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| 1 | +// SPDX-License-Identifier: MIT |
| 2 | +pragma solidity ^0.8.28; |
| 3 | + |
| 4 | +/** |
| 5 | + * @title Minimal ERC20 Token |
| 6 | + * @dev Implements the basic ERC20 interface. |
| 7 | + */ |
| 8 | +contract MyToken { |
| 9 | + // Token details |
| 10 | + string public name = "MyToken"; |
| 11 | + string public symbol = "MTK"; |
| 12 | + uint8 public decimals = 18; |
| 13 | + |
| 14 | + // Tracks the total token supply |
| 15 | + uint256 public totalSupply; |
| 16 | + |
| 17 | + // Owner of the token contract (for minting, etc., if desired) |
| 18 | + address public owner; |
| 19 | + |
| 20 | + // Balances for each account |
| 21 | + mapping(address => uint256) private _balances; |
| 22 | + |
| 23 | + // Allowances for each account, where allowances[from][spender] = amount |
| 24 | + mapping(address => mapping(address => uint256)) private _allowances; |
| 25 | + |
| 26 | + // Events |
| 27 | + event Transfer(address indexed from, address indexed to, uint256 value); |
| 28 | + event Approval(address indexed owner, address indexed spender, uint256 value); |
| 29 | + |
| 30 | + // Constructor: Mint an initial supply to the deployer |
| 31 | + constructor(uint256 initialSupply) { |
| 32 | + owner = msg.sender; |
| 33 | + _mint(owner, initialSupply); |
| 34 | + } |
| 35 | + |
| 36 | + /** |
| 37 | + * @dev Returns the balance of a given account. |
| 38 | + */ |
| 39 | + function balanceOf(address account) external view returns (uint256) { |
| 40 | + return _balances[account]; |
| 41 | + } |
| 42 | + |
| 43 | + /** |
| 44 | + * @dev Moves `amount` tokens from caller's account to `recipient`. |
| 45 | + * |
| 46 | + * Emits a {Transfer} event. |
| 47 | + */ |
| 48 | + function transfer(address recipient, uint256 amount) external returns (bool) { |
| 49 | + _transfer(msg.sender, recipient, amount); |
| 50 | + return true; |
| 51 | + } |
| 52 | + |
| 53 | + /** |
| 54 | + * @dev Returns the remaining number of tokens that `spender` is allowed |
| 55 | + * to spend on behalf of `owner` through `transferFrom`. |
| 56 | + */ |
| 57 | + function allowance(address _owner, address _spender) external view returns (uint256) { |
| 58 | + return _allowances[_owner][_spender]; |
| 59 | + } |
| 60 | + |
| 61 | + /** |
| 62 | + * @dev Sets `amount` as the allowance of `spender` over the caller's tokens. |
| 63 | + * |
| 64 | + * Emits an {Approval} event. |
| 65 | + */ |
| 66 | + function approve(address spender, uint256 amount) external returns (bool) { |
| 67 | + _approve(msg.sender, spender, amount); |
| 68 | + return true; |
| 69 | + } |
| 70 | + |
| 71 | + /** |
| 72 | + * @dev Moves `amount` tokens from `sender` to `recipient` using the |
| 73 | + * allowance mechanism. `amount` is then deducted from the caller's allowance. |
| 74 | + * |
| 75 | + * Emits a {Transfer} event. |
| 76 | + */ |
| 77 | + function transferFrom( |
| 78 | + address sender, |
| 79 | + address recipient, |
| 80 | + uint256 amount |
| 81 | + ) external returns (bool) { |
| 82 | + uint256 currentAllowance = _allowances[sender][msg.sender]; |
| 83 | + require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance"); |
| 84 | + |
| 85 | + _approve(sender, msg.sender, currentAllowance - amount); |
| 86 | + _transfer(sender, recipient, amount); |
| 87 | + |
| 88 | + return true; |
| 89 | + } |
| 90 | + |
| 91 | + /** |
| 92 | + * @dev Creates new tokens and assigns them to `account`, increasing the total supply. |
| 93 | + * |
| 94 | + * Emits a {Transfer} event. |
| 95 | + * |
| 96 | + * WARNING: This function is public. In production, consider restricting access (e.g. onlyOwner). |
| 97 | + */ |
| 98 | + function mint(address account, uint256 amount) public { |
| 99 | + require(msg.sender == owner, "ERC20: only owner can mint"); |
| 100 | + _mint(account, amount); |
| 101 | + } |
| 102 | + |
| 103 | + // --------------------- |
| 104 | + // Internal / Private |
| 105 | + // --------------------- |
| 106 | + |
| 107 | + /** |
| 108 | + * @dev Internal function that moves `amount` tokens from `sender` to `recipient`. |
| 109 | + */ |
| 110 | + function _transfer(address sender, address recipient, uint256 amount) internal { |
| 111 | + require(sender != address(0), "ERC20: transfer from the zero address"); |
| 112 | + require(recipient != address(0), "ERC20: transfer to the zero address"); |
| 113 | + require(_balances[sender] >= amount, "ERC20: transfer amount exceeds balance"); |
| 114 | + |
| 115 | + _balances[sender] -= amount; |
| 116 | + _balances[recipient] += amount; |
| 117 | + |
| 118 | + emit Transfer(sender, recipient, amount); |
| 119 | + } |
| 120 | + |
| 121 | + /** |
| 122 | + * @dev Internal function that sets `amount` as the allowance of `spender` over the `owner` s tokens. |
| 123 | + */ |
| 124 | + function _approve( |
| 125 | + address tokenOwner, |
| 126 | + address spender, |
| 127 | + uint256 amount |
| 128 | + ) internal { |
| 129 | + require(tokenOwner != address(0), "ERC20: approve from the zero address"); |
| 130 | + require(spender != address(0), "ERC20: approve to the zero address"); |
| 131 | + |
| 132 | + _allowances[tokenOwner][spender] = amount; |
| 133 | + emit Approval(tokenOwner, spender, amount); |
| 134 | + } |
| 135 | + |
| 136 | + /** |
| 137 | + * @dev Internal function to create `amount` tokens and assign them to `account`. |
| 138 | + */ |
| 139 | + function _mint(address account, uint256 amount) internal { |
| 140 | + require(account != address(0), "ERC20: mint to the zero address"); |
| 141 | + |
| 142 | + totalSupply += amount; |
| 143 | + _balances[account] += amount; |
| 144 | + emit Transfer(address(0), account, amount); |
| 145 | + } |
| 146 | +} |
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