Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity 0.8.2;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "./IUniswapV2Factory.sol";
import "./airdropDistributor.sol";
interface IStaking {
function updatePool(uint256 amount) external;
}
contract DigiToads is ERC20, Ownable {
using SafeMath for uint256;
address public treasury;
address public staking;
address public distributorAddress;
bool private swapping;
bool public swapEnable;
bool public distributionEnabled;
uint256 public swapTokensAtAmount;
uint256 public distributorGas;
IERC20 USDT;
uint256[] public liqudityFee;
uint256[] public stakingPoolFee;
uint256[] public treasuryFee;
uint256[] public burnFee;
IUniswapV2Router02 public uniswapV2Router;
address public uniswapV2Pair;
AirDrop distributor;
mapping(address => bool) isDividendExempt;
mapping(address => bool) public whitelistedAddress;
mapping(address => bool) public automatedMarketMakerPairs;
event TreasuryAddressUpdated(address newTreasury);
event StakingAddressUpdated(address newStaking);
event WhitelistAddressUpdated(address whitelistAccount, bool value);
event SetAutomatedMarketMakerPair(address indexed pair, bool indexed value);
event ExcludeFromMaxWalletToken(address indexed account, bool isExcluded);
event SwapTokenAmountUpdated(uint256 indexed amount);
event SwapStatusUpdated(bool indexed status);
constructor(address _owner) ERC20("DigiToads", "$TOADS") {
_mint(_owner, 585000000 * (10**18));
IUniswapV2Router02 _uniswapV2Router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
address _uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory()).createPair(address(this), _uniswapV2Router.WETH());
uniswapV2Router = _uniswapV2Router;
uniswapV2Pair = _uniswapV2Pair;
_setAutomatedMarketMakerPair(_uniswapV2Pair, true);
whitelistedAddress[address(this)] = true;
whitelistedAddress[_owner] = true;
isDividendExempt[_uniswapV2Pair] = true;
isDividendExempt[address(this)] = true;
burnFee.push(200);
burnFee.push(200);
burnFee.push(200);
treasuryFee.push(200);
treasuryFee.push(200);
treasuryFee.push(200);
stakingPoolFee.push(200);
stakingPoolFee.push(200);
stakingPoolFee.push(200);
liqudityFee.push(100);
liqudityFee.push(100);
liqudityFee.push(100);
swapEnable = true;
swapTokensAtAmount = 100000 * (10**18);
distributorGas = 250000;
distributor = new AirDrop();
distributorAddress = address(distributor);
USDT = IERC20(0xdAC17F958D2ee523a2206206994597C13D831ec7);
treasury = address(0x860cEE971686c6b349C13ddde2fDe483aD955418);
}
receive() external payable {}
function setTreasuryAddress(address _treasury) external onlyOwner{
require(_treasury != address(0), "setTreasuryAddress: Zero address");
treasury = _treasury;
whitelistedAddress[_treasury] = true;
emit TreasuryAddressUpdated(_treasury);
}
function setStakingPoolAddress(address _staking) external onlyOwner{
require(_staking != address(0), "setStakingPoolAddress: Zero address");
staking = _staking;
whitelistedAddress[_staking] = true;
emit StakingAddressUpdated(_staking);
}
function setWhitelistAddress(address _whitelist, bool _status) external onlyOwner{
require(_whitelist != address(0), "setWhitelistAddress: Zero address");
whitelistedAddress[_whitelist] = _status;
emit WhitelistAddressUpdated(_whitelist, _status);
}
function setSwapTokensAtAmount(uint256 amount) external onlyOwner {
require(amount <= totalSupply(), "Amount cannot be over the total supply.");
swapTokensAtAmount = amount;
emit SwapTokenAmountUpdated(amount);
}
function setSwapEnable(bool _enabled) public onlyOwner {
swapEnable = _enabled;
emit SwapStatusUpdated(_enabled);
}
function setLiqudityFee(uint256 buy, uint256 sell, uint256 p2p) external onlyOwner {
require(burnFee[0].add(stakingPoolFee[0]).add(treasuryFee[0]).add(buy) <= 2500 , "Max fee limit reached for 'BUY'");
