recoil/cjs/caches/Recoil_cacheWithValueEquality.js.flow

Recoil - A state management library for React

/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * Cache implementation with value equality for keys
 *
 * @emails oncall+recoil
 * @flow strict
 * @format
 */
'use strict';

import type { CacheImplementation } from './Recoil_Cache';

const stableStringify = require('../util/Recoil_stableStringify'); // If we do profile and find the key equality check is expensive,
// we could always try to optimize..  Something that comes to mind is having
// each check assign an incrementing index to each reference that maps to the
// value equivalency.  Then, if an object already has an index, the comparison
// check/lookup would be trivial and the string serialization would only need
// to be done once per object instance.  Just a thought..
// Cache implementation to use value equality for keys instead of the default
// reference equality.  This allows different instances of dependency values to
// be used.  Normally this is not needed, as dependent atoms/selectors will
// themselves be cached and always return the same instance.  However, if
// different params or upstream values for those dependencies could produce
// equivalent values or they have a custom cache implementation, then this
// implementation may be needed.  The downside with this approach is that it
// takes longer to compute the value equivalence vs simple reference equality.


declare function cacheWithValueEquality<T>(): CacheImplementation<T>;
module.exports = cacheWithValueEquality;