Contract Name:
EtherVistaPair
Contract Source Code:
pragma solidity =0.5.16;
interface IEtherVistaPair {
event Approval(address indexed owner, address indexed spender, uint value);
event Transfer(address indexed from, address indexed to, uint value);
function setMetadata(string calldata website, string calldata image, string calldata description, string calldata chat, string calldata social) external;
function fetchMetadata() external view returns(string memory, string memory, string memory, string memory, string memory);
function name() external pure returns (string memory);
function symbol() external pure returns (string memory);
function decimals() external pure returns (uint8);
function totalSupply() external view returns (uint);
function balanceOf(address owner) external view returns (uint);
function allowance(address owner, address spender) external view returns (uint);
function updateProvider(address user) external;
function euler(uint) external view returns (uint256);
function viewShare() external view returns (uint256 share);
function claimShare() external;
function poolBalance() external view returns (uint);
function totalCollected() external view returns (uint);
function updateProtocol(address) external;
function setProtocol() external;
function protocol() external view returns (address);
function payableProtocol() external view returns (address payable origin);
function creator() external view returns (address);
function renounce() external;
function setFees() external;
function updateFees(uint8, uint8, uint8, uint8) external;
function buyLpFee() external view returns (uint8);
function sellLpFee() external view returns (uint8);
function buyProtocolFee() external view returns (uint8);
function sellProtocolFee() external view returns (uint8);
function buyTotalFee() external view returns (uint8);
function sellTotalFee() external view returns (uint8);
function approve(address spender, uint value) external returns (bool);
function transfer(address to, uint value) external returns (bool);
function transferFrom(address from, address to, uint value) external returns (bool);
function DOMAIN_SEPARATOR() external view returns (bytes32);
function PERMIT_TYPEHASH() external pure returns (bytes32);
function nonces(address owner) external view returns (uint);
function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
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);
function MINIMUM_LIQUIDITY() external pure returns (uint);
function factory() external view returns (address);
function token0() external view returns (address);
function token1() external view returns (address);
function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
function price0CumulativeLast() external view returns (uint);
function price1CumulativeLast() external view returns (uint);
function kLast() external view returns (uint);
function first_mint(address to, uint8 buyLp, uint8 sellLp, uint8 buyProtocol, uint8 sellProtocol, address protocolAddress) external returns (uint liquidity);
function mint(address to) external returns (uint liquidity);
function burn(address to) external returns (uint amount0, uint amount1);
function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
function skim(address to) external;
function sync() external;
function initialize(address _token0, address _token1) external;
}
interface IEtherVistaERC20 {
event Approval(address indexed owner, address indexed spender, uint value);
event Transfer(address indexed from, address indexed to, uint value);
function name() external pure returns (string memory);
function symbol() external pure returns (string memory);
function decimals() external pure returns (uint8);
function totalSupply() external view returns (uint);
function balanceOf(address owner) external view returns (uint);
function allowance(address owner, address spender) external view returns (uint);
function approve(address spender, uint value) external returns (bool);
function transfer(address to, uint value) external returns (bool);
function transferFrom(address from, address to, uint value) external returns (bool);
function DOMAIN_SEPARATOR() external view returns (bytes32);
function PERMIT_TYPEHASH() external pure returns (bytes32);
function nonces(address owner) external view returns (uint);
function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
}
interface IERC20 {
event Approval(address indexed owner, address indexed spender, uint value);
event Transfer(address indexed from, address indexed to, uint value);
function name() external view returns (string memory);
function symbol() external view returns (string memory);
function decimals() external view returns (uint8);
function totalSupply() external view returns (uint);
function balanceOf(address owner) external view returns (uint);
function allowance(address owner, address spender) external view returns (uint);
function approve(address spender, uint value) external returns (bool);
function transfer(address to, uint value) external returns (bool);
function transferFrom(address from, address to, uint value) external returns (bool);
}
