recoil/cjs/recoil_values/Recoil_selectorFamily.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.
 *
 * @emails oncall+recoil
 * @flow strict-local
 * @format
 */
'use strict';

import type {Loadable} from '../adt/Recoil_Loadable';
import type {WrappedValue} from '../adt/Recoil_Wrapper';
import type {
  CachePolicy,
  CachePolicyWithoutEviction,
} from '../caches/Recoil_CachePolicy';
import type {DefaultValue} from '../core/Recoil_Node';
import type {
  RecoilState,
  RecoilValue,
  RecoilValueReadOnly,
} from '../core/Recoil_RecoilValue';
import type {RetainedBy} from '../core/Recoil_RetainedBy';
import type {GetCallback} from '../recoil_values/Recoil_selector';
import type {
  GetRecoilValue,
  ResetRecoilState,
  SetRecoilState,
} from './Recoil_callbackTypes';

const cacheFromPolicy = require('../caches/Recoil_cacheFromPolicy');
const {setConfigDeletionHandler} = require('../core/Recoil_Node');
const selector = require('./Recoil_selector');
const err = require('recoil-shared/util/Recoil_err');
const stableStringify = require('recoil-shared/util/Recoil_stableStringify');

// Keep in mind the parameter needs to be serializable as a cahche key
// using Recoil_stableStringify
type Primitive = void | null | boolean | number | string;
interface HasToJSON {
  toJSON(): Parameter;
}
export type Parameter =
  | Primitive
  | HasToJSON
  | $ReadOnlySet<Parameter>
  | $ReadOnlyMap<Parameter, Parameter>
  | $ReadOnlyArray<Parameter>
  | $ReadOnly<{...}>;
// | $ReadOnly<{[string]: Parameter}>; // TODO Better enforce object is serializable

type BaseSelectorFamilyOptions<P: Parameter> = $ReadOnly<{
  key: string,
  cachePolicyForParams_UNSTABLE?: CachePolicyWithoutEviction,
  cachePolicy_UNSTABLE?: CachePolicy,
  dangerouslyAllowMutability?: boolean,
  retainedBy_UNSTABLE?: RetainedBy | (P => RetainedBy),
}>;

export type ReadOnlySelectorFamilyOptions<T, P: Parameter> = $ReadOnly<{
  ...BaseSelectorFamilyOptions<P>,
  get: P => ({
    get: GetRecoilValue,
    getCallback: GetCallback<T>,
  }) => Promise<T> | Loadable<T> | WrappedValue<T> | RecoilValue<T> | T,
}>;

export type ReadWriteSelectorFamilyOptions<T, P: Parameter> = $ReadOnly<{
  ...ReadOnlySelectorFamilyOptions<T, P>,
  set: P => (
    {set: SetRecoilState, get: GetRecoilValue, reset: ResetRecoilState},
    newValue: T | DefaultValue,
  ) => void,
}>;

export type SelectorFamilyOptions<T, P> =
  | ReadOnlySelectorFamilyOptions<T, P>
  | ReadWriteSelectorFamilyOptions<T, P>;

// Add a unique index to each selector in case the cache implementation allows
// duplicate keys based on equivalent stringified parameters
let nextIndex = 0;

/* eslint-disable no-redeclare */
declare function selectorFamily<T, Params: Parameter>(
  options: ReadOnlySelectorFamilyOptions<T, Params>,
): Params => RecoilValueReadOnly<T>;
declare function selectorFamily<T, Params: Parameter>(
  options: ReadWriteSelectorFamilyOptions<T, Params>,
): Params => RecoilState<T>;

// Return a function that returns members of a family of selectors of the same type
// E.g.,
//
// const s = selectorFamily(...);
// s({a: 1}) => a selector
// s({a: 2}) => a different selector
//
// By default, the selectors are distinguished by distinct values of the
// parameter based on value equality, not reference equality.  This allows using
// object literals or other equivalent objects at callsites to not create
// duplicate cache entries.  This behavior may be overridden with the
// cacheImplementationForParams option.
function selectorFamily<T, Params: Parameter>(
  options:
    | ReadOnlySelectorFamilyOptions<T, Params>
    | ReadWriteSelectorFamilyOptions<T, Params>,
): Params => RecoilValue<T> {
  const selectorCache = cacheFromPolicy<
    Params,
    RecoilState<T> | RecoilValueReadOnly<T>,
  >({
    equality: options.cachePolicyForParams_UNSTABLE?.equality ?? 'value',
    eviction: 'keep-all',
  });

  return (params: Params) => {
    // Throw an error with selector key so that it is clear which
    // selector is causing an error
    let cachedSelector;
    try {
      cachedSelector = selectorCache.get(params);
    } catch (error) {
      throw err(
        `Problem with cache lookup for selector ${options.key}: ${error.message}`,
      );
    }
    if (cachedSelector != null) {
      return cachedSelector;
    }

    const myKey = `${options.key}__selectorFamily/${
      stableStringify(params, {
        // It is possible to use functions in parameters if the user uses
        // a cache with reference equality thanks to the incrementing index.
        allowFunctions: true,
      }) ?? 'void'
    }/${nextIndex++}`; // Append index in case values serialize to the same key string

    const myGet = callbacks => options.get(params)(callbacks);
    const myCachePolicy = options.cachePolicy_UNSTABLE;

    const retainedBy =
      typeof options.retainedBy_UNSTABLE === 'function'
        ? options.retainedBy_UNSTABLE(params)
        : options.retainedBy_UNSTABLE;

    let newSelector;
    if (options.set != null) {
      const set = options.set;
      const mySet = (callbacks, newValue) => set(params)(callbacks, newValue);
      newSelector = selector<T>({
        key: myKey,
        get: myGet,
        set: mySet,
        cachePolicy_UNSTABLE: myCachePolicy,
        dangerouslyAllowMutability: options.dangerouslyAllowMutability,
        retainedBy_UNSTABLE: retainedBy,
      });
    } else {
      newSelector = selector<T>({
        key: myKey,
        get: myGet,
        cachePolicy_UNSTABLE: myCachePolicy,
        dangerouslyAllowMutability: options.dangerouslyAllowMutability,
        retainedBy_UNSTABLE: retainedBy,
      });
    }

    selectorCache.set(params, newSelector);

    setConfigDeletionHandler(newSelector.key, () => {
      selectorCache.delete(params);
    });

    return newSelector;
  };
}
/* eslint-enable no-redeclare */

module.exports = selectorFamily;