ETH Price: $2,300.21 (+5.28%)

Transaction Decoder

Block:
22256866 at Apr-13-2025 01:49:23 AM +UTC
Transaction Fee:
0.000028403076251615 ETH $0.07
Gas Used:
54,535 Gas / 0.520822889 Gwei

Emitted Events:

388 0xfa103c21ea2df71dfb92b0652f8b1d795e51cdef.0xef4b96e5b208365900f38219a7dec7af4565f8ff4ce6526970a9d024397f978d( 0xef4b96e5b208365900f38219a7dec7af4565f8ff4ce6526970a9d024397f978d, 000000000000000000000000def1ca1fb7fbcdc777520aa7f396b4e015f497ab, 000000000000000000000000a69babef1ca67a37ffaf7a485dfff3382056e78c, 0000000000000000000000001bf7a9e3a364e7f5761345837f222cd93e230c4f, 000000000000000000000000000000000000000000003e8f7458bdef3ac30000 )
389 CowProtocolToken.Transfer( from=0xA69babEF1cA67A37Ffaf7a485DfFF3382056e78C, to=0x1BF7A9E3A364e7F5761345837f222cd93e230C4f, value=295432990000000000000000 )
390 CowProtocolToken.Approval( owner=0xA69babEF1cA67A37Ffaf7a485DfFF3382056e78C, spender=[Receiver] 0xfa103c21ea2df71dfb92b0652f8b1d795e51cdef, value=115792089237316195423570985008687907853269984665640554887028494007913129639935 )

Account State Difference:

  Address   Before After State Difference Code
(beaverbuild)
5.766188806057043956 Eth5.766189430077435301 Eth0.000000624020391345
0xDEf1CA1f...015F497aB
0xf06443E7...d10f4adeE
8.045783862838676939 Eth
Nonce: 23004
8.045755459762425324 Eth
Nonce: 23005
0.000028403076251615

Execution Trace

0xfa103c21ea2df71dfb92b0652f8b1d795e51cdef.1cff79cd( )
  • 0xa456fc5d92990bb6a5710bdc738c6ef3001dfb6f.52de3cbd( )
    • CowProtocolToken.transferFrom( sender=0xA69babEF1cA67A37Ffaf7a485DfFF3382056e78C, recipient=0x1BF7A9E3A364e7F5761345837f222cd93e230C4f, amount=295432990000000000000000 ) => ( True )
      // SPDX-License-Identifier: LGPL-3.0-or-later
      pragma solidity ^0.8.10;
      import "./mixins/InflationaryToken.sol";
      import "./vendored/mixins/StorageAccessible.sol";
      /// @dev The governance token for the CoW Protocol.
      /// @title CoW Protocol Governance Token
      /// @author CoW Protocol Developers
      contract CowProtocolToken is InflationaryToken, StorageAccessible {
          string private constant ERC20_SYMBOL = "COW";
          string private constant ERC20_NAME = "CoW Protocol Token";
          constructor(
              address initialTokenHolder,
              address cowDao,
              uint256 totalSupply
          )
              InflationaryToken(
                  initialTokenHolder,
                  cowDao,
                  totalSupply,
                  ERC20_NAME,
                  ERC20_SYMBOL
              )
          // solhint-disable-next-line no-empty-blocks
          {
          }
      }
      // SPDX-License-Identifier: LGPL-3.0-or-later
      pragma solidity ^0.8.10;
      import "../vendored/mixins/ERC20.sol";
      import "../vendored/mixins/draft-ERC20Permit.sol";
      /// @dev Contract contains the logic for minting new tokens
      /// @title Mintable Token
      /// @author CoW Protocol Developers
      contract InflationaryToken is ERC20, ERC20Permit {
          /// @dev Defines the cowDao address that is allowed to mint new tokens
          address public immutable cowDao;
          /// @dev Defines how frequently inflation can be triggered: Once a year
          uint256 public constant TIME_BETWEEN_MINTINGS = 365 days;
          /// @dev Defines the maximal inflation per year
          uint256 public constant MAX_YEARLY_INFLATION = 3;
          /// @dev Stores the timestamp of the last inflation event
          uint256 public timestampLastMinting = 0;
          /// @dev Error caused by an attempt to mint too many tokens.
