Smart contracts are fully functional,flexible and controllable programs that can be invoked on distributed ledgers,with the advantages of transparency,trustworthiness,automatic execution,and mandatory performance.When it is deployed to a distributed ledger,the code of the program is transparent.

　　大公排指的是全網(wǎng)排列，小公排指的是單體傘下排列，一條線公排指的是按一條線排列，跳排指的按指定某代數(shù)為推薦關(guān)系。

　　大公排和小公排常見的排網(wǎng)方式是自上而下自左至右。

　　公排模式中常見的案例有雙軌二二復制，三軌三三復制，五五復制、太陽線等。

　　pragma solidity=0.5.16;

　　import'./interfaces/IUniswapV2Pair.sol';

　　import'./UniswapV2ERC20.sol';

　　import'./libraries/Math.sol';

　　import'./libraries/UQ112x112.sol';

　　import'./interfaces/IERC20.sol';

　　import'./interfaces/IUniswapV2Factory.sol';

　　import'./interfaces/IUniswapV2Callee.sol';

　　contract UniswapV2Pair is IUniswapV2Pair,UniswapV2ERC20{

　　using SafeMath for uint;

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　　using UQ112x112 for uint224;

　　uint public constant MINIMUM_LIQUIDITY=10**3;

　　bytes4 private constant SELECTOR=bytes4(keccak256(bytes('transfer(address,uint256)')));

　　address public factory;開發(fā)邏輯I59詳細2OO7模式3O69

　　address public token0;

　　address public token1;

　　uint112 private reserve0;//uses single storage slot,accessible via getReserves

　　uint112 private reserve1;//uses single storage slot,accessible via getReserves

　　uint32 private blockTimestampLast;//uses single storage slot,accessible via getReserves

　　uint public price0CumulativeLast;

　　uint public price1CumulativeLast;

　　uint public kLast;//reserve0*reserve1,as of immediately after the most recent liquidity event

　　uint private unlocked=1;

　　modifier lock(){

　　require(unlocked==1,'UniswapV2:LOCKED');

　　unlocked=0;

　　_;

　　unlocked=1;

　　}

　　function getReserves()public view returns(uint112 _reserve0,uint112 _reserve1,uint32 _blockTimestampLast){

　　_reserve0=reserve0;

　　_reserve1=reserve1;

　　_blockTimestampLast=blockTimestampLast;

　　}

　　function _safeTransfer(address token,address to,uint value)private{

　　(bool success,bytes memory data)=token.call(abi.encodeWithSelector(SELECTOR,to,value));

　　require(success&&(data.length==0||abi.decode(data,(bool))),'UniswapV2:TRANSFER_FAILED');

　　}

　　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);

　　constructor()public{

　　factory=msg.sender;

　　}

　　//called once by the factory at time of deployment

　　function initialize(address _token0,address _token1)external{

　　require(msg.sender==factory,'UniswapV2:FORBIDDEN');//sufficient check

　　token0=_token0;

　　token1=_token1;

　　}

　　//update reserves and,on the first call per block,price accumulators

　　function _update(uint balance0,uint balance1,uint112 _reserve0,uint112 _reserve1)private{

　　require(balance0<=uint112(-1)&&balance1<=uint112(-1),'UniswapV2:OVERFLOW');

　　uint32 blockTimestamp=uint32(block.timestamp%2**32);

　　uint32 timeElapsed=blockTimestamp-blockTimestampLast;//overflow is desired

　　if(timeElapsed>0&&_reserve0!=0&&_reserve1!=0){

　　//*never overflows,and+overflow is desired

　　price0CumulativeLast+=uint(UQ112x112.encode(_reserve1).uqdiv(_reserve0))*timeElapsed;

　　price1CumulativeLast+=uint(UQ112x112.encode(_reserve0).uqdiv(_reserve1))*timeElapsed;

　　}

　　reserve0=uint112(balance0);

　　reserve1=uint112(balance1);

　　blockTimestampLast=blockTimestamp;

　　emit Sync(reserve0,reserve1);

　　}