interface IEtherVistaFactory {
event PairCreated(address indexed token0, address indexed token1, address pair, uint);
function feeTo() external view returns (address);
function feeToSetter() external view returns (address);
function routerSetter() external view returns (address);
function router() external view returns (address);
function getPair(address tokenA, address tokenB) external view returns (address pair);
function allPairs(uint) external view returns (address pair);
function allPairsLength() external view returns (uint);
function createPair(address tokenA, address tokenB) external returns (address pair);
function setFeeTo(address) external;
function setFeeToSetter(address) external;
function setRouterSetter(address) external;
function setRouter(address) external;
}
interface IUniswapV2Callee {
function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external;
}
library SafeMath {
function add(uint x, uint y) internal pure returns (uint z) {
require((z = x + y) >= x, 'ds-math-add-overflow');
}
function sub(uint x, uint y) internal pure returns (uint z) {
require((z = x - y) <= x, 'ds-math-sub-underflow');
}
function mul(uint x, uint y) internal pure returns (uint z) {
require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
}
}
library Math {
function min(uint x, uint y) internal pure returns (uint z) {
z = x < y ? x : y;
}
// babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)
function sqrt(uint y) internal pure returns (uint z) {
if (y > 3) {
z = y;
uint x = y / 2 + 1;
while (x < z) {
z = x;
x = (y / x + x) / 2;
}
} else if (y != 0) {
z = 1;
}
}
}
library UQ112x112 {
uint224 constant Q112 = 2**112;
// encode a uint112 as a UQ112x112
function encode(uint112 y) internal pure returns (uint224 z) {
z = uint224(y) * Q112; // never overflows
}
// divide a UQ112x112 by a uint112, returning a UQ112x112
function uqdiv(uint224 x, uint112 y) internal pure returns (uint224 z) {
z = x / uint224(y);
}
}
contract EtherVistaERC20 is IEtherVistaERC20 {
using SafeMath for uint;
string public constant name = 'VISTA';
string public constant symbol = 'VISTA-LP';
uint8 public constant decimals = 18;
uint public totalSupply;
address public factory;
mapping(address => uint) public balanceOf;
mapping(address => mapping(address => uint)) public allowance;
bytes32 public DOMAIN_SEPARATOR;
// keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
mapping(address => uint) public nonces;
event Approval(address indexed owner, address indexed spender, uint value);
event Transfer(address indexed from, address indexed to, uint value);
constructor() public {
uint chainId;
assembly {
chainId := chainid
}
factory = msg.sender;
DOMAIN_SEPARATOR = keccak256(
abi.encode(
keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
keccak256(bytes(name)),
keccak256(bytes('1')),
chainId,
address(this)
)
);
}
function _mint(address to, uint value) internal {
totalSupply = totalSupply.add(value);
balanceOf[to] = balanceOf[to].add(value);
emit Transfer(address(0), to, value);
}
function _burn(address from, uint value) internal {
balanceOf[from] = balanceOf[from].sub(value);
totalSupply = totalSupply.sub(value);
emit Transfer(from, address(0), value);
}
function _approve(address owner, address spender, uint value) private {
allowance[owner][spender] = value;
emit Approval(owner, spender, value);
}
function _transfer(address from, address to, uint value) private {
balanceOf[from] = balanceOf[from].sub(value);
balanceOf[to] = balanceOf[to].add(value);
emit Transfer(from, to, value);
}
function transfer(address to, uint value) external returns (bool) {
if (to != 0x000000000000000000000000000000000000dEaD) {
require(msg.sender == IEtherVistaFactory(factory).router(), 'EtherVistaPair: FORBIDDEN');
}
_transfer(msg.sender, to, value);
return true;
}
function approve(address spender, uint value) external returns (bool) {
require(spender == IEtherVistaFactory(factory).router(), 'EtherVistaPair: FORBIDDEN');
_approve(msg.sender, spender, value);
return true;
}
function transferFrom(address from, address to, uint value) external returns (bool) {
require(msg.sender == IEtherVistaFactory(factory).router(), 'EtherVistaPair: FORBIDDEN');
if (allowance[from][msg.sender] != uint(-1)) {
allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
}
_transfer(from, to, value);
return true;
}
function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
require(deadline >= block.timestamp, 'EtherVista: EXPIRED');
require(spender == IEtherVistaFactory(factory).router(), 'EtherVistaPair: FORBIDDEN');
bytes32 digest = keccak256(
abi.encodePacked(
'\x19\x01',
DOMAIN_SEPARATOR,
keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
)
);
address recoveredAddress = ecrecover(digest, v, r, s);
require(recoveredAddress != address(0) && recoveredAddress == owner, 'EtherVista: INVALID_SIGNATURE');
_approve(owner, spender, value);
}
}
contract EtherVistaPair is IEtherVistaPair, EtherVistaERC20 {
using SafeMath for uint;
using UQ112x112 for uint224;
uint public constant MINIMUM_LIQUIDITY = 10**3;
uint256 private bigNumber = 10**20; //prevents liqFee/totalSupply from rounding to 0.
