Uniswap-v2 合約逐步詳解

1pragma solidity =0.5.16;
2
3import './interfaces/IUniswapV2Pair.sol';
4import './UniswapV2ERC20.sol';
5import './libraries/Math.sol';
6import './libraries/UQ112x112.sol';
7import './interfaces/IERC20.sol';
8import './interfaces/IUniswapV2Factory.sol';
9import './interfaces/IUniswapV2Callee.sol';
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1contract UniswapV2Pair is IUniswapV2Pair, UniswapV2ERC20 {
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1    using SafeMath  for uint;
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1    using UQ112x112 for uint224;
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1    uint public constant MINIMUM_LIQUIDITY = 10**3;
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1    bytes4 private constant SELECTOR = bytes4(keccak256(bytes('transfer(address,uint256)')));
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1    address public factory;
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1    address public token0;
2    address public token1;
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1    uint112 private reserve0;           // 使用單一儲存槽，可透過 getReserves 存取
2    uint112 private reserve1;           // 使用單一儲存槽，可透過 getReserves 存取
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1    uint32  private blockTimestampLast; // 使用單一儲存槽，可透過 getReserves 存取
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1    uint public price0CumulativeLast;
2    uint public price1CumulativeLast;
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1    uint public kLast; // reserve0 * reserve1，截至最近一次流動性事件發生後
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1    uint private unlocked = 1;
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1    modifier lock() {
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1        require(unlocked == 1, 'UniswapV2: LOCKED');
2        unlocked = 0;
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1        _;
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1        unlocked = 1;
2    }
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1    function getReserves() public view returns (uint112 _reserve0, uint112 _reserve1, uint32 _blockTimestampLast) {
2        _reserve0 = reserve0;
3        _reserve1 = reserve1;
4        _blockTimestampLast = blockTimestampLast;
5    }
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1    function _safeTransfer(address token, address to, uint value) private {
2        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(SELECTOR, to, value));
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1        require(success && (data.length == 0 || abi.decode(data, (bool))), 'UniswapV2: TRANSFER_FAILED');
2    }
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1    event Mint(address indexed sender, uint amount0, uint amount1);
2    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
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1    event Swap(
2        address indexed sender,
3        uint amount0In,
4        uint amount1In,
5        uint amount0Out,
6        uint amount1Out,
7        address indexed to
8    );
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1    event Sync(uint112 reserve0, uint112 reserve1);
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1    constructor() public {
2        factory = msg.sender;
3    }
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1    // 在部署時由工廠呼叫一次
2    function initialize(address _token0, address _token1) external {
3        require(msg.sender == factory, 'UniswapV2: FORBIDDEN'); // 充分的檢查
4        token0 = _token0;
5        token1 = _token1;
6    }
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1    // 更新儲備金，以及在每個區塊的第一次呼叫時更新價格累加器
2    function _update(uint balance0, uint balance1, uint112 _reserve0, uint112 _reserve1) private {
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1        require(balance0 <= uint112(-1) && balance1 <= uint112(-1), 'UniswapV2: OVERFLOW');
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1        uint32 blockTimestamp = uint32(block.timestamp % 2**32);
2        uint32 timeElapsed = blockTimestamp - blockTimestampLast; // 期望溢位
3        if (timeElapsed > 0 && _reserve0 != 0 && _reserve1 != 0) {
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1            // * 永不溢位，而 + 期望溢位
2            price0CumulativeLast += uint(UQ112x112.encode(_reserve1).uqdiv(_reserve0)) * timeElapsed;
3            price1CumulativeLast += uint(UQ112x112.encode(_reserve0).uqdiv(_reserve1)) * timeElapsed;
4        }
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1        reserve0 = uint112(balance0);
2        reserve1 = uint112(balance1);
3        blockTimestampLast = blockTimestamp;
4        emit Sync(reserve0, reserve1);
5    }
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1    // 如果費用開啟，則鑄造相當於 sqrt(k) 增長量 1/6 的流動性
2    function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
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1        address feeTo = IUniswapV2Factory(factory).feeTo();
2        feeOn = feeTo != address(0);
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1        uint _kLast = kLast; // 節省 gas
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1        if (feeOn) {
2            if (_kLast != 0) {
