Contract Source Code:
File 1 of 1 : MdexPair
pragma solidity =0.5.16;
interface IMdexFactory {
event PairCreated(address indexed token0, address indexed token1, address pair, uint256);
function FEE_RATE_DENOMINATOR() external view returns (uint256);
function feeRateNumerator() external view returns (uint256);
function feeTo() external view returns (address);
function feeToSetter() external view returns (address);
function feeToRate() external view returns (uint256);
function initCodeHash() external view returns (bytes32);
function pairFeeToRate(address) external view returns (uint256);
function pairFees(address) external view returns (uint256);
function getPair(address tokenA, address tokenB) external view returns (address pair);
function allPairs(uint256) external view returns (address pair);
function allPairsLength() external view returns (uint256);
function createPair(address tokenA, address tokenB) external returns (address pair);
function setFeeTo(address) external;
function setFeeToSetter(address) external;
function addPair(address) external returns (bool);
function delPair(address) external returns (bool);
function getSupportListLength() external view returns (uint256);
function isSupportPair(address pair) external view returns (bool);
function getSupportPair(uint256 index) external view returns (address);
function setFeeRateNumerator(uint256) external;
function setPairFees(address pair, uint256 fee) external;
function setDefaultFeeToRate(uint256) external;
function setPairFeeToRate(address pair, uint256 rate) external;
function getPairFees(address) external view returns (uint256);
function getPairRate(address) external view returns (uint256);
function sortTokens(address tokenA, address tokenB) external pure returns (address token0, address token1);
function pairFor(address tokenA, address tokenB) external view returns (address pair);
function getReserves(address tokenA, address tokenB) external view returns (uint256 reserveA, uint256 reserveB);
function quote(
uint256 amountA,
uint256 reserveA,
uint256 reserveB
) external pure returns (uint256 amountB);
function getAmountOut(
uint256 amountIn,
uint256 reserveIn,
uint256 reserveOut,
address token0,
address token1
) external view returns (uint256 amountOut);
function getAmountIn(
uint256 amountOut,
uint256 reserveIn,
uint256 reserveOut,
address token0,
address token1
) external view returns (uint256 amountIn);
function getAmountsOut(uint256 amountIn, address[] calldata path) external view returns (uint256[] memory amounts);
function getAmountsIn(uint256 amountOut, address[] calldata path) external view returns (uint256[] memory amounts);
}
interface IMdexPair {
event Approval(address indexed owner, address indexed spender, uint256 value);
event Transfer(address indexed from, address indexed to, uint256 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 (uint256);
function balanceOf(address owner) external view returns (uint256);
function allowance(address owner, address spender) external view returns (uint256);
function approve(address spender, uint256 value) external returns (bool);
function transfer(address to, uint256 value) external returns (bool);
function transferFrom(
address from,
address to,
uint256 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 (uint256);
function permit(
address owner,
address spender,
uint256 value,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) external;
event Mint(address indexed sender, uint256 amount0, uint256 amount1);
event Burn(address indexed sender, uint256 amount0, uint256 amount1, address indexed to);
event Swap(address indexed sender, uint256 amount0In, uint256 amount1In, uint256 amount0Out, uint256 amount1Out, address indexed to);
event Sync(uint112 reserve0, uint112 reserve1);
function MINIMUM_LIQUIDITY() external pure returns (uint256);
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 (uint256);
function price1CumulativeLast() external view returns (uint256);
function kLast() external view returns (uint256);
function mint(address to) external returns (uint256 liquidity);
function burn(address to) external returns (uint256 amount0, uint256 amount1);
function swap(
uint256 amount0Out,
uint256 amount1Out,
address to,
bytes calldata data
) external;
function skim(address to) external;
function sync() external;
function initialize(address, address) external;
}
interface IMdexERC20 {
event Approval(address indexed owner, address indexed spender, uint256 value);
event Transfer(address indexed from, address indexed to, uint256 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 (uint256);
function balanceOf(address owner) external view returns (uint256);
function allowance(address owner, address spender) external view returns (uint256);
