Contract Source Code:
// SPDX-License-Identifier: MIT
// sojoswap.com
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
pragma solidity 0.8.15;
interface IDexRouter {
function factory() external pure returns (address);
function WETH() external pure returns (address);
function swapExactTokensForETHSupportingFeeOnTransferTokens(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline) external;
function addLiquidityETH(address token, uint256 amountTokenDesired, uint256 amountTokenMin, uint256 amountETHMin, address to, uint256 deadline) external payable returns (uint256 amountToken, uint256 amountETH, uint256 liquidity);
}
interface IDexFactory {
function createPair(address tokenA, address tokenB) external returns (address pair);
}
contract Sojourner is ERC20, Ownable {
uint256 public maxBuyAmount;
uint256 public maxSellAmount;
uint256 public maxWallet;
IDexRouter public dexRouter;
address public lpPair;
bool private swapping;
uint256 public swapTokensAtAmount;
address public devAddress;
bool public limitsInEffect = true;
bool public tradingActive = false;
bool public swapEnabled = false;
// Anti-bot and anti-whale mappings and variables
mapping(address => uint256) private _holderLastTransferTimestamp; // to hold last Transfers temporarily during launch
bool public transferDelayEnabled = true;
uint256 public buyTotalFees;
uint256 public buyDevFee;
uint256 public buyLiquidityFee;
uint256 public buyBurnFee;
uint256 public sellTotalFees;
uint256 public sellDevFee;
uint256 public sellLiquidityFee;
uint256 public sellBurnFee;
uint256 public constant FEE_DIVISOR = 1000;
uint256 public tokensForDev;
uint256 public tokensForLiquidity;
mapping (address => bool) private _isExcludedFromFees;
mapping (address => bool) public _isExcludedMaxTransactionAmount;
mapping (address => bool) public automatedMarketMakerPairs;
event SetAutomatedMarketMakerPair(address indexed pair, bool indexed value);
event EnabledTrading();
event RemovedLimits();
event ExcludeFromFees(address indexed account, bool isExcluded);
event UpdatedMaxBuyAmount(uint256 newAmount);
event UpdatedMaxSellAmount(uint256 newAmount);
event UpdatedMaxWalletAmount(uint256 newAmount);
event UpdatedDevAddress(address indexed newWallet);
event MaxTransactionExclusion(address _address, bool excluded);
event OwnerForcedSwapBack(uint256 timestamp);
event SwapAndLiquify(
uint256 tokensSwapped,
uint256 ethReceived,
uint256 tokensIntoLiquidity
);
constructor(string memory name_, string memory symbol_, uint256 totalSupply_) ERC20(name_, symbol_) payable {
address newOwner = msg.sender; // can leave alone if owner is deployer.
address _dexRouter;
if(block.chainid == 1 || block.chainid == 5){
_dexRouter = 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D; // ETH: Uniswap V2
} else if(block.chainid == 42161){
_dexRouter = 0x1b02dA8Cb0d097eB8D57A175b88c7D8b47997506; // Arbitrum: SushiSwap
} else {
revert("Chain not configured");
}
// initialize router
dexRouter = IDexRouter(_dexRouter);
uint256 totalSupply = totalSupply_ * (10 ** decimals());
maxBuyAmount = totalSupply * 1 / 1000;
maxSellAmount = totalSupply * 10 / 1000;
maxWallet = totalSupply * 10 / 1000;
swapTokensAtAmount = totalSupply * 25 / 100000;
buyDevFee = 30;
buyLiquidityFee = 10;
buyBurnFee = 10;
buyTotalFees = buyDevFee + buyLiquidityFee + buyBurnFee;
sellDevFee = 30;
sellLiquidityFee = 10;
sellBurnFee = 10;
sellTotalFees = sellDevFee + sellLiquidityFee + sellBurnFee;
devAddress = address(msg.sender);
_excludeFromMaxTransaction(newOwner, true);
_excludeFromMaxTransaction(address(this), true);
_excludeFromMaxTransaction(address(0xdead), true);
