第100篇 兼容 ETH 与 ERC20 的库合约

本文仅记录一种兼容 ETH 与 ERC20 资产的库合约；

1. 库合约源码（0.6.12）

本合约来自网络；

pragma solidity ^0.6.12;

import "../utils/math/SafeMath.sol";
import "../token/ERC20/IERC20.sol";
import "../token/ERC20/utils/SafeERC20.sol";

library UniversalERC20 {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    IERC20 private constant ZERO_ADDRESS =
        IERC20(0x0000000000000000000000000000000000000000);
    IERC20 private constant ETH_ADDRESS =
        IERC20(0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE);

    function universalTransfer(
        IERC20 token,
        address to,
        uint256 amount
    ) internal returns (bool) {
        if (amount == 0) {
            return false;
        }

        if (isETH(token)) {
            address(uint160(to)).transfer(amount);
        } else {
            token.safeTransfer(to, amount);
        }
        return true;
    }

    function universalTrans