bytes4 private constant SELECTOR = bytes4(keccak256(bytes('transfer(address,uint256)')));
address public factory;
address public token0;
address public token1;
uint8 public buyLpFee;
uint8 public sellLpFee;
uint8 public buyProtocolFee;
uint8 public sellProtocolFee;
uint8 public buyTotalFee;
uint8 public sellTotalFee;
uint256 public startTime_fees = 0;
uint8 public future_buyLpFee;
uint8 public future_sellLpFee;
uint8 public future_buyProtocolFee;
uint8 public future_sellProtocolFee ;
uint256 public totalCollected;
uint public poolBalance;
uint256 public startTime_protocol = 0;
address public protocol;
address public future_protocol;
address public creator;
uint256 public creation_time;
string public websiteUrl = "Null";
string public imageUrl = "Null"; //IPFS link
string public tokenDescription = "Null";
string public chatUrl = "Null";
string public socialUrl = "Null";
struct Provider {
uint256 lp;
uint256 euler0;
}
uint256[] public euler;
mapping(address => Provider) public Providers;
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, 'EtherVista: LOCKED');
unlocked = 0;
_;
unlocked = 1;
}
//called everytime a swap is performed
function() external payable {
require(msg.sender == IEtherVistaFactory(factory).router(), 'EtherVistaPair: FORBIDDEN');
poolBalance += msg.value;
totalCollected += msg.value;
updateEuler(msg.value);
}
//updates the euler constant - occurs everytime a swap is performed
function updateEuler(uint256 liqFee) internal {
if (euler.length == 0){
euler.push((liqFee*bigNumber)/totalSupply);
}else{
euler.push(euler[euler.length - 1] + (liqFee*bigNumber)/totalSupply);
}
}
//called everytime liquidity is added/removed by the user
function updateProvider(address user) external {
require(msg.sender == IEtherVistaFactory(factory).router(), 'EtherVistaPair: FORBIDDEN');
if (euler.length == 0){
Providers[user] = Provider(balanceOf[user], 0);
}else{
Providers[user] = Provider(balanceOf[user], euler[euler.length - 1]);
}
}
function claimShare() public lock {
require(euler.length > 0, 'EtherVistaPair: Nothing to Claim');
uint256 share = (Providers[msg.sender].lp * (euler[euler.length - 1] - Providers[msg.sender].euler0))/bigNumber;
Providers[msg.sender] = Provider(balanceOf[msg.sender], euler[euler.length - 1]);
poolBalance -= share;
(bool sent,) = msg.sender.call.value(share)("");
require(sent, "Failed to send Ether");
}
function viewShare() public view returns (uint256 share) {
if (euler.length == 0){
return 0;
}else{
return Providers[msg.sender].lp * (euler[euler.length - 1] - Providers[msg.sender].euler0)/bigNumber;
}
}
function updateFees(uint8 buyLpFuture, uint8 sellLpFuture, uint8 buyProtocolFuture, uint8 sellProtocolFuture) external {
require(msg.sender == creator);
startTime_fees = block.timestamp;
future_buyLpFee = buyLpFuture;
future_sellLpFee = sellLpFuture;
future_buyProtocolFee = buyProtocolFuture;
future_sellProtocolFee = sellProtocolFuture;
}
function setFees() external {
require(startTime_fees != 0);
require(msg.sender == creator && block.timestamp - startTime_fees >= 3 days);
buyLpFee = future_buyLpFee;
sellLpFee = future_sellLpFee;
buyProtocolFee = future_buyProtocolFee;
sellProtocolFee = future_sellProtocolFee;
buyTotalFee = future_buyLpFee + future_buyProtocolFee + 1;
sellTotalFee = future_sellLpFee + future_sellProtocolFee + 1;
}
function updateProtocol(address protocolFuture) external {
require(msg.sender == creator);
startTime_protocol = block.timestamp;
future_protocol = protocolFuture;
}
function setProtocol() external {
require(startTime_protocol != 0);
require(msg.sender == creator && block.timestamp - startTime_protocol >= 3 days);
protocol = future_protocol;
}
function payableProtocol() external view returns (address payable) {
return address(uint160(protocol));
}
function setMetadata(string calldata website, string calldata image, string calldata description, string calldata chat, string calldata social) external {
require(msg.sender == creator);
websiteUrl = website;
imageUrl = image;
tokenDescription = description;
chatUrl = chat;
socialUrl = social;
}
function fetchMetadata() public view returns(string memory, string memory, string memory, string memory, string memory) {
return (websiteUrl, imageUrl, tokenDescription, chatUrl, socialUrl);
}
function renounce() external {
require(msg.sender == creator);
creator = 0x000000000000000000000000000000000000dEaD;
}
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))), 'EtherVista: 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, 'EtherVistaPair: 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), 'EtherVistaPair: 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);
}
// if fee is on, mint liquidity equivalent to 1/6th of the growth in sqrt(k). This will never be on.
