react-native-reanimated/lib/module/reanimated2/shareables.js

More powerful alternative to Animated library for React Native.

import NativeReanimatedModule from './NativeReanimated';
import { shouldBeUseWeb } from './PlatformChecker';
import { registerWorkletStackDetails } from './errors'; // for web/chrome debugger/jest environments this file provides a stub implementation
// where no shareable references are used. Instead, the objects themselves are used
// instead of shareable references, because of the fact that we don't have to deal with
// runnning the code on separate VMs.

const USE_STUB_IMPLEMENTATION = shouldBeUseWeb();

const _shareableCache = new WeakMap(); // the below symbol is used to represent a mapping from the value to itself
// this is used to allow for a converted shareable to be passed to makeShareableClone


const _shareableFlag = Symbol('shareable flag');

const MAGIC_KEY = 'REANIMATED_MAGIC_KEY';

function isHostObject(value) {
  // We could use JSI to determine whether an object is a host object, however
  // the below workaround works well and is way faster than an additional JSI call.
  // We use the fact that host objects have broken implementation of `hasOwnProperty`
  // and hence return true for all `in` checks regardless of the key we ask for.
  return MAGIC_KEY in value;
}

export function registerShareableMapping(shareable, shareableRef) {
  if (USE_STUB_IMPLEMENTATION) {
    return;
  }

  _shareableCache.set(shareable, shareableRef || _shareableFlag);
}
export function makeShareableCloneRecursive(value) {
  let shouldPersistRemote = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : false;

  if (USE_STUB_IMPLEMENTATION) {
    return value;
  } // This one actually may be worth to be moved to c++, we also need similar logic to run on the UI thread


  const type = typeof value;

  if ((type === 'object' || type === 'function') && value !== null) {
    const cached = _shareableCache.get(value);

    if (cached === _shareableFlag) {
      return value;
    } else if (cached !== undefined) {
      return cached;
    } else {
      let toAdapt;

      if (Array.isArray(value)) {
        toAdapt = value.map(element => makeShareableCloneRecursive(element));
      } else if (type === 'function' && value.__workletHash === undefined) {
        // this is a remote function
        toAdapt = value;
      } else if (isHostObject(value)) {
        // for host objects we pass the reference to the object as shareable and
        // then recreate new host object wrapping the same instance on the UI thread.
        // there is no point of iterating over keys as we do for regular objects.
        toAdapt = value;
      } else {
        toAdapt = {};

        if (value.__workletHash !== undefined) {
          // we are converting a worklet
          if (__DEV__) {
            registerWorkletStackDetails(value.__workletHash, value.__stackDetails);
            delete value.__stackDetails;
          } // to save on transferring static __initData field of worklet structure
          // we request shareable value to persist its UI counterpart. This means
          // that the __initData field that contains long strings represeting the
          // worklet code, source map, and location, will always be
          // serialized/deserialized once.


          toAdapt.__initData = makeShareableCloneRecursive(value.__initData, true);
          delete value.__initData;
        }

        for (const [key, element] of Object.entries(value)) {
          toAdapt[key] = makeShareableCloneRecursive(element);
        }
      }

      if (__DEV__) {
        // we freeze objects that are transformed to shareable. This should help
        // detect issues when someone modifies data after it's been converted to
        // shareable. Meaning that they may be doing a faulty assumption in their
        // code expecting that the updates are going to automatically populate to
        // the object sent to the UI thread. If the user really wants some objects
        // to be mutable they should use shared values instead.
        Object.freeze(value);
      }

      const adopted = NativeReanimatedModule.makeShareableClone(toAdapt, shouldPersistRemote);

      _shareableCache.set(value, adopted);

      _shareableCache.set(adopted, _shareableFlag);

      return adopted;
    }
  }

  return NativeReanimatedModule.makeShareableClone(value, shouldPersistRemote);
}
export function makeShareableCloneOnUIRecursive(value) {
  'worklet';

  if (USE_STUB_IMPLEMENTATION) {
    // @ts-ignore web is an interesting place where we don't run a secondary VM on the UI thread
    // see more details in the comment where USE_STUB_IMPLEMENTATION is defined.
    return value;
  }

  function cloneRecursive(value) {
    const type = typeof value;

    if ((type === 'object' || type === 'function') && value !== null) {
      let toAdapt;

      if (Array.isArray(value)) {
        toAdapt = value.map(element => cloneRecursive(element));
      } else {
        toAdapt = {};

        for (const [key, element] of Object.entries(value)) {
          toAdapt[key] = cloneRecursive(element);
        }
      }

      if (__DEV__) {
        // See the reasoning behind freezing in the other comment above.
        Object.freeze(value);
      }

      return _makeShareableClone(toAdapt);
    }

    return _makeShareableClone(value);
  }

  return cloneRecursive(value);
}
export function makeShareable(value) {
  if (USE_STUB_IMPLEMENTATION) {
    return value;
  }

  const handle = makeShareableCloneRecursive({
    __init: () => {
      'worklet';

      return value;
    }
  });
  registerShareableMapping(value, handle);
  return value;
}
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