoTokenPoolTokens(poolId);
              } else if (specialization == PoolSpecialization.MINIMAL_SWAP_INFO) {
                  return _getMinimalSwapInfoPoolTokens(poolId);
              } else {
                  // PoolSpecialization.GENERAL
                  return _getGeneralPoolTokens(poolId);
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../lib/helpers/BalancerErrors.sol";
      import "../lib/math/Math.sol";
      import "../lib/openzeppelin/IERC20.sol";
      import "../lib/openzeppelin/ReentrancyGuard.sol";
      import "../lib/openzeppelin/SafeCast.sol";
      import "../lib/openzeppelin/SafeERC20.sol";
      import "./AssetTransfersHandler.sol";
      import "./VaultAuthorization.sol";
      /**
       * Implement User Balance interactions, which combine Internal Balance and using the Vault's ERC20 allowance.
       *
       * Users can deposit tokens into the Vault, where they are allocated to their Internal Balance, and later
       * transferred or withdrawn. It can also be used as a source of tokens when joining Pools, as a destination
       * when exiting them, and as either when performing swaps. This usage of Internal Balance results in greatly reduced
       * gas costs when compared to relying on plain ERC20 transfers, leading to large savings for frequent users.
       *
       * Internal Balance management features batching, which means a single contract call can be used to perform multiple
       * operations of different kinds, with different senders and recipients, at once.
       */
      abstract contract UserBalance is ReentrancyGuard, AssetTransfersHandler, VaultAuthorization {
          using Math for uint256;
          using SafeCast for uint256;
          using SafeERC20 for IERC20;
          // Internal Balance for each token, for each account.
          mapping(address => mapping(IERC20 => uint256)) private _internalTokenBalance;
          function getInternalBalance(address user, IERC20[] memory tokens)
              external
              view
              override
              returns (uint256[] memory balances)
          {
              balances = new uint256[](tokens.length);
              for (uint256 i = 0; i < tokens.length; i++) {
                  balances[i] = _getInternalBalance(user, tokens[i]);
              }
          }
          function manageUserBalance(UserBalanceOp[] memory ops) external payable override nonReentrant {
              // We need to track how much of the received ETH was used and wrapped into WETH to return any excess.
              uint256 ethWrapped = 0;
              // Cache for these checks so we only perform them once (if at all).
              bool checkedCallerIsRelayer = false;
              bool checkedNotPaused = false;
              for (uint256 i = 0; i < ops.length; i++) {
                  UserBalanceOpKind kind;
                  IAsset asset;
                  uint256 amount;
                  address sender;
                  address payable recipient;
                  // This destructuring by calling `_validateUserBalanceOp` seems odd, but results in reduced bytecode size.
                  (kind, asset, amount, sender, recipient, checkedCallerIsRelayer) = _validateUserBalanceOp(
                      ops[i],
                      checkedCallerIsRelayer
                  );
                  if (kind == UserBalanceOpKind.WITHDRAW_INTERNAL) {
                      // Internal Balance withdrawals can always be performed by an authorized account.
                      _withdrawFromInternalBalance(asset, sender, recipient, amount);
                  } else {
                      // All other operations are blocked if the contract is paused.
                      // We cache the result of the pause check and skip it for other operations in this same transaction
                      // (if any).
                      if (!checkedNotPaused) {
                          _ensureNotPaused();
                          checkedNotPaused = true;
                      }
                      if (kind == UserBalanceOpKind.DEPOSIT_INTERNAL) {
                          _depositToInternalBalance(asset, sender, recipient, amount);
                          // Keep track of all ETH wrapped into WETH as part of a deposit.
                          if (_isETH(asset)) {
                              ethWrapped = ethWrapped.add(amount);
                          }
                      } else {
                          // Transfers don't support ETH.
                          _require(!_isETH(asset), Errors.CANNOT_USE_ETH_SENTINEL);
                          IERC20 token = _asIERC20(asset);
                          if (kind == UserBalanceOpKind.TRANSFER_INTERNAL) {
                              _transferInternalBalance(token, sender, recipient, amount);
                          } else {
                              // TRANSFER_EXTERNAL
                              _transferToExternalBalance(token, sender, recipient, amount);
                          }
                      }
                  }
              }
              // Handle any remaining ETH.
              _handleRemainingEth(ethWrapped);
          }
          function _depositToInternalBalance(
              IAsset asset,
              address sender,
              address recipient,
              uint256 amount
          ) private {
              _increaseInternalBalance(recipient, _translateToIERC20(asset), amount);
              _receiveAsset(asset, amount, sender, false);
          }
          function _withdrawFromInternalBalance(
              IAsset asset,
              address sender,
              address payable recipient,
              uint256 amount
          ) private {
              // A partial decrease of Internal Balance is disallowed: `sender` must have the full `amount`.
              _decreaseInternalBalance(sender, _translateToIERC20(asset), amount, false);
              _sendAsset(asset, amount, recipient, false);
          }
          function _transferInternalBalance(
              IERC20 token,
              address sender,
              address recipient,
              uint256 amount
          ) private {
              // A partial decrease of Internal Balance is disallowed: `sender` must have the full `amount`.
              _decreaseInternalBalance(sender, token, amount, false);
              _increaseInternalBalance(recipient, token, amount);
          }
          function _transferToExternalBalance(
              IERC20 token,
              address sender,
              address recipient,
              uint256 amount
          ) private {
              if (amount > 0) {
                  token.safeTransferFrom(sender, recipient, amount);
                  emit ExternalBalanceTransfer(token, sender, recipient, amount);
              }
          }
          /**
           * @dev Increases `account`'s Internal Balance for `token` by `amount`.
           */
          function _increaseInternalBalance(
              address account,
              IERC20 token,
              uint256 amount
          ) internal override {
              uint256 currentBalance = _getInternalBalance(account, token);
              uint256 newBalance = currentBalance.add(amount);
              _setInternalBalance(account, token, newBalance, amount.toInt256());
          }
          /**
           * @dev Decreases `account`'s Internal Balance for `token` by `amount`. If `allowPartial` is true, this function
           * doesn't revert if `account` doesn't have enough balance, and sets it to zero and returns the deducted amount
           * instead.
           */
          function _decreaseInternalBalance(
              address account,
              IERC20 token,
              uint256 amount,
              bool allowPartial
          ) internal override returns (uint256 deducted) {
              uint256 currentBalance = _getInternalBalance(account, token);
              _require(allowPartial || (currentBalance >= amount), Errors.INSUFFICIENT_INTERNAL_BALANCE);
              deducted = Math.min(currentBalance, amount);
              // By construction, `deducted` is lower or equal to `currentBalance`, so we don't need to use checked
              // arithmetic.
              uint256 newBalance = currentBalance - deducted;
              _setInternalBalance(account, token, newBalance, -(deducted.toInt256()));
          }
          /**
           * @dev Sets `account`'s Internal Balance for `token` to `newBalance`.
           *
           * Emits an `InternalBalanceChanged` event. This event includes `delta`, which is the amount the balance increased
           * (if positive) or decreased (if negative). To avoid reading the current balance in order to compute the delta,
           * this function relies on the caller providing it directly.
           */
          function _setInternalBalance(
              address account,
              IERC20 token,
              uint256 newBalance,
              int256 delta
          ) private {
              _internalTokenBalance[account][token] = newBalance;
              emit InternalBalanceChanged(account, token, delta);
          }
          /**
           * @dev Returns `account`'s Internal Balance for `token`.
           */
          function _getInternalBalance(address account, IERC20 token) internal view returns (uint256) {
              return _internalTokenBalance[account][token];
          }
          /**
           * @dev Destructures a User Balance operation, validating that the contract caller is allowed to perform it.
           */
          function _validateUserBalanceOp(UserBalanceOp memory op, bool checkedCallerIsRelayer)
              private
              view
              returns (
                  UserBalanceOpKind,
                  IAsset,
                  uint256,
                  address,
                  address payable,
                  bool
              )
          {
              // The only argument we need to validate is `sender`, which can only be either the contract caller, or a
              // relayer approved by `sender`.
              address sender = op.sender;
              if (sender != msg.sender) {
                  // We need to check both that the contract caller is a relayer, and that `sender` approved them.
                  // Because the relayer check is global (i.e. independent of `sender`), we cache that result and skip it for
                  // other operations in this same transaction (if any).
                  if (!checkedCallerIsRelayer) {
                      _authenticateCaller();
                      checkedCallerIsRelayer = true;
                  }
                  _require(_hasApprovedRelayer(sender, msg.sender), Errors.USER_DOESNT_ALLOW_RELAYER);
              }
              return (op.kind, op.asset, op.amount, sender, op.recipient, checkedCallerIsRelayer);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "./IVault.sol";
      import "./IPoolSwapStructs.sol";
      /**
       * @dev Interface for adding and removing liquidity that all Pool contracts should implement. Note that this is not
       * the complete Pool contract interface, as it is missing the swap hooks. Pool contracts should also inherit from
       * either IGeneralPool or IMinimalSwapInfoPool
       */
      interface IBasePool is IPoolSwapStructs {
          /**
           * @dev Called by the Vault when a user calls `IVault.joinPool` to add liquidity to this Pool. Returns how many of
           * each registered token the user should provide, as well as the amount of protocol fees the Pool owes to the Vault.
           * The Vault will then take tokens from `sender` and add them to the Pool's balances, as well as collect
           * the reported amount in protocol fees, which the pool should calculate based on `protocolSwapFeePercentage`.
           *
           * Protocol fees are reported and charged on join events so that the Pool is free of debt whenever new users join.
           *
           * `sender` is the account performing the join (from which tokens will be withdrawn), and `recipient` is the account
           * designated to receive any benefits (typically pool shares). `currentBalances` contains the total balances
           * for each token the Pool registered in the Vault, in the same order that `IVault.getPoolTokens` would return.
           *
           * `lastChangeBlock` is the last block in which *any* of the Pool's registered tokens last changed its total
           * balance.
           *
           * `userData` contains any pool-specific instructions needed to perform the calculations, such as the type of
           * join (e.g., proportional given an amount of pool shares, single-asset, multi-asset, etc.)
           *
           * Contracts implementing this function should check that the caller is indeed the Vault before performing any
           * state-changing operations, such as minting pool shares.
           */
          function onJoinPool(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory balances,
              uint256 lastChangeBlock,
              uint256 protocolSwapFeePercentage,
              bytes memory userData
          ) external returns (uint256[] memory amountsIn, uint256[] memory dueProtocolFeeAmounts);
          /**
           * @dev Called by the Vault when a user calls `IVault.exitPool` to remove liquidity from this Pool. Returns how many
           * tokens the Vault should deduct from the Pool's balances, as well as the amount of protocol fees the Pool owes
           * to the Vault. The Vault will then take tokens from the Pool's balances and send them to `recipient`,
           * as well as collect the reported amount in protocol fees, which the Pool should calculate based on
           * `protocolSwapFeePercentage`.
           *
           * Protocol fees are charged on exit events to guarantee that users exiting the Pool have paid their share.
           *
           * `sender` is the account performing the exit (typically the pool shareholder), and `recipient` is the account
           * to which the Vault will send the proceeds. `currentBalances` contains the total token balances for each token
           * the Pool registered in the Vault, in the same order that `IVault.getPoolTokens` would return.
           *
           * `lastChangeBlock` is the last block in which *any* of the Pool's registered tokens last changed its total
           * balance.
           *
           * `userData` contains any pool-specific instructions needed to perform the calculations, such as the type of
           * exit (e.g., proportional given an amount of pool shares, single-asset, multi-asset, etc.)
           *
           * Contracts implementing this function should check that the caller is indeed the Vault before performing any
           * state-changing operations, such as burning pool shares.
           */
          function onExitPool(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory balances,
              uint256 lastChangeBlock,
              uint256 protocolSwapFeePercentage,
              bytes memory userData
          ) external returns (uint256[] memory amountsOut, uint256[] memory dueProtocolFeeAmounts);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../lib/math/Math.sol";
      import "../lib/helpers/BalancerErrors.sol";
      import "../lib/helpers/InputHelpers.sol";
      import "../lib/openzeppelin/IERC20.sol";
      import "../lib/openzeppelin/SafeERC20.sol";
      import "../lib/openzeppelin/ReentrancyGuard.sol";
      import "./UserBalance.sol";
      import "./balances/BalanceAllocation.sol";
      import "./balances/GeneralPoolsBalance.sol";
      import "./balances/MinimalSwapInfoPoolsBalance.sol";
      import "./balances/TwoTokenPoolsBalance.sol";
      abstract contract AssetManagers is
          ReentrancyGuard,
          GeneralPoolsBalance,
          MinimalSwapInfoPoolsBalance,
          TwoTokenPoolsBalance
      {
          using Math for uint256;
          using SafeERC20 for IERC20;
          // Stores the Asset Manager for each token of each Pool.
          mapping(bytes32 => mapping(IERC20 => address)) internal _poolAssetManagers;
          function managePoolBalance(PoolBalanceOp[] memory ops) external override nonReentrant whenNotPaused {
              // This variable could be declared inside the loop, but that causes the compiler to allocate memory on each
              // loop iteration, increasing gas costs.
              PoolBalanceOp memory op;
              for (uint256 i = 0; i < ops.length; ++i) {
                  // By indexing the array only once, we don't spend extra gas in the same bounds check.
                  op = ops[i];
                  bytes32 poolId = op.poolId;
                  _ensureRegisteredPool(poolId);
                  IERC20 token = op.token;
                  _require(_isTokenRegistered(poolId, token), Errors.TOKEN_NOT_REGISTERED);
                  _require(_poolAssetManagers[poolId][token] == msg.sender, Errors.SENDER_NOT_ASSET_MANAGER);
                  PoolBalanceOpKind kind = op.kind;
                  uint256 amount = op.amount;
                  (int256 cashDelta, int256 managedDelta) = _performPoolManagementOperation(kind, poolId, token, amount);
                  emit PoolBalanceManaged(poolId, msg.sender, token, cashDelta, managedDelta);
              }
          }
          /**
           * @dev Performs the `kind` Asset Manager operation on a Pool.
           *
           * Withdrawals will transfer `amount` tokens to the caller, deposits will transfer `amount` tokens from the caller,
           * and updates will set the managed balance to `amount`.
           *
           * Returns a tuple with the 'cash' and 'managed' balance deltas as a result of this call.
           */
          function _performPoolManagementOperation(
              PoolBalanceOpKind kind,
              bytes32 poolId,
              IERC20 token,
              uint256 amount
          ) private returns (int256, int256) {
              PoolSpecialization specialization = _getPoolSpecialization(poolId);
              if (kind == PoolBalanceOpKind.WITHDRAW) {
                  return _withdrawPoolBalance(poolId, specialization, token, amount);
              } else if (kind == PoolBalanceOpKind.DEPOSIT) {
                  return _depositPoolBalance(poolId, specialization, token, amount);
              } else {
                  // PoolBalanceOpKind.UPDATE
                  return _updateManagedBalance(poolId, specialization, token, amount);
              }
          }
          /**
           * @dev Moves `amount` tokens from a Pool's 'cash' to 'managed' balance, and transfers them to the caller.
           *
           * Returns the 'cash' and 'managed' balance deltas as a result of this call, which will be complementary.
           */
          function _withdrawPoolBalance(
              bytes32 poolId,
              PoolSpecialization specialization,
              IERC20 token,
              uint256 amount
          ) private returns (int256 cashDelta, int256 managedDelta) {
              if (specialization == PoolSpecialization.TWO_TOKEN) {
                  _twoTokenPoolCashToManaged(poolId, token, amount);
              } else if (specialization == PoolSpecialization.MINIMAL_SWAP_INFO) {
                  _minimalSwapInfoPoolCashToManaged(poolId, token, amount);
              } else {
                  // PoolSpecialization.GENERAL
                  _generalPoolCashToManaged(poolId, token, amount);
              }
              if (amount > 0) {
                  token.safeTransfer(msg.sender, amount);
              }
              // Since 'cash' and 'managed' are stored as uint112, `amount` is guaranteed to also fit in 112 bits. It will
              // therefore always fit in a 256 bit integer.
              cashDelta = int256(-amount);
              managedDelta = int256(amount);
          }
          /**
           * @dev Moves `amount` tokens from a Pool's 'managed' to 'cash' balance, and transfers them from the caller.
           *
           * Returns the 'cash' and 'managed' balance deltas as a result of this call, which will be complementary.
           */
          function _depositPoolBalance(
              bytes32 poolId,
              PoolSpecialization specialization,
              IERC20 token,
              uint256 amount
          ) private returns (int256 cashDelta, int256 managedDelta) {
              if (specialization == PoolSpecialization.TWO_TOKEN) {
                  _twoTokenPoolManagedToCash(poolId, token, amount);
              } else if (specialization == PoolSpecialization.MINIMAL_SWAP_INFO) {
                  _minimalSwapInfoPoolManagedToCash(poolId, token, amount);
              } else {
                  // PoolSpecialization.GENERAL
                  _generalPoolManagedToCash(poolId, token, amount);
              }
              if (amount > 0) {
                  token.safeTransferFrom(msg.sender, address(this), amount);
              }
              // Since 'cash' and 'managed' are stored as uint112, `amount` is guaranteed to also fit in 112 bits. It will
              // therefore always fit in a 256 bit integer.
              cashDelta = int256(amount);
              managedDelta = int256(-amount);
          }
          /**
           * @dev Sets a Pool's 'managed' balance to `amount`.
           *
           * Returns the 'cash' and 'managed' balance deltas as a result of this call (the 'cash' delta will always be zero).
           */
          function _updateManagedBalance(
              bytes32 poolId,
              PoolSpecialization specialization,
              IERC20 token,
              uint256 amount
          ) private returns (int256 cashDelta, int256 managedDelta) {
              if (specialization == PoolSpecialization.TWO_TOKEN) {
                  managedDelta = _setTwoTokenPoolManagedBalance(poolId, token, amount);
              } else if (specialization == PoolSpecialization.MINIMAL_SWAP_INFO) {
                  managedDelta = _setMinimalSwapInfoPoolManagedBalance(poolId, token, amount);
              } else {
                  // PoolSpecialization.GENERAL
                  managedDelta = _setGeneralPoolManagedBalance(poolId, token, amount);
              }
              cashDelta = 0;
          }
          /**
           * @dev Returns true if `token` is registered for `poolId`.
           */
          function _isTokenRegistered(bytes32 poolId, IERC20 token) private view returns (bool) {
              PoolSpecialization specialization = _getPoolSpecialization(poolId);
              if (specialization == PoolSpecialization.TWO_TOKEN) {
                  return _isTwoTokenPoolTokenRegistered(poolId, token);
              } else if (specialization == PoolSpecialization.MINIMAL_SWAP_INFO) {
                  return _isMinimalSwapInfoPoolTokenRegistered(poolId, token);
              } else {
                  // PoolSpecialization.GENERAL
                  return _isGeneralPoolTokenRegistered(poolId, token);
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../lib/helpers/BalancerErrors.sol";
      import "../lib/openzeppelin/ReentrancyGuard.sol";
      import "./VaultAuthorization.sol";
      /**
       * @dev Maintains the Pool ID data structure, implements Pool ID creation and registration, and defines useful modifiers
       * and helper functions for ensuring correct behavior when working with Pools.
       */
      abstract contract PoolRegistry is ReentrancyGuard, VaultAuthorization {
          // Each pool is represented by their unique Pool ID. We use `bytes32` for them, for lack of a way to define new
          // types.
          mapping(bytes32 => bool) private _isPoolRegistered;
          // We keep an increasing nonce to make Pool IDs unique. It is interpreted as a `uint80`, but storing it as a
          // `uint256` results in reduced bytecode on reads and writes due to the lack of masking.
          uint256 private _nextPoolNonce;
          /**
           * @dev Reverts unless `poolId` corresponds to a registered Pool.
           */
          modifier withRegisteredPool(bytes32 poolId) {
              _ensureRegisteredPool(poolId);
              _;
          }
          /**
           * @dev Reverts unless `poolId` corresponds to a registered Pool, and the caller is the Pool's contract.
           */
          modifier onlyPool(bytes32 poolId) {
              _ensurePoolIsSender(poolId);
              _;
          }
          /**
           * @dev Reverts unless `poolId` corresponds to a registered Pool.
           */
          function _ensureRegisteredPool(bytes32 poolId) internal view {
              _require(_isPoolRegistered[poolId], Errors.INVALID_POOL_ID);
          }
          /**
           * @dev Reverts unless `poolId` corresponds to a registered Pool, and the caller is the Pool's contract.
           */
          function _ensurePoolIsSender(bytes32 poolId) private view {
              _ensureRegisteredPool(poolId);
              _require(msg.sender == _getPoolAddress(poolId), Errors.CALLER_NOT_POOL);
          }
          function registerPool(PoolSpecialization specialization)
              external
              override
              nonReentrant
              whenNotPaused
              returns (bytes32)
          {
              // Each Pool is assigned a unique ID based on an incrementing nonce. This assumes there will never be more than
              // 2**80 Pools, and the nonce will not overflow.
              bytes32 poolId = _toPoolId(msg.sender, specialization, uint80(_nextPoolNonce));
              _require(!_isPoolRegistered[poolId], Errors.INVALID_POOL_ID); // Should never happen as Pool IDs are unique.
              _isPoolRegistered[poolId] = true;
              _nextPoolNonce += 1;
              // Note that msg.sender is the pool's contract
              emit PoolRegistered(poolId, msg.sender, specialization);
              return poolId;
          }
          function getPool(bytes32 poolId)
              external
              view
              override
              withRegisteredPool(poolId)
              returns (address, PoolSpecialization)
          {
              return (_getPoolAddress(poolId), _getPoolSpecialization(poolId));
          }
          /**
           * @dev Creates a Pool ID.
           *
           * These are deterministically created by packing the Pool's contract address and its specialization setting into
           * the ID. This saves gas by making this data easily retrievable from a Pool ID with no storage accesses.
           *
           * Since a single contract can register multiple Pools, a unique nonce must be provided to ensure Pool IDs are
           * unique.
           *
           * Pool IDs have the following layout:
           * | 20 bytes pool contract address | 2 bytes specialization setting | 10 bytes nonce |
           * MSB                                                                              LSB
           *
           * 2 bytes for the specialization setting is a bit overkill: there only three of them, which means two bits would
           * suffice. However, there's nothing else of interest to store in this extra space.
           */
          function _toPoolId(
              address pool,
              PoolSpecialization specialization,
              uint80 nonce
          ) internal pure returns (bytes32) {
              bytes32 serialized;
              serialized |= bytes32(uint256(nonce));
              serialized |= bytes32(uint256(specialization)) << (10 * 8);
              serialized |= bytes32(uint256(pool)) << (12 * 8);
              return serialized;
          }
          /**
           * @dev Returns the address of a Pool's contract.
           *
           * Due to how Pool IDs are created, this is done with no storage accesses and costs little gas.
           */
          function _getPoolAddress(bytes32 poolId) internal pure returns (address) {
              // 12 byte logical shift left to remove the nonce and specialization setting. We don't need to mask,
              // since the logical shift already sets the upper bits to zero.
              return address(uint256(poolId) >> (12 * 8));
          }
          /**
           * @dev Returns the specialization setting of a Pool.
           *
           * Due to how Pool IDs are created, this is done with no storage accesses and costs little gas.
           */
          function _getPoolSpecialization(bytes32 poolId) internal pure returns (PoolSpecialization specialization) {
              // 10 byte logical shift left to remove the nonce, followed by a 2 byte mask to remove the address.
              uint256 value = uint256(poolId >> (10 * 8)) & (2**(2 * 8) - 1);
              // Casting a value into an enum results in a runtime check that reverts unless the value is within the enum's
              // range. Passing an invalid Pool ID to this function would then result in an obscure revert with no reason
              // string: we instead perform the check ourselves to help in error diagnosis.
              // There are three Pool specialization settings: general, minimal swap info and two tokens, which correspond to
              // values 0, 1 and 2.
              _require(value < 3, Errors.INVALID_POOL_ID);
              // Because we have checked that `value` is within the enum range, we can use assembly to skip the runtime check.
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  specialization := value
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "../../lib/helpers/BalancerErrors.sol";
      import "../../lib/openzeppelin/EnumerableMap.sol";
      import "../../lib/openzeppelin/IERC20.sol";
      import "./BalanceAllocation.sol";
      abstract contract GeneralPoolsBalance {
          using BalanceAllocation for bytes32;
          using EnumerableMap for EnumerableMap.IERC20ToBytes32Map;
          // Data for Pools with the General specialization setting
          //
          // These Pools use the IGeneralPool interface, which means the Vault must query the balance for *all* of their
          // tokens in every swap. If we kept a mapping of token to balance plus a set (array) of tokens, it'd be very gas
          // intensive to read all token addresses just to then do a lookup on the balance mapping.
          //
          // Instead, we use our customized EnumerableMap, which lets us read the N balances in N+1 storage accesses (one for
          // each token in the Pool), access the index of any 'token in' a single read (required for the IGeneralPool call),
          // and update an entry's value given its index.
          // Map of token -> balance pairs for each Pool with this specialization. Many functions rely on storage pointers to
          // a Pool's EnumerableMap to save gas when computing storage slots.
          mapping(bytes32 => EnumerableMap.IERC20ToBytes32Map) internal _generalPoolsBalances;
          /**
           * @dev Registers a list of tokens in a General Pool.
           *
           * This function assumes `poolId` exists and corresponds to the General specialization setting.
           *
           * Requirements:
           *
           * - `tokens` must not be registered in the Pool
           * - `tokens` must not contain duplicates
           */
          function _registerGeneralPoolTokens(bytes32 poolId, IERC20[] memory tokens) internal {
              EnumerableMap.IERC20ToBytes32Map storage poolBalances = _generalPoolsBalances[poolId];
              for (uint256 i = 0; i < tokens.length; ++i) {
                  // EnumerableMaps require an explicit initial value when creating a key-value pair: we use zero, the same
                  // value that is found in uninitialized storage, which corresponds to an empty balance.
                  bool added = poolBalances.set(tokens[i], 0);
                  _require(added, Errors.TOKEN_ALREADY_REGISTERED);
              }
          }
          /**
           * @dev Deregisters a list of tokens in a General Pool.
           *
           * This function assumes `poolId` exists and corresponds to the General specialization setting.
           *
           * Requirements:
           *
           * - `tokens` must be registered in the Pool
           * - `tokens` must have zero balance in the Vault
           * - `tokens` must not contain duplicates
           */
          function _deregisterGeneralPoolTokens(bytes32 poolId, IERC20[] memory tokens) internal {
              EnumerableMap.IERC20ToBytes32Map storage poolBalances = _generalPoolsBalances[poolId];
              for (uint256 i = 0; i < tokens.length; ++i) {
                  IERC20 token = tokens[i];
                  bytes32 currentBalance = _getGeneralPoolBalance(poolBalances, token);
                  _require(currentBalance.isZero(), Errors.NONZERO_TOKEN_BALANCE);
                  // We don't need to check remove's return value, since _getGeneralPoolBalance already checks that the token
                  // was registered.
                  poolBalances.remove(token);
              }
          }
          /**
           * @dev Sets the balances of a General Pool's tokens to `balances`.
           *
           * WARNING: this assumes `balances` has the same length and order as the Pool's tokens.
           */
          function _setGeneralPoolBalances(bytes32 poolId, bytes32[] memory balances) internal {
              EnumerableMap.IERC20ToBytes32Map storage poolBalances = _generalPoolsBalances[poolId];
              for (uint256 i = 0; i < balances.length; ++i) {
                  // Since we assume all balances are properly ordered, we can simply use `unchecked_setAt` to avoid one less
                  // storage read per token.
                  poolBalances.unchecked_setAt(i, balances[i]);
              }
          }
          /**
           * @dev Transforms `amount` of `token`'s balance in a General Pool from cash into managed.
           *
           * This function assumes `poolId` exists, corresponds to the General specialization setting, and that `token` is
           * registered for that Pool.
           */
          function _generalPoolCashToManaged(
              bytes32 poolId,
              IERC20 token,
              uint256 amount
          ) internal {
              _updateGeneralPoolBalance(poolId, token, BalanceAllocation.cashToManaged, amount);
          }
          /**
           * @dev Transforms `amount` of `token`'s balance in a General Pool from managed into cash.
           *
           * This function assumes `poolId` exists, corresponds to the General specialization setting, and that `token` is
           * registered for that Pool.
           */
          function _generalPoolManagedToCash(
              bytes32 poolId,
              IERC20 token,
              uint256 amount
          ) internal {
              _updateGeneralPoolBalance(poolId, token, BalanceAllocation.managedToCash, amount);
          }
          /**
           * @dev Sets `token`'s managed balance in a General Pool to `amount`.
           *
           * This function assumes `poolId` exists, corresponds to the General specialization setting, and that `token` is
           * registered for that Pool.
           *
           * Returns the managed balance delta as a result of this call.
           */
          function _setGeneralPoolManagedBalance(
              bytes32 poolId,
              IERC20 token,
              uint256 amount
          ) internal returns (int256) {
              return _updateGeneralPoolBalance(poolId, token, BalanceAllocation.setManaged, amount);
          }
          /**
           * @dev Sets `token`'s balance in a General Pool to the result of the `mutation` function when called with the
           * current balance and `amount`.
           *
           * This function assumes `poolId` exists, corresponds to the General specialization setting, and that `token` is
           * registered for that Pool.
           *
           * Returns the managed balance delta as a result of this call.
           */
          function _updateGeneralPoolBalance(
              bytes32 poolId,
              IERC20 token,
              function(bytes32, uint256) returns (bytes32) mutation,
              uint256 amount
          ) private returns (int256) {
              EnumerableMap.IERC20ToBytes32Map storage poolBalances = _generalPoolsBalances[poolId];
              bytes32 currentBalance = _getGeneralPoolBalance(poolBalances, token);
              bytes32 newBalance = mutation(currentBalance, amount);
              poolBalances.set(token, newBalance);
              return newBalance.managedDelta(currentBalance);
          }
          /**
           * @dev Returns an array with all the tokens and balances in a General Pool. The order may change when tokens are
           * registered or deregistered.
           *
           * This function assumes `poolId` exists and corresponds to the General specialization setting.
           */
          function _getGeneralPoolTokens(bytes32 poolId)
              internal
              view
              returns (IERC20[] memory tokens, bytes32[] memory balances)
          {
              EnumerableMap.IERC20ToBytes32Map storage poolBalances = _generalPoolsBalances[poolId];
              tokens = new IERC20[](poolBalances.length());
              balances = new bytes32[](tokens.length);
              for (uint256 i = 0; i < tokens.length; ++i) {
                  // Because the iteration is bounded by `tokens.length`, which matches the EnumerableMap's length, we can use
                  // `unchecked_at` as we know `i` is a valid token index, saving storage reads.
                  (tokens[i], balances[i]) = poolBalances.unchecked_at(i);
              }
          }
          /**
           * @dev Returns the balance of a token in a General Pool.
           *
           * This function assumes `poolId` exists and corresponds to the General specialization setting.
           *
           * Requirements:
           *
           * - `token` must be registered in the Pool
           */
          function _getGeneralPoolBalance(bytes32 poolId, IERC20 token) internal view returns (bytes32) {
              EnumerableMap.IERC20ToBytes32Map storage poolBalances = _generalPoolsBalances[poolId];
              return _getGeneralPoolBalance(poolBalances, token);
          }
          /**
           * @dev Same as `_getGeneralPoolBalance` but using a Pool's storage pointer, which saves gas in repeated reads and
           * writes.
           */
          function _getGeneralPoolBalance(EnumerableMap.IERC20ToBytes32Map storage poolBalances, IERC20 token)
              private
              view
              returns (bytes32)
          {
              return poolBalances.get(token, Errors.TOKEN_NOT_REGISTERED);
          }
          /**
           * @dev Returns true if `token` is registered in a General Pool.
           *
           * This function assumes `poolId` exists and corresponds to the General specialization setting.
           */
          function _isGeneralPoolTokenRegistered(bytes32 poolId, IERC20 token) internal view returns (bool) {
              EnumerableMap.IERC20ToBytes32Map storage poolBalances = _generalPoolsBalances[poolId];
              return poolBalances.contains(token);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../../lib/helpers/BalancerErrors.sol";
      import "../../lib/openzeppelin/EnumerableSet.sol";
      import "../../lib/openzeppelin/IERC20.sol";
      import "./BalanceAllocation.sol";
      import "../PoolRegistry.sol";
      abstract contract MinimalSwapInfoPoolsBalance is PoolRegistry {
          using BalanceAllocation for bytes32;
          using EnumerableSet for EnumerableSet.AddressSet;
          // Data for Pools with the Minimal Swap Info specialization setting
          //
          // These Pools use the IMinimalSwapInfoPool interface, and so the Vault must read the balance of the two tokens
          // in the swap. The best solution is to use a mapping from token to balance, which lets us read or write any token's
          // balance in a single storage access.
          //
          // We also keep a set of registered tokens. Because tokens with non-zero balance are by definition registered, in
          // some balance getters we skip checking for token registration if a non-zero balance is found, saving gas by
          // performing a single read instead of two.
          mapping(bytes32 => mapping(IERC20 => bytes32)) internal _minimalSwapInfoPoolsBalances;
          mapping(bytes32 => EnumerableSet.AddressSet) internal _minimalSwapInfoPoolsTokens;
          /**
           * @dev Registers a list of tokens in a Minimal Swap Info Pool.
           *
           * This function assumes `poolId` exists and corresponds to the Minimal Swap Info specialization setting.
           *
           * Requirements:
           *
           * - `tokens` must not be registered in the Pool
           * - `tokens` must not contain duplicates
           */
          function _registerMinimalSwapInfoPoolTokens(bytes32 poolId, IERC20[] memory tokens) internal {
              EnumerableSet.AddressSet storage poolTokens = _minimalSwapInfoPoolsTokens[poolId];
              for (uint256 i = 0; i < tokens.length; ++i) {
                  bool added = poolTokens.add(address(tokens[i]));
                  _require(added, Errors.TOKEN_ALREADY_REGISTERED);
                  // Note that we don't initialize the balance mapping: the default value of zero corresponds to an empty
                  // balance.
              }
          }
          /**
           * @dev Deregisters a list of tokens in a Minimal Swap Info Pool.
           *
           * This function assumes `poolId` exists and corresponds to the Minimal Swap Info specialization setting.
           *
           * Requirements:
           *
           * - `tokens` must be registered in the Pool
           * - `tokens` must have zero balance in the Vault
           * - `tokens` must not contain duplicates
           */
          function _deregisterMinimalSwapInfoPoolTokens(bytes32 poolId, IERC20[] memory tokens) internal {
              EnumerableSet.AddressSet storage poolTokens = _minimalSwapInfoPoolsTokens[poolId];
              for (uint256 i = 0; i < tokens.length; ++i) {
                  IERC20 token = tokens[i];
                  _require(_minimalSwapInfoPoolsBalances[poolId][token].isZero(), Errors.NONZERO_TOKEN_BALANCE);
                  // For consistency with other Pool specialization settings, we explicitly reset the balance (which may have
                  // a non-zero last change block).
                  delete _minimalSwapInfoPoolsBalances[poolId][token];
                  bool removed = poolTokens.remove(address(token));
                  _require(removed, Errors.TOKEN_NOT_REGISTERED);
              }
          }
          /**
           * @dev Sets the balances of a Minimal Swap Info Pool's tokens to `balances`.
           *
           * WARNING: this assumes `balances` has the same length and order as the Pool's tokens.
           */
          function _setMinimalSwapInfoPoolBalances(
              bytes32 poolId,
              IERC20[] memory tokens,
              bytes32[] memory balances
          ) internal {
              for (uint256 i = 0; i < tokens.length; ++i) {
                  _minimalSwapInfoPoolsBalances[poolId][tokens[i]] = balances[i];
              }
          }
          /**
           * @dev Transforms `amount` of `token`'s balance in a Minimal Swap Info Pool from cash into managed.
           *
           * This function assumes `poolId` exists, corresponds to the Minimal Swap Info specialization setting, and that
           * `token` is registered for that Pool.
           */
          function _minimalSwapInfoPoolCashToManaged(
              bytes32 poolId,
              IERC20 token,
              uint256 amount
          ) internal {
              _updateMinimalSwapInfoPoolBalance(poolId, token, BalanceAllocation.cashToManaged, amount);
          }
          /**
           * @dev Transforms `amount` of `token`'s balance in a Minimal Swap Info Pool from managed into cash.
           *
           * This function assumes `poolId` exists, corresponds to the Minimal Swap Info specialization setting, and that
           * `token` is registered for that Pool.
           */
          function _minimalSwapInfoPoolManagedToCash(
              bytes32 poolId,
              IERC20 token,
              uint256 amount
          ) internal {
              _updateMinimalSwapInfoPoolBalance(poolId, token, BalanceAllocation.managedToCash, amount);
          }
          /**
           * @dev Sets `token`'s managed balance in a Minimal Swap Info Pool to `amount`.
           *
           * This function assumes `poolId` exists, corresponds to the Minimal Swap Info specialization setting, and that
           * `token` is registered for that Pool.
           *
           * Returns the managed balance delta as a result of this call.
           */
          function _setMinimalSwapInfoPoolManagedBalance(
              bytes32 poolId,
              IERC20 token,
              uint256 amount
          ) internal returns (int256) {
              return _updateMinimalSwapInfoPoolBalance(poolId, token, BalanceAllocation.setManaged, amount);
          }
          /**
           * @dev Sets `token`'s balance in a Minimal Swap Info Pool to the result of the `mutation` function when called with
           * the current balance and `amount`.
           *
           * This function assumes `poolId` exists, corresponds to the Minimal Swap Info specialization setting, and that
           * `token` is registered for that Pool.
           *
           * Returns the managed balance delta as a result of this call.
           */
          function _updateMinimalSwapInfoPoolBalance(
              bytes32 poolId,
              IERC20 token,
              function(bytes32, uint256) returns (bytes32) mutation,
              uint256 amount
          ) internal returns (int256) {
              bytes32 currentBalance = _getMinimalSwapInfoPoolBalance(poolId, token);
              bytes32 newBalance = mutation(currentBalance, amount);
              _minimalSwapInfoPoolsBalances[poolId][token] = newBalance;
              return newBalance.managedDelta(currentBalance);
          }
          /**
           * @dev Returns an array with all the tokens and balances in a Minimal Swap Info Pool. The order may change when
           * tokens are registered or deregistered.
           *
           * This function assumes `poolId` exists and corresponds to the Minimal Swap Info specialization setting.
           */
          function _getMinimalSwapInfoPoolTokens(bytes32 poolId)
              internal
              view
              returns (IERC20[] memory tokens, bytes32[] memory balances)
          {
              EnumerableSet.AddressSet storage poolTokens = _minimalSwapInfoPoolsTokens[poolId];
              tokens = new IERC20[](poolTokens.length());
              balances = new bytes32[](tokens.length);
              for (uint256 i = 0; i < tokens.length; ++i) {
                  // Because the iteration is bounded by `tokens.length`, which matches the EnumerableSet's length, we can use
                  // `unchecked_at` as we know `i` is a valid token index, saving storage reads.
                  IERC20 token = IERC20(poolTokens.unchecked_at(i));
                  tokens[i] = token;
                  balances[i] = _minimalSwapInfoPoolsBalances[poolId][token];
              }
          }
          /**
           * @dev Returns the balance of a token in a Minimal Swap Info Pool.
           *
           * Requirements:
           *
           * - `poolId` must be a Minimal Swap Info Pool
           * - `token` must be registered in the Pool
           */
          function _getMinimalSwapInfoPoolBalance(bytes32 poolId, IERC20 token) internal view returns (bytes32) {
              bytes32 balance = _minimalSwapInfoPoolsBalances[poolId][token];
              // A non-zero balance guarantees that the token is registered. If zero, we manually check if the token is
              // registered in the Pool. Token registration implies that the Pool is registered as well, which lets us save
              // gas by not performing the check.
              bool tokenRegistered = balance.isNotZero() || _minimalSwapInfoPoolsTokens[poolId].contains(address(token));
              if (!tokenRegistered) {
                  // The token might not be registered because the Pool itself is not registered. We check this to provide a
                  // more accurate revert reason.
                  _ensureRegisteredPool(poolId);
                  _revert(Errors.TOKEN_NOT_REGISTERED);
              }
              return balance;
          }
          /**
           * @dev Returns true if `token` is registered in a Minimal Swap Info Pool.
           *
           * This function assumes `poolId` exists and corresponds to the Minimal Swap Info specialization setting.
           */
          function _isMinimalSwapInfoPoolTokenRegistered(bytes32 poolId, IERC20 token) internal view returns (bool) {
              EnumerableSet.AddressSet storage poolTokens = _minimalSwapInfoPoolsTokens[poolId];
              return poolTokens.contains(address(token));
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../../lib/helpers/BalancerErrors.sol";
      import "../../lib/openzeppelin/IERC20.sol";
      import "./BalanceAllocation.sol";
      import "../PoolRegistry.sol";
      abstract contract TwoTokenPoolsBalance is PoolRegistry {
          using BalanceAllocation for bytes32;
          // Data for Pools with the Two Token specialization setting
          //
          // These are similar to the Minimal Swap Info Pool case (because the Pool only has two tokens, and therefore there
          // are only two balances to read), but there's a key difference in how data is stored. Keeping a set makes little
          // sense, as it will only ever hold two tokens, so we can just store those two directly.
          //
          // The gas savings associated with using these Pools come from how token balances are stored: cash amounts for token
          // A and token B are packed together, as are managed amounts. Because only cash changes in a swap, there's no need
          // to write to this second storage slot. A single last change block number for both tokens is stored with the packed
          // cash fields.
          struct TwoTokenPoolBalances {
              bytes32 sharedCash;
              bytes32 sharedManaged;
          }
          // We could just keep a mapping from Pool ID to TwoTokenSharedBalances, but there's an issue: we wouldn't know to
          // which tokens those balances correspond. This would mean having to also check which are registered with the Pool.
          //
          // What we do instead to save those storage reads is keep a nested mapping from the token pair hash to the balances
          // struct. The Pool only has two tokens, so only a single entry of this mapping is set (the one that corresponds to
          // that pair's hash).
          //
          // This has the trade-off of making Vault code that interacts with these Pools cumbersome: both balances must be
          // accessed at the same time by using both token addresses, and some logic is needed to determine how the pair hash
          // is computed. We do this by sorting the tokens, calling the token with the lowest numerical address value token A,
          // and the other one token B. In functions where the token arguments could be either A or B, we use X and Y instead.
          //
          // If users query a token pair containing an unregistered token, the Pool will generate a hash for a mapping entry
          // that was not set, and return zero balances. Non-zero balances are only possible if both tokens in the pair
          // are registered with the Pool, which means we don't have to check the TwoTokenPoolTokens struct, and can save
          // storage reads.
          struct TwoTokenPoolTokens {
              IERC20 tokenA;
              IERC20 tokenB;
              mapping(bytes32 => TwoTokenPoolBalances) balances;
          }
          mapping(bytes32 => TwoTokenPoolTokens) private _twoTokenPoolTokens;
          /**
           * @dev Registers tokens in a Two Token Pool.
           *
           * This function assumes `poolId` exists and corresponds to the Two Token specialization setting.
           *
           * Requirements:
           *
           * - `tokenX` and `tokenY` must not be the same
           * - The tokens must be ordered: tokenX < tokenY
           */
          function _registerTwoTokenPoolTokens(
              bytes32 poolId,
              IERC20 tokenX,
              IERC20 tokenY
          ) internal {
              // Not technically true since we didn't register yet, but this is consistent with the error messages of other
              // specialization settings.
              _require(tokenX != tokenY, Errors.TOKEN_ALREADY_REGISTERED);
              _require(tokenX < tokenY, Errors.UNSORTED_TOKENS);
              // A Two Token Pool with no registered tokens is identified by having zero addresses for tokens A and B.
              TwoTokenPoolTokens storage poolTokens = _twoTokenPoolTokens[poolId];
              _require(poolTokens.tokenA == IERC20(0) && poolTokens.tokenB == IERC20(0), Errors.TOKENS_ALREADY_SET);
              // Since tokenX < tokenY, tokenX is A and tokenY is B
              poolTokens.tokenA = tokenX;
              poolTokens.tokenB = tokenY;
              // Note that we don't initialize the balance mapping: the default value of zero corresponds to an empty
              // balance.
          }
          /**
           * @dev Deregisters tokens in a Two Token Pool.
           *
           * This function assumes `poolId` exists and corresponds to the Two Token specialization setting.
           *
           * Requirements:
           *
           * - `tokenX` and `tokenY` must be registered in the Pool
           * - both tokens must have zero balance in the Vault
           */
          function _deregisterTwoTokenPoolTokens(
              bytes32 poolId,
              IERC20 tokenX,
              IERC20 tokenY
          ) internal {
              (
                  bytes32 balanceA,
                  bytes32 balanceB,
                  TwoTokenPoolBalances storage poolBalances
              ) = _getTwoTokenPoolSharedBalances(poolId, tokenX, tokenY);
              _require(balanceA.isZero() && balanceB.isZero(), Errors.NONZERO_TOKEN_BALANCE);
              delete _twoTokenPoolTokens[poolId];
              // For consistency with other Pool specialization settings, we explicitly reset the packed cash field (which may
              // have a non-zero last change block).
              delete poolBalances.sharedCash;
          }
          /**
           * @dev Sets the cash balances of a Two Token Pool's tokens.
           *
           * WARNING: this assumes `tokenA` and `tokenB` are the Pool's two registered tokens, and are in the correct order.
           */
          function _setTwoTokenPoolCashBalances(
              bytes32 poolId,
              IERC20 tokenA,
              bytes32 balanceA,
              IERC20 tokenB,
              bytes32 balanceB
          ) internal {
              bytes32 pairHash = _getTwoTokenPairHash(tokenA, tokenB);
              TwoTokenPoolBalances storage poolBalances = _twoTokenPoolTokens[poolId].balances[pairHash];
              poolBalances.sharedCash = BalanceAllocation.toSharedCash(balanceA, balanceB);
          }
          /**
           * @dev Transforms `amount` of `token`'s balance in a Two Token Pool from cash into managed.
           *
           * This function assumes `poolId` exists, corresponds to the Two Token specialization setting, and that `token` is
           * registered for that Pool.
           */
          function _twoTokenPoolCashToManaged(
              bytes32 poolId,
              IERC20 token,
              uint256 amount
          ) internal {
              _updateTwoTokenPoolSharedBalance(poolId, token, BalanceAllocation.cashToManaged, amount);
          }
          /**
           * @dev Transforms `amount` of `token`'s balance in a Two Token Pool from managed into cash.
           *
           * This function assumes `poolId` exists, corresponds to the Two Token specialization setting, and that `token` is
           * registered for that Pool.
           */
          function _twoTokenPoolManagedToCash(
              bytes32 poolId,
              IERC20 token,
              uint256 amount
          ) internal {
              _updateTwoTokenPoolSharedBalance(poolId, token, BalanceAllocation.managedToCash, amount);
          }
          /**
           * @dev Sets `token`'s managed balance in a Two Token Pool to `amount`.
           *
           * This function assumes `poolId` exists, corresponds to the Two Token specialization setting, and that `token` is
           * registered for that Pool.
           *
           * Returns the managed balance delta as a result of this call.
           */
          function _setTwoTokenPoolManagedBalance(
              bytes32 poolId,
              IERC20 token,
              uint256 amount
          ) internal returns (int256) {
              return _updateTwoTokenPoolSharedBalance(poolId, token, BalanceAllocation.setManaged, amount);
          }
          /**
           * @dev Sets `token`'s balance in a Two Token Pool to the result of the `mutation` function when called with
           * the current balance and `amount`.
           *
           * This function assumes `poolId` exists, corresponds to the Two Token specialization setting, and that `token` is
           * registered for that Pool.
           *
           * Returns the managed balance delta as a result of this call.
           */
          function _updateTwoTokenPoolSharedBalance(
              bytes32 poolId,
              IERC20 token,
              function(bytes32, uint256) returns (bytes32) mutation,
              uint256 amount
          ) private returns (int256) {
              (
                  TwoTokenPoolBalances storage balances,
                  IERC20 tokenA,
                  bytes32 balanceA,
                  ,
                  bytes32 balanceB
              ) = _getTwoTokenPoolBalances(poolId);
              int256 delta;
              if (token == tokenA) {
                  bytes32 newBalance = mutation(balanceA, amount);
                  delta = newBalance.managedDelta(balanceA);
                  balanceA = newBalance;
              } else {
                  // token == tokenB
                  bytes32 newBalance = mutation(balanceB, amount);
                  delta = newBalance.managedDelta(balanceB);
                  balanceB = newBalance;
              }
              balances.sharedCash = BalanceAllocation.toSharedCash(balanceA, balanceB);
              balances.sharedManaged = BalanceAllocation.toSharedManaged(balanceA, balanceB);
              return delta;
          }
          /*
           * @dev Returns an array with all the tokens and balances in a Two Token Pool. The order may change when
           * tokens are registered or deregistered.
           *
           * This function assumes `poolId` exists and corresponds to the Two Token specialization setting.
           */
          function _getTwoTokenPoolTokens(bytes32 poolId)
              internal
              view
              returns (IERC20[] memory tokens, bytes32[] memory balances)
          {
              (, IERC20 tokenA, bytes32 balanceA, IERC20 tokenB, bytes32 balanceB) = _getTwoTokenPoolBalances(poolId);
              // Both tokens will either be zero (if unregistered) or non-zero (if registered), but we keep the full check for
              // clarity.
              if (tokenA == IERC20(0) || tokenB == IERC20(0)) {
                  return (new IERC20[](0), new bytes32[](0));
              }
              // Note that functions relying on this getter expect tokens to be properly ordered, so we use the (A, B)
              // ordering.
              tokens = new IERC20[](2);
              tokens[0] = tokenA;
              tokens[1] = tokenB;
              balances = new bytes32[](2);
              balances[0] = balanceA;
              balances[1] = balanceB;
          }
          /**
           * @dev Same as `_getTwoTokenPoolTokens`, except it returns the two tokens and balances directly instead of using
           * an array, as well as a storage pointer to the `TwoTokenPoolBalances` struct, which can be used to update it
           * without having to recompute the pair hash and storage slot.
           */
          function _getTwoTokenPoolBalances(bytes32 poolId)
              private
              view
              returns (
                  TwoTokenPoolBalances storage poolBalances,
                  IERC20 tokenA,
                  bytes32 balanceA,
                  IERC20 tokenB,
                  bytes32 balanceB
              )
          {
              TwoTokenPoolTokens storage poolTokens = _twoTokenPoolTokens[poolId];
              tokenA = poolTokens.tokenA;
              tokenB = poolTokens.tokenB;
              bytes32 pairHash = _getTwoTokenPairHash(tokenA, tokenB);
              poolBalances = poolTokens.balances[pairHash];
              bytes32 sharedCash = poolBalances.sharedCash;
              bytes32 sharedManaged = poolBalances.sharedManaged;
              balanceA = BalanceAllocation.fromSharedToBalanceA(sharedCash, sharedManaged);
              balanceB = BalanceAllocation.fromSharedToBalanceB(sharedCash, sharedManaged);
          }
          /**
           * @dev Returns the balance of a token in a Two Token Pool.
           *
           * This function assumes `poolId` exists and corresponds to the General specialization setting.
           *
           * This function is convenient but not particularly gas efficient, and should be avoided during gas-sensitive
           * operations, such as swaps. For those, _getTwoTokenPoolSharedBalances provides a more flexible interface.
           *
           * Requirements:
           *
           * - `token` must be registered in the Pool
           */
          function _getTwoTokenPoolBalance(bytes32 poolId, IERC20 token) internal view returns (bytes32) {
              // We can't just read the balance of token, because we need to know the full pair in order to compute the pair
              // hash and access the balance mapping. We therefore rely on `_getTwoTokenPoolBalances`.
              (, IERC20 tokenA, bytes32 balanceA, IERC20 tokenB, bytes32 balanceB) = _getTwoTokenPoolBalances(poolId);
              if (token == tokenA) {
                  return balanceA;
              } else if (token == tokenB) {
                  return balanceB;
              } else {
                  _revert(Errors.TOKEN_NOT_REGISTERED);
              }
          }
          /**
           * @dev Returns the balance of the two tokens in a Two Token Pool.
           *
           * The returned balances are those of token A and token B, where token A is the lowest of token X and token Y, and
           * token B the other.
           *
           * This function also returns a storage pointer to the TwoTokenPoolBalances struct associated with the token pair,
           * which can be used to update it without having to recompute the pair hash and storage slot.
           *
           * Requirements:
           *
           * - `poolId` must be a Minimal Swap Info Pool
           * - `tokenX` and `tokenY` must be registered in the Pool
           */
          function _getTwoTokenPoolSharedBalances(
              bytes32 poolId,
              IERC20 tokenX,
              IERC20 tokenY
          )
              internal
              view
              returns (
                  bytes32 balanceA,
                  bytes32 balanceB,
                  TwoTokenPoolBalances storage poolBalances
              )
          {
              (IERC20 tokenA, IERC20 tokenB) = _sortTwoTokens(tokenX, tokenY);
              bytes32 pairHash = _getTwoTokenPairHash(tokenA, tokenB);
              poolBalances = _twoTokenPoolTokens[poolId].balances[pairHash];
              // Because we're reading balances using the pair hash, if either token X or token Y is not registered then
              // *both* balance entries will be zero.
              bytes32 sharedCash = poolBalances.sharedCash;
              bytes32 sharedManaged = poolBalances.sharedManaged;
              // A non-zero balance guarantees that both tokens are registered. If zero, we manually check whether each
              // token is registered in the Pool. Token registration implies that the Pool is registered as well, which
              // lets us save gas by not performing the check.
              bool tokensRegistered = sharedCash.isNotZero() ||
                  sharedManaged.isNotZero() ||
                  (_isTwoTokenPoolTokenRegistered(poolId, tokenA) && _isTwoTokenPoolTokenRegistered(poolId, tokenB));
              if (!tokensRegistered) {
                  // The tokens might not be registered because the Pool itself is not registered. We check this to provide a
                  // more accurate revert reason.
                  _ensureRegisteredPool(poolId);
                  _revert(Errors.TOKEN_NOT_REGISTERED);
              }
              balanceA = BalanceAllocation.fromSharedToBalanceA(sharedCash, sharedManaged);
              balanceB = BalanceAllocation.fromSharedToBalanceB(sharedCash, sharedManaged);
          }
          /**
           * @dev Returns true if `token` is registered in a Two Token Pool.
           *
           * This function assumes `poolId` exists and corresponds to the Two Token specialization setting.
           */
          function _isTwoTokenPoolTokenRegistered(bytes32 poolId, IERC20 token) internal view returns (bool) {
              TwoTokenPoolTokens storage poolTokens = _twoTokenPoolTokens[poolId];
              // The zero address can never be a registered token.
              return (token == poolTokens.tokenA || token == poolTokens.tokenB) && token != IERC20(0);
          }
          /**
           * @dev Returns the hash associated with a given token pair.
           */
          function _getTwoTokenPairHash(IERC20 tokenA, IERC20 tokenB) private pure returns (bytes32) {
              return keccak256(abi.encodePacked(tokenA, tokenB));
          }
          /**
           * @dev Sorts two tokens in ascending order, returning them as a (tokenA, tokenB) tuple.
           */
          function _sortTwoTokens(IERC20 tokenX, IERC20 tokenY) private pure returns (IERC20, IERC20) {
              return tokenX < tokenY ? (tokenX, tokenY) : (tokenY, tokenX);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../lib/math/Math.sol";
      import "../lib/helpers/BalancerErrors.sol";
      import "../lib/openzeppelin/IERC20.sol";
      import "../lib/helpers/AssetHelpers.sol";
      import "../lib/openzeppelin/SafeERC20.sol";
      import "../lib/openzeppelin/Address.sol";
      import "./interfaces/IWETH.sol";
      import "./interfaces/IAsset.sol";
      import "./interfaces/IVault.sol";
      abstract contract AssetTransfersHandler is AssetHelpers {
          using SafeERC20 for IERC20;
          using Address for address payable;
          /**
           * @dev Receives `amount` of `asset` from `sender`. If `fromInternalBalance` is true, it first withdraws as much
           * as possible from Internal Balance, then transfers any remaining amount.
           *
           * If `asset` is ETH, `fromInternalBalance` must be false (as ETH cannot be held as internal balance), and the funds
           * will be wrapped into WETH.
           *
           * WARNING: this function does not check that the contract caller has actually supplied any ETH - it is up to the
           * caller of this function to check that this is true to prevent the Vault from using its own ETH (though the Vault
           * typically doesn't hold any).
           */
          function _receiveAsset(
              IAsset asset,
              uint256 amount,
              address sender,
              bool fromInternalBalance
          ) internal {
              if (amount == 0) {
                  return;
              }
              if (_isETH(asset)) {
                  _require(!fromInternalBalance, Errors.INVALID_ETH_INTERNAL_BALANCE);
                  // The ETH amount to receive is deposited into the WETH contract, which will in turn mint WETH for
                  // the Vault at a 1:1 ratio.
                  // A check for this condition is also introduced by the compiler, but this one provides a revert reason.
                  // Note we're checking for the Vault's total balance, *not* ETH sent in this transaction.
                  _require(address(this).balance >= amount, Errors.INSUFFICIENT_ETH);
                  _WETH().deposit{ value: amount }();
              } else {
                  IERC20 token = _asIERC20(asset);
                  if (fromInternalBalance) {
                      // We take as many tokens from Internal Balance as possible: any remaining amounts will be transferred.
                      uint256 deductedBalance = _decreaseInternalBalance(sender, token, amount, true);
                      // Because `deductedBalance` will be always the lesser of the current internal balance
                      // and the amount to decrease, it is safe to perform unchecked arithmetic.
                      amount -= deductedBalance;
                  }
                  if (amount > 0) {
                      token.safeTransferFrom(sender, address(this), amount);
                  }
              }
          }
          /**
           * @dev Sends `amount` of `asset` to `recipient`. If `toInternalBalance` is true, the asset is deposited as Internal
           * Balance instead of being transferred.
           *
           * If `asset` is ETH, `toInternalBalance` must be false (as ETH cannot be held as internal balance), and the funds
           * are instead sent directly after unwrapping WETH.
           */
          function _sendAsset(
              IAsset asset,
              uint256 amount,
              address payable recipient,
              bool toInternalBalance
          ) internal {
              if (amount == 0) {
                  return;
              }
              if (_isETH(asset)) {
                  // Sending ETH is not as involved as receiving it: the only special behavior is it cannot be
                  // deposited to Internal Balance.
                  _require(!toInternalBalance, Errors.INVALID_ETH_INTERNAL_BALANCE);
                  // First, the Vault withdraws deposited ETH from the WETH contract, by burning the same amount of WETH
                  // from the Vault. This receipt will be handled by the Vault's `receive`.
                  _WETH().withdraw(amount);
                  // Then, the withdrawn ETH is sent to the recipient.
                  recipient.sendValue(amount);
              } else {
                  IERC20 token = _asIERC20(asset);
                  if (toInternalBalance) {
                      _increaseInternalBalance(recipient, token, amount);
                  } else {
                      token.safeTransfer(recipient, amount);
                  }
              }
          }
          /**
           * @dev Returns excess ETH back to the contract caller, assuming `amountUsed` has been spent. Reverts
           * if the caller sent less ETH than `amountUsed`.
           *
           * Because the caller might not know exactly how much ETH a Vault action will require, they may send extra.
           * Note that this excess value is returned *to the contract caller* (msg.sender). If caller and e.g. swap sender are
           * not the same (because the caller is a relayer for the sender), then it is up to the caller to manage this
           * returned ETH.
           */
          function _handleRemainingEth(uint256 amountUsed) internal {
              _require(msg.value >= amountUsed, Errors.INSUFFICIENT_ETH);
              uint256 excess = msg.value - amountUsed;
              if (excess > 0) {
                  msg.sender.sendValue(excess);
              }
          }
          /**
           * @dev Enables the Vault to receive ETH. This is required for it to be able to unwrap WETH, which sends ETH to the
           * caller.
           *
           * Any ETH sent to the Vault outside of the WETH unwrapping mechanism would be forever locked inside the Vault, so
           * we prevent that from happening. Other mechanisms used to send ETH to the Vault (such as being the recipient of an
           * ETH swap, Pool exit or withdrawal, contract self-destruction, or receiving the block mining reward) will result
           * in locked funds, but are not otherwise a security or soundness issue. This check only exists as an attempt to
           * prevent user error.
           */
          receive() external payable {
              _require(msg.sender == address(_WETH()), Errors.ETH_TRANSFER);
          }
          // This contract uses virtual internal functions instead of inheriting from the modules that implement them (in
          // this case UserBalance) in order to decouple it from the rest of the system and enable standalone testing by
          // implementing these with mocks.
          function _increaseInternalBalance(
              address account,
              IERC20 token,
              uint256 amount
          ) internal virtual;
          function _decreaseInternalBalance(
              address account,
              IERC20 token,
              uint256 amount,
              bool capped
          ) internal virtual returns (uint256);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "../openzeppelin/IERC20.sol";
      import "../../vault/interfaces/IAsset.sol";
      import "../../vault/interfaces/IWETH.sol";
      abstract contract AssetHelpers {
          // solhint-disable-next-line var-name-mixedcase
          IWETH private immutable _weth;
          // Sentinel value used to indicate WETH with wrapping/unwrapping semantics. The zero address is a good choice for
          // multiple reasons: it is cheap to pass as a calldata argument, it is a known invalid token and non-contract, and
          // it is an address Pools cannot register as a token.
          address private constant _ETH = address(0);
          constructor(IWETH weth) {
              _weth = weth;
          }
          // solhint-disable-next-line func-name-mixedcase
          function _WETH() internal view returns (IWETH) {
              return _weth;
          }
          /**
           * @dev Returns true if `asset` is the sentinel value that represents ETH.
           */
          function _isETH(IAsset asset) internal pure returns (bool) {
              return address(asset) == _ETH;
          }
          /**
           * @dev Translates `asset` into an equivalent IERC20 token address. If `asset` represents ETH, it will be translated
           * to the WETH contract.
           */
          function _translateToIERC20(IAsset asset) internal view returns (IERC20) {
              return _isETH(asset) ? _WETH() : _asIERC20(asset);
          }
          /**
           * @dev Same as `_translateToIERC20(IAsset)`, but for an entire array.
