uniswap v2 代码解读注释

文章目录

注意事项
UniswapV2Factory
UniswapV2Router02
uniswap 闪电贷(待补充)
uniswap 添加/移除lp时手续费公式(待补充)

注意事项

部分说明

首次添加和二次添加lp算法有点差别
查找pair和创建pair，使用了create2，有需要可以具体了解
uniswap v2都是两个erc20组合成一个交易对，跟eth相关的内部都是使用的weth交易
交易方法中都是in/out，相对于pair, 方法中swapExactTokensForTokens，for的两侧带有Exact的，表示该侧的数是固定的精确数，另一边的数量是需要看实际成交时交易池情况，所以也就有了amountOutMin,amountInMax
带supportingFeeOnTransfer的方法是支持转账扣手续费的token
_swap 和_swapSupportingFeeOnTransferTokens的差别是前者是输入参数的数计算得来的amounts, 后者是以交易对实际得到的数去计算
交易和校验K值的算法都是简化后的，可以查看公式推导理解

UniswapV2Factory

/***Submitted for verification at Etherscan.io on 2020-06-05https://etherscan.io/address/0x7a250d5630b4cf539739df2c5dacb4c659f2488d#contracts
*/pragma solidity =0.6.6;interface IUniswapV2Factory {event PairCreated(address indexed token0, address indexed token1, address pair, uint);function feeTo() external view returns (address);function feeToSetter() external view returns (address);function getPair(address tokenA, address tokenB) external view returns (address pair);function allPairs(uint) external view returns (address pair);function allPairsLength() external view returns (uint);function createPair(address tokenA, address tokenB) external returns (address pair);function setFeeTo(address) external;function setFeeToSetter(address) external;
}interface IUniswapV2Pair {event Approval(address indexed owner, address indexed spender, uint value);event Transfer(address indexed from, address indexed to, uint value);function name() external pure returns (string memory);function symbol() external pure returns (string memory);function decimals() external pure returns (uint8);function totalSupply() external view returns (uint);function balanceOf(address owner) external view returns (uint);function allowance(address owner, address spender) external view returns (uint);function approve(address spender, uint value) external returns (bool);function transfer(address to, uint value) external returns (bool);function transferFrom(address from, address to, uint value) external returns (bool);function DOMAIN_SEPARATOR() external view returns (bytes32);function PERMIT_TYPEHASH() external pure returns (bytes32);function nonces(address owner) external view returns (uint);function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;event Mint(address indexed sender, uint amount0, uint amount1);event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);event Swap(address indexed sender,uint amount0In,uint amount1In,uint amount0Out,uint amount1Out,address indexed to);event Sync(uint112 reserve0, uint112 reserve1);function MINIMUM_LIQUIDITY() external pure returns (uint);function factory() external view returns (address);function token0() external view returns (address);function token1() external view returns (address);function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);function price0CumulativeLast() external view returns (uint);function price1CumulativeLast() external view returns (uint);function kLast() external view returns (uint);function mint(address to) external returns (uint liquidity);function burn(address to) external returns (uint amount0, uint amount1);function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;function skim(address to) external;function sync() external;function initialize(address, address) external;
}interface IUniswapV2Router01 {function factory() external pure returns (address);function WETH() external pure returns (address);function addLiquidity(address tokenA,address tokenB,uint amountADesired,uint amountBDesired,uint amountAMin,uint amountBMin,address to,uint deadline) external returns (uint amountA, uint amountB, uint liquidity);function addLiquidityETH(address token,uint amountTokenDesired,uint amountTokenMin,uint amountETHMin,address to,uint deadline) external payable returns (uint amountToken, uint amountETH, uint liquidity);function removeLiquidity(address tokenA,address tokenB,uint liquidity,uint amountAMin,uint amountBMin,address to,uint deadline) external returns (uint amountA, uint amountB);function removeLiquidityETH(address token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline) external returns (uint amountToken, uint amountETH);function removeLiquidityWithPermit(address tokenA,address tokenB,uint liquidity,uint amountAMin,uint amountBMin,address to,uint deadline,bool approveMax, uint8 v, bytes32 r, bytes32 s) external returns (uint amountA, uint amountB);function removeLiquidityETHWithPermit(address token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline,bool approveMax, uint8 v, bytes32 r, bytes32 s) external returns (uint amountToken, uint amountETH);function swapExactTokensForTokens(uint amountIn,uint amountOutMin,address[] calldata path,address to,uint deadline) external returns (uint[] memory amounts);function swapTokensForExactTokens(uint amountOut,uint amountInMax,address[] calldata path,address to,uint deadline) external returns (uint[] memory amounts);function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)externalpayablereturns (uint[] memory amounts);function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)externalreturns (uint[] memory amounts);function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)externalreturns (uint[] memory amounts);function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)externalpayablereturns (uint[] memory amounts);function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}interface IUniswapV2Router02 is IUniswapV2Router01 {function removeLiquidityETHSupportingFeeOnTransferTokens(address token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline) external returns (uint amountETH);function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(address token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline,bool approveMax, uint8 v, bytes32 r, bytes32 s) external returns (uint amountETH);function swapExactTokensForTokensSupportingFeeOnTransferTokens(uint amountIn,uint amountOutMin,address[] calldata path,address to,uint deadline) external;function swapExactETHForTokensSupportingFeeOnTransferTokens(uint amountOutMin,address[] calldata path,address to,uint deadline) external payable;function swapExactTokensForETHSupportingFeeOnTransferTokens(uint amountIn,uint amountOutMin,address[] calldata path,address to,uint deadline) external;
}interface IERC20 {event Approval(address indexed owner, address indexed spender, uint value);event Transfer(address indexed from, address indexed to, uint value);function name() external view returns (string memory);function symbol() external view returns (string memory);function decimals() external view returns (uint8);function totalSupply() external view returns (uint);function balanceOf(address owner) external view returns (uint);function allowance(address owner, address spender) external view returns (uint);function approve(address spender, uint value) external returns (bool);function transfer(address to, uint value) external returns (bool);function transferFrom(address from, address to, uint value) external returns (bool);
}interface IWETH {function deposit() external payable;function transfer(address to, uint value) external returns (bool);function withdraw(uint) external;
