Address Details

contract

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.5.13;

import "openzeppelin-solidity/contracts/math/SafeMath.sol";

import "./LinkedList.sol";

/**
 * @title Maintains a doubly linked list keyed by address.
 * @dev Following the `next` pointers will lead you to the head, rather than the tail.
 */
library AddressLinkedList {
  using LinkedList for LinkedList.List;
  using SafeMath for uint256;

  function toBytes(address a) public pure returns (bytes32) {
    return bytes32(uint256(a) << 96);
  }

  function toAddress(bytes32 b) public pure returns (address) {
    return address(uint256(b) >> 96);
  }

  /**
   * @notice Inserts an element into a doubly linked list.
   * @param list A storage pointer to the underlying list.
   * @param key The key of the element to insert.
   * @param previousKey The key of the element that comes before the element to insert.
   * @param nextKey The key of the element that comes after the element to insert.
   */
  function insert(
    LinkedList.List storage list,
    address key,
    address previousKey,
    address nextKey
  ) public {
    list.insert(toBytes(key), toBytes(previousKey), toBytes(nextKey));
  }

  /**
   * @notice Inserts an element at the end of the doubly linked list.
   * @param list A storage pointer to the underlying list.
   * @param key The key of the element to insert.
   */
  function push(LinkedList.List storage list, address key) public {
    list.insert(toBytes(key), bytes32(0), list.tail);
  }

  /**
   * @notice Removes an element from the doubly linked list.
   * @param list A storage pointer to the underlying list.
   * @param key The key of the element to remove.
   */
  function remove(LinkedList.List storage list, address key) public {
    list.remove(toBytes(key));
  }

  /**
   * @notice Updates an element in the list.
   * @param list A storage pointer to the underlying list.
   * @param key The element key.
   * @param previousKey The key of the element that comes before the updated element.
   * @param nextKey The key of the element that comes after the updated element.
   */
  function update(
    LinkedList.List storage list,
    address key,
    address previousKey,
    address nextKey
  ) public {
    list.update(toBytes(key), toBytes(previousKey), toBytes(nextKey));
  }

  /**
   * @notice Returns whether or not a particular key is present in the sorted list.
   * @param list A storage pointer to the underlying list.
   * @param key The element key.
   * @return Whether or not the key is in the sorted list.
   */
  function contains(LinkedList.List storage list, address key) public view returns (bool) {
    return list.elements[toBytes(key)].exists;
  }

  /**
   * @notice Returns the N greatest elements of the list.
   * @param list A storage pointer to the underlying list.
   * @param n The number of elements to return.
   * @return The keys of the greatest elements.
   * @dev Reverts if n is greater than the number of elements in the list.
   */
  function headN(LinkedList.List storage list, uint256 n) public view returns (address[] memory) {
    bytes32[] memory byteKeys = list.headN(n);
    address[] memory keys = new address[](n);
    for (uint256 i = 0; i < n; i = i.add(1)) {
      keys[i] = toAddress(byteKeys[i]);
    }
    return keys;
  }

  /**
   * @notice Gets all element keys from the doubly linked list.
   * @param list A storage pointer to the underlying list.
   * @return All element keys from head to tail.
   */
  function getKeys(LinkedList.List storage list) public view returns (address[] memory) {
    return headN(list, list.numElements);
  }
}
        

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.5.13;

import "openzeppelin-solidity/contracts/math/SafeMath.sol";

/**
 * @title Maintains a doubly linked list keyed by bytes32.
 * @dev Following the `next` pointers will lead you to the head, rather than the tail.
 */
library LinkedList {
  using SafeMath for uint256;

  struct Element {
    bytes32 previousKey;
    bytes32 nextKey;
    bool exists;
  }

  struct List {
    bytes32 head;
    bytes32 tail;
    uint256 numElements;
    mapping(bytes32 => Element) elements;
  }

  /**
   * @notice Inserts an element into a doubly linked list.
   * @param list A storage pointer to the underlying list.
   * @param key The key of the element to insert.
   * @param previousKey The key of the element that comes before the element to insert.
   * @param nextKey The key of the element that comes after the element to insert.
   */
  function insert(
    List storage list,
    bytes32 key,
    bytes32 previousKey,
    bytes32 nextKey
  ) internal {
    require(key != bytes32(0), "Key must be defined");
    require(!contains(list, key), "Can't insert an existing element");
    require(previousKey != key && nextKey != key, "Key cannot be the same as previousKey or nextKey");

