Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity 0.8.6;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";
interface IERC677 is IERC20, IERC20Metadata {
function transferAndCall(address recipient, uint amount, bytes memory data) external returns (bool success);
event Transfer(address indexed from, address indexed to, uint value, bytes data);
}
interface IERC677Receiver {
function onTokenTransfer(address sender, uint value, bytes memory data) external;
}
// SPDX-License-Identifier: MIT
pragma solidity 0.8.6;
pragma experimental ABIEncoderV2;
import "./IERC677.sol";
interface IyVaren {
// Event emitted when a new proposal is created
event ProposalCreated(
uint256 id,
address indexed proposer,
address[] targets,
uint256[] values,
string[] signatures,
bytes[] calldatas,
uint256 startBlock,
uint256 endBlock,
string description
);
// Event emitted when a vote has been cast on a proposal
event VoteCast(
address indexed voter,
uint256 proposalId,
bool support,
uint256 votes
);
// Event emitted when a proposal has been executed
// Success=true if all actions were executed successfully
// Success=false if not all actions were executed successfully (executeProposal will not revert)
event ProposalExecuted(uint256 id, bool success);
// Maximum number of actions that can be included in a proposal
function MAX_OPERATIONS() external pure returns (uint256);
// https://etherscan.io/token/0x72377f31e30a405282b522d588aebbea202b4f23
function VAREN() external returns (IERC677);
struct Proposal {
// Address that created the proposal
address proposer;
// Number of votes in support of the proposal by a particular address
mapping(address => uint256) forVotes;
// Number of votes against the proposal by a particular address
mapping(address => uint256) againstVotes;
// Total number of votes in support of the proposal
uint256 totalForVotes;
// Total number of votes against the proposal
uint256 totalAgainstVotes;
// Number of votes in support of a proposal required for a quorum to be reached and for a vote to succeed
uint256 quorumVotes;
// Block at which voting ends: votes must be cast prior to this block
uint256 endBlock;
// Ordered list of target addresses for calls to be made on
address[] targets;
// Ordered list of ETH values (i.e. msg.value) to be passed to the calls to be made
uint256[] values;
// Ordered list of function signatures to be called
string[] signatures;
// Ordered list of calldata to be passed to each call
bytes[] calldatas;
// Flag marking whether the proposal has been executed
bool executed;
}
// Number of blocks after staking when the early withdrawal fee stops applying
function blocksForNoWithdrawalFee() external view returns (uint256);
// Fee for withdrawing before blocksForNoWithdrawalFee have passed, divide by 1,000,000 to get decimal form
function earlyWithdrawalFeePercent() external view returns (uint256);
function earlyWithdrawalFeeExpiry(address) external view returns (uint256);
function treasury() external view returns (address);
// Share of early withdrawal fee that goes to treasury (remainder goes to governance),
// divide by 1,000,000 to get decimal form
function treasuryEarlyWithdrawalFeeShare() external view returns (uint256);
// Amount of an address's stake that is locked for voting
function voteLockAmount(address) external view returns (uint256);
// Block number when an address's vote-locked amount will be unlock
function voteLockExpiry(address) external view returns (uint256);
function hasActiveProposal(address) external view returns (bool);
function proposals(uint256 id)
external
view
returns (
address proposer,
uint256 totalForVotes,
uint256 totalAgainstVotes,
uint256 quorumVotes,
uint256 endBlock,
bool executed
);
// Number of proposals created, used as the id for the next proposal
function proposalCount() external view returns (uint256);
// Length of voting period in blocks
function votingPeriodBlocks() external view returns (uint256);
function minVarenForProposal() external view returns (uint256);
// Need to divide by 1,000,000
function quorumPercent() external view returns (uint256);
// Need to divide by 1,000,000
function voteThresholdPercent() external view returns (uint256);
// Number of blocks after voting ends where proposals are allowed to be executed
function executionPeriodBlocks() external view returns (uint256);
function stake(uint256 amount) external;
function withdraw(uint256 shares) external;
function getPricePerFullShare() external view returns (uint256);
function getStakeVarenValue(address staker) external view returns (uint256);
function propose(
address[] calldata targets,
uint256[] calldata values,
string[] calldata signatures,
bytes[] calldata calldatas,
