Transaction Hash:
Block:
20049293 at Jun-08-2024 07:47:35 PM +UTC
Transaction Fee:
0.014723788850734647 ETH
$35.92
Gas Used:
1,416,991 Gas / 10.390883817 Gwei
Emitted Events:
26 |
0x6f11fb4d4178c5d5e3ee4bc7820d8cfed0b59ce7.0x00ed5939179dc194223f0edd1517ecee2210b22da7f82c8e4b1795e93b9f06aa( 0x00ed5939179dc194223f0edd1517ecee2210b22da7f82c8e4b1795e93b9f06aa, 0000000000000000000000000000000000000000000000000000000000000000, 00000000000000000000000046762bde09c1a1c566c3efd959368455bf20c354, 000000000000000000000000000000000000000000000000001550f7dca70000 )
|
27 |
0x148acd3cd4d6a17cd2abbecd0745b09b62c64f84.0x00ed5939179dc194223f0edd1517ecee2210b22da7f82c8e4b1795e93b9f06aa( 0x00ed5939179dc194223f0edd1517ecee2210b22da7f82c8e4b1795e93b9f06aa, 0x0000000000000000000000000000000000000000000000000000000000000000, 0x00000000000000000000000046762bde09c1a1c566c3efd959368455bf20c354, 000000000000000000000000000000000000000000000000001550f7dca70000 )
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28 |
ERC20Token.Transfer( from=0x0000000000000000000000000000000000000000, to=0x46762bdE09C1a1c566c3efD959368455Bf20c354, value=2191200 )
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29 |
0xd856f0f9efa054896fe3596e05978bbe686de131.0xdfdcfe14b965674fff33e543e57c9e0150c14e72485a82b8ee0d20bf1f243a0b( 0xdfdcfe14b965674fff33e543e57c9e0150c14e72485a82b8ee0d20bf1f243a0b, 0x00000000000000000000000000000000000000000000000000000000000000d6, 0xb483afd3f4caedc6eebf44246fe54e38c95e3179a5ec9ea81740eca5b482d12e, 0xd724d9c2f62549b9d81846f9a9a1a2756834829a4b1c2e52f04e8ceacade59db, 0000000000000000000000000000000000000000000000000000000000000100, 0000000000000000000000000000000000000000000000000000000000000140, 0000000000000000000000000000000000000000000000000000000000000180, 00000000000000000000000000000000000000000000000000000000000001c0, 0000000000000000000000000000000000000000000000000000000000000200, 0000000000000000000000000000000000000000000000000000000000000001, 000000000000000000000000000000000000000000000000000000000131f52d, 00000000000000000000000000000000000000000000000017d6ca1c55c08bc0, 0000000000000000000000000000000000000000000000000000000000000008, 7472616e73666572000000000000000000000000000000000000000000000000, 0000000000000000000000000000000000000000000000000000000000000009, 6368616e6e656c2d320000000000000000000000000000000000000000000000, 0000000000000000000000000000000000000000000000000000000000000008, 7472616e73666572000000000000000000000000000000000000000000000000, 000000000000000000000000000000000000000000000000000000000000000a, 6368616e6e656c2d353200000000000000000000000000000000000000000000, 000000000000000000000000000000000000000000000000000000000000016b, 7b22616d6f756e74223a2232313931323030222c2264656e6f6d223a22747261, 6e736665722f6368616e6e656c2d322f7472616e736665722f6368616e6e656c, 2d352f73747561746f6d222c226d656d6f223a227b5c22666f72776172645c22, 3a7b5c2272656365697665725c223a5c227374726964653165776d3937743571, 7733757574776439716830796479303037796d686c3871743072656530655c22, 2c5c22706f72745c223a5c227472616e736665725c222c5c226368616e6e656c, 5c223a5c226368616e6e656c2d355c222c5c2274696d656f75745c223a363030, 303030303030303030302c5c22726574726965735c223a307d7d222c22726563, 6569766572223a22706963613165776d39377435717733757574776439716830, 796479303037796d686c387174683536716c6a222c2273656e646572223a2230, 7834363736326264653039633161316335363663336566643935393336383435, 356266323063333534227d000000000000000000000000000000000000000000 )
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Account State Difference:
Address | Before | After | State Difference | ||
---|---|---|---|---|---|
0x46762bdE...5Bf20c354 | 0.194872300202949428 Eth | 0.200872300202949428 Eth | 0.006 | ||
0x6c57e54C...B35AC2CB9 | (IBC Protocol: Relayer) |
0.961820328328277612 Eth
Nonce: 1239
|
0.947096539477542965 Eth
Nonce: 1240
| 0.014723788850734647 | |
0x6f11fb4D...ED0b59ce7 | 0.78362280492 Eth | 0.77762280492 Eth | 0.006 | ||
0x95222290...5CC4BAfe5
Miner
| (beaverbuild) | 6.480409426267650474 Eth | 6.484660399267650474 Eth | 0.004250973 | |
0xA534115D...5189a1de2 | |||||
0xd856f0f9...e686De131 |
Execution Trace
0xd856f0f9efa054896fe3596e05978bbe686de131.6de049d6( )