           */
          function _translateToIERC20(IAsset[] memory assets) internal view returns (IERC20[] memory) {
              IERC20[] memory tokens = new IERC20[](assets.length);
              for (uint256 i = 0; i < assets.length; ++i) {
                  tokens[i] = _translateToIERC20(assets[i]);
              }
              return tokens;
          }
          /**
           * @dev Interprets `asset` as an IERC20 token. This function should only be called on `asset` if `_isETH` previously
           * returned false for it, that is, if `asset` is guaranteed not to be the ETH sentinel value.
           */
          function _asIERC20(IAsset asset) internal pure returns (IERC20) {
              return IERC20(address(asset));
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      import "../helpers/BalancerErrors.sol";
      /**
       * @dev Collection of functions related to the address type
       */
      library Address {
          /**
           * @dev Returns true if `account` is a contract.
           *
           * [IMPORTANT]
           * ====
           * It is unsafe to assume that an address for which this function returns
           * false is an externally-owned account (EOA) and not a contract.
           *
           * Among others, `isContract` will return false for the following
           * types of addresses:
           *
           *  - an externally-owned account
           *  - a contract in construction
           *  - an address where a contract will be created
           *  - an address where a contract lived, but was destroyed
           * ====
           */
          function isContract(address account) internal view returns (bool) {
              // This method relies on extcodesize, which returns 0 for contracts in
              // construction, since the code is only stored at the end of the
              // constructor execution.
              uint256 size;
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  size := extcodesize(account)
              }
              return size > 0;
          }
          /**
           * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
           * `recipient`, forwarding all available gas and reverting on errors.
           *
           * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
           * of certain opcodes, possibly making contracts go over the 2300 gas limit
           * imposed by `transfer`, making them unable to receive funds via
           * `transfer`. {sendValue} removes this limitation.
           *
           * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
           *
           * IMPORTANT: because control is transferred to `recipient`, care must be
           * taken to not create reentrancy vulnerabilities. Consider using
           * {ReentrancyGuard} or the
           * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
           */
          function sendValue(address payable recipient, uint256 amount) internal {
              _require(address(this).balance >= amount, Errors.ADDRESS_INSUFFICIENT_BALANCE);
              // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
              (bool success, ) = recipient.call{ value: amount }("");
              _require(success, Errors.ADDRESS_CANNOT_SEND_VALUE);
          }
      }
      

      File 2 of 5: ProtocolFeesCollector
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../lib/openzeppelin/IERC20.sol";
      import "../lib/helpers/InputHelpers.sol";
      import "../lib/helpers/Authentication.sol";
      import "../lib/openzeppelin/ReentrancyGuard.sol";
      import "../lib/openzeppelin/SafeERC20.sol";
      import "./interfaces/IVault.sol";
      import "./interfaces/IAuthorizer.sol";
      /**
       * @dev This an auxiliary contract to the Vault, deployed by it during construction. It offloads some of the tasks the
       * Vault performs to reduce its overall bytecode size.
       *
       * The current values for all protocol fee percentages are stored here, and any tokens charged as protocol fees are
       * sent to this contract, where they may be withdrawn by authorized entities. All authorization tasks are delegated
       * to the Vault's own authorizer.
       */
      contract ProtocolFeesCollector is Authentication, ReentrancyGuard {
          using SafeERC20 for IERC20;
          // Absolute maximum fee percentages (1e18 = 100%, 1e16 = 1%).
          uint256 private constant _MAX_PROTOCOL_SWAP_FEE_PERCENTAGE = 50e16; // 50%
          uint256 private constant _MAX_PROTOCOL_FLASH_LOAN_FEE_PERCENTAGE = 1e16; // 1%
          IVault public immutable vault;
          // All fee percentages are 18-decimal fixed point numbers.
          // The swap fee is charged whenever a swap occurs, as a percentage of the fee charged by the Pool. These are not
          // actually charged on each individual swap: the `Vault` relies on the Pools being honest and reporting fees due
          // when users join and exit them.
          uint256 private _swapFeePercentage;
          // The flash loan fee is charged whenever a flash loan occurs, as a percentage of the tokens lent.
          uint256 private _flashLoanFeePercentage;
          event SwapFeePercentageChanged(uint256 newSwapFeePercentage);
          event FlashLoanFeePercentageChanged(uint256 newFlashLoanFeePercentage);
          constructor(IVault _vault)
              // The ProtocolFeesCollector is a singleton, so it simply uses its own address to disambiguate action
              // identifiers.
              Authentication(bytes32(uint256(address(this))))
          {
              vault = _vault;
          }
          function withdrawCollectedFees(
              IERC20[] calldata tokens,
              uint256[] calldata amounts,
              address recipient
          ) external nonReentrant authenticate {
              InputHelpers.ensureInputLengthMatch(tokens.length, amounts.length);
              for (uint256 i = 0; i < tokens.length; ++i) {
                  IERC20 token = tokens[i];
                  uint256 amount = amounts[i];
                  token.safeTransfer(recipient, amount);
              }
          }
          function setSwapFeePercentage(uint256 newSwapFeePercentage) external authenticate {
              _require(newSwapFeePercentage <= _MAX_PROTOCOL_SWAP_FEE_PERCENTAGE, Errors.SWAP_FEE_PERCENTAGE_TOO_HIGH);
              _swapFeePercentage = newSwapFeePercentage;
              emit SwapFeePercentageChanged(newSwapFeePercentage);
          }
          function setFlashLoanFeePercentage(uint256 newFlashLoanFeePercentage) external authenticate {
              _require(
                  newFlashLoanFeePercentage <= _MAX_PROTOCOL_FLASH_LOAN_FEE_PERCENTAGE,
                  Errors.FLASH_LOAN_FEE_PERCENTAGE_TOO_HIGH
              );
              _flashLoanFeePercentage = newFlashLoanFeePercentage;
              emit FlashLoanFeePercentageChanged(newFlashLoanFeePercentage);
          }
          function getSwapFeePercentage() external view returns (uint256) {
              return _swapFeePercentage;
          }
          function getFlashLoanFeePercentage() external view returns (uint256) {
              return _flashLoanFeePercentage;
          }
          function getCollectedFeeAmounts(IERC20[] memory tokens) external view returns (uint256[] memory feeAmounts) {
              feeAmounts = new uint256[](tokens.length);
              for (uint256 i = 0; i < tokens.length; ++i) {
                  feeAmounts[i] = tokens[i].balanceOf(address(this));
              }
          }
          function getAuthorizer() external view returns (IAuthorizer) {
              return _getAuthorizer();
          }
          function _canPerform(bytes32 actionId, address account) internal view override returns (bool) {
              return _getAuthorizer().canPerform(actionId, account, address(this));
          }
          function _getAuthorizer() internal view returns (IAuthorizer) {
              return vault.getAuthorizer();
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      /**
       * @dev Interface of the ERC20 standard as defined in the EIP.
       */
      interface IERC20 {
          /**
           * @dev Returns the amount of tokens in existence.
           */
          function totalSupply() external view returns (uint256);
          /**
           * @dev Returns the amount of tokens owned by `account`.
           */
          function balanceOf(address account) external view returns (uint256);
          /**
           * @dev Moves `amount` tokens from the caller's account to `recipient`.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * Emits a {Transfer} event.
           */
          function transfer(address recipient, uint256 amount) external returns (bool);
          /**
           * @dev Returns the remaining number of tokens that `spender` will be
           * allowed to spend on behalf of `owner` through {transferFrom}. This is
           * zero by default.
           *
           * This value changes when {approve} or {transferFrom} are called.
           */
          function allowance(address owner, address spender) external view returns (uint256);
          /**
           * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * IMPORTANT: Beware that changing an allowance with this method brings the risk
           * that someone may use both the old and the new allowance by unfortunate
           * transaction ordering. One possible solution to mitigate this race
           * condition is to first reduce the spender's allowance to 0 and set the
           * desired value afterwards:
           * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
           *
           * Emits an {Approval} event.
           */
          function approve(address spender, uint256 amount) external returns (bool);
          /**
           * @dev Moves `amount` tokens from `sender` to `recipient` using the
           * allowance mechanism. `amount` is then deducted from the caller's
           * allowance.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * Emits a {Transfer} event.
           */
          function transferFrom(
              address sender,
              address recipient,
              uint256 amount
          ) external returns (bool);
          /**
           * @dev Emitted when `value` tokens are moved from one account (`from`) to
           * another (`to`).
           *
           * Note that `value` may be zero.
           */
          event Transfer(address indexed from, address indexed to, uint256 value);
          /**
           * @dev Emitted when the allowance of a `spender` for an `owner` is set by
           * a call to {approve}. `value` is the new allowance.
           */
          event Approval(address indexed owner, address indexed spender, uint256 value);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "../openzeppelin/IERC20.sol";
      import "./BalancerErrors.sol";
      import "../../vault/interfaces/IAsset.sol";
      library InputHelpers {
          function ensureInputLengthMatch(uint256 a, uint256 b) internal pure {
              _require(a == b, Errors.INPUT_LENGTH_MISMATCH);
          }
          function ensureInputLengthMatch(
              uint256 a,
              uint256 b,
              uint256 c
          ) internal pure {
              _require(a == b && b == c, Errors.INPUT_LENGTH_MISMATCH);
          }
          function ensureArrayIsSorted(IAsset[] memory array) internal pure {
              address[] memory addressArray;
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  addressArray := array
              }
              ensureArrayIsSorted(addressArray);
          }
          function ensureArrayIsSorted(IERC20[] memory array) internal pure {
              address[] memory addressArray;
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  addressArray := array
              }
              ensureArrayIsSorted(addressArray);
          }
          function ensureArrayIsSorted(address[] memory array) internal pure {
              if (array.length < 2) {
                  return;
              }
              address previous = array[0];
              for (uint256 i = 1; i < array.length; ++i) {
                  address current = array[i];
                  _require(previous < current, Errors.UNSORTED_ARRAY);
                  previous = current;
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "./BalancerErrors.sol";
      import "./IAuthentication.sol";
      /**
       * @dev Building block for performing access control on external functions.
       *
       * This contract is used via the `authenticate` modifier (or the `_authenticateCaller` function), which can be applied
       * to external functions to only make them callable by authorized accounts.
       *
       * Derived contracts must implement the `_canPerform` function, which holds the actual access control logic.
       */
      abstract contract Authentication is IAuthentication {
          bytes32 private immutable _actionIdDisambiguator;
          /**
           * @dev The main purpose of the `actionIdDisambiguator` is to prevent accidental function selector collisions in
           * multi contract systems.
           *
           * There are two main uses for it:
           *  - if the contract is a singleton, any unique identifier can be used to make the associated action identifiers
           *    unique. The contract's own address is a good option.
           *  - if the contract belongs to a family that shares action identifiers for the same functions, an identifier
           *    shared by the entire family (and no other contract) should be used instead.
           */
          constructor(bytes32 actionIdDisambiguator) {
              _actionIdDisambiguator = actionIdDisambiguator;
          }
          /**
           * @dev Reverts unless the caller is allowed to call this function. Should only be applied to external functions.
           */
          modifier authenticate() {
              _authenticateCaller();
              _;
          }
          /**
           * @dev Reverts unless the caller is allowed to call the entry point function.
           */
          function _authenticateCaller() internal view {
              bytes32 actionId = getActionId(msg.sig);
              _require(_canPerform(actionId, msg.sender), Errors.SENDER_NOT_ALLOWED);
          }
          function getActionId(bytes4 selector) public view override returns (bytes32) {
              // Each external function is dynamically assigned an action identifier as the hash of the disambiguator and the
              // function selector. Disambiguation is necessary to avoid potential collisions in the function selectors of
              // multiple contracts.
              return keccak256(abi.encodePacked(_actionIdDisambiguator, selector));
          }
          function _canPerform(bytes32 actionId, address user) internal view virtual returns (bool);
      }
      // SPDX-License-Identifier: MIT
      // Based on the ReentrancyGuard library from OpenZeppelin Contracts, altered to reduce bytecode size.
      // Modifier code is inlined by the compiler, which causes its code to appear multiple times in the codebase. By using
      // private functions, we achieve the same end result with slightly higher runtime gas costs, but reduced bytecode size.
      pragma solidity ^0.7.0;
      import "../helpers/BalancerErrors.sol";
      /**
       * @dev Contract module that helps prevent reentrant calls to a function.
       *
       * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
       * available, which can be applied to functions to make sure there are no nested
       * (reentrant) calls to them.
       *
       * Note that because there is a single `nonReentrant` guard, functions marked as
       * `nonReentrant` may not call one another. This can be worked around by making
       * those functions `private`, and then adding `external` `nonReentrant` entry
       * points to them.
       *
       * TIP: If you would like to learn more about reentrancy and alternative ways
       * to protect against it, check out our blog post
       * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
       */
      abstract contract ReentrancyGuard {
          // Booleans are more expensive than uint256 or any type that takes up a full
          // word because each write operation emits an extra SLOAD to first read the
          // slot's contents, replace the bits taken up by the boolean, and then write
          // back. This is the compiler's defense against contract upgrades and
          // pointer aliasing, and it cannot be disabled.
          // The values being non-zero value makes deployment a bit more expensive,
          // but in exchange the refund on every call to nonReentrant will be lower in
          // amount. Since refunds are capped to a percentage of the total
          // transaction's gas, it is best to keep them low in cases like this one, to
          // increase the likelihood of the full refund coming into effect.
          uint256 private constant _NOT_ENTERED = 1;
          uint256 private constant _ENTERED = 2;
          uint256 private _status;
          constructor() {
              _status = _NOT_ENTERED;
          }
          /**
           * @dev Prevents a contract from calling itself, directly or indirectly.
           * Calling a `nonReentrant` function from another `nonReentrant`
           * function is not supported. It is possible to prevent this from happening
           * by making the `nonReentrant` function external, and make it call a
           * `private` function that does the actual work.
           */
          modifier nonReentrant() {
              _enterNonReentrant();
              _;
              _exitNonReentrant();
          }
          function _enterNonReentrant() private {
              // On the first call to nonReentrant, _status will be _NOT_ENTERED
              _require(_status != _ENTERED, Errors.REENTRANCY);
              // Any calls to nonReentrant after this point will fail
              _status = _ENTERED;
          }
          function _exitNonReentrant() private {
              // By storing the original value once again, a refund is triggered (see
              // https://eips.ethereum.org/EIPS/eip-2200)
              _status = _NOT_ENTERED;
          }
      }
      // SPDX-License-Identifier: MIT
      // Based on the ReentrancyGuard library from OpenZeppelin Contracts, altered to reduce gas costs.
      // The `safeTransfer` and `safeTransferFrom` functions assume that `token` is a contract (an account with code), and
      // work differently from the OpenZeppelin version if it is not.
      pragma solidity ^0.7.0;
      import "../helpers/BalancerErrors.sol";
      import "./IERC20.sol";
      /**
       * @title SafeERC20
       * @dev Wrappers around ERC20 operations that throw on failure (when the token
       * contract returns false). Tokens that return no value (and instead revert or
       * throw on failure) are also supported, non-reverting calls are assumed to be
       * successful.
       * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
       * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
       */
      library SafeERC20 {
          function safeTransfer(
              IERC20 token,
              address to,
              uint256 value
          ) internal {
              _callOptionalReturn(address(token), abi.encodeWithSelector(token.transfer.selector, to, value));
          }
          function safeTransferFrom(
              IERC20 token,
              address from,
              address to,
              uint256 value
          ) internal {
              _callOptionalReturn(address(token), abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
          }
          /**
           * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
           * on the return value: the return value is optional (but if data is returned, it must not be false).
           *
           * WARNING: `token` is assumed to be a contract: calls to EOAs will *not* revert.
           */
          function _callOptionalReturn(address token, bytes memory data) private {
              // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
              // we're implementing it ourselves.
              (bool success, bytes memory returndata) = token.call(data);
              // If the low-level call didn't succeed we return whatever was returned from it.
              assembly {
                  if eq(success, 0) {
                      returndatacopy(0, 0, returndatasize())
                      revert(0, returndatasize())
                  }
              }
              // Finally we check the returndata size is either zero or true - note that this check will always pass for EOAs
              _require(returndata.length == 0 || abi.decode(returndata, (bool)), Errors.SAFE_ERC20_CALL_FAILED);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma experimental ABIEncoderV2;
      import "../../lib/openzeppelin/IERC20.sol";
      import "./IWETH.sol";
      import "./IAsset.sol";
      import "./IAuthorizer.sol";
      import "./IFlashLoanRecipient.sol";
      import "../ProtocolFeesCollector.sol";
      import "../../lib/helpers/ISignaturesValidator.sol";
      import "../../lib/helpers/ITemporarilyPausable.sol";
      pragma solidity ^0.7.0;
      /**
       * @dev Full external interface for the Vault core contract - no external or public methods exist in the contract that
       * don't override one of these declarations.
       */
      interface IVault is ISignaturesValidator, ITemporarilyPausable {
          // Generalities about the Vault:
          //
          // - Whenever documentation refers to 'tokens', it strictly refers to ERC20-compliant token contracts. Tokens are
          // transferred out of the Vault by calling the `IERC20.transfer` function, and transferred in by calling
          // `IERC20.transferFrom`. In these cases, the sender must have previously allowed the Vault to use their tokens by
          // calling `IERC20.approve`. The only deviation from the ERC20 standard that is supported is functions not returning
          // a boolean value: in these scenarios, a non-reverting call is assumed to be successful.
          //
          // - All non-view functions in the Vault are non-reentrant: calling them while another one is mid-execution (e.g.
          // while execution control is transferred to a token contract during a swap) will result in a revert. View
          // functions can be called in a re-reentrant way, but doing so might cause them to return inconsistent results.
          // Contracts calling view functions in the Vault must make sure the Vault has not already been entered.
          //
          // - View functions revert if referring to either unregistered Pools, or unregistered tokens for registered Pools.
          // Authorizer
          //
          // Some system actions are permissioned, like setting and collecting protocol fees. This permissioning system exists
          // outside of the Vault in the Authorizer contract: the Vault simply calls the Authorizer to check if the caller
          // can perform a given action.
          /**
           * @dev Returns the Vault's Authorizer.
           */
          function getAuthorizer() external view returns (IAuthorizer);
          /**
           * @dev Sets a new Authorizer for the Vault. The caller must be allowed by the current Authorizer to do this.
           *
           * Emits an `AuthorizerChanged` event.
           */
          function setAuthorizer(IAuthorizer newAuthorizer) external;
          /**
           * @dev Emitted when a new authorizer is set by `setAuthorizer`.
           */
          event AuthorizerChanged(IAuthorizer indexed newAuthorizer);
          // Relayers
          //
          // Additionally, it is possible for an account to perform certain actions on behalf of another one, using their
          // Vault ERC20 allowance and Internal Balance. These accounts are said to be 'relayers' for these Vault functions,
          // and are expected to be smart contracts with sound authentication mechanisms. For an account to be able to wield
          // this power, two things must occur:
          //  - The Authorizer must grant the account the permission to be a relayer for the relevant Vault function. This
          //    means that Balancer governance must approve each individual contract to act as a relayer for the intended
          //    functions.
          //  - Each user must approve the relayer to act on their behalf.
          // This double protection means users cannot be tricked into approving malicious relayers (because they will not
          // have been allowed by the Authorizer via governance), nor can malicious relayers approved by a compromised
          // Authorizer or governance drain user funds, since they would also need to be approved by each individual user.
          /**
           * @dev Returns true if `user` has approved `relayer` to act as a relayer for them.
           */
          function hasApprovedRelayer(address user, address relayer) external view returns (bool);
          /**
           * @dev Allows `relayer` to act as a relayer for `sender` if `approved` is true, and disallows it otherwise.
           *
           * Emits a `RelayerApprovalChanged` event.
           */
          function setRelayerApproval(
              address sender,
              address relayer,
              bool approved
          ) external;
          /**
           * @dev Emitted every time a relayer is approved or disapproved by `setRelayerApproval`.
           */
          event RelayerApprovalChanged(address indexed relayer, address indexed sender, bool approved);
          // Internal Balance
          //
          // Users can deposit tokens into the Vault, where they are allocated to their Internal Balance, and later
          // transferred or withdrawn. It can also be used as a source of tokens when joining Pools, as a destination
          // when exiting them, and as either when performing swaps. This usage of Internal Balance results in greatly reduced
          // gas costs when compared to relying on plain ERC20 transfers, leading to large savings for frequent users.
          //
          // Internal Balance management features batching, which means a single contract call can be used to perform multiple
          // operations of different kinds, with different senders and recipients, at once.
          /**
           * @dev Returns `user`'s Internal Balance for a set of tokens.
           */
          function getInternalBalance(address user, IERC20[] memory tokens) external view returns (uint256[] memory);
          /**
           * @dev Performs a set of user balance operations, which involve Internal Balance (deposit, withdraw or transfer)
           * and plain ERC20 transfers using the Vault's allowance. This last feature is particularly useful for relayers, as
           * it lets integrators reuse a user's Vault allowance.
           *
           * For each operation, if the caller is not `sender`, it must be an authorized relayer for them.
           */
          function manageUserBalance(UserBalanceOp[] memory ops) external payable;
          /**
           * @dev Data for `manageUserBalance` operations, which include the possibility for ETH to be sent and received
           without manual WETH wrapping or unwrapping.
           */
          struct UserBalanceOp {
              UserBalanceOpKind kind;
              IAsset asset;
              uint256 amount;
              address sender;
              address payable recipient;
          }
          // There are four possible operations in `manageUserBalance`:
          //
          // - DEPOSIT_INTERNAL
          // Increases the Internal Balance of the `recipient` account by transferring tokens from the corresponding
          // `sender`. The sender must have allowed the Vault to use their tokens via `IERC20.approve()`.
          //
          // ETH can be used by passing the ETH sentinel value as the asset and forwarding ETH in the call: it will be wrapped
          // and deposited as WETH. Any ETH amount remaining will be sent back to the caller (not the sender, which is
          // relevant for relayers).
          //
          // Emits an `InternalBalanceChanged` event.
          //
          //
          // - WITHDRAW_INTERNAL
          // Decreases the Internal Balance of the `sender` account by transferring tokens to the `recipient`.
          //
          // ETH can be used by passing the ETH sentinel value as the asset. This will deduct WETH instead, unwrap it and send
          // it to the recipient as ETH.
          //
          // Emits an `InternalBalanceChanged` event.
          //
          //
          // - TRANSFER_INTERNAL
          // Transfers tokens from the Internal Balance of the `sender` account to the Internal Balance of `recipient`.
          //
          // Reverts if the ETH sentinel value is passed.
          //
          // Emits an `InternalBalanceChanged` event.
          //
          //
          // - TRANSFER_EXTERNAL
          // Transfers tokens from `sender` to `recipient`, using the Vault's ERC20 allowance. This is typically used by
          // relayers, as it lets them reuse a user's Vault allowance.
          //
          // Reverts if the ETH sentinel value is passed.
          //
          // Emits an `ExternalBalanceTransfer` event.
          enum UserBalanceOpKind { DEPOSIT_INTERNAL, WITHDRAW_INTERNAL, TRANSFER_INTERNAL, TRANSFER_EXTERNAL }
          /**
           * @dev Emitted when a user's Internal Balance changes, either from calls to `manageUserBalance`, or through
           * interacting with Pools using Internal Balance.
           *
           * Because Internal Balance works exclusively with ERC20 tokens, ETH deposits and withdrawals will use the WETH
           * address.
           */
          event InternalBalanceChanged(address indexed user, IERC20 indexed token, int256 delta);
          /**
           * @dev Emitted when a user's Vault ERC20 allowance is used by the Vault to transfer tokens to an external account.
           */
          event ExternalBalanceTransfer(IERC20 indexed token, address indexed sender, address recipient, uint256 amount);
          // Pools
          //
          // There are three specialization settings for Pools, which allow for cheaper swaps at the cost of reduced
          // functionality:
          //
          //  - General: no specialization, suited for all Pools. IGeneralPool is used for swap request callbacks, passing the
          // balance of all tokens in the Pool. These Pools have the largest swap costs (because of the extra storage reads),
          // which increase with the number of registered tokens.
          //
          //  - Minimal Swap Info: IMinimalSwapInfoPool is used instead of IGeneralPool, which saves gas by only passing the
          // balance of the two tokens involved in the swap. This is suitable for some pricing algorithms, like the weighted
          // constant product one popularized by Balancer V1. Swap costs are smaller compared to general Pools, and are
          // independent of the number of registered tokens.
          //
          //  - Two Token: only allows two tokens to be registered. This achieves the lowest possible swap gas cost. Like
          // minimal swap info Pools, these are called via IMinimalSwapInfoPool.
          enum PoolSpecialization { GENERAL, MINIMAL_SWAP_INFO, TWO_TOKEN }
          /**
           * @dev Registers the caller account as a Pool with a given specialization setting. Returns the Pool's ID, which
           * is used in all Pool-related functions. Pools cannot be deregistered, nor can the Pool's specialization be
           * changed.
           *
           * The caller is expected to be a smart contract that implements either `IGeneralPool` or `IMinimalSwapInfoPool`,
           * depending on the chosen specialization setting. This contract is known as the Pool's contract.
           *
           * Note that the same contract may register itself as multiple Pools with unique Pool IDs, or in other words,
           * multiple Pools may share the same contract.
           *
           * Emits a `PoolRegistered` event.
           */
          function registerPool(PoolSpecialization specialization) external returns (bytes32);
          /**
           * @dev Emitted when a Pool is registered by calling `registerPool`.
           */
          event PoolRegistered(bytes32 indexed poolId, address indexed poolAddress, PoolSpecialization specialization);
          /**
           * @dev Returns a Pool's contract address and specialization setting.
           */
          function getPool(bytes32 poolId) external view returns (address, PoolSpecialization);
          /**
           * @dev Registers `tokens` for the `poolId` Pool. Must be called by the Pool's contract.
           *
           * Pools can only interact with tokens they have registered. Users join a Pool by transferring registered tokens,
           * exit by receiving registered tokens, and can only swap registered tokens.
           *
           * Each token can only be registered once. For Pools with the Two Token specialization, `tokens` must have a length
           * of two, that is, both tokens must be registered in the same `registerTokens` call, and they must be sorted in
           * ascending order.
           *
           * The `tokens` and `assetManagers` arrays must have the same length, and each entry in these indicates the Asset
           * Manager for the corresponding token. Asset Managers can manage a Pool's tokens via `managePoolBalance`,
           * depositing and withdrawing them directly, and can even set their balance to arbitrary amounts. They are therefore
           * expected to be highly secured smart contracts with sound design principles, and the decision to register an
           * Asset Manager should not be made lightly.
           *
           * Pools can choose not to assign an Asset Manager to a given token by passing in the zero address. Once an Asset
           * Manager is set, it cannot be changed except by deregistering the associated token and registering again with a
           * different Asset Manager.
           *
           * Emits a `TokensRegistered` event.
           */
          function registerTokens(
              bytes32 poolId,
              IERC20[] memory tokens,
              address[] memory assetManagers
          ) external;
          /**
           * @dev Emitted when a Pool registers tokens by calling `registerTokens`.
           */
          event TokensRegistered(bytes32 indexed poolId, IERC20[] tokens, address[] assetManagers);
          /**
           * @dev Deregisters `tokens` for the `poolId` Pool. Must be called by the Pool's contract.
           *
           * Only registered tokens (via `registerTokens`) can be deregistered. Additionally, they must have zero total
           * balance. For Pools with the Two Token specialization, `tokens` must have a length of two, that is, both tokens
           * must be deregistered in the same `deregisterTokens` call.
           *
           * A deregistered token can be re-registered later on, possibly with a different Asset Manager.
           *
           * Emits a `TokensDeregistered` event.
           */
          function deregisterTokens(bytes32 poolId, IERC20[] memory tokens) external;
          /**
           * @dev Emitted when a Pool deregisters tokens by calling `deregisterTokens`.
           */
          event TokensDeregistered(bytes32 indexed poolId, IERC20[] tokens);
          /**
           * @dev Returns detailed information for a Pool's registered token.
           *
           * `cash` is the number of tokens the Vault currently holds for the Pool. `managed` is the number of tokens
           * withdrawn and held outside the Vault by the Pool's token Asset Manager. The Pool's total balance for `token`
           * equals the sum of `cash` and `managed`.
           *
           * Internally, `cash` and `managed` are stored using 112 bits. No action can ever cause a Pool's token `cash`,
           * `managed` or `total` balance to be greater than 2^112 - 1.
           *
           * `lastChangeBlock` is the number of the block in which `token`'s total balance was last modified (via either a
           * join, exit, swap, or Asset Manager update). This value is useful to avoid so-called 'sandwich attacks', for
           * example when developing price oracles. A change of zero (e.g. caused by a swap with amount zero) is considered a
           * change for this purpose, and will update `lastChangeBlock`.
           *
           * `assetManager` is the Pool's token Asset Manager.
           */
          function getPoolTokenInfo(bytes32 poolId, IERC20 token)
              external
              view
              returns (
                  uint256 cash,
                  uint256 managed,
                  uint256 lastChangeBlock,
                  address assetManager
              );
          /**
           * @dev Returns a Pool's registered tokens, the total balance for each, and the latest block when *any* of
           * the tokens' `balances` changed.
           *
           * The order of the `tokens` array is the same order that will be used in `joinPool`, `exitPool`, as well as in all
           * Pool hooks (where applicable). Calls to `registerTokens` and `deregisterTokens` may change this order.
           *
           * If a Pool only registers tokens once, and these are sorted in ascending order, they will be stored in the same
           * order as passed to `registerTokens`.
           *
           * Total balances include both tokens held by the Vault and those withdrawn by the Pool's Asset Managers. These are
           * the amounts used by joins, exits and swaps. For a detailed breakdown of token balances, use `getPoolTokenInfo`
           * instead.
           */
          function getPoolTokens(bytes32 poolId)
              external
              view
              returns (
                  IERC20[] memory tokens,
                  uint256[] memory balances,
                  uint256 lastChangeBlock
              );
          /**
           * @dev Called by users to join a Pool, which transfers tokens from `sender` into the Pool's balance. This will
           * trigger custom Pool behavior, which will typically grant something in return to `recipient` - often tokenized
           * Pool shares.
           *
           * If the caller is not `sender`, it must be an authorized relayer for them.
           *
           * The `assets` and `maxAmountsIn` arrays must have the same length, and each entry indicates the maximum amount
           * to send for each asset. The amounts to send are decided by the Pool and not the Vault: it just enforces
           * these maximums.
           *
           * If joining a Pool that holds WETH, it is possible to send ETH directly: the Vault will do the wrapping. To enable
           * this mechanism, the IAsset sentinel value (the zero address) must be passed in the `assets` array instead of the
           * WETH address. Note that it is not possible to combine ETH and WETH in the same join. Any excess ETH will be sent
           * back to the caller (not the sender, which is important for relayers).
           *
           * `assets` must have the same length and order as the array returned by `getPoolTokens`. This prevents issues when
           * interacting with Pools that register and deregister tokens frequently. If sending ETH however, the array must be
           * sorted *before* replacing the WETH address with the ETH sentinel value (the zero address), which means the final
           * `assets` array might not be sorted. Pools with no registered tokens cannot be joined.
           *
           * If `fromInternalBalance` is true, the caller's Internal Balance will be preferred: ERC20 transfers will only
           * be made for the difference between the requested amount and Internal Balance (if any). Note that ETH cannot be
           * withdrawn from Internal Balance: attempting to do so will trigger a revert.
           *
           * This causes the Vault to call the `IBasePool.onJoinPool` hook on the Pool's contract, where Pools implement
           * their own custom logic. This typically requires additional information from the user (such as the expected number
           * of Pool shares). This can be encoded in the `userData` argument, which is ignored by the Vault and passed
           * directly to the Pool's contract, as is `recipient`.
           *
           * Emits a `PoolBalanceChanged` event.
           */
          function joinPool(
              bytes32 poolId,
              address sender,
              address recipient,
              JoinPoolRequest memory request
          ) external payable;
          struct JoinPoolRequest {
              IAsset[] assets;
              uint256[] maxAmountsIn;
              bytes userData;
              bool fromInternalBalance;
          }
          /**
           * @dev Called by users to exit a Pool, which transfers tokens from the Pool's balance to `recipient`. This will
           * trigger custom Pool behavior, which will typically ask for something in return from `sender` - often tokenized
           * Pool shares. The amount of tokens that can be withdrawn is limited by the Pool's `cash` balance (see
           * `getPoolTokenInfo`).
           *
           * If the caller is not `sender`, it must be an authorized relayer for them.
           *
           * The `tokens` and `minAmountsOut` arrays must have the same length, and each entry in these indicates the minimum
           * token amount to receive for each token contract. The amounts to send are decided by the Pool and not the Vault:
           * it just enforces these minimums.
           *
           * If exiting a Pool that holds WETH, it is possible to receive ETH directly: the Vault will do the unwrapping. To
           * enable this mechanism, the IAsset sentinel value (the zero address) must be passed in the `assets` array instead
           * of the WETH address. Note that it is not possible to combine ETH and WETH in the same exit.
           *
           * `assets` must have the same length and order as the array returned by `getPoolTokens`. This prevents issues when
           * interacting with Pools that register and deregister tokens frequently. If receiving ETH however, the array must
           * be sorted *before* replacing the WETH address with the ETH sentinel value (the zero address), which means the
           * final `assets` array might not be sorted. Pools with no registered tokens cannot be exited.
           *
           * If `toInternalBalance` is true, the tokens will be deposited to `recipient`'s Internal Balance. Otherwise,
           * an ERC20 transfer will be performed. Note that ETH cannot be deposited to Internal Balance: attempting to
           * do so will trigger a revert.
           *
           * `minAmountsOut` is the minimum amount of tokens the user expects to get out of the Pool, for each token in the
           * `tokens` array. This array must match the Pool's registered tokens.
           *
           * This causes the Vault to call the `IBasePool.onExitPool` hook on the Pool's contract, where Pools implement
           * their own custom logic. This typically requires additional information from the user (such as the expected number
           * of Pool shares to return). This can be encoded in the `userData` argument, which is ignored by the Vault and
           * passed directly to the Pool's contract.
           *
           * Emits a `PoolBalanceChanged` event.
           */
          function exitPool(
              bytes32 poolId,
              address sender,
              address payable recipient,
              ExitPoolRequest memory request
          ) external;
          struct ExitPoolRequest {
              IAsset[] assets;
              uint256[] minAmountsOut;
              bytes userData;
              bool toInternalBalance;
          }
          /**
           * @dev Emitted when a user joins or exits a Pool by calling `joinPool` or `exitPool`, respectively.
           */
          event PoolBalanceChanged(
              bytes32 indexed poolId,
              address indexed liquidityProvider,
              IERC20[] tokens,
              int256[] deltas,
              uint256[] protocolFeeAmounts
          );
          enum PoolBalanceChangeKind { JOIN, EXIT }
          // Swaps
          //
          // Users can swap tokens with Pools by calling the `swap` and `batchSwap` functions. To do this,
          // they need not trust Pool contracts in any way: all security checks are made by the Vault. They must however be
          // aware of the Pools' pricing algorithms in order to estimate the prices Pools will quote.
          //
          // The `swap` function executes a single swap, while `batchSwap` can perform multiple swaps in sequence.
          // In each individual swap, tokens of one kind are sent from the sender to the Pool (this is the 'token in'),
          // and tokens of another kind are sent from the Pool to the recipient in exchange (this is the 'token out').
          // More complex swaps, such as one token in to multiple tokens out can be achieved by batching together
          // individual swaps.
          //
          // There are two swap kinds:
          //  - 'given in' swaps, where the amount of tokens in (sent to the Pool) is known, and the Pool determines (via the
          // `onSwap` hook) the amount of tokens out (to send to the recipient).
          //  - 'given out' swaps, where the amount of tokens out (received from the Pool) is known, and the Pool determines
          // (via the `onSwap` hook) the amount of tokens in (to receive from the sender).
          //
          // Additionally, it is possible to chain swaps using a placeholder input amount, which the Vault replaces with
          // the calculated output of the previous swap. If the previous swap was 'given in', this will be the calculated
          // tokenOut amount. If the previous swap was 'given out', it will use the calculated tokenIn amount. These extended
          // swaps are known as 'multihop' swaps, since they 'hop' through a number of intermediate tokens before arriving at
          // the final intended token.
          //
          // In all cases, tokens are only transferred in and out of the Vault (or withdrawn from and deposited into Internal
          // Balance) after all individual swaps have been completed, and the net token balance change computed. This makes
          // certain swap patterns, such as multihops, or swaps that interact with the same token pair in multiple Pools, cost
          // much less gas than they would otherwise.
          //
          // It also means that under certain conditions it is possible to perform arbitrage by swapping with multiple
          // Pools in a way that results in net token movement out of the Vault (profit), with no tokens being sent in (only
          // updating the Pool's internal accounting).
          //
          // To protect users from front-running or the market changing rapidly, they supply a list of 'limits' for each token
          // involved in the swap, where either the maximum number of tokens to send (by passing a positive value) or the
          // minimum amount of tokens to receive (by passing a negative value) is specified.
          //
          // Additionally, a 'deadline' timestamp can also be provided, forcing the swap to fail if it occurs after
          // this point in time (e.g. if the transaction failed to be included in a block promptly).
          //
          // If interacting with Pools that hold WETH, it is possible to both send and receive ETH directly: the Vault will do
          // the wrapping and unwrapping. To enable this mechanism, the IAsset sentinel value (the zero address) must be
          // passed in the `assets` array instead of the WETH address. Note that it is possible to combine ETH and WETH in the
          // same swap. Any excess ETH will be sent back to the caller (not the sender, which is relevant for relayers).
          //
          // Finally, Internal Balance can be used when either sending or receiving tokens.
          enum SwapKind { GIVEN_IN, GIVEN_OUT }
          /**
           * @dev Performs a swap with a single Pool.
           *
           * If the swap is 'given in' (the number of tokens to send to the Pool is known), it returns the amount of tokens
           * taken from the Pool, which must be greater than or equal to `limit`.
           *
           * If the swap is 'given out' (the number of tokens to take from the Pool is known), it returns the amount of tokens
           * sent to the Pool, which must be less than or equal to `limit`.
           *
           * Internal Balance usage and the recipient are determined by the `funds` struct.
           *
           * Emits a `Swap` event.
           */
          function swap(
              SingleSwap memory singleSwap,
              FundManagement memory funds,
              uint256 limit,
              uint256 deadline
          ) external payable returns (uint256);
          /**
           * @dev Data for a single swap executed by `swap`. `amount` is either `amountIn` or `amountOut` depending on
           * the `kind` value.
           *
           * `assetIn` and `assetOut` are either token addresses, or the IAsset sentinel value for ETH (the zero address).
           * Note that Pools never interact with ETH directly: it will be wrapped to or unwrapped from WETH by the Vault.
           *
           * The `userData` field is ignored by the Vault, but forwarded to the Pool in the `onSwap` hook, and may be
           * used to extend swap behavior.
           */
          struct SingleSwap {
              bytes32 poolId;
              SwapKind kind;
              IAsset assetIn;
              IAsset assetOut;
              uint256 amount;
              bytes userData;
          }
          /**
           * @dev Performs a series of swaps with one or multiple Pools. In each individual swap, the caller determines either
           * the amount of tokens sent to or received from the Pool, depending on the `kind` value.
           *
           * Returns an array with the net Vault asset balance deltas. Positive amounts represent tokens (or ETH) sent to the
           * Vault, and negative amounts represent tokens (or ETH) sent by the Vault. Each delta corresponds to the asset at
           * the same index in the `assets` array.
           *
           * Swaps are executed sequentially, in the order specified by the `swaps` array. Each array element describes a
           * Pool, the token to be sent to this Pool, the token to receive from it, and an amount that is either `amountIn` or
           * `amountOut` depending on the swap kind.
           *
           * Multihop swaps can be executed by passing an `amount` value of zero for a swap. This will cause the amount in/out
           * of the previous swap to be used as the amount in for the current one. In a 'given in' swap, 'tokenIn' must equal
           * the previous swap's `tokenOut`. For a 'given out' swap, `tokenOut` must equal the previous swap's `tokenIn`.
           *
           * The `assets` array contains the addresses of all assets involved in the swaps. These are either token addresses,
           * or the IAsset sentinel value for ETH (the zero address). Each entry in the `swaps` array specifies tokens in and
           * out by referencing an index in `assets`. Note that Pools never interact with ETH directly: it will be wrapped to
           * or unwrapped from WETH by the Vault.
           *
           * Internal Balance usage, sender, and recipient are determined by the `funds` struct. The `limits` array specifies
           * the minimum or maximum amount of each token the vault is allowed to transfer.
           *
           * `batchSwap` can be used to make a single swap, like `swap` does, but doing so requires more gas than the
           * equivalent `swap` call.
           *
           * Emits `Swap` events.
           */
          function batchSwap(
              SwapKind kind,
              BatchSwapStep[] memory swaps,
              IAsset[] memory assets,
              FundManagement memory funds,
              int256[] memory limits,
              uint256 deadline
          ) external payable returns (int256[] memory);
          /**
           * @dev Data for each individual swap executed by `batchSwap`. The asset in and out fields are indexes into the
           * `assets` array passed to that function, and ETH assets are converted to WETH.
           *
           * If `amount` is zero, the multihop mechanism is used to determine the actual amount based on the amount in/out
           * from the previous swap, depending on the swap kind.
           *
           * The `userData` field is ignored by the Vault, but forwarded to the Pool in the `onSwap` hook, and may be
           * used to extend swap behavior.
           */
          struct BatchSwapStep {
              bytes32 poolId;
              uint256 assetInIndex;
              uint256 assetOutIndex;
              uint256 amount;
              bytes userData;
          }
          /**
           * @dev Emitted for each individual swap performed by `swap` or `batchSwap`.
           */
          event Swap(
              bytes32 indexed poolId,
              IERC20 indexed tokenIn,
              IERC20 indexed tokenOut,
              uint256 amountIn,
              uint256 amountOut
          );
          /**
           * @dev All tokens in a swap are either sent from the `sender` account to the Vault, or from the Vault to the
           * `recipient` account.
           *
           * If the caller is not `sender`, it must be an authorized relayer for them.
           *
           * If `fromInternalBalance` is true, the `sender`'s Internal Balance will be preferred, performing an ERC20
           * transfer for the difference between the requested amount and the User's Internal Balance (if any). The `sender`
           * must have allowed the Vault to use their tokens via `IERC20.approve()`. This matches the behavior of
           * `joinPool`.
           *
           * If `toInternalBalance` is true, tokens will be deposited to `recipient`'s internal balance instead of
           * transferred. This matches the behavior of `exitPool`.
           *
           * Note that ETH cannot be deposited to or withdrawn from Internal Balance: attempting to do so will trigger a
           * revert.
           */
          struct FundManagement {
              address sender;
              bool fromInternalBalance;
              address payable recipient;
              bool toInternalBalance;
          }
          /**
           * @dev Simulates a call to `batchSwap`, returning an array of Vault asset deltas. Calls to `swap` cannot be
           * simulated directly, but an equivalent `batchSwap` call can and will yield the exact same result.
           *
           * Each element in the array corresponds to the asset at the same index, and indicates the number of tokens (or ETH)
           * the Vault would take from the sender (if positive) or send to the recipient (if negative). The arguments it
           * receives are the same that an equivalent `batchSwap` call would receive.
           *
           * Unlike `batchSwap`, this function performs no checks on the sender or recipient field in the `funds` struct.
           * This makes it suitable to be called by off-chain applications via eth_call without needing to hold tokens,
           * approve them for the Vault, or even know a user's address.
           *
           * Note that this function is not 'view' (due to implementation details): the client code must explicitly execute
           * eth_call instead of eth_sendTransaction.
           */
          function queryBatchSwap(
              SwapKind kind,
              BatchSwapStep[] memory swaps,
              IAsset[] memory assets,
              FundManagement memory funds
          ) external returns (int256[] memory assetDeltas);
          // Flash Loans
          /**
           * @dev Performs a 'flash loan', sending tokens to `recipient`, executing the `receiveFlashLoan` hook on it,
           * and then reverting unless the tokens plus a proportional protocol fee have been returned.
           *
           * The `tokens` and `amounts` arrays must have the same length, and each entry in these indicates the loan amount
           * for each token contract. `tokens` must be sorted in ascending order.
           *
           * The 'userData' field is ignored by the Vault, and forwarded as-is to `recipient` as part of the
           * `receiveFlashLoan` call.
           *
           * Emits `FlashLoan` events.
           */
          function flashLoan(
              IFlashLoanRecipient recipient,
              IERC20[] memory tokens,
              uint256[] memory amounts,
              bytes memory userData
          ) external;
          /**
           * @dev Emitted for each individual flash loan performed by `flashLoan`.
           */
          event FlashLoan(IFlashLoanRecipient indexed recipient, IERC20 indexed token, uint256 amount, uint256 feeAmount);
          // Asset Management
          //
          // Each token registered for a Pool can be assigned an Asset Manager, which is able to freely withdraw the Pool's
          // tokens from the Vault, deposit them, or assign arbitrary values to its `managed` balance (see
          // `getPoolTokenInfo`). This makes them extremely powerful and dangerous. Even if an Asset Manager only directly
          // controls one of the tokens in a Pool, a malicious manager could set that token's balance to manipulate the
          // prices of the other tokens, and then drain the Pool with swaps. The risk of using Asset Managers is therefore
          // not constrained to the tokens they are managing, but extends to the entire Pool's holdings.
          //
          // However, a properly designed Asset Manager smart contract can be safely used for the Pool's benefit,
          // for example by lending unused tokens out for interest, or using them to participate in voting protocols.
          //
          // This concept is unrelated to the IAsset interface.
          /**
           * @dev Performs a set of Pool balance operations, which may be either withdrawals, deposits or updates.
           *
           * Pool Balance management features batching, which means a single contract call can be used to perform multiple
           * operations of different kinds, with different Pools and tokens, at once.
           *
           * For each operation, the caller must be registered as the Asset Manager for `token` in `poolId`.
           */
          function managePoolBalance(PoolBalanceOp[] memory ops) external;
          struct PoolBalanceOp {
              PoolBalanceOpKind kind;
              bytes32 poolId;
              IERC20 token;
              uint256 amount;
          }
          /**
           * Withdrawals decrease the Pool's cash, but increase its managed balance, leaving the total balance unchanged.
           *
           * Deposits increase the Pool's cash, but decrease its managed balance, leaving the total balance unchanged.
           *
           * Updates don't affect the Pool's cash balance, but because the managed balance changes, it does alter the total.
           * The external amount can be either increased or decreased by this call (i.e., reporting a gain or a loss).
           */
          enum PoolBalanceOpKind { WITHDRAW, DEPOSIT, UPDATE }
          /**
           * @dev Emitted when a Pool's token Asset Manager alters its balance via `managePoolBalance`.
           */
          event PoolBalanceManaged(
              bytes32 indexed poolId,
              address indexed assetManager,
              IERC20 indexed token,
              int256 cashDelta,
              int256 managedDelta
          );
          // Protocol Fees
          //
          // Some operations cause the Vault to collect tokens in the form of protocol fees, which can then be withdrawn by
          // permissioned accounts.
          //
          // There are two kinds of protocol fees:
          //
          //  - flash loan fees: charged on all flash loans, as a percentage of the amounts lent.
          //
          //  - swap fees: a percentage of the fees charged by Pools when performing swaps. For a number of reasons, including
          // swap gas costs and interface simplicity, protocol swap fees are not charged on each individual swap. Rather,
          // Pools are expected to keep track of how much they have charged in swap fees, and pay any outstanding debts to the
          // Vault when they are joined or exited. This prevents users from joining a Pool with unpaid debt, as well as
          // exiting a Pool in debt without first paying their share.
          /**
           * @dev Returns the current protocol fee module.
           */
          function getProtocolFeesCollector() external view returns (ProtocolFeesCollector);
          /**
           * @dev Safety mechanism to pause most Vault operations in the event of an emergency - typically detection of an
           * error in some part of the system.
           *
           * The Vault can only be paused during an initial time period, after which pausing is forever disabled.
           *
           * While the contract is paused, the following features are disabled:
           * - depositing and transferring internal balance
           * - transferring external balance (using the Vault's allowance)
           * - swaps
           * - joining Pools
           * - Asset Manager interactions
           *
           * Internal Balance can still be withdrawn, and Pools exited.
           */
          function setPaused(bool paused) external;
          /**
           * @dev Returns the Vault's WETH instance.
           */
          function WETH() external view returns (IWETH);
          // solhint-disable-previous-line func-name-mixedcase
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      interface IAuthorizer {
          /**
           * @dev Returns true if `account` can perform the action described by `actionId` in the contract `where`.
           */
          function canPerform(
              bytes32 actionId,
              address account,
              address where
          ) external view returns (bool);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      // solhint-disable
      /**
       * @dev Reverts if `condition` is false, with a revert reason containing `errorCode`. Only codes up to 999 are
       * supported.
       */
      function _require(bool condition, uint256 errorCode) pure {
          if (!condition) _revert(errorCode);
      }
      /**
       * @dev Reverts with a revert reason containing `errorCode`. Only codes up to 999 are supported.
       */
      function _revert(uint256 errorCode) pure {
          // We're going to dynamically create a revert string based on the error code, with the following format:
          // 'BAL#{errorCode}'
          // where the code is left-padded with zeroes to three digits (so they range from 000 to 999).
          //
          // We don't have revert strings embedded in the contract to save bytecode size: it takes much less space to store a
          // number (8 to 16 bits) than the individual string characters.
          //
          // The dynamic string creation algorithm that follows could be implemented in Solidity, but assembly allows for a
          // much denser implementation, again saving bytecode size. Given this function unconditionally reverts, this is a
          // safe place to rely on it without worrying about how its usage might affect e.g. memory contents.
          assembly {
              // First, we need to compute the ASCII representation of the error code. We assume that it is in the 0-999
              // range, so we only need to convert three digits. To convert the digits to ASCII, we add 0x30, the value for
              // the '0' character.
              let units := add(mod(errorCode, 10), 0x30)
              errorCode := div(errorCode, 10)
              let tenths := add(mod(errorCode, 10), 0x30)
              errorCode := div(errorCode, 10)
              let hundreds := add(mod(errorCode, 10), 0x30)
              // With the individual characters, we can now construct the full string. The "BAL#" part is a known constant
              // (0x42414c23): we simply shift this by 24 (to provide space for the 3 bytes of the error code), and add the
              // characters to it, each shifted by a multiple of 8.
              // The revert reason is then shifted left by 200 bits (256 minus the length of the string, 7 characters * 8 bits
              // per character = 56) to locate it in the most significant part of the 256 slot (the beginning of a byte
              // array).
              let revertReason := shl(200, add(0x42414c23000000, add(add(units, shl(8, tenths)), shl(16, hundreds))))
              // We can now encode the reason in memory, which can be safely overwritten as we're about to revert. The encoded
              // message will have the following layout:
              // [ revert reason identifier ] [ string location offset ] [ string length ] [ string contents ]
              // The Solidity revert reason identifier is 0x08c739a0, the function selector of the Error(string) function. We
              // also write zeroes to the next 28 bytes of memory, but those are about to be overwritten.
              mstore(0x0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
              // Next is the offset to the location of the string, which will be placed immediately after (20 bytes away).
              mstore(0x04, 0x0000000000000000000000000000000000000000000000000000000000000020)
              // The string length is fixed: 7 characters.
              mstore(0x24, 7)
              // Finally, the string itself is stored.
              mstore(0x44, revertReason)
              // Even if the string is only 7 bytes long, we need to return a full 32 byte slot containing it. The length of
              // the encoded message is therefore 4 + 32 + 32 + 32 = 100.
              revert(0, 100)
          }
      }
      library Errors {
          // Math
          uint256 internal constant ADD_OVERFLOW = 0;
          uint256 internal constant SUB_OVERFLOW = 1;
          uint256 internal constant SUB_UNDERFLOW = 2;
          uint256 internal constant MUL_OVERFLOW = 3;
          uint256 internal constant ZERO_DIVISION = 4;
          uint256 internal constant DIV_INTERNAL = 5;
          uint256 internal constant X_OUT_OF_BOUNDS = 6;
          uint256 internal constant Y_OUT_OF_BOUNDS = 7;
          uint256 internal constant PRODUCT_OUT_OF_BOUNDS = 8;
          uint256 internal constant INVALID_EXPONENT = 9;
          // Input
          uint256 internal constant OUT_OF_BOUNDS = 100;
          uint256 internal constant UNSORTED_ARRAY = 101;
          uint256 internal constant UNSORTED_TOKENS = 102;
          uint256 internal constant INPUT_LENGTH_MISMATCH = 103;
          uint256 internal constant ZERO_TOKEN = 104;
          // Shared pools
          uint256 internal constant MIN_TOKENS = 200;
          uint256 internal constant MAX_TOKENS = 201;
          uint256 internal constant MAX_SWAP_FEE_PERCENTAGE = 202;
          uint256 internal constant MIN_SWAP_FEE_PERCENTAGE = 203;
          uint256 internal constant MINIMUM_BPT = 204;
          uint256 internal constant CALLER_NOT_VAULT = 205;
          uint256 internal constant UNINITIALIZED = 206;
          uint256 internal constant BPT_IN_MAX_AMOUNT = 207;
          uint256 internal constant BPT_OUT_MIN_AMOUNT = 208;
          uint256 internal constant EXPIRED_PERMIT = 209;
          // Pools
          uint256 internal constant MIN_AMP = 300;
          uint256 internal constant MAX_AMP = 301;
          uint256 internal constant MIN_WEIGHT = 302;
          uint256 internal constant MAX_STABLE_TOKENS = 303;
          uint256 internal constant MAX_IN_RATIO = 304;
          uint256 internal constant MAX_OUT_RATIO = 305;
          uint256 internal constant MIN_BPT_IN_FOR_TOKEN_OUT = 306;
          uint256 internal constant MAX_OUT_BPT_FOR_TOKEN_IN = 307;
          uint256 internal constant NORMALIZED_WEIGHT_INVARIANT = 308;
          uint256 internal constant INVALID_TOKEN = 309;
          uint256 internal constant UNHANDLED_JOIN_KIND = 310;
          uint256 internal constant ZERO_INVARIANT = 311;
          uint256 internal constant ORACLE_INVALID_SECONDS_QUERY = 312;
          uint256 internal constant ORACLE_NOT_INITIALIZED = 313;
          uint256 internal constant ORACLE_QUERY_TOO_OLD = 314;
          uint256 internal constant ORACLE_INVALID_INDEX = 315;
          uint256 internal constant ORACLE_BAD_SECS = 316;
          // Lib
          uint256 internal constant REENTRANCY = 400;
          uint256 internal constant SENDER_NOT_ALLOWED = 401;
          uint256 internal constant PAUSED = 402;
          uint256 internal constant PAUSE_WINDOW_EXPIRED = 403;
          uint256 internal constant MAX_PAUSE_WINDOW_DURATION = 404;
          uint256 internal constant MAX_BUFFER_PERIOD_DURATION = 405;
          uint256 internal constant INSUFFICIENT_BALANCE = 406;
          uint256 internal constant INSUFFICIENT_ALLOWANCE = 407;
          uint256 internal constant ERC20_TRANSFER_FROM_ZERO_ADDRESS = 408;
          uint256 internal constant ERC20_TRANSFER_TO_ZERO_ADDRESS = 409;
          uint256 internal constant ERC20_MINT_TO_ZERO_ADDRESS = 410;
          uint256 internal constant ERC20_BURN_FROM_ZERO_ADDRESS = 411;
          uint256 internal constant ERC20_APPROVE_FROM_ZERO_ADDRESS = 412;
          uint256 internal constant ERC20_APPROVE_TO_ZERO_ADDRESS = 413;
          uint256 internal constant ERC20_TRANSFER_EXCEEDS_ALLOWANCE = 414;
          uint256 internal constant ERC20_DECREASED_ALLOWANCE_BELOW_ZERO = 415;
          uint256 internal constant ERC20_TRANSFER_EXCEEDS_BALANCE = 416;
          uint256 internal constant ERC20_BURN_EXCEEDS_ALLOWANCE = 417;
          uint256 internal constant SAFE_ERC20_CALL_FAILED = 418;
          uint256 internal constant ADDRESS_INSUFFICIENT_BALANCE = 419;
          uint256 internal constant ADDRESS_CANNOT_SEND_VALUE = 420;
          uint256 internal constant SAFE_CAST_VALUE_CANT_FIT_INT256 = 421;
          uint256 internal constant GRANT_SENDER_NOT_ADMIN = 422;
          uint256 internal constant REVOKE_SENDER_NOT_ADMIN = 423;
          uint256 internal constant RENOUNCE_SENDER_NOT_ALLOWED = 424;
          uint256 internal constant BUFFER_PERIOD_EXPIRED = 425;
          // Vault
          uint256 internal constant INVALID_POOL_ID = 500;
          uint256 internal constant CALLER_NOT_POOL = 501;
          uint256 internal constant SENDER_NOT_ASSET_MANAGER = 502;
          uint256 internal constant USER_DOESNT_ALLOW_RELAYER = 503;
          uint256 internal constant INVALID_SIGNATURE = 504;
          uint256 internal constant EXIT_BELOW_MIN = 505;
          uint256 internal constant JOIN_ABOVE_MAX = 506;
          uint256 internal constant SWAP_LIMIT = 507;
          uint256 internal constant SWAP_DEADLINE = 508;
          uint256 internal constant CANNOT_SWAP_SAME_TOKEN = 509;
          uint256 internal constant UNKNOWN_AMOUNT_IN_FIRST_SWAP = 510;
          uint256 internal constant MALCONSTRUCTED_MULTIHOP_SWAP = 511;
          uint256 internal constant INTERNAL_BALANCE_OVERFLOW = 512;
          uint256 internal constant INSUFFICIENT_INTERNAL_BALANCE = 513;
          uint256 internal constant INVALID_ETH_INTERNAL_BALANCE = 514;
          uint256 internal constant INVALID_POST_LOAN_BALANCE = 515;
          uint256 internal constant INSUFFICIENT_ETH = 516;
          uint256 internal constant UNALLOCATED_ETH = 517;
          uint256 internal constant ETH_TRANSFER = 518;
          uint256 internal constant CANNOT_USE_ETH_SENTINEL = 519;
          uint256 internal constant TOKENS_MISMATCH = 520;
          uint256 internal constant TOKEN_NOT_REGISTERED = 521;
          uint256 internal constant TOKEN_ALREADY_REGISTERED = 522;
          uint256 internal constant TOKENS_ALREADY_SET = 523;
          uint256 internal constant TOKENS_LENGTH_MUST_BE_2 = 524;
          uint256 internal constant NONZERO_TOKEN_BALANCE = 525;
          uint256 internal constant BALANCE_TOTAL_OVERFLOW = 526;
          uint256 internal constant POOL_NO_TOKENS = 527;
          uint256 internal constant INSUFFICIENT_FLASH_LOAN_BALANCE = 528;
          // Fees
          uint256 internal constant SWAP_FEE_PERCENTAGE_TOO_HIGH = 600;
          uint256 internal constant FLASH_LOAN_FEE_PERCENTAGE_TOO_HIGH = 601;
          uint256 internal constant INSUFFICIENT_FLASH_LOAN_FEE_AMOUNT = 602;
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      /**
       * @dev This is an empty interface used to represent either ERC20-conforming token contracts or ETH (using the zero
       * address sentinel value). We're just relying on the fact that `interface` can be used to declare new address-like
       * types.
       *
       * This concept is unrelated to a Pool's Asset Managers.
       */
      interface IAsset {
          // solhint-disable-previous-line no-empty-blocks
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      interface IAuthentication {
          /**
           * @dev Returns the action identifier associated with the external function described by `selector`.
           */
          function getActionId(bytes4 selector) external view returns (bytes32);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "../../lib/openzeppelin/IERC20.sol";
      /**
       * @dev Interface for the WETH token contract used internally for wrapping and unwrapping, to support
       * sending and receiving ETH in joins, swaps, and internal balance deposits and withdrawals.
       */
      interface IWETH is IERC20 {
          function deposit() external payable;
          function withdraw(uint256 amount) external;
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      // Inspired by Aave Protocol's IFlashLoanReceiver.
      import "../../lib/openzeppelin/IERC20.sol";
      interface IFlashLoanRecipient {
          /**
           * @dev When `flashLoan` is called on the Vault, it invokes the `receiveFlashLoan` hook on the recipient.
           *
           * At the time of the call, the Vault will have transferred `amounts` for `tokens` to the recipient. Before this
           * call returns, the recipient must have transferred `amounts` plus `feeAmounts` for each token back to the
           * Vault, or else the entire flash loan will revert.
           *
           * `userData` is the same value passed in the `IVault.flashLoan` call.
           */
          function receiveFlashLoan(
              IERC20[] memory tokens,
              uint256[] memory amounts,
              uint256[] memory feeAmounts,
              bytes memory userData
          ) external;
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      /**
       * @dev Interface for the SignatureValidator helper, used to support meta-transactions.
       */
      interface ISignaturesValidator {
          /**
           * @dev Returns the EIP712 domain separator.
           */
          function getDomainSeparator() external view returns (bytes32);
          /**
           * @dev Returns the next nonce used by an address to sign messages.
           */
          function getNextNonce(address user) external view returns (uint256);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      /**
       * @dev Interface for the TemporarilyPausable helper.
       */
      interface ITemporarilyPausable {
          /**
           * @dev Emitted every time the pause state changes by `_setPaused`.
           */
          event PausedStateChanged(bool paused);
          /**
           * @dev Returns the current paused state.
           */
          function getPausedState()
              external
              view
              returns (
                  bool paused,
                  uint256 pauseWindowEndTime,
                  uint256 bufferPeriodEndTime
              );
      }
      

      File 3 of 5: ComposableStablePool
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity >=0.7.0 <0.9.0;
      /**
       * @notice Simple interface to retrieve the version of a deployed contract.
       */
      interface IVersion {
          /**
           * @dev Returns a JSON representation of the contract version containing name, version number and task ID.