function approve(address spender, uint256 value) external returns (bool);
function transfer(address to, uint256 value) external returns (bool);
function transferFrom(
address from,
address to,
uint256 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 (uint256);
function permit(
address owner,
address spender,
uint256 value,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) external;
}
interface IERC20 {
event Approval(address indexed owner, address indexed spender, uint256 value);
event Transfer(address indexed from, address indexed to, uint256 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 (uint256);
function balanceOf(address owner) external view returns (uint256);
function allowance(address owner, address spender) external view returns (uint256);
function approve(address spender, uint256 value) external returns (bool);
function transfer(address to, uint256 value) external returns (bool);
function transferFrom(
address from,
address to,
uint256 value
) external returns (bool);
}
interface IswapV2Callee {
function swapV2Call(
address sender,
uint256 amount0,
uint256 amount1,
bytes calldata data
) external;
}
library SafeMath {
uint256 constant WAD = 10**18;
uint256 constant RAY = 10**27;
function wad() public pure returns (uint256) {
return WAD;
}
function ray() public pure returns (uint256) {
return RAY;
}
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a, "SafeMath: addition overflow");
return c;
}
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
return sub(a, b, "SafeMath: subtraction overflow");
}
function sub(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
require(b <= a, errorMessage);
uint256 c = a - b;
return c;
}
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
if (a == 0) {
return 0;
}
uint256 c = a * b;
require(c / a == b, "SafeMath: multiplication overflow");
return c;
}
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return div(a, b, "SafeMath: division by zero");
}
function div(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
// Solidity only automatically asserts when dividing by 0
require(b > 0, errorMessage);
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return mod(a, b, "SafeMath: modulo by zero");
}
function mod(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
require(b != 0, errorMessage);
return a % b;
}
function min(uint256 a, uint256 b) internal pure returns (uint256) {
return a <= b ? a : b;
}
function max(uint256 a, uint256 b) internal pure returns (uint256) {
return a >= b ? a : b;
}
function sqrt(uint256 a) internal pure returns (uint256 b) {
if (a > 3) {
b = a;
uint256 x = a / 2 + 1;
while (x < b) {
b = x;
x = (a / x + x) / 2;
}
} else if (a != 0) {
b = 1;
}
}
function wmul(uint256 a, uint256 b) internal pure returns (uint256) {
return mul(a, b) / WAD;
}
function wmulRound(uint256 a, uint256 b) internal pure returns (uint256) {
return add(mul(a, b), WAD / 2) / WAD;
}
function rmul(uint256 a, uint256 b) internal pure returns (uint256) {
return mul(a, b) / RAY;
}
function rmulRound(uint256 a, uint256 b) internal pure returns (uint256) {
return add(mul(a, b), RAY / 2) / RAY;
}
function wdiv(uint256 a, uint256 b) internal pure returns (uint256) {
return div(mul(a, WAD), b);
}
function wdivRound(uint256 a, uint256 b) internal pure returns (uint256) {
return add(mul(a, WAD), b / 2) / b;
}
function rdiv(uint256 a, uint256 b) internal pure returns (uint256) {
return div(mul(a, RAY), b);
}
function rdivRound(uint256 a, uint256 b) internal pure returns (uint256) {
return add(mul(a, RAY), b / 2) / b;
}
function wpow(uint256 x, uint256 n) internal pure returns (uint256) {
uint256 result = WAD;
while (n > 0) {
if (n % 2 != 0) {
result = wmul(result, x);
}
x = wmul(x, x);
n /= 2;
}
return result;
}
function rpow(uint256 x, uint256 n) internal pure returns (uint256) {
uint256 result = RAY;
while (n > 0) {
if (n % 2 != 0) {
result = rmul(result, x);
}
x = rmul(x, x);
n /= 2;
}
return result;
}
}
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);
}
}
library EnumerableSet {
// To implement this library for multiple types with as little code
// repetition as possible, we write it in terms of a generic Set type with
// bytes32 values.
// The Set implementation uses private functions, and user-facing
// implementations (such as AddressSet) are just wrappers around the
// underlying Set.
// This means that we can only create new EnumerableSets for types that fit
// in bytes32.
struct Set {
// Storage of set values
bytes32[] _values;
// Position of the value in the `values` array, plus 1 because index 0
// means a value is not in the set.
mapping(bytes32 => uint256) _indexes;
}
/**
* @dev Add a value to a set. O(1).
*
* Returns true if the value was added to the set, that is if it was not
* already present.