string calldata description
) external returns (uint256 id);
function vote(
uint256 id,
bool support,
uint256 voteAmount
) external;
function executeProposal(uint256 id) external payable;
function getVotes(uint256 proposalId, address voter)
external
view
returns (bool support, uint256 voteAmount);
function getProposalCalls(uint256 proposalId)
external
view
returns (
address[] memory targets,
uint256[] memory values,
string[] memory signatures,
bytes[] memory calldatas
);
function setTreasury(address) external;
function setTreasuryEarlyWithdrawalFeeShare(uint256) external;
function setBlocksForNoWithdrawalFee(uint256) external;
function setEarlyWithdrawalFeePercent(uint256) external;
function setVotingPeriodBlocks(uint256) external;
function setMinVarenForProposal(uint256) external;
function setQuorumPercent(uint256) external;
function setVoteThresholdPercent(uint256) external;
function setExecutionPeriodBlocks(uint256) external;
}
// SPDX-License-Identifier: MIT
pragma solidity 0.8.6;
pragma experimental ABIEncoderV2;
import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "./interfaces/IyVaren.sol";
import "./interfaces/IERC677.sol";
contract yVaren is IyVaren, IERC677Receiver, ERC20, ReentrancyGuard {
using SafeERC20 for IERC20;
using Address for address;
using SafeMath for uint256;
uint256 public constant override MAX_OPERATIONS = 10;
IERC677 public immutable override VAREN;
uint256 public override blocksForNoWithdrawalFee;
uint256 public override earlyWithdrawalFeePercent = 5000; // 0.5%
mapping(address => uint256) public override earlyWithdrawalFeeExpiry;
address public override treasury;
uint256 public override treasuryEarlyWithdrawalFeeShare = 1000000; // 100%
mapping(address => uint256) public override voteLockAmount;
mapping(address => uint256) public override voteLockExpiry;
mapping(address => bool) public override hasActiveProposal;
mapping(uint256 => Proposal) public override proposals;
uint256 public override proposalCount;
uint256 public override votingPeriodBlocks;
uint256 public override minVarenForProposal = 1e17; // 0.1 Varen
uint256 public override quorumPercent = 150000; // 15%
uint256 public override voteThresholdPercent = 500000; // 50%
uint256 public override executionPeriodBlocks;
modifier onlyThis() {
require(msg.sender == address(this), "yVRN: FORBIDDEN");
_;
}
constructor(
address _varen,
address _treasury,
uint256 _blocksForNoWithdrawalFee,
uint256 _votingPeriodBlocks,
uint256 _executionPeriodBlocks
) ERC20("Varen Staking Share", "yVRN") {
require(
_varen != address(0) && _treasury != address(0),
"yVRN: ZERO_ADDRESS"
);
VAREN = IERC677(_varen);
treasury = _treasury;
blocksForNoWithdrawalFee = _blocksForNoWithdrawalFee;
votingPeriodBlocks = _votingPeriodBlocks;
executionPeriodBlocks = _executionPeriodBlocks;
}
function stake(uint256 amount) external override nonReentrant {
require(amount > 0, "yVRN: ZERO");
require(VAREN.transferFrom(msg.sender, address(this), amount), 'yVRN: transferFrom failed');
_stake(msg.sender, amount);
}
function _stake(address sender, uint256 amount) internal virtual {
uint256 shares = totalSupply() == 0
? amount
: (amount.mul(totalSupply())).div(VAREN.balanceOf(address(this)).sub(amount));
_mint(sender, shares);
earlyWithdrawalFeeExpiry[sender] = blocksForNoWithdrawalFee.add(
block.number
);
}
function onTokenTransfer(address sender, uint value, bytes memory) external override nonReentrant {
require(value > 0, "yVRN: ZERO");
require(msg.sender == address(VAREN), 'yVRN: access denied');
_stake(sender, value);
}
function withdraw(uint256 shares) external override nonReentrant {
require(shares > 0, "yVRN: ZERO");
_updateVoteExpiry();
require(_checkVoteExpiry(msg.sender, shares), "voteLockExpiry");
uint256 varenAmount = (VAREN.balanceOf(address(this))).mul(shares).div(
totalSupply()
);
_burn(msg.sender, shares);
if (block.number < earlyWithdrawalFeeExpiry[msg.sender]) {
uint256 feeAmount = varenAmount.mul(earlyWithdrawalFeePercent) /
1000000;
VAREN.transfer(
treasury,
feeAmount.mul(treasuryEarlyWithdrawalFeeShare) / 1000000
);
varenAmount = varenAmount.sub(feeAmount);
}
VAREN.transfer(msg.sender, varenAmount);
}
function getPricePerFullShare() external view override returns (uint256) {
return totalSupply() == 0 ? 0 : VAREN.balanceOf(address(this)).mul(1e18).div(totalSupply());
}
function getStakeVarenValue(address staker)
external
view
override
returns (uint256)
{
return
(VAREN.balanceOf(address(this)).mul(balanceOf(staker))).div(
totalSupply()
);
}
function propose(
address[] memory targets,
uint256[] memory values,
string[] memory signatures,
bytes[] memory calldatas,
string memory description
) public override nonReentrant returns (uint256 id) {