          error ExceedingMintCap();
          /// @dev Error caused by calling the mint function more than once within one year.
          error AlreadyInflated();
          /// @dev Error caused by calling the mint function from a non-cowDao account.
          error OnlyCowDao();
          modifier onlyCowDao() {
              if (msg.sender != cowDao) {
                  revert OnlyCowDao();
              }
              _;
          }
          constructor(
              address initialTokenHolder,
              address _cowDao,
              uint256 totalSupply,
              string memory erc20Name,
              string memory erc20Symbol
          ) ERC20(erc20Name, erc20Symbol) ERC20Permit(erc20Name) {
              _mint(initialTokenHolder, totalSupply);
              cowDao = _cowDao;
              // solhint-disable-next-line not-rely-on-time
              timestampLastMinting = block.timestamp;
          }
          /// @dev This function allows to mint new tokens
          /// @param target The address that should receive the new tokens
          /// @param amount The amount of tokens to be minted.
          function mint(address target, uint256 amount) external onlyCowDao {
              if (amount > (totalSupply() * MAX_YEARLY_INFLATION) / 100) {
                  revert ExceedingMintCap();
              }
              // solhint-disable-next-line not-rely-on-time
              if (timestampLastMinting + TIME_BETWEEN_MINTINGS > block.timestamp) {
                  revert AlreadyInflated();
              }
              timestampLastMinting = block.timestamp; // solhint-disable-line not-rely-on-time
              _mint(target, amount);
          }
      }
      // SPDX-License-Identifier: LGPL-3.0-only
      // Vendored from Gnosis utility contracts, see:
      // <https://raw.githubusercontent.com/gnosis/gp-v2-contracts/40c349d52d14f8f3c9f787fe2fca5a496bb10ea9/src/contracts/mixins/StorageAccessible.sol>
      // The following changes were made:
      // - Modified Solidity version
      // - Formatted code
      pragma solidity ^0.8.10;
      /// @title ViewStorageAccessible - Interface on top of StorageAccessible base class to allow simulations from view functions
      interface ViewStorageAccessible {
          /**
           * @dev Same as `simulateDelegatecall` on StorageAccessible. Marked as view so that it can be called from external contracts
           * that want to run simulations from within view functions. Will revert if the invoked simulation attempts to change state.
           */
          function simulateDelegatecall(
              address targetContract,
              bytes memory calldataPayload
          ) external view returns (bytes memory);
          /**
           * @dev Same as `getStorageAt` on StorageAccessible. This method allows reading aribtrary ranges of storage.
           */
          function getStorageAt(uint256 offset, uint256 length)
              external
              view
              returns (bytes memory);
      }
      /// @title StorageAccessible - generic base contract that allows callers to access all internal storage.
      contract StorageAccessible {
          /**
           * @dev Reads `length` bytes of storage in the currents contract
           * @param offset - the offset in the current contract's storage in words to start reading from
           * @param length - the number of words (32 bytes) of data to read
           * @return the bytes that were read.
           */
          function getStorageAt(uint256 offset, uint256 length)
              external
              view
              returns (bytes memory)
          {
              bytes memory result = new bytes(length * 32);
              for (uint256 index = 0; index < length; index++) {
                  // solhint-disable-next-line no-inline-assembly
                  assembly {
                      let word := sload(add(offset, index))
                      mstore(add(add(result, 0x20), mul(index, 0x20)), word)
                  }
              }
              return result;
          }
          /**
           * @dev Performs a delegetecall on a targetContract in the context of self.
           * Internally reverts execution to avoid side effects (making it static). Catches revert and returns encoded result as bytes.
           * @param targetContract Address of the contract containing the code to execute.
           * @param calldataPayload Calldata that should be sent to the target contract (encoded method name and arguments).
           */
          function simulateDelegatecall(
              address targetContract,
              bytes memory calldataPayload
          ) public returns (bytes memory response) {
              bytes memory innerCall = abi.encodeWithSelector(
                  this.simulateDelegatecallInternal.selector,
                  targetContract,
                  calldataPayload
              );
              // solhint-disable-next-line avoid-low-level-calls
              (, response) = address(this).call(innerCall);
              bool innerSuccess = response[response.length - 1] == 0x01;
              setLength(response, response.length - 1);
              if (innerSuccess) {
                  return response;
              } else {
                  revertWith(response);
              }
          }
          /**
           * @dev Performs a delegetecall on a targetContract in the context of self.