*/
function _add(Set storage set, bytes32 value) private returns (bool) {
if (!_contains(set, value)) {
set._values.push(value);
// The value is stored at length-1, but we add 1 to all indexes
// and use 0 as a sentinel value
set._indexes[value] = set._values.length;
return true;
} else {
return false;
}
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the value was removed from the set, that is if it was
* present.
*/
function _remove(Set storage set, bytes32 value) private returns (bool) {
// We read and store the value's index to prevent multiple reads from the same storage slot
uint256 valueIndex = set._indexes[value];
if (valueIndex != 0) {
// Equivalent to contains(set, value)
// To delete an element from the _values array in O(1), we swap the element to delete with the last one in
// the array, and then remove the last element (sometimes called as 'swap and pop').
// This modifies the order of the array, as noted in {at}.
uint256 toDeleteIndex = valueIndex - 1;
uint256 lastIndex = set._values.length - 1;
// When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
// so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.
bytes32 lastvalue = set._values[lastIndex];
// Move the last value to the index where the value to delete is
set._values[toDeleteIndex] = lastvalue;
// Update the index for the moved value
set._indexes[lastvalue] = toDeleteIndex + 1;
// All indexes are 1-based
// Delete the slot where the moved value was stored
set._values.pop();
// Delete the index for the deleted slot
delete set._indexes[value];
return true;
} else {
return false;
}
}
/**
* @dev Returns true if the value is in the set. O(1).
*/
function _contains(Set storage set, bytes32 value) private view returns (bool) {
return set._indexes[value] != 0;
}
/**
* @dev Returns the number of values on the set. O(1).
*/
function _length(Set storage set) private view returns (uint256) {
return set._values.length;
}
/**
* @dev Returns the value stored at position `index` in the set. O(1).
*
* Note that there are no guarantees on the ordering of values inside the
* array, and it may change when more values are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function _at(Set storage set, uint256 index) private view returns (bytes32) {
require(set._values.length > index, "EnumerableSet: index out of bounds");
return set._values[index];
}
// Bytes32Set
struct Bytes32Set {
Set _inner;
}
/**
* @dev Add a value to a set. O(1).
*
* Returns true if the value was added to the set, that is if it was not
* already present.
*/
function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
return _add(set._inner, value);
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the value was removed from the set, that is if it was
* present.
*/
function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
return _remove(set._inner, value);
}
/**
* @dev Returns true if the value is in the set. O(1).
*/
function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
return _contains(set._inner, value);
}
/**
* @dev Returns the number of values in the set. O(1).
*/
function length(Bytes32Set storage set) internal view returns (uint256) {
return _length(set._inner);
}
/**
* @dev Returns the value stored at position `index` in the set. O(1).
*
* Note that there are no guarantees on the ordering of values inside the
* array, and it may change when more values are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
return _at(set._inner, index);
}
// AddressSet
struct AddressSet {
Set _inner;
}
/**
* @dev Add a value to a set. O(1).
*
* Returns true if the value was added to the set, that is if it was not
* already present.
*/
function add(AddressSet storage set, address value) internal returns (bool) {
return _add(set._inner, bytes32(uint256(value)));
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the value was removed from the set, that is if it was
* present.
*/
function remove(AddressSet storage set, address value) internal returns (bool) {
return _remove(set._inner, bytes32(uint256(value)));
}
/**
* @dev Returns true if the value is in the set. O(1).
*/
function contains(AddressSet storage set, address value) internal view returns (bool) {
return _contains(set._inner, bytes32(uint256(value)));
}
/**
* @dev Returns the number of values in the set. O(1).
*/
function length(AddressSet storage set) internal view returns (uint256) {
return _length(set._inner);
}
/**
* @dev Returns the value stored at position `index` in the set. O(1).
*
* Note that there are no guarantees on the ordering of values inside the
* array, and it may change when more values are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function at(AddressSet storage set, uint256 index) internal view returns (address) {
return address(uint256(_at(set._inner, index)));
}
// UintSet
struct UintSet {
Set _inner;
}
/**
* @dev Add a value to a set. O(1).
*
* Returns true if the value was added to the set, that is if it was not
* already present.
*/
function add(UintSet storage set, uint256 value) internal returns (bool) {
return _add(set._inner, bytes32(value));
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the value was removed from the set, that is if it was
* present.