           */
          function version() external view returns (string memory);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma experimental ABIEncoderV2;
      import "../solidity-utils/openzeppelin/IERC20.sol";
      import "../solidity-utils/helpers/IAuthentication.sol";
      import "../solidity-utils/helpers/ISignaturesValidator.sol";
      import "../solidity-utils/helpers/ITemporarilyPausable.sol";
      import "../solidity-utils/misc/IWETH.sol";
      import "./IAsset.sol";
      import "./IAuthorizer.sol";
      import "./IFlashLoanRecipient.sol";
      import "./IProtocolFeesCollector.sol";
      pragma solidity ^0.7.0;
      /**
       * @dev Full external interface for the Vault core contract - no external or public methods exist in the contract that
       * don't override one of these declarations.
       */
      interface IVault is ISignaturesValidator, ITemporarilyPausable, IAuthentication {
          // Generalities about the Vault:
          //
          // - Whenever documentation refers to 'tokens', it strictly refers to ERC20-compliant token contracts. Tokens are
          // transferred out of the Vault by calling the `IERC20.transfer` function, and transferred in by calling
          // `IERC20.transferFrom`. In these cases, the sender must have previously allowed the Vault to use their tokens by
          // calling `IERC20.approve`. The only deviation from the ERC20 standard that is supported is functions not returning
          // a boolean value: in these scenarios, a non-reverting call is assumed to be successful.
          //
          // - All non-view functions in the Vault are non-reentrant: calling them while another one is mid-execution (e.g.
          // while execution control is transferred to a token contract during a swap) will result in a revert. View
          // functions can be called in a re-reentrant way, but doing so might cause them to return inconsistent results.
          // Contracts calling view functions in the Vault must make sure the Vault has not already been entered.
          //
          // - View functions revert if referring to either unregistered Pools, or unregistered tokens for registered Pools.
          // Authorizer
          //
          // Some system actions are permissioned, like setting and collecting protocol fees. This permissioning system exists
          // outside of the Vault in the Authorizer contract: the Vault simply calls the Authorizer to check if the caller
          // can perform a given action.
          /**
           * @dev Returns the Vault's Authorizer.
           */
          function getAuthorizer() external view returns (IAuthorizer);
          /**
           * @dev Sets a new Authorizer for the Vault. The caller must be allowed by the current Authorizer to do this.
           *
           * Emits an `AuthorizerChanged` event.
           */
          function setAuthorizer(IAuthorizer newAuthorizer) external;
          /**
           * @dev Emitted when a new authorizer is set by `setAuthorizer`.
           */
          event AuthorizerChanged(IAuthorizer indexed newAuthorizer);
          // Relayers
          //
          // Additionally, it is possible for an account to perform certain actions on behalf of another one, using their
          // Vault ERC20 allowance and Internal Balance. These accounts are said to be 'relayers' for these Vault functions,
          // and are expected to be smart contracts with sound authentication mechanisms. For an account to be able to wield
          // this power, two things must occur:
          //  - The Authorizer must grant the account the permission to be a relayer for the relevant Vault function. This
          //    means that Balancer governance must approve each individual contract to act as a relayer for the intended
          //    functions.
          //  - Each user must approve the relayer to act on their behalf.
          // This double protection means users cannot be tricked into approving malicious relayers (because they will not
          // have been allowed by the Authorizer via governance), nor can malicious relayers approved by a compromised
          // Authorizer or governance drain user funds, since they would also need to be approved by each individual user.
          /**
           * @dev Returns true if `user` has approved `relayer` to act as a relayer for them.
           */
          function hasApprovedRelayer(address user, address relayer) external view returns (bool);
          /**
           * @dev Allows `relayer` to act as a relayer for `sender` if `approved` is true, and disallows it otherwise.
           *
           * Emits a `RelayerApprovalChanged` event.
           */
          function setRelayerApproval(
              address sender,
              address relayer,
              bool approved
          ) external;
          /**
           * @dev Emitted every time a relayer is approved or disapproved by `setRelayerApproval`.
           */
          event RelayerApprovalChanged(address indexed relayer, address indexed sender, bool approved);
          // Internal Balance
          //
          // Users can deposit tokens into the Vault, where they are allocated to their Internal Balance, and later
          // transferred or withdrawn. It can also be used as a source of tokens when joining Pools, as a destination
          // when exiting them, and as either when performing swaps. This usage of Internal Balance results in greatly reduced
          // gas costs when compared to relying on plain ERC20 transfers, leading to large savings for frequent users.
          //
          // Internal Balance management features batching, which means a single contract call can be used to perform multiple
          // operations of different kinds, with different senders and recipients, at once.
          /**
           * @dev Returns `user`'s Internal Balance for a set of tokens.
           */
          function getInternalBalance(address user, IERC20[] memory tokens) external view returns (uint256[] memory);
          /**
           * @dev Performs a set of user balance operations, which involve Internal Balance (deposit, withdraw or transfer)
           * and plain ERC20 transfers using the Vault's allowance. This last feature is particularly useful for relayers, as
           * it lets integrators reuse a user's Vault allowance.
           *
           * For each operation, if the caller is not `sender`, it must be an authorized relayer for them.
           */
          function manageUserBalance(UserBalanceOp[] memory ops) external payable;
          /**
           * @dev Data for `manageUserBalance` operations, which include the possibility for ETH to be sent and received
           without manual WETH wrapping or unwrapping.
           */
          struct UserBalanceOp {
              UserBalanceOpKind kind;
              IAsset asset;
              uint256 amount;
              address sender;
              address payable recipient;
          }
          // There are four possible operations in `manageUserBalance`:
          //
          // - DEPOSIT_INTERNAL
          // Increases the Internal Balance of the `recipient` account by transferring tokens from the corresponding
          // `sender`. The sender must have allowed the Vault to use their tokens via `IERC20.approve()`.
          //
          // ETH can be used by passing the ETH sentinel value as the asset and forwarding ETH in the call: it will be wrapped
          // and deposited as WETH. Any ETH amount remaining will be sent back to the caller (not the sender, which is
          // relevant for relayers).
          //
          // Emits an `InternalBalanceChanged` event.
          //
          //
          // - WITHDRAW_INTERNAL
          // Decreases the Internal Balance of the `sender` account by transferring tokens to the `recipient`.
          //
          // ETH can be used by passing the ETH sentinel value as the asset. This will deduct WETH instead, unwrap it and send
          // it to the recipient as ETH.
          //
          // Emits an `InternalBalanceChanged` event.
          //
          //
          // - TRANSFER_INTERNAL
          // Transfers tokens from the Internal Balance of the `sender` account to the Internal Balance of `recipient`.
          //
          // Reverts if the ETH sentinel value is passed.
          //
          // Emits an `InternalBalanceChanged` event.
          //
          //
          // - TRANSFER_EXTERNAL
          // Transfers tokens from `sender` to `recipient`, using the Vault's ERC20 allowance. This is typically used by
          // relayers, as it lets them reuse a user's Vault allowance.
          //
          // Reverts if the ETH sentinel value is passed.
          //
          // Emits an `ExternalBalanceTransfer` event.
          enum UserBalanceOpKind { DEPOSIT_INTERNAL, WITHDRAW_INTERNAL, TRANSFER_INTERNAL, TRANSFER_EXTERNAL }
          /**
           * @dev Emitted when a user's Internal Balance changes, either from calls to `manageUserBalance`, or through
           * interacting with Pools using Internal Balance.
           *
           * Because Internal Balance works exclusively with ERC20 tokens, ETH deposits and withdrawals will use the WETH
           * address.
           */
          event InternalBalanceChanged(address indexed user, IERC20 indexed token, int256 delta);
          /**
           * @dev Emitted when a user's Vault ERC20 allowance is used by the Vault to transfer tokens to an external account.
           */
          event ExternalBalanceTransfer(IERC20 indexed token, address indexed sender, address recipient, uint256 amount);
          // Pools
          //
          // There are three specialization settings for Pools, which allow for cheaper swaps at the cost of reduced
          // functionality:
          //
          //  - General: no specialization, suited for all Pools. IGeneralPool is used for swap request callbacks, passing the
          // balance of all tokens in the Pool. These Pools have the largest swap costs (because of the extra storage reads),
          // which increase with the number of registered tokens.
          //
          //  - Minimal Swap Info: IMinimalSwapInfoPool is used instead of IGeneralPool, which saves gas by only passing the
          // balance of the two tokens involved in the swap. This is suitable for some pricing algorithms, like the weighted
          // constant product one popularized by Balancer V1. Swap costs are smaller compared to general Pools, and are
          // independent of the number of registered tokens.
          //
          //  - Two Token: only allows two tokens to be registered. This achieves the lowest possible swap gas cost. Like
          // minimal swap info Pools, these are called via IMinimalSwapInfoPool.
          enum PoolSpecialization { GENERAL, MINIMAL_SWAP_INFO, TWO_TOKEN }
          /**
           * @dev Registers the caller account as a Pool with a given specialization setting. Returns the Pool's ID, which
           * is used in all Pool-related functions. Pools cannot be deregistered, nor can the Pool's specialization be
           * changed.
           *
           * The caller is expected to be a smart contract that implements either `IGeneralPool` or `IMinimalSwapInfoPool`,
           * depending on the chosen specialization setting. This contract is known as the Pool's contract.
           *
           * Note that the same contract may register itself as multiple Pools with unique Pool IDs, or in other words,
           * multiple Pools may share the same contract.
           *
           * Emits a `PoolRegistered` event.
           */
          function registerPool(PoolSpecialization specialization) external returns (bytes32);
          /**
           * @dev Emitted when a Pool is registered by calling `registerPool`.
           */
          event PoolRegistered(bytes32 indexed poolId, address indexed poolAddress, PoolSpecialization specialization);
          /**
           * @dev Returns a Pool's contract address and specialization setting.
           */
          function getPool(bytes32 poolId) external view returns (address, PoolSpecialization);
          /**
           * @dev Registers `tokens` for the `poolId` Pool. Must be called by the Pool's contract.
           *
           * Pools can only interact with tokens they have registered. Users join a Pool by transferring registered tokens,
           * exit by receiving registered tokens, and can only swap registered tokens.
           *
           * Each token can only be registered once. For Pools with the Two Token specialization, `tokens` must have a length
           * of two, that is, both tokens must be registered in the same `registerTokens` call, and they must be sorted in
           * ascending order.
           *
           * The `tokens` and `assetManagers` arrays must have the same length, and each entry in these indicates the Asset
           * Manager for the corresponding token. Asset Managers can manage a Pool's tokens via `managePoolBalance`,
           * depositing and withdrawing them directly, and can even set their balance to arbitrary amounts. They are therefore
           * expected to be highly secured smart contracts with sound design principles, and the decision to register an
           * Asset Manager should not be made lightly.
           *
           * Pools can choose not to assign an Asset Manager to a given token by passing in the zero address. Once an Asset
           * Manager is set, it cannot be changed except by deregistering the associated token and registering again with a
           * different Asset Manager.
           *
           * Emits a `TokensRegistered` event.
           */
          function registerTokens(
              bytes32 poolId,
              IERC20[] memory tokens,
              address[] memory assetManagers
          ) external;
          /**
           * @dev Emitted when a Pool registers tokens by calling `registerTokens`.
           */
          event TokensRegistered(bytes32 indexed poolId, IERC20[] tokens, address[] assetManagers);
          /**
           * @dev Deregisters `tokens` for the `poolId` Pool. Must be called by the Pool's contract.
           *
           * Only registered tokens (via `registerTokens`) can be deregistered. Additionally, they must have zero total
           * balance. For Pools with the Two Token specialization, `tokens` must have a length of two, that is, both tokens
           * must be deregistered in the same `deregisterTokens` call.
           *
           * A deregistered token can be re-registered later on, possibly with a different Asset Manager.
           *
           * Emits a `TokensDeregistered` event.
           */
          function deregisterTokens(bytes32 poolId, IERC20[] memory tokens) external;
          /**
           * @dev Emitted when a Pool deregisters tokens by calling `deregisterTokens`.
           */
          event TokensDeregistered(bytes32 indexed poolId, IERC20[] tokens);
          /**
           * @dev Returns detailed information for a Pool's registered token.
           *
           * `cash` is the number of tokens the Vault currently holds for the Pool. `managed` is the number of tokens
           * withdrawn and held outside the Vault by the Pool's token Asset Manager. The Pool's total balance for `token`
           * equals the sum of `cash` and `managed`.
           *
           * Internally, `cash` and `managed` are stored using 112 bits. No action can ever cause a Pool's token `cash`,
           * `managed` or `total` balance to be greater than 2^112 - 1.
           *
           * `lastChangeBlock` is the number of the block in which `token`'s total balance was last modified (via either a
           * join, exit, swap, or Asset Manager update). This value is useful to avoid so-called 'sandwich attacks', for
           * example when developing price oracles. A change of zero (e.g. caused by a swap with amount zero) is considered a
           * change for this purpose, and will update `lastChangeBlock`.
           *
           * `assetManager` is the Pool's token Asset Manager.
           */
          function getPoolTokenInfo(bytes32 poolId, IERC20 token)
              external
              view
              returns (
                  uint256 cash,
                  uint256 managed,
                  uint256 lastChangeBlock,
                  address assetManager
              );
          /**
           * @dev Returns a Pool's registered tokens, the total balance for each, and the latest block when *any* of
           * the tokens' `balances` changed.
           *
           * The order of the `tokens` array is the same order that will be used in `joinPool`, `exitPool`, as well as in all
           * Pool hooks (where applicable). Calls to `registerTokens` and `deregisterTokens` may change this order.
           *
           * If a Pool only registers tokens once, and these are sorted in ascending order, they will be stored in the same
           * order as passed to `registerTokens`.
           *
           * Total balances include both tokens held by the Vault and those withdrawn by the Pool's Asset Managers. These are
           * the amounts used by joins, exits and swaps. For a detailed breakdown of token balances, use `getPoolTokenInfo`
           * instead.
           */
          function getPoolTokens(bytes32 poolId)
              external
              view
              returns (
                  IERC20[] memory tokens,
                  uint256[] memory balances,
                  uint256 lastChangeBlock
              );
          /**
           * @dev Called by users to join a Pool, which transfers tokens from `sender` into the Pool's balance. This will
           * trigger custom Pool behavior, which will typically grant something in return to `recipient` - often tokenized
           * Pool shares.
           *
           * If the caller is not `sender`, it must be an authorized relayer for them.
           *
           * The `assets` and `maxAmountsIn` arrays must have the same length, and each entry indicates the maximum amount
           * to send for each asset. The amounts to send are decided by the Pool and not the Vault: it just enforces
           * these maximums.
           *
           * If joining a Pool that holds WETH, it is possible to send ETH directly: the Vault will do the wrapping. To enable
           * this mechanism, the IAsset sentinel value (the zero address) must be passed in the `assets` array instead of the
           * WETH address. Note that it is not possible to combine ETH and WETH in the same join. Any excess ETH will be sent
           * back to the caller (not the sender, which is important for relayers).
           *
           * `assets` must have the same length and order as the array returned by `getPoolTokens`. This prevents issues when
           * interacting with Pools that register and deregister tokens frequently. If sending ETH however, the array must be
           * sorted *before* replacing the WETH address with the ETH sentinel value (the zero address), which means the final
           * `assets` array might not be sorted. Pools with no registered tokens cannot be joined.
           *
           * If `fromInternalBalance` is true, the caller's Internal Balance will be preferred: ERC20 transfers will only
           * be made for the difference between the requested amount and Internal Balance (if any). Note that ETH cannot be
           * withdrawn from Internal Balance: attempting to do so will trigger a revert.
           *
           * This causes the Vault to call the `IBasePool.onJoinPool` hook on the Pool's contract, where Pools implement
           * their own custom logic. This typically requires additional information from the user (such as the expected number
           * of Pool shares). This can be encoded in the `userData` argument, which is ignored by the Vault and passed
           * directly to the Pool's contract, as is `recipient`.
           *
           * Emits a `PoolBalanceChanged` event.
           */
          function joinPool(
              bytes32 poolId,
              address sender,
              address recipient,
              JoinPoolRequest memory request
          ) external payable;
          struct JoinPoolRequest {
              IAsset[] assets;
              uint256[] maxAmountsIn;
              bytes userData;
              bool fromInternalBalance;
          }
          /**
           * @dev Called by users to exit a Pool, which transfers tokens from the Pool's balance to `recipient`. This will
           * trigger custom Pool behavior, which will typically ask for something in return from `sender` - often tokenized
           * Pool shares. The amount of tokens that can be withdrawn is limited by the Pool's `cash` balance (see
           * `getPoolTokenInfo`).
           *
           * If the caller is not `sender`, it must be an authorized relayer for them.
           *
           * The `tokens` and `minAmountsOut` arrays must have the same length, and each entry in these indicates the minimum
           * token amount to receive for each token contract. The amounts to send are decided by the Pool and not the Vault:
           * it just enforces these minimums.
           *
           * If exiting a Pool that holds WETH, it is possible to receive ETH directly: the Vault will do the unwrapping. To
           * enable this mechanism, the IAsset sentinel value (the zero address) must be passed in the `assets` array instead
           * of the WETH address. Note that it is not possible to combine ETH and WETH in the same exit.
           *
           * `assets` must have the same length and order as the array returned by `getPoolTokens`. This prevents issues when
           * interacting with Pools that register and deregister tokens frequently. If receiving ETH however, the array must
           * be sorted *before* replacing the WETH address with the ETH sentinel value (the zero address), which means the
           * final `assets` array might not be sorted. Pools with no registered tokens cannot be exited.
           *
           * If `toInternalBalance` is true, the tokens will be deposited to `recipient`'s Internal Balance. Otherwise,
           * an ERC20 transfer will be performed. Note that ETH cannot be deposited to Internal Balance: attempting to
           * do so will trigger a revert.
           *
           * `minAmountsOut` is the minimum amount of tokens the user expects to get out of the Pool, for each token in the
           * `tokens` array. This array must match the Pool's registered tokens.
           *
           * This causes the Vault to call the `IBasePool.onExitPool` hook on the Pool's contract, where Pools implement
           * their own custom logic. This typically requires additional information from the user (such as the expected number
           * of Pool shares to return). This can be encoded in the `userData` argument, which is ignored by the Vault and
           * passed directly to the Pool's contract.
           *
           * Emits a `PoolBalanceChanged` event.
           */
          function exitPool(
              bytes32 poolId,
              address sender,
              address payable recipient,
              ExitPoolRequest memory request
          ) external;
          struct ExitPoolRequest {
              IAsset[] assets;
              uint256[] minAmountsOut;
              bytes userData;
              bool toInternalBalance;
          }
          /**
           * @dev Emitted when a user joins or exits a Pool by calling `joinPool` or `exitPool`, respectively.
           */
          event PoolBalanceChanged(
              bytes32 indexed poolId,
              address indexed liquidityProvider,
              IERC20[] tokens,
              int256[] deltas,
              uint256[] protocolFeeAmounts
          );
          enum PoolBalanceChangeKind { JOIN, EXIT }
          // Swaps
          //
          // Users can swap tokens with Pools by calling the `swap` and `batchSwap` functions. To do this,
          // they need not trust Pool contracts in any way: all security checks are made by the Vault. They must however be
          // aware of the Pools' pricing algorithms in order to estimate the prices Pools will quote.
          //
          // The `swap` function executes a single swap, while `batchSwap` can perform multiple swaps in sequence.
          // In each individual swap, tokens of one kind are sent from the sender to the Pool (this is the 'token in'),
          // and tokens of another kind are sent from the Pool to the recipient in exchange (this is the 'token out').
          // More complex swaps, such as one token in to multiple tokens out can be achieved by batching together
          // individual swaps.
          //
          // There are two swap kinds:
          //  - 'given in' swaps, where the amount of tokens in (sent to the Pool) is known, and the Pool determines (via the
          // `onSwap` hook) the amount of tokens out (to send to the recipient).
          //  - 'given out' swaps, where the amount of tokens out (received from the Pool) is known, and the Pool determines
          // (via the `onSwap` hook) the amount of tokens in (to receive from the sender).
          //
          // Additionally, it is possible to chain swaps using a placeholder input amount, which the Vault replaces with
          // the calculated output of the previous swap. If the previous swap was 'given in', this will be the calculated
          // tokenOut amount. If the previous swap was 'given out', it will use the calculated tokenIn amount. These extended
          // swaps are known as 'multihop' swaps, since they 'hop' through a number of intermediate tokens before arriving at
          // the final intended token.
          //
          // In all cases, tokens are only transferred in and out of the Vault (or withdrawn from and deposited into Internal
          // Balance) after all individual swaps have been completed, and the net token balance change computed. This makes
          // certain swap patterns, such as multihops, or swaps that interact with the same token pair in multiple Pools, cost
          // much less gas than they would otherwise.
          //
          // It also means that under certain conditions it is possible to perform arbitrage by swapping with multiple
          // Pools in a way that results in net token movement out of the Vault (profit), with no tokens being sent in (only
          // updating the Pool's internal accounting).
          //
          // To protect users from front-running or the market changing rapidly, they supply a list of 'limits' for each token
          // involved in the swap, where either the maximum number of tokens to send (by passing a positive value) or the
          // minimum amount of tokens to receive (by passing a negative value) is specified.
          //
          // Additionally, a 'deadline' timestamp can also be provided, forcing the swap to fail if it occurs after
          // this point in time (e.g. if the transaction failed to be included in a block promptly).
          //
          // If interacting with Pools that hold WETH, it is possible to both send and receive ETH directly: the Vault will do
          // the wrapping and unwrapping. To enable this mechanism, the IAsset sentinel value (the zero address) must be
          // passed in the `assets` array instead of the WETH address. Note that it is possible to combine ETH and WETH in the
          // same swap. Any excess ETH will be sent back to the caller (not the sender, which is relevant for relayers).
          //
          // Finally, Internal Balance can be used when either sending or receiving tokens.
          enum SwapKind { GIVEN_IN, GIVEN_OUT }
          /**
           * @dev Performs a swap with a single Pool.
           *
           * If the swap is 'given in' (the number of tokens to send to the Pool is known), it returns the amount of tokens
           * taken from the Pool, which must be greater than or equal to `limit`.
           *
           * If the swap is 'given out' (the number of tokens to take from the Pool is known), it returns the amount of tokens
           * sent to the Pool, which must be less than or equal to `limit`.
           *
           * Internal Balance usage and the recipient are determined by the `funds` struct.
           *
           * Emits a `Swap` event.
           */
          function swap(
              SingleSwap memory singleSwap,
              FundManagement memory funds,
              uint256 limit,
              uint256 deadline
          ) external payable returns (uint256);
          /**
           * @dev Data for a single swap executed by `swap`. `amount` is either `amountIn` or `amountOut` depending on
           * the `kind` value.
           *
           * `assetIn` and `assetOut` are either token addresses, or the IAsset sentinel value for ETH (the zero address).
           * Note that Pools never interact with ETH directly: it will be wrapped to or unwrapped from WETH by the Vault.
           *
           * The `userData` field is ignored by the Vault, but forwarded to the Pool in the `onSwap` hook, and may be
           * used to extend swap behavior.
           */
          struct SingleSwap {
              bytes32 poolId;
              SwapKind kind;
              IAsset assetIn;
              IAsset assetOut;
              uint256 amount;
              bytes userData;
          }
          /**
           * @dev Performs a series of swaps with one or multiple Pools. In each individual swap, the caller determines either
           * the amount of tokens sent to or received from the Pool, depending on the `kind` value.
           *
           * Returns an array with the net Vault asset balance deltas. Positive amounts represent tokens (or ETH) sent to the
           * Vault, and negative amounts represent tokens (or ETH) sent by the Vault. Each delta corresponds to the asset at
           * the same index in the `assets` array.
           *
           * Swaps are executed sequentially, in the order specified by the `swaps` array. Each array element describes a
           * Pool, the token to be sent to this Pool, the token to receive from it, and an amount that is either `amountIn` or
           * `amountOut` depending on the swap kind.
           *
           * Multihop swaps can be executed by passing an `amount` value of zero for a swap. This will cause the amount in/out
           * of the previous swap to be used as the amount in for the current one. In a 'given in' swap, 'tokenIn' must equal
           * the previous swap's `tokenOut`. For a 'given out' swap, `tokenOut` must equal the previous swap's `tokenIn`.
           *
           * The `assets` array contains the addresses of all assets involved in the swaps. These are either token addresses,
           * or the IAsset sentinel value for ETH (the zero address). Each entry in the `swaps` array specifies tokens in and
           * out by referencing an index in `assets`. Note that Pools never interact with ETH directly: it will be wrapped to
           * or unwrapped from WETH by the Vault.
           *
           * Internal Balance usage, sender, and recipient are determined by the `funds` struct. The `limits` array specifies
           * the minimum or maximum amount of each token the vault is allowed to transfer.
           *
           * `batchSwap` can be used to make a single swap, like `swap` does, but doing so requires more gas than the
           * equivalent `swap` call.
           *
           * Emits `Swap` events.
           */
          function batchSwap(
              SwapKind kind,
              BatchSwapStep[] memory swaps,
              IAsset[] memory assets,
              FundManagement memory funds,
              int256[] memory limits,
              uint256 deadline
          ) external payable returns (int256[] memory);
          /**
           * @dev Data for each individual swap executed by `batchSwap`. The asset in and out fields are indexes into the
           * `assets` array passed to that function, and ETH assets are converted to WETH.
           *
           * If `amount` is zero, the multihop mechanism is used to determine the actual amount based on the amount in/out
           * from the previous swap, depending on the swap kind.
           *
           * The `userData` field is ignored by the Vault, but forwarded to the Pool in the `onSwap` hook, and may be
           * used to extend swap behavior.
           */
          struct BatchSwapStep {
              bytes32 poolId;
              uint256 assetInIndex;
              uint256 assetOutIndex;
              uint256 amount;
              bytes userData;
          }
          /**
           * @dev Emitted for each individual swap performed by `swap` or `batchSwap`.
           */
          event Swap(
              bytes32 indexed poolId,
              IERC20 indexed tokenIn,
              IERC20 indexed tokenOut,
              uint256 amountIn,
              uint256 amountOut
          );
          /**
           * @dev All tokens in a swap are either sent from the `sender` account to the Vault, or from the Vault to the
           * `recipient` account.
           *
           * If the caller is not `sender`, it must be an authorized relayer for them.
           *
           * If `fromInternalBalance` is true, the `sender`'s Internal Balance will be preferred, performing an ERC20
           * transfer for the difference between the requested amount and the User's Internal Balance (if any). The `sender`
           * must have allowed the Vault to use their tokens via `IERC20.approve()`. This matches the behavior of
           * `joinPool`.
           *
           * If `toInternalBalance` is true, tokens will be deposited to `recipient`'s internal balance instead of
           * transferred. This matches the behavior of `exitPool`.
           *
           * Note that ETH cannot be deposited to or withdrawn from Internal Balance: attempting to do so will trigger a
           * revert.
           */
          struct FundManagement {
              address sender;
              bool fromInternalBalance;
              address payable recipient;
              bool toInternalBalance;
          }
          /**
           * @dev Simulates a call to `batchSwap`, returning an array of Vault asset deltas. Calls to `swap` cannot be
           * simulated directly, but an equivalent `batchSwap` call can and will yield the exact same result.
           *
           * Each element in the array corresponds to the asset at the same index, and indicates the number of tokens (or ETH)
           * the Vault would take from the sender (if positive) or send to the recipient (if negative). The arguments it
           * receives are the same that an equivalent `batchSwap` call would receive.
           *
           * Unlike `batchSwap`, this function performs no checks on the sender or recipient field in the `funds` struct.
           * This makes it suitable to be called by off-chain applications via eth_call without needing to hold tokens,
           * approve them for the Vault, or even know a user's address.
           *
           * Note that this function is not 'view' (due to implementation details): the client code must explicitly execute
           * eth_call instead of eth_sendTransaction.
           */
          function queryBatchSwap(
              SwapKind kind,
              BatchSwapStep[] memory swaps,
              IAsset[] memory assets,
              FundManagement memory funds
          ) external returns (int256[] memory assetDeltas);
          // Flash Loans
          /**
           * @dev Performs a 'flash loan', sending tokens to `recipient`, executing the `receiveFlashLoan` hook on it,
           * and then reverting unless the tokens plus a proportional protocol fee have been returned.
           *
           * The `tokens` and `amounts` arrays must have the same length, and each entry in these indicates the loan amount
           * for each token contract. `tokens` must be sorted in ascending order.
           *
           * The 'userData' field is ignored by the Vault, and forwarded as-is to `recipient` as part of the
           * `receiveFlashLoan` call.
           *
           * Emits `FlashLoan` events.
           */
          function flashLoan(
              IFlashLoanRecipient recipient,
              IERC20[] memory tokens,
              uint256[] memory amounts,
              bytes memory userData
          ) external;
          /**
           * @dev Emitted for each individual flash loan performed by `flashLoan`.
           */
          event FlashLoan(IFlashLoanRecipient indexed recipient, IERC20 indexed token, uint256 amount, uint256 feeAmount);
          // Asset Management
          //
          // Each token registered for a Pool can be assigned an Asset Manager, which is able to freely withdraw the Pool's
          // tokens from the Vault, deposit them, or assign arbitrary values to its `managed` balance (see
          // `getPoolTokenInfo`). This makes them extremely powerful and dangerous. Even if an Asset Manager only directly
          // controls one of the tokens in a Pool, a malicious manager could set that token's balance to manipulate the
          // prices of the other tokens, and then drain the Pool with swaps. The risk of using Asset Managers is therefore
          // not constrained to the tokens they are managing, but extends to the entire Pool's holdings.
          //
          // However, a properly designed Asset Manager smart contract can be safely used for the Pool's benefit,
          // for example by lending unused tokens out for interest, or using them to participate in voting protocols.
          //
          // This concept is unrelated to the IAsset interface.
          /**
           * @dev Performs a set of Pool balance operations, which may be either withdrawals, deposits or updates.
           *
           * Pool Balance management features batching, which means a single contract call can be used to perform multiple
           * operations of different kinds, with different Pools and tokens, at once.
           *
           * For each operation, the caller must be registered as the Asset Manager for `token` in `poolId`.
           */
          function managePoolBalance(PoolBalanceOp[] memory ops) external;
          struct PoolBalanceOp {
              PoolBalanceOpKind kind;
              bytes32 poolId;
              IERC20 token;
              uint256 amount;
          }
          /**
           * Withdrawals decrease the Pool's cash, but increase its managed balance, leaving the total balance unchanged.
           *
           * Deposits increase the Pool's cash, but decrease its managed balance, leaving the total balance unchanged.
           *
           * Updates don't affect the Pool's cash balance, but because the managed balance changes, it does alter the total.
           * The external amount can be either increased or decreased by this call (i.e., reporting a gain or a loss).
           */
          enum PoolBalanceOpKind { WITHDRAW, DEPOSIT, UPDATE }
          /**
           * @dev Emitted when a Pool's token Asset Manager alters its balance via `managePoolBalance`.
           */
          event PoolBalanceManaged(
              bytes32 indexed poolId,
              address indexed assetManager,
              IERC20 indexed token,
              int256 cashDelta,
              int256 managedDelta
          );
          // Protocol Fees
          //
          // Some operations cause the Vault to collect tokens in the form of protocol fees, which can then be withdrawn by
          // permissioned accounts.
          //
          // There are two kinds of protocol fees:
          //
          //  - flash loan fees: charged on all flash loans, as a percentage of the amounts lent.
          //
          //  - swap fees: a percentage of the fees charged by Pools when performing swaps. For a number of reasons, including
          // swap gas costs and interface simplicity, protocol swap fees are not charged on each individual swap. Rather,
          // Pools are expected to keep track of how much they have charged in swap fees, and pay any outstanding debts to the
          // Vault when they are joined or exited. This prevents users from joining a Pool with unpaid debt, as well as
          // exiting a Pool in debt without first paying their share.
          /**
           * @dev Returns the current protocol fee module.
           */
          function getProtocolFeesCollector() external view returns (IProtocolFeesCollector);
          /**
           * @dev Safety mechanism to pause most Vault operations in the event of an emergency - typically detection of an
           * error in some part of the system.
           *
           * The Vault can only be paused during an initial time period, after which pausing is forever disabled.
           *
           * While the contract is paused, the following features are disabled:
           * - depositing and transferring internal balance
           * - transferring external balance (using the Vault's allowance)
           * - swaps
           * - joining Pools
           * - Asset Manager interactions
           *
           * Internal Balance can still be withdrawn, and Pools exited.
           */
          function setPaused(bool paused) external;
          /**
           * @dev Returns the Vault's WETH instance.
           */
          function WETH() external view returns (IWETH);
          // solhint-disable-previous-line func-name-mixedcase
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "@balancer-labs/v2-interfaces/contracts/pool-stable/StablePoolUserData.sol";
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      import "@balancer-labs/v2-interfaces/contracts/standalone-utils/IProtocolFeePercentagesProvider.sol";
      import "@balancer-labs/v2-interfaces/contracts/pool-utils/IRateProvider.sol";
      import "@balancer-labs/v2-interfaces/contracts/pool-utils/IVersion.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/math/FixedPoint.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/math/Math.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/helpers/ERC20Helpers.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/helpers/InputHelpers.sol";
      import "@balancer-labs/v2-pool-utils/contracts/BaseGeneralPool.sol";
      import "@balancer-labs/v2-pool-utils/contracts/rates/PriceRateCache.sol";
      import "./ComposableStablePoolStorage.sol";
      import "./ComposableStablePoolRates.sol";
      import "./ComposableStablePoolStorage.sol";
      import "./ComposableStablePoolRates.sol";
      import "./ComposableStablePoolProtocolFees.sol";
      import "./StablePoolAmplification.sol";
      import "./StableMath.sol";
      /**
       * @dev StablePool with preminted BPT and rate providers for each token, allowing for e.g. wrapped tokens with a known
       * price ratio, such as Compound's cTokens.
       *
       * BPT is preminted on Pool initialization and registered as one of the Pool's tokens, allowing for swaps to behave as
       * single-token joins or exits (by swapping a token for BPT). We also support regular joins and exits, which can mint
       * and burn BPT.
       *
       * Preminted BPT is deposited in the Vault as the initial balance of the Pool, and doesn't belong to any entity until
       * transferred out of the Pool. The Pool's arithmetic behaves as if it didn't exist, and the BPT total supply is not
       * a useful value: we rely on the 'virtual supply' (how much BPT is actually owned outside the Vault) instead.
       */
      contract ComposableStablePool is
          IRateProvider,
          IVersion,
          BaseGeneralPool,
          StablePoolAmplification,
          ComposableStablePoolRates,
          ComposableStablePoolProtocolFees
      {
          using FixedPoint for uint256;
          using PriceRateCache for bytes32;
          using StablePoolUserData for bytes;
          using BasePoolUserData for bytes;
          // The maximum imposed by the Vault, which stores balances in a packed format, is 2**(112) - 1.
          // We are preminting half of that value (rounded up).
          uint256 private constant _PREMINTED_TOKEN_BALANCE = 2**(111);
          string private _version;
          // The constructor arguments are received in a struct to work around stack-too-deep issues
          struct NewPoolParams {
              IVault vault;
              IProtocolFeePercentagesProvider protocolFeeProvider;
              string name;
              string symbol;
              IERC20[] tokens;
              IRateProvider[] rateProviders;
              uint256[] tokenRateCacheDurations;
              bool exemptFromYieldProtocolFeeFlag;
              uint256 amplificationParameter;
              uint256 swapFeePercentage;
              uint256 pauseWindowDuration;
              uint256 bufferPeriodDuration;
              address owner;
              string version;
          }
          constructor(NewPoolParams memory params)
              BasePool(
                  params.vault,
                  IVault.PoolSpecialization.GENERAL,
                  params.name,
                  params.symbol,
                  _insertSorted(params.tokens, IERC20(this)),
                  new address[](params.tokens.length + 1),
                  params.swapFeePercentage,
                  params.pauseWindowDuration,
                  params.bufferPeriodDuration,
                  params.owner
              )
              StablePoolAmplification(params.amplificationParameter)
              ComposableStablePoolStorage(_extractStorageParams(params))
              ComposableStablePoolRates(_extractRatesParams(params))
              ProtocolFeeCache(params.protocolFeeProvider, ProtocolFeeCache.DELEGATE_PROTOCOL_SWAP_FEES_SENTINEL)
          {
              _version = params.version;
          }
          // Translate parameters to avoid stack-too-deep issues in the constructor
          function _extractRatesParams(NewPoolParams memory params)
              private
              pure
              returns (ComposableStablePoolRates.RatesParams memory)
          {
              return
                  ComposableStablePoolRates.RatesParams({
                      tokens: params.tokens,
                      rateProviders: params.rateProviders,
                      tokenRateCacheDurations: params.tokenRateCacheDurations
                  });
          }
          // Translate parameters to avoid stack-too-deep issues in the constructor
          function _extractStorageParams(NewPoolParams memory params)
              private
              view
              returns (ComposableStablePoolStorage.StorageParams memory)
          {
              return
                  ComposableStablePoolStorage.StorageParams({
                      registeredTokens: _insertSorted(params.tokens, IERC20(this)),
                      tokenRateProviders: params.rateProviders,
                      exemptFromYieldProtocolFeeFlag: params.exemptFromYieldProtocolFeeFlag
                  });
          }
          function version() external view override returns (string memory) {
              return _version;
          }
          /**
           * @notice Return the minimum BPT balance, required to avoid minimum token balances.
           * @dev This amount is minted and immediately burned on pool initialization, so that the total supply
           * (and therefore post-exit token balances), can never be zero. This keeps the math well-behaved when
           * liquidity is low. (It also provides an easy way to check whether a pool has been initialized, to
           * ensure this is only done once.)
           */
          function getMinimumBpt() external pure returns (uint256) {
              return _getMinimumBpt();
          }
          // BasePool hook
          /**
           * @dev Override base pool hook invoked before any swap, join, or exit to ensure rates are updated before
           * the operation.
           */
          function _beforeSwapJoinExit() internal override {
              super._beforeSwapJoinExit();
              // Before the scaling factors are read, we must update the cached rates, as those will be used to compute the
              // scaling factors.
              // Note that this is not done in a recovery mode exit (since _beforeSwapjoinExit() is not called under those
              // conditions), but this is fine as recovery mode exits are unaffected by scaling factors anyway.
              _cacheTokenRatesIfNecessary();
          }
          // Swap Hooks
          /**
           * @dev Override this hook called by the base class `onSwap`, to check whether we are doing a regular swap,
           * or a swap involving BPT, which is equivalent to a single token join or exit. Since one of the Pool's
           * tokens is the preminted BPT, we need to handle swaps where BPT is involved separately.
           *
           * At this point, the balances are unscaled. The indices are coming from the Vault, so they are indices into
           * the array of registered tokens (including BPT).
           *
           * If this is a swap involving BPT, call `_swapWithBpt`, which computes the amountOut using the swapFeePercentage
           * and charges protocol fees, in the same manner as single token join/exits. Otherwise, perform the default
           * processing for a regular swap.
           */
          function _swapGivenIn(
              SwapRequest memory swapRequest,
              uint256[] memory registeredBalances,
              uint256 registeredIndexIn,
              uint256 registeredIndexOut,
              uint256[] memory scalingFactors
          ) internal virtual override returns (uint256) {
              return
                  (swapRequest.tokenIn == IERC20(this) || swapRequest.tokenOut == IERC20(this))
                      ? _swapWithBpt(swapRequest, registeredBalances, registeredIndexIn, registeredIndexOut, scalingFactors)
                      : super._swapGivenIn(
                          swapRequest,
                          registeredBalances,
                          registeredIndexIn,
                          registeredIndexOut,
                          scalingFactors
                      );
          }
          /**
           * @dev Override this hook called by the base class `onSwap`, to check whether we are doing a regular swap,
           * or a swap involving BPT, which is equivalent to a single token join or exit. Since one of the Pool's
           * tokens is the preminted BPT, we need to handle swaps where BPT is involved separately.
           *
           * At this point, the balances are unscaled. The indices and balances are coming from the Vault, so they
           * refer to the full set of registered tokens (including BPT).
           *
           * If this is a swap involving BPT, call `_swapWithBpt`, which computes the amountOut using the swapFeePercentage
           * and charges protocol fees, in the same manner as single token join/exits. Otherwise, perform the default
           * processing for a regular swap.
           */
          function _swapGivenOut(
              SwapRequest memory swapRequest,
              uint256[] memory registeredBalances,
              uint256 registeredIndexIn,
              uint256 registeredIndexOut,
              uint256[] memory scalingFactors
          ) internal virtual override returns (uint256) {
              return
                  (swapRequest.tokenIn == IERC20(this) || swapRequest.tokenOut == IERC20(this))
                      ? _swapWithBpt(swapRequest, registeredBalances, registeredIndexIn, registeredIndexOut, scalingFactors)
                      : super._swapGivenOut(
                          swapRequest,
                          registeredBalances,
                          registeredIndexIn,
                          registeredIndexOut,
                          scalingFactors
                      );
          }
          /**
           * @dev This is called from the base class `_swapGivenIn`, so at this point the amount has been adjusted
           * for swap fees, and balances have had scaling applied. This will only be called for regular (non-BPT) swaps,
           * so forward to `onRegularSwap`.
           */
          function _onSwapGivenIn(
              SwapRequest memory request,
              uint256[] memory registeredBalances,
              uint256 registeredIndexIn,
              uint256 registeredIndexOut
          ) internal virtual override returns (uint256) {
              return
                  _onRegularSwap(
                      true, // given in
                      request.amount,
                      registeredBalances,
                      registeredIndexIn,
                      registeredIndexOut
                  );
          }
          /**
           * @dev This is called from the base class `_swapGivenOut`, so at this point the amount has been adjusted
           * for swap fees, and balances have had scaling applied. This will only be called for regular (non-BPT) swaps,
           * so forward to `onRegularSwap`.
           */
          function _onSwapGivenOut(
              SwapRequest memory request,
              uint256[] memory registeredBalances,
              uint256 registeredIndexIn,
              uint256 registeredIndexOut
          ) internal virtual override returns (uint256) {
              return
                  _onRegularSwap(
                      false, // given out
                      request.amount,
                      registeredBalances,
                      registeredIndexIn,
                      registeredIndexOut
                  );
          }
          /**
           * @dev Perform a swap between non-BPT tokens. Scaling and fee adjustments have been performed upstream, so
           * all we need to do here is calculate the price quote, depending on the direction of the swap.
           */
          function _onRegularSwap(
              bool isGivenIn,
              uint256 amountGiven,
              uint256[] memory registeredBalances,
              uint256 registeredIndexIn,
              uint256 registeredIndexOut
          ) private view returns (uint256) {
              // Adjust indices and balances for BPT token
              uint256[] memory balances = _dropBptItem(registeredBalances);
              uint256 indexIn = _skipBptIndex(registeredIndexIn);
              uint256 indexOut = _skipBptIndex(registeredIndexOut);
              (uint256 currentAmp, ) = _getAmplificationParameter();
              uint256 invariant = StableMath._calculateInvariant(currentAmp, balances);
              if (isGivenIn) {
                  return StableMath._calcOutGivenIn(currentAmp, balances, indexIn, indexOut, amountGiven, invariant);
              } else {
                  return StableMath._calcInGivenOut(currentAmp, balances, indexIn, indexOut, amountGiven, invariant);
              }
          }
          /**
           * @dev Perform a swap involving the BPT token, equivalent to a single-token join or exit. As with the standard
           * joins and swaps, we first pay any protocol fees pending from swaps that occurred since the previous join or
           * exit, then perform the operation (joinSwap or exitSwap), and finally store the "post operation" invariant and
           * amp, which establishes the new basis for protocol fees.
           *
           * At this point, the scaling factors (including rates) have been computed by the base class, but not yet applied
           * to the balances.
           */
          function _swapWithBpt(
              SwapRequest memory swapRequest,
              uint256[] memory registeredBalances,
              uint256 registeredIndexIn,
              uint256 registeredIndexOut,
              uint256[] memory scalingFactors
          ) private returns (uint256) {
              bool isGivenIn = swapRequest.kind == IVault.SwapKind.GIVEN_IN;
              _upscaleArray(registeredBalances, scalingFactors);
              swapRequest.amount = _upscale(
                  swapRequest.amount,
                  scalingFactors[isGivenIn ? registeredIndexIn : registeredIndexOut]
              );
              (
                  uint256 preJoinExitSupply,
                  uint256[] memory balances,
                  uint256 currentAmp,
                  uint256 preJoinExitInvariant
              ) = _beforeJoinExit(registeredBalances);
              // These calls mutate `balances` so that it holds the post join-exit balances.
              (uint256 amountCalculated, uint256 postJoinExitSupply) = registeredIndexOut == getBptIndex()
                  ? _doJoinSwap(
                      isGivenIn,
                      swapRequest.amount,
                      balances,
                      _skipBptIndex(registeredIndexIn),
                      currentAmp,
                      preJoinExitSupply,
                      preJoinExitInvariant
                  )
                  : _doExitSwap(
                      isGivenIn,
                      swapRequest.amount,
                      balances,
                      _skipBptIndex(registeredIndexOut),
                      currentAmp,
                      preJoinExitSupply,
                      preJoinExitInvariant
                  );
              _updateInvariantAfterJoinExit(
                  currentAmp,
                  balances,
                  preJoinExitInvariant,
                  preJoinExitSupply,
                  postJoinExitSupply
              );
              return
                  isGivenIn
                      ? _downscaleDown(amountCalculated, scalingFactors[registeredIndexOut]) // Amount out, round down
                      : _downscaleUp(amountCalculated, scalingFactors[registeredIndexIn]); // Amount in, round up
          }
          /**
           * @dev This mutates `balances` so that they become the post-joinswap balances. The StableMath interfaces
           * are different depending on the swap direction, so we forward to the appropriate low-level join function.
           */
          function _doJoinSwap(
              bool isGivenIn,
              uint256 amount,
              uint256[] memory balances,
              uint256 indexIn,
              uint256 currentAmp,
              uint256 actualSupply,
              uint256 preJoinExitInvariant
          ) internal view returns (uint256, uint256) {
              return
                  isGivenIn
                      ? _joinSwapExactTokenInForBptOut(
                          amount,
                          balances,
                          indexIn,
                          currentAmp,
                          actualSupply,
                          preJoinExitInvariant
                      )
                      : _joinSwapExactBptOutForTokenIn(
                          amount,
                          balances,
                          indexIn,
                          currentAmp,
                          actualSupply,
                          preJoinExitInvariant
                      );
          }
          /**
           * @dev Since this is a join, we know the tokenOut is BPT. Since it is GivenIn, we know the tokenIn amount,
           * and must calculate the BPT amount out.
           * We are moving preminted BPT out of the Vault, which increases the virtual supply.
           */
          function _joinSwapExactTokenInForBptOut(
              uint256 amountIn,
              uint256[] memory balances,
              uint256 indexIn,
              uint256 currentAmp,
              uint256 actualSupply,
              uint256 preJoinExitInvariant
          ) internal view returns (uint256, uint256) {
              // The StableMath function was created with joins in mind, so it expects a full amounts array. We create an
              // empty one and only set the amount for the token involved.
              uint256[] memory amountsIn = new uint256[](balances.length);
              amountsIn[indexIn] = amountIn;
              uint256 bptOut = StableMath._calcBptOutGivenExactTokensIn(
                  currentAmp,
                  balances,
                  amountsIn,
                  actualSupply,
                  preJoinExitInvariant,
                  getSwapFeePercentage()
              );
              balances[indexIn] = balances[indexIn].add(amountIn);
              uint256 postJoinExitSupply = actualSupply.add(bptOut);
              return (bptOut, postJoinExitSupply);
          }
          /**
           * @dev Since this is a join, we know the tokenOut is BPT. Since it is GivenOut, we know the BPT amount,
           * and must calculate the token amount in.
           * We are moving preminted BPT out of the Vault, which increases the virtual supply.
           */
          function _joinSwapExactBptOutForTokenIn(
              uint256 bptOut,
              uint256[] memory balances,
              uint256 indexIn,
              uint256 currentAmp,
              uint256 actualSupply,
              uint256 preJoinExitInvariant
          ) internal view returns (uint256, uint256) {
              uint256 amountIn = StableMath._calcTokenInGivenExactBptOut(
                  currentAmp,
                  balances,
                  indexIn,
                  bptOut,
                  actualSupply,
                  preJoinExitInvariant,
                  getSwapFeePercentage()
              );
              balances[indexIn] = balances[indexIn].add(amountIn);
              uint256 postJoinExitSupply = actualSupply.add(bptOut);
              return (amountIn, postJoinExitSupply);
          }
          /**
           * @dev This mutates balances so that they become the post-exitswap balances. The StableMath interfaces are
           * different depending on the swap direction, so we forward to the appropriate low-level exit function.
           */
          function _doExitSwap(
              bool isGivenIn,
              uint256 amount,
              uint256[] memory balances,
              uint256 indexOut,
              uint256 currentAmp,
              uint256 actualSupply,
              uint256 preJoinExitInvariant
          ) internal view returns (uint256, uint256) {
              return
                  isGivenIn
                      ? _exitSwapExactBptInForTokenOut(
                          amount,
                          balances,
                          indexOut,
                          currentAmp,
                          actualSupply,
                          preJoinExitInvariant
                      )
                      : _exitSwapExactTokenOutForBptIn(
                          amount,
                          balances,
                          indexOut,
                          currentAmp,
                          actualSupply,
                          preJoinExitInvariant
                      );
          }
          /**
           * @dev Since this is an exit, we know the tokenIn is BPT. Since it is GivenIn, we know the BPT amount,
           * and must calculate the token amount out.
           * We are moving BPT out of circulation and into the Vault, which decreases the virtual supply.
           */
          function _exitSwapExactBptInForTokenOut(
              uint256 bptAmount,
              uint256[] memory balances,
              uint256 indexOut,
              uint256 currentAmp,
              uint256 actualSupply,
              uint256 preJoinExitInvariant
          ) internal view returns (uint256, uint256) {
              uint256 amountOut = StableMath._calcTokenOutGivenExactBptIn(
                  currentAmp,
                  balances,
                  indexOut,
                  bptAmount,
                  actualSupply,
                  preJoinExitInvariant,
                  getSwapFeePercentage()
              );
              balances[indexOut] = balances[indexOut].sub(amountOut);
              uint256 postJoinExitSupply = actualSupply.sub(bptAmount);
              return (amountOut, postJoinExitSupply);
          }
          /**
           * @dev Since this is an exit, we know the tokenIn is BPT. Since it is GivenOut, we know the token amount out,
           * and must calculate the BPT amount in.
           * We are moving BPT out of circulation and into the Vault, which decreases the virtual supply.
           */
          function _exitSwapExactTokenOutForBptIn(
              uint256 amountOut,
              uint256[] memory balances,
              uint256 indexOut,
              uint256 currentAmp,
              uint256 actualSupply,
              uint256 preJoinExitInvariant
          ) internal view returns (uint256, uint256) {
              // The StableMath function was created with exits in mind, so it expects a full amounts array. We create an
              // empty one and only set the amount for the token involved.
              uint256[] memory amountsOut = new uint256[](balances.length);
              amountsOut[indexOut] = amountOut;
              uint256 bptAmount = StableMath._calcBptInGivenExactTokensOut(
                  currentAmp,
                  balances,
                  amountsOut,
                  actualSupply,
                  preJoinExitInvariant,
                  getSwapFeePercentage()
              );
              balances[indexOut] = balances[indexOut].sub(amountOut);
              uint256 postJoinExitSupply = actualSupply.sub(bptAmount);
              return (bptAmount, postJoinExitSupply);
          }
          // Join Hooks
          /**
           * Since this Pool has preminted BPT which is stored in the Vault, it cannot simply be minted at construction.
           *
           * We take advantage of the fact that StablePools have an initialization step where BPT is minted to the first
           * account joining them, and perform both actions at once. By minting the entire BPT supply for the initial joiner
           * and then pulling all tokens except those due the joiner, we arrive at the desired state of the Pool holding all
           * BPT except the joiner's.
           */
          function _onInitializePool(
              bytes32,
              address sender,
              address,
              uint256[] memory scalingFactors,
              bytes memory userData
          ) internal override returns (uint256, uint256[] memory) {
              StablePoolUserData.JoinKind kind = userData.joinKind();
              _require(kind == StablePoolUserData.JoinKind.INIT, Errors.UNINITIALIZED);
              // AmountsIn usually does not include the BPT token; initialization is the one time it has to.
              uint256[] memory amountsInIncludingBpt = userData.initialAmountsIn();
              InputHelpers.ensureInputLengthMatch(amountsInIncludingBpt.length, scalingFactors.length);
              _upscaleArray(amountsInIncludingBpt, scalingFactors);
              (uint256 amp, ) = _getAmplificationParameter();
              uint256[] memory amountsIn = _dropBptItem(amountsInIncludingBpt);
              uint256 invariantAfterJoin = StableMath._calculateInvariant(amp, amountsIn);
              // Set the initial BPT to the value of the invariant
              uint256 bptAmountOut = invariantAfterJoin;
              // BasePool will mint bptAmountOut for the sender: we then also mint the remaining BPT to make up the total
              // supply, and have the Vault pull those tokens from the sender as part of the join.
              // We are only minting half of the maximum value - already an amount many orders of magnitude greater than any
              // conceivable real liquidity - to allow for minting new BPT as a result of regular joins.
              //
              // Note that the sender need not approve BPT for the Vault as the Vault already has infinite BPT allowance for
              // all accounts.
              uint256 initialBpt = _PREMINTED_TOKEN_BALANCE.sub(bptAmountOut);
              _mintPoolTokens(sender, initialBpt);
              amountsInIncludingBpt[getBptIndex()] = initialBpt;
              // Initialization is still a join, so we need to do post-join work.
              _updatePostJoinExit(amp, invariantAfterJoin);
              return (bptAmountOut, amountsInIncludingBpt);
          }
          /**
           * @dev Base pool hook called from `onJoinPool`. Forward to `onJoinExitPool` with `isJoin` set to true.
           */
          function _onJoinPool(
              bytes32,
              address,
              address,
              uint256[] memory registeredBalances,
              uint256,
              uint256,
              uint256[] memory scalingFactors,
              bytes memory userData
          ) internal override returns (uint256, uint256[] memory) {
              return _onJoinExitPool(true, registeredBalances, scalingFactors, userData);
          }
          /**
           * @dev Base pool hook called from `onExitPool`. Forward to `onJoinExitPool` with `isJoin` set to false.
           * Note that recovery mode exits do not call `_onExitPool`.
           */
          function _onExitPool(
              bytes32,
              address,
              address,
              uint256[] memory registeredBalances,
              uint256,
              uint256,
              uint256[] memory scalingFactors,
              bytes memory userData
          ) internal override returns (uint256, uint256[] memory) {
              return _onJoinExitPool(false, registeredBalances, scalingFactors, userData);
          }
          /**
           * @dev Pay protocol fees before the operation, and call `_updateInvariantAfterJoinExit` afterward, to establish
           * the new basis for protocol fees.
           */
          function _onJoinExitPool(
              bool isJoin,
              uint256[] memory registeredBalances,
              uint256[] memory scalingFactors,
              bytes memory userData
          ) internal returns (uint256, uint256[] memory) {
              (
                  uint256 preJoinExitSupply,
                  uint256[] memory balances,
                  uint256 currentAmp,
                  uint256 preJoinExitInvariant
              ) = _beforeJoinExit(registeredBalances);
                  function(uint256[] memory, uint256, uint256, uint256, uint256[] memory, bytes memory)
                      internal
                      view
                      returns (uint256, uint256[] memory) _doJoinOrExit
               = (isJoin ? _doJoin : _doExit);
              (uint256 bptAmount, uint256[] memory amountsDelta) = _doJoinOrExit(
                  balances,
                  currentAmp,
                  preJoinExitSupply,
                  preJoinExitInvariant,
                  scalingFactors,
                  userData
              );
              // Unlike joinswaps, explicit joins do not mutate balances into the post join-exit balances so we must perform
              // this mutation here.
              function(uint256, uint256) internal pure returns (uint256) _addOrSub = isJoin ? FixedPoint.add : FixedPoint.sub;
              _mutateAmounts(balances, amountsDelta, _addOrSub);
              uint256 postJoinExitSupply = _addOrSub(preJoinExitSupply, bptAmount);
              // Pass in the post-join balances to reset the protocol fee basis.
              // We are minting bptAmount, increasing the total (and virtual) supply post-join
              _updateInvariantAfterJoinExit(
                  currentAmp,
                  balances,
                  preJoinExitInvariant,
                  preJoinExitSupply,
                  postJoinExitSupply
              );
              // For clarity and simplicity, arrays used and computed in lower level functions do not include BPT.
              // But the amountsIn array passed back to the Vault must include BPT, so we add it back in here.
              return (bptAmount, _addBptItem(amountsDelta, 0));
          }
          /**
           * @dev Pay any due protocol fees and calculate values necessary for performing the join/exit.
           */
          function _beforeJoinExit(uint256[] memory registeredBalances)
              internal
              returns (
                  uint256,
                  uint256[] memory,
                  uint256,
                  uint256
              )
          {
              (uint256 lastJoinExitAmp, uint256 lastPostJoinExitInvariant) = getLastJoinExitData();
              (
                  uint256 preJoinExitSupply,
                  uint256[] memory balances,
                  uint256 oldAmpPreJoinExitInvariant
              ) = _payProtocolFeesBeforeJoinExit(registeredBalances, lastJoinExitAmp, lastPostJoinExitInvariant);
              // If the amplification factor is the same as it was during the last join/exit then we can reuse the
              // value calculated using the "old" amplification factor. If not, then we have to calculate this now.
              (uint256 currentAmp, ) = _getAmplificationParameter();
              uint256 preJoinExitInvariant = currentAmp == lastJoinExitAmp
                  ? oldAmpPreJoinExitInvariant
                  : StableMath._calculateInvariant(currentAmp, balances);
              return (preJoinExitSupply, balances, currentAmp, preJoinExitInvariant);
          }
          /**
           * @dev Support single- and multi-token joins, plus explicit proportional joins.
           */
          function _doJoin(
              uint256[] memory balances,
              uint256 currentAmp,
              uint256 preJoinExitSupply,
              uint256 preJoinExitInvariant,
              uint256[] memory scalingFactors,
              bytes memory userData
          ) internal view returns (uint256, uint256[] memory) {
              StablePoolUserData.JoinKind kind = userData.joinKind();
              if (kind == StablePoolUserData.JoinKind.EXACT_TOKENS_IN_FOR_BPT_OUT) {
                  return
                      _joinExactTokensInForBPTOut(
                          preJoinExitSupply,
                          preJoinExitInvariant,
                          currentAmp,
                          balances,
                          scalingFactors,
                          userData
                      );
              } else if (kind == StablePoolUserData.JoinKind.ALL_TOKENS_IN_FOR_EXACT_BPT_OUT) {
                  return _joinAllTokensInForExactBptOut(preJoinExitSupply, balances, userData);
              } else if (kind == StablePoolUserData.JoinKind.TOKEN_IN_FOR_EXACT_BPT_OUT) {
                  return _joinTokenInForExactBPTOut(preJoinExitSupply, preJoinExitInvariant, currentAmp, balances, userData);
              } else {
                  _revert(Errors.UNHANDLED_JOIN_KIND);
              }
          }
          /**
           * @dev Proportional join. Pays no swap fees.
           */
          function _joinAllTokensInForExactBptOut(
              uint256 actualSupply,
              uint256[] memory balances,
              bytes memory userData
          ) private pure returns (uint256, uint256[] memory) {
              uint256 bptAmountOut = userData.allTokensInForExactBptOut();
              uint256[] memory amountsIn = StableMath._computeProportionalAmountsIn(balances, bptAmountOut, actualSupply);
              return (bptAmountOut, amountsIn);
          }
          /**
           * @dev Multi-token join. Joins with proportional amounts will pay no protocol fees.
           */
          function _joinExactTokensInForBPTOut(
              uint256 actualSupply,
              uint256 preJoinExitInvariant,
              uint256 currentAmp,
              uint256[] memory balances,
              uint256[] memory scalingFactors,
              bytes memory userData
          ) private view returns (uint256, uint256[] memory) {
              (uint256[] memory amountsIn, uint256 minBPTAmountOut) = userData.exactTokensInForBptOut();
              InputHelpers.ensureInputLengthMatch(balances.length, amountsIn.length);
              // The user-provided amountsIn is unscaled, so we address that.
              _upscaleArray(amountsIn, _dropBptItem(scalingFactors));
              uint256 bptAmountOut = StableMath._calcBptOutGivenExactTokensIn(
                  currentAmp,
                  balances,
                  amountsIn,
                  actualSupply,
                  preJoinExitInvariant,
                  getSwapFeePercentage()
              );
              _require(bptAmountOut >= minBPTAmountOut, Errors.BPT_OUT_MIN_AMOUNT);
              return (bptAmountOut, amountsIn);
          }
          /**
           * @dev Single-token join, equivalent to swapping a pool token for BPT.
           */
          function _joinTokenInForExactBPTOut(
              uint256 actualSupply,
              uint256 preJoinExitInvariant,
              uint256 currentAmp,
              uint256[] memory balances,
              bytes memory userData
          ) private view returns (uint256, uint256[] memory) {
              // Since this index is sent in from the user, we interpret it as NOT including the BPT token.
              (uint256 bptAmountOut, uint256 tokenIndex) = userData.tokenInForExactBptOut();
              // Note that there is no maximum amountIn parameter: this is handled by `IVault.joinPool`.
              // Balances are passed through from the Vault hook, and include BPT
              _require(tokenIndex < balances.length, Errors.OUT_OF_BOUNDS);
              // We join with a single token, so initialize amountsIn with zeros.
              uint256[] memory amountsIn = new uint256[](balances.length);
              // And then assign the result to the selected token.
              amountsIn[tokenIndex] = StableMath._calcTokenInGivenExactBptOut(
                  currentAmp,
                  balances,
                  tokenIndex,
                  bptAmountOut,
                  actualSupply,
                  preJoinExitInvariant,
                  getSwapFeePercentage()
              );
              return (bptAmountOut, amountsIn);
          }
          // Exit Hooks
          /**
           * @dev Support single- and multi-token exits, plus explicit proportional exits (in addition to the
           * recovery mode exit).