           * Internally reverts execution to avoid side effects (making it static). Returns encoded result as revert message
           * concatenated with the success flag of the inner call as a last byte.
           * @param targetContract Address of the contract containing the code to execute.
           * @param calldataPayload Calldata that should be sent to the target contract (encoded method name and arguments).
           */
          function simulateDelegatecallInternal(
              address targetContract,
              bytes memory calldataPayload
          ) external returns (bytes memory response) {
              bool success;
              // solhint-disable-next-line avoid-low-level-calls
              (success, response) = targetContract.delegatecall(calldataPayload);
              revertWith(abi.encodePacked(response, success));
          }
          function revertWith(bytes memory response) internal pure {
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  revert(add(response, 0x20), mload(response))
              }
          }
          function setLength(bytes memory buffer, uint256 length) internal pure {
              // solhint-disable-next-line no-inline-assembly
              assembly {
                  mstore(buffer, length)
              }
          }
      }
      // SPDX-License-Identifier: MIT
      // Vendored from OpenZeppelin Contracts v4.4.0, see:
      // <https://raw.githubusercontent.com/OpenZeppelin/openzeppelin-contracts/v4.4.0/contracts/token/ERC20/ERC20.sol>
      // The following changes were made:
      // - Vendored imports
      // OpenZeppelin Contracts v4.4.0 (token/ERC20/ERC20.sol)
      pragma solidity ^0.8.0;
      import "../interfaces/IERC20.sol";
      import "../interfaces/IERC20Metadata.sol";
      import "../interfaces/Context.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 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 ERC20 is Context, IERC20, IERC20Metadata {
          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}.
           *
           * The default value of {decimals} is 18. To select a different value for
           * {decimals} you should overload it.
           *
           * All two of these values are immutable: they can only be set once during
           * construction.
           */
          constructor(string memory name_, string memory symbol_) {
              _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 value {ERC20} uses, unless this function is
           * 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:
           *
           * - `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(_msgSender(), 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(_msgSender(), 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);
              uint256 currentAllowance = _allowances[sender][_msgSender()];
              require(
                  currentAllowance >= amount,
                  "ERC20: transfer amount exceeds allowance"
              );
              unchecked {
                  _approve(sender, _msgSender(), currentAllowance - 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)
          {
              _approve(
                  _msgSender(),
                  spender,
                  _allowances[_msgSender()][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)
          {
              uint256 currentAllowance = _allowances[_msgSender()][spender];
              require(
                  currentAllowance >= subtractedValue,
                  "ERC20: decreased allowance below zero"
              );
              unchecked {
                  _approve(_msgSender(), spender, currentAllowance - subtractedValue);
              }
              return true;
          }
          /**
           * @dev Moves `amount` of tokens from `sender` to `recipient`.
           *
           * 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:
           *
           * - `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), "ERC20: transfer from the zero address");
              require(recipient != address(0), "ERC20: transfer to the zero address");
              _beforeTokenTransfer(sender, recipient, amount);
              uint256 senderBalance = _balances[sender];
              require(
                  senderBalance >= amount,
                  "ERC20: transfer amount exceeds balance"
              );
              unchecked {
                  _balances[sender] = senderBalance - amount;
              }
              _balances[recipient] += amount;
              emit Transfer(sender, recipient, amount);
              _afterTokenTransfer(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:
           *
           * - `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;
              _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;
              }
              _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 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 {}
      }
      // SPDX-License-Identifier: MIT
      // Vendored from OpenZeppelin Contracts v4.4.0, see:
      // <https://raw.githubusercontent.com/OpenZeppelin/openzeppelin-contracts/v4.4.0/contracts/token/ERC20/extensions/draft-ERC20Permit.sol>
      // The following changes were made:
      // - Vendored imports
      // OpenZeppelin Contracts v4.4.0 (token/ERC20/extensions/draft-ERC20Permit.sol)
      pragma solidity ^0.8.0;
      import "../interfaces/draft-IERC20Permit.sol";
      import "./ERC20.sol";
      import "./draft-EIP712.sol";
      import "../libraries/ECDSA.sol";
      import "../libraries/Counters.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, EIP712 {
          using Counters for Counters.Counter;
          mapping(address => Counters.Counter) private _nonces;
          // solhint-disable-next-line var-name-mixedcase
          bytes32 private immutable _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") {}
          /**
           * @dev See {IERC20Permit-permit}.