_excludeFromMaxTransaction(address(devAddress), true);
_excludeFromMaxTransaction(address(dexRouter), true);
excludeFromFees(newOwner, true);
excludeFromFees(address(this), true);
excludeFromFees(address(0xdead), true);
excludeFromFees(address(devAddress), true);
excludeFromFees(address(dexRouter), true);
_mint(msg.sender, totalSupply);
transferOwnership(newOwner);
}
receive() external payable {}
function enableTrading() external onlyOwner {
require(!tradingActive, "Cannot reenable trading");
tradingActive = true;
swapEnabled = true;
emit EnabledTrading();
}
// remove limits after token is stable
function removeLimits() external onlyOwner {
limitsInEffect = false;
transferDelayEnabled = false;
maxBuyAmount = totalSupply();
maxSellAmount = totalSupply();
emit RemovedLimits();
}
function emergencyUpdateRouter(address router) external onlyOwner {
require(!tradingActive, "Cannot update after trading is functional");
dexRouter = IDexRouter(router);
}
// disable Transfer delay - cannot be reenabled
function disableTransferDelay() external onlyOwner {
transferDelayEnabled = false;
}
function updateMaxBuyAmount(uint256 newNum) external onlyOwner {
require(newNum >= 1, "Cannot set max buy amount lower than 0.1%");
maxBuyAmount = totalSupply() * newNum / 1000;
emit UpdatedMaxBuyAmount(maxBuyAmount);
}
function updateMaxSellAmount(uint256 newNum) external onlyOwner {
require(newNum >= 1, "Cannot set max sell amount lower than 0.1%");
maxSellAmount = totalSupply() * newNum / 1000;
emit UpdatedMaxSellAmount(maxSellAmount);
}
function updateMaxWallet(uint256 newNum) external onlyOwner {
require(newNum >= 1, "Cannot set max wallet amount lower than %");
maxWallet = totalSupply() * newNum / 1000;
emit UpdatedMaxWalletAmount(maxWallet);
}
// change the minimum amount of tokens to sell from fees
function updateSwapTokensAtAmount(uint256 newAmount) external onlyOwner {
require(newAmount >= totalSupply() * 1 / 100000, "Swap amount cannot be lower than 0.001% total supply.");
require(newAmount <= totalSupply() * 1 / 1000, "Swap amount cannot be higher than 0.1% total supply.");
swapTokensAtAmount = newAmount;
}
function _excludeFromMaxTransaction(address updAds, bool isExcluded) private {
_isExcludedMaxTransactionAmount[updAds] = isExcluded;
emit MaxTransactionExclusion(updAds, isExcluded);
}
function excludeFromMaxTransaction(address updAds, bool isEx) external onlyOwner {
if(!isEx){
require(updAds != lpPair, "Cannot remove uniswap pair from max txn");
}
_isExcludedMaxTransactionAmount[updAds] = isEx;
}
function setAutomatedMarketMakerPair(address pair, bool value) external onlyOwner {
require(pair != lpPair, "The pair cannot be removed from automatedMarketMakerPairs");
_setAutomatedMarketMakerPair(pair, value);
emit SetAutomatedMarketMakerPair(pair, value);
}
function _setAutomatedMarketMakerPair(address pair, bool value) private {
automatedMarketMakerPairs[pair] = value;
_excludeFromMaxTransaction(pair, value);
emit SetAutomatedMarketMakerPair(pair, value);
}
function updateBuyFees(uint256 _devFee, uint256 _liquidityFee, uint256 _burnFee) external onlyOwner {
buyDevFee = _devFee;
buyLiquidityFee = _liquidityFee;
buyBurnFee = _burnFee;
buyTotalFees = buyDevFee + buyLiquidityFee + buyBurnFee;
require(buyTotalFees <= 10 * FEE_DIVISOR / 100, "Must keep fees at 10% or less");
}
function updateSellFees(uint256 _devFee, uint256 _liquidityFee,uint256 _burnFee) external onlyOwner {
sellDevFee = _devFee;
sellLiquidityFee = _liquidityFee;
sellBurnFee = _burnFee;
sellTotalFees = sellDevFee + sellLiquidityFee + sellBurnFee;
require(sellTotalFees <= 20 * FEE_DIVISOR / 100, "Must keep fees at 20% or less");