           */
          function _doExit(
              uint256[] memory balances,
              uint256 currentAmp,
              uint256 preJoinExitSupply,
              uint256 preJoinExitInvariant,
              uint256[] memory scalingFactors,
              bytes memory userData
          ) internal view returns (uint256, uint256[] memory) {
              StablePoolUserData.ExitKind kind = userData.exitKind();
              if (kind == StablePoolUserData.ExitKind.BPT_IN_FOR_EXACT_TOKENS_OUT) {
                  return
                      _exitBPTInForExactTokensOut(
                          preJoinExitSupply,
                          preJoinExitInvariant,
                          currentAmp,
                          balances,
                          scalingFactors,
                          userData
                      );
              } else if (kind == StablePoolUserData.ExitKind.EXACT_BPT_IN_FOR_ALL_TOKENS_OUT) {
                  return _exitExactBPTInForTokensOut(preJoinExitSupply, balances, userData);
              } else if (kind == StablePoolUserData.ExitKind.EXACT_BPT_IN_FOR_ONE_TOKEN_OUT) {
                  return _exitExactBPTInForTokenOut(preJoinExitSupply, preJoinExitInvariant, currentAmp, balances, userData);
              } else {
                  _revert(Errors.UNHANDLED_EXIT_KIND);
              }
          }
          /**
           * @dev Proportional exit. Pays no swap fees. This is functionally equivalent to the recovery mode exit,
           * except this doesn't skip protocol fee collection, calling rate providers, etc., and doesn't require
           * recovery mode to be enabled.
           */
          function _exitExactBPTInForTokensOut(
              uint256 actualSupply,
              uint256[] memory balances,
              bytes memory userData
          ) private pure returns (uint256, uint256[] memory) {
              uint256 bptAmountIn = userData.exactBptInForTokensOut();
              uint256[] memory amountsOut = _computeProportionalAmountsOut(balances, actualSupply, bptAmountIn);
              return (bptAmountIn, amountsOut);
          }
          /**
           * @dev Multi-token exit. Proportional exits will pay no protocol fees.
           */
          function _exitBPTInForExactTokensOut(
              uint256 actualSupply,
              uint256 preJoinExitInvariant,
              uint256 currentAmp,
              uint256[] memory balances,
              uint256[] memory scalingFactors,
              bytes memory userData
          ) private view returns (uint256, uint256[] memory) {
              (uint256[] memory amountsOut, uint256 maxBPTAmountIn) = userData.bptInForExactTokensOut();
              InputHelpers.ensureInputLengthMatch(amountsOut.length, balances.length);
              // The user-provided amountsIn is unscaled, so we address that.
              _upscaleArray(amountsOut, _dropBptItem(scalingFactors));
              uint256 bptAmountIn = StableMath._calcBptInGivenExactTokensOut(
                  currentAmp,
                  balances,
                  amountsOut,
                  actualSupply,
                  preJoinExitInvariant,
                  getSwapFeePercentage()
              );
              _require(bptAmountIn <= maxBPTAmountIn, Errors.BPT_IN_MAX_AMOUNT);
              return (bptAmountIn, amountsOut);
          }
          /**
           * @dev Single-token exit, equivalent to swapping BPT for a pool token.
           */
          function _exitExactBPTInForTokenOut(
              uint256 actualSupply,
              uint256 preJoinExitInvariant,
              uint256 currentAmp,
              uint256[] memory balances,
              bytes memory userData
          ) private view returns (uint256, uint256[] memory) {
              // Since this index is sent in from the user, we interpret it as NOT including the BPT token
              (uint256 bptAmountIn, uint256 tokenIndex) = userData.exactBptInForTokenOut();
              // Note that there is no minimum amountOut parameter: this is handled by `IVault.exitPool`.
              _require(tokenIndex < balances.length, Errors.OUT_OF_BOUNDS);
              // We exit in a single token, so initialize amountsOut with zeros
              uint256[] memory amountsOut = new uint256[](balances.length);
              // And then assign the result to the selected token.
              amountsOut[tokenIndex] = StableMath._calcTokenOutGivenExactBptIn(
                  currentAmp,
                  balances,
                  tokenIndex,
                  bptAmountIn,
                  actualSupply,
                  preJoinExitInvariant,
                  getSwapFeePercentage()
              );
              return (bptAmountIn, amountsOut);
          }
          /**
           * @dev We cannot use the default RecoveryMode implementation here, since we need to account for the BPT token.
           */
          function _doRecoveryModeExit(
              uint256[] memory registeredBalances,
              uint256,
              bytes memory userData
          ) internal virtual override returns (uint256, uint256[] memory) {
              // Since this Pool uses preminted BPT, we need to replace the total supply with the virtual total supply, and
              // adjust the balances array by removing BPT from it.
              // Note that we don't compute the actual supply, which would require a lot of complex calculations and
              // interactions with external components. This is fine because virtual and actual supply are the same while
              // recovery mode is enabled (since all protocol fees are forfeit and the fee percentages zeroed out).
              (uint256 virtualSupply, uint256[] memory balances) = _dropBptItemFromBalances(registeredBalances);
              (uint256 bptAmountIn, uint256[] memory amountsOut) = super._doRecoveryModeExit(
                  balances,
                  virtualSupply,
                  userData
              );
              // The vault requires an array including BPT, so add it back in here.
              return (bptAmountIn, _addBptItem(amountsOut, 0));
          }
          // BPT rate
          /**
           * Many functions require accessing multiple internal values that might at first seem unrelated, but are actually
           * quite intertwined, and computed at the same time for optimal performance (since calculating some of them also
           * yields intermediate results useful for other queries). This helper function returns many of these values,
           * greatly reducing bytecode size.
           *
           * The return values are:
           *  @return balances - The current upscaled token balances (not including BPT)
           *  @return virtualSupply - The Pool's virtual supply
           *  @return protocolFeeAmount - The amount of unpaid protocol fees in BPT
           *  @return lastJoinExitAmp - The Pool's amplification factor at the last join or exit operation
           *  @return currentInvariantWithLastJoinExitAmp - The invariant of the current balances, calculated using the
           *  amplification factor at the last join or exit operation.
           */
          function _getSupplyAndFeesData()
              private
              view
              returns (
                  uint256[] memory balances,
                  uint256 virtualSupply,
                  uint256 protocolFeeAmount,
                  uint256 lastJoinExitAmp,
                  uint256 currentInvariantWithLastJoinExitAmp
              )
          {
              // First we query the Vault for current registered balances (which includes preminted BPT), to then calculate
              // the current scaled balances and virtual supply.
              (, uint256[] memory registeredBalances, ) = getVault().getPoolTokens(getPoolId());
              _upscaleArray(registeredBalances, _scalingFactors());
              (virtualSupply, balances) = _dropBptItemFromBalances(registeredBalances);
              // Now we need to calculate any BPT due in the form of protocol fees. This requires data from the last join or
              // exit operation. `lastJoinExitAmp` can be useful in the scenario in which the amplification factor has not
              // changed, meaning this old value is equal to the current value.
              uint256 lastPostJoinExitInvariant;
              (lastJoinExitAmp, lastPostJoinExitInvariant) = getLastJoinExitData();
              // Computing the protocol ownership percentage also yields the invariant using the old amplification factor. If
              // it has not changed, then this is also the current invariant.
              uint256 expectedProtocolOwnershipPercentage;
              (
                  expectedProtocolOwnershipPercentage,
                  currentInvariantWithLastJoinExitAmp
              ) = _getProtocolPoolOwnershipPercentage(balances, lastJoinExitAmp, lastPostJoinExitInvariant);
              protocolFeeAmount = ProtocolFees.bptForPoolOwnershipPercentage(
                  virtualSupply,
                  expectedProtocolOwnershipPercentage
              );
          }
          /**
           * @dev This function returns the appreciation of BPT relative to the underlying tokens, as an 18 decimal fixed
           * point number. It is simply the ratio of the invariant to the BPT supply.
           *
           * The total supply is initialized to equal the invariant, so this value starts at one. During Pool operation the
           * invariant always grows and shrinks either proportionally to the total supply (in scenarios with no price impact,
           * e.g. proportional joins), or grows faster and shrinks more slowly than it (whenever swap fees are collected or
           * the token rates increase). Therefore, the rate is a monotonically increasing function.
           *
           * WARNING: since this function reads balances directly from the Vault, it is potentially subject to manipulation
           * via reentrancy if called within a Vault context (i.e. in the middle of a join or an exit). It is up to the
           * caller to ensure that the function is safe to call.
           *
           * This may happen e.g. if one of the tokens in the Pool contains some form of callback behavior in the
           * `transferFrom` function (like ERC777 tokens do). These tokens are strictly incompatible with the
           * Vault and Pool design, and are not safe to be used.
           *
           * There are also other situations where calling this function is unsafe. See
           * https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
           *
           * To call this function safely, attempt to trigger the reentrancy guard in the Vault by calling a non-reentrant
           * function before calling `getRate`. That will make the transaction revert in an unsafe context.
           * (See `whenNotInVaultContext` in `ComposableStablePoolRates`).
           */
          function getRate() external view virtual override returns (uint256) {
              // We need to compute the current invariant and actual total supply. The latter includes protocol fees that have
              // accrued but are not yet minted: in calculating these we'll actually end up fetching most of the data we need
              // for the invariant.
              (
                  uint256[] memory balances,
                  uint256 virtualSupply,
                  uint256 protocolFeeAmount,
                  uint256 lastJoinExitAmp,
                  uint256 currentInvariantWithLastJoinExitAmp
              ) = _getSupplyAndFeesData();
              // Due protocol fees will be minted at the next join or exit, so we can simply add them to the current virtual
              // supply to get the actual supply.
              uint256 actualTotalSupply = virtualSupply.add(protocolFeeAmount);
              // All that's missing now is the invariant. We have the balances required to calculate it already, but still
              // need the current amplification factor.
              (uint256 currentAmp, ) = _getAmplificationParameter();
              // It turns out that the process for due protocol fee calculation involves computing the current invariant,
              // except using the amplification factor at the last join or exit. This would typically not be terribly useful,
              // but since the amplification factor only changes rarely there is high probability of its current value being
              // the same as it was in the last join or exit. If that is the case, then we can skip the costly invariant
              // computation altogether.
              uint256 currentInvariant = (currentAmp == lastJoinExitAmp)
                  ? currentInvariantWithLastJoinExitAmp
                  : StableMath._calculateInvariant(currentAmp, balances);
              // With the current invariant and actual total supply, we can compute the rate as a fixed-point number.
              return currentInvariant.divDown(actualTotalSupply);
          }
          /**
           * @dev Returns the effective BPT supply.
           *
           * In other pools, this would be the same as `totalSupply`, but there are two key differences here:
           *  - this pool pre-mints BPT and holds it in the Vault as a token, and as such we need to subtract the Vault's
           *    balance to get the total "circulating supply". This is called the 'virtualSupply'.
           *  - the Pool owes debt to the Protocol in the form of unminted BPT, which will be minted immediately before the
           *    next join or exit. We need to take these into account since, even if they don't yet exist, they will
           *    effectively be included in any Pool operation that involves BPT.
           *
           * In the vast majority of cases, this function should be used instead of `totalSupply()`.
           *
           * **IMPORTANT NOTE**: calling this function within a Vault context (i.e. in the middle of a join or an exit) is
           * potentially unsafe, since the returned value is manipulable. It is up to the caller to ensure safety.
           *
           * This is because this function calculates the invariant, which requires the state of the pool to be in sync
           * with the state of the Vault. That condition may not be true in the middle of a join or an exit.
           *
           * To call this function safely, attempt to trigger the reentrancy guard in the Vault by calling a non-reentrant
           * function before calling `getActualSupply`. That will make the transaction revert in an unsafe context.
           * (See `whenNotInVaultContext` in `ComposableStablePoolRates`).
           *
           * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
           */
          function getActualSupply() external view returns (uint256) {
              (, uint256 virtualSupply, uint256 protocolFeeAmount, , ) = _getSupplyAndFeesData();
              return virtualSupply.add(protocolFeeAmount);
          }
          /**
           * @dev This function will revert when called within a Vault context (i.e. in the middle of a join or an exit).
           *
           * This function depends on the invariant value, which may be calculated incorrectly in the middle of a join or
           * an exit, because the state of the pool could be out of sync with the state of the Vault. The modifier
           * `whenNotInVaultContext` prevents calling this function (and in turn, the external
           * `updateProtocolFeePercentageCache`) in such a context.
           *
           * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
           */
          function _beforeProtocolFeeCacheUpdate() internal override whenNotInVaultContext {
              // The `getRate()` function depends on the actual supply, which in turn depends on the cached protocol fee
              // percentages. Changing these would therefore result in the rate changing, which is not acceptable as this is a
              // sensitive value.
              // Because of this, we pay any due protocol fees *before* updating the cache, making it so that the new
              // percentages only affect future operation of the Pool, and not past fees. As a result, `getRate()` is
              // unaffected by the cached protocol fee percentages changing.
              // Given that this operation is state-changing and relatively complex, we only allow it as long as the Pool is
              // not paused.
              _ensureNotPaused();
              // We need to calculate the amount of unminted BPT that represents protocol fees to then pay those. This yields
              // some auxiliary values that turn out to also be useful for the rest of the tasks we want to perform.
              (
                  uint256[] memory balances,
                  ,
                  uint256 protocolFeeAmount,
                  uint256 lastJoinExitAmp,
                  uint256 currentInvariantWithLastJoinExitAmp
              ) = _getSupplyAndFeesData();
              if (protocolFeeAmount > 0) {
                  _payProtocolFees(protocolFeeAmount);
              }
              // With the fees paid, we now need to calculate the current invariant so we can store it alongside the current
              // amplification factor, marking the Pool as free of protocol debt.
              (uint256 currentAmp, ) = _getAmplificationParameter();
              // It turns out that the process for due protocol fee calculation involves computing the current invariant,
              // except using the amplification factor at the last join or exit. This would typically not be terribly useful,
              // but since the amplification factor only changes rarely there is high probability of its current value being
              // the same as it was in the last join or exit. If that is the case, then we can skip the costly invariant
              // computation altogether.
              uint256 currentInvariant = (currentAmp == lastJoinExitAmp)
                  ? currentInvariantWithLastJoinExitAmp
                  : StableMath._calculateInvariant(currentAmp, balances);
              _updatePostJoinExit(currentAmp, currentInvariant);
          }
          /**
           * @dev This function will revert when called within a Vault context (i.e. in the middle of a join or an exit).
           *
           * This function depends on the invariant value, which may be calculated incorrectly in the middle of a join or
           * an exit, because the state of the pool could be out of sync with the state of the Vault.
           *
           * The modifier `whenNotInVaultContext` prevents calling this function (and in turn, the external
           * `disableRecoveryMode`) in such a context.
           *
           * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
           */
          function _onDisableRecoveryMode() internal override whenNotInVaultContext {
              // Enabling recovery mode short-circuits protocol fee computations, forcefully returning a zero percentage,
              // increasing the return value of `getRate()` and effectively forfeiting due protocol fees.
              // Therefore, when exiting recovery mode we store the current invariant and the amplification factor used to
              // compute it, marking the Pool as free of protocol debt. Otherwise it'd be possible for debt to be
              // retroactively accrued, which would be incorrect and could lead to the value of `getRate` decreasing.
              (, uint256[] memory registeredBalances, ) = getVault().getPoolTokens(getPoolId());
              _upscaleArray(registeredBalances, _scalingFactors());
              uint256[] memory balances = _dropBptItem(registeredBalances);
              (uint256 currentAmp, ) = _getAmplificationParameter();
              uint256 currentInvariant = StableMath._calculateInvariant(currentAmp, balances);
              _updatePostJoinExit(currentAmp, currentInvariant);
          }
          // Helpers
          /**
           * @dev Mutates `amounts` by applying `mutation` with each entry in `arguments`.
           *
           * Equivalent to `amounts = amounts.map(mutation)`.
           */
          function _mutateAmounts(
              uint256[] memory toMutate,
              uint256[] memory arguments,
              function(uint256, uint256) pure returns (uint256) mutation
          ) private pure {
              uint256 length = toMutate.length;
              InputHelpers.ensureInputLengthMatch(length, arguments.length);
              for (uint256 i = 0; i < length; ++i) {
                  toMutate[i] = mutation(toMutate[i], arguments[i]);
              }
          }
          // Permissioned functions
          /**
           * @dev Inheritance rules still require us to override this in the most derived contract, even though
           * it only calls super.
           */
          function _isOwnerOnlyAction(bytes32 actionId)
              internal
              view
              virtual
              override(
                  // Our inheritance pattern creates a small diamond that requires explicitly listing the parents here.
                  // Each parent calls the `super` version, so linearization ensures all implementations are called.
                  BasePool,
                  ComposableStablePoolProtocolFees,
                  StablePoolAmplification,
                  ComposableStablePoolRates
              )
              returns (bool)
          {
              return super._isOwnerOnlyAction(actionId);
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      /**
       * @dev Interface of the ERC20 standard as defined in the EIP.
       */
      interface IERC20 {
          /**
           * @dev Returns the amount of tokens in existence.
           */
          function totalSupply() external view returns (uint256);
          /**
           * @dev Returns the amount of tokens owned by `account`.
           */
          function balanceOf(address account) external view returns (uint256);
          /**
           * @dev Moves `amount` tokens from the caller's account to `recipient`.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * Emits a {Transfer} event.
           */
          function transfer(address recipient, uint256 amount) external returns (bool);
          /**
           * @dev Returns the remaining number of tokens that `spender` will be
           * allowed to spend on behalf of `owner` through {transferFrom}. This is
           * zero by default.
           *
           * This value changes when {approve} or {transferFrom} are called.
           */
          function allowance(address owner, address spender) external view returns (uint256);
          /**
           * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * IMPORTANT: Beware that changing an allowance with this method brings the risk
           * that someone may use both the old and the new allowance by unfortunate
           * transaction ordering. One possible solution to mitigate this race
           * condition is to first reduce the spender's allowance to 0 and set the
           * desired value afterwards:
           * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
           *
           * Emits an {Approval} event.
           */
          function approve(address spender, uint256 amount) external returns (bool);
          /**
           * @dev Moves `amount` tokens from `sender` to `recipient` using the
           * allowance mechanism. `amount` is then deducted from the caller's
           * allowance.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * Emits a {Transfer} event.
           */
          function transferFrom(
              address sender,
              address recipient,
              uint256 amount
          ) external returns (bool);
          /**
           * @dev Emitted when `value` tokens are moved from one account (`from`) to
           * another (`to`).
           *
           * Note that `value` may be zero.
           */
          event Transfer(address indexed from, address indexed to, uint256 value);
          /**
           * @dev Emitted when the allowance of a `spender` for an `owner` is set by
           * a call to {approve}. `value` is the new allowance.
           */
          event Approval(address indexed owner, address indexed spender, uint256 value);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      interface IAuthentication {
          /**
           * @dev Returns the action identifier associated with the external function described by `selector`.
           */
          function getActionId(bytes4 selector) external view returns (bytes32);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      /**
       * @dev Interface for the SignatureValidator helper, used to support meta-transactions.
       */
      interface ISignaturesValidator {
          /**
           * @dev Returns the EIP712 domain separator.
           */
          function getDomainSeparator() external view returns (bytes32);
          /**
           * @dev Returns the next nonce used by an address to sign messages.
           */
          function getNextNonce(address user) external view returns (uint256);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      /**
       * @dev Interface for the TemporarilyPausable helper.
       */
      interface ITemporarilyPausable {
          /**
           * @dev Emitted every time the pause state changes by `_setPaused`.
           */
          event PausedStateChanged(bool paused);
          /**
           * @dev Returns the current paused state.
           */
          function getPausedState()
              external
              view
              returns (
                  bool paused,
                  uint256 pauseWindowEndTime,
                  uint256 bufferPeriodEndTime
              );
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "../openzeppelin/IERC20.sol";
      /**
       * @dev Interface for WETH9.
       * See https://github.com/gnosis/canonical-weth/blob/0dd1ea3e295eef916d0c6223ec63141137d22d67/contracts/WETH9.sol
       */
      interface IWETH is IERC20 {
          function deposit() external payable;
          function withdraw(uint256 amount) external;
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      /**
       * @dev This is an empty interface used to represent either ERC20-conforming token contracts or ETH (using the zero
       * address sentinel value). We're just relying on the fact that `interface` can be used to declare new address-like
       * types.
       *
       * This concept is unrelated to a Pool's Asset Managers.
       */
      interface IAsset {
          // solhint-disable-previous-line no-empty-blocks
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      interface IAuthorizer {
          /**
           * @dev Returns true if `account` can perform the action described by `actionId` in the contract `where`.
           */
          function canPerform(
              bytes32 actionId,
              address account,
              address where
          ) external view returns (bool);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      // Inspired by Aave Protocol's IFlashLoanReceiver.
      import "../solidity-utils/openzeppelin/IERC20.sol";
      interface IFlashLoanRecipient {
          /**
           * @dev When `flashLoan` is called on the Vault, it invokes the `receiveFlashLoan` hook on the recipient.
           *
           * At the time of the call, the Vault will have transferred `amounts` for `tokens` to the recipient. Before this
           * call returns, the recipient must have transferred `amounts` plus `feeAmounts` for each token back to the
           * Vault, or else the entire flash loan will revert.
           *
           * `userData` is the same value passed in the `IVault.flashLoan` call.
           */
          function receiveFlashLoan(
              IERC20[] memory tokens,
              uint256[] memory amounts,
              uint256[] memory feeAmounts,
              bytes memory userData
          ) external;
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../solidity-utils/openzeppelin/IERC20.sol";
      import "./IVault.sol";
      import "./IAuthorizer.sol";
      interface IProtocolFeesCollector {
          event SwapFeePercentageChanged(uint256 newSwapFeePercentage);
          event FlashLoanFeePercentageChanged(uint256 newFlashLoanFeePercentage);
          function withdrawCollectedFees(
              IERC20[] calldata tokens,
              uint256[] calldata amounts,
              address recipient
          ) external;
          function setSwapFeePercentage(uint256 newSwapFeePercentage) external;
          function setFlashLoanFeePercentage(uint256 newFlashLoanFeePercentage) external;
          function getSwapFeePercentage() external view returns (uint256);
          function getFlashLoanFeePercentage() external view returns (uint256);
          function getCollectedFeeAmounts(IERC20[] memory tokens) external view returns (uint256[] memory feeAmounts);
          function getAuthorizer() external view returns (IAuthorizer);
          function vault() external view returns (IVault);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      /**
       * @dev Source of truth for all Protocol Fee percentages, that is, how much the protocol charges certain actions. Some
       * of these values may also be retrievable from other places (such as the swap fee percentage), but this is the
       * preferred source nonetheless.
       */
      interface IProtocolFeePercentagesProvider {
          // All fee percentages are 18-decimal fixed point numbers, so e.g. 1e18 = 100% and 1e16 = 1%.
          // Emitted when a new fee type is registered.
          event ProtocolFeeTypeRegistered(uint256 indexed feeType, string name, uint256 maximumPercentage);
          // Emitted when the value of a fee type changes.
          // IMPORTANT: it is possible for a third party to modify the SWAP and FLASH_LOAN fee type values directly in the
          // ProtocolFeesCollector, which will result in this event not being emitted despite their value changing. Such usage
          // of the ProtocolFeesCollector is however discouraged: all state-changing interactions with it should originate in
          // this contract.
          event ProtocolFeePercentageChanged(uint256 indexed feeType, uint256 percentage);
          /**
           * @dev Registers a new fee type in the system, making it queryable via `getFeeTypePercentage` and `getFeeTypeName`,
           * as well as configurable via `setFeeTypePercentage`.
           *
           * `feeType` can be any arbitrary value (that is not in use).
           *
           * It is not possible to de-register fee types, nor change their name or maximum value.
           */
          function registerFeeType(
              uint256 feeType,
              string memory name,
              uint256 maximumValue,
              uint256 initialValue
          ) external;
          /**
           * @dev Returns true if `feeType` has been registered and can be queried.
           */
          function isValidFeeType(uint256 feeType) external view returns (bool);
          /**
           * @dev Returns true if `value` is a valid percentage value for `feeType`.
           */
          function isValidFeeTypePercentage(uint256 feeType, uint256 value) external view returns (bool);
          /**
           * @dev Sets the percentage value for `feeType` to `newValue`.
           *
           * IMPORTANT: it is possible for a third party to modify the SWAP and FLASH_LOAN fee type values directly in the
           * ProtocolFeesCollector, without invoking this function. This will result in the `ProtocolFeePercentageChanged`
           * event not being emitted despite their value changing. Such usage of the ProtocolFeesCollector is however
           * discouraged: only this contract should be granted permission to call `setSwapFeePercentage` and
           * `setFlashLoanFeePercentage`.
           */
          function setFeeTypePercentage(uint256 feeType, uint256 newValue) external;
          /**
           * @dev Returns the current percentage value for `feeType`. This is the preferred mechanism for querying these -
           * whenever possible, use this fucntion instead of e.g. querying the ProtocolFeesCollector.
           */
          function getFeeTypePercentage(uint256 feeType) external view returns (uint256);
          /**
           * @dev Returns `feeType`'s maximum value.
           */
          function getFeeTypeMaximumPercentage(uint256 feeType) external view returns (uint256);
          /**
           * @dev Returns `feeType`'s name.
           */
          function getFeeTypeName(uint256 feeType) external view returns (string memory);
      }
      library ProtocolFeeType {
          // This list is not exhaustive - more fee types can be added to the system. It is expected for this list to be
          // extended with new fee types as they are registered, to keep them all in one place and reduce
          // likelihood of user error.
          // solhint-disable private-vars-leading-underscore
          uint256 internal constant SWAP = 0;
          uint256 internal constant FLASH_LOAN = 1;
          uint256 internal constant YIELD = 2;
          uint256 internal constant AUM = 3;
          // solhint-enable private-vars-leading-underscore
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      // solhint-disable
      /**
       * @dev Reverts if `condition` is false, with a revert reason containing `errorCode`. Only codes up to 999 are
       * supported.
       * Uses the default 'BAL' prefix for the error code
       */
      function _require(bool condition, uint256 errorCode) pure {
          if (!condition) _revert(errorCode);
      }
      /**
       * @dev Reverts if `condition` is false, with a revert reason containing `errorCode`. Only codes up to 999 are
       * supported.
       */
      function _require(bool condition, uint256 errorCode, bytes3 prefix) pure {
          if (!condition) _revert(errorCode, prefix);
      }
      /**
       * @dev Reverts with a revert reason containing `errorCode`. Only codes up to 999 are supported.
       * Uses the default 'BAL' prefix for the error code
       */
      function _revert(uint256 errorCode) pure {
          _revert(errorCode, 0x42414c); // This is the raw byte representation of "BAL"
      }
      /**
       * @dev Reverts with a revert reason containing `errorCode`. Only codes up to 999 are supported.
       */
      function _revert(uint256 errorCode, bytes3 prefix) pure {
          uint256 prefixUint = uint256(uint24(prefix));
          // We're going to dynamically create a revert string based on the error code, with the following format:
          // 'BAL#{errorCode}'
          // where the code is left-padded with zeroes to three digits (so they range from 000 to 999).
          //
          // We don't have revert strings embedded in the contract to save bytecode size: it takes much less space to store a
          // number (8 to 16 bits) than the individual string characters.
          //
          // The dynamic string creation algorithm that follows could be implemented in Solidity, but assembly allows for a
          // much denser implementation, again saving bytecode size. Given this function unconditionally reverts, this is a
          // safe place to rely on it without worrying about how its usage might affect e.g. memory contents.
          assembly {
              // First, we need to compute the ASCII representation of the error code. We assume that it is in the 0-999
              // range, so we only need to convert three digits. To convert the digits to ASCII, we add 0x30, the value for
              // the '0' character.
              let units := add(mod(errorCode, 10), 0x30)
              errorCode := div(errorCode, 10)
              let tenths := add(mod(errorCode, 10), 0x30)
              errorCode := div(errorCode, 10)
              let hundreds := add(mod(errorCode, 10), 0x30)
              // With the individual characters, we can now construct the full string.
              // We first append the '#' character (0x23) to the prefix. In the case of 'BAL', it results in 0x42414c23 ('BAL#')
              // Then, we shift this by 24 (to provide space for the 3 bytes of the error code), and add the
              // characters to it, each shifted by a multiple of 8.
              // The revert reason is then shifted left by 200 bits (256 minus the length of the string, 7 characters * 8 bits
              // per character = 56) to locate it in the most significant part of the 256 slot (the beginning of a byte
              // array).
              let formattedPrefix := shl(24, add(0x23, shl(8, prefixUint)))
              let revertReason := shl(200, add(formattedPrefix, add(add(units, shl(8, tenths)), shl(16, hundreds))))
              // We can now encode the reason in memory, which can be safely overwritten as we're about to revert. The encoded
              // message will have the following layout:
              // [ revert reason identifier ] [ string location offset ] [ string length ] [ string contents ]
              // The Solidity revert reason identifier is 0x08c739a0, the function selector of the Error(string) function. We
              // also write zeroes to the next 28 bytes of memory, but those are about to be overwritten.
              mstore(0x0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
              // Next is the offset to the location of the string, which will be placed immediately after (20 bytes away).
              mstore(0x04, 0x0000000000000000000000000000000000000000000000000000000000000020)
              // The string length is fixed: 7 characters.
              mstore(0x24, 7)
              // Finally, the string itself is stored.
              mstore(0x44, revertReason)
              // Even if the string is only 7 bytes long, we need to return a full 32 byte slot containing it. The length of
              // the encoded message is therefore 4 + 32 + 32 + 32 = 100.
              revert(0, 100)
          }
      }
      library Errors {
          // Math
          uint256 internal constant ADD_OVERFLOW = 0;
          uint256 internal constant SUB_OVERFLOW = 1;
          uint256 internal constant SUB_UNDERFLOW = 2;
          uint256 internal constant MUL_OVERFLOW = 3;
          uint256 internal constant ZERO_DIVISION = 4;
          uint256 internal constant DIV_INTERNAL = 5;
          uint256 internal constant X_OUT_OF_BOUNDS = 6;
          uint256 internal constant Y_OUT_OF_BOUNDS = 7;
          uint256 internal constant PRODUCT_OUT_OF_BOUNDS = 8;
          uint256 internal constant INVALID_EXPONENT = 9;
          // Input
          uint256 internal constant OUT_OF_BOUNDS = 100;
          uint256 internal constant UNSORTED_ARRAY = 101;
          uint256 internal constant UNSORTED_TOKENS = 102;
          uint256 internal constant INPUT_LENGTH_MISMATCH = 103;
          uint256 internal constant ZERO_TOKEN = 104;
          // Shared pools
          uint256 internal constant MIN_TOKENS = 200;
          uint256 internal constant MAX_TOKENS = 201;
          uint256 internal constant MAX_SWAP_FEE_PERCENTAGE = 202;
          uint256 internal constant MIN_SWAP_FEE_PERCENTAGE = 203;
          uint256 internal constant MINIMUM_BPT = 204;
          uint256 internal constant CALLER_NOT_VAULT = 205;
          uint256 internal constant UNINITIALIZED = 206;
          uint256 internal constant BPT_IN_MAX_AMOUNT = 207;
          uint256 internal constant BPT_OUT_MIN_AMOUNT = 208;
          uint256 internal constant EXPIRED_PERMIT = 209;
          uint256 internal constant NOT_TWO_TOKENS = 210;
          uint256 internal constant DISABLED = 211;
          // Pools
          uint256 internal constant MIN_AMP = 300;
          uint256 internal constant MAX_AMP = 301;
          uint256 internal constant MIN_WEIGHT = 302;
          uint256 internal constant MAX_STABLE_TOKENS = 303;
          uint256 internal constant MAX_IN_RATIO = 304;
          uint256 internal constant MAX_OUT_RATIO = 305;
          uint256 internal constant MIN_BPT_IN_FOR_TOKEN_OUT = 306;
          uint256 internal constant MAX_OUT_BPT_FOR_TOKEN_IN = 307;
          uint256 internal constant NORMALIZED_WEIGHT_INVARIANT = 308;
          uint256 internal constant INVALID_TOKEN = 309;
          uint256 internal constant UNHANDLED_JOIN_KIND = 310;
          uint256 internal constant ZERO_INVARIANT = 311;
          uint256 internal constant ORACLE_INVALID_SECONDS_QUERY = 312;
          uint256 internal constant ORACLE_NOT_INITIALIZED = 313;
          uint256 internal constant ORACLE_QUERY_TOO_OLD = 314;
          uint256 internal constant ORACLE_INVALID_INDEX = 315;
          uint256 internal constant ORACLE_BAD_SECS = 316;
          uint256 internal constant AMP_END_TIME_TOO_CLOSE = 317;
          uint256 internal constant AMP_ONGOING_UPDATE = 318;
          uint256 internal constant AMP_RATE_TOO_HIGH = 319;
          uint256 internal constant AMP_NO_ONGOING_UPDATE = 320;
          uint256 internal constant STABLE_INVARIANT_DIDNT_CONVERGE = 321;
          uint256 internal constant STABLE_GET_BALANCE_DIDNT_CONVERGE = 322;
          uint256 internal constant RELAYER_NOT_CONTRACT = 323;
          uint256 internal constant BASE_POOL_RELAYER_NOT_CALLED = 324;
          uint256 internal constant REBALANCING_RELAYER_REENTERED = 325;
          uint256 internal constant GRADUAL_UPDATE_TIME_TRAVEL = 326;
          uint256 internal constant SWAPS_DISABLED = 327;
          uint256 internal constant CALLER_IS_NOT_LBP_OWNER = 328;
          uint256 internal constant PRICE_RATE_OVERFLOW = 329;
          uint256 internal constant INVALID_JOIN_EXIT_KIND_WHILE_SWAPS_DISABLED = 330;
          uint256 internal constant WEIGHT_CHANGE_TOO_FAST = 331;
          uint256 internal constant LOWER_GREATER_THAN_UPPER_TARGET = 332;
          uint256 internal constant UPPER_TARGET_TOO_HIGH = 333;
          uint256 internal constant UNHANDLED_BY_LINEAR_POOL = 334;
          uint256 internal constant OUT_OF_TARGET_RANGE = 335;
          uint256 internal constant UNHANDLED_EXIT_KIND = 336;
          uint256 internal constant UNAUTHORIZED_EXIT = 337;
          uint256 internal constant MAX_MANAGEMENT_SWAP_FEE_PERCENTAGE = 338;
          uint256 internal constant UNHANDLED_BY_MANAGED_POOL = 339;
          uint256 internal constant UNHANDLED_BY_PHANTOM_POOL = 340;
          uint256 internal constant TOKEN_DOES_NOT_HAVE_RATE_PROVIDER = 341;
          uint256 internal constant INVALID_INITIALIZATION = 342;
          uint256 internal constant OUT_OF_NEW_TARGET_RANGE = 343;
          uint256 internal constant FEATURE_DISABLED = 344;
          uint256 internal constant UNINITIALIZED_POOL_CONTROLLER = 345;
          uint256 internal constant SET_SWAP_FEE_DURING_FEE_CHANGE = 346;
          uint256 internal constant SET_SWAP_FEE_PENDING_FEE_CHANGE = 347;
          uint256 internal constant CHANGE_TOKENS_DURING_WEIGHT_CHANGE = 348;
          uint256 internal constant CHANGE_TOKENS_PENDING_WEIGHT_CHANGE = 349;
          uint256 internal constant MAX_WEIGHT = 350;
          uint256 internal constant UNAUTHORIZED_JOIN = 351;
          uint256 internal constant MAX_MANAGEMENT_AUM_FEE_PERCENTAGE = 352;
          uint256 internal constant FRACTIONAL_TARGET = 353;
          // Lib
          uint256 internal constant REENTRANCY = 400;
          uint256 internal constant SENDER_NOT_ALLOWED = 401;
          uint256 internal constant PAUSED = 402;
          uint256 internal constant PAUSE_WINDOW_EXPIRED = 403;
          uint256 internal constant MAX_PAUSE_WINDOW_DURATION = 404;
          uint256 internal constant MAX_BUFFER_PERIOD_DURATION = 405;
          uint256 internal constant INSUFFICIENT_BALANCE = 406;
          uint256 internal constant INSUFFICIENT_ALLOWANCE = 407;
          uint256 internal constant ERC20_TRANSFER_FROM_ZERO_ADDRESS = 408;
          uint256 internal constant ERC20_TRANSFER_TO_ZERO_ADDRESS = 409;
          uint256 internal constant ERC20_MINT_TO_ZERO_ADDRESS = 410;
          uint256 internal constant ERC20_BURN_FROM_ZERO_ADDRESS = 411;
          uint256 internal constant ERC20_APPROVE_FROM_ZERO_ADDRESS = 412;
          uint256 internal constant ERC20_APPROVE_TO_ZERO_ADDRESS = 413;
          uint256 internal constant ERC20_TRANSFER_EXCEEDS_ALLOWANCE = 414;
          uint256 internal constant ERC20_DECREASED_ALLOWANCE_BELOW_ZERO = 415;
          uint256 internal constant ERC20_TRANSFER_EXCEEDS_BALANCE = 416;
          uint256 internal constant ERC20_BURN_EXCEEDS_ALLOWANCE = 417;
          uint256 internal constant SAFE_ERC20_CALL_FAILED = 418;
          uint256 internal constant ADDRESS_INSUFFICIENT_BALANCE = 419;
          uint256 internal constant ADDRESS_CANNOT_SEND_VALUE = 420;
          uint256 internal constant SAFE_CAST_VALUE_CANT_FIT_INT256 = 421;
          uint256 internal constant GRANT_SENDER_NOT_ADMIN = 422;
          uint256 internal constant REVOKE_SENDER_NOT_ADMIN = 423;
          uint256 internal constant RENOUNCE_SENDER_NOT_ALLOWED = 424;
          uint256 internal constant BUFFER_PERIOD_EXPIRED = 425;
          uint256 internal constant CALLER_IS_NOT_OWNER = 426;
          uint256 internal constant NEW_OWNER_IS_ZERO = 427;
          uint256 internal constant CODE_DEPLOYMENT_FAILED = 428;
          uint256 internal constant CALL_TO_NON_CONTRACT = 429;
          uint256 internal constant LOW_LEVEL_CALL_FAILED = 430;
          uint256 internal constant NOT_PAUSED = 431;
          uint256 internal constant ADDRESS_ALREADY_ALLOWLISTED = 432;
          uint256 internal constant ADDRESS_NOT_ALLOWLISTED = 433;
          uint256 internal constant ERC20_BURN_EXCEEDS_BALANCE = 434;
          uint256 internal constant INVALID_OPERATION = 435;
          uint256 internal constant CODEC_OVERFLOW = 436;
          uint256 internal constant IN_RECOVERY_MODE = 437;
          uint256 internal constant NOT_IN_RECOVERY_MODE = 438;
          uint256 internal constant INDUCED_FAILURE = 439;
          uint256 internal constant EXPIRED_SIGNATURE = 440;
          uint256 internal constant MALFORMED_SIGNATURE = 441;
          uint256 internal constant SAFE_CAST_VALUE_CANT_FIT_UINT64 = 442;
          uint256 internal constant UNHANDLED_FEE_TYPE = 443;
          // Vault
          uint256 internal constant INVALID_POOL_ID = 500;
          uint256 internal constant CALLER_NOT_POOL = 501;
          uint256 internal constant SENDER_NOT_ASSET_MANAGER = 502;
          uint256 internal constant USER_DOESNT_ALLOW_RELAYER = 503;
          uint256 internal constant INVALID_SIGNATURE = 504;
          uint256 internal constant EXIT_BELOW_MIN = 505;
          uint256 internal constant JOIN_ABOVE_MAX = 506;
          uint256 internal constant SWAP_LIMIT = 507;
          uint256 internal constant SWAP_DEADLINE = 508;
          uint256 internal constant CANNOT_SWAP_SAME_TOKEN = 509;
          uint256 internal constant UNKNOWN_AMOUNT_IN_FIRST_SWAP = 510;
          uint256 internal constant MALCONSTRUCTED_MULTIHOP_SWAP = 511;
          uint256 internal constant INTERNAL_BALANCE_OVERFLOW = 512;
          uint256 internal constant INSUFFICIENT_INTERNAL_BALANCE = 513;
          uint256 internal constant INVALID_ETH_INTERNAL_BALANCE = 514;
          uint256 internal constant INVALID_POST_LOAN_BALANCE = 515;
          uint256 internal constant INSUFFICIENT_ETH = 516;
          uint256 internal constant UNALLOCATED_ETH = 517;
          uint256 internal constant ETH_TRANSFER = 518;
          uint256 internal constant CANNOT_USE_ETH_SENTINEL = 519;
          uint256 internal constant TOKENS_MISMATCH = 520;
          uint256 internal constant TOKEN_NOT_REGISTERED = 521;
          uint256 internal constant TOKEN_ALREADY_REGISTERED = 522;
          uint256 internal constant TOKENS_ALREADY_SET = 523;
          uint256 internal constant TOKENS_LENGTH_MUST_BE_2 = 524;
          uint256 internal constant NONZERO_TOKEN_BALANCE = 525;
          uint256 internal constant BALANCE_TOTAL_OVERFLOW = 526;
          uint256 internal constant POOL_NO_TOKENS = 527;
          uint256 internal constant INSUFFICIENT_FLASH_LOAN_BALANCE = 528;
          // Fees
          uint256 internal constant SWAP_FEE_PERCENTAGE_TOO_HIGH = 600;
          uint256 internal constant FLASH_LOAN_FEE_PERCENTAGE_TOO_HIGH = 601;
          uint256 internal constant INSUFFICIENT_FLASH_LOAN_FEE_AMOUNT = 602;
          uint256 internal constant AUM_FEE_PERCENTAGE_TOO_HIGH = 603;
          // Misc
          uint256 internal constant UNIMPLEMENTED = 998;
          uint256 internal constant SHOULD_NOT_HAPPEN = 999;
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/IAuthentication.sol";
      /**
       * @dev Building block for performing access control on external functions.
       *
       * This contract is used via the `authenticate` modifier (or the `_authenticateCaller` function), which can be applied
       * to external functions to only make them callable by authorized accounts.
       *
       * Derived contracts must implement the `_canPerform` function, which holds the actual access control logic.
       */
      abstract contract Authentication is IAuthentication {
          bytes32 private immutable _actionIdDisambiguator;
          /**
           * @dev The main purpose of the `actionIdDisambiguator` is to prevent accidental function selector collisions in
           * multi contract systems.
           *
           * There are two main uses for it:
           *  - if the contract is a singleton, any unique identifier can be used to make the associated action identifiers
           *    unique. The contract's own address is a good option.
           *  - if the contract belongs to a family that shares action identifiers for the same functions, an identifier
           *    shared by the entire family (and no other contract) should be used instead.
           */
          constructor(bytes32 actionIdDisambiguator) {
              _actionIdDisambiguator = actionIdDisambiguator;
          }
          /**
           * @dev Reverts unless the caller is allowed to call this function. Should only be applied to external functions.
           */
          modifier authenticate() {
              _authenticateCaller();
              _;
          }
          /**
           * @dev Reverts unless the caller is allowed to call the entry point function.
           */
          function _authenticateCaller() internal view {
              bytes32 actionId = getActionId(msg.sig);
              _require(_canPerform(actionId, msg.sender), Errors.SENDER_NOT_ALLOWED);
          }
          function getActionId(bytes4 selector) public view override returns (bytes32) {
              // Each external function is dynamically assigned an action identifier as the hash of the disambiguator and the
              // function selector. Disambiguation is necessary to avoid potential collisions in the function selectors of
              // multiple contracts.
              return keccak256(abi.encodePacked(_actionIdDisambiguator, selector));
          }
          function _canPerform(bytes32 actionId, address user) internal view virtual returns (bool);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      library StablePoolUserData {
          enum JoinKind { INIT, EXACT_TOKENS_IN_FOR_BPT_OUT, TOKEN_IN_FOR_EXACT_BPT_OUT, ALL_TOKENS_IN_FOR_EXACT_BPT_OUT }
          enum ExitKind { EXACT_BPT_IN_FOR_ONE_TOKEN_OUT, BPT_IN_FOR_EXACT_TOKENS_OUT, EXACT_BPT_IN_FOR_ALL_TOKENS_OUT }
          function joinKind(bytes memory self) internal pure returns (JoinKind) {
              return abi.decode(self, (JoinKind));
          }
          function exitKind(bytes memory self) internal pure returns (ExitKind) {
              return abi.decode(self, (ExitKind));
          }
          // Joins
          function initialAmountsIn(bytes memory self) internal pure returns (uint256[] memory amountsIn) {
              (, amountsIn) = abi.decode(self, (JoinKind, uint256[]));
          }
          function exactTokensInForBptOut(bytes memory self)
              internal
              pure
              returns (uint256[] memory amountsIn, uint256 minBPTAmountOut)
          {
              (, amountsIn, minBPTAmountOut) = abi.decode(self, (JoinKind, uint256[], uint256));
          }
          function tokenInForExactBptOut(bytes memory self) internal pure returns (uint256 bptAmountOut, uint256 tokenIndex) {
              (, bptAmountOut, tokenIndex) = abi.decode(self, (JoinKind, uint256, uint256));
          }
          function allTokensInForExactBptOut(bytes memory self) internal pure returns (uint256 bptAmountOut) {
              (, bptAmountOut) = abi.decode(self, (JoinKind, uint256));
          }
          // Exits
          function exactBptInForTokenOut(bytes memory self) internal pure returns (uint256 bptAmountIn, uint256 tokenIndex) {
              (, bptAmountIn, tokenIndex) = abi.decode(self, (ExitKind, uint256, uint256));
          }
          function exactBptInForTokensOut(bytes memory self) internal pure returns (uint256 bptAmountIn) {
              (, bptAmountIn) = abi.decode(self, (ExitKind, uint256));
          }
          function bptInForExactTokensOut(bytes memory self)
              internal
              pure
              returns (uint256[] memory amountsOut, uint256 maxBPTAmountIn)
          {
              (, amountsOut, maxBPTAmountIn) = abi.decode(self, (ExitKind, uint256[], uint256));
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      interface IRateProvider {
          /**
           * @dev Returns an 18 decimal fixed point number that is the exchange rate of the token to some other underlying
           * token. The meaning of this rate depends on the context.
           */
          function getRate() external view returns (uint256);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      import "./LogExpMath.sol";
      /* solhint-disable private-vars-leading-underscore */
      library FixedPoint {
          uint256 internal constant ONE = 1e18; // 18 decimal places
          uint256 internal constant TWO = 2 * ONE;
          uint256 internal constant FOUR = 4 * ONE;
          uint256 internal constant MAX_POW_RELATIVE_ERROR = 10000; // 10^(-14)
          // Minimum base for the power function when the exponent is 'free' (larger than ONE).
          uint256 internal constant MIN_POW_BASE_FREE_EXPONENT = 0.7e18;
          function add(uint256 a, uint256 b) internal pure returns (uint256) {
              // Fixed Point addition is the same as regular checked addition
              uint256 c = a + b;
              _require(c >= a, Errors.ADD_OVERFLOW);
              return c;
          }
          function sub(uint256 a, uint256 b) internal pure returns (uint256) {
              // Fixed Point addition is the same as regular checked addition
              _require(b <= a, Errors.SUB_OVERFLOW);
              uint256 c = a - b;
              return c;
          }
          function mulDown(uint256 a, uint256 b) internal pure returns (uint256) {
              uint256 product = a * b;
              _require(a == 0 || product / a == b, Errors.MUL_OVERFLOW);
              return product / ONE;
          }
          function mulUp(uint256 a, uint256 b) internal pure returns (uint256) {
              uint256 product = a * b;
              _require(a == 0 || product / a == b, Errors.MUL_OVERFLOW);
              if (product == 0) {
                  return 0;
              } else {
                  // The traditional divUp formula is:
                  // divUp(x, y) := (x + y - 1) / y
                  // To avoid intermediate overflow in the addition, we distribute the division and get:
                  // divUp(x, y) := (x - 1) / y + 1
                  // Note that this requires x != 0, which we already tested for.
                  return ((product - 1) / ONE) + 1;
              }
          }
          function divDown(uint256 a, uint256 b) internal pure returns (uint256) {
              _require(b != 0, Errors.ZERO_DIVISION);
              if (a == 0) {
                  return 0;
              } else {
                  uint256 aInflated = a * ONE;
                  _require(aInflated / a == ONE, Errors.DIV_INTERNAL); // mul overflow
                  return aInflated / b;
              }
          }
          function divUp(uint256 a, uint256 b) internal pure returns (uint256) {
              _require(b != 0, Errors.ZERO_DIVISION);
              if (a == 0) {
                  return 0;
              } else {
                  uint256 aInflated = a * ONE;
                  _require(aInflated / a == ONE, Errors.DIV_INTERNAL); // mul overflow
                  // The traditional divUp formula is:
                  // divUp(x, y) := (x + y - 1) / y
                  // To avoid intermediate overflow in the addition, we distribute the division and get:
                  // divUp(x, y) := (x - 1) / y + 1
                  // Note that this requires x != 0, which we already tested for.
                  return ((aInflated - 1) / b) + 1;
              }
          }
          /**
           * @dev Returns x^y, assuming both are fixed point numbers, rounding down. The result is guaranteed to not be above
           * the true value (that is, the error function expected - actual is always positive).
           */
          function powDown(uint256 x, uint256 y) internal pure returns (uint256) {
              // Optimize for when y equals 1.0, 2.0 or 4.0, as those are very simple to implement and occur often in 50/50
              // and 80/20 Weighted Pools
              if (y == ONE) {
                  return x;
              } else if (y == TWO) {
                  return mulDown(x, x);
              } else if (y == FOUR) {
                  uint256 square = mulDown(x, x);
                  return mulDown(square, square);
              } else {
                  uint256 raw = LogExpMath.pow(x, y);
                  uint256 maxError = add(mulUp(raw, MAX_POW_RELATIVE_ERROR), 1);
                  if (raw < maxError) {
                      return 0;
                  } else {
                      return sub(raw, maxError);
                  }
              }
          }
          /**
           * @dev Returns x^y, assuming both are fixed point numbers, rounding up. The result is guaranteed to not be below
           * the true value (that is, the error function expected - actual is always negative).
           */
          function powUp(uint256 x, uint256 y) internal pure returns (uint256) {
              // Optimize for when y equals 1.0, 2.0 or 4.0, as those are very simple to implement and occur often in 50/50
              // and 80/20 Weighted Pools
              if (y == ONE) {
                  return x;
              } else if (y == TWO) {
                  return mulUp(x, x);
              } else if (y == FOUR) {
                  uint256 square = mulUp(x, x);
                  return mulUp(square, square);
              } else {
                  uint256 raw = LogExpMath.pow(x, y);
                  uint256 maxError = add(mulUp(raw, MAX_POW_RELATIVE_ERROR), 1);
                  return add(raw, maxError);
              }
          }
          /**
           * @dev Returns the complement of a value (1 - x), capped to 0 if x is larger than 1.
           *
           * Useful when computing the complement for values with some level of relative error, as it strips this error and
           * prevents intermediate negative values.
           */
          function complement(uint256 x) internal pure returns (uint256) {
              return (x < ONE) ? (ONE - x) : 0;
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      /**
       * @dev Wrappers over Solidity's arithmetic operations with added overflow checks.
       * Adapted from OpenZeppelin's SafeMath library.
       */
      library Math {
          /**
           * @dev Returns the absolute value of a signed integer.
           */
          function abs(int256 a) internal pure returns (uint256) {
              return a > 0 ? uint256(a) : uint256(-a);
          }
          /**
           * @dev Returns the addition of two unsigned integers of 256 bits, reverting on overflow.
           */
          function add(uint256 a, uint256 b) internal pure returns (uint256) {
              uint256 c = a + b;
              _require(c >= a, Errors.ADD_OVERFLOW);
              return c;
          }
          /**
           * @dev Returns the addition of two signed integers, reverting on overflow.
           */
          function add(int256 a, int256 b) internal pure returns (int256) {
              int256 c = a + b;
              _require((b >= 0 && c >= a) || (b < 0 && c < a), Errors.ADD_OVERFLOW);
              return c;
          }
          /**
           * @dev Returns the subtraction of two unsigned integers of 256 bits, reverting on overflow.
           */
          function sub(uint256 a, uint256 b) internal pure returns (uint256) {
              _require(b <= a, Errors.SUB_OVERFLOW);
              uint256 c = a - b;
              return c;
          }
          /**
           * @dev Returns the subtraction of two signed integers, reverting on overflow.
           */
          function sub(int256 a, int256 b) internal pure returns (int256) {
              int256 c = a - b;
              _require((b >= 0 && c <= a) || (b < 0 && c > a), Errors.SUB_OVERFLOW);
              return c;
          }
          /**
           * @dev Returns the largest of two numbers of 256 bits.
           */
          function max(uint256 a, uint256 b) internal pure returns (uint256) {
              return a >= b ? a : b;
          }
          /**
           * @dev Returns the smallest of two numbers of 256 bits.
           */
          function min(uint256 a, uint256 b) internal pure returns (uint256) {
              return a < b ? a : b;
          }
          function mul(uint256 a, uint256 b) internal pure returns (uint256) {
              uint256 c = a * b;
              _require(a == 0 || c / a == b, Errors.MUL_OVERFLOW);
              return c;
          }
          function div(
              uint256 a,
              uint256 b,
              bool roundUp
          ) internal pure returns (uint256) {
              return roundUp ? divUp(a, b) : divDown(a, b);
          }
          function divDown(uint256 a, uint256 b) internal pure returns (uint256) {
              _require(b != 0, Errors.ZERO_DIVISION);
              return a / b;
          }
          function divUp(uint256 a, uint256 b) internal pure returns (uint256) {
              _require(b != 0, Errors.ZERO_DIVISION);
              if (a == 0) {
                  return 0;
              } else {
                  return 1 + (a - 1) / b;
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/openzeppelin/IERC20.sol";
      import "@balancer-labs/v2-interfaces/contracts/vault/IAsset.sol";
      // solhint-disable
      function _asIAsset(IERC20[] memory tokens) pure returns (IAsset[] memory assets) {
          // solhint-disable-next-line no-inline-assembly
          assembly {
              assets := tokens
          }
      }
      function _sortTokens(
          IERC20 tokenA,
          IERC20 tokenB,
          IERC20 tokenC
      ) pure returns (IERC20[] memory tokens) {
          (uint256 indexTokenA, uint256 indexTokenB, uint256 indexTokenC) = _getSortedTokenIndexes(tokenA, tokenB, tokenC);
          tokens = new IERC20[](3);
          tokens[indexTokenA] = tokenA;
          tokens[indexTokenB] = tokenB;
          tokens[indexTokenC] = tokenC;
      }
      function _insertSorted(IERC20[] memory tokens, IERC20 token) pure returns (IERC20[] memory sorted) {
          sorted = new IERC20[](tokens.length + 1);
          if (tokens.length == 0) {
              sorted[0] = token;
              return sorted;
          }
          uint256 i;
          for (i = tokens.length; i > 0 && tokens[i - 1] > token; i--) sorted[i] = tokens[i - 1];
          for (uint256 j = 0; j < i; j++) sorted[j] = tokens[j];
          sorted[i] = token;
      }
      function _appendToken(IERC20[] memory tokens, IERC20 newToken) pure returns (IERC20[] memory newTokens) {
          uint256 numTokens = tokens.length;
          newTokens = new IERC20[](numTokens + 1);
          for (uint256 i = 0; i < numTokens; ++i) newTokens[i] = tokens[i];
          newTokens[numTokens] = newToken;
      }
      function _findTokenIndex(IERC20[] memory tokens, IERC20 token) pure returns (uint256) {
          // Note that while we know tokens are initially sorted, we cannot assume this will hold throughout
          // the pool's lifetime, as pools with mutable tokens can append and remove tokens in any order.
          uint256 tokensLength = tokens.length;
          for (uint256 i = 0; i < tokensLength; i++) {
              if (tokens[i] == token) {
                  return i;
              }
          }
          _revert(Errors.INVALID_TOKEN);
      }
      function _getSortedTokenIndexes(
          IERC20 tokenA,
          IERC20 tokenB,
          IERC20 tokenC
      )
          pure
          returns (
              uint256 indexTokenA,
              uint256 indexTokenB,
              uint256 indexTokenC
          )
      {
          if (tokenA < tokenB) {
              if (tokenB < tokenC) {
                  // (tokenA, tokenB, tokenC)
                  return (0, 1, 2);
              } else if (tokenA < tokenC) {
                  // (tokenA, tokenC, tokenB)
                  return (0, 2, 1);
              } else {
                  // (tokenC, tokenA, tokenB)
                  return (1, 2, 0);
              }
          } else {
              // tokenB < tokenA
              if (tokenC < tokenB) {
                  // (tokenC, tokenB, tokenA)
                  return (2, 1, 0);
              } else if (tokenC < tokenA) {
                  // (tokenB, tokenC, tokenA)
                  return (2, 0, 1);
              } else {
                  // (tokenB, tokenA, tokenC)
                  return (1, 0, 2);
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/openzeppelin/IERC20.sol";
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      library InputHelpers {
          function ensureInputLengthMatch(uint256 a, uint256 b) internal pure {
              _require(a == b, Errors.INPUT_LENGTH_MISMATCH);
          }
          function ensureInputLengthMatch(
              uint256 a,
              uint256 b,
              uint256 c
          ) internal pure {
              _require(a == b && b == c, Errors.INPUT_LENGTH_MISMATCH);
          }
          function ensureArrayIsSorted(IERC20[] memory array) internal pure {
              address[] memory addressArray;
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  addressArray := array
              }
              ensureArrayIsSorted(addressArray);
          }
          function ensureArrayIsSorted(address[] memory array) internal pure {
              if (array.length < 2) {
                  return;
              }
              address previous = array[0];
              for (uint256 i = 1; i < array.length; ++i) {
                  address current = array[i];
                  _require(previous < current, Errors.UNSORTED_ARRAY);
                  previous = current;
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "@balancer-labs/v2-interfaces/contracts/vault/IGeneralPool.sol";
      import "./BasePool.sol";
      /**
       * @dev Extension of `BasePool`, adding a handler for `IGeneralPool.onSwap`.
       *
       * Derived contracts must call `BasePool`'s constructor, and implement `_onSwapGivenIn` and `_onSwapGivenOut` along with
       * `BasePool`'s virtual functions. Inheriting from this contract lets derived contracts choose the General
       * specialization setting.
       */
      abstract contract BaseGeneralPool is IGeneralPool, BasePool {
          // Swap Hooks
          function onSwap(
              SwapRequest memory swapRequest,
              uint256[] memory balances,
              uint256 indexIn,
              uint256 indexOut
          ) external override onlyVault(swapRequest.poolId) returns (uint256) {
              _beforeSwapJoinExit();
              _validateIndexes(indexIn, indexOut, _getTotalTokens());
              uint256[] memory scalingFactors = _scalingFactors();
              return
                  swapRequest.kind == IVault.SwapKind.GIVEN_IN
                      ? _swapGivenIn(swapRequest, balances, indexIn, indexOut, scalingFactors)
                      : _swapGivenOut(swapRequest, balances, indexIn, indexOut, scalingFactors);
          }
          function _swapGivenIn(
              SwapRequest memory swapRequest,
              uint256[] memory balances,
              uint256 indexIn,
              uint256 indexOut,
              uint256[] memory scalingFactors
          ) internal virtual returns (uint256) {
              // Fees are subtracted before scaling, to reduce the complexity of the rounding direction analysis.
              swapRequest.amount = _subtractSwapFeeAmount(swapRequest.amount);
              _upscaleArray(balances, scalingFactors);
              swapRequest.amount = _upscale(swapRequest.amount, scalingFactors[indexIn]);
              uint256 amountOut = _onSwapGivenIn(swapRequest, balances, indexIn, indexOut);
              // amountOut tokens are exiting the Pool, so we round down.
              return _downscaleDown(amountOut, scalingFactors[indexOut]);
          }
          function _swapGivenOut(
              SwapRequest memory swapRequest,
              uint256[] memory balances,
              uint256 indexIn,
              uint256 indexOut,
              uint256[] memory scalingFactors
          ) internal virtual returns (uint256) {
              _upscaleArray(balances, scalingFactors);
              swapRequest.amount = _upscale(swapRequest.amount, scalingFactors[indexOut]);
              uint256 amountIn = _onSwapGivenOut(swapRequest, balances, indexIn, indexOut);
              // amountIn tokens are entering the Pool, so we round up.
              amountIn = _downscaleUp(amountIn, scalingFactors[indexIn]);
              // Fees are added after scaling happens, to reduce the complexity of the rounding direction analysis.
              return _addSwapFeeAmount(amountIn);
          }
          /*
           * @dev Called when a swap with the Pool occurs, where the amount of tokens entering the Pool is known.
           *
           * Returns the amount of tokens that will be taken from the Pool in return.
           *
           * All amounts inside `swapRequest` and `balances` are upscaled. The swap fee has already been deducted from
           * `swapRequest.amount`.
           *
           * The return value is also considered upscaled, and will be downscaled (rounding down) before returning it to the
           * Vault.
           */
          function _onSwapGivenIn(
              SwapRequest memory swapRequest,
              uint256[] memory balances,
              uint256 indexIn,
              uint256 indexOut
          ) internal virtual returns (uint256);
          /*
           * @dev Called when a swap with the Pool occurs, where the amount of tokens exiting the Pool is known.
           *
           * Returns the amount of tokens that will be granted to the Pool in return.
           *
           * All amounts inside `swapRequest` and `balances` are upscaled.
           *
           * The return value is also considered upscaled, and will be downscaled (rounding up) before applying the swap fee
           * and returning it to the Vault.
           */
          function _onSwapGivenOut(
              SwapRequest memory swapRequest,
              uint256[] memory balances,
              uint256 indexIn,
              uint256 indexOut
          ) internal virtual returns (uint256);
          function _validateIndexes(
              uint256 indexIn,
              uint256 indexOut,
              uint256 limit
          ) private pure {
              _require(indexIn < limit && indexOut < limit, Errors.OUT_OF_BOUNDS);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/helpers/WordCodec.sol";
      /**
       * Price rate caches are used to avoid querying the price rate for a token every time we need to work with it. It is
       * useful for slow changing rates, such as those that arise from interest-bearing tokens (e.g. waDAI into DAI).