}contract UniswapV2Router02 is IUniswapV2Router02 {using SafeMath for uint;address public  immutable override factory;address public  immutable override WETH;//交易时间是否过期，dapp中默认设置时20分钟内成交有效modifier ensure(uint deadline) {require(deadline >= block.timestamp, 'UniswapV2Router: EXPIRED');_;}constructor(address _factory, address _WETH) public {factory = _factory;WETH = _WETH;}receive() external payable {assert(msg.sender == WETH); // only accept ETH via fallback from the WETH contract}// **** ADD LIQUIDITY ****//添加流动性内部方法，通过该方法计算出两个币的实际所需数量function _addLiquidity(address tokenA,//代币地址Aaddress tokenB,//代币地址Buint amountADesired,//代币A 期望添加量uint amountBDesired,//代币B 期望添加量uint amountAMin,//代币A 最小添加量(这两个min,收益添加的时候可以和Desired一样， 二次添加的时候，一般都是小于Desired，具体小多少，算法可以查看uniswap前端代码)uint amountBMin//代币B 最小添加量) internal virtual returns (uint amountA, uint amountB) {//返回值是两个// create the pair if it doesn't exist yet//通过factory,查询pair,如果等于0地址，就表示还没有该交易对，调用创建方法if (IUniswapV2Factory(factory).getPair(tokenA, tokenB) == address(0)) {IUniswapV2Factory(factory).createPair(tokenA, tokenB);//创建交易对}//可以先了解下UniswapV2Library 中相关方法的意思//如果查询两个值都是0，首次添加，直接使用期望值(uint reserveA, uint reserveB) = UniswapV2Library.getReserves(factory, tokenA, tokenB);if (reserveA == 0 && reserveB == 0) {(amountA, amountB) = (amountADesired, amountBDesired);//直接使用这两个值，比例就是相互的币价} else {//如果两个储备量不为0，需要根据当前的价格/比例去新增流动性//先通过quote计算如果输入A的数量，得出B的实际输入量uint amountBOptimal = UniswapV2Library.quote(amountADesired, reserveA, reserveB);//如果B的实际输入量<=B的期望输入数量，if (amountBOptimal <= amountBDesired) {//实际输入量需要大于等于参数中的最小数量require(amountBOptimal >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');(amountA, amountB) = (amountADesired, amountBOptimal);//得到两个的实际添加量} else {//如果上面计算的B的实际输入量大于期望输入量，就说明用户得B数量不够， 需要反过来，通过B计算A的数量， 看A的数量是否满足，//通过B计算A的数量uint amountAOptimal = UniswapV2Library.quote(amountBDesired, reserveB, reserveA);//assert(amountAOptimal <= amountADesired);//需要计算得来的A量小于等于A的预期输入量require(amountAOptimal >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');//且实际输入量，需要大于等于最小数量(amountA, amountB) = (amountAOptimal, amountBDesired);//得到两个的实际添加量}}}function addLiquidity(//添加流动性，两个代币address tokenA,address tokenB,uint amountADesired,uint amountBDesired,uint amountAMin,uint amountBMin,address to,//lp接收人，新版的uniswap前端好像不支持设置这个了uint deadline//交易的成交时间，默认是当前时间+20分钟后的时间的秒值) external virtual override ensure(deadline) returns (uint amountA, uint amountB, uint liquidity) {//调用内部方法_addLiquidity 获取到两个币实际所需要的数量(amountA, amountB) = _addLiquidity(tokenA, tokenB, amountADesired, amountBDesired, amountAMin, amountBMin);address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);//查找到pair地址TransferHelper.safeTransferFrom(tokenA, msg.sender, pair, amountA);//给pair转A数量TransferHelper.safeTransferFrom(tokenB, msg.sender, pair, amountB);//给pair转B数量liquidity = IUniswapV2Pair(pair).mint(to);//调用pair的mint方法，会有添加的lp数量返回}function addLiquidityETH(//添加流动性，其中一个币种是ethaddress token,uint amountTokenDesired,uint amountTokenMin,uint amountETHMin,//eth最小输入量；  对应的Desired在msg.valueaddress to,uint deadline) external virtual override payable ensure(deadline) returns (uint amountToken, uint amountETH, uint liquidity) {//调用内部方法_addLiquidity 获取到两个币实际所需要的数量//eth使用 weth代币替代(amountToken, amountETH) = _addLiquidity(token,WETH,amountTokenDesired,msg.value,//ethDesiredamountTokenMin,amountETHMin);address pair = UniswapV2Library.pairFor(factory, token, WETH);//获取到pair地址TransferHelper.safeTransferFrom(token, msg.sender, pair, amountToken);//给pair转代币数量IWETH(WETH).deposit{value : amountETH}();//调用weth的兑换方法，通过eth换wethassert(IWETH(WETH).transfer(pair, amountETH));//给pair转weth数量liquidity = IUniswapV2Pair(pair).mint(to);//调用pair的mint方法，会有添加的lp数量返回// refund dust eth, if any//如果传入的eth数量，大于实际所需的eth数量， 将剩余的eth返还给用户if (msg.value > amountETH) TransferHelper.safeTransferETH(msg.sender, msg.value - amountETH);}// **** REMOVE LIQUIDITY ****function removeLiquidity(//移除流动性，该方法需要先将lp代币授权给路由合约，才能代扣lpaddress tokenA,address tokenB,uint liquidity,//移除lp的数量，  转入lp得另外两个币uint amountAMin,//A的最小输出量uint amountBMin,//B的最小输出量address to,//接收两个币的地址uint deadline) public virtual override ensure(deadline) returns (uint amountA, uint amountB) {address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);//获取pair地址IUniswapV2Pair(pair).transferFrom(msg.sender, pair, liquidity);//将lp转到pair地址// send liquidity to pair(uint amount0, uint amount1) = IUniswapV2Pair(pair).burn(to);//调用pair的burn方法， 内部会将两个币的数量转给to,返回值就是两个代币的输出数量(address token0,) = UniswapV2Library.sortTokens(tokenA, tokenB);//通过排序确认两个amountA/B(amountA, amountB) = tokenA == token0 ? (amount0, amount1) : (amount1, amount0);//校验A/B的输出量需要小于参数中要求的最小量，否则交易失败require(amountA >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');require(amountB >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');}function removeLiquidityETH(//移除流动性（其中一个返还币是ETH），该方法需要先将lp代币授权给路由合约，才能代扣lpaddress token,uint liquidity,uint amountTokenMin,uint amountETHMin,//eth最小输出量address to,uint deadline) public virtual override ensure(deadline) returns (uint amountToken, uint amountETH) {//调用上面的removeLiquidity方法，传入的是WETH(amountToken, amountETH) = removeLiquidity(token,WETH,liquidity,amountTokenMin,amountETHMin,address(this),//注意！接收币的地址是路由deadline);//将代币转给toTransferHelper.safeTransfer(token, to, amountToken);IWETH(WETH).withdraw(amountETH);//将weth转换成ethTransferHelper.safeTransferETH(to, amountETH);//将eth转给to}//WithPermit的方法 可以先了解下approveAndCall 链接https://blog.csdn.net/weixin_34235105/article/details/88761932/*实际使用EIP-712链接 https://soliditydeveloper.com/erc20-permithttps://learnblockchain.cn/article/1790https://eips.ethereum.org/EIPS/eip-2612permit在前端的使用场景，就是移除流动性的时候， 有个授权实际没有发送交易，只是要求签名，签名会得到参数中的v/r/s在实际调用该移除的方法传进来， 内部验签，确认是该用户，就将移除的lp的数量，授权给路由，可以代扣lp*/function removeLiquidityWithPermit(//移除流动性，approve + transferFromaddress tokenA,address tokenB,uint liquidity,uint amountAMin,uint amountBMin,address to,uint deadline,bool approveMax, uint8 v, bytes32 r, bytes32 s//v,r,s 验签，通过就授权给路由) external virtual override returns (uint amountA, uint amountB) {/*获取到pair,调用pair的permit(内部实际就是授权给路由),*/address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);uint value = approveMax ? uint(- 1) : liquidity;IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);//最终还是调用上面的removeLiquidity方法！(amountA, amountB) = removeLiquidity(tokenA, tokenB, liquidity, amountAMin, amountBMin, to, deadline);}function removeLiquidityETHWithPermit(//WithPermit,移除时，其中一个返回ethaddress token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline,bool approveMax, uint8 v, bytes32 r, bytes32 s) external virtual override returns (uint amountToken, uint amountETH) {/*获取到pair,调用pair的permit(内部实际就是授权给路由),*/address pair = UniswapV2Library.pairFor(factory, token, WETH);uint value = approveMax ? uint(- 1) : liquidity;IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);//最终还是调用上面的removeLiquidityETH方法！(amountToken, amountETH) = removeLiquidityETH(token, liquidity, amountTokenMin, amountETHMin, to, deadline);}// **** REMOVE LIQUIDITY (supporting fee-on-transfer tokens) ****//移除流动性(需要先授权)，支持 转账会扣手续费的代币sfunction removeLiquidityETHSupportingFeeOnTransferTokens(address token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline) public virtual override ensure(deadline) returns (uint amountETH) {//实际还是调用removeLiquidity，传入的是weth,(, amountETH) = removeLiquidity(token,WETH,liquidity,amountTokenMin,//实际就是这两个值，填很小，就可以成功amountETHMin,//实际就是这两个值，填很小，就可以成功address(this),deadline);//removeLiquidity返回的第一个参数是代币数量， 由于代币转账会扣手续费，所以，实际到达路由的代币数量并没有这么多！直接取余额转出TransferHelper.safeTransfer(token, to, IERC20(token).balanceOf(address(this)));//如果转账扣两次手续费..这里相当于扣两次，pair->router, router->to//将weth转换eth,再转给to,IWETH(WETH).withdraw(amountETH);TransferHelper.safeTransferETH(to, amountETH);}//同上， 先验签授权，再调用上面的removeLiquidityETHSupportingFeeOnTransferTokensfunction removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(address token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline,bool approveMax, uint8 v, bytes32 r, bytes32 s) external virtual override returns (uint amountETH) {address pair = UniswapV2Library.pairFor(factory, token, WETH);uint value = approveMax ? uint(- 1) : liquidity;IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);amountETH = removeLiquidityETHSupportingFeeOnTransferTokens(token, liquidity, amountTokenMin, amountETHMin, to, deadline);}// **** SWAP ****// requires the initial amount to have already been sent to the first pair//交易方法//需要先将amounts[0]的金额已经转到第一个pair地址(即path[0]+path[1]组成的pair)！function _swap(uint[] memory amounts, address[] memory path, address _to) internal virtual {for (uint i; i < path.length - 1; i++) {//遍历整个path//得到进/出token地址(address input, address output) = (path[i], path[i + 1]);//排序得到token0(address token0,) = UniswapV2Library.sortTokens(input, output);//获取到output币种的输出量！