function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
address feeTo = IEtherVistaFactory(factory).feeTo();
feeOn = feeTo != address(0);
uint _kLast = kLast; // gas savings
if (feeOn) {
if (_kLast != 0) {
uint rootK = Math.sqrt(uint(_reserve0).mul(_reserve1));
uint rootKLast = Math.sqrt(_kLast);
if (rootK > rootKLast) {
uint numerator = totalSupply.mul(rootK.sub(rootKLast));
uint denominator = rootK.mul(5).add(rootKLast);
uint liquidity = numerator / denominator;
if (liquidity > 0) _mint(feeTo, liquidity);
}
}
} else if (_kLast != 0) {
kLast = 0;
}
}
// this low-level function should be called from a contract which performs important safety checks
function first_mint(address to, uint8 buyLp, uint8 sellLp, uint8 buyProtocol, uint8 sellProtocol, address protocolAddress) external lock returns (uint liquidity) {
require(msg.sender == IEtherVistaFactory(factory).router(), 'EtherVistaPair: FORBIDDEN');
(uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
uint balance0 = IERC20(token0).balanceOf(address(this));
uint balance1 = IERC20(token1).balanceOf(address(this));
uint amount0 = balance0.sub(_reserve0);
uint amount1 = balance1.sub(_reserve1);
bool feeOn = _mintFee(_reserve0, _reserve1);
uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
require(_totalSupply == 0);
liquidity = Math.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
_mint(address(0), MINIMUM_LIQUIDITY); // permanently lock the first MINIMUM_LIQUIDITY tokens
creator = to;
creation_time = block.timestamp;
protocol = protocolAddress;
buyLpFee = buyLp;
sellLpFee = sellLp;
buyProtocolFee = buyProtocol;
sellProtocolFee = sellProtocol;
buyTotalFee = buyLp + buyProtocol + 1;
sellTotalFee = sellLp + sellProtocol + 1;
require(liquidity > 0, 'EtherVistaPair: INSUFFICIENT_LIQUIDITY_MINTED');
_mint(to, liquidity);
_update(balance0, balance1, _reserve0, _reserve1);
if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
emit Mint(msg.sender, amount0, amount1);
}
// this low-level function should be called from a contract which performs important safety checks
function mint(address to) external lock returns (uint liquidity) {
require(msg.sender == IEtherVistaFactory(factory).router(), 'EtherVistaPair: FORBIDDEN');
(uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
uint balance0 = IERC20(token0).balanceOf(address(this));
uint balance1 = IERC20(token1).balanceOf(address(this));
uint amount0 = balance0.sub(_reserve0);
uint amount1 = balance1.sub(_reserve1);
bool feeOn = _mintFee(_reserve0, _reserve1);
uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
if (_totalSupply == 0) {
revert('Use first_mint instead');
} else {
liquidity = Math.min(amount0.mul(_totalSupply) / _reserve0, amount1.mul(_totalSupply) / _reserve1);
}
require(liquidity > 0, 'EtherVistaPair: INSUFFICIENT_LIQUIDITY_MINTED');
_mint(to, liquidity);
_update(balance0, balance1, _reserve0, _reserve1);
if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
emit Mint(msg.sender, amount0, amount1);
}
// 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) {
require(msg.sender == IEtherVistaFactory(factory).router(), 'EtherVistaPair: FORBIDDEN');
require(block.timestamp - creation_time >= 5 days, 'EtherVistaPair: FORBIDDEN RUGPULL');
(uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
address _token0 = token0; // gas savings
address _token1 = token1; // gas savings
uint balance0 = IERC20(_token0).balanceOf(address(this));
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, 'EtherVistaPair: 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(msg.sender == IEtherVistaFactory(factory).router(), 'EtherVistaPair: FORBIDDEN');
require(amount0Out > 0 || amount1Out > 0, 'EtherVistaPair: INSUFFICIENT_OUTPUT_AMOUNT');
(uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
require(amount0Out < _reserve0 && amount1Out < _reserve1, 'EtherVista: 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, 'EtherVistaPair: 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, 'EtherVista: INSUFFICIENT_INPUT_AMOUNT');
{
require(balance0 * balance1 >= reserve0 * reserve1, "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);
}
}