           */
          function permit(
              address owner,
              address spender,
              uint256 value,
              uint256 deadline,
              uint8 v,
              bytes32 r,
              bytes32 s
          ) public virtual override {
              require(block.timestamp <= deadline, "ERC20Permit: expired deadline");
              bytes32 structHash = keccak256(
                  abi.encode(
                      _PERMIT_TYPEHASH,
                      owner,
                      spender,
                      value,
                      _useNonce(owner),
                      deadline
                  )
              );
              bytes32 hash = _hashTypedDataV4(structHash);
              address signer = ECDSA.recover(hash, v, r, s);
              require(signer == owner, "ERC20Permit: invalid signature");
              _approve(owner, spender, value);
          }
          /**
           * @dev See {IERC20Permit-nonces}.
           */
          function nonces(address owner)
              public
              view
              virtual
              override
              returns (uint256)
          {
              return _nonces[owner].current();
          }
          /**
           * @dev See {IERC20Permit-DOMAIN_SEPARATOR}.
           */
          // solhint-disable-next-line func-name-mixedcase
          function DOMAIN_SEPARATOR() external view override returns (bytes32) {
              return _domainSeparatorV4();
          }
          /**
           * @dev "Consume a nonce": return the current value and increment.
           *
           * _Available since v4.1._
           */
          function _useNonce(address owner)
              internal
              virtual
              returns (uint256 current)
          {
              Counters.Counter storage nonce = _nonces[owner];
              current = nonce.current();
              nonce.increment();
          }
      }
      // SPDX-License-Identifier: MIT
      // Vendored from OpenZeppelin Contracts v4.4.0, see:
      // <https://raw.githubusercontent.com/OpenZeppelin/openzeppelin-contracts/v4.4.0/contracts/token/ERC20/IERC20.sol>
      // OpenZeppelin Contracts v4.4.0 (token/ERC20/IERC20.sol)
      pragma solidity ^0.8.0;
      /**
       * @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: MIT
      // Vendored from OpenZeppelin Contracts v4.4.0, see:
      // <https://raw.githubusercontent.com/OpenZeppelin/openzeppelin-contracts/v4.4.0/contracts/token/ERC20/extensions/IERC20Metadata.sol>
      // The following changes were made:
      // - Vendored imports
      // OpenZeppelin Contracts v4.4.0 (token/ERC20/extensions/IERC20Metadata.sol)
      pragma solidity ^0.8.0;
      import "./IERC20.sol";
      /**
       * @dev Interface for the optional metadata functions from the ERC20 standard.
       *
       * _Available since v4.1._
       */
      interface IERC20Metadata is IERC20 {
          /**
           * @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
      // Vendored from OpenZeppelin Contracts v4.4.0, see:
      // <https://raw.githubusercontent.com/OpenZeppelin/openzeppelin-contracts/v4.4.0/contracts/utils/Context.sol>
      // OpenZeppelin Contracts v4.4.0 (utils/Context.sol)
      pragma solidity ^0.8.0;
      /**
       * @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 Context {
          function _msgSender() internal view virtual returns (address) {
              return msg.sender;
          }
          function _msgData() internal view virtual returns (bytes calldata) {
              return msg.data;
          }
      }
      // SPDX-License-Identifier: MIT
      // Vendored from OpenZeppelin Contracts v4.4.0, see:
      // <https://raw.githubusercontent.com/OpenZeppelin/openzeppelin-contracts/v4.4.0/contracts/token/ERC20/extensions/draft-IERC20Permit.sol>
      // OpenZeppelin Contracts v4.4.0 (token/ERC20/extensions/draft-IERC20Permit.sol)
      pragma solidity ^0.8.0;
      /**
       * @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: MIT
      // Vendored from OpenZeppelin Contracts v4.4.0, see:
      // <https://raw.githubusercontent.com/OpenZeppelin/openzeppelin-contracts/v4.4.0/contracts/utils/cryptography/draft-EIP712.sol>
      // The following changes were made:
      // - Vendored imports
      // OpenZeppelin Contracts v4.4.0 (utils/cryptography/draft-EIP712.sol)
      pragma solidity ^0.8.0;
      import "../libraries/ECDSA.sol";
      /**
       * @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 */
          // Cache the domain separator as an immutable value, but also store the chain id that it corresponds to, in order to
          // invalidate the cached domain separator if the chain id changes.
