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看了uniswap v2 很多遍,对于其中代码的熟悉程度在慢慢提高,因此做了些笔记来记录其中的要点:
factory合约的作用:
创建代币对createPair:
通过使用salt方式,通过create2方法对生成代币对地址,同时还初始化了代币对合约。
对代币对进行排序:
(address token0, address token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
这样做的好处:
1、保证交易对的一致性,并避免某些错误(例如:同一对代币不同的排序会导致流动性池地址不同,进而导致交易失败或价格错误)。
2、防止潜在攻击,比如:重入攻击
3、流动性池子管理,可能会影响交易价格和滑点
4、价格计算,避免不必要的价格波动
pragma solidity =0.5.16;
import './interfaces/IUniswapV2Factory.sol';
import './UniswapV2Pair.sol';
contract UniswapV2Factory is IUniswapV2Factory {
address public feeTo;
address public feeToSetter;
mapping(address => mapping(address => address)) public getPair;
address[] public allPairs;
event PairCreated(address indexed token0, address indexed token1, address pair, uint);
constructor(address _feeToSetter) public {
feeToSetter = _feeToSetter;
}
function allPairsLength() external view returns (uint) {
return allPairs.length;
}
function createPair(address tokenA, address tokenB) external returns (address pair) {
require(tokenA != tokenB, 'UniswapV2: IDENTICAL_ADDRESSES');
(address token0, address token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
require(token0 != address(0), 'UniswapV2: ZERO_ADDRESS');
require(getPair[token0][token1] == address(0), 'UniswapV2: PAIR_EXISTS'); // single check is sufficient
bytes memory bytecode = type(UniswapV2Pair).creationCode;
bytes32 salt = keccak256(abi.encodePacked(token0, token1));
assembly {
pair := create2(0, add(bytecode, 32), mload(bytecode), salt)
}
IUniswapV2Pair(pair).initialize(token0, token1);
getPair[token0][token1] = pair;
getPair[token1][token0] = pair; // populate mapping in the reverse direction
allPairs.push(pair);
emit PairCreated(token0, token1, pair, allPairs.length);
}
function setFeeTo(address _feeTo) external {
require(msg.sender == feeToSetter, 'UniswapV2: FORBIDDEN');
feeTo = _feeTo;
}
function setFeeToSetter(address _feeToSetter) external {
require(msg.sender == feeToSetter, 'UniswapV2: FORBIDDEN');
feeToSetter = _feeToSetter;
}
}
看了uniswap v2 很多遍,对于其中代码的熟悉程度在慢慢提高,因此做了些笔记来记录其中的要点:
factory合约的作用:
创建代币对createPair:
通过使用salt方式,通过create2方法对生成代币对地址,同时还初始化了代币对合约。
对代币对进行排序:
(address token0, address token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
这样做的好处:
1、保证交易对的一致性,并避免某些错误(例如:同一对代币不同的排序会导致流动性池地址不同,进而导致交易失败或价格错误)。
2、防止潜在攻击,比如:重入攻击
3、流动性池子管理,可能会影响交易价格和滑点
4、价格计算,避免不必要的价格波动
pragma solidity =0.5.16;
import './interfaces/IUniswapV2Factory.sol';
import './UniswapV2Pair.sol';
contract UniswapV2Factory is IUniswapV2Factory {
address public feeTo;
address public feeToSetter;
mapping(address => mapping(address => address)) public getPair;
address[] public allPairs;
event PairCreated(address indexed token0, address indexed token1, address pair, uint);
constructor(address _feeToSetter) public {
feeToSetter = _feeToSetter;
}
function allPairsLength() external view returns (uint) {
return allPairs.length;
}
function createPair(address tokenA, address tokenB) external returns (address pair) {
require(tokenA != tokenB, 'UniswapV2: IDENTICAL_ADDRESSES');
(address token0, address token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
require(token0 != address(0), 'UniswapV2: ZERO_ADDRESS');
require(getPair[token0][token1] == address(0), 'UniswapV2: PAIR_EXISTS'); // single check is sufficient
bytes memory bytecode = type(UniswapV2Pair).creationCode;
bytes32 salt = keccak256(abi.encodePacked(token0, token1));
assembly {
pair := create2(0, add(bytecode, 32), mload(bytecode), salt)
}
IUniswapV2Pair(pair).initialize(token0, token1);
getPair[token0][token1] = pair;
getPair[token1][token0] = pair; // populate mapping in the reverse direction
allPairs.push(pair);
emit PairCreated(token0, token1, pair, allPairs.length);
}
function setFeeTo(address _feeTo) external {
require(msg.sender == feeToSetter, 'UniswapV2: FORBIDDEN');
feeTo = _feeTo;
}
function setFeeToSetter(address _feeToSetter) external {
require(msg.sender == feeToSetter, 'UniswapV2: FORBIDDEN');
feeToSetter = _feeToSetter;
}
}
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