require(burnFee[1].add(stakingPoolFee[1]).add(treasuryFee[0]).add(sell) <= 2500 , "Max fee limit reached for 'SELL'");
require(burnFee[2].add(stakingPoolFee[2]).add(treasuryFee[0]).add(p2p) <= 2500 , "Max fee limit reached for 'P2P'");
liqudityFee[0] = buy;
liqudityFee[1] = sell;
liqudityFee[2] = p2p;
}
function setBurnFee(uint256 buy, uint256 sell, uint256 p2p) external onlyOwner {
require(liqudityFee[0].add(stakingPoolFee[0]).add(treasuryFee[0]).add(buy) <= 2500 , "Max fee limit reached for 'BUY'");
require(liqudityFee[1].add(stakingPoolFee[1]).add(treasuryFee[1]).add(sell) <= 2500 , "Max fee limit reached for 'SELL'");
require(liqudityFee[2].add(stakingPoolFee[2]).add(treasuryFee[2]).add(p2p) <= 2500 , "Max fee limit reached for 'P2P'");
burnFee[0] = buy;
burnFee[1] = sell;
burnFee[2] = p2p;
}
function setStakingPoolFee(uint256 buy, uint256 sell, uint256 p2p) external onlyOwner {
require(liqudityFee[0].add(treasuryFee[0]).add(burnFee[0]).add(buy) <= 2500 , "Max fee limit reached for 'BUY'");
require(liqudityFee[1].add(treasuryFee[1]).add(burnFee[1]).add(sell) <= 2500 , "Max fee limit reached for 'SELL'");
require(liqudityFee[2].add(treasuryFee[2]).add(burnFee[2]).add(p2p) <= 2500 , "Max fee limit reached for 'P2P'");
stakingPoolFee[0] = buy;
stakingPoolFee[1] = sell;
stakingPoolFee[2] = p2p;
}
function setTreasuryFee(uint256 buy, uint256 sell, uint256 p2p) external onlyOwner {
require(liqudityFee[0].add(stakingPoolFee[0]).add(burnFee[0]).add(buy) <= 2500 , "Max fee limit reached for 'BUY'");
require(liqudityFee[1].add(stakingPoolFee[1]).add(burnFee[1]).add(sell) <= 2500 , "Max fee limit reached for 'SELL'");
require(liqudityFee[2].add(stakingPoolFee[2]).add(burnFee[2]).add(p2p) <= 2500 , "Max fee limit reached for 'P2P'");
treasuryFee[0] = buy;
treasuryFee[1] = sell;
treasuryFee[2] = p2p;
}
function setAutomatedMarketMakerPair(address pair, bool value) public onlyOwner {
require(pair != uniswapV2Pair, "The Uniswap pair cannot be removed from automatedMarketMakerPairs");
_setAutomatedMarketMakerPair(pair, value);
}
function _setAutomatedMarketMakerPair(address pair, bool value) private {
require(automatedMarketMakerPairs[pair] != value, "Automated market maker pair is already set to that value");
automatedMarketMakerPairs[pair] = value;
emit SetAutomatedMarketMakerPair(pair, value);
}
function swapTokensForETH(uint256 tokenAmount) private {
address[] memory path = new address[](2);
path[0] = address(this);
path[1] = uniswapV2Router.WETH();
_approve(address(this), address(uniswapV2Router), tokenAmount);
uniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(
tokenAmount,
0,
path,
address(this),
block.timestamp
);
}
function addLiquidity(uint256 tokenAmount, uint256 ETHAmount) private{
_approve(address(this), address(uniswapV2Router), tokenAmount);
uniswapV2Router.addLiquidityETH{value: ETHAmount}(
address(this),
tokenAmount,
0,
0,
address(this),
block.timestamp.add(300)
);
}
function transferTokens(address tokenAddress, address to, uint256 amount) public onlyOwner {
IERC20(tokenAddress).transfer(to, amount);
}
function migrateETH(address payable recipient) public onlyOwner {
require(recipient != address(0), "Zero address");
recipient.transfer(address(this).balance);
}
function _transfer(address sender, address recipient, uint256 amount) internal override(ERC20){
require(sender != address(0), "ERC20: transfer from the zero address");
require(recipient != address(0), "ERC20: transfer to the zero address");
uint256 contractTokenBalance = balanceOf(address(this));
bool canSwap = contractTokenBalance >= swapTokensAtAmount;
if (!swapping && canSwap && swapEnable && automatedMarketMakerPairs[recipient])
{
swapping = true;