          bytes32 private immutable _CACHED_DOMAIN_SEPARATOR;
          uint256 private immutable _CACHED_CHAIN_ID;
          address private immutable _CACHED_THIS;
          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) {
              bytes32 hashedName = keccak256(bytes(name));
              bytes32 hashedVersion = keccak256(bytes(version));
              bytes32 typeHash = keccak256(
                  "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
              );
              _HASHED_NAME = hashedName;
              _HASHED_VERSION = hashedVersion;
              _CACHED_CHAIN_ID = block.chainid;
              _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator(
                  typeHash,
                  hashedName,
                  hashedVersion
              );
              _CACHED_THIS = address(this);
              _TYPE_HASH = typeHash;
          }
          /**
           * @dev Returns the domain separator for the current chain.
           */
          function _domainSeparatorV4() internal view returns (bytes32) {
              if (
                  address(this) == _CACHED_THIS && block.chainid == _CACHED_CHAIN_ID
              ) {
                  return _CACHED_DOMAIN_SEPARATOR;
              } else {
                  return
                      _buildDomainSeparator(
                          _TYPE_HASH,
                          _HASHED_NAME,
                          _HASHED_VERSION
                      );
              }
          }
          function _buildDomainSeparator(
              bytes32 typeHash,
              bytes32 nameHash,
              bytes32 versionHash
          ) private view returns (bytes32) {
              return
                  keccak256(
                      abi.encode(
                          typeHash,
                          nameHash,
                          versionHash,
                          block.chainid,
                          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 ECDSA.toTypedDataHash(_domainSeparatorV4(), structHash);
          }
      }
      // SPDX-License-Identifier: MIT
      // Vendored from OpenZeppelin Contracts v4.4.0, see:
      // <https://raw.githubusercontent.com/OpenZeppelin/openzeppelin-contracts/v4.4.0/contracts/utils/cryptography/ECDSA.sol>
      // The following changes were made:
      // - Vendored imports
      // OpenZeppelin Contracts v4.4.0 (utils/cryptography/ECDSA.sol)
      pragma solidity ^0.8.0;
      import "./Strings.sol";
      /**
       * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
       *
       * These functions can be used to verify that a message was signed by the holder
       * of the private keys of a given address.
       */
      library ECDSA {
          enum RecoverError {
              NoError,
              InvalidSignature,
              InvalidSignatureLength,
              InvalidSignatureS,
              InvalidSignatureV
          }
          function _throwError(RecoverError error) private pure {
              if (error == RecoverError.NoError) {
                  return; // no error: do nothing
              } else if (error == RecoverError.InvalidSignature) {
                  revert("ECDSA: invalid signature");
              } else if (error == RecoverError.InvalidSignatureLength) {
                  revert("ECDSA: invalid signature length");
              } else if (error == RecoverError.InvalidSignatureS) {
                  revert("ECDSA: invalid signature 's' value");
              } else if (error == RecoverError.InvalidSignatureV) {
                  revert("ECDSA: invalid signature 'v' value");
              }
          }
          /**
           * @dev Returns the address that signed a hashed message (`hash`) with
           * `signature` or error string. This address can then be used for verification purposes.
           *
           * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
           * this function rejects them by requiring the `s` value to be in the lower
           * half order, and the `v` value to be either 27 or 28.
           *
           * IMPORTANT: `hash` _must_ be the result of a hash operation for the
           * verification to be secure: it is possible to craft signatures that
           * recover to arbitrary addresses for non-hashed data. A safe way to ensure
           * this is by receiving a hash of the original message (which may otherwise
           * be too long), and then calling {toEthSignedMessageHash} on it.