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1                uint rootK = Math.sqrt(uint(_reserve0).mul(_reserve1));
2                uint rootKLast = Math.sqrt(_kLast);
3                if (rootK > rootKLast) {
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1                    uint numerator = totalSupply.mul(rootK.sub(rootKLast));
2                    uint denominator = rootK.mul(5).add(rootKLast);
3                    uint liquidity = numerator / denominator;
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1                    if (liquidity > 0) _mint(feeTo, liquidity);
2                }
3            }
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1        } else if (_kLast != 0) {
2            kLast = 0;
3        }
4    }
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1    // 這個低階函式應由執行重要安全檢查的合約呼叫
2    function mint(address to) external lock returns (uint liquidity) {
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1        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // 節省 gas
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1        uint balance0 = IERC20(token0).balanceOf(address(this));
2        uint balance1 = IERC20(token1).balanceOf(address(this));
3        uint amount0 = balance0.sub(_reserve0);
4        uint amount1 = balance1.sub(_reserve1);
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1        bool feeOn = _mintFee(_reserve0, _reserve1);
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1        uint _totalSupply = totalSupply; // 節省 gas，必須在此處定義，因為 totalSupply 可能在 _mintFee 中更新
2        if (_totalSupply == 0) {
3            liquidity = Math.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
4           _mint(address(0), MINIMUM_LIQUIDITY); // 永久鎖定最初的 MINIMUM_LIQUIDITY 代幣
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1        } else {
2            liquidity = Math.min(amount0.mul(_totalSupply) / _reserve0, amount1.mul(_totalSupply) / _reserve1);
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1        }
2        require(liquidity > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_MINTED');
3        _mint(to, liquidity);
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1
2        _update(balance0, balance1, _reserve0, _reserve1);
3        if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 和 reserve1 是最新的
4        emit Mint(msg.sender, amount0, amount1);
5    }
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1    // 這個低階函式應由執行重要安全檢查的合約呼叫
2    function burn(address to) external lock returns (uint amount0, uint amount1) {
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1        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // 節省 gas
2        address _token0 = token0;                                // 節省 gas
3        address _token1 = token1;                                // 節省 gas
4        uint balance0 = IERC20(_token0).balanceOf(address(this));
5        uint balance1 = IERC20(_token1).balanceOf(address(this));
6        uint liquidity = balanceOf[address(this)];
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1        bool feeOn = _mintFee(_reserve0, _reserve1);
2        uint _totalSupply = totalSupply; // 節省 gas，必須在此處定義，因為 totalSupply 可能在 _mintFee 中更新
3        amount0 = liquidity.mul(balance0) / _totalSupply; // 使用餘額確保按比例分配
4        amount1 = liquidity.mul(balance1) / _totalSupply; // 使用餘額確保按比例分配
5        require(amount0 > 0 && amount1 > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_BURNED');
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1        _burn(address(this), liquidity);
2        _safeTransfer(_token0, to, amount0);
3        _safeTransfer(_token1, to, amount1);
4        balance0 = IERC20(_token0).balanceOf(address(this));
5        balance1 = IERC20(_token1).balanceOf(address(this));
6
7        _update(balance0, balance1, _reserve0, _reserve1);
8        if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 和 reserve1 是最新的
9        emit Burn(msg.sender, amount0, amount1, to);
10    }
11
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1    // 這個低階函式應由執行重要安全檢查的合約呼叫
2    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external lock {
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1        require(amount0Out > 0 || amount1Out > 0, 'UniswapV2: INSUFFICIENT_OUTPUT_AMOUNT');
2        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // 節省 gas
3        require(amount0Out < _reserve0 && amount1Out < _reserve1, 'UniswapV2: INSUFFICIENT_LIQUIDITY');
4
5        uint balance0;
6        uint balance1;
7        { // _token{0,1} 的作用域，避免堆疊太深錯誤
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1            address _token0 = token0;
2            address _token1 = token1;
3            require(to != _token0 && to != _token1, 'UniswapV2: INVALID_TO');
4            if (amount0Out > 0) _safeTransfer(_token0, to, amount0Out); // 樂觀地轉移代幣
5            if (amount1Out > 0) _safeTransfer(_token1, to, amount1Out); // 樂觀地轉移代幣
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1            if (data.length > 0) IUniswapV2Callee(to).uniswapV2Call(msg.sender, amount0Out, amount1Out, data);
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1            balance0 = IERC20(_token0).balanceOf(address(this));