0xa5111b33e465db832ad8ee040c2a8d01cf26f833.6de049d6( )
0xd856f0f9efa054896fe3596e05978bbe686de131.aa18c8b1( )
0xebc4ddeca969572e4891dc2e0e0c7a9c5f2d06fa.aa18c8b1( )
0xa3837753d4599eb6b089ded840cfff63da0f3314.329681d0( )
-
0xdfe34b77af654394add0a6426ebe8aecc2e58dce.329681d0( )
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0xa3837753d4599eb6b089ded840cfff63da0f3314.4b0bbdc4( )
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0xdfe34b77af654394add0a6426ebe8aecc2e58dce.4b0bbdc4( )
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-
Null: 0x000...002.7b22616d( )
-
Null: 0x000...002.17d6ca1c( )
0xa3837753d4599eb6b089ded840cfff63da0f3314.4d2fdeb8( )
0xdfe34b77af654394add0a6426ebe8aecc2e58dce.4d2fdeb8( )
-
0x57f7457d9c4849f4babdb43c84aaa10445b7fb6b.5c45ddd8( )
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0x148acd3cd4d6a17cd2abbecd0745b09b62c64f84.52c7157d( )
0xa919ad106495cb566dd08daa132e054845716724.52c7157d( )
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0x5933fde9fa60d4f1c0124aa7a7a988f46ba42d78.STATICCALL( )
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0x6f11fb4d4178c5d5e3ee4bc7820d8cfed0b59ce7.07b18bde( )
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0x5933fde9fa60d4f1c0124aa7a7a988f46ba42d78.ba7aef43( )
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// SPDX-License-Identifier: Apache-2.0 pragma solidity ^0.8.0; import "@openzeppelin/contracts/token/ERC20/ERC20.sol"; import "@openzeppelin/contracts/access/Ownable.sol"; /** * @title ERC20Token * @dev Implementation of the ERC20 interface with customizable token properties. * This contract extends the ERC20 standard with the ability for the contract owner to * modify token name, symbol, and decimals after deployment. It also includes minting * and burning functionalities controlled by the contract owner. */ contract ERC20Token is ERC20, Ownable { uint8 private _decimals; string private _name; string private _symbol; bool private _isDecimalsSet; uint256 constant internal MAX_DECIMALS = 77; // log10(2^256 - 1) /** * @dev emitted when the decimals are changed by the owner. */ event SetDecimals(uint8 precision); /** * @dev emitted when the name is changed by the owner. */ event SetName(string name); /** * @dev emitted when the symbol is changed by the owner. */ event SetSymbol(string symbol); /** * @dev Constructor for initializing the ERC20Token contract Sets the owner of the contract * to the deployer of the contract. Mints the initial supply of tokens to the deployer. * * Reverts if the number of decimal places is greater than `MAX_DECIMALS`. * @param initialName The name of the token. * @param initialSymbol The symbol of the token. * @param initSupply The initial supply of tokens to mint upon contract deployment. * @param initialDecimals The number of decimal places for the token. */ constructor(string memory initialName, string memory initialSymbol, uint256 initSupply, uint8 initialDecimals) ERC20(initialName, initialSymbol) Ownable(_msgSender()) { _mint(_msgSender(), initSupply); _decimals = initialDecimals; _name = initialName; _symbol = initialSymbol; _isDecimalsSet = false; require(initialDecimals <= MAX_DECIMALS, "ERC20Token: precision too high"); } /** * @notice Mint new tokens. * @dev Mint new tokens to the specified account. Only the owner can call this function. * A `Transfer` event is emitted from the internal `_mint` function. * @param account The account to mint the tokens to. * @param amount The amount of tokens to mint. */ function mint(address account, uint256 amount) external onlyOwner { _mint(account, amount); } /** * @notice Burn tokens. * @dev Burn tokens from the specified account. Only the owner can call this function. * A `Transfer` event is emitted from the internal `_burn` function. * @param account The account to burn the tokens from. * @param amount The amount of tokens to burn. */ function burn(address account, uint256 amount) external onlyOwner { _burn(account, amount); } /** * @notice Set the number of decimal places for the token. * @dev Set the number of decimal places for the token. Only the owner can call this function. * * Reverts if one of the following is true: * - the number of decimal places is already set. * - the new number of decimal places is greater than `MAX_DECIMALS`. * @param newDecimals The number of decimal places for the token. */ function setDecimals(uint8 newDecimals) external onlyOwner { require(!