uint amountOut = amounts[i + 1];//根据token0，input得到amount0需要out,还是amount1是out,; 注意其中之一一定是0，即入token的金额，不需要pair转出(uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOut) : (amountOut, uint(0));//如果i小于path长度-2，就表示还需要继续交易，所以to是下一个交易对，如果一样就表示path结束了，to就是参数中的_toaddress to = i < path.length - 2 ? UniswapV2Library.pairFor(factory, output, path[i + 2]) : _to;//调用pair的 swap方法，其中一个out是0，另一个是要转出的金额， 内部是转出输出量，并校验交易是否正确，更新储备量IUniswapV2Pair(UniswapV2Library.pairFor(factory, input, output)).swap(amount0Out, amount1Out, to, new bytes(0));}}//输入精确的token,换取另一个token(输出量不确定)function swapExactTokensForTokens(uint amountIn,//输入金额uint amountOutMin,//最小输出金额address[] calldata path,//交易路径address to,uint deadline) external virtual override ensure(deadline) returns (uint[] memory amounts) {//通过getAmountsOut获取整个path完整路径的输入/出量，下标0是用户实际输入额，最后一个位置是实际输出额amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);//需要满足计算得来最终输出量大于等于最小输出金额require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');//先将amounts[0]入金额转入第一个pair!!TransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]);//调用内部_swap方法_swap(amounts, path, to);}//输入不确定数量A，换取精确输出的B (例：精确输出1个token,正常100u可以换1个token, 由于发交易后其他人先交易过，导致价格变了，可能95或者105可以买1个token,95肯定交易通过， 如果amountInMax是102，该交易就无法成交，回退)function swapTokensForExactTokens(uint amountOut,//精确的输出额uint amountInMax,//最大允许的输入量address[] calldata path,address to,uint deadline) external virtual override ensure(deadline) returns (uint[] memory amounts) {//根据getAmountsIn 计算出输入输出量amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);//需要第一个输入量小于等于计算来的实际输入量require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');//将计算得来的金额amounts[0]转入第一个pairTransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]);//调用内部_swap方法_swap(amounts, path, to);}//输入精确的eth换取不定量的token,对应swapExactTokensForTokens，不过输入的是eth,换成weth就一样了function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)externalvirtualoverridepayableensure(deadline)returns (uint[] memory amounts){//要求path[0]是weth地址require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');//通过getAmountsOut，输入额是msg.valueamounts = UniswapV2Library.getAmountsOut(factory, msg.value, path);//需要满足计算得来最终输出量大于等于最小输出金额require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');//pair中只会存weth,没有ethIWETH(WETH).deposit{value : amounts[0]}();//兑换成weth//将weth转入到第一个pairassert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]));//调用内部_swap方法_swap(amounts, path, to);}//输入不定量的A，换取精确的输出ETH，对应swapTokensForExactTokens，只是内部将weth转成eth再给用户function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)externalvirtualoverrideensure(deadline)returns (uint[] memory amounts){//path最后一个输出地址是wethrequire(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');//amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);//需要第一个输入量小于等于计算来的实际输入量require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');//将计算得来的金额amounts[0]转入第一个pairTransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]);//调用内部_swap方法，注意第三个参数改成了当前路由地址！_swap(amounts, path, address(this));//交换成功后，将weth转换成eth,再转给toIWETH(WETH).withdraw(amounts[amounts.length - 1]);TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);}//输入精确的A换取不定量的eth swapExactTokensForTokens 只是输出是ethfunction swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)externalvirtualoverrideensure(deadline)returns (uint[] memory amounts){//path最后一个输出地址是wethrequire(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');//amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);//注意输出要大于最小输出require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');//TransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]);//调用内部_swap方法，注意第三个参数改成了当前路由地址！_swap(amounts, path, address(this));//交换成功后，将weth转换成eth,再转给toIWETH(WETH).withdraw(amounts[amounts.length - 1]);TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);}//输入不定量的ETH换取精确的token输出，对应swapTokensForExactTokens，只是输入的是ethfunction swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)externalvirtualoverridepayableensure(deadline)returns (uint[] memory amounts){require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);//注意，实际输入需要小于msg.value,即eth输入量require(amounts[0] <= msg.value, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');IWETH(WETH).deposit{value : amounts[0]}();assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]));_swap(amounts, path, to);// refund dust eth, if any//如果实际不需要那么多eth,将剩余返还用户if (msg.value > amounts[0]) TransferHelper.safeTransferETH(msg.sender, msg.value - amounts[0]);}// **** SWAP (supporting fee-on-transfer tokens) ****// requires the initial amount to have already been sent to the first pair//交易方法，支持转账扣手续费的代币//需要先将amounts[0]的金额已经转到第一个pair地址(即path[0]+path[1]组成的pair)！function _swapSupportingFeeOnTransferTokens(address[] memory path, address _to) internal virtual {for (uint i; i < path.length - 1; i++) {//得到进/出token地址(address input, address output) = (path[i], path[i + 1]);//排序得到token0(address token0,) = UniswapV2Library.sortTokens(input, output);//获取pairIUniswapV2Pair pair = IUniswapV2Pair(UniswapV2Library.pairFor(factory, input, output));uint amountInput;//输入金额uint amountOutput;//输入金额{// scope to avoid stack too deep errors 避免堆栈太深错误，用{}括部分临时变量//或许两个币的储备量(uint reserve0, uint reserve1,) = pair.getReserves();//根据input,token0 得出 inToken的储备量,outToken的储备量(uint reserveInput, uint reserveOutput) = input == token0 ? (reserve0, reserve1) : (reserve1, reserve0);//查询交易对的inToken余额，减掉最后记录的储备量，就是交易对实际获取到的inToken数量(TODO 和_swap的区别就在这里，不是使用计算来的amounts[0]作为输入，而是通过查询pair余额再减去最后更新的储备量得到实际pair到账额！)amountInput = IERC20(input).balanceOf(address(pair)).sub(reserveInput);//通过实际得到的input量，计算实际会输出的output数量amountOutput = UniswapV2Library.getAmountOut(amountInput, reserveInput, reserveOutput);}//根据token0，input得到amount0需要out,还是amount1是out,; 注意其中之一一定是0，即入token的金额，不需要pair转出(uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOutput) : (amountOutput, uint(0));//如果i小于path长度-2，就表示还需要继续交易，所以to是下一个交易对，如果一样就表示path结束了，to就是参数中的_toaddress to = i < path.length - 2 ? UniswapV2Library.pairFor(factory, output, path[i + 2]) : _to;//调用pair的 swap方法，其中一个out是0，另一个是要转出的金额， 内部是转出输出量，并校验交易是否正确，更新储备量pair.swap(amount0Out, amount1Out, to, new bytes(0));}}/**TODO 带supportingFeeOnTransfer方法都是通过余额的方式计算输入/出下面的三个方法， 都是swapExactXXXForXX, 而没有swapXXXForExactXX如果是自己开发合约调用，可以随意选用哪个swap在uniswap中，如果滑点改成49，会自动切换带supportingFeeOnTransfer的方法还有些其他情况也会自动切，这个会前端的可以看看代码，什么情况下，前端会选择使用带supportingFeeOnTransfer的方法去交易*///输入精确的token,换取另一个token，支持转账时扣手续费的tokenfunction swapExactTokensForTokensSupportingFeeOnTransferTokens(uint amountIn,//输入金额uint amountOutMin,//最小输出金额，该金额只要够小，交易就一定可以成功address[] calldata path,//交换路径address to,uint deadline) external virtual override ensure(deadline) {//将输入金额转到第一个pair地址TransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn);//查询to用户当前最终输出token的余额uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);//调用内部交易方法_swapSupportingFeeOnTransferTokens(path, to);//通过查询余额的方式，校验交易前后的余额差，大于等于最小输出！require(IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');}//输入精确eth换取另一个tokenfunction swapExactETHForTokensSupportingFeeOnTransferTokens(uint amountOutMin,address[] calldata path,address to,uint deadline)externalvirtualoverridepayableensure(deadline){require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');//将eth转成weth,并转给第一个pair地址uint amountIn = msg.value;IWETH(WETH).deposit{value : amountIn}();assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn));//跟上面方法一样， 通过查询余额的方式校验uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);_swapSupportingFeeOnTransferTokens(path, to);require(IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');}//输入精确token换取输出eth,function swapExactTokensForETHSupportingFeeOnTransferTokens(uint amountIn,uint amountOutMin,address[] calldata path,address to,uint deadline)externalvirtualoverrideensure(deadline){require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');TransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn);_swapSupportingFeeOnTransferTokens(path, address(this));uint amountOut = IERC20(WETH).balanceOf(address(this));require(amountOut >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');IWETH(WETH).withdraw(amountOut);TransferHelper.safeTransferETH(to, amountOut);}// **** LIBRARY FUNCTIONS ****//以下方法，都是library里面的方法，代调用UniswapV2Libraryfunction quote(uint amountA, uint reserveA, uint reserveB) public pure virtual override returns (uint amountB) {return UniswapV2Library.quote(amountA, reserveA, reserveB);}function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut)publicpurevirtualoverridereturns (uint amountOut){return UniswapV2Library.getAmountOut(amountIn, reserveIn, reserveOut);}function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut)publicpurevirtualoverridereturns (uint amountIn){return UniswapV2Library.getAmountIn(amountOut, reserveIn, reserveOut);}function getAmountsOut(uint amountIn, address[] memory path)publicviewvirtualoverridereturns (uint[] memory amounts){return UniswapV2Library.getAmountsOut(factory, amountIn, path);}function getAmountsIn(uint amountOut, address[] memory path)publicviewvirtualoverridereturns (uint[] memory amounts){return UniswapV2Library.getAmountsIn(factory, amountOut, path);}