2            balance1 = IERC20(_token1).balanceOf(address(this));
3        }
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1        uint amount0In = balance0 > _reserve0 - amount0Out ? balance0 - (_reserve0 - amount0Out) : 0;
2        uint amount1In = balance1 > _reserve1 - amount1Out ? balance1 - (_reserve1 - amount1Out) : 0;
3        require(amount0In > 0 || amount1In > 0, 'UniswapV2: INSUFFICIENT_INPUT_AMOUNT');
4        { // reserve{0,1}Adjusted 的作用域，避免堆疊太深錯誤
5            uint balance0Adjusted = balance0.mul(1000).sub(amount0In.mul(3));
6            uint balance1Adjusted = balance1.mul(1000).sub(amount1In.mul(3));
7            require(balance0Adjusted.mul(balance1Adjusted) >= uint(_reserve0).mul(_reserve1).mul(1000**2), 'UniswapV2: K');
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1        }
2
3        _update(balance0, balance1, _reserve0, _reserve1);
4        emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to);
5    }
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1    // 強制餘額與儲備金匹配
2    function skim(address to) external lock {
3        address _token0 = token0; // 節省 gas
4        address _token1 = token1; // 節省 gas
5        _safeTransfer(_token0, to, IERC20(_token0).balanceOf(address(this)).sub(reserve0));
6        _safeTransfer(_token1, to, IERC20(_token1).balanceOf(address(this)).sub(reserve1));
7    }
8
9
10
11    // 強制儲備金與餘額匹配
12    function sync() external lock {
13        _update(IERC20(token0).balanceOf(address(this)), IERC20(token1).balanceOf(address(this)), reserve0, reserve1);
14    }
15}
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1pragma solidity =0.5.16;
2
3import './interfaces/IUniswapV2Factory.sol';
4import './UniswapV2Pair.sol';
5
6contract UniswapV2Factory is IUniswapV2Factory {
7    address public feeTo;
8    address public feeToSetter;
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1    mapping(address => mapping(address => address)) public getPair;
2    address[] public allPairs;
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1    event PairCreated(address indexed token0, address indexed token1, address pair, uint);
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1    constructor(address _feeToSetter) public {
2        feeToSetter = _feeToSetter;
3    }
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1    function allPairsLength() external view returns (uint) {
2        return allPairs.length;
3    }
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1    function createPair(address tokenA, address tokenB) external returns (address pair) {
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1        require(tokenA != tokenB, 'UniswapV2: IDENTICAL_ADDRESSES');
2        (address token0, address token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
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1        require(token0 != address(0), 'UniswapV2: ZERO_ADDRESS');
2        require(getPair[token0][token1] == address(0), 'UniswapV2: PAIR_EXISTS'); // 單一檢查即足夠
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1        bytes memory bytecode = type(UniswapV2Pair).creationCode;
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1        bytes32 salt = keccak256(abi.encodePacked(token0, token1));
2        assembly {
3            pair := create2(0, add(bytecode, 32), mload(bytecode), salt)
4        }
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1        IUniswapV2Pair(pair).initialize(token0, token1);
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1        getPair[token0][token1] = pair;
2        getPair[token1][token0] = pair; // 以相反方向填入對應
3        allPairs.push(pair);
4        emit PairCreated(token0, token1, pair, allPairs.length);
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1    function setFeeTo(address _feeTo) external {
2        require(msg.sender == feeToSetter, 'UniswapV2: FORBIDDEN');
3        feeTo = _feeTo;
4    }
5
6    function setFeeToSetter(address _feeToSetter) external {
7        require(msg.sender == feeToSetter, 'UniswapV2: FORBIDDEN');
8        feeToSetter = _feeToSetter;
9    }
10}
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1    bytes32 public DOMAIN_SEPARATOR;
2    // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
3    bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
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1    mapping(address => uint) public nonces;
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1    constructor() public {
2        uint chainId;
3        assembly {
4            chainId := chainid
5        }
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1        DOMAIN_SEPARATOR = keccak256(
2            abi.encode(
3                keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
4                keccak256(bytes(name)),
5                keccak256(bytes('1')),
6                chainId,
7                address(this)
8            )
9        );
10    }
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1    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
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1        require(deadline >= block.timestamp, 'UniswapV2: EXPIRED');
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1        bytes32 digest = keccak256(
2            abi.encodePacked(