_isDecimalsSet, "ERC20Token: decimals is already set"); require(newDecimals <= MAX_DECIMALS, "ERC20Token: precision too high"); _decimals = newDecimals; _isDecimalsSet = true; emit SetDecimals(newDecimals); } /** * @notice Set the name of the token. * @dev Set the name of the token. Only the owner can call this function. * @param newName The name of the token. */ function setName(string memory newName) external onlyOwner { _name = newName; emit SetName(newName); } /** * @notice Set the symbol of the token. * @dev Set the symbol of the token. Only the owner can call this function. * @param newSymbol The symbol of the token. */ function setSymbol(string memory newSymbol) external onlyOwner { _symbol = newSymbol; emit SetSymbol(newSymbol); } /** * @notice Get the number of decimal places for the token. * @return The number of decimal places for the token. */ function decimals() public view virtual override returns (uint8) { return _decimals; } /** * @notice Get the name of the token. * @return The name of the token. */ function name() public view virtual override returns (string memory) { return _name; } /** * @notice Get the symbol of the token. * @return The symbol of the token. */ function symbol() public view virtual override returns (string memory) { return _symbol; } } // SPDX-License-Identifier: MIT // OpenZeppelin Contracts (last updated v5.0.0) (access/Ownable.sol) pragma solidity ^0.8.20; import {Context} from "../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. * * The initial owner is set to the address provided by the deployer. 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; /** * @dev The caller account is not authorized to perform an operation. */ error OwnableUnauthorizedAccount(address account); /** * @dev The owner is not a valid owner account. (eg. `address(0)`) */ error OwnableInvalidOwner(address owner); event OwnershipTransferred(address indexed previousOwner, address indexed newOwner); /** * @dev Initializes the contract setting the address provided by the deployer as the initial owner. */ constructor(address initialOwner) { if (initialOwner == address(0)) { revert OwnableInvalidOwner(address(0)); } _transferOwnership(initialOwner); } /** * @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 { if (owner() != _msgSender()) { revert OwnableUnauthorizedAccount(_msgSender()); } } /** * @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 { if (newOwner == address(0)) { revert OwnableInvalidOwner(address(0)); } _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 v5.0.0) (interfaces/draft-IERC6093.sol) pragma solidity ^0.8.20; /** * @dev Standard ERC20 Errors * Interface of the https://eips.ethereum.org/EIPS/eip-6093[ERC-6093] custom errors for ERC20 tokens. */ interface IERC20Errors { /** * @dev Indicates an error related to the current `balance` of a `sender`. Used in transfers. * @param sender Address whose tokens are being transferred. * @param balance Current balance for the interacting account. * @param needed Minimum amount required to perform a transfer. */ error ERC20InsufficientBalance(address sender, uint256 balance, uint256 needed); /** * @dev Indicates a failure with the token `sender`. Used in transfers. * @param sender Address whose tokens are being transferred. */ error ERC20InvalidSender(address sender); /** * @dev Indicates a failure with the token `receiver`. Used in transfers. * @param receiver Address to which tokens are being transferred. */ error ERC20InvalidReceiver(address receiver); /** * @dev Indicates a failure with the `spender`’s `allowance`. Used in transfers. * @param spender Address that may be allowed to operate on tokens without being their owner. * @param allowance Amount of tokens a `spender` is allowed to operate with. * @param needed Minimum amount required to perform a transfer. */ error ERC20InsufficientAllowance(address spender, uint256 allowance, uint256 needed); /** * @dev Indicates a failure with the `approver` of a token to be approved. Used in approvals. * @param approver Address initiating an approval