Ptahdao智能合约流动性质押挖矿系统开发技术详细丨（源码案例）

　　智能合约dapp开发技术主要由以太坊区块链网络提供支持，该网络提供了一系列的智能合约技术，这些智能合约可以让开发者快速、安全地构建出功能强大的dapp。智能合约dapp开发技术主要包括以太坊智能合约语言Solidity，以太坊智能合约框架Truffle，Web3.js，以太坊区块链浏览器Mist等

　　智能合约：它们是存储在区块链上的计算机程序，在满足预定条件时运行，智能合约是用Solidity语言编写的。

　　web3.js是一个JavaScript API库。要让DApp在以太坊上运行，我们可以使用web3.js库提供的web3对象。web3.js通过RPC调用与本地节点通信，详细唯：MrsFu123 它可以与任何公开RPC层的以太坊节点一起使用。web3包含eth对象-web3.eth（用于与以太坊区块链交互）和shh对象-web3.shh（用于与Whisper交互）

　　//this low-level function should be called from a contract which performs important safety checks

　　function burn(address to)external lock returns(uint amount0,uint amount1){

　　(uint112 _reserve0,uint112 _reserve1,)=getReserves();//gas savings

　　address _token0=token0;//gas savings

　　address _token1=token1;//gas savings

　　uint balance0=IERC20(_token0).balanceOf(address(this));

         开发功能I35详情7O98系统O7I8

　　uint balance1=IERC20(_token1).balanceOf(address(this));

　　uint liquidity=balanceOf[address(this)];

　　bool feeOn=_mintFee(_reserve0,_reserve1);

　　uint _totalSupply=totalSupply;//gas savings,must be defined here since totalSupply can update in _mintFee

　　amount0=liquidity.mul(balance0)/_totalSupply;//using balances ensures pro-rata distribution

　　amount1=liquidity.mul(balance1)/_totalSupply;//using balances ensures pro-rata distribution

　　require(amount0>0&&amount1>0,'UniswapV2:INSUFFICIENT_LIQUIDITY_BURNED');

　　_burn(address(this),liquidity);

　　_safeTransfer(_token0,to,amount0);

　　_safeTransfer(_token1,to,amount1);

　　balance0=IERC20(_token0).balanceOf(address(this));

　　balance1=IERC20(_token1).balanceOf(address(this));

　　_update(balance0,balance1,_reserve0,_reserve1);

　　if(feeOn)kLast=uint(reserve0).mul(reserve1);//reserve0 and reserve1 are up-to-date

　　emit Burn(msg.sender,amount0,amount1,to);

　　}

　　//this low-level function should be called from a contract which performs important safety checks

　　function swap(uint amount0Out,uint amount1Out,address to,bytes calldata data)external lock{

　　require(amount0Out>0||amount1Out>0,'UniswapV2:INSUFFICIENT_OUTPUT_AMOUNT');

　　(uint112 _reserve0,uint112 _reserve1,)=getReserves();//gas savings

　　require(amount0Out<_reserve0&&amount1Out<_reserve1,'UniswapV2:INSUFFICIENT_LIQUIDITY');

　　uint balance0;

　　uint balance1;

　　{//scope for _token{0,1},avoids stack too deep errors

　　address _token0=token0;

　　address _token1=token1;

　　require(to!=_token0&&to!=_token1,'UniswapV2:INVALID_TO');

　　if(amount0Out>0)_safeTransfer(_token0,to,amount0Out);//optimistically transfer tokens

　　if(amount1Out>0)_safeTransfer(_token1,to,amount1Out);//optimistically transfer tokens

　　if(data.length>0)IUniswapV2Callee(to).uniswapV2Call(msg.sender,amount0Out,amount1Out,data);

　　balance0=IERC20(_token0).balanceOf(address(this));

　　balance1=IERC20(_token1).balanceOf(address(this));

　　}

　　uint amount0In=balance0>_reserve0-amount0Out?balance0-(_reserve0-amount0Out):0;

　　uint amount1In=balance1>_reserve1-amount1Out?balance1-(_reserve1-amount1Out):0;

　　require(amount0In>0||amount1In>0,'UniswapV2:INSUFFICIENT_INPUT_AMOUNT');

　　{//scope for reserve{0,1}Adjusted,avoids stack too deep errors

　　uint balance0Adjusted=balance0.mul(1000).sub(amount0In.mul(3));

　　uint balance1Adjusted=balance1.mul(1000).sub(amount1In.mul(3));

　　require(balance0Adjusted.mul(balance1Adjusted)>=uint(_reserve0).mul(_reserve1).mul(1000**2),'UniswapV2:K');

　　}

　　_update(balance0,balance1,_reserve0,_reserve1);

　　emit Swap(msg.sender,amount0In,amount1In,amount0Out,amount1Out,to);

　　}

　　//force balances to match reserves

　　function skim(address to)external lock{

　　address _token0=token0;//gas savings

　　address _token1=token1;//gas savings

　　_safeTransfer(_token0,to,IERC20(_token0).balanceOf(address(this)).sub(reserve0));

　　_safeTransfer(_token1,to,IERC20(_token1).balanceOf(address(this)).sub(reserve1));

　　}

　　//force reserves to match balances

　　function sync()external lock{

　　_update(IERC20(token0).balanceOf(address(this)),IERC20(token1).balanceOf(address(this)),reserve0,reserve1);

　　}

　　}