*/
function remove(UintSet storage set, uint256 value) internal returns (bool) {
return _remove(set._inner, bytes32(value));
}
/**
* @dev Returns true if the value is in the set. O(1).
*/
function contains(UintSet storage set, uint256 value) internal view returns (bool) {
return _contains(set._inner, bytes32(value));
}
/**
* @dev Returns the number of values on the set. O(1).
*/
function length(UintSet storage set) internal view returns (uint256) {
return _length(set._inner);
}
/**
* @dev Returns the value stored at position `index` in the set. O(1).
*
* Note that there are no guarantees on the ordering of values inside the
* array, and it may change when more values are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function at(UintSet storage set, uint256 index) internal view returns (uint256) {
return uint256(_at(set._inner, index));
}
}
contract MdexERC20 is IMdexERC20 {
using SafeMath for uint256;
string public constant name = "MDEX LP Token";
string public constant symbol = "ETH_MDEX_LP";
uint8 public constant decimals = 18;
uint256 public totalSupply;
mapping(address => uint256) public balanceOf;
mapping(address => mapping(address => uint256)) 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 => uint256) public nonces;
event Approval(address indexed owner, address indexed spender, uint256 value);
event Transfer(address indexed from, address indexed to, uint256 value);
constructor() public {
uint256 chainId;
assembly {
chainId := chainid
}
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, uint256 value) internal {
totalSupply = totalSupply.add(value);
balanceOf[to] = balanceOf[to].add(value);
emit Transfer(address(0), to, value);
}
function _burn(address from, uint256 value) internal {
balanceOf[from] = balanceOf[from].sub(value);
totalSupply = totalSupply.sub(value);
emit Transfer(from, address(0), value);
}
function _approve(
address owner,
address spender,
uint256 value
) private {
allowance[owner][spender] = value;
emit Approval(owner, spender, value);
}
function _transfer(
address from,
address to,
uint256 value
) private {
balanceOf[from] = balanceOf[from].sub(value);
balanceOf[to] = balanceOf[to].add(value);
emit Transfer(from, to, value);
}
function approve(address spender, uint256 value) external returns (bool) {
_approve(msg.sender, spender, value);
return true;
}
function transfer(address to, uint256 value) external returns (bool) {
_transfer(msg.sender, to, value);
return true;
}
function transferFrom(
address from,
address to,
uint256 value
) external returns (bool) {
if (allowance[from][msg.sender] != uint256(-1)) {
allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
}
_transfer(from, to, value);
return true;
}
function permit(
address owner,
address spender,
uint256 value,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) external {
require(deadline >= block.timestamp, "MdexSwap: EXPIRED");
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, "MdexSwap: INVALID_SIGNATURE");
_approve(owner, spender, value);
}
}
contract MdexPair is IMdexPair, MdexERC20 {
using SafeMath for uint256;
using UQ112x112 for uint224;
uint256 public constant MINIMUM_LIQUIDITY = 10**3;
bytes4 private constant SELECTOR = bytes4(keccak256(bytes("transfer(address,uint256)")));
address public factory;
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
uint256 public price0CumulativeLast;
uint256 public price1CumulativeLast;
uint256 public kLast; // reserve0 * reserve1, as of immediately after the most recent liquidity event
uint256 private unlocked = 1;
modifier lock() {
require(unlocked == 1, "MdexSwap: 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,
uint256 value
) private {
(bool success, bytes memory data) = token.call(abi.encodeWithSelector(SELECTOR, to, value));
require(success && (data.length == 0 || abi.decode(data, (bool))), "MdexSwap: TRANSFER_FAILED");
}
event Mint(address indexed sender, uint256 amount0, uint256 amount1);
event Burn(address indexed sender, uint256 amount0, uint256 amount1, address indexed to);
event Swap(address indexed sender, uint256 amount0In, uint256 amount1In, uint256 amount0Out, uint256 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, "MdexSwap: FORBIDDEN");
// sufficient check
token0 = _token0;