require(!hasActiveProposal[msg.sender], "yVRN: HAS_ACTIVE_PROPOSAL");
require(
targets.length == values.length &&
targets.length == signatures.length &&
targets.length == calldatas.length,
"yVRN: PARITY_MISMATCH"
);
require(targets.length != 0, "yVRN: NO_ACTIONS");
require(targets.length <= MAX_OPERATIONS, "yVRN: TOO_MANY_ACTIONS");
require(
(VAREN.balanceOf(address(this)).mul(balanceOf(msg.sender))).div(
totalSupply()
) >= minVarenForProposal,
"yVRN: INSUFFICIENT_VAREN_FOR_PROPOSAL"
);
uint256 endBlock = votingPeriodBlocks.add(block.number);
Proposal storage newProposal = proposals[proposalCount];
newProposal.proposer = msg.sender;
newProposal.endBlock = endBlock;
newProposal.targets = targets;
newProposal.values = values;
newProposal.signatures = signatures;
newProposal.calldatas = calldatas;
newProposal.totalForVotes = 0;
newProposal.totalAgainstVotes = 0;
newProposal.quorumVotes = VAREN.balanceOf(address(this)).mul(quorumPercent) / 1000000;
newProposal.executed = false;
hasActiveProposal[msg.sender] = true;
proposalCount = proposalCount.add(1);
emit ProposalCreated(
id,
msg.sender,
targets,
values,
signatures,
calldatas,
block.number,
endBlock,
description
);
}
function _checkVoteExpiry(address _sender, uint256 _shares)
private
view
returns (bool)
{
// ?????
return _shares <= balanceOf(_sender).sub(voteLockAmount[_sender]);
}
function _updateVoteExpiry() private {
if (block.number >= voteLockExpiry[msg.sender]) {
voteLockExpiry[msg.sender] = 0;
voteLockAmount[msg.sender] = 0;
}
}
function vote(
uint256 id,
bool support,
uint256 voteAmount
) external override nonReentrant {
Proposal storage proposal = proposals[id];
require(proposal.proposer != address(0), "yVRN: INVALID_PROPOSAL_ID");
require(block.number < proposal.endBlock, "yVRN: VOTING_ENDED");
require(voteAmount > 0, "yVRN: ZERO");
require(
voteAmount <= balanceOf(msg.sender),
"yVRN: INSUFFICIENT_BALANCE"
);
_updateVoteExpiry();
require(
voteAmount >= voteLockAmount[msg.sender],
"yVRN: SMALLER_VOTE"
);
if (
(support && voteAmount == proposal.forVotes[msg.sender]) ||
(!support && voteAmount == proposal.againstVotes[msg.sender])
) {
revert("yVRN: SAME_VOTE");
}
if (voteAmount > voteLockAmount[msg.sender]) {
voteLockAmount[msg.sender] = voteAmount;
}
voteLockExpiry[msg.sender] = proposal.endBlock >
voteLockExpiry[msg.sender]
? proposal.endBlock
: voteLockExpiry[msg.sender];
if (support) {
proposal.totalForVotes = proposal.totalForVotes.add(voteAmount).sub(
proposal.forVotes[msg.sender]
);
proposal.forVotes[msg.sender] = voteAmount;
// remove opposite votes
proposal.totalAgainstVotes = proposal.totalAgainstVotes.sub(
proposal.againstVotes[msg.sender]
);
proposal.againstVotes[msg.sender] = 0;
} else {
proposal.totalAgainstVotes = proposal
.totalAgainstVotes
.add(voteAmount)
.sub(proposal.againstVotes[msg.sender]);
proposal.againstVotes[msg.sender] = voteAmount;
// remove opposite votes
proposal.totalForVotes = proposal.totalForVotes.sub(
proposal.forVotes[msg.sender]
);
proposal.forVotes[msg.sender] = 0;
}
emit VoteCast(msg.sender, id, support, voteAmount);
}
function executeProposal(uint256 id)
external
payable
override
nonReentrant
{
Proposal storage proposal = proposals[id];
require(!proposal.executed, "yVRN: PROPOSAL_ALREADY_EXECUTED");
{
// check if proposal passed
require(
proposal.proposer != address(0),
"yVRN: INVALID_PROPOSAL_ID"
);
require(
block.number >= proposal.endBlock,
"yVRN: PROPOSAL_IN_VOTING"
);
hasActiveProposal[proposal.proposer] = false;
uint256 totalVotes = proposal.totalForVotes.add(
proposal.totalAgainstVotes
);
if (
totalVotes < proposal.quorumVotes ||
proposal.totalForVotes <
totalVotes.mul(voteThresholdPercent) / 1000000 ||
block.number >= proposal.endBlock.add(executionPeriodBlocks) // execution period ended
) {
return;
}
}
bool success = true;
uint256 remainingValue = msg.value;
for (uint256 i = 0; i < proposal.targets.length; i++) {
if (proposal.values[i] > 0) {
require(
remainingValue >= proposal.values[i],
"yVRN: INSUFFICIENT_ETH"
);
remainingValue = remainingValue - proposal.values[i];
}
(success, ) = proposal.targets[i].call{value: proposal.values[i]}(
abi.encodePacked(
bytes4(keccak256(bytes(proposal.signatures[i]))),
proposal.calldatas[i]
)
);
if (!success) break;
}
proposal.executed = true;
emit ProposalExecuted(id, success);
}
function getVotes(uint256 proposalId, address voter)
external
view
override
returns (bool support, uint256 voteAmount)
{
support = proposals[proposalId].forVotes[voter] > 0;
voteAmount = support
? proposals[proposalId].forVotes[voter]
: proposals[proposalId].againstVotes[voter];
}
function getProposalCalls(uint256 proposalId)
external
view
override