}
function massExcludeFromFees(address[] calldata accounts, bool excluded) external onlyOwner {
for(uint256 i = 0; i < accounts.length; i++){
_isExcludedFromFees[accounts[i]] = excluded;
emit ExcludeFromFees(accounts[i], excluded);
}
}
function excludeFromFees(address account, bool excluded) public onlyOwner {
_isExcludedFromFees[account] = excluded;
emit ExcludeFromFees(account, excluded);
}
function _transfer(address from, address to, uint256 amount) internal override {
require(from != address(0), "ERC20: transfer from the zero address");
require(to != address(0), "ERC20: transfer to the zero address");
require(amount > 0, "amount must be greater than 0");
if(!tradingActive){
require(_isExcludedFromFees[from] || _isExcludedFromFees[to], "Trading is not active.");
}
if(limitsInEffect){
if (from != owner() && to != owner() && to != address(0) && to != address(0xdead) && !_isExcludedFromFees[from] && !_isExcludedFromFees[to]){
// at launch if the transfer delay is enabled, ensure the block timestamps for purchasers is set -- during launch.
if (transferDelayEnabled){
if (to != address(dexRouter) && to != address(lpPair)){
require(_holderLastTransferTimestamp[tx.origin] < block.number - 2 && _holderLastTransferTimestamp[to] < block.number - 2, "_transfer:: Transfer Delay enabled. Try again later.");
_holderLastTransferTimestamp[tx.origin] = block.number;
_holderLastTransferTimestamp[to] = block.number;
}
}
//when buy
if (automatedMarketMakerPairs[from] && !_isExcludedMaxTransactionAmount[to]) {
require(amount <= maxBuyAmount, "Buy transfer amount exceeds the max buy.");
require(amount + balanceOf(to) <= maxWallet, "Cannot exceed max wallet");
}
//when sell
else if (automatedMarketMakerPairs[to] && !_isExcludedMaxTransactionAmount[from]) {
require(amount <= maxSellAmount, "Sell transfer amount exceeds the max sell.");
}
else if (!_isExcludedMaxTransactionAmount[to]) {
require(amount + balanceOf(to) <= maxWallet, "Cannot exceed max wallet");
}
}
}
uint256 contractTokenBalance = balanceOf(address(this));
bool canSwap = contractTokenBalance >= swapTokensAtAmount;
if(canSwap && swapEnabled && !swapping && !automatedMarketMakerPairs[from] && !_isExcludedFromFees[from] && !_isExcludedFromFees[to]) {
swapping = true;
swapBack();
swapping = false;
}
bool takeFee = true;
// if any account belongs to _isExcludedFromFee account then remove the fee
if(_isExcludedFromFees[from] || _isExcludedFromFees[to]) {
takeFee = false;
}
uint256 fees = 0;
uint256 tokensToBurn = 0;
// only take fees on buys/sells, do not take on wallet transfers
if(takeFee){
// on sell
if (automatedMarketMakerPairs[to] && sellTotalFees > 0){
fees = amount * sellTotalFees / FEE_DIVISOR;
tokensForLiquidity += fees * sellLiquidityFee / sellTotalFees;
tokensForDev += fees * sellDevFee / sellTotalFees;
tokensToBurn = fees * sellBurnFee / buyTotalFees;
}
// on buy
else if(automatedMarketMakerPairs[from] && buyTotalFees > 0) {
fees = amount * buyTotalFees / FEE_DIVISOR;
tokensForLiquidity += fees * buyLiquidityFee / buyTotalFees;
tokensForDev += fees * buyDevFee / buyTotalFees;
tokensToBurn = fees * buyBurnFee / buyTotalFees;
}
if(fees > 0){
super._transfer(from, address(this), fees);
if(tokensToBurn > 0){
super._transfer(address(this), address(0xdead), tokensToBurn);
}
}
amount -= fees;
}
super._transfer(from, to, amount);
}
function swapTokensForEth(uint256 tokenAmount) private {
// generate the uniswap pair path of token -> weth
address[] memory path = new address[](2);
path[0] = address(this);
path[1] = dexRouter.WETH();
_approve(address(this), address(dexRouter), tokenAmount);
// make the swap
