币安BSC智能链发币教程——通过对标代币余额来区分买入和撤销流动性，卖出和添加流动性的区别，进而设置不同的交易手续费【pdf+视频BSC发币教程下载】

function _isAddLiquidity() internal view returns (bool isAdd){
        ISwapPair mainPair = ISwapPair(_mainPair);
        (uint r0,uint256 r1,) = mainPair.getReserves();

        //add Liquidity logic
    }

2. 判断撤销流动性函数

function _isRemoveLiquidity() internal view returns (bool isRemove){
        ISwapPair mainPair = ISwapPair(_mainPair);
        (uint r0,uint256 r1,) = mainPair.getReserves();

        //remove liquidity logic
    }

3. 加池，撤池，买入，卖出，转账分别设置不同的手续费实现代码

function _tokenTransfer(
        address sender,
        address recipient,
        uint256 tAmount,
        bool takeFee,
        bool isRemoveLP,
        bool isAddLP
    ) private {
        _balances[sender] = _balances[sender] - tAmount;
        uint256 feeAmount;

        if (takeFee) {
            if (isRemoveLP) {
                feeAmount = tAmount * _removeLPFee / 10000;
                if (feeAmount > 0) {
                    _takeTransfer(sender, fundAddress, feeAmount);
                }
            } else if (isAddLP) {
                feeAmount = tAmount * _addLPFee / 10000;
                if (feeAmount > 0) {
                    _takeTransfer(sender, fundAddress, feeAmount);
                }
            } else if (_swapPairList[sender]) {//Buy
                uint256 fundAmount = tAmount * (_buyFundFee + _buyFundFee2 + _buyFundFee3 + _buyLPDividendFee + _buyLPFee) / 10000;
                if (fundAmount > 0) {
                    feeAmount += fundAmount;
                    _takeTransfer(sender, address(this), fundAmount);
                }
            } else if (_swapPairList[recipient]) {//Sell
                uint256 fundAmount = tAmount * (_sellFundFee + _sellFundFee2 + _sellFundFee3 + _sellLPDividendFee + _sellLPFee) / 10000;
                if (fundAmount > 0) {
                    feeAmount += fundAmount;
                    _takeTransfer(sender, address(this), fundAmount);
                }

                if (!inSwap) {
                    uint256 contractTokenBalance = balanceOf(address(this));
                    if (contractTokenBalance > 0) {
                        uint256 numTokensSellToFund = fundAmount * 230 / 100;
                        if (numTokensSellToFund > contractTokenBalance) {
                            numTokensSellToFund = contractTokenBalance;
                        }
                        swapTokenForFund(numTokensSellToFund);
                    }
                }
            } else {//Transfer
                feeAmount = tAmount * _transferFee / 10000;
                if (feeAmount > 0) {
                    _takeTransfer(sender, fundAddress, feeAmount);
                }
            }
        }
        _takeTransfer(sender, recipient, tAmount - feeAmount);
    }

至此，完成通过对标代币余额来区分买入和撤销流动性，卖出和添加流动性的区别，进而设置不同的交易手续费所有操作流程。

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