       *
       * The cache data is packed into a single bytes32 value with the following structure:
       * [ 32 bits |  32 bits  |  96 bits  |    96 bits    ]
       * [ expires | duration  | old rate  | current rate  ]
       * |MSB                                           LSB|
       *
       * 'rate' is an 18 decimal fixed point number, supporting rates of up to ~3e10. 'expires' is a Unix timestamp, and
       * 'duration' is expressed in seconds.
       */
      library PriceRateCache {
          using WordCodec for bytes32;
          uint256 private constant _CURRENT_PRICE_RATE_OFFSET = 0;
          uint256 private constant _OLD_PRICE_RATE_OFFSET = 96;
          uint256 private constant _PRICE_RATE_CACHE_DURATION_OFFSET = 192;
          uint256 private constant _PRICE_RATE_CACHE_EXPIRES_OFFSET = 224;
          uint256 private constant _RATE_BIT_LENGTH = 96;
          uint256 private constant _DURATION_BIT_LENGTH = 32;
          /**
           * @dev Returns the current rate in the price rate cache.
           */
          function getCurrentRate(bytes32 cache) internal pure returns (uint256) {
              return cache.decodeUint(_CURRENT_PRICE_RATE_OFFSET, _RATE_BIT_LENGTH);
          }
          /**
           * @dev Returns the old rate in the price rate cache.
           */
          function getOldRate(bytes32 cache) internal pure returns (uint256) {
              return cache.decodeUint(_OLD_PRICE_RATE_OFFSET, _RATE_BIT_LENGTH);
          }
          /**
           * @dev Copies the current rate to the old rate.
           */
          function updateOldRate(bytes32 cache) internal pure returns (bytes32) {
              return cache.insertUint(getCurrentRate(cache), _OLD_PRICE_RATE_OFFSET, _RATE_BIT_LENGTH);
          }
          /**
           * @dev Returns the duration of a price rate cache.
           */
          function getDuration(bytes32 cache) internal pure returns (uint256) {
              return cache.decodeUint(_PRICE_RATE_CACHE_DURATION_OFFSET, _DURATION_BIT_LENGTH);
          }
          /**
           * @dev Returns the duration and expiration time of a price rate cache.
           */
          function getTimestamps(bytes32 cache) internal pure returns (uint256 duration, uint256 expires) {
              duration = getDuration(cache);
              expires = cache.decodeUint(_PRICE_RATE_CACHE_EXPIRES_OFFSET, _DURATION_BIT_LENGTH);
          }
          /**
           * @dev Encodes rate and duration into a price rate cache. The expiration time is computed automatically, counting
           * from the current time.
           */
          function updateRateAndDuration(
              bytes32 cache,
              uint256 rate,
              uint256 duration
          ) internal view returns (bytes32) {
              _require(rate >> _RATE_BIT_LENGTH == 0, Errors.PRICE_RATE_OVERFLOW);
              // solhint-disable not-rely-on-time
              return
                  cache
                      .insertUint(rate, _CURRENT_PRICE_RATE_OFFSET, _RATE_BIT_LENGTH)
                      .insertUint(duration, _PRICE_RATE_CACHE_DURATION_OFFSET, _DURATION_BIT_LENGTH)
                      .insertUint(block.timestamp + duration, _PRICE_RATE_CACHE_EXPIRES_OFFSET, _DURATION_BIT_LENGTH);
          }
          /**
           * @dev Update the current rate in a price rate cache.
           */
          function updateCurrentRate(bytes32 cache, uint256 rate) internal pure returns (bytes32) {
              _require(rate >> _RATE_BIT_LENGTH == 0, Errors.PRICE_RATE_OVERFLOW);
              return cache.insertUint(rate, _CURRENT_PRICE_RATE_OFFSET, _RATE_BIT_LENGTH);
          }
          /**
           * @dev Update the duration (and expiration) in a price rate cache.
           */
          function updateDuration(bytes32 cache, uint256 duration) internal view returns (bytes32) {
              return
                  cache.insertUint(duration, _PRICE_RATE_CACHE_DURATION_OFFSET, _DURATION_BIT_LENGTH).insertUint(
                      block.timestamp + duration,
                      _PRICE_RATE_CACHE_EXPIRES_OFFSET,
                      _DURATION_BIT_LENGTH
                  );
          }
          /**
           * @dev Returns rate, duration and expiration time of a price rate cache.
           */
          function decode(bytes32 cache)
              internal
              pure
              returns (
                  uint256 rate,
                  uint256 duration,
                  uint256 expires
              )
          {
              rate = getCurrentRate(cache);
              (duration, expires) = getTimestamps(cache);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/openzeppelin/IERC20.sol";
      import "@balancer-labs/v2-interfaces/contracts/pool-utils/IRateProvider.sol";
      import "@balancer-labs/v2-pool-utils/contracts/BasePool.sol";
      import "./StableMath.sol";
      abstract contract ComposableStablePoolStorage is BasePool {
          using FixedPoint for uint256;
          using WordCodec for bytes32;
          struct StorageParams {
              IERC20[] registeredTokens;
              IRateProvider[] tokenRateProviders;
              bool exemptFromYieldProtocolFeeFlag;
          }
          // This minimum refers not to the total tokens, but rather to the non-BPT tokens. The minimum value for _totalTokens
          // is therefore _MIN_NON_BPT_TOKENS + 1.
          uint256 private constant _MIN_NON_BPT_TOKENS = 2;
          // The Pool will register n+1 tokens, where n are the actual tokens in the Pool, and the other one is the BPT
          // itself.
          uint256 private immutable _totalTokens;
          // The index of BPT in the tokens and balances arrays, i.e. its index when calling IVault.registerTokens().
          uint256 private immutable _bptIndex;
          // These are the registered tokens: one of them will be the BPT.
          IERC20 private immutable _token0;
          IERC20 private immutable _token1;
          IERC20 private immutable _token2;
          IERC20 private immutable _token3;
          IERC20 private immutable _token4;
          IERC20 private immutable _token5;
          // All token balances are normalized to behave as if the token had 18 decimals. We assume a token's decimals will
          // not change throughout its lifetime, and store the corresponding scaling factor for each at construction time.
          // These factors are always greater than or equal to one: tokens with more than 18 decimals are not supported.
          uint256 internal immutable _scalingFactor0;
          uint256 internal immutable _scalingFactor1;
          uint256 internal immutable _scalingFactor2;
          uint256 internal immutable _scalingFactor3;
          uint256 internal immutable _scalingFactor4;
          uint256 internal immutable _scalingFactor5;
          // Rate Providers accommodate tokens with a known price ratio, such as Compound's cTokens.
          IRateProvider internal immutable _rateProvider0;
          IRateProvider internal immutable _rateProvider1;
          IRateProvider internal immutable _rateProvider2;
          IRateProvider internal immutable _rateProvider3;
          IRateProvider internal immutable _rateProvider4;
          IRateProvider internal immutable _rateProvider5;
          // This is a bitmap which allows querying whether a token at a particular index:
          // - has a rate provider associated with it.
          // - is exempt from yield protocol fees.
          // This is required as the data stored in this bitmap is computed from values in immutable storage,
          // without this bitmap we would have to manually search through token by token to reach these values.
          // The data structure is as follows:
          //
          // [  unused  | rate provider flags | exemption flags ]
          // [ 244 bits |        6 bits       |     6 bits      ]
          bytes32 private immutable _rateProviderInfoBitmap;
          // Indicates whether all the tokens from the pool are exempt from yield protocol fee or not.
          bool private immutable _exemptFromYieldProtocolFee;
          uint256 private constant _RATE_PROVIDER_FLAGS_OFFSET = 6;
          constructor(StorageParams memory params) {
              // BasePool checks that the Pool has at least two tokens, but since one of them is the BPT (this contract), we
              // need to check ourselves that there are at least creator-supplied tokens (i.e. the minimum number of total
              // tokens for this contract is actually three, including the BPT).
              uint256 totalTokens = params.registeredTokens.length;
              _require(totalTokens > _MIN_NON_BPT_TOKENS, Errors.MIN_TOKENS);
              InputHelpers.ensureInputLengthMatch(totalTokens - 1, params.tokenRateProviders.length);
              _totalTokens = totalTokens;
              // Immutable variables cannot be initialized inside an if statement, so we must do conditional assignments
              _token0 = params.registeredTokens[0];
              _token1 = params.registeredTokens[1];
              _token2 = params.registeredTokens[2];
              _token3 = totalTokens > 3 ? params.registeredTokens[3] : IERC20(0);
              _token4 = totalTokens > 4 ? params.registeredTokens[4] : IERC20(0);
              _token5 = totalTokens > 5 ? params.registeredTokens[5] : IERC20(0);
              _scalingFactor0 = _computeScalingFactor(params.registeredTokens[0]);
              _scalingFactor1 = _computeScalingFactor(params.registeredTokens[1]);
              _scalingFactor2 = _computeScalingFactor(params.registeredTokens[2]);
              _scalingFactor3 = totalTokens > 3 ? _computeScalingFactor(params.registeredTokens[3]) : 0;
              _scalingFactor4 = totalTokens > 4 ? _computeScalingFactor(params.registeredTokens[4]) : 0;
              _scalingFactor5 = totalTokens > 5 ? _computeScalingFactor(params.registeredTokens[5]) : 0;
              // The Vault keeps track of all Pool tokens in a specific order: we need to know what the index of BPT is in
              // this ordering to be able to identify it when balances arrays are received. Since the tokens array is sorted,
              // we need to find the correct BPT index in the array returned by `_insertSorted()`.
              // See `IVault.getPoolTokens()` for more information regarding token ordering.
              uint256 bptIndex;
              for (
                  bptIndex = params.registeredTokens.length - 1;
                  bptIndex > 0 && params.registeredTokens[bptIndex] > IERC20(this);
                  bptIndex--
              ) {
                  // solhint-disable-previous-line no-empty-blocks
              }
              _bptIndex = bptIndex;
              // The rate providers are stored as immutable state variables, and for simplicity when accessing those we'll
              // reference them by token index in the full base tokens plus BPT set (i.e. the tokens the Pool registers). Due
              // to immutable variables requiring an explicit assignment instead of defaulting to an empty value, it is
              // simpler to create a new memory array with the values we want to assign to the immutable state variables.
              IRateProvider[] memory rateProviders = new IRateProvider[](params.registeredTokens.length);
              bytes32 rateProviderInfoBitmap;
              // The exemptFromYieldFlag should never be set on a token without a rate provider.
              // This would cause division by zero errors downstream.
              for (uint256 i = 0; i < params.registeredTokens.length; ++i) {
                  if (i < bptIndex) {
                      rateProviders[i] = params.tokenRateProviders[i];
                  } else if (i != bptIndex) {
                      rateProviders[i] = params.tokenRateProviders[i - 1];
                  } else {
                      // do nothing for i == bptIndex
                      continue;
                  }
                  // Store whether token has rate provider
                  rateProviderInfoBitmap = rateProviderInfoBitmap.insertBool(
                      rateProviders[i] != IRateProvider(0),
                      _RATE_PROVIDER_FLAGS_OFFSET + i
                  );
                  // Store whether token is exempt from yield fees (only with rate providers).
                  if (params.exemptFromYieldProtocolFeeFlag && rateProviders[i] != IRateProvider(0)) {
                      rateProviderInfoBitmap = rateProviderInfoBitmap.insertBool(true, i);
                  }
              }
              // Either all tokens are exempt, or none of them are. This is defined by the input parameter.
              _exemptFromYieldProtocolFee = params.exemptFromYieldProtocolFeeFlag;
              // Immutable variables cannot be initialized inside an if statement, so we must do conditional assignments
              _rateProvider0 = rateProviders[0];
              _rateProvider1 = rateProviders[1];
              _rateProvider2 = rateProviders[2];
              _rateProvider3 = (rateProviders.length > 3) ? rateProviders[3] : IRateProvider(0);
              _rateProvider4 = (rateProviders.length > 4) ? rateProviders[4] : IRateProvider(0);
              _rateProvider5 = (rateProviders.length > 5) ? rateProviders[5] : IRateProvider(0);
              _rateProviderInfoBitmap = rateProviderInfoBitmap;
          }
          // Tokens
          function _getTotalTokens() internal view virtual override returns (uint256) {
              return _totalTokens;
          }
          function _getMaxTokens() internal pure override returns (uint256) {
              // The BPT will be one of the Pool tokens, but it is unaffected by the Stable 5 token limit.
              return StableMath._MAX_STABLE_TOKENS + 1;
          }
          function getBptIndex() public view returns (uint256) {
              return _bptIndex;
          }
          function _getTokenIndex(IERC20 token) internal view returns (uint256) {
              if (token == _token0) return 0;
              if (token == _token1) return 1;
              if (token == _token2) return 2;
              if (token == _token3) return 3;
              if (token == _token4) return 4;
              if (token == _token5) return 5;
              _revert(Errors.INVALID_TOKEN);
          }
          function _scalingFactor(IERC20) internal view virtual override returns (uint256) {
              // We never use a single token's scaling factor by itself, we always process the entire array at once.
              // Therefore we don't bother providing an implementation for this.
              _revert(Errors.UNIMPLEMENTED);
          }
          // Index helpers
          // Convert from an index into an array including BPT (the Vault's registered token list), to an index
          // into an array excluding BPT (usually from user input, such as amountsIn/Out).
          // `index` must not be the BPT token index itself.
          function _skipBptIndex(uint256 index) internal view returns (uint256) {
              // Currently this is never called with an index passed in from user input, so this check
              // should not be necessary. Included for completion (and future proofing).
              _require(index != getBptIndex(), Errors.OUT_OF_BOUNDS);
              return index < getBptIndex() ? index : index.sub(1);
          }
          /**
           * @dev Remove the item at `_bptIndex` from an arbitrary array (e.g., amountsIn).
           */
          function _dropBptItem(uint256[] memory amounts) internal view returns (uint256[] memory) {
              uint256[] memory amountsWithoutBpt = new uint256[](amounts.length - 1);
              for (uint256 i = 0; i < amountsWithoutBpt.length; i++) {
                  amountsWithoutBpt[i] = amounts[i < getBptIndex() ? i : i + 1];
              }
              return amountsWithoutBpt;
          }
          /**
           * @dev Same as `_dropBptItem`, except the virtual supply is also returned, and `balances` is assumed to be the
           * current Pool balances (including BPT).
           */
          function _dropBptItemFromBalances(uint256[] memory registeredBalances)
              internal
              view
              returns (uint256, uint256[] memory)
          {
              return (_getVirtualSupply(registeredBalances[getBptIndex()]), _dropBptItem(registeredBalances));
          }
          // Convert from an index into an array excluding BPT (usually from user input, such as amountsIn/Out),
          // to an index into an array including BPT (the Vault's registered token list).
          // `index` must not be the BPT token index itself, if it is the last element, and the result must be
          // in the range of registered tokens.
          function _addBptIndex(uint256 index) internal view returns (uint256 registeredIndex) {
              // This can be called from an index passed in from user input.
              registeredIndex = index < getBptIndex() ? index : index.add(1);
              // TODO: `indexWithBpt != getBptIndex()` follows from above line and so can be removed.
              _require(registeredIndex < _totalTokens && registeredIndex != getBptIndex(), Errors.OUT_OF_BOUNDS);
          }
          /**
           * @dev Take an array of arbitrary values the size of the token set without BPT, and insert the given
           * bptAmount at the bptIndex location.
           *
           * The caller is responsible for ensuring the `amounts` input array is sized properly; this function
           * performs no checks.
           */
          function _addBptItem(uint256[] memory amounts, uint256 bptAmount)
              internal
              view
              returns (uint256[] memory registeredTokenAmounts)
          {
              registeredTokenAmounts = new uint256[](amounts.length + 1);
              for (uint256 i = 0; i < registeredTokenAmounts.length; i++) {
                  registeredTokenAmounts[i] = i == getBptIndex() ? bptAmount : amounts[i < getBptIndex() ? i : i - 1];
              }
          }
          // Rate Providers
          function _getScalingFactor(uint256 index) internal view returns (uint256) {
              if (index == 0) return _scalingFactor0;
              if (index == 1) return _scalingFactor1;
              if (index == 2) return _scalingFactor2;
              if (index == 3) return _scalingFactor3;
              if (index == 4) return _scalingFactor4;
              if (index == 5) return _scalingFactor5;
              else {
                  _revert(Errors.INVALID_TOKEN);
              }
          }
          /**
           * @dev Returns the rate providers configured for each token (in the same order as registered).
           */
          function getRateProviders() external view returns (IRateProvider[] memory) {
              uint256 totalTokens = _getTotalTokens();
              IRateProvider[] memory providers = new IRateProvider[](totalTokens);
              for (uint256 i = 0; i < totalTokens; ++i) {
                  providers[i] = _getRateProvider(i);
              }
              return providers;
          }
          function _getRateProvider(uint256 index) internal view returns (IRateProvider) {
              if (index == 0) return _rateProvider0;
              if (index == 1) return _rateProvider1;
              if (index == 2) return _rateProvider2;
              if (index == 3) return _rateProvider3;
              if (index == 4) return _rateProvider4;
              if (index == 5) return _rateProvider5;
              else {
                  _revert(Errors.INVALID_TOKEN);
              }
          }
          /**
           * @notice Return true if the token at this index has a rate provider
           */
          function _hasRateProvider(uint256 tokenIndex) internal view returns (bool) {
              return _rateProviderInfoBitmap.decodeBool(_RATE_PROVIDER_FLAGS_OFFSET + tokenIndex);
          }
          /**
           * @notice Return true if all tokens are exempt from yield fees.
           */
          function isExemptFromYieldProtocolFee() public view returns (bool) {
              return _exemptFromYieldProtocolFee;
          }
          /**
           * @dev Returns whether the token is exempt from protocol fees on the yield.
           * If the BPT token is passed in (which doesn't make much sense, but shouldn't fail,
           * since it is a valid pool token), the corresponding flag will be false.
           */
          function isTokenExemptFromYieldProtocolFee(IERC20 token) external view returns (bool) {
              return _exemptFromYieldProtocolFee && _hasRateProvider(_getTokenIndex(token));
          }
          // Virtual Supply
          /**
           * @dev Returns the number of tokens in circulation.
           *
           * WARNING: in the vast majority of cases this is not a useful value, since it does not include the debt the Pool
           * accrued in the form of unminted BPT for the ProtocolFeesCollector. Look into `getActualSupply()` and how that's
           * different.
           *
           * In other pools, this would be the same as `totalSupply`, but since this pool pre-mints BPT and holds it in the
           * Vault as a token, we need to subtract the Vault's balance to get the total "circulating supply". Both the
           * totalSupply and Vault balance can change. If users join or exit using swaps, some of the preminted BPT are
           * exchanged, so the Vault's balance increases after joins and decreases after exits. If users call the regular
           * joins/exit functions, the totalSupply can change as BPT are minted for joins or burned for exits.
           */
          function _getVirtualSupply(uint256 bptBalance) internal view returns (uint256) {
              // The initial amount of BPT pre-minted is _PREMINTED_TOKEN_BALANCE, and it goes entirely to the pool balance in
              // the vault. So the virtualSupply (the amount of BPT supply in circulation) is defined as:
              // virtualSupply = totalSupply() - _balances[_bptIndex]
              return totalSupply().sub(bptBalance);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/openzeppelin/IERC20.sol";
      import "@balancer-labs/v2-interfaces/contracts/pool-utils/IRateProvider.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/helpers/ERC20Helpers.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/helpers/InputHelpers.sol";
      import "@balancer-labs/v2-pool-utils/contracts/rates/PriceRateCache.sol";
      import "./ComposableStablePoolStorage.sol";
      abstract contract ComposableStablePoolRates is ComposableStablePoolStorage {
          using PriceRateCache for bytes32;
          using FixedPoint for uint256;
          struct RatesParams {
              IERC20[] tokens;
              IRateProvider[] rateProviders;
              uint256[] tokenRateCacheDurations;
          }
          // Token rate caches are used to avoid querying the price rate for a token every time we need to work with it.
          // The "old rate" field is used for precise protocol fee calculation, to ensure that token yield is only
          // "taxed" once. The data structure is as follows:
          //
          // [ expires | duration | old rate | current rate ]
          // [ uint32  |  uint32  |  uint96  |   uint96     ]
          // Since we never need just one cache but all of them at once, instead of making the mapping go from token address
          // to cache, we go from token index (including BPT), i.e. an array. We use a mapping however instead of a native
          // array to skip the extra read associated with the out-of-bounds check, as we have cheaper ways to guarantee the
          // indices are valid.
          mapping(uint256 => bytes32) internal _tokenRateCaches;
          event TokenRateCacheUpdated(uint256 indexed tokenIndex, uint256 rate);
          event TokenRateProviderSet(uint256 indexed tokenIndex, IRateProvider indexed provider, uint256 cacheDuration);
          constructor(RatesParams memory rateParams) {
              InputHelpers.ensureInputLengthMatch(
                  rateParams.tokens.length,
                  rateParams.rateProviders.length,
                  rateParams.tokenRateCacheDurations.length
              );
              IERC20[] memory registeredTokens = _insertSorted(rateParams.tokens, IERC20(this));
              uint256 bptIndex;
              for (
                  bptIndex = registeredTokens.length - 1;
                  bptIndex > 0 && registeredTokens[bptIndex] > IERC20(this);
                  bptIndex--
              ) {
                  // solhint-disable-previous-line no-empty-blocks
              }
              uint256 skipBpt = 0;
              for (uint256 i = 0; i < rateParams.tokens.length; i++) {
                  if (i == bptIndex) {
                      skipBpt = 1;
                  }
                  uint256 k = i + skipBpt;
                  if (rateParams.rateProviders[i] != IRateProvider(0)) {
                      _updateTokenRateCache(k, rateParams.rateProviders[i], rateParams.tokenRateCacheDurations[i]);
                      emit TokenRateProviderSet(k, rateParams.rateProviders[i], rateParams.tokenRateCacheDurations[i]);
                      // Initialize the old rates as well, in case they are referenced before the first join.
                      _updateOldRate(k);
                  }
              }
          }
          /**
           * @dev Ensure we are not in a Vault context when this function is called, by attempting a no-op internal
           * balance operation. If we are already in a Vault transaction (e.g., a swap, join, or exit), the Vault's
           * reentrancy protection will cause this function to revert.
           *
           * The exact function call doesn't really matter: we're just trying to trigger the Vault reentrancy check
           * (and not hurt anything in case it works). An empty operation array with no specific operation at all works
           * for that purpose, and is also the least expensive in terms of gas and bytecode size.
           *
           * Use this modifier with any function that can cause a state change in a pool and is either public itself,
           * or called by a public function *outside* a Vault operation (e.g., join, exit, or swap).
           * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
           */
          modifier whenNotInVaultContext() {
              _ensureNotInVaultContext();
              _;
          }
          /**
           * @dev Reverts if called in the middle of a Vault operation; has no effect otherwise.
           */
          function _ensureNotInVaultContext() private {
              IVault.UserBalanceOp[] memory noop = new IVault.UserBalanceOp[](0);
              getVault().manageUserBalance(noop);
          }
          /**
           * @dev Updates the old rate for the token at `index` (including BPT). Assumes `index` is valid.
           */
          function _updateOldRate(uint256 index) internal {
              bytes32 cache = _tokenRateCaches[index];
              _tokenRateCaches[index] = cache.updateOldRate();
          }
          /**
           * @dev Returns the rate for a given token. All token rates are fixed-point values with 18 decimals.
           * If there is no rate provider for the provided token, it returns FixedPoint.ONE.
           */
          function getTokenRate(IERC20 token) external view returns (uint256) {
              return _getTokenRate(_getTokenIndex(token));
          }
          function _getTokenRate(uint256 index) internal view virtual returns (uint256) {
              // We optimize for the scenario where all tokens have rate providers, except the BPT (which never has a rate
              // provider). Therefore, we return early if `token` is the BPT, and otherwise optimistically read the cache
              // expecting that it will not be empty (instead of e.g. fetching the provider to avoid a cache read, since
              // we don't need the provider at all).
              if (index == getBptIndex()) {
                  return FixedPoint.ONE;
              }
              bytes32 tokenRateCache = _tokenRateCaches[index];
              return tokenRateCache == bytes32(0) ? FixedPoint.ONE : tokenRateCache.getCurrentRate();
          }
          /**
           * @dev Returns the cached value for token's rate. Reverts if the token doesn't belong to the pool or has no rate
           * provider.
           */
          function getTokenRateCache(IERC20 token)
              external
              view
              returns (
                  uint256 rate,
                  uint256 oldRate,
                  uint256 duration,
                  uint256 expires
              )
          {
              bytes32 cache = _tokenRateCaches[_getTokenIndex(token)];
              // A zero cache indicates that the token doesn't have a rate provider associated with it.
              _require(cache != bytes32(0), Errors.TOKEN_DOES_NOT_HAVE_RATE_PROVIDER);
              rate = cache.getCurrentRate();
              oldRate = cache.getOldRate();
              (duration, expires) = cache.getTimestamps();
          }
          /**
           * @dev Sets a new duration for a token rate cache.
           * Note this function also updates the current cached value.
           *
           * This function will revert when called within a Vault context (i.e. in the middle of a join or an exit).
           *
           * This function depends on `getRate` via the rate provider, which may be calculated incorrectly in the middle of a
           * join or an exit because the state of the pool could be out of sync with the state of the Vault.
           *
           * It will also revert if there was no rate provider set initially.
           *
           * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
           *
           * @param duration Number of seconds until the current token rate is fetched again.
           */
          function setTokenRateCacheDuration(IERC20 token, uint256 duration) external authenticate whenNotInVaultContext {
              uint256 index = _getTokenIndex(token);
              IRateProvider provider = _getRateProvider(index);
              _require(address(provider) != address(0), Errors.TOKEN_DOES_NOT_HAVE_RATE_PROVIDER);
              _updateTokenRateCache(index, provider, duration);
              emit TokenRateProviderSet(index, provider, duration);
          }
          /**
           * @dev Forces a rate cache hit for a token.
           *
           * This function will revert when called within a Vault context (i.e. in the middle of a join or an exit).
           *
           * This function depends on `getRate` via the rate provider, which may be calculated incorrectly in the middle of a
           * join or an exit because the state of the pool could be out of sync with the state of the Vault.
           *
           * It will also revert if the requested token does not have an associated rate provider.
           *
           * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
           */
          function updateTokenRateCache(IERC20 token) external whenNotInVaultContext {
              uint256 index = _getTokenIndex(token);
              IRateProvider provider = _getRateProvider(index);
              _require(address(provider) != address(0), Errors.TOKEN_DOES_NOT_HAVE_RATE_PROVIDER);
              uint256 duration = _tokenRateCaches[index].getDuration();
              _updateTokenRateCache(index, provider, duration);
          }
          /**
           * @dev Internal function to update a token rate cache for a known provider and duration.
           * It trusts the given values, and does not perform any checks.
           */
          function _updateTokenRateCache(
              uint256 index,
              IRateProvider provider,
              uint256 duration
          ) internal virtual {
              uint256 rate = provider.getRate();
              bytes32 cache = _tokenRateCaches[index];
              _tokenRateCaches[index] = cache.updateRateAndDuration(rate, duration);
              emit TokenRateCacheUpdated(index, rate);
          }
          /**
           * @dev Caches the rates of all tokens if necessary
           */
          function _cacheTokenRatesIfNecessary() internal {
              uint256 totalTokens = _getTotalTokens();
              for (uint256 i = 0; i < totalTokens; ++i) {
                  _cacheTokenRateIfNecessary(i);
              }
          }
          /**
           * @dev Caches the rate for a token if necessary. It ignores the call if there is no provider set.
           */
          function _cacheTokenRateIfNecessary(uint256 index) internal {
              // We optimize for the scenario where all tokens have rate providers, except the BPT (which never has a rate
              // provider). Therefore, we return early if token is BPT, and otherwise optimistically read the cache expecting
              // that it will not be empty (instead of e.g. fetching the provider to avoid a cache read in situations where
              // we might not need the provider if the cache is still valid).
              if (index == getBptIndex()) return;
              bytes32 cache = _tokenRateCaches[index];
              if (cache != bytes32(0)) {
                  (uint256 duration, uint256 expires) = cache.getTimestamps();
                  if (block.timestamp > expires) {
                      // solhint-disable-previous-line not-rely-on-time
                      _updateTokenRateCache(index, _getRateProvider(index), duration);
                  }
              }
          }
          // To compute the yield protocol fees, we need the oldRate for all tokens, even if the exempt flag is not set.
          // We do need to ensure the token has a rate provider before updating; otherwise it will not be in the cache.
          function _updateOldRates() internal {
              uint256 totalTokens = _getTotalTokens();
              for (uint256 i = 0; i < totalTokens; ++i) {
                  if (_hasRateProvider(i)) _updateOldRate(i);
              }
          }
          /**
           * @dev Apply the token ratios to a set of balances, only if they have a rate provider.
           * The `balances` array is assumed to not include BPT to ensure that token indices align.
           */
          function _getAdjustedBalances(uint256[] memory balances) internal view returns (uint256[] memory) {
              uint256 totalTokensWithoutBpt = balances.length;
              uint256[] memory adjustedBalances = new uint256[](totalTokensWithoutBpt);
              for (uint256 i = 0; i < totalTokensWithoutBpt; ++i) {
                  uint256 skipBptIndex = i >= getBptIndex() ? i + 1 : i;
                  adjustedBalances[i] = _hasRateProvider(skipBptIndex)
                      ? _adjustedBalance(balances[i], _tokenRateCaches[skipBptIndex])
                      : balances[i];
              }
              return adjustedBalances;
          }
          // Compute balance * oldRate/currentRate, doing division last to minimize rounding error.
          function _adjustedBalance(uint256 balance, bytes32 cache) private pure returns (uint256) {
              return Math.divDown(Math.mul(balance, cache.getOldRate()), cache.getCurrentRate());
          }
          // Scaling Factors
          /**
           * @dev Overrides scaling factor getter to compute the tokens' rates.
           */
          function _scalingFactors() internal view virtual override returns (uint256[] memory) {
              // There is no need to check the arrays length since both are based on `_getTotalTokens`
              uint256 totalTokens = _getTotalTokens();
              uint256[] memory scalingFactors = new uint256[](totalTokens);
              for (uint256 i = 0; i < totalTokens; ++i) {
                  scalingFactors[i] = _getScalingFactor(i).mulDown(_getTokenRate(i));
              }
              return scalingFactors;
          }
          /**
           * @dev Overrides only owner action to allow setting the cache duration for the token rates
           */
          function _isOwnerOnlyAction(bytes32 actionId) internal view virtual override returns (bool) {
              return (actionId == getActionId(this.setTokenRateCacheDuration.selector)) || super._isOwnerOnlyAction(actionId);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "@balancer-labs/v2-solidity-utils/contracts/math/FixedPoint.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/helpers/WordCodec.sol";
      import "@balancer-labs/v2-pool-utils/contracts/protocol-fees/ProtocolFeeCache.sol";
      import "@balancer-labs/v2-pool-utils/contracts/protocol-fees/InvariantGrowthProtocolSwapFees.sol";
      import "./ComposableStablePoolStorage.sol";
      import "./ComposableStablePoolRates.sol";
      import "./StableMath.sol";
      abstract contract ComposableStablePoolProtocolFees is
          ComposableStablePoolStorage,
          ComposableStablePoolRates,
          ProtocolFeeCache
      {
          using FixedPoint for uint256;
          using WordCodec for bytes32;
          // To track protocol fees, we measure and store the value of the invariant after every join and exit.
          // All invariant growth that happens between join and exit events is due to swap fees and yield.
          // For selected tokens, we exclude the yield portion from the computation.
          // Because the invariant depends on the amplification parameter, and this value may change over time, we should only
          // compare invariants that were computed using the same value. We therefore store both values together.
          //
          // These values reside in the same storage slot. The amplification factor is bound by _MAX_AMP * _AMP_PRECISION, or
          // 5e6, which fits in 23 bits. We use all remaining bits for the invariant: this is more than enough, as the
          // invariant is proportional to the total supply, which is capped at 112 bits.
          // The data structure is as follows:
          //
          // [ last join-exit amplification  | last post join-exit invariant ]
          // [           23 bits             |            233 bits           ]
          bytes32 private _lastJoinExitData;
          uint256 private constant _LAST_POST_JOIN_EXIT_INVARIANT_OFFSET = 0;
          uint256 private constant _LAST_POST_JOIN_EXIT_INVARIANT_SIZE = 233;
          uint256 private constant _LAST_JOIN_EXIT_AMPLIFICATION_OFFSET = _LAST_POST_JOIN_EXIT_INVARIANT_OFFSET +
              _LAST_POST_JOIN_EXIT_INVARIANT_SIZE;
          uint256 private constant _LAST_JOIN_EXIT_AMPLIFICATION_SIZE = 23;
          /**
           * @dev Calculates due protocol fees originating from accumulated swap fees and yield of non-exempt tokens, pays
           * them by minting BPT, and returns the actual supply and current balances.
           *
           * We also return the current invariant computed using the amplification factor at the last join or exit, which can
           * be useful to skip computations in scenarios where the amplification factor is not changing.
           */
          function _payProtocolFeesBeforeJoinExit(
              uint256[] memory registeredBalances,
              uint256 lastJoinExitAmp,
              uint256 lastPostJoinExitInvariant
          )
              internal
              returns (
                  uint256,
                  uint256[] memory,
                  uint256
              )
          {
              (uint256 virtualSupply, uint256[] memory balances) = _dropBptItemFromBalances(registeredBalances);
              // First, we'll compute what percentage of the Pool the protocol should own due to charging protocol fees on
              // swap fees and yield.
              (
                  uint256 expectedProtocolOwnershipPercentage,
                  uint256 currentInvariantWithLastJoinExitAmp
              ) = _getProtocolPoolOwnershipPercentage(balances, lastJoinExitAmp, lastPostJoinExitInvariant);
              // Now that we know what percentage of the Pool's current value the protocol should own, we can compute how
              // much BPT we need to mint to get to this state. Since we're going to mint BPT for the protocol, the value
              // of each BPT is going to be reduced as all LPs get diluted.
              uint256 protocolFeeAmount = ProtocolFees.bptForPoolOwnershipPercentage(
                  virtualSupply,
                  expectedProtocolOwnershipPercentage
              );
              if (protocolFeeAmount > 0) {
                  _payProtocolFees(protocolFeeAmount);
              }
              // We pay fees before a join or exit to ensure the pool is debt-free. This increases the virtual supply (making
              // it match the actual supply).
              //
              // For this addition to overflow, `totalSupply` would also have already overflowed.
              return (virtualSupply + protocolFeeAmount, balances, currentInvariantWithLastJoinExitAmp);
          }
          function _getProtocolPoolOwnershipPercentage(
              uint256[] memory balances,
              uint256 lastJoinExitAmp,
              uint256 lastPostJoinExitInvariant
          ) internal view returns (uint256, uint256) {
              // We compute three invariants, adjusting the balances of tokens that have rate providers by undoing the current
              // rate adjustment and then applying the old rate. This is equivalent to multiplying by old rate / current rate.
              //
              // In all cases we compute invariants with the last join-exit amplification factor, so that changes to the
              // amplification are not translated into changes to the invariant. Since amplification factor changes are both
              // infrequent and slow, they should have little effect on the pool balances, making this a very good
              // approximation.
              //
              // With this technique we obtain an invariant that does not include yield at all, meaning any growth will be due
              // exclusively to swap fees. We call this the 'swap fee growth invariant'.
              // A second invariant will exclude the yield of exempt tokens, and therefore include both swap fees and
              // non-exempt yield. This is called the 'non exempt growth invariant'.
              // Finally, a third invariant includes the yield of all tokens by using only the current rates. We call this the
              // 'total growth invariant', since it includes both swap fee growth, non-exempt yield growth and exempt yield
              // growth. If the last join-exit amplification equals the current one, this invariant equals the current
              // invariant.
              (
                  uint256 swapFeeGrowthInvariant,
                  uint256 totalNonExemptGrowthInvariant,
                  uint256 totalGrowthInvariant
              ) = _getGrowthInvariants(balances, lastJoinExitAmp, lastPostJoinExitInvariant);
              // By comparing the invariant increase attributable to each source of growth to the total growth invariant,
              // we can calculate how much of the current Pool value originates from that source, and then apply the
              // corresponding protocol fee percentage to that amount.
              // We have two sources of growth: swap fees, and non-exempt yield. As we illustrate graphically below:
              //
              // growth due to swap fees        = (swap fee growth invariant - last post join-exit invariant)
              // growth due to non-exempt yield = (non-exempt growth invariant - swap fee growth invariant)
              //
              // These can be converted to additive percentages by normalizing against the total growth invariant value:
              // growth due to swap fees / total growth invariant = % pool ownership due from swap fees
              // growth due to non-exempt yield / total growth invariant = % pool ownership due from non-exempt yield
              //
              //   ┌───────────────────────┐ ──┐
              //   │  exempt yield         │   │  total growth invariant
              //   ├───────────────────────┤   │ ──┐
              //   │  non-exempt yield     │   │   │  non-exempt growth invariant
              //   ├───────────────────────┤   │   │ ──┐
              //   │  swap fees            │   │   │   │  swap fee growth invariant
              //   ├───────────────────────┤   │   │   │ ──┐
              //   │   original value      │   │   │   │   │  last post join-exit invariant
              //   └───────────────────────┘ ──┘ ──┘ ──┘ ──┘
              //
              // Each invariant should be larger than its precedessor. In case any rounding error results in them being
              // smaller, we adjust the subtraction to equal 0.
              // Note: in the unexpected scenario where the rates of the tokens shrink over time instead of growing (i.e. if
              // the yield is negative), the non-exempt growth invariant might actually be *smaller* than the swap fee growth
              // invariant, and the total growth invariant might be *smaller* than the non-exempt growth invariant. Depending
              // on the order in which swaps, joins/exits and rate changes happen, as well as their relative magnitudes, it is
              // possible for the Pool to either pay more or less protocol fees than it should.
              // This patched version handles these edge cases gracefully, as it 1) forcibly bounds the swap fee growth
              // invariant between the total growth and last post join-exit invariant; 2) enforces "all or nothing" exempt
              // flags, which constrains the non-exempt growth invariant to be equal to either the total growth or swap
              // fee growth invariant.
              //
              // Furthermore, the protocol ownership percentage is hard-coded to zero (so protocol fees will be zero),
              // if the total growth invariant has gone *down* since the last join or exit, which is possible if rates
              // declined. Together, these measures ensure protocol fee amounts will be bound by the non-manipulable
              // swap fee growth, or zero in any pathological situations.
              // If the total invariant decreased or stayed the same, there is no growth to split between swap and yield fees.
              if (totalGrowthInvariant <= lastPostJoinExitInvariant) {
                  return (0, totalGrowthInvariant);
              }
              // By now, the following inequality applies:
              // totalGrowthInvariant >= totalNonExemptGrowthInvariant >= swapFeeGrowthInvariant >= lastPostJoinExitInvariant
              // So these differences are safe to execute; their lower bound is 0 and they will not overflow.
              uint256 swapFeeGrowthInvariantDelta = swapFeeGrowthInvariant - lastPostJoinExitInvariant;
              uint256 nonExemptYieldGrowthInvariantDelta = totalNonExemptGrowthInvariant - swapFeeGrowthInvariant;
              // We can now derive what percentage of the Pool's total value each invariant delta represents by dividing by
              // the total growth invariant. These values, multiplied by the protocol fee percentage for each growth type,
              // represent the percentage of Pool ownership the protocol should have due to each source.
              uint256 protocolSwapFeePercentage = swapFeeGrowthInvariantDelta.divDown(totalGrowthInvariant).mulDown(
                  getProtocolFeePercentageCache(ProtocolFeeType.SWAP)
              );
              uint256 protocolYieldPercentage = nonExemptYieldGrowthInvariantDelta.divDown(totalGrowthInvariant).mulDown(
                  getProtocolFeePercentageCache(ProtocolFeeType.YIELD)
              );
              // These percentages can then be simply added to compute the total protocol Pool ownership percentage.
              // This is naturally bounded above by FixedPoint.ONE so this addition cannot overflow.
              return (protocolSwapFeePercentage + protocolYieldPercentage, totalGrowthInvariant);
          }
          /**
           * @dev Returns total growth invariant and swap / yield invariant approximations.
           * The calculated invariants are bounded such that:
           *
           * - if totalGrowthInvariant <= lastPostJoinExitInvariant, the total value has decreased, so we can skip all
           * other invariant calculations and just return `totalGrowthInvariant` for all. Protocol fees should be zero
           * in this case, so callers using this to compute fees must also check for this, and return zero for the
           * protocol ownership percentage.
           *
           * - Otherwise, totalGrowthInvariant >= totalNonExemptGrowthInvariant >=
           *     swapFeeGrowthInvariant >= lastPostJoinExitInvariant
           * This was previously an assumption, but is now ensured by the logic in this function.
           */
          function _getGrowthInvariants(
              uint256[] memory balances,
              uint256 lastJoinExitAmp,
              uint256 lastPostJoinExitInvariant
          )
              internal
              view
              returns (
                  uint256 swapFeeGrowthInvariant,
                  uint256 totalNonExemptGrowthInvariant,
                  uint256 totalGrowthInvariant
              )
          {
              // Total growth invariant is always calculated with the current (scaled / unadjusted) balances.
              totalGrowthInvariant = StableMath._calculateInvariant(lastJoinExitAmp, balances);
              // If total invariant decreased, calculating the other approximations is unnecessary.
              if (totalGrowthInvariant <= lastPostJoinExitInvariant) {
                  return (totalGrowthInvariant, totalGrowthInvariant, totalGrowthInvariant);
              }
              // Swap fee invariant is calculated with adjusted balances, to discount the yield.
              swapFeeGrowthInvariant = StableMath._calculateInvariant(
                  lastJoinExitAmp,
                  _getAdjustedBalances(balances) // Adjust all token balances with rate providers.
              );
              // The `swapFeeGrowthInvariant` cannot ever be outside the bounds:
              // totalGrowthInvariant >= swapFeeGrowthInvariant >= lastPostJoinExitInvariant
              swapFeeGrowthInvariant = Math.min(totalGrowthInvariant, swapFeeGrowthInvariant); // Set upper bound.
              swapFeeGrowthInvariant = Math.max(lastPostJoinExitInvariant, swapFeeGrowthInvariant); // Set lower bound.
              // The only two accepted possibilities are either all tokens exempt, or none tokens exempt.
              // totalNonExemptGrowthInvariant will either be totalGrowthInvariant or swapFeeGrowthInvariant.
              // At this point,
              // - totalGrowthInvariant > lastPostJoinExitInvariant
              // - totalGrowthInvariant >= swapFeeGrowthInvariant >= lastPostJoinExitInvariant
              // So the complete inequality will apply by the end of this function:
              // totalGrowthInvariant >= totalNonExemptGrowthInvariant >= swapFeeGrowthInvariant >= lastPostJoinExitInvariant
              if (isExemptFromYieldProtocolFee()) {
                  // If no tokens are charged fees on yield, then the non-exempt growth is equal to the swap fee growth - no
                  // yield fees will be collected.
                  totalNonExemptGrowthInvariant = swapFeeGrowthInvariant;
              } else {
                  // If there are no tokens with fee-exempt yield, then the total non-exempt growth will equal the total
                  // growth: all yield growth is non-exempt. There's also no point in adjusting balances, since we
                  // already know none are exempt.
                  totalNonExemptGrowthInvariant = totalGrowthInvariant;
              }
          }
          /**
           * @dev Store the latest invariant based on the adjusted balances after the join or exit, using current rates.
           * Also cache the amp factor, so that the invariant is not affected by amp updates between joins and exits.
           *
           * Pay protocol fees due on any current join or exit swap.
           */
          function _updateInvariantAfterJoinExit(
              uint256 currentAmp,
              uint256[] memory balances,
              uint256 preJoinExitInvariant,
              uint256 preJoinExitSupply,
              uint256 postJoinExitSupply
          ) internal {
              // `_payProtocolFeesBeforeJoinExit` paid protocol fees accumulated between the previous and current
              // join or exit, while this code pays any protocol fees due on the current join or exit.
              // The amp and rates are constant during a single transaction, so it doesn't matter if there
              // is an ongoing amp change, and we can ignore yield.
              // Compute the growth ratio between the pre- and post-join/exit balances.
              // Note that the pre-join/exit invariant is *not* the invariant from the last join,
              // but computed from the balances before this particular join/exit.
              uint256 postJoinExitInvariant = StableMath._calculateInvariant(currentAmp, balances);
              // Compute the portion of the invariant increase due to fees
              uint256 supplyGrowthRatio = postJoinExitSupply.divDown(preJoinExitSupply);
              uint256 feelessInvariant = preJoinExitInvariant.mulDown(supplyGrowthRatio);
              // The postJoinExitInvariant should always be greater than the feelessInvariant (since the invariant and total
              // supply move proportionally outside of fees, which the postJoinInvariant includes and the feelessInvariant
              // does not). However, in the unexpected case in which due to rounding errors this is not true, we simply skip
              // further computation of protocol fees.
              if (postJoinExitInvariant > feelessInvariant) {
                  uint256 invariantDeltaFromFees = postJoinExitInvariant - feelessInvariant;
                  // To convert to a percentage of pool ownership, multiply by the rate,
                  // then normalize against the final invariant
                  uint256 protocolOwnershipPercentage = Math.divDown(
                      Math.mul(invariantDeltaFromFees, getProtocolFeePercentageCache(ProtocolFeeType.SWAP)),
                      postJoinExitInvariant
                  );
                  if (protocolOwnershipPercentage > 0) {
                      uint256 protocolFeeAmount = ProtocolFees.bptForPoolOwnershipPercentage(
                          postJoinExitSupply,
                          protocolOwnershipPercentage
                      );
                      _payProtocolFees(protocolFeeAmount);
                  }
              }
              _updatePostJoinExit(currentAmp, postJoinExitInvariant);
          }
          /**
           * @dev Update the stored values of the amp and final post-join/exit invariant, to reset the basis for protocol
           * swap fees. Also copy the current rates to the old rates, to establish the new protocol yield basis for protocol
           * yield fees.
           */
          function _updatePostJoinExit(uint256 currentAmp, uint256 postJoinExitInvariant) internal {
              _lastJoinExitData =
                  WordCodec.encodeUint(currentAmp, _LAST_JOIN_EXIT_AMPLIFICATION_OFFSET, _LAST_JOIN_EXIT_AMPLIFICATION_SIZE) |
                  WordCodec.encodeUint(
                      postJoinExitInvariant,
                      _LAST_POST_JOIN_EXIT_INVARIANT_OFFSET,
                      _LAST_POST_JOIN_EXIT_INVARIANT_SIZE
                  );
              _updateOldRates();
          }
          /**
           * @notice Return the amplification factor and invariant as of the most recent join or exit (including BPT swaps)
           */
          function getLastJoinExitData()
              public
              view
              returns (uint256 lastJoinExitAmplification, uint256 lastPostJoinExitInvariant)
          {
              bytes32 rawData = _lastJoinExitData;
              lastJoinExitAmplification = rawData.decodeUint(
                  _LAST_JOIN_EXIT_AMPLIFICATION_OFFSET,
                  _LAST_JOIN_EXIT_AMPLIFICATION_SIZE
              );
              lastPostJoinExitInvariant = rawData.decodeUint(
                  _LAST_POST_JOIN_EXIT_INVARIANT_OFFSET,
                  _LAST_POST_JOIN_EXIT_INVARIANT_SIZE
              );
          }
          /**
           * @dev Inheritance rules still require us to override this in the most derived contract, even though
           * it only calls super.
           */
          function _isOwnerOnlyAction(bytes32 actionId)
              internal
              view
              virtual
              override(
                  // Our inheritance pattern creates a small diamond that requires explicitly listing the parents here.
                  // Each parent calls the `super` version, so linearization ensures all implementations are called.
                  BasePool,
                  BasePoolAuthorization,
                  ComposableStablePoolRates
              )
              returns (bool)
          {
              return super._isOwnerOnlyAction(actionId);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-pool-utils/contracts/BasePoolAuthorization.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/helpers/WordCodec.sol";
      import "./StableMath.sol";
      abstract contract StablePoolAmplification is BasePoolAuthorization {
          using WordCodec for bytes32;
          // This contract uses timestamps to slowly update its Amplification parameter over time. These changes must occur
          // over a minimum time period much larger than the blocktime, making timestamp manipulation a non-issue.
          // solhint-disable not-rely-on-time
          // Amplification factor changes must happen over a minimum period of one day, and can at most divide or multiply the
          // current value by 2 every day.
          // WARNING: this only limits *a single* amplification change to have a maximum rate of change of twice the original
          // value daily. It is possible to perform multiple amplification changes in sequence to increase this value more
          // rapidly: for example, by doubling the value every day it can increase by a factor of 8 over three days (2^3).
          uint256 private constant _MIN_UPDATE_TIME = 1 days;
          uint256 private constant _MAX_AMP_UPDATE_DAILY_RATE = 2;
          // The amplification data structure is as follows:
          // [  64 bits |   64 bits  |  64 bits  |   64 bits   ]
          // [ end time | start time | end value | start value ]
          // |MSB                                           LSB|
          uint256 private constant _AMP_START_VALUE_OFFSET = 0;
          uint256 private constant _AMP_END_VALUE_OFFSET = 64;
          uint256 private constant _AMP_START_TIME_OFFSET = 128;
          uint256 private constant _AMP_END_TIME_OFFSET = 192;
          uint256 private constant _AMP_VALUE_BIT_LENGTH = 64;
          uint256 private constant _AMP_TIMESTAMP_BIT_LENGTH = 64;
          bytes32 private _packedAmplificationData;
          event AmpUpdateStarted(uint256 startValue, uint256 endValue, uint256 startTime, uint256 endTime);
          event AmpUpdateStopped(uint256 currentValue);
          constructor(uint256 amplificationParameter) {
              _require(amplificationParameter >= StableMath._MIN_AMP, Errors.MIN_AMP);
              _require(amplificationParameter <= StableMath._MAX_AMP, Errors.MAX_AMP);
              uint256 initialAmp = Math.mul(amplificationParameter, StableMath._AMP_PRECISION);
              _setAmplificationData(initialAmp);
          }
          function getAmplificationParameter()
              external
              view
              returns (
                  uint256 value,
                  bool isUpdating,
                  uint256 precision
              )
          {
              (value, isUpdating) = _getAmplificationParameter();
              precision = StableMath._AMP_PRECISION;
          }
          // Return the current amp value, which will be an interpolation if there is an ongoing amp update.
          // Also return a flag indicating whether there is an ongoing update.
          function _getAmplificationParameter() internal view returns (uint256 value, bool isUpdating) {
              (uint256 startValue, uint256 endValue, uint256 startTime, uint256 endTime) = _getAmplificationData();
              // Note that block.timestamp >= startTime, since startTime is set to the current time when an update starts
              if (block.timestamp < endTime) {
                  isUpdating = true;
                  // We can skip checked arithmetic as:
                  //  - block.timestamp is always larger or equal to startTime
                  //  - endTime is always larger than startTime
                  //  - the value delta is bounded by the largest amplification parameter, which never causes the
                  //    multiplication to overflow.
                  // This also means that the following computation will never revert nor yield invalid results.
                  if (endValue > startValue) {
                      value = startValue + ((endValue - startValue) * (block.timestamp - startTime)) / (endTime - startTime);
                  } else {
                      value = startValue - ((startValue - endValue) * (block.timestamp - startTime)) / (endTime - startTime);
                  }
              } else {
                  isUpdating = false;
                  value = endValue;
              }
          }
          // Unpack and return all amplification-related parameters.
          function _getAmplificationData()
              private
              view
              returns (
                  uint256 startValue,
                  uint256 endValue,
                  uint256 startTime,
                  uint256 endTime
              )
          {
              startValue = _packedAmplificationData.decodeUint(_AMP_START_VALUE_OFFSET, _AMP_VALUE_BIT_LENGTH);
              endValue = _packedAmplificationData.decodeUint(_AMP_END_VALUE_OFFSET, _AMP_VALUE_BIT_LENGTH);
              startTime = _packedAmplificationData.decodeUint(_AMP_START_TIME_OFFSET, _AMP_TIMESTAMP_BIT_LENGTH);
              endTime = _packedAmplificationData.decodeUint(_AMP_END_TIME_OFFSET, _AMP_TIMESTAMP_BIT_LENGTH);
          }
          /**
           * @dev Begin changing the amplification parameter to `rawEndValue` over time. The value will change linearly until
           * `endTime` is reached, when it will be `rawEndValue`.
           *
           * NOTE: Internally, the amplification parameter is represented using higher precision. The values returned by
           * `getAmplificationParameter` have to be corrected to account for this when comparing to `rawEndValue`.
           */
          function startAmplificationParameterUpdate(uint256 rawEndValue, uint256 endTime) external authenticate {
              _require(rawEndValue >= StableMath._MIN_AMP, Errors.MIN_AMP);
              _require(rawEndValue <= StableMath._MAX_AMP, Errors.MAX_AMP);
              uint256 duration = Math.sub(endTime, block.timestamp);
              _require(duration >= _MIN_UPDATE_TIME, Errors.AMP_END_TIME_TOO_CLOSE);
              (uint256 currentValue, bool isUpdating) = _getAmplificationParameter();
              _require(!isUpdating, Errors.AMP_ONGOING_UPDATE);
              uint256 endValue = Math.mul(rawEndValue, StableMath._AMP_PRECISION);
              // daily rate = (endValue / currentValue) / duration * 1 day
              // We perform all multiplications first to not reduce precision, and round the division up as we want to avoid
              // large rates. Note that these are regular integer multiplications and divisions, not fixed point.
              uint256 dailyRate = endValue > currentValue
                  ? Math.divUp(Math.mul(1 days, endValue), Math.mul(currentValue, duration))
                  : Math.divUp(Math.mul(1 days, currentValue), Math.mul(endValue, duration));
              _require(dailyRate <= _MAX_AMP_UPDATE_DAILY_RATE, Errors.AMP_RATE_TOO_HIGH);
              _setAmplificationData(currentValue, endValue, block.timestamp, endTime);
          }
          /**
           * @dev Stops the amplification parameter change process, keeping the current value.
           */
          function stopAmplificationParameterUpdate() external authenticate {
              (uint256 currentValue, bool isUpdating) = _getAmplificationParameter();
              _require(isUpdating, Errors.AMP_NO_ONGOING_UPDATE);
              _setAmplificationData(currentValue);
          }
          function _setAmplificationData(uint256 value) private {
              _storeAmplificationData(value, value, block.timestamp, block.timestamp);
              emit AmpUpdateStopped(value);
          }
          function _setAmplificationData(
              uint256 startValue,
              uint256 endValue,
              uint256 startTime,
              uint256 endTime
          ) private {
              _storeAmplificationData(startValue, endValue, startTime, endTime);
              emit AmpUpdateStarted(startValue, endValue, startTime, endTime);
          }
          function _storeAmplificationData(
              uint256 startValue,
              uint256 endValue,
              uint256 startTime,
              uint256 endTime
          ) private {
              _packedAmplificationData =
                  WordCodec.encodeUint(startValue, _AMP_START_VALUE_OFFSET, _AMP_VALUE_BIT_LENGTH) |
                  WordCodec.encodeUint(endValue, _AMP_END_VALUE_OFFSET, _AMP_VALUE_BIT_LENGTH) |
                  WordCodec.encodeUint(startTime, _AMP_START_TIME_OFFSET, _AMP_TIMESTAMP_BIT_LENGTH) |
                  WordCodec.encodeUint(endTime, _AMP_END_TIME_OFFSET, _AMP_TIMESTAMP_BIT_LENGTH);
          }
          // Permissioned functions
          /**
           * @dev Overrides only owner action to allow setting the cache duration for the token rates
           */
          function _isOwnerOnlyAction(bytes32 actionId) internal view virtual override returns (bool) {
              return
                  (actionId == getActionId(this.startAmplificationParameterUpdate.selector)) ||
                  (actionId == getActionId(this.stopAmplificationParameterUpdate.selector)) ||
                  super._isOwnerOnlyAction(actionId);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-solidity-utils/contracts/math/FixedPoint.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/math/Math.sol";
      // These functions start with an underscore, as if they were part of a contract and not a library. At some point this
      // should be fixed. Additionally, some variables have non mixed case names (e.g. P_D) that relate to the mathematical
      // derivations.
      // solhint-disable private-vars-leading-underscore, var-name-mixedcase
      library StableMath {
          using FixedPoint for uint256;
          uint256 internal constant _MIN_AMP = 1;
          uint256 internal constant _MAX_AMP = 5000;
          uint256 internal constant _AMP_PRECISION = 1e3;
          uint256 internal constant _MAX_STABLE_TOKENS = 5;
          // Note on unchecked arithmetic:
          // This contract performs a large number of additions, subtractions, multiplications and divisions, often inside
          // loops. Since many of these operations are gas-sensitive (as they happen e.g. during a swap), it is important to
          // not make any unnecessary checks. We rely on a set of invariants to avoid having to use checked arithmetic (the
          // Math library), including:
          //  - the number of tokens is bounded by _MAX_STABLE_TOKENS
          //  - the amplification parameter is bounded by _MAX_AMP * _AMP_PRECISION, which fits in 23 bits
          //  - the token balances are bounded by 2^112 (guaranteed by the Vault) times 1e18 (the maximum scaling factor),
          //    which fits in 172 bits
          //
          // This means e.g. we can safely multiply a balance by the amplification parameter without worrying about overflow.
          // About swap fees on joins and exits:
          // Any join or exit that is not perfectly balanced (e.g. all single token joins or exits) is mathematically
          // equivalent to a perfectly balanced join or  exit followed by a series of swaps. Since these swaps would charge
          // swap fees, it follows that (some) joins and exits should as well.
          // On these operations, we split the token amounts in 'taxable' and 'non-taxable' portions, where the 'taxable' part
          // is the one to which swap fees are applied.
          // Computes the invariant given the current balances, using the Newton-Raphson approximation.
          // The amplification parameter equals: A n^(n-1)
          // See: https://github.com/curvefi/curve-contract/blob/b0bbf77f8f93c9c5f4e415bce9cd71f0cdee960e/contracts/pool-templates/base/SwapTemplateBase.vy#L206
          // solhint-disable-previous-line max-line-length
          function _calculateInvariant(uint256 amplificationParameter, uint256[] memory balances)
              internal
              pure
              returns (uint256)
          {
              /**********************************************************************************************
              // invariant                                                                                 //
              // D = invariant                                                  D^(n+1)                    //
              // A = amplification coefficient      A  n^n S + D = A D n^n + -----------                   //
              // S = sum of balances                                             n^n P                     //
              // P = product of balances                                                                   //
              // n = number of tokens                                                                      //
              **********************************************************************************************/
              // Always round down, to match Vyper's arithmetic (which always truncates).
              uint256 sum = 0; // S in the Curve version
              uint256 numTokens = balances.length;
              for (uint256 i = 0; i < numTokens; i++) {
                  sum = sum.add(balances[i]);
              }
              if (sum == 0) {
                  return 0;
              }
              uint256 prevInvariant; // Dprev in the Curve version
              uint256 invariant = sum; // D in the Curve version
              uint256 ampTimesTotal = amplificationParameter * numTokens; // Ann in the Curve version
              for (uint256 i = 0; i < 255; i++) {
                  uint256 D_P = invariant;
                  for (uint256 j = 0; j < numTokens; j++) {
                      // (D_P * invariant) / (balances[j] * numTokens)
                      D_P = Math.divDown(Math.mul(D_P, invariant), Math.mul(balances[j], numTokens));
                  }
                  prevInvariant = invariant;
                  invariant = Math.divDown(
                      Math.mul(
                          // (ampTimesTotal * sum) / AMP_PRECISION + D_P * numTokens
                          (Math.divDown(Math.mul(ampTimesTotal, sum), _AMP_PRECISION).add(Math.mul(D_P, numTokens))),
                          invariant
                      ),
                      // ((ampTimesTotal - _AMP_PRECISION) * invariant) / _AMP_PRECISION + (numTokens + 1) * D_P
                      (
                          Math.divDown(Math.mul((ampTimesTotal - _AMP_PRECISION), invariant), _AMP_PRECISION).add(
                              Math.mul((numTokens + 1), D_P)
                          )
                      )
                  );
                  if (invariant > prevInvariant) {
                      if (invariant - prevInvariant <= 1) {
                          return invariant;
                      }
                  } else if (prevInvariant - invariant <= 1) {
                      return invariant;
                  }
              }
              _revert(Errors.STABLE_INVARIANT_DIDNT_CONVERGE);
          }
          // Computes how many tokens can be taken out of a pool if `tokenAmountIn` are sent, given the current balances.
          // The amplification parameter equals: A n^(n-1)
          function _calcOutGivenIn(
              uint256 amplificationParameter,
              uint256[] memory balances,
              uint256 tokenIndexIn,
              uint256 tokenIndexOut,
              uint256 tokenAmountIn,
              uint256 invariant
          ) internal pure returns (uint256) {
              /**************************************************************************************************************
              // outGivenIn token x for y - polynomial equation to solve                                                   //
              // ay = amount out to calculate                                                                              //
              // by = balance token out                                                                                    //
              // y = by - ay (finalBalanceOut)                                                                             //
              // D = invariant                                               D                     D^(n+1)                 //
              // A = amplification coefficient               y^2 + ( S - ----------  - D) * y -  ------------- = 0         //
              // n = number of tokens                                    (A * n^n)               A * n^2n * P              //
              // S = sum of final balances but y                                                                           //
              // P = product of final balances but y                                                                       //
              **************************************************************************************************************/
              // Amount out, so we round down overall.
              balances[tokenIndexIn] = balances[tokenIndexIn].add(tokenAmountIn);
              uint256 finalBalanceOut = _getTokenBalanceGivenInvariantAndAllOtherBalances(
                  amplificationParameter,
                  balances,
                  invariant,
                  tokenIndexOut
              );
              // No need to use checked arithmetic since `tokenAmountIn` was actually added to the same balance right before
              // calling `_getTokenBalanceGivenInvariantAndAllOtherBalances` which doesn't alter the balances array.
              balances[tokenIndexIn] = balances[tokenIndexIn] - tokenAmountIn;
              return balances[tokenIndexOut].sub(finalBalanceOut).sub(1);
          }
          // Computes how many tokens must be sent to a pool if `tokenAmountOut` are sent given the
          // current balances, using the Newton-Raphson approximation.