}// a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)library SafeMath {function add(uint x, uint y) internal pure returns (uint z) {require((z = x + y) >= x, 'ds-math-add-overflow');}function sub(uint x, uint y) internal pure returns (uint z) {require((z = x - y) <= x, 'ds-math-sub-underflow');}function mul(uint x, uint y) internal pure returns (uint z) {require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');}
}library UniswapV2Library {using SafeMath for uint;// returns sorted token addresses, used to handle return values from pairs sorted in this order//两个token排序，address实际也是一个uint160，可以相关转换，所以可以比大小，排序,小是0，确认在交易对中的token0,token1function sortTokens(address tokenA, address tokenB) internal pure returns (address token0, address token1) {require(tokenA != tokenB, 'UniswapV2Library: IDENTICAL_ADDRESSES');(token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);require(token0 != address(0), 'UniswapV2Library: ZERO_ADDRESS');}// calculates the CREATE2 address for a pair without making any external calls// 通过create2的方式计算交易对的地址，注意initCode,每次部署的时候，可能都不一样，需要生成//用法套格式即可，对应factory中的createPair， 要深入的，可以具体去了解下create2function pairFor(address factory, address tokenA, address tokenB) internal pure returns (address pair) {(address token0, address token1) = sortTokens(tokenA, tokenB);pair = address(uint(keccak256(abi.encodePacked(hex'ff',factory,keccak256(abi.encodePacked(token0, token1)),hex'96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f' // init code hash))));}// fetches and sorts the reserves for a pair//获取两个币的储备量， 通过pair查询， 内部返回值会根据入参的币种进行调整位置返回function getReserves(address factory, address tokenA, address tokenB) internal view returns (uint reserveA, uint reserveB) {(address token0,) = sortTokens(tokenA, tokenB);(uint reserve0, uint reserve1,) = IUniswapV2Pair(pairFor(factory, tokenA, tokenB)).getReserves();(reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);}// given some amount of an asset and pair reserves, returns an equivalent amount of the other asset// 添加流动性的时候，通过该方法查询输入A的数量，需要多少个Bfunction quote(uint amountA, uint reserveA, uint reserveB) internal pure returns (uint amountB) {//判断数量， 首次添加流动性，随意定价，不需要查询该方法require(amountA > 0, 'UniswapV2Library: INSUFFICIENT_AMOUNT');require(reserveA > 0 && reserveB > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');//B数量 = 预期输入A的数量 * B的储备量 / A的储备量；  //实际公式就是 A/B = reserveA/reserveB, 两个币的数量比例一致amountB = amountA.mul(reserveB) / reserveA;}// given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset//通过精确输入金额,输入币的储备量，输出币的储备量，计算输出币的最大输出量function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) internal pure returns (uint amountOut) {require(amountIn > 0, 'UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT');require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');//具体看下面的公式推导，要看该公式，首先要理解uniswap AMM, X * Y= Kuint amountInWithFee = amountIn.mul(997);//手续费都是扣输入额的千三，所以需要去掉千三后才是实际用于交易的金额uint numerator = amountInWithFee.mul(reserveOut);//套下面公式理解吧！！uint denominator = reserveIn.mul(1000).add(amountInWithFee);amountOut = numerator / denominator;/**   查看下面的由in计算out公式 out = in * f * rOut / rIn + in *f*   手续费是千三， 扣除手续费后去交易的金额是输入额的0.997, 公式中的f是0.997 内部计算用的uint,所以分子分母都 * 1000*   最终的公式是    out = in * 997 * rOut / ((rIn + in *f) * 1000)*                  out = in * 997 * rOut / (rIn*1000 + in * 997)*/}/***** 推导公式* in 输入金额， out 输出金额* rIn tokenIn的流动性， rOut，tokenOut的流动性* fee 手续费，注：当前带入0.997   也就是997/1000** 两个计算公式实际是一样的， 只是一个求in,一个求out* (rIn + in * f) * (rOut - out) = rIn * rOut*** 由out计算in  getAmountIn* (rIn + in * f) * (rOut - out) = rIn * rOut* rIn * rOut + in * f * rOut  - rIn * out - in * f * out = rIn * rOut* rIn * out = in * f * rOut - in * f * out* in = rIn * out / (f * (rOut - out)) + 1  (尾部的 +1应该是避免精度计算，最后一位小了，会成交不了)*** 由in计算out  getAmountOut* (rIn + in * f) * (rOut - out) = rIn * rOut* rIn * rOut + in * f * rOut  - rIn * out - in * f * out = rIn * rOut* in * f * rOut = rIn * out + in * f * out* out = in * f * rOut / rIn + in *f**/// given an output amount of an asset and pair reserves, returns a required input amount of the other asset//通过精确的输出量，输入币的储备量，输出币的储备量，计算所需的输入币的数量function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) internal pure returns (uint amountIn) {require(amountOut > 0, 'UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT');require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');//先看上面的由out计算in 公式推导uint numerator = reserveIn.mul(amountOut).mul(1000);//对应公式中的rIn * out, 乘以1000是0.997需要换算成整数uint denominator = reserveOut.sub(amountOut).mul(997);//对应上面的分母 (f * (rOut - out)),乘以1000后就是 997 * (rOut - out)amountIn = (numerator / denominator).add(1);}// performs chained getAmountOut calculations on any number of pairs// 根据path,计算出每个交易对的输入/输出量(如果path>2,前一个交易对的输出量，就是下一个交易对交易的输入量)//内部实际还是调用的上面getAmountOut方法， 返回值amounts长度和path的长度一致，function getAmountsOut(address factory, uint amountIn, address[] memory path) internal view returns (uint[] memory amounts) {require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');amounts = new uint[](path.length);//创建数组amounts[0] = amountIn;//0位置是输入量for (uint i; i < path.length - 1; i++) {//每两个token组成一个交易对，计算out(uint reserveIn, uint reserveOut) = getReserves(factory, path[i], path[i + 1]);amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);}}// performs chained getAmountIn calculations on any number of pairs// 根据path,计算出每个交易对的输入/输出量(如果path>2,前一个交易对的输出量，就是下一个交易对交易的输入量)//内部实际还是调用的上面getAmountIn方法， 返回值amounts长度和path的长度一致，function getAmountsIn(address factory, uint amountOut, address[] memory path) internal view returns (uint[] memory amounts) {require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');amounts = new uint[](path.length);amounts[amounts.length - 1] = amountOut;//最后一个是入参out,for (uint i = path.length - 1; i > 0; i--) {//倒序遍历计算(uint reserveIn, uint reserveOut) = getReserves(factory, path[i - 1], path[i]);amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);}}
}// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
//转账工具类
library TransferHelper {function safeApprove(address token, address to, uint value) internal {// bytes4(keccak256(bytes('approve(address,uint256)')));(bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: APPROVE_FAILED');}//注：data.length == 0,主要针对的是usdt, 同时！该方法在波场不适用！！ 波场的的U 有返回data,但是一直是false!!function safeTransfer(address token, address to, uint value) internal {// bytes4(keccak256(bytes('transfer(address,uint256)')));(bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FAILED');}function safeTransferFrom(address token, address from, address to, uint value) internal {// bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));(bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FROM_FAILED');}function safeTransferETH(address to, uint value) internal {(bool success,) = to.call{value : value}(new bytes(0));require(success, 'TransferHelper: ETH_TRANSFER_FAILED');}
}

