// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
/**
* @dev Library for managing an enumerable variant of Solidity's
* https://solidity.readthedocs.io/en/latest/types.html#mapping-types[`mapping`]
* type.
*
* Maps have the following properties:
*
* - Entries are added, removed, and checked for existence in constant time
* (O(1)).
* - Entries are enumerated in O(n). No guarantees are made on the ordering.
*
* ```
* contract Example {
* // Add the library methods
* using EnumerableMap for EnumerableMap.UintToAddressMap;
*
* // Declare a set state variable
* EnumerableMap.UintToAddressMap private myMap;
* }
* ```
*
* As of v3.0.0, only maps of type `uint256 -> address` (`UintToAddressMap`) are
* supported.
*/
library EnumerableMap {
// To implement this library for multiple types with as little code
// repetition as possible, we write it in terms of a generic Map type with
// bytes32 keys and values.
// The Map implementation uses private functions, and user-facing
// implementations (such as Uint256ToAddressMap) are just wrappers around
// the underlying Map.
// This means that we can only create new EnumerableMaps for types that fit
// in bytes32.
struct MapEntry {
bytes32 _key;
bytes32 _value;
}
struct Map {
// Storage of map keys and values
MapEntry[] _entries;
// Position of the entry defined by a key in the `entries` array, plus 1
// because index 0 means a key is not in the map.
mapping (bytes32 => uint256) _indexes;
}
/**
* @dev Adds a key-value pair to a map, or updates the value for an existing
* key. O(1).
*
* Returns true if the key was added to the map, that is if it was not
* already present.
*/
function _set(Map storage map, bytes32 key, bytes32 value) private returns (bool) {
// We read and store the key's index to prevent multiple reads from the same storage slot
uint256 keyIndex = map._indexes[key];
if (keyIndex == 0) { // Equivalent to !contains(map, key)
map._entries.push(MapEntry({ _key: key, _value: value }));
// The entry is stored at length-1, but we add 1 to all indexes
// and use 0 as a sentinel value
map._indexes[key] = map._entries.length;
return true;
} else {
map._entries[keyIndex - 1]._value = value;
return false;
}
}
/**
* @dev Removes a key-value pair from a map. O(1).
*
* Returns true if the key was removed from the map, that is if it was present.
*/
function _remove(Map storage map, bytes32 key) private returns (bool) {
// We read and store the key's index to prevent multiple reads from the same storage slot
uint256 keyIndex = map._indexes[key];
if (keyIndex != 0) { // Equivalent to contains(map, key)
// To delete a key-value pair from the _entries array in O(1), we swap the entry to delete with the last one
// in the array, and then remove the last entry (sometimes called as 'swap and pop').
// This modifies the order of the array, as noted in {at}.
uint256 toDeleteIndex = keyIndex - 1;
uint256 lastIndex = map._entries.length - 1;
// When the entry 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.
MapEntry storage lastEntry = map._entries[lastIndex];
// Move the last entry to the index where the entry to delete is
map._entries[toDeleteIndex] = lastEntry;
// Update the index for the moved entry
map._indexes[lastEntry._key] = toDeleteIndex + 1; // All indexes are 1-based
// Delete the slot where the moved entry was stored
map._entries.pop();
// Delete the index for the deleted slot
delete map._indexes[key];
return true;
} else {
return false;
}
}
/**
* @dev Returns true if the key is in the map. O(1).
*/
function _contains(Map storage map, bytes32 key) private view returns (bool) {
return map._indexes[key] != 0;
}
/**
* @dev Returns the number of key-value pairs in the map. O(1).
*/
function _length(Map storage map) private view returns (uint256) {
return map._entries.length;
}
/**
* @dev Returns the key-value pair stored at position `index` in the map. O(1).
*
* Note that there are no guarantees on the ordering of entries inside the
* array, and it may change when more entries are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function _at(Map storage map, uint256 index) private view returns (bytes32, bytes32) {
require(map._entries.length > index, "EnumerableMap: index out of bounds");
MapEntry storage entry = map._entries[index];
return (entry._key, entry._value);
}
/**
* @dev Tries to returns the value associated with `key`. O(1).
* Does not revert if `key` is not in the map.
*/
function _tryGet(Map storage map, bytes32 key) private view returns (bool, bytes32) {
uint256 keyIndex = map._indexes[key];
if (keyIndex == 0) return (false, 0); // Equivalent to contains(map, key)
return (true, map._entries[keyIndex - 1]._value); // All indexes are 1-based
}
/**
* @dev Returns the value associated with `key`. O(1).
*
* Requirements:
*
* - `key` must be in the map.
*/
function _get(Map storage map, bytes32 key) private view returns (bytes32) {
uint256 keyIndex = map._indexes[key];
require(keyIndex != 0, "EnumerableMap: nonexistent key"); // Equivalent to contains(map, key)
return map._entries[keyIndex - 1]._value; // All indexes are 1-based
}
/**
* @dev Same as {_get}, with a custom error message when `key` is not in the map.
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {_tryGet}.
*/
function _get(Map storage map, bytes32 key, string memory errorMessage) private view returns (bytes32) {
uint256 keyIndex = map._indexes[key];
require(keyIndex != 0, errorMessage); // Equivalent to contains(map, key)
return map._entries[keyIndex - 1]._value; // All indexes are 1-based
}
// UintToAddressMap
struct UintToAddressMap {
Map _inner;
}
/**
* @dev Adds a key-value pair to a map, or updates the value for an existing
* key. O(1).
*
* Returns true if the key was added to the map, that is if it was not
* already present.
*/
function set(UintToAddressMap storage map, uint256 key, address value) internal returns (bool) {
return _set(map._inner, bytes32(key), bytes32(uint256(uint160(value))));
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the key was removed from the map, that is if it was present.
*/
function remove(UintToAddressMap storage map, uint256 key) internal returns (bool) {
return _remove(map._inner, bytes32(key));
}
/**
* @dev Returns true if the key is in the map. O(1).
*/
function contains(UintToAddressMap storage map, uint256 key) internal view returns (bool) {
return _contains(map._inner, bytes32(key));
}
/**
* @dev Returns the number of elements in the map. O(1).
*/
function length(UintToAddressMap storage map) internal view returns (uint256) {
return _length(map._inner);
}
/**
* @dev Returns the element 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(UintToAddressMap storage map, uint256 index) internal view returns (uint256, address) {
(bytes32 key, bytes32 value) = _at(map._inner, index);
return (uint256(key), address(uint160(uint256(value))));
}
/**
* @dev Tries to returns the value associated with `key`. O(1).
* Does not revert if `key` is not in the map.
*
* _Available since v3.4._
*/
function tryGet(UintToAddressMap storage map, uint256 key) internal view returns (bool, address) {
(bool success, bytes32 value) = _tryGet(map._inner, bytes32(key));
return (success, address(uint160(uint256(value))));
}
/**
* @dev Returns the value associated with `key`. O(1).
*
* Requirements:
*
* - `key` must be in the map.
*/
function get(UintToAddressMap storage map, uint256 key) internal view returns (address) {
return address(uint160(uint256(_get(map._inner, bytes32(key)))));
}
/**
* @dev Same as {get}, with a custom error message when `key` is not in the map.
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {tryGet}.
*/
function get(UintToAddressMap storage map, uint256 key, string memory errorMessage) internal view returns (address) {
return address(uint160(uint256(_get(map._inner, bytes32(key), errorMessage))));
}
}