dexRouter.swapExactTokensForETHSupportingFeeOnTransferTokens(
tokenAmount,
0, // accept any amount of ETH
path,
address(this),
block.timestamp
);
}
function addLiquidity(uint256 tokenAmount, uint256 ethAmount) private {
// approve token transfer to cover all possible scenarios
_approve(address(this), address(dexRouter), tokenAmount);
// add the liquidity
dexRouter.addLiquidityETH{value: ethAmount}(
address(this),
tokenAmount,
0, // slippage is unavoidable
0, // slippage is unavoidable
address(this),
block.timestamp
);
}
function swapBack() private {
uint256 contractBalance = balanceOf(address(this));
uint256 totalTokensToSwap = tokensForLiquidity + tokensForDev;
if(contractBalance == 0 || totalTokensToSwap == 0) {return;}
if(contractBalance > swapTokensAtAmount * 10){
contractBalance = swapTokensAtAmount * 10;
}
bool success;
// Halve the amount of liquidity tokens
uint256 liquidityTokens = contractBalance * tokensForLiquidity / totalTokensToSwap / 2;
swapTokensForEth(contractBalance - liquidityTokens);
uint256 ethBalance = address(this).balance;
uint256 ethForLiquidity = ethBalance;
uint256 ethForDev = ethBalance * tokensForDev / (totalTokensToSwap - (tokensForLiquidity/2));
ethForLiquidity -= ethForDev;
tokensForLiquidity = 0;
tokensForDev = 0;
if(liquidityTokens > 0 && ethForLiquidity > 0){
addLiquidity(liquidityTokens, ethForLiquidity);
}
(success,) = address(devAddress).call{value: address(this).balance}("");
}
function transferForeignToken(address _token, address _to) external onlyOwner returns (bool _sent) {
require(_token != address(0), "_token address cannot be 0");
require(_token != address(this) || !tradingActive, "Can't withdraw native tokens while trading is active");
uint256 _contractBalance = IERC20(_token).balanceOf(address(this));
_sent = IERC20(_token).transfer(_to, _contractBalance);
}
// withdraw ETH if stuck or someone sends to the address
function withdrawStuckETH() external onlyOwner {
bool success;
(success,) = address(msg.sender).call{value: address(this).balance}("");
}
function setDevAddress(address _devAddress) external onlyOwner {
require(_devAddress != address(0), "_devAddress address cannot be 0");
devAddress = payable(_devAddress);
}
// force Swap back if slippage issues.
function forceSwapBack() external onlyOwner {
require(balanceOf(address(this)) >= swapTokensAtAmount, "Can only swap when token amount is at or higher than restriction");
swapping = true;
swapBack();
swapping = false;
emit OwnerForcedSwapBack(block.timestamp);
}
function launch() external onlyOwner {
require(!tradingActive, "Trading is already active, cannot relaunch.");
//standard enable trading
tradingActive = true;
swapEnabled = true;
emit EnabledTrading();
// create pair
lpPair = IDexFactory(dexRouter.factory()).createPair(address(this), dexRouter.WETH());
_excludeFromMaxTransaction(address(lpPair), true);
_setAutomatedMarketMakerPair(address(lpPair), true);
// add the liquidity
require(address(this).balance > 0, "Must have ETH on contract to launch");
require(balanceOf(address(this)) > 0, "Must have Tokens on contract to launch");
_approve(address(this), address(dexRouter), balanceOf(address(this)));
dexRouter.addLiquidityETH{value: address(this).balance}(
address(this),
balanceOf(address(this)),
0, // slippage is unavoidable
0, // slippage is unavoidable
address(msg.sender),
block.timestamp
);
}
}
// 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 (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 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 (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 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);
}