3分钟Solidity: 15.17 DeFi - 金库

欢迎订阅专栏：3分钟Solidity--智能合约--Web3区块链技术必学

金库

如需获取此内容的最新版本，请参阅Cyfrin.io上的金库（代码示例）。

这是一个简单的金库合约示例，通常用于DeFi协议中。

主网上的大多数金库合约更为复杂。在此我们将重点介绍计算存入铸币份额及提取代币数量的数学逻辑。

合约运作方式

1. 用户存入资金时，会铸造一定数量的份额。
2. DeFi协议将利用用户的存款以某种方式产生收益。
3. 用户销毁份额以提取其代币及收益。

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.26;

contract Vault {
    IERC20 public immutable token;

    uint256 public totalSupply;
    mapping(address => uint256) public balanceOf;

    constructor(address _token) {
        token = IERC20(_token);
    }

    function _mint(address _to, uint256 _shares) private {
        totalSupply += _shares;
        balanceOf[_to] += _shares;
    }

    function _burn(address _from, uint256 _shares) private {
        totalSupply -= _shares;
        balanceOf[_from] -= _shares;
    }

    function deposit(uint256 _amount) external {
        /*
        a = amount
        B = balance of token before deposit
        T = total supply
        s = shares to mint

        (T + s) / T = (a + B) / B 

        s = aT / B
        */
        uint256 shares;
        if (totalSupply == 0) {
            shares = _amount;
        } else {
            shares = (_amount * totalSupply) / token.balanceOf(address(this));
        }

        _mint(msg.sender, shares);
        token.transferFrom(msg.sender, address(this), _amount);
    }

    function withdraw(uint256 _shares) external {
        /*
        a = amount
        B = balance of token before withdraw
        T = total supply
        s = shares to burn

        (T - s) / T = (B - a) / B 

        a = sB / T
        */
        uint256 amount =
            (_shares * token.balanceOf(address(this))) / totalSupply;
        _burn(msg.sender, _shares);
        token.transfer(msg.sender, amount);
    }
}

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);

    event Transfer(address indexed from, address indexed to, uint256 amount);
    event Approval(
        address indexed owner, address indexed spender, uint256 amount
    );
}

Try on Remix

• Vault.sol