returns (
address[] memory targets,
uint256[] memory values,
string[] memory signatures,
bytes[] memory calldatas
)
{
targets = proposals[proposalId].targets;
values = proposals[proposalId].values;
signatures = proposals[proposalId].signatures;
calldatas = proposals[proposalId].calldatas;
}
// SETTERS
function setTreasury(address _treasury) external override onlyThis {
treasury = _treasury;
}
function setTreasuryEarlyWithdrawalFeeShare(
uint256 _treasuryEarlyWithdrawalFeeShare
) external override onlyThis {
require(_treasuryEarlyWithdrawalFeeShare <= 1000000);
treasuryEarlyWithdrawalFeeShare = _treasuryEarlyWithdrawalFeeShare;
}
function setBlocksForNoWithdrawalFee(uint256 _blocksForNoWithdrawalFee)
external
override
onlyThis
{
// max 60 days
require(_blocksForNoWithdrawalFee <= 345600);
blocksForNoWithdrawalFee = _blocksForNoWithdrawalFee;
}
function setEarlyWithdrawalFeePercent(uint256 _earlyWithdrawalFeePercent)
external
override
onlyThis
{
// max 100%
require(_earlyWithdrawalFeePercent <= 1000000);
earlyWithdrawalFeePercent = _earlyWithdrawalFeePercent;
}
function setVotingPeriodBlocks(uint256 _votingPeriodBlocks)
external
override
onlyThis
{
// min 8 hours, max 2 weeks
require(_votingPeriodBlocks >= 1920 && _votingPeriodBlocks <= 80640);
votingPeriodBlocks = _votingPeriodBlocks;
}
function setMinVarenForProposal(uint256 _minVarenForProposal)
external
override
onlyThis
{
// min 0.01 Varen, max 520 Varen (1% of total supply)
require(
_minVarenForProposal >= 1e16 && _minVarenForProposal <= 520 * (1e18)
);
minVarenForProposal = _minVarenForProposal;
}
function setQuorumPercent(uint256 _quorumPercent)
external
override
onlyThis
{
// min 10%, max 33%
require(_quorumPercent >= 100000 && _quorumPercent <= 330000);
quorumPercent = _quorumPercent;
}
function setVoteThresholdPercent(uint256 _voteThresholdPercent)
external
override
onlyThis
{
// min 50%, max 66%
require(
_voteThresholdPercent >= 500000 && _voteThresholdPercent <= 660000
);
voteThresholdPercent = _voteThresholdPercent;
}
function setExecutionPeriodBlocks(uint256 _executionPeriodBlocks)
external
override
onlyThis
{
// min 8 hours, max 30 days
require(
_executionPeriodBlocks >= 1920 && _executionPeriodBlocks <= 172800
);
executionPeriodBlocks = _executionPeriodBlocks;
}
// ERC20 functions (overridden to add modifiers)
function transfer(address recipient, uint256 amount)
public
override
nonReentrant
returns (bool)
{
_updateVoteExpiry();
require(_checkVoteExpiry(msg.sender, amount), "voteLockExpiry");
super.transfer(recipient, amount);
}
function approve(address spender, uint256 amount)
public
override
nonReentrant
returns (bool)
{
super.approve(spender, amount);
}
function transferFrom(
address sender,
address recipient,
uint256 amount
) public override nonReentrant returns (bool) {
_updateVoteExpiry();
require(_checkVoteExpiry(sender, amount), "voteLockExpiry");
super.transferFrom(sender, recipient, amount);
}
function increaseAllowance(address spender, uint256 addedValue)
public
override
nonReentrant
returns (bool)
{
super.increaseAllowance(spender, addedValue);
}
function decreaseAllowance(address spender, uint256 subtractedValue)
public
override
nonReentrant
returns (bool)
{
super.decreaseAllowance(spender, subtractedValue);
}
function decimals() public view virtual override returns (uint8) {
return VAREN.decimals();
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @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() {
// On the first call to nonReentrant, _notEntered will be true
require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
// Any calls to nonReentrant after this point will fail
_status = _ENTERED;
_;
// 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
pragma solidity ^0.8.0;
import "./IERC20.sol";
import "./extensions/IERC20Metadata.sol";
import "../../utils/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 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 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
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
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
pragma solidity ^0.8.0;
import "../IERC20.sol";
import "../../../utils/Address.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 {
using Address for address;
function safeTransfer(
IERC20 token,
address to,
uint256 value
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
}
function safeTransferFrom(
IERC20 token,
address from,
address to,
uint256 value
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
}
/**
* @dev Deprecated. This function has issues similar to the ones found in
* {IERC20-approve}, and its usage is discouraged.
*
* Whenever possible, use {safeIncreaseAllowance} and