uint256 half = swapTokensAtAmount.div(2);
uint256 otherHalf = swapTokensAtAmount.sub(half);
swapTokensForETH(half);
uint256 newBalance = address(this).balance;
if(newBalance > 0) {
addLiquidity(otherHalf, newBalance);
}
swapping = false;
}
if(whitelistedAddress[sender] || whitelistedAddress[recipient])
{
super._transfer(sender, recipient, amount);
}
else
{
(uint256 burnAmount, uint256 treasuryAmount, uint256 stakingAmount, uint256 liqudityAmount) = collectFee(amount, automatedMarketMakerPairs[recipient], !automatedMarketMakerPairs[sender] && !automatedMarketMakerPairs[recipient]);
if(burnAmount > 0)
{
super._burn(sender, burnAmount);
}
if(treasuryAmount > 0)
{
super._transfer(sender, address(treasury), treasuryAmount);
}
if(stakingAmount > 0)
{
super._transfer(sender, address(staking), stakingAmount);
IStaking(staking).updatePool(stakingAmount);
}
if(liqudityAmount > 0)
{
super._transfer(sender, address(this), liqudityAmount);
}
uint256 allFee = burnAmount.add(treasuryAmount).add(stakingAmount).add(liqudityAmount);
super._transfer(sender, recipient, amount.sub(allFee));
}
if(!isDividendExempt[sender]){ try distributor.setShare(sender, balanceOf(sender)) {} catch {} }
if(!isDividendExempt[recipient]){ try distributor.setShare(recipient, balanceOf(recipient)) {} catch {} }
if(distributionEnabled)
{
try distributor.process(distributorGas) {} catch {}
}
}
function collectFee(uint256 amount, bool sell, bool p2p) private view returns (uint256, uint256, uint256, uint256) {
uint256 _burnFee = amount.mul(p2p ? burnFee[2] : sell ? burnFee[1] : burnFee[0]).div(10000);
uint256 _treasuryFee = amount.mul(p2p ? treasuryFee[2] : sell ? treasuryFee[1] : treasuryFee[0]).div(10000);
uint256 _stakingFee = amount.mul(p2p ? stakingPoolFee[2] : sell ? stakingPoolFee[1] : stakingPoolFee[0]).div(10000);
uint256 _liqudityFee = amount.mul(p2p ? liqudityFee[2] : sell ? liqudityFee[1] : liqudityFee[0]).div(10000);
return (_burnFee, _treasuryFee, _stakingFee, _liqudityFee);
}
function setIsDividendExempt(address holder, bool exempt) external onlyOwner {
isDividendExempt[holder] = exempt;
if(exempt)
{
distributor.setShare(holder, 0);
}
else
{
distributor.setShare(holder, balanceOf(holder));
}
}
function setDistributionStatus(bool status) external onlyOwner {
distributionEnabled = status;
}
function setDistributionCriteria(uint256 minPeriod, uint256 minDistribution) external onlyOwner {
distributor.setDistributionCriteria(minPeriod, minDistribution);
}
function setDistributorGas(uint256 gas) external onlyOwner {
require(gas < 750000, "Gas is greater than limit");
distributorGas = gas;
}
function depositAirDropUSDT(uint256 amount) public{
require(USDT.balanceOf(msg.sender) >= amount, "USDT balance not found on sender address");
USDT.transferFrom(msg.sender, distributorAddress, amount);
distributor.depositUSDT(amount);
}
}
// SPDX-License-Identifier: MIT
pragma solidity 0.8.2;
interface IUniswapV2Factory {
function createPair(address tokenA, address tokenB) external returns (address pair);
}
interface IUniswapV2Router01 {
function factory() external pure returns (address);
function WETH() external pure returns (address);
function addLiquidityETH(address token, uint amountTokenDesired, uint amountTokenMin, uint amountETHMin, address to, uint deadline) external payable returns (uint amountToken, uint amountETH, uint liquidity);
}
interface IUniswapV2Router02 is IUniswapV2Router01 {
function swapExactTokensForETHSupportingFeeOnTransferTokens(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline) external;
}
// SPDX-License-Identifier: MIT
pragma solidity 0.8.2;
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
interface IAirDropDistributor {
function setDistributionCriteria(uint256 _minPeriod, uint256 _minDistribution) external;