UniswapV2Router02

/***Submitted for verification at Etherscan.io on 2020-06-05https://etherscan.io/address/0x7a250d5630b4cf539739df2c5dacb4c659f2488d#contracts
*/pragma solidity =0.6.6;interface IUniswapV2Factory {event PairCreated(address indexed token0, address indexed token1, address pair, uint);function feeTo() external view returns (address);function feeToSetter() external view returns (address);function getPair(address tokenA, address tokenB) external view returns (address pair);function allPairs(uint) external view returns (address pair);function allPairsLength() external view returns (uint);function createPair(address tokenA, address tokenB) external returns (address pair);function setFeeTo(address) external;function setFeeToSetter(address) external;
}interface IUniswapV2Pair {event Approval(address indexed owner, address indexed spender, uint value);event Transfer(address indexed from, address indexed to, uint value);function name() external pure returns (string memory);function symbol() external pure returns (string memory);function decimals() external pure returns (uint8);function totalSupply() external view returns (uint);function balanceOf(address owner) external view returns (uint);function allowance(address owner, address spender) external view returns (uint);function approve(address spender, uint value) external returns (bool);function transfer(address to, uint value) external returns (bool);function transferFrom(address from, address to, uint value) external returns (bool);function DOMAIN_SEPARATOR() external view returns (bytes32);function PERMIT_TYPEHASH() external pure returns (bytes32);function nonces(address owner) external view returns (uint);function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;event Mint(address indexed sender, uint amount0, uint amount1);event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);event Swap(address indexed sender,uint amount0In,uint amount1In,uint amount0Out,uint amount1Out,address indexed to);event Sync(uint112 reserve0, uint112 reserve1);function MINIMUM_LIQUIDITY() external pure returns (uint);function factory() external view returns (address);function token0() external view returns (address);function token1() external view returns (address);function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);function price0CumulativeLast() external view returns (uint);function price1CumulativeLast() external view returns (uint);function kLast() external view returns (uint);function mint(address to) external returns (uint liquidity);function burn(address to) external returns (uint amount0, uint amount1);function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;function skim(address to) external;function sync() external;function initialize(address, address) external;
}interface IUniswapV2Router01 {function factory() external pure returns (address);function WETH() external pure returns (address);function addLiquidity(address tokenA,address tokenB,uint amountADesired,uint amountBDesired,uint amountAMin,uint amountBMin,address to,uint deadline) external returns (uint amountA, uint amountB, uint liquidity);function addLiquidityETH(address token,uint amountTokenDesired,uint amountTokenMin,uint amountETHMin,address to,uint deadline) external payable returns (uint amountToken, uint amountETH, uint liquidity);function removeLiquidity(address tokenA,address tokenB,uint liquidity,uint amountAMin,uint amountBMin,address to,uint deadline) external returns (uint amountA, uint amountB);function removeLiquidityETH(address token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline) external returns (uint amountToken, uint amountETH);function removeLiquidityWithPermit(address tokenA,address tokenB,uint liquidity,uint amountAMin,uint amountBMin,address to,uint deadline,bool approveMax, uint8 v, bytes32 r, bytes32 s) external returns (uint amountA, uint amountB);function removeLiquidityETHWithPermit(address token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline,bool approveMax, uint8 v, bytes32 r, bytes32 s) external returns (uint amountToken, uint amountETH);function swapExactTokensForTokens(uint amountIn,uint amountOutMin,address[] calldata path,address to,uint deadline) external returns (uint[] memory amounts);function swapTokensForExactTokens(uint amountOut,uint amountInMax,address[] calldata path,address to,uint deadline) external returns (uint[] memory amounts);function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)externalpayablereturns (uint[] memory amounts);function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)externalreturns (uint[] memory amounts);function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)externalreturns (uint[] memory amounts);function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)externalpayablereturns (uint[] memory amounts);function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}interface IUniswapV2Router02 is IUniswapV2Router01 {function removeLiquidityETHSupportingFeeOnTransferTokens(address token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline) external returns (uint amountETH);function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(address token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline,bool approveMax, uint8 v, bytes32 r, bytes32 s) external returns (uint amountETH);function swapExactTokensForTokensSupportingFeeOnTransferTokens(uint amountIn,uint amountOutMin,address[] calldata path,address to,uint deadline) external;function swapExactETHForTokensSupportingFeeOnTransferTokens(uint amountOutMin,address[] calldata path,address to,uint deadline) external payable;function swapExactTokensForETHSupportingFeeOnTransferTokens(uint amountIn,uint amountOutMin,address[] calldata path,address to,uint deadline) external;
}interface IERC20 {event Approval(address indexed owner, address indexed spender, uint value);event Transfer(address indexed from, address indexed to, uint value);function name() external view returns (string memory);function symbol() external view returns (string memory);function decimals() external view returns (uint8);function totalSupply() external view returns (uint);function balanceOf(address owner) external view returns (uint);function allowance(address owner, address spender) external view returns (uint);function approve(address spender, uint value) external returns (bool);function transfer(address to, uint value) external returns (bool);function transferFrom(address from, address to, uint value) external returns (bool);
}interface IWETH {function deposit() external payable;function transfer(address to, uint value) external returns (bool);function withdraw(uint) external;
}contract UniswapV2Router02 is IUniswapV2Router02 {using SafeMath for uint;address public  immutable override factory;address public  immutable override WETH;//交易时间是否过期，dapp中默认设置时20分钟内成交有效modifier ensure(uint deadline) {require(deadline >= block.timestamp, 'UniswapV2Router: EXPIRED');_;}constructor(address _factory, address _WETH) public {factory = _factory;WETH = _WETH;}receive() external payable {assert(msg.sender == WETH); // only accept ETH via fallback from the WETH contract}// **** ADD LIQUIDITY ****//添加流动性内部方法，通过该方法计算出两个币的实际所需数量function _addLiquidity(address tokenA,//代币地址Aaddress tokenB,//代币地址Buint amountADesired,//代币A 期望添加量uint amountBDesired,//代币B 期望添加量uint amountAMin,//代币A 最小添加量(这两个min,收益添加的时候可以和Desired一样， 二次添加的时候，一般都是小于Desired，具体小多少，算法可以查看uniswap前端代码)uint amountBMin//代币B 最小添加量) internal virtual returns (uint amountA, uint amountB) {//返回值是两个// create the pair if it doesn't exist yet//通过factory,查询pair,如果等于0地址，就表示还没有该交易对，调用创建方法if (IUniswapV2Factory(factory).getPair(tokenA, tokenB) == address(0)) {IUniswapV2Factory(factory).createPair(tokenA, tokenB);//创建交易对}//可以先了解下UniswapV2Library 中相关方法的意思//如果查询两个值都是0，首次添加，直接使用期望值(uint reserveA, uint reserveB) = UniswapV2Library.getReserves(factory, tokenA, tokenB);if (reserveA == 0 && reserveB == 