          // The amplification parameter equals: A n^(n-1)
          function _calcInGivenOut(
              uint256 amplificationParameter,
              uint256[] memory balances,
              uint256 tokenIndexIn,
              uint256 tokenIndexOut,
              uint256 tokenAmountOut,
              uint256 invariant
          ) internal pure returns (uint256) {
              /**************************************************************************************************************
              // inGivenOut token x for y - polynomial equation to solve                                                   //
              // ax = amount in to calculate                                                                               //
              // bx = balance token in                                                                                     //
              // x = bx + ax (finalBalanceIn)                                                                              //
              // D = invariant                                                D                     D^(n+1)                //
              // A = amplification coefficient               x^2 + ( S - ----------  - D) * x -  ------------- = 0         //
              // n = number of tokens                                     (A * n^n)               A * n^2n * P             //
              // S = sum of final balances but x                                                                           //
              // P = product of final balances but x                                                                       //
              **************************************************************************************************************/
              // Amount in, so we round up overall.
              balances[tokenIndexOut] = balances[tokenIndexOut].sub(tokenAmountOut);
              uint256 finalBalanceIn = _getTokenBalanceGivenInvariantAndAllOtherBalances(
                  amplificationParameter,
                  balances,
                  invariant,
                  tokenIndexIn
              );
              // No need to use checked arithmetic since `tokenAmountOut` was actually subtracted from the same balance right
              // before calling `_getTokenBalanceGivenInvariantAndAllOtherBalances` which doesn't alter the balances array.
              balances[tokenIndexOut] = balances[tokenIndexOut] + tokenAmountOut;
              return finalBalanceIn.sub(balances[tokenIndexIn]).add(1);
          }
          function _calcBptOutGivenExactTokensIn(
              uint256 amp,
              uint256[] memory balances,
              uint256[] memory amountsIn,
              uint256 bptTotalSupply,
              uint256 currentInvariant,
              uint256 swapFeePercentage
          ) internal pure returns (uint256) {
              // BPT out, so we round down overall.
              // First loop calculates the sum of all token balances, which will be used to calculate
              // the current weights of each token, relative to this sum
              uint256 sumBalances = 0;
              for (uint256 i = 0; i < balances.length; i++) {
                  sumBalances = sumBalances.add(balances[i]);
              }
              // Calculate the weighted balance ratio without considering fees
              uint256[] memory balanceRatiosWithFee = new uint256[](amountsIn.length);
              // The weighted sum of token balance ratios with fee
              uint256 invariantRatioWithFees = 0;
              for (uint256 i = 0; i < balances.length; i++) {
                  uint256 currentWeight = balances[i].divDown(sumBalances);
                  balanceRatiosWithFee[i] = balances[i].add(amountsIn[i]).divDown(balances[i]);
                  invariantRatioWithFees = invariantRatioWithFees.add(balanceRatiosWithFee[i].mulDown(currentWeight));
              }
              // Second loop calculates new amounts in, taking into account the fee on the percentage excess
              uint256[] memory newBalances = new uint256[](balances.length);
              for (uint256 i = 0; i < balances.length; i++) {
                  uint256 amountInWithoutFee;
                  // Check if the balance ratio is greater than the ideal ratio to charge fees or not
                  if (balanceRatiosWithFee[i] > invariantRatioWithFees) {
                      uint256 nonTaxableAmount = balances[i].mulDown(invariantRatioWithFees.sub(FixedPoint.ONE));
                      uint256 taxableAmount = amountsIn[i].sub(nonTaxableAmount);
                      // No need to use checked arithmetic for the swap fee, it is guaranteed to be lower than 50%
                      amountInWithoutFee = nonTaxableAmount.add(taxableAmount.mulDown(FixedPoint.ONE - swapFeePercentage));
                  } else {
                      amountInWithoutFee = amountsIn[i];
                  }
                  newBalances[i] = balances[i].add(amountInWithoutFee);
              }
              uint256 newInvariant = _calculateInvariant(amp, newBalances);
              uint256 invariantRatio = newInvariant.divDown(currentInvariant);
              // If the invariant didn't increase for any reason, we simply don't mint BPT
              if (invariantRatio > FixedPoint.ONE) {
                  return bptTotalSupply.mulDown(invariantRatio - FixedPoint.ONE);
              } else {
                  return 0;
              }
          }
          function _calcTokenInGivenExactBptOut(
              uint256 amp,
              uint256[] memory balances,
              uint256 tokenIndex,
              uint256 bptAmountOut,
              uint256 bptTotalSupply,
              uint256 currentInvariant,
              uint256 swapFeePercentage
          ) internal pure returns (uint256) {
              // Token in, so we round up overall.
              uint256 newInvariant = bptTotalSupply.add(bptAmountOut).divUp(bptTotalSupply).mulUp(currentInvariant);
              // Calculate amount in without fee.
              uint256 newBalanceTokenIndex = _getTokenBalanceGivenInvariantAndAllOtherBalances(
                  amp,
                  balances,
                  newInvariant,
                  tokenIndex
              );
              uint256 amountInWithoutFee = newBalanceTokenIndex.sub(balances[tokenIndex]);
              // First calculate the sum of all token balances, which will be used to calculate
              // the current weight of each token
              uint256 sumBalances = 0;
              for (uint256 i = 0; i < balances.length; i++) {
                  sumBalances = sumBalances.add(balances[i]);
              }
              // We can now compute how much extra balance is being deposited and used in virtual swaps, and charge swap fees
              // accordingly.
              uint256 currentWeight = balances[tokenIndex].divDown(sumBalances);
              uint256 taxablePercentage = currentWeight.complement();
              uint256 taxableAmount = amountInWithoutFee.mulUp(taxablePercentage);
              uint256 nonTaxableAmount = amountInWithoutFee.sub(taxableAmount);
              // No need to use checked arithmetic for the swap fee, it is guaranteed to be lower than 50%
              return nonTaxableAmount.add(taxableAmount.divUp(FixedPoint.ONE - swapFeePercentage));
          }
          /*
          Flow of calculations:
          amountsTokenOut -> amountsOutProportional ->
          amountOutPercentageExcess -> amountOutBeforeFee -> newInvariant -> amountBPTIn
          */
          function _calcBptInGivenExactTokensOut(
              uint256 amp,
              uint256[] memory balances,
              uint256[] memory amountsOut,
              uint256 bptTotalSupply,
              uint256 currentInvariant,
              uint256 swapFeePercentage
          ) internal pure returns (uint256) {
              // BPT in, so we round up overall.
              // First loop calculates the sum of all token balances, which will be used to calculate
              // the current weights of each token relative to this sum
              uint256 sumBalances = 0;
              for (uint256 i = 0; i < balances.length; i++) {
                  sumBalances = sumBalances.add(balances[i]);
              }
              // Calculate the weighted balance ratio without considering fees
              uint256[] memory balanceRatiosWithoutFee = new uint256[](amountsOut.length);
              uint256 invariantRatioWithoutFees = 0;
              for (uint256 i = 0; i < balances.length; i++) {
                  uint256 currentWeight = balances[i].divUp(sumBalances);
                  balanceRatiosWithoutFee[i] = balances[i].sub(amountsOut[i]).divUp(balances[i]);
                  invariantRatioWithoutFees = invariantRatioWithoutFees.add(balanceRatiosWithoutFee[i].mulUp(currentWeight));
              }
              // Second loop calculates new amounts in, taking into account the fee on the percentage excess
              uint256[] memory newBalances = new uint256[](balances.length);
              for (uint256 i = 0; i < balances.length; i++) {
                  // Swap fees are typically charged on 'token in', but there is no 'token in' here, so we apply it to
                  // 'token out'. This results in slightly larger price impact.
                  uint256 amountOutWithFee;
                  if (invariantRatioWithoutFees > balanceRatiosWithoutFee[i]) {
                      uint256 nonTaxableAmount = balances[i].mulDown(invariantRatioWithoutFees.complement());
                      uint256 taxableAmount = amountsOut[i].sub(nonTaxableAmount);
                      // No need to use checked arithmetic for the swap fee, it is guaranteed to be lower than 50%
                      amountOutWithFee = nonTaxableAmount.add(taxableAmount.divUp(FixedPoint.ONE - swapFeePercentage));
                  } else {
                      amountOutWithFee = amountsOut[i];
                  }
                  newBalances[i] = balances[i].sub(amountOutWithFee);
              }
              uint256 newInvariant = _calculateInvariant(amp, newBalances);
              uint256 invariantRatio = newInvariant.divDown(currentInvariant);
              // return amountBPTIn
              return bptTotalSupply.mulUp(invariantRatio.complement());
          }
          function _calcTokenOutGivenExactBptIn(
              uint256 amp,
              uint256[] memory balances,
              uint256 tokenIndex,
              uint256 bptAmountIn,
              uint256 bptTotalSupply,
              uint256 currentInvariant,
              uint256 swapFeePercentage
          ) internal pure returns (uint256) {
              // Token out, so we round down overall.
              uint256 newInvariant = bptTotalSupply.sub(bptAmountIn).divUp(bptTotalSupply).mulUp(currentInvariant);
              // Calculate amount out without fee
              uint256 newBalanceTokenIndex = _getTokenBalanceGivenInvariantAndAllOtherBalances(
                  amp,
                  balances,
                  newInvariant,
                  tokenIndex
              );
              uint256 amountOutWithoutFee = balances[tokenIndex].sub(newBalanceTokenIndex);
              // First calculate the sum of all token balances, which will be used to calculate
              // the current weight of each token
              uint256 sumBalances = 0;
              for (uint256 i = 0; i < balances.length; i++) {
                  sumBalances = sumBalances.add(balances[i]);
              }
              // We can now compute how much excess balance is being withdrawn as a result of the virtual swaps, which result
              // in swap fees.
              uint256 currentWeight = balances[tokenIndex].divDown(sumBalances);
              uint256 taxablePercentage = currentWeight.complement();
              // Swap fees are typically charged on 'token in', but there is no 'token in' here, so we apply it
              // to 'token out'. This results in slightly larger price impact. Fees are rounded up.
              uint256 taxableAmount = amountOutWithoutFee.mulUp(taxablePercentage);
              uint256 nonTaxableAmount = amountOutWithoutFee.sub(taxableAmount);
              // No need to use checked arithmetic for the swap fee, it is guaranteed to be lower than 50%
              return nonTaxableAmount.add(taxableAmount.mulDown(FixedPoint.ONE - swapFeePercentage));
          }
          // This function calculates the balance of a given token (tokenIndex)
          // given all the other balances and the invariant
          function _getTokenBalanceGivenInvariantAndAllOtherBalances(
              uint256 amplificationParameter,
              uint256[] memory balances,
              uint256 invariant,
              uint256 tokenIndex
          ) internal pure returns (uint256) {
              // Rounds result up overall
              uint256 ampTimesTotal = amplificationParameter * balances.length;
              uint256 sum = balances[0];
              uint256 P_D = balances[0] * balances.length;
              for (uint256 j = 1; j < balances.length; j++) {
                  P_D = Math.divDown(Math.mul(Math.mul(P_D, balances[j]), balances.length), invariant);
                  sum = sum.add(balances[j]);
              }
              // No need to use safe math, based on the loop above `sum` is greater than or equal to `balances[tokenIndex]`
              sum = sum - balances[tokenIndex];
              uint256 inv2 = Math.mul(invariant, invariant);
              // We remove the balance from c by multiplying it
              uint256 c = Math.mul(
                  Math.mul(Math.divUp(inv2, Math.mul(ampTimesTotal, P_D)), _AMP_PRECISION),
                  balances[tokenIndex]
              );
              uint256 b = sum.add(Math.mul(Math.divDown(invariant, ampTimesTotal), _AMP_PRECISION));
              // We iterate to find the balance
              uint256 prevTokenBalance = 0;
              // We multiply the first iteration outside the loop with the invariant to set the value of the
              // initial approximation.
              uint256 tokenBalance = Math.divUp(inv2.add(c), invariant.add(b));
              for (uint256 i = 0; i < 255; i++) {
                  prevTokenBalance = tokenBalance;
                  tokenBalance = Math.divUp(
                      Math.mul(tokenBalance, tokenBalance).add(c),
                      Math.mul(tokenBalance, 2).add(b).sub(invariant)
                  );
                  if (tokenBalance > prevTokenBalance) {
                      if (tokenBalance - prevTokenBalance <= 1) {
                          return tokenBalance;
                      }
                  } else if (prevTokenBalance - tokenBalance <= 1) {
                      return tokenBalance;
                  }
              }
              _revert(Errors.STABLE_GET_BALANCE_DIDNT_CONVERGE);
          }
          function _computeProportionalAmountsIn(
              uint256[] memory balances,
              uint256 bptAmountOut,
              uint256 totalBPT
          ) internal pure returns (uint256[] memory) {
              /************************************************************************************
              // tokensInForExactBptOut                                                          //
              // (per token)                                                                     //
              // aI = amountIn                   /   bptOut   \\                                  //
              // b = balance           aI = b * | ------------ |                                 //
              // bptOut = bptAmountOut           \\  totalBPT  /                                  //
              // bpt = totalBPT                                                                  //
              ************************************************************************************/
              // Tokens in, so we round up overall.
              uint256 bptRatio = bptAmountOut.divUp(totalBPT);
              uint256[] memory amountsIn = new uint256[](balances.length);
              for (uint256 i = 0; i < balances.length; i++) {
                  amountsIn[i] = balances[i].mulUp(bptRatio);
              }
              return amountsIn;
          }
      }
      // SPDX-License-Identifier: MIT
      // Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
      // documentation files (the “Software”), to deal in the Software without restriction, including without limitation the
      // rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
      // permit persons to whom the Software is furnished to do so, subject to the following conditions:
      // The above copyright notice and this permission notice shall be included in all copies or substantial portions of the
      // Software.
      // THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
      // WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
      // COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
      // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      /* solhint-disable */
      /**
       * @dev Exponentiation and logarithm functions for 18 decimal fixed point numbers (both base and exponent/argument).
       *
       * Exponentiation and logarithm with arbitrary bases (x^y and log_x(y)) are implemented by conversion to natural
       * exponentiation and logarithm (where the base is Euler's number).
       *
       * @author Fernando Martinelli - @fernandomartinelli
       * @author Sergio Yuhjtman - @sergioyuhjtman
       * @author Daniel Fernandez - @dmf7z
       */
      library LogExpMath {
          // All fixed point multiplications and divisions are inlined. This means we need to divide by ONE when multiplying
          // two numbers, and multiply by ONE when dividing them.
          // All arguments and return values are 18 decimal fixed point numbers.
          int256 constant ONE_18 = 1e18;
          // Internally, intermediate values are computed with higher precision as 20 decimal fixed point numbers, and in the
          // case of ln36, 36 decimals.
          int256 constant ONE_20 = 1e20;
          int256 constant ONE_36 = 1e36;
          // The domain of natural exponentiation is bound by the word size and number of decimals used.
          //
          // Because internally the result will be stored using 20 decimals, the largest possible result is
          // (2^255 - 1) / 10^20, which makes the largest exponent ln((2^255 - 1) / 10^20) = 130.700829182905140221.
          // The smallest possible result is 10^(-18), which makes largest negative argument
          // ln(10^(-18)) = -41.446531673892822312.
          // We use 130.0 and -41.0 to have some safety margin.
          int256 constant MAX_NATURAL_EXPONENT = 130e18;
          int256 constant MIN_NATURAL_EXPONENT = -41e18;
          // Bounds for ln_36's argument. Both ln(0.9) and ln(1.1) can be represented with 36 decimal places in a fixed point
          // 256 bit integer.
          int256 constant LN_36_LOWER_BOUND = ONE_18 - 1e17;
          int256 constant LN_36_UPPER_BOUND = ONE_18 + 1e17;
          uint256 constant MILD_EXPONENT_BOUND = 2**254 / uint256(ONE_20);
          // 18 decimal constants
          int256 constant x0 = 128000000000000000000; // 2ˆ7
          int256 constant a0 = 38877084059945950922200000000000000000000000000000000000; // eˆ(x0) (no decimals)
          int256 constant x1 = 64000000000000000000; // 2ˆ6
          int256 constant a1 = 6235149080811616882910000000; // eˆ(x1) (no decimals)
          // 20 decimal constants
          int256 constant x2 = 3200000000000000000000; // 2ˆ5
          int256 constant a2 = 7896296018268069516100000000000000; // eˆ(x2)
          int256 constant x3 = 1600000000000000000000; // 2ˆ4
          int256 constant a3 = 888611052050787263676000000; // eˆ(x3)
          int256 constant x4 = 800000000000000000000; // 2ˆ3
          int256 constant a4 = 298095798704172827474000; // eˆ(x4)
          int256 constant x5 = 400000000000000000000; // 2ˆ2
          int256 constant a5 = 5459815003314423907810; // eˆ(x5)
          int256 constant x6 = 200000000000000000000; // 2ˆ1
          int256 constant a6 = 738905609893065022723; // eˆ(x6)
          int256 constant x7 = 100000000000000000000; // 2ˆ0
          int256 constant a7 = 271828182845904523536; // eˆ(x7)
          int256 constant x8 = 50000000000000000000; // 2ˆ-1
          int256 constant a8 = 164872127070012814685; // eˆ(x8)
          int256 constant x9 = 25000000000000000000; // 2ˆ-2
          int256 constant a9 = 128402541668774148407; // eˆ(x9)
          int256 constant x10 = 12500000000000000000; // 2ˆ-3
          int256 constant a10 = 113314845306682631683; // eˆ(x10)
          int256 constant x11 = 6250000000000000000; // 2ˆ-4
          int256 constant a11 = 106449445891785942956; // eˆ(x11)
          /**
           * @dev Exponentiation (x^y) with unsigned 18 decimal fixed point base and exponent.
           *
           * Reverts if ln(x) * y is smaller than `MIN_NATURAL_EXPONENT`, or larger than `MAX_NATURAL_EXPONENT`.
           */
          function pow(uint256 x, uint256 y) internal pure returns (uint256) {
              if (y == 0) {
                  // We solve the 0^0 indetermination by making it equal one.
                  return uint256(ONE_18);
              }
              if (x == 0) {
                  return 0;
              }
              // Instead of computing x^y directly, we instead rely on the properties of logarithms and exponentiation to
              // arrive at that result. In particular, exp(ln(x)) = x, and ln(x^y) = y * ln(x). This means
              // x^y = exp(y * ln(x)).
              // The ln function takes a signed value, so we need to make sure x fits in the signed 256 bit range.
              _require(x >> 255 == 0, Errors.X_OUT_OF_BOUNDS);
              int256 x_int256 = int256(x);
              // We will compute y * ln(x) in a single step. Depending on the value of x, we can either use ln or ln_36. In
              // both cases, we leave the division by ONE_18 (due to fixed point multiplication) to the end.
              // This prevents y * ln(x) from overflowing, and at the same time guarantees y fits in the signed 256 bit range.
              _require(y < MILD_EXPONENT_BOUND, Errors.Y_OUT_OF_BOUNDS);
              int256 y_int256 = int256(y);
              int256 logx_times_y;
              if (LN_36_LOWER_BOUND < x_int256 && x_int256 < LN_36_UPPER_BOUND) {
                  int256 ln_36_x = _ln_36(x_int256);
                  // ln_36_x has 36 decimal places, so multiplying by y_int256 isn't as straightforward, since we can't just
                  // bring y_int256 to 36 decimal places, as it might overflow. Instead, we perform two 18 decimal
                  // multiplications and add the results: one with the first 18 decimals of ln_36_x, and one with the
                  // (downscaled) last 18 decimals.
                  logx_times_y = ((ln_36_x / ONE_18) * y_int256 + ((ln_36_x % ONE_18) * y_int256) / ONE_18);
              } else {
                  logx_times_y = _ln(x_int256) * y_int256;
              }
              logx_times_y /= ONE_18;
              // Finally, we compute exp(y * ln(x)) to arrive at x^y
              _require(
                  MIN_NATURAL_EXPONENT <= logx_times_y && logx_times_y <= MAX_NATURAL_EXPONENT,
                  Errors.PRODUCT_OUT_OF_BOUNDS
              );
              return uint256(exp(logx_times_y));
          }
          /**
           * @dev Natural exponentiation (e^x) with signed 18 decimal fixed point exponent.
           *
           * Reverts if `x` is smaller than MIN_NATURAL_EXPONENT, or larger than `MAX_NATURAL_EXPONENT`.
           */
          function exp(int256 x) internal pure returns (int256) {
              _require(x >= MIN_NATURAL_EXPONENT && x <= MAX_NATURAL_EXPONENT, Errors.INVALID_EXPONENT);
              if (x < 0) {
                  // We only handle positive exponents: e^(-x) is computed as 1 / e^x. We can safely make x positive since it
                  // fits in the signed 256 bit range (as it is larger than MIN_NATURAL_EXPONENT).
                  // Fixed point division requires multiplying by ONE_18.
                  return ((ONE_18 * ONE_18) / exp(-x));
              }
              // First, we use the fact that e^(x+y) = e^x * e^y to decompose x into a sum of powers of two, which we call x_n,
              // where x_n == 2^(7 - n), and e^x_n = a_n has been precomputed. We choose the first x_n, x0, to equal 2^7
              // because all larger powers are larger than MAX_NATURAL_EXPONENT, and therefore not present in the
              // decomposition.
              // At the end of this process we will have the product of all e^x_n = a_n that apply, and the remainder of this
              // decomposition, which will be lower than the smallest x_n.
              // exp(x) = k_0 * a_0 * k_1 * a_1 * ... + k_n * a_n * exp(remainder), where each k_n equals either 0 or 1.
              // We mutate x by subtracting x_n, making it the remainder of the decomposition.
              // The first two a_n (e^(2^7) and e^(2^6)) are too large if stored as 18 decimal numbers, and could cause
              // intermediate overflows. Instead we store them as plain integers, with 0 decimals.
              // Additionally, x0 + x1 is larger than MAX_NATURAL_EXPONENT, which means they will not both be present in the
              // decomposition.
              // For each x_n, we test if that term is present in the decomposition (if x is larger than it), and if so deduct
              // it and compute the accumulated product.
              int256 firstAN;
              if (x >= x0) {
                  x -= x0;
                  firstAN = a0;
              } else if (x >= x1) {
                  x -= x1;
                  firstAN = a1;
              } else {
                  firstAN = 1; // One with no decimal places
              }
              // We now transform x into a 20 decimal fixed point number, to have enhanced precision when computing the
              // smaller terms.
              x *= 100;
              // `product` is the accumulated product of all a_n (except a0 and a1), which starts at 20 decimal fixed point
              // one. Recall that fixed point multiplication requires dividing by ONE_20.
              int256 product = ONE_20;
              if (x >= x2) {
                  x -= x2;
                  product = (product * a2) / ONE_20;
              }
              if (x >= x3) {
                  x -= x3;
                  product = (product * a3) / ONE_20;
              }
              if (x >= x4) {
                  x -= x4;
                  product = (product * a4) / ONE_20;
              }
              if (x >= x5) {
                  x -= x5;
                  product = (product * a5) / ONE_20;
              }
              if (x >= x6) {
                  x -= x6;
                  product = (product * a6) / ONE_20;
              }
              if (x >= x7) {
                  x -= x7;
                  product = (product * a7) / ONE_20;
              }
              if (x >= x8) {
                  x -= x8;
                  product = (product * a8) / ONE_20;
              }
              if (x >= x9) {
                  x -= x9;
                  product = (product * a9) / ONE_20;
              }
              // x10 and x11 are unnecessary here since we have high enough precision already.
              // Now we need to compute e^x, where x is small (in particular, it is smaller than x9). We use the Taylor series
              // expansion for e^x: 1 + x + (x^2 / 2!) + (x^3 / 3!) + ... + (x^n / n!).
              int256 seriesSum = ONE_20; // The initial one in the sum, with 20 decimal places.
              int256 term; // Each term in the sum, where the nth term is (x^n / n!).
              // The first term is simply x.
              term = x;
              seriesSum += term;
              // Each term (x^n / n!) equals the previous one times x, divided by n. Since x is a fixed point number,
              // multiplying by it requires dividing by ONE_20, but dividing by the non-fixed point n values does not.
              term = ((term * x) / ONE_20) / 2;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 3;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 4;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 5;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 6;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 7;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 8;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 9;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 10;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 11;
              seriesSum += term;
              term = ((term * x) / ONE_20) / 12;
              seriesSum += term;
              // 12 Taylor terms are sufficient for 18 decimal precision.
              // We now have the first a_n (with no decimals), and the product of all other a_n present, and the Taylor
              // approximation of the exponentiation of the remainder (both with 20 decimals). All that remains is to multiply
              // all three (one 20 decimal fixed point multiplication, dividing by ONE_20, and one integer multiplication),
              // and then drop two digits to return an 18 decimal value.
              return (((product * seriesSum) / ONE_20) * firstAN) / 100;
          }
          /**
           * @dev Logarithm (log(arg, base), with signed 18 decimal fixed point base and argument.
           */
          function log(int256 arg, int256 base) internal pure returns (int256) {
              // This performs a simple base change: log(arg, base) = ln(arg) / ln(base).
              // Both logBase and logArg are computed as 36 decimal fixed point numbers, either by using ln_36, or by
              // upscaling.
              int256 logBase;
              if (LN_36_LOWER_BOUND < base && base < LN_36_UPPER_BOUND) {
                  logBase = _ln_36(base);
              } else {
                  logBase = _ln(base) * ONE_18;
              }
              int256 logArg;
              if (LN_36_LOWER_BOUND < arg && arg < LN_36_UPPER_BOUND) {
                  logArg = _ln_36(arg);
              } else {
                  logArg = _ln(arg) * ONE_18;
              }
              // When dividing, we multiply by ONE_18 to arrive at a result with 18 decimal places
              return (logArg * ONE_18) / logBase;
          }
          /**
           * @dev Natural logarithm (ln(a)) with signed 18 decimal fixed point argument.
           */
          function ln(int256 a) internal pure returns (int256) {
              // The real natural logarithm is not defined for negative numbers or zero.
              _require(a > 0, Errors.OUT_OF_BOUNDS);
              if (LN_36_LOWER_BOUND < a && a < LN_36_UPPER_BOUND) {
                  return _ln_36(a) / ONE_18;
              } else {
                  return _ln(a);
              }
          }
          /**
           * @dev Internal natural logarithm (ln(a)) with signed 18 decimal fixed point argument.
           */
          function _ln(int256 a) private pure returns (int256) {
              if (a < ONE_18) {
                  // Since ln(a^k) = k * ln(a), we can compute ln(a) as ln(a) = ln((1/a)^(-1)) = - ln((1/a)). If a is less
                  // than one, 1/a will be greater than one, and this if statement will not be entered in the recursive call.
                  // Fixed point division requires multiplying by ONE_18.
                  return (-_ln((ONE_18 * ONE_18) / a));
              }
              // First, we use the fact that ln^(a * b) = ln(a) + ln(b) to decompose ln(a) into a sum of powers of two, which
              // we call x_n, where x_n == 2^(7 - n), which are the natural logarithm of precomputed quantities a_n (that is,
              // ln(a_n) = x_n). We choose the first x_n, x0, to equal 2^7 because the exponential of all larger powers cannot
              // be represented as 18 fixed point decimal numbers in 256 bits, and are therefore larger than a.
              // At the end of this process we will have the sum of all x_n = ln(a_n) that apply, and the remainder of this
              // decomposition, which will be lower than the smallest a_n.
              // ln(a) = k_0 * x_0 + k_1 * x_1 + ... + k_n * x_n + ln(remainder), where each k_n equals either 0 or 1.
              // We mutate a by subtracting a_n, making it the remainder of the decomposition.
              // For reasons related to how `exp` works, the first two a_n (e^(2^7) and e^(2^6)) are not stored as fixed point
              // numbers with 18 decimals, but instead as plain integers with 0 decimals, so we need to multiply them by
              // ONE_18 to convert them to fixed point.
              // For each a_n, we test if that term is present in the decomposition (if a is larger than it), and if so divide
              // by it and compute the accumulated sum.
              int256 sum = 0;
              if (a >= a0 * ONE_18) {
                  a /= a0; // Integer, not fixed point division
                  sum += x0;
              }
              if (a >= a1 * ONE_18) {
                  a /= a1; // Integer, not fixed point division
                  sum += x1;
              }
              // All other a_n and x_n are stored as 20 digit fixed point numbers, so we convert the sum and a to this format.
              sum *= 100;
              a *= 100;
              // Because further a_n are  20 digit fixed point numbers, we multiply by ONE_20 when dividing by them.
              if (a >= a2) {
                  a = (a * ONE_20) / a2;
                  sum += x2;
              }
              if (a >= a3) {
                  a = (a * ONE_20) / a3;
                  sum += x3;
              }
              if (a >= a4) {
                  a = (a * ONE_20) / a4;
                  sum += x4;
              }
              if (a >= a5) {
                  a = (a * ONE_20) / a5;
                  sum += x5;
              }
              if (a >= a6) {
                  a = (a * ONE_20) / a6;
                  sum += x6;
              }
              if (a >= a7) {
                  a = (a * ONE_20) / a7;
                  sum += x7;
              }
              if (a >= a8) {
                  a = (a * ONE_20) / a8;
                  sum += x8;
              }
              if (a >= a9) {
                  a = (a * ONE_20) / a9;
                  sum += x9;
              }
              if (a >= a10) {
                  a = (a * ONE_20) / a10;
                  sum += x10;
              }
              if (a >= a11) {
                  a = (a * ONE_20) / a11;
                  sum += x11;
              }
              // a is now a small number (smaller than a_11, which roughly equals 1.06). This means we can use a Taylor series
              // that converges rapidly for values of `a` close to one - the same one used in ln_36.
              // Let z = (a - 1) / (a + 1).
              // ln(a) = 2 * (z + z^3 / 3 + z^5 / 5 + z^7 / 7 + ... + z^(2 * n + 1) / (2 * n + 1))
              // Recall that 20 digit fixed point division requires multiplying by ONE_20, and multiplication requires
              // division by ONE_20.
              int256 z = ((a - ONE_20) * ONE_20) / (a + ONE_20);
              int256 z_squared = (z * z) / ONE_20;
              // num is the numerator of the series: the z^(2 * n + 1) term
              int256 num = z;
              // seriesSum holds the accumulated sum of each term in the series, starting with the initial z
              int256 seriesSum = num;
              // In each step, the numerator is multiplied by z^2
              num = (num * z_squared) / ONE_20;
              seriesSum += num / 3;
              num = (num * z_squared) / ONE_20;
              seriesSum += num / 5;
              num = (num * z_squared) / ONE_20;
              seriesSum += num / 7;
              num = (num * z_squared) / ONE_20;
              seriesSum += num / 9;
              num = (num * z_squared) / ONE_20;
              seriesSum += num / 11;
              // 6 Taylor terms are sufficient for 36 decimal precision.
              // Finally, we multiply by 2 (non fixed point) to compute ln(remainder)
              seriesSum *= 2;
              // We now have the sum of all x_n present, and the Taylor approximation of the logarithm of the remainder (both
              // with 20 decimals). All that remains is to sum these two, and then drop two digits to return a 18 decimal
              // value.
              return (sum + seriesSum) / 100;
          }
          /**
           * @dev Intrnal high precision (36 decimal places) natural logarithm (ln(x)) with signed 18 decimal fixed point argument,
           * for x close to one.
           *
           * Should only be used if x is between LN_36_LOWER_BOUND and LN_36_UPPER_BOUND.
           */
          function _ln_36(int256 x) private pure returns (int256) {
              // Since ln(1) = 0, a value of x close to one will yield a very small result, which makes using 36 digits
              // worthwhile.
              // First, we transform x to a 36 digit fixed point value.
              x *= ONE_18;
              // We will use the following Taylor expansion, which converges very rapidly. Let z = (x - 1) / (x + 1).
              // ln(x) = 2 * (z + z^3 / 3 + z^5 / 5 + z^7 / 7 + ... + z^(2 * n + 1) / (2 * n + 1))
              // Recall that 36 digit fixed point division requires multiplying by ONE_36, and multiplication requires
              // division by ONE_36.
              int256 z = ((x - ONE_36) * ONE_36) / (x + ONE_36);
              int256 z_squared = (z * z) / ONE_36;
              // num is the numerator of the series: the z^(2 * n + 1) term
              int256 num = z;
              // seriesSum holds the accumulated sum of each term in the series, starting with the initial z
              int256 seriesSum = num;
              // In each step, the numerator is multiplied by z^2
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 3;
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 5;
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 7;
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 9;
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 11;
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 13;
              num = (num * z_squared) / ONE_36;
              seriesSum += num / 15;
              // 8 Taylor terms are sufficient for 36 decimal precision.
              // All that remains is multiplying by 2 (non fixed point).
              return seriesSum * 2;
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "./IBasePool.sol";
      /**
       * @dev IPools with the General specialization setting should implement this interface.
       *
       * This is called by the Vault when a user calls `IVault.swap` or `IVault.batchSwap` to swap with this Pool.
       * Returns the number of tokens the Pool will grant to the user in a 'given in' swap, or that the user will
       * grant to the pool in a 'given out' swap.
       *
       * This can often be implemented by a `view` function, since many pricing algorithms don't need to track state
       * changes in swaps. However, contracts implementing this in non-view functions should check that the caller is
       * indeed the Vault.
       */
      interface IGeneralPool is IBasePool {
          function onSwap(
              SwapRequest memory swapRequest,
              uint256[] memory balances,
              uint256 indexIn,
              uint256 indexOut
          ) external returns (uint256 amount);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "@balancer-labs/v2-interfaces/contracts/pool-utils/IAssetManager.sol";
      import "@balancer-labs/v2-interfaces/contracts/pool-utils/IControlledPool.sol";
      import "@balancer-labs/v2-interfaces/contracts/vault/IVault.sol";
      import "@balancer-labs/v2-interfaces/contracts/vault/IBasePool.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/helpers/InputHelpers.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/helpers/WordCodec.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/helpers/TemporarilyPausable.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/openzeppelin/ERC20.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/math/FixedPoint.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/math/Math.sol";
      import "./BalancerPoolToken.sol";
      import "./BasePoolAuthorization.sol";
      import "./RecoveryMode.sol";
      // solhint-disable max-states-count
      /**
       * @notice Reference implementation for the base layer of a Pool contract.
       * @dev Reference implementation for the base layer of a Pool contract that manages a single Pool with optional
       * Asset Managers, an admin-controlled swap fee percentage, and an emergency pause mechanism.
       *
       * This Pool pays protocol fees by minting BPT directly to the ProtocolFeeCollector instead of using the
       * `dueProtocolFees` return value. This results in the underlying tokens continuing to provide liquidity
       * for traders, while still keeping gas usage to a minimum since only a single token (the BPT) is transferred.
       *
       * Note that neither swap fees nor the pause mechanism are used by this contract. They are passed through so that
       * derived contracts can use them via the `_addSwapFeeAmount` and `_subtractSwapFeeAmount` functions, and the
       * `whenNotPaused` modifier.
       *
       * No admin permissions are checked here: instead, this contract delegates that to the Vault's own Authorizer.
       *
       * Because this contract doesn't implement the swap hooks, derived contracts should generally inherit from
       * BaseGeneralPool or BaseMinimalSwapInfoPool. Otherwise, subclasses must inherit from the corresponding interfaces
       * and implement the swap callbacks themselves.
       */
      abstract contract BasePool is
          IBasePool,
          IControlledPool,
          BasePoolAuthorization,
          BalancerPoolToken,
          TemporarilyPausable,
          RecoveryMode
      {
          using WordCodec for bytes32;
          using FixedPoint for uint256;
          using BasePoolUserData for bytes;
          uint256 private constant _MIN_TOKENS = 2;
          uint256 private constant _DEFAULT_MINIMUM_BPT = 1e6;
          // 1e18 corresponds to 1.0, or a 100% fee
          uint256 private constant _MIN_SWAP_FEE_PERCENTAGE = 1e12; // 0.0001%
          uint256 private constant _MAX_SWAP_FEE_PERCENTAGE = 1e17; // 10% - this fits in 64 bits
          // `_miscData` is a storage slot that can be used to store unrelated pieces of information. All pools store the
          // recovery mode flag and swap fee percentage, but `miscData` can be extended to store more pieces of information.
          // The most signficant bit is reserved for the recovery mode flag, and the swap fee percentage is stored in
          // the next most significant 63 bits, leaving the remaining 192 bits free to store any other information derived
          // pools might need.
          //
          // This slot is preferred for gas-sensitive operations as it is read in all joins, swaps and exits,
          // and therefore warm.
          // [ recovery | swap  fee | available ]
          // [   1 bit  |  63 bits  |  192 bits ]
          // [ MSB                          LSB ]
          bytes32 private _miscData;
          uint256 private constant _SWAP_FEE_PERCENTAGE_OFFSET = 192;
          uint256 private constant _RECOVERY_MODE_BIT_OFFSET = 255;
          // A fee can never be larger than FixedPoint.ONE, which fits in 60 bits, so 63 is more than enough.
          uint256 private constant _SWAP_FEE_PERCENTAGE_BIT_LENGTH = 63;
          bytes32 private immutable _poolId;
          // Note that this value is immutable in the Vault, so we can make it immutable here and save gas
          IProtocolFeesCollector private immutable _protocolFeesCollector;
          event SwapFeePercentageChanged(uint256 swapFeePercentage);
          constructor(
              IVault vault,
              IVault.PoolSpecialization specialization,
              string memory name,
              string memory symbol,
              IERC20[] memory tokens,
              address[] memory assetManagers,
              uint256 swapFeePercentage,
              uint256 pauseWindowDuration,
              uint256 bufferPeriodDuration,
              address owner
          )
              // Base Pools are expected to be deployed using factories. By using the factory address as the action
              // disambiguator, we make all Pools deployed by the same factory share action identifiers. This allows for
              // simpler management of permissions (such as being able to manage granting the 'set fee percentage' action in
              // any Pool created by the same factory), while still making action identifiers unique among different factories
              // if the selectors match, preventing accidental errors.
              Authentication(bytes32(uint256(msg.sender)))
              BalancerPoolToken(name, symbol, vault)
              BasePoolAuthorization(owner)
              TemporarilyPausable(pauseWindowDuration, bufferPeriodDuration)
          {
              _require(tokens.length >= _MIN_TOKENS, Errors.MIN_TOKENS);
              _require(tokens.length <= _getMaxTokens(), Errors.MAX_TOKENS);
              // The Vault only requires the token list to be ordered for the Two Token Pools specialization. However,
              // to make the developer experience consistent, we are requiring this condition for all the native pools.
              // Also, since these Pools will register tokens only once, we can ensure the Pool tokens will follow the same
              // order. We rely on this property to make Pools simpler to write, as it lets us assume that the
              // order of token-specific parameters (such as token weights) will not change.
              InputHelpers.ensureArrayIsSorted(tokens);
              _setSwapFeePercentage(swapFeePercentage);
              bytes32 poolId = vault.registerPool(specialization);
              vault.registerTokens(poolId, tokens, assetManagers);
              // Set immutable state variables - these cannot be read from during construction
              _poolId = poolId;
              _protocolFeesCollector = vault.getProtocolFeesCollector();
          }
          // Getters / Setters
          /**
           * @notice Return the pool id.
           */
          function getPoolId() public view override returns (bytes32) {
              return _poolId;
          }
          function _getTotalTokens() internal view virtual returns (uint256);
          function _getMaxTokens() internal pure virtual returns (uint256);
          /**
           * @dev Returns the minimum BPT supply. This amount is minted to the zero address during initialization, effectively
           * locking it.
           *
           * This is useful to make sure Pool initialization happens only once, but derived Pools can change this value (even
           * to zero) by overriding this function.
           */
          function _getMinimumBpt() internal pure virtual returns (uint256) {
              return _DEFAULT_MINIMUM_BPT;
          }
          /**
           * @notice Return the current value of the swap fee percentage.
           * @dev This is stored in `_miscData`.
           */
          function getSwapFeePercentage() public view virtual override returns (uint256) {
              return _miscData.decodeUint(_SWAP_FEE_PERCENTAGE_OFFSET, _SWAP_FEE_PERCENTAGE_BIT_LENGTH);
          }
          /**
           * @notice Return the ProtocolFeesCollector contract.
           * @dev This is immutable, and retrieved from the Vault on construction. (It is also immutable in the Vault.)
           */
          function getProtocolFeesCollector() public view returns (IProtocolFeesCollector) {
              return _protocolFeesCollector;
          }
          /**
           * @notice Set the swap fee percentage.
           * @dev This is a permissioned function, and disabled if the pool is paused. The swap fee must be within the
           * bounds set by MIN_SWAP_FEE_PERCENTAGE/MAX_SWAP_FEE_PERCENTAGE. Emits the SwapFeePercentageChanged event.
           */
          function setSwapFeePercentage(uint256 swapFeePercentage) public virtual override authenticate whenNotPaused {
              _setSwapFeePercentage(swapFeePercentage);
          }
          function _setSwapFeePercentage(uint256 swapFeePercentage) internal virtual {
              _require(swapFeePercentage >= _getMinSwapFeePercentage(), Errors.MIN_SWAP_FEE_PERCENTAGE);
              _require(swapFeePercentage <= _getMaxSwapFeePercentage(), Errors.MAX_SWAP_FEE_PERCENTAGE);
              _miscData = _miscData.insertUint(
                  swapFeePercentage,
                  _SWAP_FEE_PERCENTAGE_OFFSET,
                  _SWAP_FEE_PERCENTAGE_BIT_LENGTH
              );
              emit SwapFeePercentageChanged(swapFeePercentage);
          }
          function _getMinSwapFeePercentage() internal pure virtual returns (uint256) {
              return _MIN_SWAP_FEE_PERCENTAGE;
          }
          function _getMaxSwapFeePercentage() internal pure virtual returns (uint256) {
              return _MAX_SWAP_FEE_PERCENTAGE;
          }
          /**
           * @notice Returns whether the pool is in Recovery Mode.
           */
          function inRecoveryMode() public view override returns (bool) {
              return _miscData.decodeBool(_RECOVERY_MODE_BIT_OFFSET);
          }
          /**
           * @dev Sets the recoveryMode state, and emits the corresponding event.
           */
          function _setRecoveryMode(bool enabled) internal virtual override {
              _miscData = _miscData.insertBool(enabled, _RECOVERY_MODE_BIT_OFFSET);
              emit RecoveryModeStateChanged(enabled);
              // Some pools need to update their state when leaving recovery mode to ensure proper functioning of the Pool.
              // We do not allow an `_onEnableRecoveryMode()` hook as this may jeopardize the ability to enable Recovery mode.
              if (!enabled) _onDisableRecoveryMode();
          }
          /**
           * @dev Performs any necessary actions on the disabling of Recovery Mode.
           * This is usually to reset any fee collection mechanisms to ensure that they operate correctly going forward.
           */
          function _onDisableRecoveryMode() internal virtual {}
          /**
           * @notice Set the asset manager parameters for the given token.
           * @dev This is a permissioned function, unavailable when the pool is paused.
           * The details of the configuration data are set by each Asset Manager. (For an example, see
           * `RewardsAssetManager`.)
           */
          function setAssetManagerPoolConfig(IERC20 token, bytes memory poolConfig)
              public
              virtual
              override
              authenticate
              whenNotPaused
          {
              _setAssetManagerPoolConfig(token, poolConfig);
          }
          function _setAssetManagerPoolConfig(IERC20 token, bytes memory poolConfig) private {
              bytes32 poolId = getPoolId();
              (, , , address assetManager) = getVault().getPoolTokenInfo(poolId, token);
              IAssetManager(assetManager).setConfig(poolId, poolConfig);
          }
          /**
           * @notice Pause the pool: an emergency action which disables all pool functions.
           * @dev This is a permissioned function that will only work during the Pause Window set during pool factory
           * deployment (see `TemporarilyPausable`).
           */
          function pause() external authenticate {
              _setPaused(true);
          }
          /**
           * @notice Reverse a `pause` operation, and restore a pool to normal functionality.
           * @dev This is a permissioned function that will only work on a paused pool within the Buffer Period set during
           * pool factory deployment (see `TemporarilyPausable`). Note that any paused pools will automatically unpause
           * after the Buffer Period expires.
           */
          function unpause() external authenticate {
              _setPaused(false);
          }
          function _isOwnerOnlyAction(bytes32 actionId) internal view virtual override returns (bool) {
              return
                  (actionId == getActionId(this.setSwapFeePercentage.selector)) ||
                  (actionId == getActionId(this.setAssetManagerPoolConfig.selector)) ||
                  super._isOwnerOnlyAction(actionId);
          }
          function _getMiscData() internal view returns (bytes32) {
              return _miscData;
          }
          /**
           * @dev Inserts data into the least-significant 192 bits of the misc data storage slot.
           * Note that the remaining 64 bits are used for the swap fee percentage and cannot be overloaded.
           */
          function _setMiscData(bytes32 newData) internal {
              _miscData = _miscData.insertBits192(newData, 0);
          }
          // Join / Exit Hooks
          modifier onlyVault(bytes32 poolId) {
              _require(msg.sender == address(getVault()), Errors.CALLER_NOT_VAULT);
              _require(poolId == getPoolId(), Errors.INVALID_POOL_ID);
              _;
          }
          /**
           * @notice Vault hook for adding liquidity to a pool (including the first time, "initializing" the pool).
           * @dev This function can only be called from the Vault, from `joinPool`.
           */
          function onJoinPool(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory balances,
              uint256 lastChangeBlock,
              uint256 protocolSwapFeePercentage,
              bytes memory userData
          ) external override onlyVault(poolId) returns (uint256[] memory, uint256[] memory) {
              _beforeSwapJoinExit();
              uint256[] memory scalingFactors = _scalingFactors();
              if (totalSupply() == 0) {
                  (uint256 bptAmountOut, uint256[] memory amountsIn) = _onInitializePool(
                      poolId,
                      sender,
                      recipient,
                      scalingFactors,
                      userData
                  );
                  // On initialization, we lock _getMinimumBpt() by minting it for the zero address. This BPT acts as a
                  // minimum as it will never be burned, which reduces potential issues with rounding, and also prevents the
                  // Pool from ever being fully drained.
                  _require(bptAmountOut >= _getMinimumBpt(), Errors.MINIMUM_BPT);
                  _mintPoolTokens(address(0), _getMinimumBpt());
                  _mintPoolTokens(recipient, bptAmountOut - _getMinimumBpt());
                  // amountsIn are amounts entering the Pool, so we round up.
                  _downscaleUpArray(amountsIn, scalingFactors);
                  return (amountsIn, new uint256[](balances.length));
              } else {
                  _upscaleArray(balances, scalingFactors);
                  (uint256 bptAmountOut, uint256[] memory amountsIn) = _onJoinPool(
                      poolId,
                      sender,
                      recipient,
                      balances,
                      lastChangeBlock,
                      inRecoveryMode() ? 0 : protocolSwapFeePercentage, // Protocol fees are disabled while in recovery mode
                      scalingFactors,
                      userData
                  );
                  // Note we no longer use `balances` after calling `_onJoinPool`, which may mutate it.
                  _mintPoolTokens(recipient, bptAmountOut);
                  // amountsIn are amounts entering the Pool, so we round up.
                  _downscaleUpArray(amountsIn, scalingFactors);
                  // This Pool ignores the `dueProtocolFees` return value, so we simply return a zeroed-out array.
                  return (amountsIn, new uint256[](balances.length));
              }
          }
          /**
           * @notice Vault hook for removing liquidity from a pool.
           * @dev This function can only be called from the Vault, from `exitPool`.
           */
          function onExitPool(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory balances,
              uint256 lastChangeBlock,
              uint256 protocolSwapFeePercentage,
              bytes memory userData
          ) external override onlyVault(poolId) returns (uint256[] memory, uint256[] memory) {
              uint256[] memory amountsOut;
              uint256 bptAmountIn;
              // When a user calls `exitPool`, this is the first point of entry from the Vault.
              // We first check whether this is a Recovery Mode exit - if so, we proceed using this special lightweight exit
              // mechanism which avoids computing any complex values, interacting with external contracts, etc., and generally
              // should always work, even if the Pool's mathematics or a dependency break down.
              if (userData.isRecoveryModeExitKind()) {
                  // This exit kind is only available in Recovery Mode.
                  _ensureInRecoveryMode();
                  // Note that we don't upscale balances nor downscale amountsOut - we don't care about scaling factors during
                  // a recovery mode exit.
                  (bptAmountIn, amountsOut) = _doRecoveryModeExit(balances, totalSupply(), userData);
              } else {
                  // Note that we only call this if we're not in a recovery mode exit.
                  _beforeSwapJoinExit();
                  uint256[] memory scalingFactors = _scalingFactors();
                  _upscaleArray(balances, scalingFactors);
                  (bptAmountIn, amountsOut) = _onExitPool(
                      poolId,
                      sender,
                      recipient,
                      balances,
                      lastChangeBlock,
                      inRecoveryMode() ? 0 : protocolSwapFeePercentage, // Protocol fees are disabled while in recovery mode
                      scalingFactors,
                      userData
                  );
                  // amountsOut are amounts exiting the Pool, so we round down.
                  _downscaleDownArray(amountsOut, scalingFactors);
              }
              // Note we no longer use `balances` after calling `_onExitPool`, which may mutate it.
              _burnPoolTokens(sender, bptAmountIn);
              // This Pool ignores the `dueProtocolFees` return value, so we simply return a zeroed-out array.
              return (amountsOut, new uint256[](balances.length));
          }
          // Query functions
          /**
           * @notice "Dry run" `onJoinPool`.
           * @dev Returns the amount of BPT that would be granted to `recipient` if the `onJoinPool` hook were called by the
           * Vault with the same arguments, along with the number of tokens `sender` would have to supply.
           *
           * This function is not meant to be called directly, but rather from a helper contract that fetches current Vault
           * data, such as the protocol swap fee percentage and Pool balances.
           *
           * Like `IVault.queryBatchSwap`, this function is not view due to internal implementation details: the caller must
           * explicitly use eth_call instead of eth_sendTransaction.
           */
          function queryJoin(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory balances,
              uint256 lastChangeBlock,
              uint256 protocolSwapFeePercentage,
              bytes memory userData
          ) external override returns (uint256 bptOut, uint256[] memory amountsIn) {
              InputHelpers.ensureInputLengthMatch(balances.length, _getTotalTokens());
              _queryAction(
                  poolId,
                  sender,
                  recipient,
                  balances,
                  lastChangeBlock,
                  protocolSwapFeePercentage,
                  userData,
                  _onJoinPool,
                  _downscaleUpArray
              );
              // The `return` opcode is executed directly inside `_queryAction`, so execution never reaches this statement,
              // and we don't need to return anything here - it just silences compiler warnings.
              return (bptOut, amountsIn);
          }
          /**
           * @notice "Dry run" `onExitPool`.
           * @dev Returns the amount of BPT that would be burned from `sender` if the `onExitPool` hook were called by the
           * Vault with the same arguments, along with the number of tokens `recipient` would receive.
           *
           * This function is not meant to be called directly, but rather from a helper contract that fetches current Vault
           * data, such as the protocol swap fee percentage and Pool balances.
           *
           * Like `IVault.queryBatchSwap`, this function is not view due to internal implementation details: the caller must
           * explicitly use eth_call instead of eth_sendTransaction.
           */
          function queryExit(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory balances,
              uint256 lastChangeBlock,
              uint256 protocolSwapFeePercentage,
              bytes memory userData
          ) external override returns (uint256 bptIn, uint256[] memory amountsOut) {
              InputHelpers.ensureInputLengthMatch(balances.length, _getTotalTokens());
              _queryAction(
                  poolId,
                  sender,
                  recipient,
                  balances,
                  lastChangeBlock,
                  protocolSwapFeePercentage,
                  userData,
                  _onExitPool,
                  _downscaleDownArray
              );
              // The `return` opcode is executed directly inside `_queryAction`, so execution never reaches this statement,
              // and we don't need to return anything here - it just silences compiler warnings.
              return (bptIn, amountsOut);
          }
          // Internal hooks to be overridden by derived contracts - all token amounts (except BPT) in these interfaces are
          // upscaled.
          /**
           * @dev Called when the Pool is joined for the first time; that is, when the BPT total supply is zero.
           *
           * Returns the amount of BPT to mint, and the token amounts the Pool will receive in return.
           *
           * Minted BPT will be sent to `recipient`, except for _getMinimumBpt(), which will be deducted from this amount and
           * sent to the zero address instead. This will cause that BPT to remain forever locked there, preventing total BTP
           * from ever dropping below that value, and ensuring `_onInitializePool` can only be called once in the entire
           * Pool's lifetime.
           *
           * The tokens granted to the Pool will be transferred from `sender`. These amounts are considered upscaled and will
           * be downscaled (rounding up) before being returned to the Vault.
           */
          function _onInitializePool(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory scalingFactors,
              bytes memory userData
          ) internal virtual returns (uint256 bptAmountOut, uint256[] memory amountsIn);
          /**
           * @dev Called whenever the Pool is joined after the first initialization join (see `_onInitializePool`).
           *
           * Returns the amount of BPT to mint, the token amounts that the Pool will receive in return, and the number of
           * tokens to pay in protocol swap fees.
           *
           * Implementations of this function might choose to mutate the `balances` array to save gas (e.g. when
           * performing intermediate calculations, such as subtraction of due protocol fees). This can be done safely.
           *
           * Minted BPT will be sent to `recipient`.
           *
           * The tokens granted to the Pool will be transferred from `sender`. These amounts are considered upscaled and will
           * be downscaled (rounding up) before being returned to the Vault.
           *
           * Due protocol swap fees will be taken from the Pool's balance in the Vault (see `IBasePool.onJoinPool`). These
           * amounts are considered upscaled and will be downscaled (rounding down) before being returned to the Vault.
           */
          function _onJoinPool(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory balances,
              uint256 lastChangeBlock,
              uint256 protocolSwapFeePercentage,
              uint256[] memory scalingFactors,
              bytes memory userData
          ) internal virtual returns (uint256 bptAmountOut, uint256[] memory amountsIn);
          /**
           * @dev Called whenever the Pool is exited.
           *
           * Returns the amount of BPT to burn, the token amounts for each Pool token that the Pool will grant in return, and
           * the number of tokens to pay in protocol swap fees.
           *
           * Implementations of this function might choose to mutate the `balances` array to save gas (e.g. when
           * performing intermediate calculations, such as subtraction of due protocol fees). This can be done safely.
           *
           * BPT will be burnt from `sender`.
           *
           * The Pool will grant tokens to `recipient`. These amounts are considered upscaled and will be downscaled
           * (rounding down) before being returned to the Vault.
           *
           * Due protocol swap fees will be taken from the Pool's balance in the Vault (see `IBasePool.onExitPool`). These
           * amounts are considered upscaled and will be downscaled (rounding down) before being returned to the Vault.
           */
          function _onExitPool(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory balances,
              uint256 lastChangeBlock,
              uint256 protocolSwapFeePercentage,
              uint256[] memory scalingFactors,
              bytes memory userData
          ) internal virtual returns (uint256 bptAmountIn, uint256[] memory amountsOut);
          /**
           * @dev Called at the very beginning of swaps, joins and exits, even before the scaling factors are read. Derived
           * contracts can extend this implementation to perform any state-changing operations they might need (including e.g.
           * updating the scaling factors),
           *
           * The only scenario in which this function is not called is during a recovery mode exit. This makes it safe to
           * perform non-trivial computations or interact with external dependencies here, as recovery mode will not be
           * affected.
           *
           * Since this contract does not implement swaps, derived contracts must also make sure this function is called on
           * swap handlers.
           */
          function _beforeSwapJoinExit() internal virtual {
              // All joins, exits and swaps are disabled (except recovery mode exits).
              _ensureNotPaused();
          }
          // Internal functions
          /**
           * @dev Pays protocol fees by minting `bptAmount` to the Protocol Fee Collector.
           */
          function _payProtocolFees(uint256 bptAmount) internal {
              _mintPoolTokens(address(getProtocolFeesCollector()), bptAmount);
          }
          /**
           * @dev Adds swap fee amount to `amount`, returning a higher value.
           */
          function _addSwapFeeAmount(uint256 amount) internal view returns (uint256) {
              // This returns amount + fee amount, so we round up (favoring a higher fee amount).
              return amount.divUp(getSwapFeePercentage().complement());
          }
          /**
           * @dev Subtracts swap fee amount from `amount`, returning a lower value.
           */
          function _subtractSwapFeeAmount(uint256 amount) internal view returns (uint256) {
              // This returns amount - fee amount, so we round up (favoring a higher fee amount).
              uint256 feeAmount = amount.mulUp(getSwapFeePercentage());
              return amount.sub(feeAmount);
          }
          // Scaling
          /**
           * @dev Returns a scaling factor that, when multiplied to a token amount for `token`, normalizes its balance as if
           * it had 18 decimals.
           */
          function _computeScalingFactor(IERC20 token) internal view returns (uint256) {
              if (address(token) == address(this)) {
                  return FixedPoint.ONE;
              }
              // Tokens that don't implement the `decimals` method are not supported.
              uint256 tokenDecimals = ERC20(address(token)).decimals();
              // Tokens with more than 18 decimals are not supported.
              uint256 decimalsDifference = Math.sub(18, tokenDecimals);
              return FixedPoint.ONE * 10**decimalsDifference;
          }
          /**
           * @dev Returns the scaling factor for one of the Pool's tokens. Reverts if `token` is not a token registered by the
           * Pool.
           *
           * All scaling factors are fixed-point values with 18 decimals, to allow for this function to be overridden by
           * derived contracts that need to apply further scaling, making these factors potentially non-integer.
           *
           * The largest 'base' scaling factor (i.e. in tokens with less than 18 decimals) is 10**18, which in fixed-point is
           * 10**36. This value can be multiplied with a 112 bit Vault balance with no overflow by a factor of ~1e7, making
           * even relatively 'large' factors safe to use.
           *
           * The 1e7 figure is the result of 2**256 / (1e18 * 1e18 * 2**112).
           */
          function _scalingFactor(IERC20 token) internal view virtual returns (uint256);
          /**
           * @dev Same as `_scalingFactor()`, except for all registered tokens (in the same order as registered). The Vault
           * will always pass balances in this order when calling any of the Pool hooks.
           */
          function _scalingFactors() internal view virtual returns (uint256[] memory);
          function getScalingFactors() external view override returns (uint256[] memory) {
              return _scalingFactors();
          }
          /**
           * @dev Applies `scalingFactor` to `amount`, resulting in a larger or equal value depending on whether it needed
           * scaling or not.
           */
          function _upscale(uint256 amount, uint256 scalingFactor) internal pure returns (uint256) {
              // Upscale rounding wouldn't necessarily always go in the same direction: in a swap for example the balance of
              // token in should be rounded up, and that of token out rounded down. This is the only place where we round in
              // the same direction for all amounts, as the impact of this rounding is expected to be minimal (and there's no
              // rounding error unless `_scalingFactor()` is overriden).
              return FixedPoint.mulDown(amount, scalingFactor);
          }
          /**
           * @dev Same as `_upscale`, but for an entire array. This function does not return anything, but instead *mutates*
           * the `amounts` array.
           */
          function _upscaleArray(uint256[] memory amounts, uint256[] memory scalingFactors) internal pure {
              uint256 length = amounts.length;
              InputHelpers.ensureInputLengthMatch(length, scalingFactors.length);
              for (uint256 i = 0; i < length; ++i) {
                  amounts[i] = FixedPoint.mulDown(amounts[i], scalingFactors[i]);
              }
          }
          /**
           * @dev Reverses the `scalingFactor` applied to `amount`, resulting in a smaller or equal value depending on
           * whether it needed scaling or not. The result is rounded down.
           */
          function _downscaleDown(uint256 amount, uint256 scalingFactor) internal pure returns (uint256) {
              return FixedPoint.divDown(amount, scalingFactor);
          }
          /**
           * @dev Same as `_downscaleDown`, but for an entire array. This function does not return anything, but instead
           * *mutates* the `amounts` array.
           */
          function _downscaleDownArray(uint256[] memory amounts, uint256[] memory scalingFactors) internal pure {
              uint256 length = amounts.length;
              InputHelpers.ensureInputLengthMatch(length, scalingFactors.length);
              for (uint256 i = 0; i < length; ++i) {
                  amounts[i] = FixedPoint.divDown(amounts[i], scalingFactors[i]);
              }
          }
          /**
           * @dev Reverses the `scalingFactor` applied to `amount`, resulting in a smaller or equal value depending on
           * whether it needed scaling or not. The result is rounded up.
           */
          function _downscaleUp(uint256 amount, uint256 scalingFactor) internal pure returns (uint256) {
              return FixedPoint.divUp(amount, scalingFactor);
          }
          /**
           * @dev Same as `_downscaleUp`, but for an entire array. This function does not return anything, but instead
           * *mutates* the `amounts` array.
           */
          function _downscaleUpArray(uint256[] memory amounts, uint256[] memory scalingFactors) internal pure {
              uint256 length = amounts.length;
              InputHelpers.ensureInputLengthMatch(length, scalingFactors.length);
              for (uint256 i = 0; i < length; ++i) {
                  amounts[i] = FixedPoint.divUp(amounts[i], scalingFactors[i]);
              }
          }
          function _getAuthorizer() internal view override returns (IAuthorizer) {
              // Access control management is delegated to the Vault's Authorizer. This lets Balancer Governance manage which
              // accounts can call permissioned functions: for example, to perform emergency pauses.
              // If the owner is delegated, then *all* permissioned functions, including `setSwapFeePercentage`, will be under
              // Governance control.
              return getVault().getAuthorizer();
          }
          function _queryAction(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory balances,
              uint256 lastChangeBlock,
              uint256 protocolSwapFeePercentage,
              bytes memory userData,
              function(bytes32, address, address, uint256[] memory, uint256, uint256, uint256[] memory, bytes memory)
                  internal
                  returns (uint256, uint256[] memory) _action,
              function(uint256[] memory, uint256[] memory) internal view _downscaleArray
          ) private {
              // This uses the same technique used by the Vault in queryBatchSwap. Refer to that function for a detailed
              // explanation.
              if (msg.sender != address(this)) {
                  // We perform an external call to ourselves, forwarding the same calldata. In this call, the else clause of
                  // the preceding if statement will be executed instead.
