# 理想区块链-DEX代码

By [xin](https://paragraph.com/@xinchain) · 2022-07-05

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    // SPDX-License-Identifier: GPL-3.0
    
    pragma solidity 0.8.10;
    
    library safeMath {
        function sub(uint256 a, uint256 b) internal pure returns (uint256) {
            assert(b <= a);
            return a - b;
        }
    
        function add(uint256 a, uint256 b) internal pure returns (uint256) {
            uint256 c = a + b;
            assert(c >= a);
            return c;
        }
    }
    
    interface IERC20 {
        // 获取合约地址
        function getAddress() external view returns (address);
        // 获取代币发行总量
        function totalSupply() external view returns (uint256);
        // 根据地址获取代币的余额
        function balanceOf(address account) external view returns (uint256);
        // 代理可转移的代币数量
        function allowance(address owner, address supender) external view returns (uint256);
    
        // 转账
        function transfer(address recipient, uint256 amount) external returns (bool);
        // 设置代理能转账的金额
        function approve(address owner, address spender, uint256 amount) external returns (bool);
        // 转账
        function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    
        event Transfer(address indexed from, address indexed to, uint256 value);
        event Approval(address indexed owner, address indexed spender, uint256 value);
    }
    
    // 代币实现
    contract ERC20Basic is IERC20 {
        string public constant name = "ERC-xinChain"; // 代币名称
        string public constant symbol = "ERC-xin"; // 代币简称
        uint8 public constant decimals = 18;
    
        mapping(address => uint256) balances; // 地址对应的余额数量
        mapping(address => mapping(address => uint256)) allowedBalence; // 代理商能处理的代币数量
    
        uint256 totalSupply_ = 10 ether; // 发行数量，ether指的是单位，类似吨，也可以使用8个0
    
        using safeMath for uint256;
    
        constructor () {
            balances[msg.sender] = totalSupply_; // 将代币分发给创建者
        } 
    
         // 获取合约地址
        function getAddress() external view returns (address){
            return address(this); // 当前合约的地址
        }
        // 获取代币发行总量
        function totalSupply() external view returns (uint256){
            return totalSupply_;
        }
    
        // 根据地址获取代币的余额
        function balanceOf(address tokenOwner) public override view returns (uint256){
            return balances[tokenOwner]; // 根据地址获取余额
        }
    
        // 转账
        function transfer(address receiver, uint256 amount) public override returns (bool){
            require(amount <= balances[msg.sender]);
            balances[msg.sender] = balances[msg.sender].sub(amount);
            balances[receiver] = balances[receiver].add(amount);
            emit Transfer(msg.sender, receiver, amount);
            return true;
        }
    
        // 设置代理能转账的金额
        function approve(address owner, address delegate, uint256 amount) external returns (bool){
            allowedBalence[owner][delegate] = amount;
            emit Approval(owner, delegate, amount);
            return true;
        }
    
        // 代理可转移的代币数量
        function allowance(address owner, address delegate) external view returns (uint256){
            return allowedBalence[owner][delegate];
        }
    
        // 转账
        function transferFrom(address owner, address buyer, uint256 amount) external returns (bool){
            require(amount <= balances[owner]);
            require(amount <= allowedBalence[owner][msg.sender]);
    
            balances[owner] = balances[owner].sub(amount);
            allowedBalence[owner][buyer] = allowedBalence[owner][buyer].sub(amount);
            balances[buyer] = balances[buyer].add(amount);
            emit Transfer(owner, buyer, amount);
            return true;
        }
    }
    
    
    contract DEX {
        event Bought(uint256 amount);
        event Sold(uint256 amount);
         
        IERC20 public token;
    
        constructor () {
            token = new ERC20Basic();
        }
    
        // 买入
        function buy() payable public {
            uint256 amountTobuy = msg.value; //传入以太坊
            uint256 dexBalance = token.balanceOf(address(this)); //此合约中自己创建代币的数量
            require(amountTobuy > 0 , "You need to send some Ethoer"); // amountTobuy 必须传入以太，使用以太购买此代币
            require(amountTobuy <= dexBalance, "Not enough tokens in the reserve"); // 合约中代币的数量要大于要购买的量
            token.transfer(msg.sender, amountTobuy);
            emit Bought(amountTobuy);
        }
    
        function sell(uint256 amount) public {
            require(amount > 0, "You need to sell at least some tokens."); // 卖出数量要大于0
            uint256 allowance = token.allowance(msg.sender, address(this));
            require(allowance >= amount, "check the token allowance");
            token.transferFrom(msg.sender, address(this), amount);
    
            emit Sold(amount);
        }
    
        function getDexBalance() public view returns(uint256) {
            return token.balanceOf(address(this));
        }
    
        function getOwnerBalance() public view returns(uint256) {
            return token.balanceOf(msg.sender);
        }
    
        function getAddress() public view returns (address) {
            return address(this);
        }
    
        function getTokenAddress() public view returns (address) {
            return token.getAddress();
        }
    
        function getTotalSupply() public view returns (uint256) {
            return token.totalSupply();
        }
    
        function getSenderAddress() public view returns (address) {
            return address(msg.sender);
        }
    
        function getAllowance() public view returns (uint256) {
            uint256 allowance = token.allowance(msg.sender, address(this));
            return allowance;
        }
    
        // 授权当前合约转移代币数量
        function approve(uint256 amount) public returns(bool) {
            bool isApprove = token.approve(msg.sender, address(this), amount);
            return isApprove;
        }
    }

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*Originally published on [xin](https://paragraph.com/@xinchain/dex)*