0) {(amountA, amountB) = (amountADesired, amountBDesired);//直接使用这两个值，比例就是相互的币价} else {//如果两个储备量不为0，需要根据当前的价格/比例去新增流动性//先通过quote计算如果输入A的数量，得出B的实际输入量uint amountBOptimal = UniswapV2Library.quote(amountADesired, reserveA, reserveB);//如果B的实际输入量<=B的期望输入数量，if (amountBOptimal <= amountBDesired) {//实际输入量需要大于等于参数中的最小数量require(amountBOptimal >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');(amountA, amountB) = (amountADesired, amountBOptimal);//得到两个的实际添加量} else {//如果上面计算的B的实际输入量大于期望输入量，就说明用户得B数量不够， 需要反过来，通过B计算A的数量， 看A的数量是否满足，//通过B计算A的数量uint amountAOptimal = UniswapV2Library.quote(amountBDesired, reserveB, reserveA);//assert(amountAOptimal <= amountADesired);//需要计算得来的A量小于等于A的预期输入量require(amountAOptimal >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');//且实际输入量，需要大于等于最小数量(amountA, amountB) = (amountAOptimal, amountBDesired);//得到两个的实际添加量}}}function addLiquidity(//添加流动性，两个代币address tokenA,address tokenB,uint amountADesired,uint amountBDesired,uint amountAMin,uint amountBMin,address to,//lp接收人，新版的uniswap前端好像不支持设置这个了uint deadline//交易的成交时间，默认是当前时间+20分钟后的时间的秒值) external virtual override ensure(deadline) returns (uint amountA, uint amountB, uint liquidity) {//调用内部方法_addLiquidity 获取到两个币实际所需要的数量(amountA, amountB) = _addLiquidity(tokenA, tokenB, amountADesired, amountBDesired, amountAMin, amountBMin);address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);//查找到pair地址TransferHelper.safeTransferFrom(tokenA, msg.sender, pair, amountA);//给pair转A数量TransferHelper.safeTransferFrom(tokenB, msg.sender, pair, amountB);//给pair转B数量liquidity = IUniswapV2Pair(pair).mint(to);//调用pair的mint方法，会有添加的lp数量返回}function addLiquidityETH(//添加流动性，其中一个币种是ethaddress token,uint amountTokenDesired,uint amountTokenMin,uint amountETHMin,//eth最小输入量；  对应的Desired在msg.valueaddress to,uint deadline) external virtual override payable ensure(deadline) returns (uint amountToken, uint amountETH, uint liquidity) {//调用内部方法_addLiquidity 获取到两个币实际所需要的数量//eth使用 weth代币替代(amountToken, amountETH) = _addLiquidity(token,WETH,amountTokenDesired,msg.value,//ethDesiredamountTokenMin,amountETHMin);address pair = UniswapV2Library.pairFor(factory, token, WETH);//获取到pair地址TransferHelper.safeTransferFrom(token, msg.sender, pair, amountToken);//给pair转代币数量IWETH(WETH).deposit{value : amountETH}();//调用weth的兑换方法，通过eth换wethassert(IWETH(WETH).transfer(pair, amountETH));//给pair转weth数量liquidity = IUniswapV2Pair(pair).mint(to);//调用pair的mint方法，会有添加的lp数量返回// refund dust eth, if any//如果传入的eth数量，大于实际所需的eth数量， 将剩余的eth返还给用户if (msg.value > amountETH) TransferHelper.safeTransferETH(msg.sender, msg.value - amountETH);}// **** REMOVE LIQUIDITY ****function removeLiquidity(//移除流动性，该方法需要先将lp代币授权给路由合约，才能代扣lpaddress tokenA,address tokenB,uint liquidity,//移除lp的数量，  转入lp得另外两个币uint amountAMin,//A的最小输出量uint amountBMin,//B的最小输出量address to,//接收两个币的地址uint deadline) public virtual override ensure(deadline) returns (uint amountA, uint amountB) {address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);//获取pair地址IUniswapV2Pair(pair).transferFrom(msg.sender, pair, liquidity);//将lp转到pair地址// send liquidity to pair(uint amount0, uint amount1) = IUniswapV2Pair(pair).burn(to);//调用pair的burn方法， 内部会将两个币的数量转给to,返回值就是两个代币的输出数量(address token0,) = UniswapV2Library.sortTokens(tokenA, tokenB);//通过排序确认两个amountA/B(amountA, amountB) = tokenA == token0 ? (amount0, amount1) : (amount1, amount0);//校验A/B的输出量需要小于参数中要求的最小量，否则交易失败require(amountA >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');require(amountB >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');}function removeLiquidityETH(//移除流动性（其中一个返还币是ETH），该方法需要先将lp代币授权给路由合约，才能代扣lpaddress token,uint liquidity,uint amountTokenMin,uint amountETHMin,//eth最小输出量address to,uint deadline) public virtual override ensure(deadline) returns (uint amountToken, uint amountETH) {//调用上面的removeLiquidity方法，传入的是WETH(amountToken, amountETH) = removeLiquidity(token,WETH,liquidity,amountTokenMin,amountETHMin,address(this),//注意！接收币的地址是路由deadline);//将代币转给toTransferHelper.safeTransfer(token, to, amountToken);IWETH(WETH).withdraw(amountETH);//将weth转换成ethTransferHelper.safeTransferETH(to, amountETH);//将eth转给to}//WithPermit的方法 可以先了解下approveAndCall 链接https://blog.csdn.net/weixin_34235105/article/details/88761932/*实际使用EIP-712链接 https://soliditydeveloper.com/erc20-permithttps://learnblockchain.cn/article/1790https://eips.ethereum.org/EIPS/eip-2612permit在前端的使用场景，就是移除流动性的时候， 有个授权实际没有发送交易，只是要求签名，签名会得到参数中的v/r/s在实际调用该移除的方法传进来， 内部验签，确认是该用户，就将移除的lp的数量，授权给路由，可以代扣lp*/function removeLiquidityWithPermit(//移除流动性，approve + transferFromaddress tokenA,address tokenB,uint liquidity,uint amountAMin,uint amountBMin,address to,uint deadline,bool approveMax, uint8 v, bytes32 r, bytes32 s//v,r,s 验签，通过就授权给路由) external virtual override returns (uint amountA, uint amountB) {/*获取到pair,调用pair的permit(内部实际就是授权给路由),*/address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);uint value = approveMax ? uint(- 1) : liquidity;IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);//最终还是调用上面的removeLiquidity方法！(amountA, amountB) = removeLiquidity(tokenA, tokenB, liquidity, amountAMin, amountBMin, to, deadline);}function removeLiquidityETHWithPermit(//WithPermit,移除时，其中一个返回ethaddress token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline,bool approveMax, uint8 v, bytes32 r, bytes32 s) external virtual override returns (uint amountToken, uint amountETH) {/*获取到pair,调用pair的permit(内部实际就是授权给路由),*/address pair = UniswapV2Library.pairFor(factory, token, WETH);uint value = approveMax ? uint(- 1) : liquidity;IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);//最终还是调用上面的removeLiquidityETH方法！(amountToken, amountETH) = removeLiquidityETH(token, liquidity, amountTokenMin, amountETHMin, to, deadline);}// **** REMOVE LIQUIDITY (supporting fee-on-transfer tokens) ****//移除流动性(需要先授权)，支持 转账会扣手续费的代币sfunction removeLiquidityETHSupportingFeeOnTransferTokens(address token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline) public virtual override ensure(deadline) returns (uint amountETH) {//实际还是调用removeLiquidity，传入的是weth,(, amountETH) = removeLiquidity(token,WETH,liquidity,amountTokenMin,//实际就是这两个值，填很小，就可以成功amountETHMin,//实际就是这两个值，填很小，就可以成功address(this),deadline);//removeLiquidity返回的第一个参数是代币数量， 由于代币转账会扣手续费，所以，实际到达路由的代币数量并没有这么多！直接取余额转出TransferHelper.safeTransfer(token, to, IERC20(token).balanceOf(address(this)));//如果转账扣两次手续费..这里相当于扣两次，pair->router, router->to//将weth转换eth,再转给to,IWETH(WETH).withdraw(amountETH);TransferHelper.safeTransferETH(to, amountETH);}//同上， 先验签授权，再调用上面的removeLiquidityETHSupportingFeeOnTransferTokensfunction removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(address token,uint liquidity,uint amountTokenMin,uint amountETHMin,address to,uint deadline,bool approveMax, uint8 v, bytes32 r, bytes32 s) external virtual override returns (uint amountETH) {address pair = UniswapV2Library.pairFor(factory, token, WETH);uint value = approveMax ? uint(- 1) : liquidity;IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);amountETH = removeLiquidityETHSupportingFeeOnTransferTokens(token, liquidity, amountTokenMin, amountETHMin, to, deadline);}// **** SWAP ****// requires the initial amount to have already been sent to the first pair//交易方法//需要先将amounts[0]的金额已经转到第一个pair地址(即path[0]+path[1]组成的pair)！function _swap(uint[] memory amounts, address[] memory path, address _to) internal virtual {for (uint i; i < path.length - 1; i++) {//遍历整个path//得到进/出token地址(address input, address output) = (path[i], path[i + 1]);//排序得到token0(address token0,) = UniswapV2Library.sortTokens(input, output);//获取到output币种的输出量！