3                '\x19\x01',
4                DOMAIN_SEPARATOR,
5                keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
6            )
7        );
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1        address recoveredAddress = ecrecover(digest, v, r, s);
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1        require(recoveredAddress != address(0) && recoveredAddress == owner, 'UniswapV2: INVALID_SIGNATURE');
2        _approve(owner, spender, value);
3    }
4
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1pragma solidity =0.6.6;
2
3import '@uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol';
4import '@uniswap/lib/contracts/libraries/TransferHelper.sol';
5
6import './interfaces/IUniswapV2Router02.sol';
7import './libraries/UniswapV2Library.sol';
8import './libraries/SafeMath.sol';
9import './interfaces/IERC20.sol';
10import './interfaces/IWETH.sol';
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1contract UniswapV2Router02 is IUniswapV2Router02 {
2    using SafeMath for uint;
3
4    address public immutable override factory;
5    address public immutable override WETH;
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1    modifier ensure(uint deadline) {
2        require(deadline >= block.timestamp, 'UniswapV2Router: EXPIRED');
3        _;
4    }
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1    constructor(address _factory, address _WETH) public {
2        factory = _factory;
3        WETH = _WETH;
4    }
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1    receive() external payable {
2        assert(msg.sender == WETH); // 只接受透過 WETH 合約的回退函式傳入的 ETH
3    }
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1
2    // **** 增加流動性 ****
3    function _addLiquidity(
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1        address tokenA,
2        address tokenB,
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1        uint amountADesired,
2        uint amountBDesired,
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1        uint amountAMin,
2        uint amountBMin
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1    ) internal virtual returns (uint amountA, uint amountB) {
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1        // 如果交易對尚不存在，則建立它
2        if (IUniswapV2Factory(factory).getPair(tokenA, tokenB) == address(0)) {
3            IUniswapV2Factory(factory).createPair(tokenA, tokenB);
4        }
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1        (uint reserveA, uint reserveB) = UniswapV2Library.getReserves(factory, tokenA, tokenB);
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1        if (reserveA == 0 && reserveB == 0) {
2            (amountA, amountB) = (amountADesired, amountBDesired);
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1        } else {
2            uint amountBOptimal = UniswapV2Library.quote(amountADesired, reserveA, reserveB);
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1            if (amountBOptimal <= amountBDesired) {
2                require(amountBOptimal >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');
3                (amountA, amountB) = (amountADesired, amountBOptimal);
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1            } else {
2                uint amountAOptimal = UniswapV2Library.quote(amountBDesired, reserveB, reserveA);
3                assert(amountAOptimal <= amountADesired);
4                require(amountAOptimal >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
5                (amountA, amountB) = (amountAOptimal, amountBDesired);
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1    function addLiquidity(
2        address tokenA,
3        address tokenB,
4        uint amountADesired,
5        uint amountBDesired,
6        uint amountAMin,
7        uint amountBMin,
8        address to,
9        uint deadline
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1    ) external virtual override ensure(deadline) returns (uint amountA, uint amountB, uint liquidity) {
2        (amountA, amountB) = _addLiquidity(tokenA, tokenB, amountADesired, amountBDesired, amountAMin, amountBMin);
3        address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
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1        TransferHelper.safeTransferFrom(tokenA, msg.sender, pair, amountA);
2        TransferHelper.safeTransferFrom(tokenB, msg.sender, pair, amountB);
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1        liquidity = IUniswapV2Pair(pair).mint(to);
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1    function addLiquidityETH(
2        address token,
3        uint amountTokenDesired,
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1        uint amountTokenMin,
2        uint amountETHMin,
3        address to,
4        uint deadline
5    ) external virtual override payable ensure(deadline) returns (uint amountToken, uint amountETH, uint liquidity) {
6        (amountToken, amountETH) = _addLiquidity(
7            token,
8            WETH,
9            amountTokenDesired,
10            msg.value,
11            amountTokenMin,
12            amountETHMin
13        );
14        address pair = UniswapV2Library.pairFor(factory, token, WETH);