function setShare(address shareholder, uint256 amount) external;
function depositUSDT(uint256 amount) external;
function process(uint256 gas) external;
}
contract AirDrop is IAirDropDistributor {
using SafeMath for uint256;
using SafeERC20 for IERC20;
address _token;
struct Share {
uint256 amount;
uint256 totalExcluded;
uint256 totalRealised;
}
IERC20 USDT = IERC20(0xdAC17F958D2ee523a2206206994597C13D831ec7);
address[] shareholders;
mapping (address => uint256) shareholderIndexes;
mapping (address => uint256) shareholderClaims;
mapping (address => Share) public shares;
event DistributionCriteriaUpdate(uint256 minPeriod, uint256 minDistribution);
event NewFundDeposit(uint256 amount);
uint256 public totalShares;
uint256 public totalDividends;
uint256 public totalDistributed;
uint256 public dividendsPerShare;
uint256 public constant dividendsPerShareAccuracyFactor = 10 ** 36;
uint256 public minPeriod = 7 days;
uint256 public minDistribution = 1 * (10 ** 6);
uint256 currentIndex;
modifier onlyToken() {
require(msg.sender == _token, "!Token"); _;
}
constructor () {
_token = msg.sender;
}
function setDistributionCriteria(uint256 _minPeriod, uint256 _minDistribution) external override onlyToken {
minPeriod = _minPeriod;
minDistribution = _minDistribution;
emit DistributionCriteriaUpdate(minPeriod, minDistribution);
}
function setShare(address shareholder, uint256 amount) external override onlyToken {
if(shares[shareholder].amount > 0){
distributeDividend(shareholder);
}
if(amount > 0 && shares[shareholder].amount == 0)
{
addShareholder(shareholder);
}
else if(amount == 0 && shares[shareholder].amount > 0)
{
removeShareholder(shareholder);
}
totalShares = totalShares.sub(shares[shareholder].amount).add(amount);
shares[shareholder].amount = amount;
shares[shareholder].totalExcluded = getCumulativeDividends(shares[shareholder].amount);
}
function depositUSDT(uint256 amount) external override onlyToken {
totalDividends = totalDividends.add(amount);
dividendsPerShare = dividendsPerShare.add(dividendsPerShareAccuracyFactor.mul(amount).div(totalShares));
emit NewFundDeposit(amount);
}
function process(uint256 gas) external override onlyToken {
uint256 shareholderCount = shareholders.length;
if(shareholderCount == 0) { return; }
uint256 gasUsed = 0;
uint256 gasLeft = gasleft();
uint256 iterations = 0;
while(gasUsed < gas && iterations < shareholderCount) {
if(currentIndex >= shareholderCount){
currentIndex = 0;
}
if(shouldDistribute(shareholders[currentIndex])){
distributeDividend(shareholders[currentIndex]);
}
gasUsed = gasUsed.add(gasLeft.sub(gasleft()));
gasLeft = gasleft();
currentIndex++;
iterations++;
}
}
function shouldDistribute(address shareholder) internal view returns (bool) {
return shareholderClaims[shareholder] + minPeriod < block.timestamp && getUnpaidEarnings(shareholder) > minDistribution;
}
function distributeDividend(address shareholder) internal {
if(shares[shareholder].amount == 0){ return; }
uint256 amount = getUnpaidEarnings(shareholder);
if(amount > 0){
totalDistributed = totalDistributed.add(amount);
USDT.transfer(shareholder, amount);
shareholderClaims[shareholder] = block.timestamp;
shares[shareholder].totalRealised = shares[shareholder].totalRealised.add(amount);
shares[shareholder].totalExcluded = getCumulativeDividends(shares[shareholder].amount);
}
}
function claimAirDrop() external {
if(shouldDistribute(msg.sender))
{
distributeDividend(msg.sender);
}
}
function getUnpaidEarnings(address shareholder) public view returns (uint256) {
if(shares[shareholder].amount == 0){ return 0; }
uint256 shareholderTotalDividends = getCumulativeDividends(shares[shareholder].amount);
uint256 shareholderTotalExcluded = shares[shareholder].totalExcluded;