           *
           * Documentation for signature generation:
           * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
           * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
           *
           * _Available since v4.3._
           */
          function tryRecover(bytes32 hash, bytes memory signature)
              internal
              pure
              returns (address, RecoverError)
          {
              // Check the signature length
              // - case 65: r,s,v signature (standard)
              // - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
              if (signature.length == 65) {
                  bytes32 r;
                  bytes32 s;
                  uint8 v;
                  // ecrecover takes the signature parameters, and the only way to get them
                  // currently is to use assembly.
                  assembly {
                      r := mload(add(signature, 0x20))
                      s := mload(add(signature, 0x40))
                      v := byte(0, mload(add(signature, 0x60)))
                  }
                  return tryRecover(hash, v, r, s);
              } else if (signature.length == 64) {
                  bytes32 r;
                  bytes32 vs;
                  // ecrecover takes the signature parameters, and the only way to get them
                  // currently is to use assembly.
                  assembly {
                      r := mload(add(signature, 0x20))
                      vs := mload(add(signature, 0x40))
                  }
                  return tryRecover(hash, r, vs);
              } else {
                  return (address(0), RecoverError.InvalidSignatureLength);
              }
          }
          /**
           * @dev Returns the address that signed a hashed message (`hash`) with
           * `signature`. This address can then be used for verification purposes.
           *
           * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
           * this function rejects them by requiring the `s` value to be in the lower
           * half order, and the `v` value to be either 27 or 28.
           *
           * IMPORTANT: `hash` _must_ be the result of a hash operation for the
           * verification to be secure: it is possible to craft signatures that
           * recover to arbitrary addresses for non-hashed data. A safe way to ensure
           * this is by receiving a hash of the original message (which may otherwise
           * be too long), and then calling {toEthSignedMessageHash} on it.
           */
          function recover(bytes32 hash, bytes memory signature)
              internal
              pure
              returns (address)
          {
              (address recovered, RecoverError error) = tryRecover(hash, signature);
              _throwError(error);
              return recovered;
          }
          /**
           * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
           *
           * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
           *
           * _Available since v4.3._
           */
          function tryRecover(
              bytes32 hash,
              bytes32 r,
              bytes32 vs
          ) internal pure returns (address, RecoverError) {
              bytes32 s;
              uint8 v;
              assembly {
                  s := and(
                      vs,
                      0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
                  )
                  v := add(shr(255, vs), 27)
              }
              return tryRecover(hash, v, r, s);
          }
          /**
           * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
           *
           * _Available since v4.2._
           */
          function recover(
              bytes32 hash,
              bytes32 r,
              bytes32 vs
          ) internal pure returns (address) {
              (address recovered, RecoverError error) = tryRecover(hash, r, vs);
              _throwError(error);
              return recovered;
          }
          /**
           * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
           * `r` and `s` signature fields separately.
           *
           * _Available since v4.3._
           */
          function tryRecover(
              bytes32 hash,
              uint8 v,
              bytes32 r,
              bytes32 s
          ) internal pure returns (address, RecoverError) {
              // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
              // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
              // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
              // signatures from current libraries generate a unique signature with an s-value in the lower half order.
              //
              // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
              // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
              // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
              // these malleable signatures as well.
              if (
                  uint256(s) >
                  0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0
              ) {
                  return (address(0), RecoverError.InvalidSignatureS);
              }
              if (v != 27 && v != 28) {
                  return (address(0), RecoverError.InvalidSignatureV);
              }
              // If the signature is valid (and not malleable), return the signer address
              address signer = ecrecover(hash, v, r, s);
              if (signer == address(0)) {
                  return (address(0), RecoverError.InvalidSignature);
              }
              return (signer, RecoverError.NoError);
          }
          /**
           * @dev Overload of {ECDSA-recover} that receives the `v`,
           * `r` and `s` signature fields separately.
           */
          function recover(
              bytes32 hash,
              uint8 v,
              bytes32 r,
              bytes32 s
          ) internal pure returns (address) {
              (address recovered, RecoverError error) = tryRecover(hash, v, r, s);
              _throwError(error);
              return recovered;
          }
          /**
           * @dev Returns an Ethereum Signed Message, created from a `hash`. This
           * produces hash corresponding to the one signed with the
           * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
           * JSON-RPC method as part of EIP-191.
           *
           * See {recover}.
           */
          function toEthSignedMessageHash(bytes32 hash)
              internal
              pure
              returns (bytes32)
          {
              // 32 is the length in bytes of hash,
              // enforced by the type signature above
              return
                  keccak256(
                      abi.encodePacked("\\x19Ethereum Signed Message:\
      32", hash)
                  );
          }
          /**
           * @dev Returns an Ethereum Signed Message, created from `s`. This
           * produces hash corresponding to the one signed with the
           * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
           * JSON-RPC method as part of EIP-191.