operation. */ error ERC20InvalidApprover(address approver); /** * @dev Indicates a failure with the `spender` to be approved. Used in approvals. * @param spender Address that may be allowed to operate on tokens without being their owner. */ error ERC20InvalidSpender(address spender); } /** * @dev Standard ERC721 Errors * Interface of the https://eips.ethereum.org/EIPS/eip-6093[ERC-6093] custom errors for ERC721 tokens. */ interface IERC721Errors { /** * @dev Indicates that an address can't be an owner. For example, `address(0)` is a forbidden owner in EIP-20. * Used in balance queries. * @param owner Address of the current owner of a token. */ error ERC721InvalidOwner(address owner); /** * @dev Indicates a `tokenId` whose `owner` is the zero address. * @param tokenId Identifier number of a token. */ error ERC721NonexistentToken(uint256 tokenId); /** * @dev Indicates an error related to the ownership over a particular token. Used in transfers. * @param sender Address whose tokens are being transferred. * @param tokenId Identifier number of a token. * @param owner Address of the current owner of a token. */ error ERC721IncorrectOwner(address sender, uint256 tokenId, address owner); /** * @dev Indicates a failure with the token `sender`. Used in transfers. * @param sender Address whose tokens are being transferred. */ error ERC721InvalidSender(address sender); /** * @dev Indicates a failure with the token `receiver`. Used in transfers. * @param receiver Address to which tokens are being transferred. */ error ERC721InvalidReceiver(address receiver); /** * @dev Indicates a failure with the `operator`’s approval. Used in transfers. * @param operator Address that may be allowed to operate on tokens without being their owner. * @param tokenId Identifier number of a token. */ error ERC721InsufficientApproval(address operator, uint256 tokenId); /** * @dev Indicates a failure with the `approver` of a token to be approved. Used in approvals. * @param approver Address initiating an approval operation. */ error ERC721InvalidApprover(address approver); /** * @dev Indicates a failure with the `operator` to be approved. Used in approvals. * @param operator Address that may be allowed to operate on tokens without being their owner. */ error ERC721InvalidOperator(address operator); } /** * @dev Standard ERC1155 Errors * Interface of the https://eips.ethereum.org/EIPS/eip-6093[ERC-6093] custom errors for ERC1155 tokens. */ interface IERC1155Errors { /** * @dev Indicates an error related to the current `balance` of a `sender`. Used in transfers. * @param sender Address whose tokens are being transferred. * @param balance Current balance for the interacting account. * @param needed Minimum amount required to perform a transfer. * @param tokenId Identifier number of a token. */ error ERC1155InsufficientBalance(address sender, uint256 balance, uint256 needed, uint256 tokenId); /** * @dev Indicates a failure with the token `sender`. Used in transfers. * @param sender Address whose tokens are being transferred. */ error ERC1155InvalidSender(address sender); /** * @dev Indicates a failure with the token `receiver`. Used in transfers. * @param receiver Address to which tokens are being transferred. */ error ERC1155InvalidReceiver(address receiver); /** * @dev Indicates a failure with the `operator`’s approval. Used in transfers. * @param operator Address that may be allowed to operate on tokens without being their owner. * @param owner Address of the current owner of a token. */ error ERC1155MissingApprovalForAll(address operator, address owner); /** * @dev Indicates a failure with the `approver` of a token to be approved. Used in approvals. * @param approver Address initiating an approval operation. */ error ERC1155InvalidApprover(address approver); /** * @dev Indicates a failure with the `operator` to be approved. Used in approvals. * @param operator Address that may be allowed to operate on tokens without being their owner. */ error ERC1155InvalidOperator(address operator); /** * @dev Indicates an array length mismatch between ids and values in a safeBatchTransferFrom operation. * Used in batch transfers. * @param idsLength Length of the array of token identifiers * @param valuesLength Length of the array of token amounts */ error ERC1155InvalidArrayLength(uint256 idsLength, uint256 valuesLength); } // SPDX-License-Identifier: MIT // OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/ERC20.sol) pragma solidity ^0.8.20; import {IERC20} from "./IERC20.sol"; import {IERC20Metadata} from "./extensions/IERC20Metadata.sol"; import {Context} from "../../utils/Context.sol"; import {IERC20Errors} from "../../interfaces/draft-IERC6093.