ERC20.sol

// SPDX-License-Identifier: MIT
// WTF Solidity by 0xAA

pragma solidity ^0.8.21;

import "./IERC20.sol";

contract ERC20 is IERC20 {

    mapping(address => uint256) public override balanceOf;

    mapping(address => mapping(address => uint256)) public override allowance;

    uint256 public override totalSupply;   // 代币总供给

    string public name;   // 名称
    string public symbol;  // 符号
    
    uint8 public decimals = 18; // 小数位数

    // @dev 在合约部署的时候实现合约名称和符号
    constructor(string memory name_, string memory symbol_){
        name = name_;
        symbol = symbol_;
    }

    // @dev 实现`transfer`函数，代币转账逻辑
    function transfer(address recipient, uint amount) public override returns (bool) {
        balanceOf[msg.sender] -= amount;
        balanceOf[recipient] += amount;
        emit Transfer(msg.sender, recipient, amount);
        return true;
    }

    // @dev 实现 `approve` 函数, 代币授权逻辑
    function approve(address spender, uint amount) public override returns (bool) {
        allowance[msg.sender][spender] = amount;
        emit Approval(msg.sender, spender, amount);
        return true;
    }

    // @dev 实现`transferFrom`函数，代币授权转账逻辑
    function transferFrom(
        address sender,
        address recipient,
        uint amount
    ) public override returns (bool) {
        allowance[sender][msg.sender] -= amount;
        balanceOf[sender] -= amount;
        balanceOf[recipient] += amount;
        emit Transfer(sender, recipient, amount);
        return true;
    }

    // @dev 铸造代币，从 `0` 地址转账给 调用者地址
    function mint(uint amount) external {
        balanceOf[msg.sender] += amount;
        totalSupply += amount;
        emit Transfer(address(0), msg.sender, amount);
    }

    // @dev 销毁代币，从 调用者地址 转账给  `0` 地址
    function burn(uint amount) external {
        balanceOf[msg.sender] -= amount;
        totalSupply -= amount;
        emit Transfer(msg.sender, address(0), amount);
    }

}