                  // solhint-disable-next-line avoid-low-level-calls
                  (bool success, ) = address(this).call(msg.data);
                  // solhint-disable-next-line no-inline-assembly
                  assembly {
                      // This call should always revert to decode the bpt and token amounts from the revert reason
                      switch success
                          case 0 {
                              // Note we are manually writing the memory slot 0. We can safely overwrite whatever is
                              // stored there as we take full control of the execution and then immediately return.
                              // We copy the first 4 bytes to check if it matches with the expected signature, otherwise
                              // there was another revert reason and we should forward it.
                              returndatacopy(0, 0, 0x04)
                              let error := and(mload(0), 0xffffffff00000000000000000000000000000000000000000000000000000000)
                              // If the first 4 bytes don't match with the expected signature, we forward the revert reason.
                              if eq(eq(error, 0x43adbafb00000000000000000000000000000000000000000000000000000000), 0) {
                                  returndatacopy(0, 0, returndatasize())
                                  revert(0, returndatasize())
                              }
                              // The returndata contains the signature, followed by the raw memory representation of the
                              // `bptAmount` and `tokenAmounts` (array: length + data). We need to return an ABI-encoded
                              // representation of these.
                              // An ABI-encoded response will include one additional field to indicate the starting offset of
                              // the `tokenAmounts` array. The `bptAmount` will be laid out in the first word of the
                              // returndata.
                              //
                              // In returndata:
                              // [ signature ][ bptAmount ][ tokenAmounts length ][ tokenAmounts values ]
                              // [  4 bytes  ][  32 bytes ][       32 bytes      ][ (32 * length) bytes ]
                              //
                              // We now need to return (ABI-encoded values):
                              // [ bptAmount ][ tokeAmounts offset ][ tokenAmounts length ][ tokenAmounts values ]
                              // [  32 bytes ][       32 bytes     ][       32 bytes      ][ (32 * length) bytes ]
                              // We copy 32 bytes for the `bptAmount` from returndata into memory.
                              // Note that we skip the first 4 bytes for the error signature
                              returndatacopy(0, 0x04, 32)
                              // The offsets are 32-bytes long, so the array of `tokenAmounts` will start after
                              // the initial 64 bytes.
                              mstore(0x20, 64)
                              // We now copy the raw memory array for the `tokenAmounts` from returndata into memory.
                              // Since bpt amount and offset take up 64 bytes, we start copying at address 0x40. We also
                              // skip the first 36 bytes from returndata, which correspond to the signature plus bpt amount.
                              returndatacopy(0x40, 0x24, sub(returndatasize(), 36))
                              // We finally return the ABI-encoded uint256 and the array, which has a total length equal to
                              // the size of returndata, plus the 32 bytes of the offset but without the 4 bytes of the
                              // error signature.
                              return(0, add(returndatasize(), 28))
                          }
                          default {
                              // This call should always revert, but we fail nonetheless if that didn't happen
                              invalid()
                          }
                  }
              } else {
                  // This imitates the relevant parts of the bodies of onJoin and onExit. Since they're not virtual, we know
                  // that their implementations will match this regardless of what derived contracts might do.
                  _beforeSwapJoinExit();
                  uint256[] memory scalingFactors = _scalingFactors();
                  _upscaleArray(balances, scalingFactors);
                  (uint256 bptAmount, uint256[] memory tokenAmounts) = _action(
                      poolId,
                      sender,
                      recipient,
                      balances,
                      lastChangeBlock,
                      protocolSwapFeePercentage,
                      scalingFactors,
                      userData
                  );
                  _downscaleArray(tokenAmounts, scalingFactors);
                  // solhint-disable-next-line no-inline-assembly
                  assembly {
                      // We will return a raw representation of `bptAmount` and `tokenAmounts` in memory, which is composed of
                      // a 32-byte uint256, followed by a 32-byte for the array length, and finally the 32-byte uint256 values
                      // Because revert expects a size in bytes, we multiply the array length (stored at `tokenAmounts`) by 32
                      let size := mul(mload(tokenAmounts), 32)
                      // We store the `bptAmount` in the previous slot to the `tokenAmounts` array. We can make sure there
                      // will be at least one available slot due to how the memory scratch space works.
                      // We can safely overwrite whatever is stored in this slot as we will revert immediately after that.
                      let start := sub(tokenAmounts, 0x20)
                      mstore(start, bptAmount)
                      // We send one extra value for the error signature "QueryError(uint256,uint256[])" which is 0x43adbafb
                      // We use the previous slot to `bptAmount`.
                      mstore(sub(start, 0x20), 0x0000000000000000000000000000000000000000000000000000000043adbafb)
                      start := sub(start, 0x04)
                      // When copying from `tokenAmounts` into returndata, we copy the additional 68 bytes to also return
                      // the `bptAmount`, the array 's length, and the error signature.
                      revert(start, add(size, 68))
                  }
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "./IVault.sol";
      import "./IPoolSwapStructs.sol";
      /**
       * @dev Interface for adding and removing liquidity that all Pool contracts should implement. Note that this is not
       * the complete Pool contract interface, as it is missing the swap hooks. Pool contracts should also inherit from
       * either IGeneralPool or IMinimalSwapInfoPool
       */
      interface IBasePool is IPoolSwapStructs {
          /**
           * @dev Called by the Vault when a user calls `IVault.joinPool` to add liquidity to this Pool. Returns how many of
           * each registered token the user should provide, as well as the amount of protocol fees the Pool owes to the Vault.
           * The Vault will then take tokens from `sender` and add them to the Pool's balances, as well as collect
           * the reported amount in protocol fees, which the pool should calculate based on `protocolSwapFeePercentage`.
           *
           * Protocol fees are reported and charged on join events so that the Pool is free of debt whenever new users join.
           *
           * `sender` is the account performing the join (from which tokens will be withdrawn), and `recipient` is the account
           * designated to receive any benefits (typically pool shares). `balances` contains the total balances
           * for each token the Pool registered in the Vault, in the same order that `IVault.getPoolTokens` would return.
           *
           * `lastChangeBlock` is the last block in which *any* of the Pool's registered tokens last changed its total
           * balance.
           *
           * `userData` contains any pool-specific instructions needed to perform the calculations, such as the type of
           * join (e.g., proportional given an amount of pool shares, single-asset, multi-asset, etc.)
           *
           * Contracts implementing this function should check that the caller is indeed the Vault before performing any
           * state-changing operations, such as minting pool shares.
           */
          function onJoinPool(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory balances,
              uint256 lastChangeBlock,
              uint256 protocolSwapFeePercentage,
              bytes memory userData
          ) external returns (uint256[] memory amountsIn, uint256[] memory dueProtocolFeeAmounts);
          /**
           * @dev Called by the Vault when a user calls `IVault.exitPool` to remove liquidity from this Pool. Returns how many
           * tokens the Vault should deduct from the Pool's balances, as well as the amount of protocol fees the Pool owes
           * to the Vault. The Vault will then take tokens from the Pool's balances and send them to `recipient`,
           * as well as collect the reported amount in protocol fees, which the Pool should calculate based on
           * `protocolSwapFeePercentage`.
           *
           * Protocol fees are charged on exit events to guarantee that users exiting the Pool have paid their share.
           *
           * `sender` is the account performing the exit (typically the pool shareholder), and `recipient` is the account
           * to which the Vault will send the proceeds. `balances` contains the total token balances for each token
           * the Pool registered in the Vault, in the same order that `IVault.getPoolTokens` would return.
           *
           * `lastChangeBlock` is the last block in which *any* of the Pool's registered tokens last changed its total
           * balance.
           *
           * `userData` contains any pool-specific instructions needed to perform the calculations, such as the type of
           * exit (e.g., proportional given an amount of pool shares, single-asset, multi-asset, etc.)
           *
           * Contracts implementing this function should check that the caller is indeed the Vault before performing any
           * state-changing operations, such as burning pool shares.
           */
          function onExitPool(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory balances,
              uint256 lastChangeBlock,
              uint256 protocolSwapFeePercentage,
              bytes memory userData
          ) external returns (uint256[] memory amountsOut, uint256[] memory dueProtocolFeeAmounts);
          /**
           * @dev Returns this Pool's ID, used when interacting with the Vault (to e.g. join the Pool or swap with it).
           */
          function getPoolId() external view returns (bytes32);
          /**
           * @dev Returns the current swap fee percentage as a 18 decimal fixed point number, so e.g. 1e17 corresponds to a
           * 10% swap fee.
           */
          function getSwapFeePercentage() external view returns (uint256);
          /**
           * @dev Returns the scaling factors of each of the Pool's tokens. This is an implementation detail that is typically
           * not relevant for outside parties, but which might be useful for some types of Pools.
           */
          function getScalingFactors() external view returns (uint256[] memory);
          function queryJoin(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory balances,
              uint256 lastChangeBlock,
              uint256 protocolSwapFeePercentage,
              bytes memory userData
          ) external returns (uint256 bptOut, uint256[] memory amountsIn);
          function queryExit(
              bytes32 poolId,
              address sender,
              address recipient,
              uint256[] memory balances,
              uint256 lastChangeBlock,
              uint256 protocolSwapFeePercentage,
              bytes memory userData
          ) external returns (uint256 bptIn, uint256[] memory amountsOut);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../solidity-utils/openzeppelin/IERC20.sol";
      import "./IVault.sol";
      interface IPoolSwapStructs {
          // This is not really an interface - it just defines common structs used by other interfaces: IGeneralPool and
          // IMinimalSwapInfoPool.
          //
          // This data structure represents a request for a token swap, where `kind` indicates the swap type ('given in' or
          // 'given out') which indicates whether or not the amount sent by the pool is known.
          //
          // The pool receives `tokenIn` and sends `tokenOut`. `amount` is the number of `tokenIn` tokens the pool will take
          // in, or the number of `tokenOut` tokens the Pool will send out, depending on the given swap `kind`.
          //
          // All other fields are not strictly necessary for most swaps, but are provided to support advanced scenarios in
          // some Pools.
          //
          // `poolId` is the ID of the Pool involved in the swap - this is useful for Pool contracts that implement more than
          // one Pool.
          //
          // The meaning of `lastChangeBlock` depends on the Pool specialization:
          //  - Two Token or Minimal Swap Info: the last block in which either `tokenIn` or `tokenOut` changed its total
          //    balance.
          //  - General: the last block in which *any* of the Pool's registered tokens changed its total balance.
          //
          // `from` is the origin address for the funds the Pool receives, and `to` is the destination address
          // where the Pool sends the outgoing tokens.
          //
          // `userData` is extra data provided by the caller - typically a signature from a trusted party.
          struct SwapRequest {
              IVault.SwapKind kind;
              IERC20 tokenIn;
              IERC20 tokenOut;
              uint256 amount;
              // Misc data
              bytes32 poolId;
              uint256 lastChangeBlock;
              address from;
              address to;
              bytes userData;
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      pragma experimental ABIEncoderV2;
      import "../solidity-utils/openzeppelin/IERC20.sol";
      interface IAssetManager {
          /**
           * @notice Emitted when asset manager is rebalanced
           */
          event Rebalance(bytes32 poolId);
          /**
           * @notice Sets the config
           */
          function setConfig(bytes32 poolId, bytes calldata config) external;
          /**
           * Note: No function to read the asset manager config is included in IAssetManager
           * as the signature is expected to vary between asset manager implementations
           */
          /**
           * @notice Returns the asset manager's token
           */
          function getToken() external view returns (IERC20);
          /**
           * @return the current assets under management of this asset manager
           */
          function getAUM(bytes32 poolId) external view returns (uint256);
          /**
           * @return poolCash - The up-to-date cash balance of the pool
           * @return poolManaged - The up-to-date managed balance of the pool
           */
          function getPoolBalances(bytes32 poolId) external view returns (uint256 poolCash, uint256 poolManaged);
          /**
           * @return The difference in tokens between the target investment
           * and the currently invested amount (i.e. the amount that can be invested)
           */
          function maxInvestableBalance(bytes32 poolId) external view returns (int256);
          /**
           * @notice Updates the Vault on the value of the pool's investment returns
           */
          function updateBalanceOfPool(bytes32 poolId) external;
          /**
           * @notice Determines whether the pool should rebalance given the provided balances
           */
          function shouldRebalance(uint256 cash, uint256 managed) external view returns (bool);
          /**
           * @notice Rebalances funds between the pool and the asset manager to maintain target investment percentage.
           * @param poolId - the poolId of the pool to be rebalanced
           * @param force - a boolean representing whether a rebalance should be forced even when the pool is near balance
           */
          function rebalance(bytes32 poolId, bool force) external;
          /**
           * @notice allows an authorized rebalancer to remove capital to facilitate large withdrawals
           * @param poolId - the poolId of the pool to withdraw funds back to
           * @param amount - the amount of tokens to withdraw back to the pool
           */
          function capitalOut(bytes32 poolId, uint256 amount) external;
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "../solidity-utils/openzeppelin/IERC20.sol";
      interface IControlledPool {
          function setSwapFeePercentage(uint256 swapFeePercentage) external;
          function setAssetManagerPoolConfig(IERC20 token, bytes memory poolConfig) external;
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      import "../math/Math.sol";
      /**
       * @dev Library for encoding and decoding values stored inside a 256 bit word. Typically used to pack multiple values in
       * a single storage slot, saving gas by performing less storage accesses.
       *
       * Each value is defined by its size and the least significant bit in the word, also known as offset. For example, two
       * 128 bit values may be encoded in a word by assigning one an offset of 0, and the other an offset of 128.
       *
       * We could use Solidity structs to pack values together in a single storage slot instead of relying on a custom and
       * error-prone library, but unfortunately Solidity only allows for structs to live in either storage, calldata or
       * memory. Because a memory struct uses not just memory but also a slot in the stack (to store its memory location),
       * using memory for word-sized values (i.e. of 256 bits or less) is strictly less gas performant, and doesn't even
       * prevent stack-too-deep issues. This is compounded by the fact that Balancer contracts typically are memory-intensive,
       * and the cost of accesing memory increases quadratically with the number of allocated words. Manual packing and
       * unpacking is therefore the preferred approach.
       */
      library WordCodec {
          // Masks are values with the least significant N bits set. They can be used to extract an encoded value from a word,
          // or to insert a new one replacing the old.
          uint256 private constant _MASK_1 = 2**(1) - 1;
          uint256 private constant _MASK_192 = 2**(192) - 1;
          // In-place insertion
          /**
           * @dev Inserts an unsigned integer of bitLength, shifted by an offset, into a 256 bit word,
           * replacing the old value. Returns the new word.
           */
          function insertUint(
              bytes32 word,
              uint256 value,
              uint256 offset,
              uint256 bitLength
          ) internal pure returns (bytes32) {
              _validateEncodingParams(value, offset, bitLength);
              uint256 mask = (1 << bitLength) - 1;
              bytes32 clearedWord = bytes32(uint256(word) & ~(mask << offset));
              return clearedWord | bytes32(value << offset);
          }
          /**
           * @dev Inserts a signed integer shifted by an offset into a 256 bit word, replacing the old value. Returns
           * the new word.
           *
           * Assumes `value` can be represented using `bitLength` bits.
           */
          function insertInt(
              bytes32 word,
              int256 value,
              uint256 offset,
              uint256 bitLength
          ) internal pure returns (bytes32) {
              _validateEncodingParams(value, offset, bitLength);
              uint256 mask = (1 << bitLength) - 1;
              bytes32 clearedWord = bytes32(uint256(word) & ~(mask << offset));
              // Integer values need masking to remove the upper bits of negative values.
              return clearedWord | bytes32((uint256(value) & mask) << offset);
          }
          // Encoding
          /**
           * @dev Encodes an unsigned integer shifted by an offset. Ensures value fits within
           * `bitLength` bits.
           *
           * The return value can be ORed bitwise with other encoded values to form a 256 bit word.
           */
          function encodeUint(
              uint256 value,
              uint256 offset,
              uint256 bitLength
          ) internal pure returns (bytes32) {
              _validateEncodingParams(value, offset, bitLength);
              return bytes32(value << offset);
          }
          /**
           * @dev Encodes a signed integer shifted by an offset.
           *
           * The return value can be ORed bitwise with other encoded values to form a 256 bit word.
           */
          function encodeInt(
              int256 value,
              uint256 offset,
              uint256 bitLength
          ) internal pure returns (bytes32) {
              _validateEncodingParams(value, offset, bitLength);
              uint256 mask = (1 << bitLength) - 1;
              // Integer values need masking to remove the upper bits of negative values.
              return bytes32((uint256(value) & mask) << offset);
          }
          // Decoding
          /**
           * @dev Decodes and returns an unsigned integer with `bitLength` bits, shifted by an offset, from a 256 bit word.
           */
          function decodeUint(
              bytes32 word,
              uint256 offset,
              uint256 bitLength
          ) internal pure returns (uint256) {
              return uint256(word >> offset) & ((1 << bitLength) - 1);
          }
          /**
           * @dev Decodes and returns a signed integer with `bitLength` bits, shifted by an offset, from a 256 bit word.
           */
          function decodeInt(
              bytes32 word,
              uint256 offset,
              uint256 bitLength
          ) internal pure returns (int256) {
              int256 maxInt = int256((1 << (bitLength - 1)) - 1);
              uint256 mask = (1 << bitLength) - 1;
              int256 value = int256(uint256(word >> offset) & mask);
              // In case the decoded value is greater than the max positive integer that can be represented with bitLength
              // bits, we know it was originally a negative integer. Therefore, we mask it to restore the sign in the 256 bit
              // representation.
              return value > maxInt ? (value | int256(~mask)) : value;
          }
          // Special cases
          /**
           * @dev Decodes and returns a boolean shifted by an offset from a 256 bit word.
           */
          function decodeBool(bytes32 word, uint256 offset) internal pure returns (bool) {
              return (uint256(word >> offset) & _MASK_1) == 1;
          }
          /**
           * @dev Inserts a 192 bit value shifted by an offset into a 256 bit word, replacing the old value.
           * Returns the new word.
           *
           * Assumes `value` can be represented using 192 bits.
           */
          function insertBits192(
              bytes32 word,
              bytes32 value,
              uint256 offset
          ) internal pure returns (bytes32) {
              bytes32 clearedWord = bytes32(uint256(word) & ~(_MASK_192 << offset));
              return clearedWord | bytes32((uint256(value) & _MASK_192) << offset);
          }
          /**
           * @dev Inserts a boolean value shifted by an offset into a 256 bit word, replacing the old value. Returns the new
           * word.
           */
          function insertBool(
              bytes32 word,
              bool value,
              uint256 offset
          ) internal pure returns (bytes32) {
              bytes32 clearedWord = bytes32(uint256(word) & ~(_MASK_1 << offset));
              return clearedWord | bytes32(uint256(value ? 1 : 0) << offset);
          }
          // Helpers
          function _validateEncodingParams(
              uint256 value,
              uint256 offset,
              uint256 bitLength
          ) private pure {
              _require(offset < 256, Errors.OUT_OF_BOUNDS);
              // We never accept 256 bit values (which would make the codec pointless), and the larger the offset the smaller
              // the maximum bit length.
              _require(bitLength >= 1 && bitLength <= Math.min(255, 256 - offset), Errors.OUT_OF_BOUNDS);
              // Testing unsigned values for size is straightforward: their upper bits must be cleared.
              _require(value >> bitLength == 0, Errors.CODEC_OVERFLOW);
          }
          function _validateEncodingParams(
              int256 value,
              uint256 offset,
              uint256 bitLength
          ) private pure {
              _require(offset < 256, Errors.OUT_OF_BOUNDS);
              // We never accept 256 bit values (which would make the codec pointless), and the larger the offset the smaller
              // the maximum bit length.
              _require(bitLength >= 1 && bitLength <= Math.min(255, 256 - offset), Errors.OUT_OF_BOUNDS);
              // Testing signed values for size is a bit more involved.
              if (value >= 0) {
                  // For positive values, we can simply check that the upper bits are clear. Notice we remove one bit from the
                  // length for the sign bit.
                  _require(value >> (bitLength - 1) == 0, Errors.CODEC_OVERFLOW);
              } else {
                  // Negative values can receive the same treatment by making them positive, with the caveat that the range
                  // for negative values in two's complement supports one more value than for the positive case.
                  _require(Math.abs(value + 1) >> (bitLength - 1) == 0, Errors.CODEC_OVERFLOW);
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/ITemporarilyPausable.sol";
      /**
       * @dev Allows for a contract to be paused during an initial period after deployment, disabling functionality. Can be
       * used as an emergency switch in case a security vulnerability or threat is identified.
       *
       * The contract can only be paused during the Pause Window, a period that starts at deployment. It can also be
       * unpaused and repaused any number of times during this period. This is intended to serve as a safety measure: it lets
       * system managers react quickly to potentially dangerous situations, knowing that this action is reversible if careful
       * analysis later determines there was a false alarm.
       *
       * If the contract is paused when the Pause Window finishes, it will remain in the paused state through an additional
       * Buffer Period, after which it will be automatically unpaused forever. This is to ensure there is always enough time
       * to react to an emergency, even if the threat is discovered shortly before the Pause Window expires.
       *
       * Note that since the contract can only be paused within the Pause Window, unpausing during the Buffer Period is
       * irreversible.
       */
      abstract contract TemporarilyPausable is ITemporarilyPausable {
          // The Pause Window and Buffer Period are timestamp-based: they should not be relied upon for sub-minute accuracy.
          // solhint-disable not-rely-on-time
          uint256 private constant _MAX_PAUSE_WINDOW_DURATION = 90 days;
          uint256 private constant _MAX_BUFFER_PERIOD_DURATION = 30 days;
          uint256 private immutable _pauseWindowEndTime;
          uint256 private immutable _bufferPeriodEndTime;
          bool private _paused;
          constructor(uint256 pauseWindowDuration, uint256 bufferPeriodDuration) {
              _require(pauseWindowDuration <= _MAX_PAUSE_WINDOW_DURATION, Errors.MAX_PAUSE_WINDOW_DURATION);
              _require(bufferPeriodDuration <= _MAX_BUFFER_PERIOD_DURATION, Errors.MAX_BUFFER_PERIOD_DURATION);
              uint256 pauseWindowEndTime = block.timestamp + pauseWindowDuration;
              _pauseWindowEndTime = pauseWindowEndTime;
              _bufferPeriodEndTime = pauseWindowEndTime + bufferPeriodDuration;
          }
          /**
           * @dev Reverts if the contract is paused.
           */
          modifier whenNotPaused() {
              _ensureNotPaused();
              _;
          }
          /**
           * @dev Returns the current contract pause status, as well as the end times of the Pause Window and Buffer
           * Period.
           */
          function getPausedState()
              external
              view
              override
              returns (
                  bool paused,
                  uint256 pauseWindowEndTime,
                  uint256 bufferPeriodEndTime
              )
          {
              paused = !_isNotPaused();
              pauseWindowEndTime = _getPauseWindowEndTime();
              bufferPeriodEndTime = _getBufferPeriodEndTime();
          }
          /**
           * @dev Sets the pause state to `paused`. The contract can only be paused until the end of the Pause Window, and
           * unpaused until the end of the Buffer Period.
           *
           * Once the Buffer Period expires, this function reverts unconditionally.
           */
          function _setPaused(bool paused) internal {
              if (paused) {
                  _require(block.timestamp < _getPauseWindowEndTime(), Errors.PAUSE_WINDOW_EXPIRED);
              } else {
                  _require(block.timestamp < _getBufferPeriodEndTime(), Errors.BUFFER_PERIOD_EXPIRED);
              }
              _paused = paused;
              emit PausedStateChanged(paused);
          }
          /**
           * @dev Reverts if the contract is paused.
           */
          function _ensureNotPaused() internal view {
              _require(_isNotPaused(), Errors.PAUSED);
          }
          /**
           * @dev Reverts if the contract is not paused.
           */
          function _ensurePaused() internal view {
              _require(!_isNotPaused(), Errors.NOT_PAUSED);
          }
          /**
           * @dev Returns true if the contract is unpaused.
           *
           * Once the Buffer Period expires, the gas cost of calling this function is reduced dramatically, as storage is no
           * longer accessed.
           */
          function _isNotPaused() internal view returns (bool) {
              // After the Buffer Period, the (inexpensive) timestamp check short-circuits the storage access.
              return block.timestamp > _getBufferPeriodEndTime() || !_paused;
          }
          // These getters lead to reduced bytecode size by inlining the immutable variables in a single place.
          function _getPauseWindowEndTime() private view returns (uint256) {
              return _pauseWindowEndTime;
          }
          function _getBufferPeriodEndTime() private view returns (uint256) {
              return _bufferPeriodEndTime;
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/openzeppelin/IERC20.sol";
      import "./SafeMath.sol";
      /**
       * @dev Implementation of the {IERC20} interface.
       *
       * This implementation is agnostic to the way tokens are created. This means
       * that a supply mechanism has to be added in a derived contract using {_mint}.
       * For a generic mechanism see {ERC20PresetMinterPauser}.
       *
       * TIP: For a detailed writeup see our guide
       * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
       * to implement supply mechanisms].
       *
       * We have followed general OpenZeppelin guidelines: functions revert instead
       * of returning `false` on failure. This behavior is nonetheless conventional
       * and does not conflict with the expectations of ERC20 applications.
       *
       * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
       * This allows applications to reconstruct the allowance for all accounts just
       * by listening to said events. Other implementations of the EIP may not emit
       * these events, as it isn't required by the specification.
       *
       * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
       * functions have been added to mitigate the well-known issues around setting
       * allowances. See {IERC20-approve}.
       */
      contract ERC20 is IERC20 {
          using SafeMath for uint256;
          mapping(address => uint256) private _balances;
          mapping(address => mapping(address => uint256)) private _allowances;
          uint256 private _totalSupply;
          string private _name;
          string private _symbol;
          uint8 private _decimals;
          /**
           * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
           * a default value of 18.
           *
           * To select a different value for {decimals}, use {_setupDecimals}.
           *
           * All three of these values are immutable: they can only be set once during
           * construction.
           */
          constructor(string memory name_, string memory symbol_) {
              _name = name_;
              _symbol = symbol_;
              _decimals = 18;
          }
          /**
           * @dev Returns the name of the token.
           */
          function name() public view returns (string memory) {
              return _name;
          }
          /**
           * @dev Returns the symbol of the token, usually a shorter version of the
           * name.
           */
          function symbol() public view returns (string memory) {
              return _symbol;
          }
          /**
           * @dev Returns the number of decimals used to get its user representation.
           * For example, if `decimals` equals `2`, a balance of `505` tokens should
           * be displayed to a user as `5,05` (`505 / 10 ** 2`).
           *
           * Tokens usually opt for a value of 18, imitating the relationship between
           * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
           * called.
           *
           * NOTE: This information is only used for _display_ purposes: it in
           * no way affects any of the arithmetic of the contract, including
           * {IERC20-balanceOf} and {IERC20-transfer}.
           */
          function decimals() public view returns (uint8) {
              return _decimals;
          }
          /**
           * @dev See {IERC20-totalSupply}. The total supply should only be read using this function
           *
           * Can be overridden by derived contracts to store the total supply in a different way (e.g. packed with other
           * storage values).
           */
          function totalSupply() public view virtual override returns (uint256) {
              return _totalSupply;
          }
          /**
           * @dev Sets a new value for the total supply. It should only be set using this function.
           *
           * * Can be overridden by derived contracts to store the total supply in a different way (e.g. packed with other
           * storage values).
           */
          function _setTotalSupply(uint256 value) internal virtual {
              _totalSupply = value;
          }
          /**
           * @dev See {IERC20-balanceOf}.
           */
          function balanceOf(address account) public view override returns (uint256) {
              return _balances[account];
          }
          /**
           * @dev See {IERC20-transfer}.
           *
           * Requirements:
           *
           * - `recipient` cannot be the zero address.
           * - the caller must have a balance of at least `amount`.
           */
          function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
              _transfer(msg.sender, recipient, amount);
              return true;
          }
          /**
           * @dev See {IERC20-allowance}.
           */
          function allowance(address owner, address spender) public view virtual override returns (uint256) {
              return _allowances[owner][spender];
          }
          /**
           * @dev See {IERC20-approve}.
           *
           * Requirements:
           *
           * - `spender` cannot be the zero address.
           */
          function approve(address spender, uint256 amount) public virtual override returns (bool) {
              _approve(msg.sender, spender, amount);
              return true;
          }
          /**
           * @dev See {IERC20-transferFrom}.
           *
           * Emits an {Approval} event indicating the updated allowance. This is not
           * required by the EIP. See the note at the beginning of {ERC20}.
           *
           * Requirements:
           *
           * - `sender` and `recipient` cannot be the zero address.
           * - `sender` must have a balance of at least `amount`.
           * - the caller must have allowance for ``sender``'s tokens of at least
           * `amount`.
           */
          function transferFrom(
              address sender,
              address recipient,
              uint256 amount
          ) public virtual override returns (bool) {
              _transfer(sender, recipient, amount);
              _approve(
                  sender,
                  msg.sender,
                  _allowances[sender][msg.sender].sub(amount, Errors.ERC20_TRANSFER_EXCEEDS_ALLOWANCE)
              );
              return true;
          }
          /**
           * @dev Atomically increases the allowance granted to `spender` by the caller.
           *
           * This is an alternative to {approve} that can be used as a mitigation for
           * problems described in {IERC20-approve}.
           *
           * Emits an {Approval} event indicating the updated allowance.
           *
           * Requirements:
           *
           * - `spender` cannot be the zero address.
           */
          function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
              _approve(msg.sender, spender, _allowances[msg.sender][spender].add(addedValue));
              return true;
          }
          /**
           * @dev Atomically decreases the allowance granted to `spender` by the caller.
           *
           * This is an alternative to {approve} that can be used as a mitigation for
           * problems described in {IERC20-approve}.
           *
           * Emits an {Approval} event indicating the updated allowance.
           *
           * Requirements:
           *
           * - `spender` cannot be the zero address.
           * - `spender` must have allowance for the caller of at least
           * `subtractedValue`.
           */
          function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
              _approve(
                  msg.sender,
                  spender,
                  _allowances[msg.sender][spender].sub(subtractedValue, Errors.ERC20_DECREASED_ALLOWANCE_BELOW_ZERO)
              );
              return true;
          }
          /**
           * @dev Moves tokens `amount` from `sender` to `recipient`.
           *
           * This is internal function is equivalent to {transfer}, and can be used to
           * e.g. implement automatic token fees, slashing mechanisms, etc.
           *
           * Emits a {Transfer} event.
           *
           * Requirements:
           *
           * - `sender` cannot be the zero address.
           * - `recipient` cannot be the zero address.
           * - `sender` must have a balance of at least `amount`.
           */
          function _transfer(
              address sender,
              address recipient,
              uint256 amount
          ) internal virtual {
              _require(sender != address(0), Errors.ERC20_TRANSFER_FROM_ZERO_ADDRESS);
              _require(recipient != address(0), Errors.ERC20_TRANSFER_TO_ZERO_ADDRESS);
              _beforeTokenTransfer(sender, recipient, amount);
              _balances[sender] = _balances[sender].sub(amount, Errors.ERC20_TRANSFER_EXCEEDS_BALANCE);
              _balances[recipient] = _balances[recipient].add(amount);
              emit Transfer(sender, recipient, amount);
          }
          /** @dev Creates `amount` tokens and assigns them to `account`, increasing
           * the total supply.
           *
           * Emits a {Transfer} event with `from` set to the zero address.
           *
           * Requirements:
           *
           * - `to` cannot be the zero address.
           */
          function _mint(address account, uint256 amount) internal virtual {
              _beforeTokenTransfer(address(0), account, amount);
              _setTotalSupply(totalSupply().add(amount));
              _balances[account] = _balances[account].add(amount);
              emit Transfer(address(0), account, amount);
          }
          /**
           * @dev Destroys `amount` tokens from `account`, reducing the
           * total supply.
           *
           * Emits a {Transfer} event with `to` set to the zero address.
           *
           * Requirements:
           *
           * - `account` cannot be the zero address.
           * - `account` must have at least `amount` tokens.
           */
          function _burn(address account, uint256 amount) internal virtual {
              _require(account != address(0), Errors.ERC20_BURN_FROM_ZERO_ADDRESS);
              _beforeTokenTransfer(account, address(0), amount);
              _balances[account] = _balances[account].sub(amount, Errors.ERC20_BURN_EXCEEDS_BALANCE);
              _setTotalSupply(totalSupply().sub(amount));
              emit Transfer(account, address(0), amount);
          }
          /**
           * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
           *
           * This internal function is equivalent to `approve`, and can be used to
           * e.g. set automatic allowances for certain subsystems, etc.
           *
           * Emits an {Approval} event.
           *
           * Requirements:
           *
           * - `owner` cannot be the zero address.
           * - `spender` cannot be the zero address.
           */
          function _approve(
              address owner,
              address spender,
              uint256 amount
          ) internal virtual {
              _allowances[owner][spender] = amount;
              emit Approval(owner, spender, amount);
          }
          /**
           * @dev Sets {decimals} to a value other than the default one of 18.
           *
           * WARNING: This function should only be called from the constructor. Most
           * applications that interact with token contracts will not expect
           * {decimals} to ever change, and may work incorrectly if it does.
           */
          function _setupDecimals(uint8 decimals_) internal {
              _decimals = decimals_;
          }
          /**
           * @dev Hook that is called before any transfer of tokens. This includes
           * minting and burning.
           *
           * Calling conditions:
           *
           * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
           * will be to transferred to `to`.
           * - when `from` is zero, `amount` tokens will be minted for `to`.
           * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
           * - `from` and `to` are never both zero.
           *
           * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
           */
          function _beforeTokenTransfer(
              address from,
              address to,
              uint256 amount
          ) internal virtual {
              // solhint-disable-previous-line no-empty-blocks
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/vault/IVault.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/openzeppelin/ERC20Permit.sol";
      /**
       * @title Highly opinionated token implementation
       * @author Balancer Labs
       * @dev
       * - Includes functions to increase and decrease allowance as a workaround
       *   for the well-known issue with `approve`:
       *   https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
       * - Allows for 'infinite allowance', where an allowance of 0xff..ff is not
       *   decreased by calls to transferFrom
       * - Lets a token holder use `transferFrom` to send their own tokens,
       *   without first setting allowance
       * - Emits 'Approval' events whenever allowance is changed by `transferFrom`
       * - Assigns infinite allowance for all token holders to the Vault
       */
      contract BalancerPoolToken is ERC20Permit {
          IVault private immutable _vault;
          constructor(
              string memory tokenName,
              string memory tokenSymbol,
              IVault vault
          ) ERC20(tokenName, tokenSymbol) ERC20Permit(tokenName) {
              _vault = vault;
          }
          function getVault() public view returns (IVault) {
              return _vault;
          }
          // Overrides
          /**
           * @dev Override to grant the Vault infinite allowance, causing for Pool Tokens to not require approval.
           *
           * This is sound as the Vault already provides authorization mechanisms when initiation token transfers, which this
           * contract inherits.
           */
          function allowance(address owner, address spender) public view override returns (uint256) {
              if (spender == address(getVault())) {
                  return uint256(-1);
              } else {
                  return super.allowance(owner, spender);
              }
          }
          /**
           * @dev Override to allow for 'infinite allowance' and let the token owner use `transferFrom` with no self-allowance
           */
          function transferFrom(
              address sender,
              address recipient,
              uint256 amount
          ) public override returns (bool) {
              uint256 currentAllowance = allowance(sender, msg.sender);
              _require(msg.sender == sender || currentAllowance >= amount, Errors.ERC20_TRANSFER_EXCEEDS_ALLOWANCE);
              _transfer(sender, recipient, amount);
              if (msg.sender != sender && currentAllowance != uint256(-1)) {
                  // Because of the previous require, we know that if msg.sender != sender then currentAllowance >= amount
                  _approve(sender, msg.sender, currentAllowance - amount);
              }
              return true;
          }
          /**
           * @dev Override to allow decreasing allowance by more than the current amount (setting it to zero)
           */
          function decreaseAllowance(address spender, uint256 amount) public override returns (bool) {
              uint256 currentAllowance = allowance(msg.sender, spender);
              if (amount >= currentAllowance) {
                  _approve(msg.sender, spender, 0);
              } else {
                  // No risk of underflow due to if condition
                  _approve(msg.sender, spender, currentAllowance - amount);
              }
              return true;
          }
          // Internal functions
          function _mintPoolTokens(address recipient, uint256 amount) internal {
              _mint(recipient, amount);
          }
          function _burnPoolTokens(address sender, uint256 amount) internal {
              _burn(sender, amount);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/vault/IAuthorizer.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/helpers/Authentication.sol";
      /**
       * @dev Base authorization layer implementation for Pools.
       *
       * The owner account can call some of the permissioned functions - access control of the rest is delegated to the
       * Authorizer. Note that this owner is immutable: more sophisticated permission schemes, such as multiple ownership,
       * granular roles, etc., could be built on top of this by making the owner a smart contract.
       *
       * Access control of all other permissioned functions is delegated to an Authorizer. It is also possible to delegate
       * control of *all* permissioned functions to the Authorizer by setting the owner address to `_DELEGATE_OWNER`.
       */
      abstract contract BasePoolAuthorization is Authentication {
          address private immutable _owner;
          address private constant _DELEGATE_OWNER = 0xBA1BA1ba1BA1bA1bA1Ba1BA1ba1BA1bA1ba1ba1B;
          constructor(address owner) {
              _owner = owner;
          }
          function getOwner() public view returns (address) {
              return _owner;
          }
          function getAuthorizer() external view returns (IAuthorizer) {
              return _getAuthorizer();
          }
          function _canPerform(bytes32 actionId, address account) internal view override returns (bool) {
              if ((getOwner() != _DELEGATE_OWNER) && _isOwnerOnlyAction(actionId)) {
                  // Only the owner can perform "owner only" actions, unless the owner is delegated.
                  return msg.sender == getOwner();
              } else {
                  // Non-owner actions are always processed via the Authorizer, as "owner only" ones are when delegated.
                  return _getAuthorizer().canPerform(actionId, account, address(this));
              }
          }
          function _isOwnerOnlyAction(bytes32) internal view virtual returns (bool) {
              return false;
          }
          function _getAuthorizer() internal view virtual returns (IAuthorizer);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      import "@balancer-labs/v2-interfaces/contracts/pool-utils/BasePoolUserData.sol";
      import "@balancer-labs/v2-interfaces/contracts/pool-utils/IRecoveryMode.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/math/FixedPoint.sol";
      import "./BasePoolAuthorization.sol";
      /**
       * @notice Handle storage and state changes for pools that support "Recovery Mode".
       *
       * @dev This is intended to provide a safe way to exit any pool during some kind of emergency, to avoid locking funds
       * in the event the pool enters a non-functional state (i.e., some code that normally runs during exits is causing
       * them to revert).
       *
       * Recovery Mode is *not* the same as pausing the pool. The pause function is only available during a short window
       * after factory deployment. Pausing can only be intentionally reversed during a buffer period, and the contract
       * will permanently unpause itself thereafter. Paused pools are completely disabled, in a kind of suspended animation,
       * until they are voluntarily or involuntarily unpaused.
       *
       * By contrast, a privileged account - typically a governance multisig - can place a pool in Recovery Mode at any
       * time, and it is always reversible. The pool is *not* disabled while in this mode: though of course whatever
       * condition prompted the transition to Recovery Mode has likely effectively disabled some functions. Rather,
       * a special "clean" exit is enabled, which runs the absolute minimum code necessary to exit proportionally.
       * In particular, stable pools do not attempt to compute the invariant (which is a complex, iterative calculation
       * that can fail in extreme circumstances), and no protocol fees are collected.
       *
       * It is critical to ensure that turning on Recovery Mode would do no harm, if activated maliciously or in error.
       */
      abstract contract RecoveryMode is IRecoveryMode, BasePoolAuthorization {
          using FixedPoint for uint256;
          using BasePoolUserData for bytes;
          /**
           * @dev Reverts if the contract is in Recovery Mode.
           */
          modifier whenNotInRecoveryMode() {
              _ensureNotInRecoveryMode();
              _;
          }
          /**
           * @notice Enable recovery mode, which enables a special safe exit path for LPs.
           * @dev Does not otherwise affect pool operations (beyond deferring payment of protocol fees), though some pools may
           * perform certain operations in a "safer" manner that is less likely to fail, in an attempt to keep the pool
           * running, even in a pathological state. Unlike the Pause operation, which is only available during a short window
           * after factory deployment, Recovery Mode can always be enabled.
           */
          function enableRecoveryMode() external override authenticate {
              _setRecoveryMode(true);
          }
          /**
           * @notice Disable recovery mode, which disables the special safe exit path for LPs.
           * @dev Protocol fees are not paid while in Recovery Mode, so it should only remain active for as long as strictly
           * necessary.
           *
           * This function will revert when called within a Vault context (i.e. in the middle of a join or an exit).
           *
           * This function depends on the invariant value, which may be calculated incorrectly in the middle of a join or
           * an exit, because the state of the pool could be out of sync with the state of the Vault.
           * `_onDisableRecoveryMode` will revert when called from such a context for composable stable pools, effectively
           * protecting this function.
           *
           * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
           */
          function disableRecoveryMode() external override authenticate {
              _setRecoveryMode(false);
          }
          // Defer implementation for functions that require storage
          /**
           * @notice Override to check storage and return whether the pool is in Recovery Mode
           */
          function inRecoveryMode() public view virtual override returns (bool);
          /**
           * @dev Override to update storage and emit the event
           *
           * No complex code or external calls that could fail should be placed in the implementations,
           * which could jeopardize the ability to enable and disable Recovery Mode.
           */
          function _setRecoveryMode(bool enabled) internal virtual;
          /**
           * @dev Reverts if the contract is not in Recovery Mode.
           */
          function _ensureInRecoveryMode() internal view {
              _require(inRecoveryMode(), Errors.NOT_IN_RECOVERY_MODE);
          }
          /**
           * @dev Reverts if the contract is in Recovery Mode.
           */
          function _ensureNotInRecoveryMode() internal view {
              _require(!inRecoveryMode(), Errors.IN_RECOVERY_MODE);
          }
          /**
           * @dev A minimal proportional exit, suitable as is for most pools: though not for pools with preminted BPT
           * or other special considerations. Designed to be overridden if a pool needs to do extra processing,
           * such as scaling a stored invariant, or caching the new total supply.
           *
           * No complex code or external calls should be made in derived contracts that override this!
           */
          function _doRecoveryModeExit(
              uint256[] memory balances,
              uint256 totalSupply,
              bytes memory userData
          ) internal virtual returns (uint256, uint256[] memory) {
              uint256 bptAmountIn = userData.recoveryModeExit();
              uint256[] memory amountsOut = _computeProportionalAmountsOut(balances, totalSupply, bptAmountIn);
              return (bptAmountIn, amountsOut);
          }
          function _computeProportionalAmountsOut(
              uint256[] memory balances,
              uint256 totalSupply,
              uint256 bptAmountIn
          ) internal pure returns (uint256[] memory amountsOut) {
              /**********************************************************************************************
              // exactBPTInForTokensOut                                                                    //
              // (per token)                                                                               //
              // aO = tokenAmountOut             /        bptIn         \\                                  //
              // b = tokenBalance      a0 = b * | ---------------------  |                                 //
              // bptIn = bptAmountIn             \\     bptTotalSupply    /                                 //
              // bpt = bptTotalSupply                                                                      //
              **********************************************************************************************/
              // Since we're computing an amount out, we round down overall. This means rounding down on both the
              // multiplication and division.
              uint256 bptRatio = bptAmountIn.divDown(totalSupply);
              amountsOut = new uint256[](balances.length);
              for (uint256 i = 0; i < balances.length; i++) {
                  amountsOut[i] = balances[i].mulDown(bptRatio);
              }
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      /**
       * @dev Wrappers over Solidity's arithmetic operations with added overflow
       * checks.
       *
       * Arithmetic operations in Solidity wrap on overflow. This can easily result
       * in bugs, because programmers usually assume that an overflow raises an
       * error, which is the standard behavior in high level programming languages.
       * `SafeMath` restores this intuition by reverting the transaction when an
       * operation overflows.
       *
       * Using this library instead of the unchecked operations eliminates an entire
       * class of bugs, so it's recommended to use it always.
       */
      library SafeMath {
          /**
           * @dev Returns the addition of two unsigned integers, reverting on
           * overflow.
           *
           * Counterpart to Solidity's `+` operator.
           *
           * Requirements:
           *
           * - Addition cannot overflow.
           */
          function add(uint256 a, uint256 b) internal pure returns (uint256) {
              uint256 c = a + b;
              _require(c >= a, Errors.ADD_OVERFLOW);
              return c;
          }
          /**
           * @dev Returns the subtraction of two unsigned integers, reverting on
           * overflow (when the result is negative).
           *
           * Counterpart to Solidity's `-` operator.
           *
           * Requirements:
           *
           * - Subtraction cannot overflow.
           */
          function sub(uint256 a, uint256 b) internal pure returns (uint256) {
              return sub(a, b, Errors.SUB_OVERFLOW);
          }
          /**
           * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
           * overflow (when the result is negative).
           *
           * Counterpart to Solidity's `-` operator.
           *
           * Requirements:
           *
           * - Subtraction cannot overflow.
           */
          function sub(
              uint256 a,
              uint256 b,
              uint256 errorCode
          ) internal pure returns (uint256) {
              _require(b <= a, errorCode);
              uint256 c = a - b;
              return c;
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/openzeppelin/IERC20Permit.sol";
      import "./ERC20.sol";
      import "../helpers/EOASignaturesValidator.sol";
      /**
       * @dev Implementation of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
       * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
       *
       * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
       * presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
       * need to send a transaction, and thus is not required to hold Ether at all.
       *
       * _Available since v3.4._
       */
      abstract contract ERC20Permit is ERC20, IERC20Permit, EOASignaturesValidator {
          // solhint-disable-next-line var-name-mixedcase
          bytes32 private constant _PERMIT_TYPEHASH = keccak256(
              "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
          );
          /**
           * @dev Initializes the {EIP712} domain separator using the `name` parameter, and setting `version` to `"1"`.
           *
           * It's a good idea to use the same `name` that is defined as the ERC20 token name.
           */
          constructor(string memory name) EIP712(name, "1") {
              // solhint-disable-previous-line no-empty-blocks
          }
          /**
           * @dev See {IERC20Permit-permit}.
           */
          function permit(
              address owner,
              address spender,
              uint256 value,
              uint256 deadline,
              uint8 v,
              bytes32 r,
              bytes32 s
          ) public virtual override {
              bytes32 structHash = keccak256(
                  abi.encode(_PERMIT_TYPEHASH, owner, spender, value, getNextNonce(owner), deadline)
              );
              _ensureValidSignature(owner, structHash, _toArraySignature(v, r, s), deadline, Errors.INVALID_SIGNATURE);
              _approve(owner, spender, value);
          }
          /**
           * @dev See {IERC20Permit-nonces}.
           */
          function nonces(address owner) public view override returns (uint256) {
              return getNextNonce(owner);
          }
          /**
           * @dev See {IERC20Permit-DOMAIN_SEPARATOR}.
           */
          // solhint-disable-next-line func-name-mixedcase
          function DOMAIN_SEPARATOR() external view override returns (bytes32) {
              return getDomainSeparator();
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      /**
       * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
       * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
       *
       * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
       * presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
       * need to send a transaction, and thus is not required to hold Ether at all.
       */
      interface IERC20Permit {
          /**
           * @dev Sets `value` as the allowance of `spender` over `owner`'s tokens,
           * given `owner`'s signed approval.
           *
           * IMPORTANT: The same issues {IERC20-approve} has related to transaction
           * ordering also apply here.
           *
           * Emits an {Approval} event.
           *
           * Requirements:
           *
           * - `spender` cannot be the zero address.
           * - `deadline` must be a timestamp in the future.
           * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
           * over the EIP712-formatted function arguments.
           * - the signature must use ``owner``'s current nonce (see {nonces}).
           *
           * For more information on the signature format, see the
           * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
           * section].
           */
          function permit(
              address owner,
              address spender,
              uint256 value,
              uint256 deadline,
              uint8 v,
              bytes32 r,
              bytes32 s
          ) external;
          /**
           * @dev Returns the current nonce for `owner`. This value must be
           * included whenever a signature is generated for {permit}.
           *
           * Every successful call to {permit} increases ``owner``'s nonce by one. This
           * prevents a signature from being used multiple times.
           */
          function nonces(address owner) external view returns (uint256);
          /**
           * @dev Returns the domain separator used in the encoding of the signature for `permit`, as defined by {EIP712}.
           */
          // solhint-disable-next-line func-name-mixedcase
          function DOMAIN_SEPARATOR() external view returns (bytes32);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/ISignaturesValidator.sol";
      import "../openzeppelin/EIP712.sol";
      /**
       * @dev Utility for signing Solidity function calls.
       */
      abstract contract EOASignaturesValidator is ISignaturesValidator, EIP712 {
          // Replay attack prevention for each account.
          mapping(address => uint256) internal _nextNonce;
          function getDomainSeparator() public view override returns (bytes32) {
              return _domainSeparatorV4();
          }
          function getNextNonce(address account) public view override returns (uint256) {
              return _nextNonce[account];
          }
          function _ensureValidSignature(
              address account,
              bytes32 structHash,
              bytes memory signature,
              uint256 errorCode
          ) internal {
              return _ensureValidSignature(account, structHash, signature, type(uint256).max, errorCode);
          }
          function _ensureValidSignature(
              address account,
              bytes32 structHash,
              bytes memory signature,
              uint256 deadline,
              uint256 errorCode
          ) internal {
              bytes32 digest = _hashTypedDataV4(structHash);
              _require(_isValidSignature(account, digest, signature), errorCode);
              // We could check for the deadline before validating the signature, but this leads to saner error processing (as
              // we only care about expired deadlines if the signature is correct) and only affects the gas cost of the revert
              // scenario, which will only occur infrequently, if ever.
              // The deadline is timestamp-based: it should not be relied upon for sub-minute accuracy.
              // solhint-disable-next-line not-rely-on-time
              _require(deadline >= block.timestamp, Errors.EXPIRED_SIGNATURE);
              // We only advance the nonce after validating the signature. This is irrelevant for this module, but it can be
              // important in derived contracts that override _isValidSignature (e.g. SignaturesValidator), as we want for
              // the observable state to still have the current nonce as the next valid one.
              _nextNonce[account] += 1;
          }
          function _isValidSignature(
              address account,
              bytes32 digest,
              bytes memory signature
          ) internal view virtual returns (bool) {
              _require(signature.length == 65, Errors.MALFORMED_SIGNATURE);
              bytes32 r;
              bytes32 s;
              uint8 v;
              // ecrecover takes the r, s and v signature parameters, and the only way to get them is to use assembly.
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  r := mload(add(signature, 0x20))
                  s := mload(add(signature, 0x40))
                  v := byte(0, mload(add(signature, 0x60)))
              }
              address recoveredAddress = ecrecover(digest, v, r, s);
              // ecrecover returns the zero address on recover failure, so we need to handle that explicitly.
              return (recoveredAddress != address(0) && recoveredAddress == account);
          }
          function _toArraySignature(
              uint8 v,
              bytes32 r,
              bytes32 s
          ) internal pure returns (bytes memory) {
              bytes memory signature = new bytes(65);
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  mstore(add(signature, 32), r)
                  mstore(add(signature, 64), s)
                  mstore8(add(signature, 96), v)
              }
              return signature;
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      /**
       * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
       *
       * The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
       * thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
       * they need in their contracts using a combination of `abi.encode` and `keccak256`.
       *
       * This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
       * scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
       * ({_hashTypedDataV4}).
       *
       * The implementation of the domain separator was designed to be as efficient as possible while still properly updating
       * the chain id to protect against replay attacks on an eventual fork of the chain.
       *
       * NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
       * https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
       *
       * _Available since v3.4._
       */
      abstract contract EIP712 {
          /* solhint-disable var-name-mixedcase */
          bytes32 private immutable _HASHED_NAME;
          bytes32 private immutable _HASHED_VERSION;
          bytes32 private immutable _TYPE_HASH;
          /* solhint-enable var-name-mixedcase */
          /**
           * @dev Initializes the domain separator and parameter caches.
           *
           * The meaning of `name` and `version` is specified in
           * https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
           *
           * - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
           * - `version`: the current major version of the signing domain.
           *
           * NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
           * contract upgrade].
           */
          constructor(string memory name, string memory version) {
              _HASHED_NAME = keccak256(bytes(name));
              _HASHED_VERSION = keccak256(bytes(version));
              _TYPE_HASH = keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
          }
          /**
           * @dev Returns the domain separator for the current chain.
           */
          function _domainSeparatorV4() internal view virtual returns (bytes32) {
              return keccak256(abi.encode(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION, _getChainId(), address(this)));
          }
          /**
           * @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
           * function returns the hash of the fully encoded EIP712 message for this domain.
           *
           * This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
           *
           * ```solidity
           * bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
           *     keccak256("Mail(address to,string contents)"),
           *     mailTo,
           *     keccak256(bytes(mailContents))
           * )));
           * address signer = ECDSA.recover(digest, signature);
           * ```
           */
          function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
              return keccak256(abi.encodePacked("\\x19\\x01", _domainSeparatorV4(), structHash));
          }
          function _getChainId() private view returns (uint256 chainId) {
              // Silence state mutability warning without generating bytecode.
              // See https://github.com/ethereum/solidity/issues/10090#issuecomment-741789128 and
              // https://github.com/ethereum/solidity/issues/2691
              this;
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  chainId := chainid()
              }
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      library BasePoolUserData {
          // Special ExitKind for all pools, used in Recovery Mode. Use the max 8-bit value to prevent conflicts
          // with future additions to the ExitKind enums (or any front-end code that maps to existing values)
          uint8 public constant RECOVERY_MODE_EXIT_KIND = 255;
          // Return true if this is the special exit kind.
          function isRecoveryModeExitKind(bytes memory self) internal pure returns (bool) {
              // Check for the "no data" case, or abi.decode would revert
              return self.length > 0 && abi.decode(self, (uint8)) == RECOVERY_MODE_EXIT_KIND;
          }
          // Parse the bptAmountIn out of the userData
          function recoveryModeExit(bytes memory self) internal pure returns (uint256 bptAmountIn) {
              (, bptAmountIn) = abi.decode(self, (uint8, uint256));
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      /**
       * @dev Interface for the RecoveryMode module.
       */
      interface IRecoveryMode {
          /**
           * @dev Emitted when the Recovery Mode status changes.
           */
          event RecoveryModeStateChanged(bool enabled);
          /**
           * @notice Enables Recovery Mode in the Pool, disabling protocol fee collection and allowing for safe proportional
           * exits with low computational complexity and no dependencies.
           */
          function enableRecoveryMode() external;
          /**
           * @notice Disables Recovery Mode in the Pool, restoring protocol fee collection and disallowing proportional exits.
           */
          function disableRecoveryMode() external;
          /**
           * @notice Returns true if the Pool is in Recovery Mode.
           */
          function inRecoveryMode() external view returns (bool);
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      import "@balancer-labs/v2-interfaces/contracts/standalone-utils/IProtocolFeePercentagesProvider.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/openzeppelin/SafeCast.sol";
      import "../RecoveryMode.sol";
      /**
       * @dev The Vault does not provide the protocol swap fee percentage in swap hooks (as swaps don't typically need this
       * value), so for swaps that need this value, we would have to to fetch it ourselves from the
       * ProtocolFeePercentagesProvider. Additionally, other protocol fee types (such as Yield or AUM) can only be obtained
       * by making said call.
       *
       * However, these values change so rarely that it doesn't make sense to perform the required calls to get the current
       * values in every single user interaction. Instead, we keep a local copy that can be permissionlessly updated by anyone
       * with the real value. We also pack these values together, performing a single storage read to get them all.
       *
       * When initialized with a special sentinel value, the swap fee is delegated, meaning the mutable protocol swap fee
       * cache is set to the current value stored in the ProtocolFeePercentagesProvider, and can be updated by anyone with a
       * call to `updateProtocolFeePercentageCache`. Any other value means the protocol swap fee is fixed, so it is instead
       * stored in the immutable `_fixedProtocolSwapFeePercentage`.
       */
      abstract contract ProtocolFeeCache is RecoveryMode {
          using SafeCast for uint256;
          IProtocolFeePercentagesProvider private immutable _protocolFeeProvider;
          // Protocol Fee Percentages can never be larger than 100% (1e18), which fits in ~59 bits, so using 64 for each type
          // is sufficient.
          struct FeeTypeCache {
              uint64 swapFee;
              uint64 yieldFee;
              uint64 aumFee;
          }
          FeeTypeCache private _cache;
          event ProtocolFeePercentageCacheUpdated(uint256 indexed feeType, uint256 protocolFeePercentage);
          // Swap fees can be set to a fixed value at construction, or delegated to the ProtocolFeePercentagesProvider if
          // passing the special sentinel value.
          uint256 public constant DELEGATE_PROTOCOL_SWAP_FEES_SENTINEL = type(uint256).max;
          bool private immutable _delegatedProtocolSwapFees;
          // Only valid when `_delegatedProtocolSwapFees` is false
          uint256 private immutable _fixedProtocolSwapFeePercentage;
          constructor(IProtocolFeePercentagesProvider protocolFeeProvider, uint256 protocolSwapFeePercentage) {
              // Protocol swap fees are delegated to the value reported by the ProtocolFeePercentagesProvider if the sentinel
              // value is passed.
              bool delegatedProtocolSwapFees = protocolSwapFeePercentage == DELEGATE_PROTOCOL_SWAP_FEES_SENTINEL;
              _delegatedProtocolSwapFees = delegatedProtocolSwapFees;
              _protocolFeeProvider = protocolFeeProvider;
              _updateProtocolFeeCache(protocolFeeProvider, ProtocolFeeType.YIELD);
              _updateProtocolFeeCache(protocolFeeProvider, ProtocolFeeType.AUM);
              if (delegatedProtocolSwapFees) {
                  _updateProtocolFeeCache(protocolFeeProvider, ProtocolFeeType.SWAP);
              } else {
                  _require(
                      protocolSwapFeePercentage <= protocolFeeProvider.getFeeTypeMaximumPercentage(ProtocolFeeType.SWAP),
                      Errors.SWAP_FEE_PERCENTAGE_TOO_HIGH
                  );
                  // We cannot set `_fixedProtocolSwapFeePercentage` here due to it being immutable so instead we must set it
                  // in the main function scope with a value based on whether protocol fees are delegated.
                  // Emit an event as we do in `_updateProtocolFeeCache` to appear the same to offchain indexers.
                  emit ProtocolFeePercentageCacheUpdated(ProtocolFeeType.SWAP, protocolSwapFeePercentage);
              }
              // As `_fixedProtocolSwapFeePercentage` is immutable we must set a value, but just set to zero if it's not used.
              _fixedProtocolSwapFeePercentage = delegatedProtocolSwapFees ? 0 : protocolSwapFeePercentage;
          }
          /**
           * @dev Returns the cached protocol fee percentage. If `getProtocolSwapFeeDelegation()` is false, this value is
           * immutable for swap fee queries. Alternatively, it will track the global fee percentage set in the
           * ProtocolFeePercentagesProvider.
           */
          function getProtocolFeePercentageCache(uint256 feeType) public view returns (uint256) {
              if (inRecoveryMode()) {
                  return 0;
              }
              if (feeType == ProtocolFeeType.SWAP) {
                  return getProtocolSwapFeeDelegation() ? _cache.swapFee : _fixedProtocolSwapFeePercentage;
              } else if (feeType == ProtocolFeeType.YIELD) {
                  return _cache.yieldFee;
              } else if (feeType == ProtocolFeeType.AUM) {
                  return _cache.aumFee;
              } else {
                  _revert(Errors.UNHANDLED_FEE_TYPE);
              }
          }
          /**
           * @dev Can be called by anyone to update the cached fee percentages (swap fee is only updated when delegated).
           * Updates the cache to the latest value set by governance.
           *
           * This function will revert when called within a Vault context (i.e. in the middle of a join or an exit).
           *
           * This function depends on the invariant value, which may be calculated incorrectly in the middle of a join or
           * an exit, because the state of the pool could be out of sync with the state of the Vault.
           * `_beforeProtocolFeeCacheUpdate` will revert when called from such a context for composable stable pools,
           * effectively protecting this function.
           *
           * See https://forum.balancer.fi/t/reentrancy-vulnerability-scope-expanded/4345 for reference.
           */
          function updateProtocolFeePercentageCache() external {
              _beforeProtocolFeeCacheUpdate();
              if (getProtocolSwapFeeDelegation()) {
                  _updateProtocolFeeCache(_protocolFeeProvider, ProtocolFeeType.SWAP);
              }
              _updateProtocolFeeCache(_protocolFeeProvider, ProtocolFeeType.YIELD);
              _updateProtocolFeeCache(_protocolFeeProvider, ProtocolFeeType.AUM);
          }
          /**
           * @dev Override in derived contracts to perform some action before the cache is updated. This is typically relevant
           * to Pools that incur protocol debt between operations. To avoid altering the amount due retroactively, this debt
           * needs to be paid before the fee percentages change.
           */
          function _beforeProtocolFeeCacheUpdate() internal virtual {}
          /**
           * @dev Returns whether this Pool tracks protocol swap fee changes in the IProtocolFeePercentagesProvider.
           */
          function getProtocolSwapFeeDelegation() public view returns (bool) {
              return _delegatedProtocolSwapFees;
          }
          function _updateProtocolFeeCache(IProtocolFeePercentagesProvider protocolFeeProvider, uint256 feeType) private {
              uint256 currentValue = protocolFeeProvider.getFeeTypePercentage(feeType);
              if (feeType == ProtocolFeeType.SWAP) {
                  _cache.swapFee = currentValue.toUint64();
              } else if (feeType == ProtocolFeeType.YIELD) {
                  _cache.yieldFee = currentValue.toUint64();
              } else if (feeType == ProtocolFeeType.AUM) {
                  _cache.aumFee = currentValue.toUint64();
              } else {
                  _revert(Errors.UNHANDLED_FEE_TYPE);
              }
              emit ProtocolFeePercentageCacheUpdated(feeType, currentValue);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-solidity-utils/contracts/math/FixedPoint.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/math/Math.sol";
      import "./ProtocolFees.sol";
      library InvariantGrowthProtocolSwapFees {
          using FixedPoint for uint256;
          function getProtocolOwnershipPercentage(
              uint256 invariantGrowthRatio,
              uint256 supplyGrowthRatio,
              uint256 protocolSwapFeePercentage
          ) internal pure returns (uint256) {
              // Joins and exits are symmetrical; for simplicity, we consider a join, where the invariant and supply
              // both increase.
