update

contracts/external/ERC20/InitializableFragERC20.sol

@@ -0,0 +1,92 @@
+/*
+
+    Copyright 2020 DODO ZOO.
+    SPDX-License-Identifier: Apache-2.0
+
+*/
+
+pragma solidity 0.6.9;
+
+import {SafeMath} from "../../lib/SafeMath.sol";
+
+contract InitializableFragERC20 {
+    using SafeMath for uint256;
+
+    string public name;
+    string public symbol;
+    uint256 public totalSupply;
+
+    bool public initialized;
+
+    mapping(address => uint256) internal balances;
+    mapping(address => mapping(address => uint256)) internal allowed;
+
+    event Transfer(address indexed from, address indexed to, uint256 amount);
+    event Approval(address indexed owner, address indexed spender, uint256 amount);
+
+    function init(
+        address _creator,
+        uint256 _totalSupply,
+        string memory _name,
+        string memory _symbol
+    ) public {
+        require(!initialized, "TOKEN_INITIALIZED");
+        initialized = true;
+        totalSupply = _totalSupply;
+        balances[_creator] = _totalSupply;
+        name = _name;
+        symbol = _symbol;
+        emit Transfer(address(0), _creator, _totalSupply);
+    }
+
+    function decimals() public view returns (uint8) {
+        return 18;
+    }
+
+    function transfer(address to, uint256 amount) public returns (bool) {
+        _transfer(msg.sender, to, amount);
+        return true;
+    }
+
+    function balanceOf(address owner) public view returns (uint256 balance) {
+        return balances[owner];
+    }
+
+    function transferFrom(
+        address from,
+        address to,
+        uint256 amount
+    ) public returns (bool) {
+        require(to != address(0), "TO_ADDRESS_IS_EMPTY");
+        require(amount <= balances[from], "BALANCE_NOT_ENOUGH");
+        require(amount <= allowed[from][msg.sender], "ALLOWANCE_NOT_ENOUGH");
+
+        balances[from] = balances[from].sub(amount);
+        balances[to] = balances[to].add(amount);
+        allowed[from][msg.sender] = allowed[from][msg.sender].sub(amount);
+        emit Transfer(from, to, amount);
+        return true;
+    }
+
+    function approve(address spender, uint256 amount) public returns (bool) {
+        allowed[msg.sender][spender] = amount;
+        emit Approval(msg.sender, spender, amount);
+        return true;
+    }
+
+    function allowance(address owner, address spender) public view returns (uint256) {
+        return allowed[owner][spender];
+    }
+
+    function _transfer(address sender, address recipient, uint256 amount) internal {
+        require(sender != address(0), "FROM_ADDRESS_IS_EMPTY");
+        require(recipient != address(0), "TO_ADDRESS_IS_EMPTY");
+        require(amount <= balances[sender], "BALANCE_NOT_ENOUGH");
+
+        balances[sender] = balances[sender].sub(amount);
+        balances[recipient] = balances[recipient].add(amount);
+
+        emit Transfer(sender, recipient, amount);
+    }
+
+}