Transaction Hash:
Block:
20981510 at Oct-16-2024 11:49:59 PM +UTC
Transaction Fee:
0.000341865588600713 ETH
$0.78
Gas Used:
46,307 Gas / 7.382589859 Gwei
Emitted Events:
357 |
MoonBag.Approval( owner=[Sender] 0x687873cbe4268e6d53e0304e185c5fe648a870ff, spender=0x40aA958d...a374bcD7f, value=87670000000000000000000 )
|
Account State Difference:
Address | Before | After | State Difference | ||
---|---|---|---|---|---|
0x687873cB...648A870Ff |
0.000367566932866018 Eth
Nonce: 7
|
0.000025701344265305 Eth
Nonce: 8
| 0.000341865588600713 | ||
0x95222290...5CC4BAfe5
Miner
| (beaverbuild) | 7.720178832761303871 Eth | 7.720178837392003871 Eth | 0.0000000046307 | |
0xa7F4195F...657A6c6e4 |
Execution Trace
MoonBag.approve( spender=0x40aA958dd87FC8305b97f2BA922CDdCa374bcD7f, amount=87670000000000000000000 ) => ( True )
approve[MoonBag (ln:704)]
_msgSender[MoonBag (ln:705)]
_approve[MoonBag (ln:706)]
Approval[MoonBag (ln:779)]
// SPDX-License-Identifier: MIT // OpenZeppelin Contracts (last updated v4.9.0) (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. Can only be called by the current owner. * * NOTE: Renouncing ownership will leave the contract without an owner, * thereby disabling 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); } // SPDX-License-Identifier: MIT // OpenZeppelin Contracts (last updated v4.9.4) (token/ERC20/extensions/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. * * ==== Security Considerations * * There are two important considerations concerning the use of `permit`. The first is that a valid permit signature * expresses an allowance, and it should not be assumed to convey additional meaning. In particular, it should not be * considered as an intention to spend the allowance in any specific way. The second is that because permits have * built-in replay protection and can be submitted by anyone, they can be frontrun. A protocol that uses permits should * take this into consideration and allow a `permit` call to fail. Combining these two aspects, a pattern that may be * generally recommended is: * * ```solidity * function doThingWithPermit(..., uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) public { * try token.permit(msg.sender, address(this), value, deadline, v, r, s) {} catch {} * doThing(..., value); * } * * function doThing(..., uint256 value) public { * token.safeTransferFrom(msg.sender, address(this), value); * ... * } * ``` * * Observe that: 1) `msg.sender` is used as the owner, leaving no ambiguity as to the signer intent, and 2) the use of * `try/catch` allows the permit to fail and makes the code tolerant to frontrunning. (See also * {SafeERC20-safeTransferFrom}). * * Additionally, note that smart contract wallets (such as Argent or Safe) are not able to produce permit signatures, so * contracts should have entry points that don't rely on permit. */ 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]. * * CAUTION: See Security Considerations above. */ 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 v4.9.0) (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 v4.9.3) (token/ERC20/utils/SafeERC20.sol) pragma solidity ^0.8.0; import "../IERC20.sol"; import "../extensions/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; /** * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value, * non-reverting calls are assumed to be successful. */ function safeTransfer(IERC20 token, address to, uint256 value) internal { _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value)); } /** * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful. */ 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)); } /** * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value, * non-reverting calls are assumed to be successful. */ function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal { uint256 oldAllowance = token.allowance(address(this), spender); _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance + value)); } /** * @dev Decrease the calling contract's allowance toward `spender` by `value`. If `token` returns no value, * non-reverting calls are assumed to be successful. */ 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"); _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance - value)); } } /** * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value, * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval * to be set to zero before setting it to a non-zero value, such as USDT. */ function forceApprove(IERC20 token, address spender, uint256 value) internal { bytes memory approvalCall = abi.encodeWithSelector(token.approve.selector, spender, value); if (!