# uniswap工厂合约代码详解

**Published by:** [Cognitive](https://paragraph.com/@cognitive/)
**Published on:** 2022-11-19
**URL:** https://paragraph.com/@cognitive/uniswap

## Content

准备练习一下uniswap的合约，今天先开始第一讲，uniswap的工厂合约的代码详解。 推荐视频： 工厂合约代码：`// SPDX-License-Identifier: MIT pragma solidity =0.8.17; import './interfaces/IUniswapV2Factory.sol'; import './UniswapV2Pair.sol'; contract UniswapV2Factory is IUniswapV2Factory { address public feeTo; //收税地址 address public feeToSetter; //收税权限控制地址 //配对映射，地址->(地址->地址) mapping(address => mapping(address => address)) public getPair; //所有配对的数组 address[] public allPairs; //event 配对被创建 event PairCreated(address indexed token0, address indexed token1, address pair, uint256);//构造函数-定义收税权限地址 constructor(address _feeToSetter) public { feeToSetter = _feeToSetter; } //查询配对数组长度 function allPairsLength() external view returns (uint256) { return allPairs.length; } //创建配对合约，返回配对地址pair function createPair(address tokenA, address tokenB) external returns (address pair) { //确定tokenA不等于tokenB require(tokenA != tokenB, 'UniswapV2: IDENTICAL_ADDRESSES'); //三目运算，如果A<B那么A在前B再后，否则相反，然后赋值为0和1 (address token0, address token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA); //确定0不等于0地址，那么1也自然不需要判断 require(token0 != address(0), 'UniswapV2: ZERO_ADDRESS'); //确定配对映射中不存在0和1的交易对。 require(getPair[token0][token1] == address(0), 'UniswapV2: PAIR_EXISTS'); // single check is sufficient //type(合约名).creationCode可以获得合约编译后的bytecode bytes memory bytecode = type(UniswapV2Pair).creationCode; //将0和1打包好通过keccak256创建哈希 bytes32 salt = keccak256(abi.encodePacked(token0, token1)); //内联汇编 //通过create2方法部署合约，返回地址给pair变量 //mload(获取bytecode的长度) assembly { pair := create2(0, add(bytecode, 32), mload(bytecode), salt) } //对pair合约进行初始化操作 IUniswapV2Pair(pair).initialize(token0, token1); //配对映射设置0>=1=pair getPair[token0][token1] = pair; //配对映射设置1>=0=pair getPair[token1][token0] = pair; // populate mapping in the reverse direction //pair地址加入allPairs数组中 allPairs.push(pair); //触发配对成功事件 emit PairCreated(token0, token1, pair, allPairs.length); } //设置收税地址 function setFeeTo(address _feeTo) external { require(msg.sender == feeToSetter, 'UniswapV2: FORBIDDEN'); feeTo = _feeTo; } //设置收税权限控制地址 function setFeeToSetter(address _feeToSetter) external { require(msg.sender == feeToSetter, 'UniswapV2: FORBIDDEN'); feeToSetter = _feeToSetter; }`

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