           *
           * See {recover}.
           */
          function toEthSignedMessageHash(bytes memory s)
              internal
              pure
              returns (bytes32)
          {
              return
                  keccak256(
                      abi.encodePacked(
                          "\\x19Ethereum Signed Message:\
      ",
                          Strings.toString(s.length),
                          s
                      )
                  );
          }
          /**
           * @dev Returns an Ethereum Signed Typed Data, created from a
           * `domainSeparator` and a `structHash`. This produces hash corresponding
           * to the one signed with the
           * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
           * JSON-RPC method as part of EIP-712.
           *
           * See {recover}.
           */
          function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash)
              internal
              pure
              returns (bytes32)
          {
              return
                  keccak256(
                      abi.encodePacked("\\x19\\x01", domainSeparator, structHash)
                  );
          }
      }
      // SPDX-License-Identifier: MIT
      // Vendored from OpenZeppelin Contracts v4.4.0, see:
      // <https://raw.githubusercontent.com/OpenZeppelin/openzeppelin-contracts/v4.4.0/contracts/utils/Counters.sol>
      // OpenZeppelin Contracts v4.4.0 (utils/Counters.sol)
      pragma solidity ^0.8.0;
      /**
       * @title Counters
       * @author Matt Condon (@shrugs)
       * @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
       * of elements in a mapping, issuing ERC721 ids, or counting request ids.
       *
       * Include with `using Counters for Counters.Counter;`
       */
      library Counters {
          struct Counter {
              // This variable should never be directly accessed by users of the library: interactions must be restricted to
              // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
              // this feature: see https://github.com/ethereum/solidity/issues/4637
              uint256 _value; // default: 0
          }
          function current(Counter storage counter) internal view returns (uint256) {
              return counter._value;
          }
          function increment(Counter storage counter) internal {
              unchecked {
                  counter._value += 1;
              }
          }
          function decrement(Counter storage counter) internal {
              uint256 value = counter._value;
              require(value > 0, "Counter: decrement overflow");
              unchecked {
                  counter._value = value - 1;
              }
          }
          function reset(Counter storage counter) internal {
              counter._value = 0;
          }
      }
      // SPDX-License-Identifier: MIT
      // Vendored from OpenZeppelin Contracts v4.4.0, see:
      // <https://raw.githubusercontent.com/OpenZeppelin/openzeppelin-contracts/v4.4.0/contracts/utils/Strings.sol>
      // OpenZeppelin Contracts v4.4.0 (utils/Strings.sol)
      pragma solidity ^0.8.0;
      /**
       * @dev String operations.
       */
      library Strings {
          bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
          /**
           * @dev Converts a `uint256` to its ASCII `string` decimal representation.
           */
          function toString(uint256 value) internal pure returns (string memory) {
              // Inspired by OraclizeAPI's implementation - MIT licence
              // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol
              if (value == 0) {
                  return "0";
              }
              uint256 temp = value;
              uint256 digits;
              while (temp != 0) {
                  digits++;
                  temp /= 10;
              }
              bytes memory buffer = new bytes(digits);
              while (value != 0) {
                  digits -= 1;
                  buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
                  value /= 10;
              }
              return string(buffer);
          }
          /**
           * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
           */
          function toHexString(uint256 value) internal pure returns (string memory) {
              if (value == 0) {
                  return "0x00";
              }
              uint256 temp = value;
              uint256 length = 0;
              while (temp != 0) {
                  length++;
                  temp >>= 8;
              }
              return toHexString(value, length);
          }
          /**
           * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
           */
          function toHexString(uint256 value, uint256 length)
              internal
              pure
              returns (string memory)
          {
              bytes memory buffer = new bytes(2 * length + 2);
              buffer[0] = "0";
              buffer[1] = "x";
              for (uint256 i = 2 * length + 1; i > 1; --i) {
                  buffer[i] = _HEX_SYMBOLS[value & 0xf];
                  value >>= 4;
              }
              require(value == 0, "Strings: hex length insufficient");
              return string(buffer);
          }
      }