AlleyFactory

[
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "_feeToSetter",
        "type": "address"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "constructor"
  },
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "token0",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "token1",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "address",
        "name": "pair",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "name": "PairCreated",
    "type": "event"
  },
  {
    "inputs": [],
    "name": "INIT_CODE_PAIR_HASH",
    "outputs": [
      {
        "internalType": "bytes32",
        "name": "",
        "type": "bytes32"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "name": "allPairs",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "allPairsLength",
    "outputs": [
      {
        "internalType": "uint256",
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "tokenA",
        "type": "address"
      },
      {
        "internalType": "address",
        "name": "tokenB",
        "type": "address"
      }
    ],
    "name": "createPair",
    "outputs": [
      {
        "internalType": "address",
        "name": "pair",
        "type": "address"
      }
    ],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "feeTo",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "feeToSetter",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      },
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "name": "getPair",
    "outputs": [
      {
        "internalType": "address",
        "name": "",
        "type": "address"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  },
  {
    "inputs": [],
    "name": "pairCodeHash",
    "outputs": [
      {
        "internalType": "bytes32",
        "name": "",
        "type": "bytes32"
      }
    ],
    "stateMutability": "pure",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "_feeTo",
        "type": "address"
      }
    ],
    "name": "setFeeTo",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  },
  {
    "inputs": [
      {
        "internalType": "address",
        "name": "_feeToSetter",
        "type": "address"
      }
    ],
    "name": "setFeeToSetter",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
  }
]

// SPDX-License-Identifier: GPL-3.0

pragma solidity =0.6.12;

import './interfaces/IAlleyFactory.sol';
import './AlleyPair.sol';

contract AlleyFactory is IAlleyFactory {
    address public override feeTo;
    address public override feeToSetter;
    bytes32 public constant INIT_CODE_PAIR_HASH = keccak256(abi.encodePacked(type(AlleyPair).creationCode));

    mapping(address => mapping(address => address)) public override getPair;
    address[] public override allPairs;

    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    constructor(address _feeToSetter) public {
        feeToSetter = _feeToSetter;
    }

    function allPairsLength() external override view returns (uint) {
        return allPairs.length;
    }

    function pairCodeHash() external pure returns (bytes32) {
        return keccak256(type(AlleyPair).creationCode);
    }

    function createPair(address tokenA, address tokenB) external override returns (address pair) {
        require(tokenA != tokenB, 'Alley: IDENTICAL_ADDRESSES');
        (address token0, address token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
        require(token0 != address(0), 'Alley: ZERO_ADDRESS');
        require(getPair[token0][token1] == address(0), 'Alley: PAIR_EXISTS'); // single check is sufficient
        bytes memory bytecode = type(AlleyPair).creationCode;
        bytes32 salt = keccak256(abi.encodePacked(token0, token1));
        assembly {
            pair := create2(0, add(bytecode, 32), mload(bytecode), salt)
        }
        AlleyPair(pair).initialize(token0, token1);
        getPair[token0][token1] = pair;
        getPair[token1][token0] = pair; // populate mapping in the reverse direction
        allPairs.push(pair);
        emit PairCreated(token0, token1, pair, allPairs.length);
    }

    function setFeeTo(address _feeTo) external override {
        require(msg.sender == feeToSetter, 'Alley: FORBIDDEN');
        feeTo = _feeTo;
    }

    function setFeeToSetter(address _feeToSetter) external override {
        require(msg.sender == feeToSetter, 'Alley: FORBIDDEN');
        feeToSetter = _feeToSetter;
    }

}