uint amountOut = amounts[i + 1];//根据token0，input得到amount0需要out,还是amount1是out,; 注意其中之一一定是0，即入token的金额，不需要pair转出(uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOut) : (amountOut, uint(0));//如果i小于path长度-2，就表示还需要继续交易，所以to是下一个交易对，如果一样就表示path结束了，to就是参数中的_toaddress to = i < path.length - 2 ? UniswapV2Library.pairFor(factory, output, path[i + 2]) : _to;//调用pair的 swap方法，其中一个out是0，另一个是要转出的金额， 内部是转出输出量，并校验交易是否正确，更新储备量IUniswapV2Pair(UniswapV2Library.pairFor(factory, input, output)).swap(amount0Out, amount1Out, to, new bytes(0));}}//输入精确的token,换取另一个token(输出量不确定)function swapExactTokensForTokens(uint amountIn,//输入金额uint amountOutMin,//最小输出金额address[] calldata path,//交易路径address to,uint deadline) external virtual override ensure(deadline) returns (uint[] memory amounts) {//通过getAmountsOut获取整个path完整路径的输入/出量，下标0是用户实际输入额，最后一个位置是实际输出额amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);//需要满足计算得来最终输出量大于等于最小输出金额require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');//先将amounts[0]入金额转入第一个pair!!TransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]);//调用内部_swap方法_swap(amounts, path, to);}//输入不确定数量A，换取精确输出的B (例：精确输出1个token,正常100u可以换1个token, 由于发交易后其他人先交易过，导致价格变了，可能95或者105可以买1个token,95肯定交易通过， 如果amountInMax是102，该交易就无法成交，回退)function swapTokensForExactTokens(uint amountOut,//精确的输出额uint amountInMax,//最大允许的输入量address[] calldata path,address to,uint deadline) external virtual override ensure(deadline) returns (uint[] memory amounts) {//根据getAmountsIn 计算出输入输出量amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);//需要第一个输入量小于等于计算来的实际输入量require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');//将计算得来的金额amounts[0]转入第一个pairTransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]);//调用内部_swap方法_swap(amounts, path, to);}//输入精确的eth换取不定量的token,对应swapExactTokensForTokens，不过输入的是eth,换成weth就一样了function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)externalvirtualoverridepayableensure(deadline)returns (uint[] memory amounts){//要求path[0]是weth地址require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');//通过getAmountsOut，输入额是msg.valueamounts = UniswapV2Library.getAmountsOut(factory, msg.value, path);//需要满足计算得来最终输出量大于等于最小输出金额require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');//pair中只会存weth,没有ethIWETH(WETH).deposit{value : amounts[0]}();//兑换成weth//将weth转入到第一个pairassert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]));//调用内部_swap方法_swap(amounts, path, to);}//输入不定量的A，换取精确的输出ETH，对应swapTokensForExactTokens，只是内部将weth转成eth再给用户function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)externalvirtualoverrideensure(deadline)returns (uint[] memory amounts){//path最后一个输出地址是wethrequire(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');//amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);//需要第一个输入量小于等于计算来的实际输入量require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');//将计算得来的金额amounts[0]转入第一个pairTransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]);//调用内部_swap方法，注意第三个参数改成了当前路由地址！_swap(amounts, path, address(this));//交换成功后，将weth转换成eth,再转给toIWETH(WETH).withdraw(amounts[amounts.length - 1]);TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);}//输入精确的A换取不定量的eth swapExactTokensForTokens 只是输出是ethfunction swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)externalvirtualoverrideensure(deadline)returns (uint[] memory amounts){//path最后一个输出地址是wethrequire(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');//amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);//注意输出要大于最小输出require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');//TransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]);//调用内部_swap方法，注意第三个参数改成了当前路由地址！_swap(amounts, path, address(this));//交换成功后，将weth转换成eth,再转给toIWETH(WETH).withdraw(amounts[amounts.length - 1]);TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);}//输入不定量的ETH换取精确的token输出，对应swapTokensForExactTokens，只是输入的是ethfunction swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)externalvirtualoverridepayableensure(deadline)returns (uint[] memory amounts){require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);//注意，实际输入需要小于msg.value,即eth输入量require(amounts[0] <= msg.value, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');IWETH(WETH).deposit{value : amounts[0]}();assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]));_swap(amounts, path, to);// refund dust eth, if any//如果实际不需要那么多eth,将剩余返还用户if (msg.value > amounts[0]) TransferHelper.safeTransferETH(msg.sender, msg.value - amounts[0]);}// **** SWAP (supporting fee-on-transfer tokens) ****// requires the initial amount to have already been sent to the first pair//交易方法，支持转账扣手续费的代币//需要先将amounts[0]的金额已经转到第一个pair地址(即path[0]+path[1]组成的pair)！function _swapSupportingFeeOnTransferTokens(address[] memory path, address _to) internal virtual {for (uint i; i < path.length - 1; i++) {//得到进/出token地址(address input, address output) = (path[i], path[i + 1]);//排序得到token0(address token0,) = UniswapV2Library.sortTokens(input, output);//获取pairIUniswapV2Pair pair = IUniswapV2Pair(UniswapV2Library.pairFor(factory, input, output));uint amountInput;//输入金额uint amountOutput;//输入金额{// scope to avoid stack too deep errors 避免堆栈太深错误，用{}括部分临时变量//或许两个币的储备量(uint reserve0, uint reserve1,) = pair.getReserves();//根据input,token0 得出 inToken的储备量,outToken的储备量(uint reserveInput, uint reserveOutput) = input == token0 ? (reserve0, reserve1) : (reserve1, reserve0);//查询交易对的inToken余额，减掉最后记录的储备量，就是交易对实际获取到的inToken数量(TODO 和_swap的区别就在这里，不是使用计算来的amounts[0]作为输入，而是通过查询pair余额再减去最后更新的储备量得到实际pair到账额！)amountInput = IERC20(input).balanceOf(address(pair)).sub(reserveInput);//通过实际得到的input量，计算实际会输出的output数量amountOutput = UniswapV2Library.getAmountOut(amountInput, reserveInput, reserveOutput);}//根据token0，input得到amount0需要out,还是amount1是out,; 注意其中之一一定是0，即入token的金额，不需要pair转出(uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOutput) : (amountOutput, uint(0));//如果i小于path长度-2，就表示还需要继续交易，所以to是下一个交易对，如果一样就表示path结束了，to就是参数中的_toaddress to = i < path.length - 2 ? UniswapV2Library.pairFor(factory, output, path[i + 2]) : _to;//调用pair的 swap方法，其中一个out是0，另一个是要转出的金额， 内部是转出输出量，并校验交易是否正确，更新储备量pair.swap(amount0Out, amount1Out, to, new bytes(0));}}/**TODO 带supportingFeeOnTransfer方法都是通过余额的方式计算输入/出下面的三个方法， 都是swapExactXXXForXX, 而没有swapXXXForExactXX如果是自己开发合约调用，可以随意选用哪个swap在uniswap中，如果滑点改成49，会自动切换带supportingFeeOnTransfer的方法还有些其他情况也会自动切，这个会前端的可以看看代码，什么情况下，前端会选择使用带supportingFeeOnTransfer的方法去交易*///输入精确的token,换取另一个token，支持转账时扣手续费的tokenfunction swapExactTokensForTokensSupportingFeeOnTransferTokens(uint amountIn,//输入金额uint amountOutMin,//最小输出金额，该金额只要够小，交易就一定可以成功address[] calldata path,//交换路径address to,uint deadline) external virtual override ensure(deadline) {//将输入金额转到第一个pair地址TransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn);//查询to用户当前最终输出token的余额uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);//调用内部交易方法_swapSupportingFeeOnTransferTokens(path, to);//通过查询余额的方式，校验交易前后的余额差，大于等于最小输出！require(IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');}//输入精确eth换取另一个tokenfunction swapExactETHForTokensSupportingFeeOnTransferTokens(uint amountOutMin,address[] calldata path,address to,uint deadline)externalvirtualoverridepayableensure(deadline){require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');//将eth转成weth,并转给第一个pair地址uint amountIn = msg.value;IWETH(WETH).deposit{value : amountIn}();assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn));//跟上面方法一样， 通过查询余额的方式校验uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);_swapSupportingFeeOnTransferTokens(path, to);require(IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');}//输入精确token换取输出eth,function swapExactTokensForETHSupportingFeeOnTransferTokens(uint amountIn,uint amountOutMin,address[] calldata path,address to,uint deadline)externalvirtualoverrideensure(deadline){require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');TransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn);_swapSupportingFeeOnTransferTokens(path, address(this));uint amountOut = IERC20(WETH).balanceOf(address(this));require(amountOut >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');IWETH(WETH).withdraw(amountOut);TransferHelper.safeTransferETH(to, amountOut);}// **** LIBRARY FUNCTIONS ****//以下方法，都是library里面的方法，代调用UniswapV2Libraryfunction quote(uint amountA, uint reserveA, uint reserveB) public pure virtual override returns (uint amountB) {return UniswapV2Library.quote(amountA, reserveA, reserveB);}function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut)publicpurevirtualoverridereturns (uint amountOut){return UniswapV2Library.getAmountOut(amountIn, reserveIn, reserveOut);}function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut)publicpurevirtualoverridereturns (uint amountIn){return UniswapV2Library.getAmountIn(amountOut, reserveIn, reserveOut);}function getAmountsOut(uint amountIn, address[] memory path)publicviewvirtualoverridereturns (uint[] memory amounts){return UniswapV2Library.getAmountsOut(factory, amountIn, path);}function getAmountsIn(uint amountOut, address[] memory path)publicviewvirtualoverridereturns (uint[] memory amounts){return UniswapV2Library.getAmountsIn(factory, amountOut, path);}