if(shareholderTotalDividends <= shareholderTotalExcluded){ return 0; }
return shareholderTotalDividends.sub(shareholderTotalExcluded);
}
function getCumulativeDividends(uint256 share) internal view returns (uint256) {
return share.mul(dividendsPerShare).div(dividendsPerShareAccuracyFactor);
}
function addShareholder(address shareholder) internal {
shareholderIndexes[shareholder] = shareholders.length;
shareholders.push(shareholder);
}
function removeShareholder(address shareholder) internal {
shareholders[shareholderIndexes[shareholder]] = shareholders[shareholders.length-1];
shareholderIndexes[shareholders[shareholders.length-1]] = shareholderIndexes[shareholder];
shareholders.pop();
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)
pragma solidity ^0.8.0;
import "../utils/Context.sol";
/**
* @dev Contract module which provides a basic access control mechanism, where
* there is an account (an owner) that can be granted exclusive access to
* specific functions.
*
* By default, the owner account will be the one that deploys the contract. This
* can later be changed with {transferOwnership}.
*
* This module is used through inheritance. It will make available the modifier
* `onlyOwner`, which can be applied to your functions to restrict their use to
* the owner.
*/
abstract contract Ownable is Context {
address private _owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
/**
* @dev Initializes the contract setting the deployer as the initial owner.
*/
constructor() {
_transferOwnership(_msgSender());
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
_checkOwner();
_;
}
/**
* @dev Returns the address of the current owner.
*/
function owner() public view virtual returns (address) {
return _owner;
}
/**
* @dev Throws if the sender is not the owner.
*/
function _checkOwner() internal view virtual {
require(owner() == _msgSender(), "Ownable: caller is not the owner");
}
/**
* @dev Leaves the contract without owner. It will not be possible to call
* `onlyOwner` functions anymore. Can only be called by the current owner.
*
* NOTE: Renouncing ownership will leave the contract without an owner,
* thereby removing any functionality that is only available to the owner.
*/
function renounceOwnership() public virtual onlyOwner {
_transferOwnership(address(0));
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Can only be called by the current owner.
*/
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
_transferOwnership(newOwner);
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Internal function without access restriction.
*/
function _transferOwnership(address newOwner) internal virtual {
address oldOwner = _owner;
_owner = newOwner;
emit OwnershipTransferred(oldOwner, newOwner);
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC20/ERC20.sol)
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 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:
*
* - `to` cannot be the zero address.
* - the caller must have a balance of at least `amount`.
*/
function transfer(address to, uint256 amount) public virtual override returns (bool) {
address owner = _msgSender();
_transfer(owner, to, amount);
return true;
}
/**
* @dev See {IERC20-allowance}.
*/
function allowance(address owner, address spender) public view virtual override returns (uint256) {
return _allowances[owner][spender];
}
/**
* @dev See {IERC20-approve}.
*
* NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
* `transferFrom`. This is semantically equivalent to an infinite approval.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 amount) public virtual override returns (bool) {
address owner = _msgSender();
_approve(owner, spender, amount);
return true;
}
/**
* @dev See {IERC20-transferFrom}.