_callOptionalReturnBool(token, approvalCall)) { _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, 0)); _callOptionalReturn(token, approvalCall); } } /** * @dev Use a ERC-2612 signature to set the `owner` approval toward `spender` on `token`. * Revert on invalid signature. */ 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"); require(returndata.length == 0 || abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation 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). * * This is a variant of {_callOptionalReturn} that silents catches all reverts and returns a bool instead. */ function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) { // 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 cannot use {Address-functionCall} here since this should return false // and not revert is the subcall reverts. (bool success, bytes memory returndata) = address(token).call(data); return success && (returndata.length == 0 || abi.decode(returndata, (bool))) && Address.isContract(address(token)); } } // SPDX-License-Identifier: MIT // OpenZeppelin Contracts (last updated v4.9.0) (utils/Address.sol) pragma solidity ^0.8.1; /** * @dev Collection of functions related to the address type */ library 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 * * Furthermore, `isContract` will also return true if the target contract within * the same transaction is already scheduled for destruction by `SELFDESTRUCT`, * which only has an effect at the end of a transaction. * ==== * * [IMPORTANT] * ==== * You shouldn't rely on `isContract` to protect against flash loan attacks! * * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract * constructor. * ==== */ function isContract(address account) internal view returns (bool) { // This method relies on extcodesize/address.code.length, which returns 0 // for contracts in construction, since the code is only stored at the end // of the constructor execution. return account.code.length > 0; } /** * @dev Replacement for Solidity's `transfer`: sends `amount` wei to * `recipient`, forwarding all available gas and reverting on errors. * * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost * of certain opcodes, possibly making contracts go over the 2300 gas limit * imposed by `transfer`, making them unable to receive funds via * `transfer`. {sendValue} removes this limitation. * * https://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/[Learn more]. * * IMPORTANT: because control is transferred to `recipient`, care must be * taken to not create reentrancy vulnerabilities. Consider using * {ReentrancyGuard} or the * https://solidity.readthedocs.io/en/v0.8.0/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern]. */ function sendValue(address payable recipient, uint256 amount) internal { require(address(this).balance >= amount, "Address: insufficient balance"); (bool success, ) = recipient.call{value: amount}(""); require(success, "Address: unable to send value, recipient may have reverted"); } /** * @dev Performs a Solidity function call using a low level `call`. A * plain `call` is an unsafe replacement for a function call: use this * function instead. * * If `target` reverts with a revert reason, it is bubbled up by this * function (like regular Solidity function calls). * * Returns the raw returned data. To convert to the expected return value, * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`]. * * Requirements: * * - `target` must be a contract. * - calling `target` with `data` must not revert. * * _Available since v3.1._ */ function functionCall(address target, bytes memory data) internal returns (bytes memory) { return functionCallWithValue(target, data, 0, "Address: low-level call failed"); } /** * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with * `errorMessage` as a fallback revert reason when `target` reverts. * * _Available since v3.1._ */ function functionCall( address target, bytes memory data, string memory errorMessage ) internal returns (bytes memory) { return functionCallWithValue(target, data, 0, errorMessage); } /** * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], * but also transferring `value` wei to `target`. * * Requirements: * * - the calling contract must have an ETH balance of at least `value`. * - the called Solidity function must be `payable`. * * _Available since v3.1._ */ function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) { return functionCallWithValue(target, data, value, "Address: low-level call with value failed"); } /** * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but * with `errorMessage` as a fallback revert reason when `target` reverts. * * _Available since v3.1._ */ function functionCallWithValue( address target, bytes memory data, uint256 value, string memory errorMessage ) internal returns (bytes memory) { require(address(this).balance >= value, "Address: insufficient balance for call"); (bool success, bytes memory returndata) = target.call{value: value}(data); return verifyCallResultFromTarget(target, success, returndata, errorMessage); } /** * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], * but performing a static call. * * _Available since v3.3._ */ function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) { return functionStaticCall(target, data, "Address: low-level static call failed"); } /** * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`], * but performing a static call. * * _Available since v3.3._ */ function functionStaticCall( address target, bytes memory data, string memory errorMessage ) internal view returns (bytes memory) { (bool success, bytes memory returndata) = target.staticcall(data); return verifyCallResultFromTarget(target, success, returndata, errorMessage); } /** * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], * but performing a delegate call. * * _Available since v3.4._ */ function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) { return