* {safeDecreaseAllowance} instead.
*/
function safeApprove(
IERC20 token,
address spender,
uint256 value
) internal {
// safeApprove should only be called when setting an initial allowance,
// or when resetting it to zero. To increase and decrease it, use
// 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
require(
(value == 0) || (token.allowance(address(this), spender) == 0),
"SafeERC20: approve from non-zero to non-zero allowance"
);
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
}
function safeIncreaseAllowance(
IERC20 token,
address spender,
uint256 value
) internal {
uint256 newAllowance = token.allowance(address(this), spender) + value;
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
function safeDecreaseAllowance(
IERC20 token,
address spender,
uint256 value
) internal {
unchecked {
uint256 oldAllowance = token.allowance(address(this), spender);
require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
uint256 newAllowance = oldAllowance - value;
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
}
/**
* @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).
* @param token The token targeted by the call.
* @param data The call data (encoded using abi.encode or one of its variants).
*/
function _callOptionalReturn(IERC20 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. We use {Address.functionCall} to perform this call, which verifies that
// the target address contains contract code and also asserts for success in the low-level call.
bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
if (returndata.length > 0) {
// Return data is optional
require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @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;
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, "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);
}
function _verifyCallResult(
bool success,
bytes memory returndata,
string memory errorMessage
) private 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
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
pragma solidity ^0.8.0;
// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.
/**
* @dev Wrappers over Solidity's arithmetic operations.
*
* NOTE: `SafeMath` is no longer needed starting with Solidity 0.8. The compiler
* now has built in overflow checking.
*/
library SafeMath {
/**
* @dev Returns the addition of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
uint256 c = a + b;
if (c < a) return (false, 0);
return (true, c);
}
}
/**
* @dev Returns the substraction of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
if (b > a) return (false, 0);
return (true, a - b);
}
}
/**
* @dev Returns the multiplication of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
if (a == 0) return (true, 0);
uint256 c = a * b;
if (c / a != b) return (false, 0);
return (true, c);
}
}
/**
* @dev Returns the division of two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
if (b == 0) return (false, 0);
return (true, a / b);
}
}
/**
* @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
if (b == 0) return (false, 0);
return (true, a % b);
}
}
/**
* @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) {
return a + b;
}
/**
* @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 a - b;
}
/**
* @dev Returns the multiplication of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `*` operator.
*
* Requirements:
*
* - Multiplication cannot overflow.
*/
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
return a * b;
}
/**
* @dev Returns the integer division of two unsigned integers, reverting on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator.
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return a / b;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return a % b;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {trySub}.
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
*
* - Subtraction cannot overflow.
*/
function sub(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
unchecked {
require(b <= a, errorMessage);
return a - b;
}
}
/**
* @dev Returns the integer division of two unsigned integers, reverting with custom message on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function div(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
unchecked {
require(b > 0, errorMessage);
return a / b;
}
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting with custom message when dividing by zero.
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {tryMod}.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function mod(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
unchecked {
require(b > 0, errorMessage);
return a % b;
}
}
}