*
* Emits an {Approval} event indicating the updated allowance. This is not
* required by the EIP. See the note at the beginning of {ERC20}.
*
* NOTE: Does not update the allowance if the current allowance
* is the maximum `uint256`.
*
* Requirements:
*
* - `from` and `to` cannot be the zero address.
* - `from` must have a balance of at least `amount`.
* - the caller must have allowance for ``from``'s tokens of at least
* `amount`.
*/
function transferFrom(
address from,
address to,
uint256 amount
) public virtual override returns (bool) {
address spender = _msgSender();
_spendAllowance(from, spender, amount);
_transfer(from, to, amount);
return true;
}
/**
* @dev Atomically increases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
address owner = _msgSender();
_approve(owner, spender, allowance(owner, spender) + addedValue);
return true;
}
/**
* @dev Atomically decreases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
* - `spender` must have allowance for the caller of at least
* `subtractedValue`.
*/
function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
address owner = _msgSender();
uint256 currentAllowance = allowance(owner, spender);
require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
unchecked {
_approve(owner, spender, currentAllowance - subtractedValue);
}
return true;
}
/**
* @dev Moves `amount` of tokens from `from` to `to`.
*
* This internal function is equivalent to {transfer}, and can be used to
* e.g. implement automatic token fees, slashing mechanisms, etc.
*
* Emits a {Transfer} event.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `from` must have a balance of at least `amount`.
*/
function _transfer(
address from,
address to,
uint256 amount
) internal virtual {
require(from != address(0), "ERC20: transfer from the zero address");
require(to != address(0), "ERC20: transfer to the zero address");
_beforeTokenTransfer(from, to, amount);
uint256 fromBalance = _balances[from];
require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
unchecked {
_balances[from] = fromBalance - amount;
}
_balances[to] += amount;
emit Transfer(from, to, amount);
_afterTokenTransfer(from, to, amount);
}
/** @dev Creates `amount` tokens and assigns them to `account`, increasing
* the total supply.
*
* Emits a {Transfer} event with `from` set to the zero address.
*
* Requirements:
*
* - `account` cannot be the zero address.
*/
function _mint(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: mint to the zero address");
_beforeTokenTransfer(address(0), account, amount);
_totalSupply += amount;
_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 Updates `owner` s allowance for `spender` based on spent `amount`.
*
* Does not update the allowance amount in case of infinite allowance.
* Revert if not enough allowance is available.
*
* Might emit an {Approval} event.
*/
function _spendAllowance(
address owner,
address spender,
uint256 amount
) internal virtual {
uint256 currentAllowance = allowance(owner, spender);
if (currentAllowance != type(uint256).max) {
require(currentAllowance >= amount, "ERC20: insufficient allowance");
unchecked {
_approve(owner, spender, currentAllowance - amount);
}
}
}
/**
* @dev Hook that is called before any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* will be transferred to `to`.
* - when `from` is zero, `amount` tokens will be minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens will be burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(
address from,
address to,
uint256 amount
) internal virtual {}
/**
* @dev Hook that is called after any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* has been transferred to `to`.
* - when `from` is zero, `amount` tokens have been minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens have been burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _afterTokenTransfer(
address from,
address to,
uint256 amount
) internal virtual {}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (utils/math/SafeMath.sol)
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 generally not needed starting with Solidity 0.8, since 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 subtraction 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;
}
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC20/utils/SafeERC20.sol)
pragma solidity ^0.8.0;
import "../IERC20.sol";
import "../extensions/draft-IERC20Permit.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));
}
}
function safePermit(
IERC20Permit token,
address owner,
address spender,
uint256 value,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) internal {
uint256 nonceBefore = token.nonces(owner);
token.permit(owner, spender, value, deadline, v, r, s);
uint256 nonceAfter = token.nonces(owner);
require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
}
/**
* @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
// OpenZeppelin Contracts v4.4.1 (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
// OpenZeppelin Contracts (last updated v4.7.0) (utils/Address.sol)
pragma solidity ^0.8.1;
/**
* @dev Collection of functions related to the address type
*/
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* [IMPORTANT]
* ====
* It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*
* Among others, `isContract` will return false for the following
* types of addresses:
*
* - an externally-owned account
* - a contract in construction
* - an address where a contract will be created
* - an address where a contract lived, but was destroyed
* ====
*
* [IMPORTANT]
* ====
* You shouldn't rely on `isContract` to protect against flash loan attacks!