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}. * * TIP: For a detailed writeup see our guide * https://forum.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How * to implement supply mechanisms]. * * The default value of {decimals} is 18. To change this, you should override * this function so it returns a different value. * * 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. */ abstract contract ERC20 is Context, IERC20, IERC20Metadata, IERC20Errors { mapping(address account => uint256) private _balances; mapping(address account => mapping(address spender => uint256)) private _allowances; uint256 private _totalSupply; string private _name; string private _symbol; /** * @dev Sets the values for {name} and {symbol}. * * 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 returns (string memory) { return _name; } /** * @dev Returns the symbol of the token, usually a shorter version of the * name. */ function symbol() public view virtual 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 default value returned by this function, unless * it's 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 returns (uint8) { return 18; } /** * @dev See {IERC20-totalSupply}. */ function totalSupply() public view virtual returns (uint256) { return _totalSupply; } /** * @dev See {IERC20-balanceOf}. */ function balanceOf(address account) public view virtual 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 `value`. */ function transfer(address to, uint256 value) public virtual returns (bool) { address owner = _msgSender(); _transfer(owner, to, value); return true; } /** * @dev See {IERC20-allowance}. */ function allowance(address owner, address spender) public view virtual returns (uint256) { return _allowances[owner][spender]; } /** * @dev See {IERC20-approve}. * * NOTE: If `value` 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 value) public virtual returns (bool) { address owner = _msgSender(); _approve(owner, spender, value); 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 `value`. * - the caller must have allowance for ``from``'s tokens of at least * `value`. */ function transferFrom(address from, address to, uint256 value) public virtual returns (bool) { address spender = _msgSender(); _spendAllowance(from, spender, value); _transfer(from, to, value); return true; } /** * @dev Moves a `value` 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. * * NOTE: This function is not virtual, {_update} should be overridden instead. */ function _transfer(address from, address to, uint256 value) internal { if (from == address(0)) { revert ERC20InvalidSender(address(0)); } if (to == address(0)) { revert ERC20InvalidReceiver(address(0)); } _update(from, to, value); } /** * @dev Transfers a `value` amount of tokens from `from` to `to`, or alternatively mints (or burns) if `from` * (or `to`) is the zero address. All customizations to transfers, mints, and burns should be done by overriding * this function. * * Emits a {Transfer} event. */ function _update(address from, address to, uint256 value) internal virtual { if (from == address(0)) { // Overflow check required: The rest of the code assumes that totalSupply never overflows _totalSupply += value; } else { uint256 fromBalance = _balances[from]; if (fromBalance < value) { revert ERC20InsufficientBalance(from, fromBalance, value); } unchecked { // Overflow not possible: value <= fromBalance <= totalSupply. _balances[from] = fromBalance - value; } } if (to == address(0)) { unchecked { // Overflow not possible: value <= totalSupply or value <= fromBalance <= totalSupply. _totalSupply -= value; } } else { unchecked { // Overflow not possible: balance + value is at most totalSupply, which we know fits into a uint256. _balances[to] += value; } } emit