    Element storage element = list.elements[key];
    element.exists = true;

    if (list.numElements == 0) {
      list.tail = key;
      list.head = key;
    } else {
      require(previousKey != bytes32(0) || nextKey != bytes32(0), "Either previousKey or nextKey must be defined");

      element.previousKey = previousKey;
      element.nextKey = nextKey;

      if (previousKey != bytes32(0)) {
        require(contains(list, previousKey), "If previousKey is defined, it must exist in the list");
        Element storage previousElement = list.elements[previousKey];
        require(previousElement.nextKey == nextKey, "previousKey must be adjacent to nextKey");
        previousElement.nextKey = key;
      } else {
        list.tail = key;
      }

      if (nextKey != bytes32(0)) {
        require(contains(list, nextKey), "If nextKey is defined, it must exist in the list");
        Element storage nextElement = list.elements[nextKey];
        require(nextElement.previousKey == previousKey, "previousKey must be adjacent to nextKey");
        nextElement.previousKey = key;
      } else {
        list.head = key;
      }
    }

    list.numElements = list.numElements.add(1);
  }

  /**
   * @notice Inserts an element at the tail of the doubly linked list.
   * @param list A storage pointer to the underlying list.
   * @param key The key of the element to insert.
   */
  function push(List storage list, bytes32 key) internal {
    insert(list, key, bytes32(0), list.tail);
  }

  /**
   * @notice Removes an element from the doubly linked list.
   * @param list A storage pointer to the underlying list.
   * @param key The key of the element to remove.
   */
  function remove(List storage list, bytes32 key) internal {
    Element storage element = list.elements[key];
    require(key != bytes32(0) && contains(list, key), "key not in list");
    if (element.previousKey != bytes32(0)) {
      Element storage previousElement = list.elements[element.previousKey];
      previousElement.nextKey = element.nextKey;
    } else {
      list.tail = element.nextKey;
    }

    if (element.nextKey != bytes32(0)) {
      Element storage nextElement = list.elements[element.nextKey];
      nextElement.previousKey = element.previousKey;
    } else {
      list.head = element.previousKey;
    }

    delete list.elements[key];
    list.numElements = list.numElements.sub(1);
  }

  /**
   * @notice Updates an element in the list.
   * @param list A storage pointer to the underlying list.
   * @param key The element key.
   * @param previousKey The key of the element that comes before the updated element.
   * @param nextKey The key of the element that comes after the updated element.
   */
  function update(
    List storage list,
    bytes32 key,
    bytes32 previousKey,
    bytes32 nextKey
  ) internal {
    require(key != bytes32(0) && key != previousKey && key != nextKey && contains(list, key), "key on in list");
    remove(list, key);
    insert(list, key, previousKey, nextKey);
  }

  /**
   * @notice Returns whether or not a particular key is present in the sorted list.
   * @param list A storage pointer to the underlying list.
   * @param key The element key.
   * @return Whether or not the key is in the sorted list.
   */
  function contains(List storage list, bytes32 key) internal view returns (bool) {
    return list.elements[key].exists;
  }

  /**
   * @notice Returns the keys of the N elements at the head of the list.
   * @param list A storage pointer to the underlying list.
   * @param n The number of elements to return.
   * @return The keys of the N elements at the head of the list.
   * @dev Reverts if n is greater than the number of elements in the list.
   */
  function headN(List storage list, uint256 n) internal view returns (bytes32[] memory) {
    require(n <= list.numElements, "not enough elements");
    bytes32[] memory keys = new bytes32[](n);
    bytes32 key = list.head;
    for (uint256 i = 0; i < n; i = i.add(1)) {
      keys[i] = key;
      key = list.elements[key].previousKey;
    }
    return keys;
  }

  /**
   * @notice Gets all element keys from the doubly linked list.
   * @param list A storage pointer to the underlying list.
   * @return All element keys from head to tail.
   */
  function getKeys(List storage list) internal view returns (bytes32[] memory) {
    return headN(list, list.numElements);
  }
}
          

pragma solidity ^0.5.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot overflow.
     */
    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;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    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;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}