*
* Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
* like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
* constructor.
* ====
*/
function isContract(address account) internal view returns (bool) {
// This method relies on extcodesize/address.code.length, which returns 0
// for contracts in construction, since the code is only stored at the end
// of the constructor execution.
return account.code.length > 0;
}
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
*
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* imposed by `transfer`, making them unable to receive funds via
* `transfer`. {sendValue} removes this limitation.
*
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
(bool success, ) = recipient.call{value: amount}("");
require(success, "Address: unable to send value, recipient may have reverted");
}
/**
* @dev Performs a Solidity function call using a low level `call`. A
* plain `call` is an unsafe replacement for a function call: use this
* function instead.
*
* If `target` reverts with a revert reason, it is bubbled up by this
* function (like regular Solidity function calls).
*
* Returns the raw returned data. To convert to the expected return value,
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
*
* Requirements:
*
* - `target` must be a contract.
* - calling `target` with `data` must not revert.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
return functionCallWithValue(target, data, 0, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but also transferring `value` wei to `target`.
*
* Requirements:
*
* - the calling contract must have an ETH balance of at least `value`.
* - the called Solidity function must be `payable`.
*
* _Available since v3.1._
*/
function functionCallWithValue(
address target,
bytes memory data,
uint256 value
) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
/**
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* with `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCallWithValue(
address target,
bytes memory data,
uint256 value,
string memory errorMessage
) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
require(isContract(target), "Address: call to non-contract");
(bool success, bytes memory returndata) = target.call{value: value}(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(
address target,
bytes memory data,
string memory errorMessage
) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
(bool success, bytes memory returndata) = target.staticcall(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
(bool success, bytes memory returndata) = target.delegatecall(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
* revert reason using the provided one.
*
* _Available since v4.3._
*/
function verifyCallResult(
bool success,
bytes memory returndata,
string memory errorMessage
) internal pure returns (bytes memory) {
if (success) {
return returndata;
} else {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
/// @solidity memory-safe-assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)
pragma solidity ^0.8.0;
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
interface IERC20 {
/**
* @dev Emitted when `value` tokens are moved from one account (`from`) to
* another (`to`).
*
* Note that `value` may be zero.
*/
event Transfer(address indexed from, address indexed to, uint256 value);
/**
* @dev Emitted when the allowance of a `spender` for an `owner` is set by
* a call to {approve}. `value` is the new allowance.
*/
event Approval(address indexed owner, address indexed spender, uint256 value);
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns the amount of tokens owned by `account`.
*/
function balanceOf(address account) external view returns (uint256);
/**
* @dev Moves `amount` tokens from the caller's account to `to`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transfer(address to, uint256 amount) external returns (bool);
/**
* @dev Returns the remaining number of tokens that `spender` will be
* allowed to spend on behalf of `owner` through {transferFrom}. This is
* zero by default.
*
* This value changes when {approve} or {transferFrom} are called.
*/
function allowance(address owner, address spender) external view returns (uint256);
/**
* @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* IMPORTANT: Beware that changing an allowance with this method brings the risk
* that someone may use both the old and the new allowance by unfortunate
* transaction ordering. One possible solution to mitigate this race
* condition is to first reduce the spender's allowance to 0 and set the
* desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
*
* Emits an {Approval} event.
*/
function approve(address spender, uint256 amount) external returns (bool);
/**
* @dev Moves `amount` tokens from `from` to `to` using the
* allowance mechanism. `amount` is then deducted from the caller's
* allowance.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transferFrom(
address from,
address to,
uint256 amount
) external returns (bool);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (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
// OpenZeppelin Contracts v4.4.1 (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);
}