}// a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)library SafeMath {function add(uint x, uint y) internal pure returns (uint z) {require((z = x + y) >= x, 'ds-math-add-overflow');}function sub(uint x, uint y) internal pure returns (uint z) {require((z = x - y) <= x, 'ds-math-sub-underflow');}function mul(uint x, uint y) internal pure returns (uint z) {require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');}
}library UniswapV2Library {using SafeMath for uint;// returns sorted token addresses, used to handle return values from pairs sorted in this order//两个token排序，address实际也是一个uint160，可以相关转换，所以可以比大小，排序,小是0，确认在交易对中的token0,token1function sortTokens(address tokenA, address tokenB) internal pure returns (address token0, address token1) {require(tokenA != tokenB, 'UniswapV2Library: IDENTICAL_ADDRESSES');(token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);require(token0 != address(0), 'UniswapV2Library: ZERO_ADDRESS');}// calculates the CREATE2 address for a pair without making any external calls// 通过create2的方式计算交易对的地址，注意initCode,每次部署的时候，可能都不一样，需要生成//用法套格式即可，对应factory中的createPair， 要深入的，可以具体去了解下create2function pairFor(address factory, address tokenA, address tokenB) internal pure returns (address pair) {(address token0, address token1) = sortTokens(tokenA, tokenB);pair = address(uint(keccak256(abi.encodePacked(hex'ff',factory,keccak256(abi.encodePacked(token0, token1)),hex'96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f' // init code hash))));}// fetches and sorts the reserves for a pair//获取两个币的储备量， 通过pair查询， 内部返回值会根据入参的币种进行调整位置返回function getReserves(address factory, address tokenA, address tokenB) internal view returns (uint reserveA, uint reserveB) {(address token0,) = sortTokens(tokenA, tokenB);(uint reserve0, uint reserve1,) = IUniswapV2Pair(pairFor(factory, tokenA, tokenB)).getReserves();(reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);}// given some amount of an asset and pair reserves, returns an equivalent amount of the other asset// 添加流动性的时候，通过该方法查询输入A的数量，需要多少个Bfunction quote(uint amountA, uint reserveA, uint reserveB) internal pure returns (uint amountB) {//判断数量， 首次添加流动性，随意定价，不需要查询该方法require(amountA > 0, 'UniswapV2Library: INSUFFICIENT_AMOUNT');require(reserveA > 0 && reserveB > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');//B数量 = 预期输入A的数量 * B的储备量 / A的储备量；  //实际公式就是 A/B = reserveA/reserveB, 两个币的数量比例一致amountB = amountA.mul(reserveB) / reserveA;}// given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset//通过精确输入金额,输入币的储备量，输出币的储备量，计算输出币的最大输出量function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) internal pure returns (uint amountOut) {require(amountIn > 0, 'UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT');require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');//具体看下面的公式推导，要看该公式，首先要理解uniswap AMM, X * Y= Kuint amountInWithFee = amountIn.mul(997);//手续费都是扣输入额的千三，所以需要去掉千三后才是实际用于交易的金额uint numerator = amountInWithFee.mul(reserveOut);//套下面公式理解吧！！uint denominator = reserveIn.mul(1000).add(amountInWithFee);amountOut = numerator / denominator;/**   查看下面的由in计算out公式 out = in * f * rOut / rIn + in *f*   手续费是千三， 扣除手续费后去交易的金额是输入额的0.997, 公式中的f是0.997 内部计算用的uint,所以分子分母都 * 1000*   最终的公式是    out = in * 997 * rOut / ((rIn + in *f) * 1000)*                  out = in * 997 * rOut / (rIn*1000 + in * 997)*/}/***** 推导公式* in 输入金额， out 输出金额* rIn tokenIn的流动性， rOut，tokenOut的流动性* fee 手续费，注：当前带入0.997   也就是997/1000** 两个计算公式实际是一样的， 只是一个求in,一个求out* (rIn + in * f) * (rOut - out) = rIn * rOut*** 由out计算in  getAmountIn* (rIn + in * f) * (rOut - out) = rIn * rOut* rIn * rOut + in * f * rOut  - rIn * out - in * f * out = rIn * rOut* rIn * out = in * f * rOut - in * f * out* in = rIn * out / (f * (rOut - out)) + 1  (尾部的 +1应该是避免精度计算，最后一位小了，会成交不了)*** 由in计算out  getAmountOut* (rIn + in * f) * (rOut - out) = rIn * rOut* rIn * rOut + in * f * rOut  - rIn * out - in * f * out = rIn * rOut* in * f * rOut = rIn * out + in * f * out* out = in * f * rOut / rIn + in *f**/// given an output amount of an asset and pair reserves, returns a required input amount of the other asset//通过精确的输出量，输入币的储备量，输出币的储备量，计算所需的输入币的数量function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) internal pure returns (uint amountIn) {require(amountOut > 0, 'UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT');require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');//先看上面的由out计算in 公式推导uint numerator = reserveIn.mul(amountOut).mul(1000);//对应公式中的rIn * out, 乘以1000是0.997需要换算成整数uint denominator = reserveOut.sub(amountOut).mul(997);//对应上面的分母 (f * (rOut - out)),乘以1000后就是 997 * (rOut - out)amountIn = (numerator / denominator).add(1);}// performs chained getAmountOut calculations on any number of pairs// 根据path,计算出每个交易对的输入/输出量(如果path>2,前一个交易对的输出量，就是下一个交易对交易的输入量)//内部实际还是调用的上面getAmountOut方法， 返回值amounts长度和path的长度一致，function getAmountsOut(address factory, uint amountIn, address[] memory path) internal view returns (uint[] memory amounts) {require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');amounts = new uint[](path.length);//创建数组amounts[0] = amountIn;//0位置是输入量for (uint i; i < path.length - 1; i++) {//每两个token组成一个交易对，计算out(uint reserveIn, uint reserveOut) = getReserves(factory, path[i], path[i + 1]);amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);}}// performs chained getAmountIn calculations on any number of pairs// 根据path,计算出每个交易对的输入/输出量(如果path>2,前一个交易对的输出量，就是下一个交易对交易的输入量)//内部实际还是调用的上面getAmountIn方法， 返回值amounts长度和path的长度一致，function getAmountsIn(address factory, uint amountOut, address[] memory path) internal view returns (uint[] memory amounts) {require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');amounts = new uint[](path.length);amounts[amounts.length - 1] = amountOut;//最后一个是入参out,for (uint i = path.length - 1; i > 0; i--) {//倒序遍历计算(uint reserveIn, uint reserveOut) = getReserves(factory, path[i - 1], path[i]);amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);}}
}// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
//转账工具类
library TransferHelper {function safeApprove(address token, address to, uint value) internal {// bytes4(keccak256(bytes('approve(address,uint256)')));(bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: APPROVE_FAILED');}//注：data.length == 0,主要针对的是usdt, 同时！该方法在波场不适用！！ 波场的的U 有返回data,但是一直是false!!function safeTransfer(address token, address to, uint value) internal {// bytes4(keccak256(bytes('transfer(address,uint256)')));(bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FAILED');}function safeTransferFrom(address token, address from, address to, uint value) internal {// bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));(bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FROM_FAILED');}function safeTransferETH(address to, uint value) internal {(bool success,) = to.call{value : value}(new bytes(0));require(success, 'TransferHelper: ETH_TRANSFER_FAILED');}
}

uniswap 闪电贷(待补充)

uniswap 添加/移除lp时手续费公式(待补充)

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uniswap v2 代码解读注释

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UniswapV2Factory

UniswapV2Router02

uniswap 闪电贷(待补充)

uniswap 添加/移除lp时手续费公式(待补充)

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