Transfer(from, to, value); } /** * @dev Creates a `value` amount of tokens and assigns them to `account`, by transferring it from address(0). * Relies on the `_update` mechanism * * Emits a {Transfer} event with `from` set to the zero address. * * NOTE: This function is not virtual, {_update} should be overridden instead. */ function _mint(address account, uint256 value) internal { if (account == address(0)) { revert ERC20InvalidReceiver(address(0)); } _update(address(0), account, value); } /** * @dev Destroys a `value` amount of tokens from `account`, lowering the total supply. * Relies on the `_update` mechanism. * * Emits a {Transfer} event with `to` set to the zero address. * * NOTE: This function is not virtual, {_update} should be overridden instead */ function _burn(address account, uint256 value) internal { if (account == address(0)) { revert ERC20InvalidSender(address(0)); } _update(account, address(0), value); } /** * @dev Sets `value` 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. * * Overrides to this logic should be done to the variant with an additional `bool emitEvent` argument. */ function _approve(address owner, address spender, uint256 value) internal { _approve(owner, spender, value, true); } /** * @dev Variant of {_approve} with an optional flag to enable or disable the {Approval} event. * * By default (when calling {_approve}) the flag is set to true. On the other hand, approval changes made by * `_spendAllowance` during the `transferFrom` operation set the flag to false. This saves gas by not emitting any * `Approval` event during `transferFrom` operations. * * Anyone who wishes to continue emitting `Approval` events on the`transferFrom` operation can force the flag to * true using the following override: * ``` * function _approve(address owner, address spender, uint256 value, bool) internal virtual override { * super._approve(owner, spender, value, true); * } * ``` * * Requirements are the same as {_approve}. */ function _approve(address owner, address spender, uint256 value, bool emitEvent) internal virtual { if (owner == address(0)) { revert ERC20InvalidApprover(address(0)); } if (spender == address(0)) { revert ERC20InvalidSpender(address(0)); } _allowances[owner][spender] = value; if (emitEvent) { emit Approval(owner, spender, value); } } /** * @dev Updates `owner` s allowance for `spender` based on spent `value`. * * Does not update the allowance value in case of infinite allowance. * Revert if not enough allowance is available. * * Does not emit an {Approval} event. */ function _spendAllowance(address owner, address spender, uint256 value) internal virtual { uint256 currentAllowance = allowance(owner, spender); if (currentAllowance != type(uint256).max) { if (currentAllowance < value) { revert ERC20InsufficientAllowance(spender, currentAllowance, value); } unchecked { _approve(owner, spender, currentAllowance - value, false); } } } } // SPDX-License-Identifier: MIT // OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/IERC20.sol) pragma solidity ^0.8.20; /** * @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 value of tokens in existence. */ function totalSupply() external view returns (uint256); /** * @dev Returns the value of tokens owned by `account`. */ function balanceOf(address account) external view returns (uint256); /** * @dev Moves a `value` amount of 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 value) 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 a `value` amount of tokens 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 value) external returns (bool); /** * @dev Moves a `value` amount of tokens from `from` to `to` using the * allowance mechanism. `value` 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 value) external returns (bool); } // SPDX-License-Identifier: MIT // OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/extensions/IERC20Metadata.sol) pragma solidity ^0.8.20; import {IERC20} from "../IERC20.sol"; /** * @dev Interface for the optional metadata functions from the ERC20 standard. */ 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 v5.0.1) (utils/Context.sol) pragma solidity ^0.8.20; /** * @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; } }