15        TransferHelper.safeTransferFrom(token, msg.sender, pair, amountToken);
16        IWETH(WETH).deposit{value: amountETH}();
17        assert(IWETH(WETH).transfer(pair, amountETH));
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1        liquidity = IUniswapV2Pair(pair).mint(to);
2        // refund dust eth, if any
3        if (msg.value > amountETH) TransferHelper.safeTransferETH(msg.sender, msg.value - amountETH);
4    }
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1    // **** 移除流動性 ****
2    function removeLiquidity(
3        address tokenA,
4        address tokenB,
5        uint liquidity,
6        uint amountAMin,
7        uint amountBMin,
8        address to,
9        uint deadline
10    ) public virtual override ensure(deadline) returns (uint amountA, uint amountB) {
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1        address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
2        IUniswapV2Pair(pair).transferFrom(msg.sender, pair, liquidity); // 將流動性發送到交易對
3        (uint amount0, uint amount1) = IUniswapV2Pair(pair).burn(to);
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1        (address token0,) = UniswapV2Library.sortTokens(tokenA, tokenB);
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1        (amountA, amountB) = tokenA == token0 ? (amount0, amount1) : (amount1, amount0);
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1        require(amountA >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
2        require(amountB >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');
3    }
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1    function removeLiquidityETH(
2        address token,
3        uint liquidity,
4        uint amountTokenMin,
5        uint amountETHMin,
6        address to,
7        uint deadline
8    ) public virtual override ensure(deadline) returns (uint amountToken, uint amountETH) {
9        (amountToken, amountETH) = removeLiquidity(
10            token,
11            WETH,
12            liquidity,
13            amountTokenMin,
14            amountETHMin,
15            address(this),
16            deadline
17        );
18        TransferHelper.safeTransfer(token, to, amountToken);
19        IWETH(WETH).withdraw(amountETH);
20        TransferHelper.safeTransferETH(to, amountETH);
21    }
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1    function removeLiquidityWithPermit(
2        address tokenA,
3        address tokenB,
4        uint liquidity,
5        uint amountAMin,
6        uint amountBMin,
7        address to,
8        uint deadline,
9        bool approveMax, uint8 v, bytes32 r, bytes32 s
10    ) external virtual override returns (uint amountA, uint amountB) {
11        address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
12        uint value = approveMax ? uint(-1) : liquidity;
13        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
14        (amountA, amountB) = removeLiquidity(tokenA, tokenB, liquidity, amountAMin, amountBMin, to, deadline);
15    }
16
17
18    function removeLiquidityETHWithPermit(
19        address token,
20        uint liquidity,
21        uint amountTokenMin,
22        uint amountETHMin,
23        address to,
24        uint deadline,
25        bool approveMax, uint8 v, bytes32 r, bytes32 s
26    ) external virtual override returns (uint amountToken, uint amountETH) {
27        address pair = UniswapV2Library.pairFor(factory, token, WETH);
28        uint value = approveMax ? uint(-1) : liquidity;
29        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
30        (amountToken, amountETH) = removeLiquidityETH(token, liquidity, amountTokenMin, amountETHMin, to, deadline);
31    }
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1
2    // **** 移除流動性（支援轉帳收費代幣）****
3    function removeLiquidityETHSupportingFeeOnTransferTokens(
4        address token,
5        uint liquidity,
6        uint amountTokenMin,
7        uint amountETHMin,
8        address to,
9        uint deadline
10    ) public virtual override ensure(deadline) returns (uint amountETH) {
11        (, amountETH) = removeLiquidity(
12            token,
13            WETH,
14            liquidity,
15            amountTokenMin,
16            amountETHMin,
17            address(this),
18            deadline
19        );
20        TransferHelper.safeTransfer(token, to, IERC20(token).balanceOf(address(this)));
21        IWETH(WETH).withdraw(amountETH);
22        TransferHelper.safeTransferETH(to, amountETH);
23    }
24
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1
2
3    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
4        address token,
5        uint liquidity,
6        uint amountTokenMin,
7        uint amountETHMin,
8        address to,
9        uint deadline,
10        bool approveMax, uint8 v, bytes32 r, bytes32 s
11    ) external virtual override returns (uint amountETH) {
12        address pair = UniswapV2Library.pairFor(factory, token, WETH);
13        uint value = approveMax ? uint(-1) : liquidity;
14        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
15        amountETH = removeLiquidityETHSupportingFeeOnTransferTokens(
16            token, liquidity, amountTokenMin, amountETHMin, to, deadline
17        );
18    }
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