add erc20

src/contracts/erc20.sol

@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.25;
+
+interface IERC20 {
+    function totalSupply() external view returns (uint256);
+    function balanceOf(address account) external view returns (uint256);
+    function transfer(address recipient, uint256 amount) external returns (bool);
+    function allowance(address owner, address spender) external view returns (uint256);
+    function approve(address spender, uint256 amount) external returns (bool);
+    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
+}
+
+contract ERC20 is IERC20 {
+    event Transfer(address indexed from, address indexed to, uint256 value);
+    event Approval(address indexed owner, address indexed spender, uint256 value);
+
+    uint256 public totalSupply;
+    mapping(address => uint256) public balanceOf;
+    mapping(address => mapping(address => uint256)) public allowance;
+    string public name;
+    string public symbol;
+    uint8 public decimals;
+
+    constructor(string memory _name, string memory _symbol, uint8 _decimals) {
+        name = _name;
+        symbol = _symbol;
+        decimals = _decimals;
+    }
+
+    function transfer(address recipient, uint256 amount) external returns (bool) {
+        balanceOf[msg.sender] -= amount;
+        balanceOf[recipient] += amount;
+        emit Transfer(msg.sender, recipient, amount);
+        return true;
+    }
+
+    function approve(address spender, uint256 amount) external returns (bool) {
+        allowance[msg.sender][spender] = amount;
+        emit Approval(msg.sender, spender, amount);
+        return true;
+    }
+
+    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool) {
+        allowance[sender][msg.sender] -= amount;
+        balanceOf[sender] -= amount;
+        balanceOf[recipient] += amount;
+        emit Transfer(sender, recipient, amount);
+        return true;
+    }
+
+    function _mint(address to, uint256 amount) internal {
+        balanceOf[to] += amount;
+        totalSupply += amount;
+        emit Transfer(address(0), to, amount);
+    }
+
+    function _burn(address from, uint256 amount) internal {
+        balanceOf[from] -= amount;
+        totalSupply -= amount;
+        emit Transfer(from, address(0), amount);
+    }
+
+    function mint(address to, uint256 amount) external {
+        _mint(to, amount);
+    }
+
+    function burn(address from, uint256 amount) external {
+        _burn(from, amount);
+    }
+}