react-native-reanimated/src/reanimated2/shareableMappingCache.ts

'use strict';
import { shouldBeUseWeb } from './PlatformChecker';
import type { ShareableRef } from './commonTypes';

const SHOULD_BE_USE_WEB = shouldBeUseWeb();

/**
 * This symbol is used to represent a mapping from the value to itself.
 *
 * It's used to prevent converting a shareable that's already converted -
 * for example a Shared Value that's in worklet's closure.
 **/
export const shareableMappingFlag = Symbol('shareable flag');

/*
During a fast refresh, React holds the same instance of a Mutable
(that's guaranteed by `useRef`) but `shareableCache` gets regenerated and thus
becoming empty. This happens when editing the file that contains the definition of this cache.

Because of it, `makeShareableCloneRecursive` can't find given mapping
in `shareableCache` for the Mutable and tries to clone it as if it was a regular JS object.
During cloning we use `Object.entries` to iterate over the keys which throws an error on accessing `_value`.
For convenience we moved this cache to a separate file so it doesn't scare us with red squiggles.
*/

const cache = SHOULD_BE_USE_WEB
  ? null
  : new WeakMap<object, ShareableRef | symbol>();

export const shareableMappingCache = SHOULD_BE_USE_WEB
  ? {
      set() {
        // NOOP
      },
      get() {
        return null;
      },
    }
  : {
      set(shareable: object, shareableRef?: ShareableRef): void {
        cache!.set(shareable, shareableRef || shareableMappingFlag);
      },
      get: cache!.get.bind(cache),
    };