秒合约系统部分源码参考 秒合约系统逻辑实现，

The blockchain mall creates a perfect integration platform ofconsumer shopping and blockchain technology,so that the advantagesof blockchain technology can serve the actual transaction scenarioof consumer shopping and help consumers realize the dream ofvalue-added shopping.The model first uses the blockchain mallplatform to leverage the trend 系统-176搭建-0206+可电可 blockchaintechnology to help physical enterprises rapidly increase productsales,and at the same time,it also allows consumers to obtainsubstantial benefits in shopping.
　　
　　pragma solidity>=0.5.0;
　　
　　import'uniswap/v2-core/contracts/interfaces/IUniswapV2Pair.sol';
　　
　　import"./SafeMath.sol";
　　
　　library UniswapV2Library{
　　
　　using SafeMath for uint;
　　
　　//returns sorted token addresses,used to handle return valuesfrom pairs sorted in this order
　　
　　function sortTokens(address tokenA,address tokenB)internal purereturns(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 anyexternal calls
　　
　　// 在不进行任何外部调用的情况下计算一对的 CREATE2 地址
　　
　　function pairFor(address factory,address tokenA,addresstokenB)internal pure returns(address pair){
　　
　　(address token0,addresstoken1)=sortTokens(tokenA,tokenB);