token1 = _token1;
}
// update reserves and, on the first call per block, price accumulators
function _update(
uint256 balance0,
uint256 balance1,
uint112 _reserve0,
uint112 _reserve1
) private {
require(balance0 <= uint112(-1) && balance1 <= uint112(-1), "MdexSwap: 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 += uint256(UQ112x112.encode(_reserve1).uqdiv(_reserve0)) * timeElapsed;
price1CumulativeLast += uint256(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)
function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
address feeTo = IMdexFactory(factory).feeTo();
feeOn = feeTo != address(0) && IMdexFactory(factory).getPairRate(address(this)) != 9;
uint256 _kLast = kLast;
// gas savings
if (feeOn) {
if (_kLast != 0) {
uint256 rootK = SafeMath.sqrt(uint256(_reserve0).mul(_reserve1));
uint256 rootKLast = SafeMath.sqrt(_kLast);
if (rootK > rootKLast) {
uint256 numerator = totalSupply.mul(rootK.sub(rootKLast));
uint256 denominator = rootK.mul(IMdexFactory(factory).getPairRate(address(this))).add(rootKLast);
uint256 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 mint(address to) external lock returns (uint256 liquidity) {
(uint112 _reserve0, uint112 _reserve1, ) = getReserves();
// gas savings
uint256 balance0 = IERC20(token0).balanceOf(address(this));
uint256 balance1 = IERC20(token1).balanceOf(address(this));
uint256 amount0 = balance0.sub(_reserve0);
uint256 amount1 = balance1.sub(_reserve1);
bool feeOn = _mintFee(_reserve0, _reserve1);
uint256 _totalSupply = totalSupply;
// gas savings, must be defined here since totalSupply can update in _mintFee
if (_totalSupply == 0) {
liquidity = SafeMath.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
_mint(address(0), MINIMUM_LIQUIDITY);
// permanently lock the first MINIMUM_LIQUIDITY tokens
} else {
liquidity = SafeMath.min(amount0.mul(_totalSupply) / _reserve0, amount1.mul(_totalSupply) / _reserve1);
}
require(liquidity > 0, "MdexSwap: INSUFFICIENT_LIQUIDITY_MINTED");
_mint(to, liquidity);
_update(balance0, balance1, _reserve0, _reserve1);
if (feeOn) kLast = uint256(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 (uint256 amount0, uint256 amount1) {
(uint112 _reserve0, uint112 _reserve1, ) = getReserves();
// gas savings
address _token0 = token0;
// gas savings
address _token1 = token1;
// gas savings
uint256 balance0 = IERC20(_token0).balanceOf(address(this));
uint256 balance1 = IERC20(_token1).balanceOf(address(this));
uint256 liquidity = balanceOf[address(this)];
bool feeOn = _mintFee(_reserve0, _reserve1);
uint256 _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, "MdexSwap: 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 = uint256(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(
uint256 amount0Out,
uint256 amount1Out,
address to,
bytes calldata data
) external lock {
require(amount0Out > 0 || amount1Out > 0, "MdexSwap: INSUFFICIENT_OUTPUT_AMOUNT");
(uint112 _reserve0, uint112 _reserve1, ) = getReserves();
// gas savings
require(amount0Out < _reserve0 && amount1Out < _reserve1, "MdexSwap: INSUFFICIENT_LIQUIDITY");
uint256 balance0;
uint256 balance1;
{
// scope for _token{0,1}, avoids stack too deep errors
address _token0 = token0;
address _token1 = token1;
require(to != _token0 && to != _token1, "MdexSwap: 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) IswapV2Callee(to).swapV2Call(msg.sender, amount0Out, amount1Out, data);
balance0 = IERC20(_token0).balanceOf(address(this));
balance1 = IERC20(_token1).balanceOf(address(this));
}
uint256 amount0In = balance0 > _reserve0 - amount0Out ? balance0 - (_reserve0 - amount0Out) : 0;
uint256 amount1In = balance1 > _reserve1 - amount1Out ? balance1 - (_reserve1 - amount1Out) : 0;
require(amount0In > 0 || amount1In > 0, "MdexSwap: INSUFFICIENT_INPUT_AMOUNT");
{
// scope for reserve{0,1}Adjusted, avoids stack too deep errors
uint256 balance0Adjusted = balance0.mul(1e4).sub(amount0In.mul(IMdexFactory(factory).getPairFees(address(this))));
uint256 balance1Adjusted = balance1.mul(1e4).sub(amount1In.mul(IMdexFactory(factory).getPairFees(address(this))));
require(balance0Adjusted.mul(balance1Adjusted) >= uint256(_reserve0).mul(_reserve1).mul(1e8), "MdexSwap: 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);
}
}