functionDelegateCall(target, data, "Address: low-level delegate call failed"); } /** * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`], * but performing a delegate call. * * _Available since v3.4._ */ function functionDelegateCall( address target, bytes memory data, string memory errorMessage ) internal returns (bytes memory) { (bool success, bytes memory returndata) = target.delegatecall(data); return verifyCallResultFromTarget(target, success, returndata, errorMessage); } /** * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract. * * _Available since v4.8._ */ function verifyCallResultFromTarget( address target, bool success, bytes memory returndata, string memory errorMessage ) internal view returns (bytes memory) { if (success) { if (returndata.length == 0) { // only check isContract if the call was successful and the return data is empty // otherwise we already know that it was a contract require(isContract(target), "Address: call to non-contract"); } return returndata; } else { _revert(returndata, errorMessage); } } /** * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the * revert reason or using the provided one. * * _Available since v4.3._ */ function verifyCallResult( bool success, bytes memory returndata, string memory errorMessage ) internal pure returns (bytes memory) { if (success) { return returndata; } else { _revert(returndata, errorMessage); } } function _revert(bytes memory returndata, string memory errorMessage) private pure { // Look for revert reason and bubble it up if present if (returndata.length > 0) { // The easiest way to bubble the revert reason is using memory via assembly /// @solidity memory-safe-assembly assembly { let returndata_size := mload(returndata) revert(add(32, returndata), returndata_size) } } else { revert(errorMessage); } } } // SPDX-License-Identifier: MIT // OpenZeppelin Contracts (last updated v4.9.4) (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; } function _contextSuffixLength() internal view virtual returns (uint256) { return 0; } } // SPDX-License-Identifier: MIT pragma solidity 0.8.18; import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol"; import "@openzeppelin/contracts/access/Ownable.sol"; import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol"; contract MoonBag is IERC20Metadata, Ownable { using SafeERC20 for IERC20Metadata; mapping(address => uint256) private _balances; mapping(address => mapping(address => uint256)) private _allowances; uint256 private _totalSupply; string private _name; string private _symbol; uint8 private _decimals; constructor( string memory __name, string memory __symbol, uint256 __totalSupply, uint8 __decimals ) { _name = __name; _symbol = __symbol; _decimals = __decimals; _mint(_msgSender(), __totalSupply); } /** * @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; } function decimals() public view virtual override returns (uint8) { return _decimals; } /** * @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]; } function approve(address spender, uint256 amount) public virtual override returns (bool) { address owner = _msgSender(); _approve(owner, spender, amount); return true; } 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; } function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) { address owner = _msgSender(); _approve(owner, spender, allowance(owner, spender) + addedValue); return true; } function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) { address owner = _msgSender(); uint256 currentAllowance = allowance(owner, spender); require(currentAllowance >= subtractedValue, "ERC20:allowance<0"); unchecked { _approve(owner, spender, currentAllowance - subtractedValue); } return true; } function _transfer( address from, address to, uint256 amount ) internal virtual { require(from != address(0), "ERC20:From 0"); require(to != address(0), "ERC20:To 0"); uint256 fromBalance = _balances[from]; require(fromBalance >= amount, "ERC20:amount>balance"); unchecked { _balances[from] = fromBalance - amount; _balances[to] += amount; } emit Transfer(from, to, amount); } function _mint(address account, uint256 amount) internal virtual { require(account != address(0), "ERC20:address(0)"); _totalSupply += amount; unchecked { _balances[account] += amount; } emit Transfer(address(0), account, amount); } function _burn(address account, uint256 amount) internal virtual { require(account != address(0), "ERC20:address(0)"); uint256 accountBalance = _balances[account]; require(accountBalance >= amount, "ERC20:amount>balance"); unchecked { _balances[account] = accountBalance - amount; // Overflow not possible: amount <= accountBalance <= totalSupply. _totalSupply -= amount; } emit Transfer(account, address(0), amount); } function _approve( address owner, address spender, uint256 amount ) internal virtual { require(owner != address(0), "ERC20:FromAddress(0)"); require(spender != address(0), "ERC20:ToAddress(0)"); _allowances[owner][spender] = amount; emit Approval(owner, spender, amount); } 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); } } } function withdrawToken(address _token) external onlyOwner { IERC20Metadata(_token).safeTransfer(owner(), IERC20Metadata(_token).balanceOf(address(this))); } }