              // |-------------------------|-- original invariant * invariantGrowthRatio
              // |   increase from fees    |
              // |-------------------------|-- original invariant * supply growth ratio (fee-less invariant)
              // |                         |
              // | increase from balances  |
              // |-------------------------|-- original invariant
              // |                         |
              // |                         |  |------------------|-- currentSupply
              // |                         |  |    BPT minted    |
              // |                         |  |------------------|-- previousSupply
              // |   original invariant    |  |  original supply |
              // |_________________________|  |__________________|
              //
              // If the join is proportional, the invariant and supply will likewise increase proportionally,
              // so the growth ratios (invariantGrowthRatio / supplyGrowthRatio) will be equal. In this case, we do not charge
              // any protocol fees.
              // We also charge no protocol fees in the case where `invariantGrowthRatio < supplyGrowthRatio` to avoid
              // potential underflows, however this should only occur in extremely low volume actions due solely to rounding
              // error.
              if ((supplyGrowthRatio >= invariantGrowthRatio) || (protocolSwapFeePercentage == 0)) return 0;
              // If the join is non-proportional, the supply increase will be proportionally less than the invariant increase,
              // since the BPT minted will be based on fewer tokens (because swap fees are not included). So the supply growth
              // is due entirely to the balance changes, while the invariant growth also includes swap fees.
              //
              // To isolate the amount of increase by fees then, we multiply the original invariant by the supply growth
              // ratio to get the "feeless invariant". The difference between the final invariant and this value is then
              // the amount of the invariant due to fees, which we convert to a percentage by normalizing against the
              // final invariant. This is expressed as the expression below:
              //
              // invariantGrowthFromFees = currentInvariant - supplyGrowthRatio * previousInvariant
              //
              // We then divide through by current invariant so the LHS can be identified as the fraction of the pool which
              // is made up of accumulated swap fees.
              //
              // swapFeesPercentage = 1 - supplyGrowthRatio * previousInvariant / currentInvariant
              //
              // We then define `invariantGrowthRatio` in a similar fashion to `supplyGrowthRatio` to give the result:
              //
              // swapFeesPercentage = 1 - supplyGrowthRatio / invariantGrowthRatio
              //
              // Using this form allows us to consider only the ratios of the two invariants, rather than their absolute
              // values: a useful property, as this is sometimes easier than calculating the full invariant twice.
              // We've already checked that `supplyGrowthRatio` is smaller than `invariantGrowthRatio`, and hence their ratio
              // smaller than FixedPoint.ONE, allowing for unchecked arithmetic.
              uint256 swapFeesPercentage = FixedPoint.ONE - supplyGrowthRatio.divDown(invariantGrowthRatio);
              // We then multiply by the protocol swap fee percentage to get the fraction of the pool which the protocol
              // should own once fees have been collected.
              return swapFeesPercentage.mulDown(protocolSwapFeePercentage);
          }
          function calcDueProtocolFees(
              uint256 invariantGrowthRatio,
              uint256 previousSupply,
              uint256 currentSupply,
              uint256 protocolSwapFeePercentage
          ) internal pure returns (uint256) {
              uint256 protocolOwnershipPercentage = getProtocolOwnershipPercentage(
                  invariantGrowthRatio,
                  currentSupply.divDown(previousSupply),
                  protocolSwapFeePercentage
              );
              return ProtocolFees.bptForPoolOwnershipPercentage(currentSupply, protocolOwnershipPercentage);
          }
      }
      // SPDX-License-Identifier: MIT
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-interfaces/contracts/solidity-utils/helpers/BalancerErrors.sol";
      /**
       * @dev Wrappers over Solidity's uintXX/intXX casting operators with added overflow
       * checks.
       *
       * Downcasting from uint256/int256 in Solidity does not revert on overflow. This can
       * easily result in undesired exploitation or bugs, since developers usually
       * assume that overflows raise errors. `SafeCast` restores this intuition by
       * reverting the transaction when such an operation overflows.
       *
       * Using this library instead of the unchecked operations eliminates an entire
       * class of bugs, so it's recommended to use it always.
       *
       * Can be combined with {SafeMath} and {SignedSafeMath} to extend it to smaller types, by performing
       * all math on `uint256` and `int256` and then downcasting.
       */
      library SafeCast {
          /**
           * @dev Converts an unsigned uint256 into a signed int256.
           *
           * Requirements:
           *
           * - input must be less than or equal to maxInt256.
           */
          function toInt256(uint256 value) internal pure returns (int256) {
              _require(value >> 255 == 0, Errors.SAFE_CAST_VALUE_CANT_FIT_INT256);
              return int256(value);
          }
          /**
           * @dev Converts an unsigned uint256 into an unsigned uint64.
           *
           * Requirements:
           *
           * - input must be less than or equal to maxUint64.
           */
          function toUint64(uint256 value) internal pure returns (uint64) {
              _require(value <= type(uint64).max, Errors.SAFE_CAST_VALUE_CANT_FIT_UINT64);
              return uint64(value);
          }
      }
      // SPDX-License-Identifier: GPL-3.0-or-later
      // This program is free software: you can redistribute it and/or modify
      // it under the terms of the GNU General Public License as published by
      // the Free Software Foundation, either version 3 of the License, or
      // (at your option) any later version.
      // This program is distributed in the hope that it will be useful,
      // but WITHOUT ANY WARRANTY; without even the implied warranty of
      // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      // GNU General Public License for more details.
      // You should have received a copy of the GNU General Public License
      // along with this program.  If not, see <http://www.gnu.org/licenses/>.
      pragma solidity ^0.7.0;
      import "@balancer-labs/v2-solidity-utils/contracts/math/FixedPoint.sol";
      import "@balancer-labs/v2-solidity-utils/contracts/math/Math.sol";
      library ProtocolFees {
          using FixedPoint for uint256;
          /**
           * @dev Calculates the amount of BPT necessary to give ownership of a given percentage of the Pool.
           * Note that this function reverts if `poolPercentage` >= 100%, it's expected that the caller will enforce this.
           * @param totalSupply - The total supply of the pool prior to minting BPT.
           * @param poolOwnershipPercentage - The desired ownership percentage of the pool to have as a result of minting BPT.
           * @return bptAmount - The amount of BPT to mint such that it is `poolPercentage` of the resultant total supply.
           */
          function bptForPoolOwnershipPercentage(uint256 totalSupply, uint256 poolOwnershipPercentage)
              internal
              pure
              returns (uint256)
          {
              // If we mint some amount `bptAmount` of BPT then the percentage ownership of the pool this grants is given by:
              // `poolOwnershipPercentage = bptAmount / (totalSupply + bptAmount)`.
              // Solving for `bptAmount`, we arrive at:
              // `bptAmount = totalSupply * poolOwnershipPercentage / (1 - poolOwnershipPercentage)`.
              return Math.divDown(Math.mul(totalSupply, poolOwnershipPercentage), poolOwnershipPercentage.complement());
          }
      }
      

      File 4 of 5: TransparentUpgradeableProxy
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.5.0-rc.0) (interfaces/draft-IERC1822.sol)
      pragma solidity ^0.8.0;
      /**
       * @dev ERC1822: Universal Upgradeable Proxy Standard (UUPS) documents a method for upgradeability through a simplified
       * proxy whose upgrades are fully controlled by the current implementation.
       */
      interface IERC1822Proxiable {
          /**
           * @dev Returns the storage slot that the proxiable contract assumes is being used to store the implementation
           * address.
           *
           * IMPORTANT: A proxy pointing at a proxiable contract should not be considered proxiable itself, because this risks
           * bricking a proxy that upgrades to it, by delegating to itself until out of gas. Thus it is critical that this
           * function revert if invoked through a proxy.
           */
          function proxiableUUID() external view returns (bytes32);
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts v4.4.1 (proxy/ERC1967/ERC1967Proxy.sol)
      pragma solidity ^0.8.0;
      import "../Proxy.sol";
      import "./ERC1967Upgrade.sol";
      /**
       * @dev This contract implements an upgradeable proxy. It is upgradeable because calls are delegated to an
       * implementation address that can be changed. This address is stored in storage in the location specified by
       * https://eips.ethereum.org/EIPS/eip-1967[EIP1967], so that it doesn't conflict with the storage layout of the
       * implementation behind the proxy.
       */
      contract ERC1967Proxy is Proxy, ERC1967Upgrade {
          /**
           * @dev Initializes the upgradeable proxy with an initial implementation specified by `_logic`.
           *
           * If `_data` is nonempty, it's used as data in a delegate call to `_logic`. This will typically be an encoded
           * function call, and allows initializating the storage of the proxy like a Solidity constructor.
           */
          constructor(address _logic, bytes memory _data) payable {
              assert(_IMPLEMENTATION_SLOT == bytes32(uint256(keccak256("eip1967.proxy.implementation")) - 1));
              _upgradeToAndCall(_logic, _data, false);
          }
          /**
           * @dev Returns the current implementation address.
           */
          function _implementation() internal view virtual override returns (address impl) {
              return ERC1967Upgrade._getImplementation();
          }
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.5.0-rc.0) (proxy/ERC1967/ERC1967Upgrade.sol)
      pragma solidity ^0.8.2;
      import "../beacon/IBeacon.sol";
      import "../../interfaces/draft-IERC1822.sol";
      import "../../utils/Address.sol";
      import "../../utils/StorageSlot.sol";
      /**
       * @dev This abstract contract provides getters and event emitting update functions for
       * https://eips.ethereum.org/EIPS/eip-1967[EIP1967] slots.
       *
       * _Available since v4.1._
       *
       * @custom:oz-upgrades-unsafe-allow delegatecall
       */
      abstract contract ERC1967Upgrade {
          // This is the keccak-256 hash of "eip1967.proxy.rollback" subtracted by 1
          bytes32 private constant _ROLLBACK_SLOT = 0x4910fdfa16fed3260ed0e7147f7cc6da11a60208b5b9406d12a635614ffd9143;
          /**
           * @dev Storage slot with the address of the current implementation.
           * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
           * validated in the constructor.
           */
          bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
          /**
           * @dev Emitted when the implementation is upgraded.
           */
          event Upgraded(address indexed implementation);
          /**
           * @dev Returns the current implementation address.
           */
          function _getImplementation() internal view returns (address) {
              return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
          }
          /**
           * @dev Stores a new address in the EIP1967 implementation slot.
           */
          function _setImplementation(address newImplementation) private {
              require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
              StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
          }
          /**
           * @dev Perform implementation upgrade
           *
           * Emits an {Upgraded} event.
           */
          function _upgradeTo(address newImplementation) internal {
              _setImplementation(newImplementation);
              emit Upgraded(newImplementation);
          }
          /**
           * @dev Perform implementation upgrade with additional setup call.
           *
           * Emits an {Upgraded} event.
           */
          function _upgradeToAndCall(
              address newImplementation,
              bytes memory data,
              bool forceCall
          ) internal {
              _upgradeTo(newImplementation);
              if (data.length > 0 || forceCall) {
                  Address.functionDelegateCall(newImplementation, data);
              }
          }
          /**
           * @dev Perform implementation upgrade with security checks for UUPS proxies, and additional setup call.
           *
           * Emits an {Upgraded} event.
           */
          function _upgradeToAndCallUUPS(
              address newImplementation,
              bytes memory data,
              bool forceCall
          ) internal {
              // Upgrades from old implementations will perform a rollback test. This test requires the new
              // implementation to upgrade back to the old, non-ERC1822 compliant, implementation. Removing
              // this special case will break upgrade paths from old UUPS implementation to new ones.
              if (StorageSlot.getBooleanSlot(_ROLLBACK_SLOT).value) {
                  _setImplementation(newImplementation);
              } else {
                  try IERC1822Proxiable(newImplementation).proxiableUUID() returns (bytes32 slot) {
                      require(slot == _IMPLEMENTATION_SLOT, "ERC1967Upgrade: unsupported proxiableUUID");
                  } catch {
                      revert("ERC1967Upgrade: new implementation is not UUPS");
                  }
                  _upgradeToAndCall(newImplementation, data, forceCall);
              }
          }
          /**
           * @dev Storage slot with the admin of the contract.
           * This is the keccak-256 hash of "eip1967.proxy.admin" subtracted by 1, and is
           * validated in the constructor.
           */
          bytes32 internal constant _ADMIN_SLOT = 0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103;
          /**
           * @dev Emitted when the admin account has changed.
           */
          event AdminChanged(address previousAdmin, address newAdmin);
          /**
           * @dev Returns the current admin.
           */
          function _getAdmin() internal view virtual returns (address) {
              return StorageSlot.getAddressSlot(_ADMIN_SLOT).value;
          }
          /**
           * @dev Stores a new address in the EIP1967 admin slot.
           */
          function _setAdmin(address newAdmin) private {
              require(newAdmin != address(0), "ERC1967: new admin is the zero address");
              StorageSlot.getAddressSlot(_ADMIN_SLOT).value = newAdmin;
          }
          /**
           * @dev Changes the admin of the proxy.
           *
           * Emits an {AdminChanged} event.
           */
          function _changeAdmin(address newAdmin) internal {
              emit AdminChanged(_getAdmin(), newAdmin);
              _setAdmin(newAdmin);
          }
          /**
           * @dev The storage slot of the UpgradeableBeacon contract which defines the implementation for this proxy.
           * This is bytes32(uint256(keccak256('eip1967.proxy.beacon')) - 1)) and is validated in the constructor.
           */
          bytes32 internal constant _BEACON_SLOT = 0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50;
          /**
           * @dev Emitted when the beacon is upgraded.
           */
          event BeaconUpgraded(address indexed beacon);
          /**
           * @dev Returns the current beacon.
           */
          function _getBeacon() internal view returns (address) {
              return StorageSlot.getAddressSlot(_BEACON_SLOT).value;
          }
          /**
           * @dev Stores a new beacon in the EIP1967 beacon slot.
           */
          function _setBeacon(address newBeacon) private {
              require(Address.isContract(newBeacon), "ERC1967: new beacon is not a contract");
              require(Address.isContract(IBeacon(newBeacon).implementation()), "ERC1967: beacon implementation is not a contract");
              StorageSlot.getAddressSlot(_BEACON_SLOT).value = newBeacon;
          }
          /**
           * @dev Perform beacon upgrade with additional setup call. Note: This upgrades the address of the beacon, it does
           * not upgrade the implementation contained in the beacon (see {UpgradeableBeacon-_setImplementation} for that).
           *
           * Emits a {BeaconUpgraded} event.
           */
          function _upgradeBeaconToAndCall(
              address newBeacon,
              bytes memory data,
              bool forceCall
          ) internal {
              _setBeacon(newBeacon);
              emit BeaconUpgraded(newBeacon);
              if (data.length > 0 || forceCall) {
                  Address.functionDelegateCall(IBeacon(newBeacon).implementation(), data);
              }
          }
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.5.0-rc.0) (proxy/Proxy.sol)
      pragma solidity ^0.8.0;
      /**
       * @dev This abstract contract provides a fallback function that delegates all calls to another contract using the EVM
       * instruction `delegatecall`. We refer to the second contract as the _implementation_ behind the proxy, and it has to
       * be specified by overriding the virtual {_implementation} function.
       *
       * Additionally, delegation to the implementation can be triggered manually through the {_fallback} function, or to a
       * different contract through the {_delegate} function.
       *
       * The success and return data of the delegated call will be returned back to the caller of the proxy.
       */
      abstract contract Proxy {
          /**
           * @dev Delegates the current call to `implementation`.
           *
           * This function does not return to its internal call site, it will return directly to the external caller.
           */
          function _delegate(address implementation) internal virtual {
              assembly {
                  // Copy msg.data. We take full control of memory in this inline assembly
                  // block because it will not return to Solidity code. We overwrite the
                  // Solidity scratch pad at memory position 0.
                  calldatacopy(0, 0, calldatasize())
                  // Call the implementation.
                  // out and outsize are 0 because we don't know the size yet.
                  let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
                  // Copy the returned data.
                  returndatacopy(0, 0, returndatasize())
                  switch result
                  // delegatecall returns 0 on error.
                  case 0 {
                      revert(0, returndatasize())
                  }
                  default {
                      return(0, returndatasize())
                  }
              }
          }
          /**
           * @dev This is a virtual function that should be overriden so it returns the address to which the fallback function
           * and {_fallback} should delegate.
           */
          function _implementation() internal view virtual returns (address);
          /**
           * @dev Delegates the current call to the address returned by `_implementation()`.
           *
           * This function does not return to its internall call site, it will return directly to the external caller.
           */
          function _fallback() internal virtual {
              _beforeFallback();
              _delegate(_implementation());
          }
          /**
           * @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if no other
           * function in the contract matches the call data.
           */
          fallback() external payable virtual {
              _fallback();
          }
          /**
           * @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if call data
           * is empty.
           */
          receive() external payable virtual {
              _fallback();
          }
          /**
           * @dev Hook that is called before falling back to the implementation. Can happen as part of a manual `_fallback`
           * call, or as part of the Solidity `fallback` or `receive` functions.
           *
           * If overriden should call `super._beforeFallback()`.
           */
          function _beforeFallback() internal virtual {}
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts v4.4.1 (proxy/beacon/IBeacon.sol)
      pragma solidity ^0.8.0;
      /**
       * @dev This is the interface that {BeaconProxy} expects of its beacon.
       */
      interface IBeacon {
          /**
           * @dev Must return an address that can be used as a delegate call target.
           *
           * {BeaconProxy} will check that this address is a contract.
           */
          function implementation() external view returns (address);
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts v4.4.1 (proxy/transparent/TransparentUpgradeableProxy.sol)
      pragma solidity ^0.8.0;
      import "../ERC1967/ERC1967Proxy.sol";
      /**
       * @dev This contract implements a proxy that is upgradeable by an admin.
       *
       * To avoid https://medium.com/nomic-labs-blog/malicious-backdoors-in-ethereum-proxies-62629adf3357[proxy selector
       * clashing], which can potentially be used in an attack, this contract uses the
       * https://blog.openzeppelin.com/the-transparent-proxy-pattern/[transparent proxy pattern]. This pattern implies two
       * things that go hand in hand:
       *
       * 1. If any account other than the admin calls the proxy, the call will be forwarded to the implementation, even if
       * that call matches one of the admin functions exposed by the proxy itself.
       * 2. If the admin calls the proxy, it can access the admin functions, but its calls will never be forwarded to the
       * implementation. If the admin tries to call a function on the implementation it will fail with an error that says
       * "admin cannot fallback to proxy target".
       *
       * These properties mean that the admin account can only be used for admin actions like upgrading the proxy or changing
       * the admin, so it's best if it's a dedicated account that is not used for anything else. This will avoid headaches due
       * to sudden errors when trying to call a function from the proxy implementation.
       *
       * Our recommendation is for the dedicated account to be an instance of the {ProxyAdmin} contract. If set up this way,
       * you should think of the `ProxyAdmin` instance as the real administrative interface of your proxy.
       */
      contract TransparentUpgradeableProxy is ERC1967Proxy {
          /**
           * @dev Initializes an upgradeable proxy managed by `_admin`, backed by the implementation at `_logic`, and
           * optionally initialized with `_data` as explained in {ERC1967Proxy-constructor}.
           */
          constructor(
              address _logic,
              address admin_,
              bytes memory _data
          ) payable ERC1967Proxy(_logic, _data) {
              assert(_ADMIN_SLOT == bytes32(uint256(keccak256("eip1967.proxy.admin")) - 1));
              _changeAdmin(admin_);
          }
          /**
           * @dev Modifier used internally that will delegate the call to the implementation unless the sender is the admin.
           */
          modifier ifAdmin() {
              if (msg.sender == _getAdmin()) {
                  _;
              } else {
                  _fallback();
              }
          }
          /**
           * @dev Returns the current admin.
           *
           * NOTE: Only the admin can call this function. See {ProxyAdmin-getProxyAdmin}.
           *
           * TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the
           * https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call.
           * `0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103`
           */
          function admin() external ifAdmin returns (address admin_) {
              admin_ = _getAdmin();
          }
          /**
           * @dev Returns the current implementation.
           *
           * NOTE: Only the admin can call this function. See {ProxyAdmin-getProxyImplementation}.
           *
           * TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the
           * https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call.
           * `0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc`
           */
          function implementation() external ifAdmin returns (address implementation_) {
              implementation_ = _implementation();
          }
          /**
           * @dev Changes the admin of the proxy.
           *
           * Emits an {AdminChanged} event.
           *
           * NOTE: Only the admin can call this function. See {ProxyAdmin-changeProxyAdmin}.
           */
          function changeAdmin(address newAdmin) external virtual ifAdmin {
              _changeAdmin(newAdmin);
          }
          /**
           * @dev Upgrade the implementation of the proxy.
           *
           * NOTE: Only the admin can call this function. See {ProxyAdmin-upgrade}.
           */
          function upgradeTo(address newImplementation) external ifAdmin {
              _upgradeToAndCall(newImplementation, bytes(""), false);
          }
          /**
           * @dev Upgrade the implementation of the proxy, and then call a function from the new implementation as specified
           * by `data`, which should be an encoded function call. This is useful to initialize new storage variables in the
           * proxied contract.
           *
           * NOTE: Only the admin can call this function. See {ProxyAdmin-upgradeAndCall}.
           */
          function upgradeToAndCall(address newImplementation, bytes calldata data) external payable ifAdmin {
              _upgradeToAndCall(newImplementation, data, true);
          }
          /**
           * @dev Returns the current admin.
           */
          function _admin() internal view virtual returns (address) {
              return _getAdmin();
          }
          /**
           * @dev Makes sure the admin cannot access the fallback function. See {Proxy-_beforeFallback}.
           */
          function _beforeFallback() internal virtual override {
              require(msg.sender != _getAdmin(), "TransparentUpgradeableProxy: admin cannot fallback to proxy target");
              super._beforeFallback();
          }
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.5.0-rc.0) (utils/Address.sol)
      pragma solidity ^0.8.1;
      /**
       * @dev Collection of functions related to the address type
       */
      library Address {
          /**
           * @dev Returns true if `account` is a contract.
           *
           * [IMPORTANT]
           * ====
           * It is unsafe to assume that an address for which this function returns
           * false is an externally-owned account (EOA) and not a contract.
           *
           * Among others, `isContract` will return false for the following
           * types of addresses:
           *
           *  - an externally-owned account
           *  - a contract in construction
           *  - an address where a contract will be created
           *  - an address where a contract lived, but was destroyed
           * ====
           *
           * [IMPORTANT]
           * ====
           * You shouldn't rely on `isContract` to protect against flash loan attacks!
           *
           * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
           * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
           * constructor.
           * ====
           */
          function isContract(address account) internal view returns (bool) {
              // This method relies on extcodesize/address.code.length, which returns 0
              // for contracts in construction, since the code is only stored at the end
              // of the constructor execution.
              return account.code.length > 0;
          }
          /**
           * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
           * `recipient`, forwarding all available gas and reverting on errors.
           *
           * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
           * of certain opcodes, possibly making contracts go over the 2300 gas limit
           * imposed by `transfer`, making them unable to receive funds via
           * `transfer`. {sendValue} removes this limitation.
           *
           * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
           *
           * IMPORTANT: because control is transferred to `recipient`, care must be
           * taken to not create reentrancy vulnerabilities. Consider using
           * {ReentrancyGuard} or the
           * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
           */
          function sendValue(address payable recipient, uint256 amount) internal {
              require(address(this).balance >= amount, "Address: insufficient balance");
              (bool success, ) = recipient.call{value: amount}("");
              require(success, "Address: unable to send value, recipient may have reverted");
          }
          /**
           * @dev Performs a Solidity function call using a low level `call`. A
           * plain `call` is an unsafe replacement for a function call: use this
           * function instead.
           *
           * If `target` reverts with a revert reason, it is bubbled up by this
           * function (like regular Solidity function calls).
           *
           * Returns the raw returned data. To convert to the expected return value,
           * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
           *
           * Requirements:
           *
           * - `target` must be a contract.
           * - calling `target` with `data` must not revert.
           *
           * _Available since v3.1._
           */
          function functionCall(address target, bytes memory data) internal returns (bytes memory) {
              return functionCall(target, data, "Address: low-level call failed");
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
           * `errorMessage` as a fallback revert reason when `target` reverts.
           *
           * _Available since v3.1._
           */
          function functionCall(
              address target,
              bytes memory data,
              string memory errorMessage
          ) internal returns (bytes memory) {
              return functionCallWithValue(target, data, 0, errorMessage);
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
           * but also transferring `value` wei to `target`.
           *
           * Requirements:
           *
           * - the calling contract must have an ETH balance of at least `value`.
           * - the called Solidity function must be `payable`.
           *
           * _Available since v3.1._
           */
          function functionCallWithValue(
              address target,
              bytes memory data,
              uint256 value
          ) internal returns (bytes memory) {
              return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
          }
          /**
           * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
           * with `errorMessage` as a fallback revert reason when `target` reverts.
           *
           * _Available since v3.1._
           */
          function functionCallWithValue(
              address target,
              bytes memory data,
              uint256 value,
              string memory errorMessage
          ) internal returns (bytes memory) {
              require(address(this).balance >= value, "Address: insufficient balance for call");
              require(isContract(target), "Address: call to non-contract");
              (bool success, bytes memory returndata) = target.call{value: value}(data);
              return verifyCallResult(success, returndata, errorMessage);
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
           * but performing a static call.
           *
           * _Available since v3.3._
           */
          function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
              return functionStaticCall(target, data, "Address: low-level static call failed");
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
           * but performing a static call.
           *
           * _Available since v3.3._
           */
          function functionStaticCall(
              address target,
              bytes memory data,
              string memory errorMessage
          ) internal view returns (bytes memory) {
              require(isContract(target), "Address: static call to non-contract");
              (bool success, bytes memory returndata) = target.staticcall(data);
              return verifyCallResult(success, returndata, errorMessage);
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
           * but performing a delegate call.
           *
           * _Available since v3.4._
           */
          function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
              return functionDelegateCall(target, data, "Address: low-level delegate call failed");
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
           * but performing a delegate call.
           *
           * _Available since v3.4._
           */
          function functionDelegateCall(
              address target,
              bytes memory data,
              string memory errorMessage
          ) internal returns (bytes memory) {
              require(isContract(target), "Address: delegate call to non-contract");
              (bool success, bytes memory returndata) = target.delegatecall(data);
              return verifyCallResult(success, returndata, errorMessage);
          }
          /**
           * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
           * revert reason using the provided one.
           *
           * _Available since v4.3._
           */
          function verifyCallResult(
              bool success,
              bytes memory returndata,
              string memory errorMessage
          ) internal pure returns (bytes memory) {
              if (success) {
                  return returndata;
              } else {
                  // Look for revert reason and bubble it up if present
                  if (returndata.length > 0) {
                      // The easiest way to bubble the revert reason is using memory via assembly
                      assembly {
                          let returndata_size := mload(returndata)
                          revert(add(32, returndata), returndata_size)
                      }
                  } else {
                      revert(errorMessage);
                  }
              }
          }
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts v4.4.1 (utils/StorageSlot.sol)
      pragma solidity ^0.8.0;
      /**
       * @dev Library for reading and writing primitive types to specific storage slots.
       *
       * Storage slots are often used to avoid storage conflict when dealing with upgradeable contracts.
       * This library helps with reading and writing to such slots without the need for inline assembly.
       *
       * The functions in this library return Slot structs that contain a `value` member that can be used to read or write.
       *
       * Example usage to set ERC1967 implementation slot:
       * ```
       * contract ERC1967 {
       *     bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
       *
       *     function _getImplementation() internal view returns (address) {
       *         return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
       *     }
       *
       *     function _setImplementation(address newImplementation) internal {
       *         require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
       *         StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
       *     }
       * }
       * ```
       *
       * _Available since v4.1 for `address`, `bool`, `bytes32`, and `uint256`._
       */
      library StorageSlot {
          struct AddressSlot {
              address value;
          }
          struct BooleanSlot {
              bool value;
          }
          struct Bytes32Slot {
              bytes32 value;
          }
          struct Uint256Slot {
              uint256 value;
          }
          /**
           * @dev Returns an `AddressSlot` with member `value` located at `slot`.
           */
          function getAddressSlot(bytes32 slot) internal pure returns (AddressSlot storage r) {
              assembly {
                  r.slot := slot
              }
          }
          /**
           * @dev Returns an `BooleanSlot` with member `value` located at `slot`.
           */
          function getBooleanSlot(bytes32 slot) internal pure returns (BooleanSlot storage r) {
              assembly {
                  r.slot := slot
              }
          }
          /**
           * @dev Returns an `Bytes32Slot` with member `value` located at `slot`.
           */
          function getBytes32Slot(bytes32 slot) internal pure returns (Bytes32Slot storage r) {
              assembly {
                  r.slot := slot
              }
          }
          /**
           * @dev Returns an `Uint256Slot` with member `value` located at `slot`.
           */
          function getUint256Slot(bytes32 slot) internal pure returns (Uint256Slot storage r) {
              assembly {
                  r.slot := slot
              }
          }
      }
      

      File 5 of 5: EzEthToken
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.9.0) (proxy/utils/Initializable.sol)
      pragma solidity ^0.8.2;
      import "../../utils/AddressUpgradeable.sol";
      /**
       * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
       * behind a proxy. Since proxied contracts do not make use of a constructor, it's common to move constructor logic to an
       * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
       * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
       *
       * The initialization functions use a version number. Once a version number is used, it is consumed and cannot be
       * reused. This mechanism prevents re-execution of each "step" but allows the creation of new initialization steps in
       * case an upgrade adds a module that needs to be initialized.
       *
       * For example:
       *
       * [.hljs-theme-light.nopadding]
       * ```solidity
       * contract MyToken is ERC20Upgradeable {
       *     function initialize() initializer public {
       *         __ERC20_init("MyToken", "MTK");
       *     }
       * }
       *
       * contract MyTokenV2 is MyToken, ERC20PermitUpgradeable {
       *     function initializeV2() reinitializer(2) public {
       *         __ERC20Permit_init("MyToken");
       *     }
       * }
       * ```
       *
       * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
       * possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.
       *
       * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
       * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
       *
       * [CAUTION]
       * ====
       * Avoid leaving a contract uninitialized.
       *
       * An uninitialized contract can be taken over by an attacker. This applies to both a proxy and its implementation
       * contract, which may impact the proxy. To prevent the implementation contract from being used, you should invoke
       * the {_disableInitializers} function in the constructor to automatically lock it when it is deployed:
       *
       * [.hljs-theme-light.nopadding]
       * ```
       * /// @custom:oz-upgrades-unsafe-allow constructor
       * constructor() {
       *     _disableInitializers();
       * }
       * ```
       * ====
       */
      abstract contract Initializable {
          /**
           * @dev Indicates that the contract has been initialized.
           * @custom:oz-retyped-from bool
           */
          uint8 private _initialized;
          /**
           * @dev Indicates that the contract is in the process of being initialized.
           */
          bool private _initializing;
          /**
           * @dev Triggered when the contract has been initialized or reinitialized.
           */
          event Initialized(uint8 version);
          /**
           * @dev A modifier that defines a protected initializer function that can be invoked at most once. In its scope,
           * `onlyInitializing` functions can be used to initialize parent contracts.
           *
           * Similar to `reinitializer(1)`, except that functions marked with `initializer` can be nested in the context of a
           * constructor.
           *
           * Emits an {Initialized} event.
           */
          modifier initializer() {
              bool isTopLevelCall = !_initializing;
              require(
                  (isTopLevelCall && _initialized < 1) || (!AddressUpgradeable.isContract(address(this)) && _initialized == 1),
                  "Initializable: contract is already initialized"
              );
              _initialized = 1;
              if (isTopLevelCall) {
                  _initializing = true;
              }
              _;
              if (isTopLevelCall) {
                  _initializing = false;
                  emit Initialized(1);
              }
          }
          /**
           * @dev A modifier that defines a protected reinitializer function that can be invoked at most once, and only if the
           * contract hasn't been initialized to a greater version before. In its scope, `onlyInitializing` functions can be
           * used to initialize parent contracts.
           *
           * A reinitializer may be used after the original initialization step. This is essential to configure modules that
           * are added through upgrades and that require initialization.
           *
           * When `version` is 1, this modifier is similar to `initializer`, except that functions marked with `reinitializer`
           * cannot be nested. If one is invoked in the context of another, execution will revert.
           *
           * Note that versions can jump in increments greater than 1; this implies that if multiple reinitializers coexist in
           * a contract, executing them in the right order is up to the developer or operator.
           *
           * WARNING: setting the version to 255 will prevent any future reinitialization.
           *
           * Emits an {Initialized} event.
           */
          modifier reinitializer(uint8 version) {
              require(!_initializing && _initialized < version, "Initializable: contract is already initialized");
              _initialized = version;
              _initializing = true;
              _;
              _initializing = false;
              emit Initialized(version);
          }
          /**
           * @dev Modifier to protect an initialization function so that it can only be invoked by functions with the
           * {initializer} and {reinitializer} modifiers, directly or indirectly.
           */
          modifier onlyInitializing() {
              require(_initializing, "Initializable: contract is not initializing");
              _;
          }
          /**
           * @dev Locks the contract, preventing any future reinitialization. This cannot be part of an initializer call.
           * Calling this in the constructor of a contract will prevent that contract from being initialized or reinitialized
           * to any version. It is recommended to use this to lock implementation contracts that are designed to be called
           * through proxies.
           *
           * Emits an {Initialized} event the first time it is successfully executed.
           */
          function _disableInitializers() internal virtual {
              require(!_initializing, "Initializable: contract is initializing");
              if (_initialized != type(uint8).max) {
                  _initialized = type(uint8).max;
                  emit Initialized(type(uint8).max);
              }
          }
          /**
           * @dev Returns the highest version that has been initialized. See {reinitializer}.
           */
          function _getInitializedVersion() internal view returns (uint8) {
              return _initialized;
          }
          /**
           * @dev Returns `true` if the contract is currently initializing. See {onlyInitializing}.
           */
          function _isInitializing() internal view returns (bool) {
              return _initializing;
          }
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/ERC20.sol)
      pragma solidity ^0.8.0;
      import "./IERC20Upgradeable.sol";
      import "./extensions/IERC20MetadataUpgradeable.sol";
      import "../../utils/ContextUpgradeable.sol";
      import "../../proxy/utils/Initializable.sol";
      /**
       * @dev Implementation of the {IERC20} interface.
       *
       * This implementation is agnostic to the way tokens are created. This means
       * that a supply mechanism has to be added in a derived contract using {_mint}.
       * For a generic mechanism see {ERC20PresetMinterPauser}.
       *
       * TIP: For a detailed writeup see our guide
       * https://forum.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
       * to implement supply mechanisms].
       *
       * The default value of {decimals} is 18. To change this, you should override
       * this function so it returns a different value.
       *
       * We have followed general OpenZeppelin Contracts guidelines: functions revert
       * instead returning `false` on failure. This behavior is nonetheless
       * conventional and does not conflict with the expectations of ERC20
       * applications.
       *
       * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
       * This allows applications to reconstruct the allowance for all accounts just
       * by listening to said events. Other implementations of the EIP may not emit
       * these events, as it isn't required by the specification.
       *
       * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
       * functions have been added to mitigate the well-known issues around setting
       * allowances. See {IERC20-approve}.
       */
      contract ERC20Upgradeable is Initializable, ContextUpgradeable, IERC20Upgradeable, IERC20MetadataUpgradeable {
          mapping(address => uint256) private _balances;
          mapping(address => mapping(address => uint256)) private _allowances;
          uint256 private _totalSupply;
          string private _name;
          string private _symbol;
          /**
           * @dev Sets the values for {name} and {symbol}.
           *
           * All two of these values are immutable: they can only be set once during
           * construction.
           */
          function __ERC20_init(string memory name_, string memory symbol_) internal onlyInitializing {
              __ERC20_init_unchained(name_, symbol_);
          }
          function __ERC20_init_unchained(string memory name_, string memory symbol_) internal onlyInitializing {
              _name = name_;
              _symbol = symbol_;
          }
          /**
           * @dev Returns the name of the token.
           */
          function name() public view virtual override returns (string memory) {
              return _name;
          }
          /**
           * @dev Returns the symbol of the token, usually a shorter version of the
           * name.
           */
          function symbol() public view virtual override returns (string memory) {
              return _symbol;
          }
          /**
           * @dev Returns the number of decimals used to get its user representation.
           * For example, if `decimals` equals `2`, a balance of `505` tokens should
           * be displayed to a user as `5.05` (`505 / 10 ** 2`).
           *
           * Tokens usually opt for a value of 18, imitating the relationship between
           * Ether and Wei. This is the default value returned by this function, unless
           * it's overridden.
           *
           * NOTE: This information is only used for _display_ purposes: it in
           * no way affects any of the arithmetic of the contract, including
           * {IERC20-balanceOf} and {IERC20-transfer}.
           */
          function decimals() public view virtual override returns (uint8) {
              return 18;
          }
          /**
           * @dev See {IERC20-totalSupply}.
           */
          function totalSupply() public view virtual override returns (uint256) {
              return _totalSupply;
          }
          /**
           * @dev See {IERC20-balanceOf}.
           */
          function balanceOf(address account) public view virtual override returns (uint256) {
              return _balances[account];
          }
          /**
           * @dev See {IERC20-transfer}.
           *
           * Requirements:
           *
           * - `to` cannot be the zero address.
           * - the caller must have a balance of at least `amount`.
           */
          function transfer(address to, uint256 amount) public virtual override returns (bool) {
              address owner = _msgSender();
              _transfer(owner, to, amount);
              return true;
          }
          /**
           * @dev See {IERC20-allowance}.
           */
          function allowance(address owner, address spender) public view virtual override returns (uint256) {
              return _allowances[owner][spender];
          }
          /**
           * @dev See {IERC20-approve}.
           *
           * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
           * `transferFrom`. This is semantically equivalent to an infinite approval.
           *
           * Requirements:
           *
           * - `spender` cannot be the zero address.
           */
          function approve(address spender, uint256 amount) public virtual override returns (bool) {
              address owner = _msgSender();
              _approve(owner, spender, amount);
              return true;
          }
          /**
           * @dev See {IERC20-transferFrom}.
           *
           * Emits an {Approval} event indicating the updated allowance. This is not
           * required by the EIP. See the note at the beginning of {ERC20}.
           *
           * NOTE: Does not update the allowance if the current allowance
           * is the maximum `uint256`.
           *
           * Requirements:
           *
           * - `from` and `to` cannot be the zero address.
           * - `from` must have a balance of at least `amount`.
           * - the caller must have allowance for ``from``'s tokens of at least
           * `amount`.
           */
          function transferFrom(address from, address to, uint256 amount) public virtual override returns (bool) {
              address spender = _msgSender();
              _spendAllowance(from, spender, amount);
              _transfer(from, to, amount);
              return true;
          }
          /**
           * @dev Atomically increases the allowance granted to `spender` by the caller.
           *
           * This is an alternative to {approve} that can be used as a mitigation for
           * problems described in {IERC20-approve}.
           *
           * Emits an {Approval} event indicating the updated allowance.
           *
           * Requirements:
           *
           * - `spender` cannot be the zero address.
           */
          function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
              address owner = _msgSender();
              _approve(owner, spender, allowance(owner, spender) + addedValue);
              return true;
          }
          /**
           * @dev Atomically decreases the allowance granted to `spender` by the caller.
           *
           * This is an alternative to {approve} that can be used as a mitigation for
           * problems described in {IERC20-approve}.
           *
           * Emits an {Approval} event indicating the updated allowance.
           *
           * Requirements:
           *
           * - `spender` cannot be the zero address.
           * - `spender` must have allowance for the caller of at least
           * `subtractedValue`.
           */
          function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
              address owner = _msgSender();
              uint256 currentAllowance = allowance(owner, spender);
              require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
              unchecked {
                  _approve(owner, spender, currentAllowance - subtractedValue);
              }
              return true;
          }
          /**
           * @dev Moves `amount` of tokens from `from` to `to`.
           *
           * This internal function is equivalent to {transfer}, and can be used to
           * e.g. implement automatic token fees, slashing mechanisms, etc.
           *
           * Emits a {Transfer} event.
           *
           * Requirements:
           *
           * - `from` cannot be the zero address.
           * - `to` cannot be the zero address.
           * - `from` must have a balance of at least `amount`.
           */
          function _transfer(address from, address to, uint256 amount) internal virtual {
              require(from != address(0), "ERC20: transfer from the zero address");
              require(to != address(0), "ERC20: transfer to the zero address");
              _beforeTokenTransfer(from, to, amount);
              uint256 fromBalance = _balances[from];
              require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
              unchecked {
                  _balances[from] = fromBalance - amount;
                  // Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
                  // decrementing then incrementing.
                  _balances[to] += amount;
              }
              emit Transfer(from, to, amount);
              _afterTokenTransfer(from, to, amount);
          }
          /** @dev Creates `amount` tokens and assigns them to `account`, increasing
           * the total supply.
           *
           * Emits a {Transfer} event with `from` set to the zero address.
           *
           * Requirements:
           *
           * - `account` cannot be the zero address.
           */
          function _mint(address account, uint256 amount) internal virtual {
              require(account != address(0), "ERC20: mint to the zero address");
              _beforeTokenTransfer(address(0), account, amount);
              _totalSupply += amount;
              unchecked {
                  // Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
                  _balances[account] += amount;
              }
              emit Transfer(address(0), account, amount);
              _afterTokenTransfer(address(0), account, amount);
          }
          /**
           * @dev Destroys `amount` tokens from `account`, reducing the
           * total supply.
           *
           * Emits a {Transfer} event with `to` set to the zero address.
           *
           * Requirements:
           *
           * - `account` cannot be the zero address.
           * - `account` must have at least `amount` tokens.
           */
          function _burn(address account, uint256 amount) internal virtual {
              require(account != address(0), "ERC20: burn from the zero address");
              _beforeTokenTransfer(account, address(0), amount);
              uint256 accountBalance = _balances[account];
              require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
              unchecked {
                  _balances[account] = accountBalance - amount;
                  // Overflow not possible: amount <= accountBalance <= totalSupply.
                  _totalSupply -= amount;
              }
              emit Transfer(account, address(0), amount);
              _afterTokenTransfer(account, address(0), amount);
          }
          /**
           * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
           *
           * This internal function is equivalent to `approve`, and can be used to
           * e.g. set automatic allowances for certain subsystems, etc.
           *
           * Emits an {Approval} event.
           *
           * Requirements:
           *
           * - `owner` cannot be the zero address.
           * - `spender` cannot be the zero address.
           */
          function _approve(address owner, address spender, uint256 amount) internal virtual {
              require(owner != address(0), "ERC20: approve from the zero address");
              require(spender != address(0), "ERC20: approve to the zero address");
              _allowances[owner][spender] = amount;
              emit Approval(owner, spender, amount);
          }
          /**
           * @dev Updates `owner` s allowance for `spender` based on spent `amount`.
           *
           * Does not update the allowance amount in case of infinite allowance.
           * Revert if not enough allowance is available.
           *
           * Might emit an {Approval} event.
           */
          function _spendAllowance(address owner, address spender, uint256 amount) internal virtual {
              uint256 currentAllowance = allowance(owner, spender);
              if (currentAllowance != type(uint256).max) {
                  require(currentAllowance >= amount, "ERC20: insufficient allowance");
                  unchecked {
                      _approve(owner, spender, currentAllowance - amount);
                  }
              }
          }
          /**
           * @dev Hook that is called before any transfer of tokens. This includes
           * minting and burning.
           *
           * Calling conditions:
           *
           * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
           * will be transferred to `to`.
           * - when `from` is zero, `amount` tokens will be minted for `to`.
           * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
           * - `from` and `to` are never both zero.
           *
           * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
           */
          function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual {}
          /**
           * @dev Hook that is called after any transfer of tokens. This includes
           * minting and burning.
           *
           * Calling conditions:
           *
           * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
           * has been transferred to `to`.
           * - when `from` is zero, `amount` tokens have been minted for `to`.
           * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
           * - `from` and `to` are never both zero.
           *
           * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
           */
          function _afterTokenTransfer(address from, address to, uint256 amount) internal virtual {}
          /**
           * @dev This empty reserved space is put in place to allow future versions to add new
           * variables without shifting down storage in the inheritance chain.
           * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
           */
          uint256[45] private __gap;
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)
      pragma solidity ^0.8.0;
      import "../IERC20Upgradeable.sol";
      /**
       * @dev Interface for the optional metadata functions from the ERC20 standard.
       *
       * _Available since v4.1._
       */
      interface IERC20MetadataUpgradeable is IERC20Upgradeable {
          /**
           * @dev Returns the name of the token.
           */
          function name() external view returns (string memory);
          /**
           * @dev Returns the symbol of the token.
           */
          function symbol() external view returns (string memory);
          /**
           * @dev Returns the decimals places of the token.
           */
          function decimals() external view returns (uint8);
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)
      pragma solidity ^0.8.0;
      /**
       * @dev Interface of the ERC20 standard as defined in the EIP.
       */
      interface IERC20Upgradeable {
          /**
           * @dev Emitted when `value` tokens are moved from one account (`from`) to
           * another (`to`).
           *
           * Note that `value` may be zero.
           */
          event Transfer(address indexed from, address indexed to, uint256 value);
          /**
           * @dev Emitted when the allowance of a `spender` for an `owner` is set by
           * a call to {approve}. `value` is the new allowance.
           */
          event Approval(address indexed owner, address indexed spender, uint256 value);
          /**
           * @dev Returns the amount of tokens in existence.
           */
          function totalSupply() external view returns (uint256);
          /**
           * @dev Returns the amount of tokens owned by `account`.
           */
          function balanceOf(address account) external view returns (uint256);
          /**
           * @dev Moves `amount` tokens from the caller's account to `to`.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * Emits a {Transfer} event.
           */
          function transfer(address to, uint256 amount) external returns (bool);
          /**
           * @dev Returns the remaining number of tokens that `spender` will be
           * allowed to spend on behalf of `owner` through {transferFrom}. This is
           * zero by default.
           *
           * This value changes when {approve} or {transferFrom} are called.
           */
          function allowance(address owner, address spender) external view returns (uint256);
          /**
           * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * IMPORTANT: Beware that changing an allowance with this method brings the risk
           * that someone may use both the old and the new allowance by unfortunate
           * transaction ordering. One possible solution to mitigate this race
           * condition is to first reduce the spender's allowance to 0 and set the
           * desired value afterwards:
           * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
           *
           * Emits an {Approval} event.
           */
          function approve(address spender, uint256 amount) external returns (bool);
          /**
           * @dev Moves `amount` tokens from `from` to `to` using the
           * allowance mechanism. `amount` is then deducted from the caller's
           * allowance.
           *
           * Returns a boolean value indicating whether the operation succeeded.
           *
           * Emits a {Transfer} event.
           */
          function transferFrom(address from, address to, uint256 amount) external returns (bool);
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts (last updated v4.9.0) (utils/Address.sol)
      pragma solidity ^0.8.1;
      /**
       * @dev Collection of functions related to the address type
       */
      library AddressUpgradeable {
          /**
           * @dev Returns true if `account` is a contract.
           *
           * [IMPORTANT]
           * ====
           * It is unsafe to assume that an address for which this function returns
           * false is an externally-owned account (EOA) and not a contract.
           *
           * Among others, `isContract` will return false for the following
           * types of addresses:
           *
           *  - an externally-owned account
           *  - a contract in construction
           *  - an address where a contract will be created
           *  - an address where a contract lived, but was destroyed
           *
           * Furthermore, `isContract` will also return true if the target contract within
           * the same transaction is already scheduled for destruction by `SELFDESTRUCT`,
           * which only has an effect at the end of a transaction.
           * ====
           *
           * [IMPORTANT]
           * ====
           * You shouldn't rely on `isContract` to protect against flash loan attacks!
           *
           * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
           * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
           * constructor.
           * ====
           */
          function isContract(address account) internal view returns (bool) {
              // This method relies on extcodesize/address.code.length, which returns 0
              // for contracts in construction, since the code is only stored at the end
              // of the constructor execution.
              return account.code.length > 0;
          }
          /**
           * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
           * `recipient`, forwarding all available gas and reverting on errors.
           *
           * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
           * of certain opcodes, possibly making contracts go over the 2300 gas limit
           * imposed by `transfer`, making them unable to receive funds via
           * `transfer`. {sendValue} removes this limitation.
           *
           * https://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/[Learn more].
           *
           * IMPORTANT: because control is transferred to `recipient`, care must be
           * taken to not create reentrancy vulnerabilities. Consider using
           * {ReentrancyGuard} or the
           * https://solidity.readthedocs.io/en/v0.8.0/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
           */
          function sendValue(address payable recipient, uint256 amount) internal {
              require(address(this).balance >= amount, "Address: insufficient balance");
              (bool success, ) = recipient.call{value: amount}("");
              require(success, "Address: unable to send value, recipient may have reverted");
          }
          /**
           * @dev Performs a Solidity function call using a low level `call`. A
           * plain `call` is an unsafe replacement for a function call: use this
           * function instead.
           *
           * If `target` reverts with a revert reason, it is bubbled up by this
           * function (like regular Solidity function calls).
           *
           * Returns the raw returned data. To convert to the expected return value,
           * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
           *
           * Requirements:
           *
           * - `target` must be a contract.
           * - calling `target` with `data` must not revert.
           *
           * _Available since v3.1._
           */
          function functionCall(address target, bytes memory data) internal returns (bytes memory) {
              return functionCallWithValue(target, data, 0, "Address: low-level call failed");
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
           * `errorMessage` as a fallback revert reason when `target` reverts.
           *
           * _Available since v3.1._
           */
          function functionCall(
              address target,
              bytes memory data,
              string memory errorMessage
          ) internal returns (bytes memory) {
              return functionCallWithValue(target, data, 0, errorMessage);
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
           * but also transferring `value` wei to `target`.
           *
           * Requirements:
           *
           * - the calling contract must have an ETH balance of at least `value`.
           * - the called Solidity function must be `payable`.
           *
           * _Available since v3.1._
           */
          function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
              return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
          }
          /**
           * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
           * with `errorMessage` as a fallback revert reason when `target` reverts.
           *
           * _Available since v3.1._
           */
          function functionCallWithValue(
              address target,
              bytes memory data,
              uint256 value,
              string memory errorMessage
          ) internal returns (bytes memory) {
              require(address(this).balance >= value, "Address: insufficient balance for call");
              (bool success, bytes memory returndata) = target.call{value: value}(data);
              return verifyCallResultFromTarget(target, success, returndata, errorMessage);
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
           * but performing a static call.
           *
           * _Available since v3.3._
           */
          function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
              return functionStaticCall(target, data, "Address: low-level static call failed");
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
           * but performing a static call.
           *
           * _Available since v3.3._
           */
          function functionStaticCall(
              address target,
              bytes memory data,
              string memory errorMessage
          ) internal view returns (bytes memory) {
              (bool success, bytes memory returndata) = target.staticcall(data);
              return verifyCallResultFromTarget(target, success, returndata, errorMessage);
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
           * but performing a delegate call.
           *
           * _Available since v3.4._
           */
          function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
              return functionDelegateCall(target, data, "Address: low-level delegate call failed");
          }
          /**
           * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
           * but performing a delegate call.
           *
           * _Available since v3.4._
           */
          function functionDelegateCall(
              address target,
              bytes memory data,
              string memory errorMessage
          ) internal returns (bytes memory) {
              (bool success, bytes memory returndata) = target.delegatecall(data);
              return verifyCallResultFromTarget(target, success, returndata, errorMessage);
          }
          /**
           * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
           * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
           *
           * _Available since v4.8._
           */
          function verifyCallResultFromTarget(
              address target,
              bool success,
              bytes memory returndata,
              string memory errorMessage
          ) internal view returns (bytes memory) {
              if (success) {
                  if (returndata.length == 0) {
                      // only check isContract if the call was successful and the return data is empty
                      // otherwise we already know that it was a contract
                      require(isContract(target), "Address: call to non-contract");
                  }
                  return returndata;
              } else {
                  _revert(returndata, errorMessage);
              }
          }
          /**
           * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
           * revert reason or using the provided one.
           *
           * _Available since v4.3._
           */
          function verifyCallResult(
              bool success,
              bytes memory returndata,
              string memory errorMessage
          ) internal pure returns (bytes memory) {
              if (success) {
                  return returndata;
              } else {
                  _revert(returndata, errorMessage);
              }
          }
          function _revert(bytes memory returndata, string memory errorMessage) private pure {
              // Look for revert reason and bubble it up if present
              if (returndata.length > 0) {
                  // The easiest way to bubble the revert reason is using memory via assembly
                  /// @solidity memory-safe-assembly
                  assembly {
                      let returndata_size := mload(returndata)
                      revert(add(32, returndata), returndata_size)
                  }
              } else {
                  revert(errorMessage);
              }
          }
      }
      // SPDX-License-Identifier: MIT
      // OpenZeppelin Contracts v4.4.1 (utils/Context.sol)
      pragma solidity ^0.8.0;
      import "../proxy/utils/Initializable.sol";
      /**
       * @dev Provides information about the current execution context, including the
       * sender of the transaction and its data. While these are generally available
       * via msg.sender and msg.data, they should not be accessed in such a direct
       * manner, since when dealing with meta-transactions the account sending and
       * paying for execution may not be the actual sender (as far as an application
       * is concerned).
       *
       * This contract is only required for intermediate, library-like contracts.
       */
      abstract contract ContextUpgradeable is Initializable {
          function __Context_init() internal onlyInitializing {
          }
          function __Context_init_unchained() internal onlyInitializing {
          }
          function _msgSender() internal view virtual returns (address) {
              return msg.sender;
          }
          function _msgData() internal view virtual returns (bytes calldata) {
              return msg.data;
          }
          /**
           * @dev This empty reserved space is put in place to allow future versions to add new
           * variables without shifting down storage in the inheritance chain.
           * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
           */
          uint256[50] private __gap;
      }
      // SPDX-License-Identifier: BUSL-1.1
      pragma solidity 0.8.19;
      /// @dev Error for 0x0 address inputs
      error InvalidZeroInput();    
      /// @dev Error for already added items to a list
      error AlreadyAdded();    
      /// @dev Error for not found items in a list
      error NotFound();    
      /// @dev Error for hitting max TVL
      error MaxTVLReached();
      /// @dev Error for caller not having permissions
      error NotRestakeManagerAdmin();
      /// @dev Error for call not coming from deposit queue contract
      error NotDepositQueue();
      /// @dev Error for contract being paused
      error ContractPaused(); 
      /// @dev Error for exceeding max basis points (100%)
      error OverMaxBasisPoints();
      /// @dev Error for invalid token decimals for collateral tokens (must be 18)
      error InvalidTokenDecimals(uint8 expected, uint8 actual);
      /// @dev Error when withdraw is already completed
      error WithdrawAlreadyCompleted();
      /// @dev Error when a different address tries to complete withdraw
      error NotOriginalWithdrawCaller(address expectedCaller);
      /// @dev Error when caller does not have OD admin role
      error NotOperatorDelegatorAdmin();
      /// @dev Error when caller does not have Oracle Admin role
      error NotOracleAdmin();
      /// @dev Error when caller is not RestakeManager contract
      error NotRestakeManager();
      /// @dev Errror when caller does not have ETH Restake Admin role
      error NotNativeEthRestakeAdmin();
      /// @dev Error when delegation address was already set - cannot be set again
      error DelegateAddressAlreadySet();
      /// @dev Error when caller does not have ERC20 Rewards Admin role
      error NotERC20RewardsAdmin();
      /// @dev Error when ending ETH fails
      error TransferFailed();
      /// @dev Error when caller does not have ETH Minter Burner Admin role
      error NotEzETHMinterBurner();
      /// @dev Error when caller does not have Token Admin role
      error NotTokenAdmin();
      /// @dev Error when price oracle is not configured
      error OracleNotFound();
      /// @dev Error when price oracle data is stale
      error OraclePriceExpired();
      /// @dev Error when array lengths do not match
      error MismatchedArrayLengths();
      /// @dev Error when caller does not have Deposit Withdraw Pauser role
      error NotDepositWithdrawPauser();//SPDX-License-Identifier: MIT
      pragma solidity 0.8.19;
      interface IRoleManager {
          /// @dev Determines if the specified address has permissions to manage RoleManager
          /// @param potentialAddress Address to check
          function isRoleManagerAdmin(address potentialAddress) external view returns (bool);
          /// @dev Determines if the specified address has permission to mint or burn ezETH tokens
          /// @param potentialAddress Address to check
          function isEzETHMinterBurner(address potentialAddress)
              external
              view
              returns (bool);
          /// @dev Determines if the specified address has permission to update config on the OperatorDelgator Contracts
          /// @param potentialAddress Address to check
          function isOperatorDelegatorAdmin(address potentialAddress)
              external
              view
              returns (bool);
          /// @dev Determines if the specified address has permission to update config on the Oracle Contract config
          /// @param potentialAddress Address to check
          function isOracleAdmin(address potentialAddress)
              external
              view
              returns (bool);
          /// @dev Determines if the specified address has permission to update config on the Restake Manager
          /// @param potentialAddress Address to check
          function isRestakeManagerAdmin(address potentialAddress)
              external
              view
              returns (bool);
          /// @dev Determines if the specified address has permission to update config on the Token Contract
          /// @param potentialAddress Address to check
          function isTokenAdmin(address potentialAddress)
              external
              view
              returns (bool);
          
          /// @dev Determines if the specified address has permission to trigger restaking of native ETH
          /// @param potentialAddress Address to check
          function isNativeEthRestakeAdmin(address potentialAddress)
              external
              view
              returns (bool);        
          /// @dev Determines if the specified address has permission to sweep and deposit ERC20 Rewards
          /// @param potentialAddress Address to check
          function isERC20RewardsAdmin(address potentialAddress)
              external
              view
              returns (bool);        
          
          /// @dev Determines if the specified address has permission to pause deposits and withdraws
          /// @param potentialAddress Address to check
          function isDepositWithdrawPauser(address potentialAddress)
              external
              view
              returns (bool);
      }
      // SPDX-License-Identifier: BUSL-1.1
      pragma solidity ^0.8.9;
      import "@openzeppelin/contracts-upgradeable/token/ERC20/ERC20Upgradeable.sol";
      import "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
      import "./IEzEthToken.sol";
      import "../Permissions/IRoleManager.sol";
      import "./EzEthTokenStorage.sol";
      import "../Errors/Errors.sol";
      /// @dev This contract is the ezETH ERC20 token
      /// Ownership of the collateral in the protocol is tracked by the ezETH token
      contract EzEthToken is    
          Initializable,
          ERC20Upgradeable,
          IEzEthToken, 
          EzEthTokenStorageV1
      {
          /// @dev Allows only a whitelisted address to mint or burn ezETH tokens
          modifier onlyMinterBurner() {
              if(!roleManager.isEzETHMinterBurner(msg.sender)) revert NotEzETHMinterBurner();
              _;
          }
          /// @dev Allows only a whitelisted address to pause or unpause the token
          modifier onlyTokenAdmin() {
              if(!roleManager.isTokenAdmin(msg.sender)) revert NotTokenAdmin();
              _;
          }
          /// @dev Prevents implementation contract from being initialized.
          /// @custom:oz-upgrades-unsafe-allow constructor
          constructor() {
              _disableInitializers();
          }
          /// @dev Initializes the contract with initial vars
          function initialize(IRoleManager _roleManager) public initializer {
              if(address(_roleManager) == address(0x0)) revert InvalidZeroInput();
              __ERC20_init("ezETH", "Renzo Restaked ETH");
              roleManager = _roleManager;
          }
          /// @dev Allows minter/burner to mint new ezETH tokens to an address
          function mint(address to, uint256 amount) external onlyMinterBurner {
              _mint(to, amount);
          }
          /// @dev Allows minter/burner to burn ezETH tokens from an address
          function burn(address from, uint256 amount) external onlyMinterBurner {
              _burn(from, amount);
          }
          /// @dev Sets the paused flag
          function setPaused(bool _paused) external onlyTokenAdmin {
              paused = _paused;
          }
          /// @dev 
          function _beforeTokenTransfer(address from, address to, uint256 amount)
              internal virtual override
          {
              super._beforeTokenTransfer(from, to, amount);
              // If not paused return success
              if (!paused) {
                  return;
              }
              // If paused, only minting and burning should be allowed
              if (from != address(0) && to != address(0)) {
                  revert ContractPaused();
              }
          }
          /**
           * @dev Returns the name of the token.
           */
          function name() public view virtual override returns (string memory) {
              return "Renzo Restaked ETH";
          }
          /**
           * @dev Returns the symbol of the token, usually a shorter version of the
           * name.
           */
          function symbol() public view virtual override returns (string memory) {
              return "ezETH";
          }
      }
      //SPDX-License-Identifier: MIT
      pragma solidity 0.8.19;
      import "../Permissions/IRoleManager.sol";
      /// @title EzEthTokenStorage
      /// @dev This contract will hold all local variables for the  Contract
      /// When upgrading the protocol, inherit from this contract on the V2 version and change the
      /// StorageManager to inherit from the later version.  This ensures there are no storage layout
      /// corruptions when upgrading.
      contract EzEthTokenStorageV1 {
          /// @dev reference to the RoleManager contract
          IRoleManager public roleManager;
          /// @dev flag to control whether transfers are paused
          bool public paused;
      }
      /// On the next version of the protocol, if new variables are added, put them in the below
      /// contract and use this as the inheritance chain.
      /**
      contract EzEthTokenStorageV2 is EzEthTokenStorageV1 {
        address newVariable;
      }
       */
      // SPDX-License-Identifier: BUSL-1.1
      pragma solidity ^0.8.9;
      import "@openzeppelin/contracts-upgradeable/token/ERC20/IERC20Upgradeable.sol";
      interface IEzEthToken is IERC20Upgradeable {
          function mint(address to, uint256 amount) external;
          function burn(address from, uint256 amount) external;
      }