createReactNoop.js

/**
 * Copyright (c) 2013-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow
 */

/**
 * This is a renderer of React that doesn't have a render target output.
 * It is useful to demonstrate the internals of the reconciler in isolation
 * and for testing semantics of reconciliation separate from the host
 * environment.
 */

import type {Fiber} from 'react-reconciler/src/ReactFiber';
import type {UpdateQueue} from 'react-reconciler/src/ReactUpdateQueue';
import type {ReactNodeList} from 'shared/ReactTypes';

import * as ReactPortal from 'shared/ReactPortal';
import emptyObject from 'fbjs/lib/emptyObject';
import expect from 'expect';

type Container = {rootID: string, children: Array<Instance | TextInstance>};
type Props = {prop: any, hidden?: boolean, children?: mixed};
type Instance = {|
  type: string,
  id: number,
  children: Array<Instance | TextInstance>,
  prop: any,
|};
type TextInstance = {|text: string, id: number|};

function createReactNoop(reconciler: Function, useMutation: boolean) {
  const UPDATE_SIGNAL = {};
  let scheduledCallback = null;

  let instanceCounter = 0;
  let failInBeginPhase = false;

  function appendChild(
    parentInstance: Instance | Container,
    child: Instance | TextInstance,
  ): void {
    const index = parentInstance.children.indexOf(child);
    if (index !== -1) {
      parentInstance.children.splice(index, 1);
    }
    parentInstance.children.push(child);
  }

  function insertBefore(
    parentInstance: Instance | Container,
    child: Instance | TextInstance,
    beforeChild: Instance | TextInstance,
  ): void {
    const index = parentInstance.children.indexOf(child);
    if (index !== -1) {
      parentInstance.children.splice(index, 1);
    }
    const beforeIndex = parentInstance.children.indexOf(beforeChild);
    if (beforeIndex === -1) {
      throw new Error('This child does not exist.');
    }
    parentInstance.children.splice(beforeIndex, 0, child);
  }

  function removeChild(
    parentInstance: Instance | Container,
    child: Instance | TextInstance,
  ): void {
    const index = parentInstance.children.indexOf(child);
    if (index === -1) {
      throw new Error('This child does not exist.');
    }
    parentInstance.children.splice(index, 1);
  }

  let elapsedTimeInMs = 0;

  const sharedHostConfig = {
    getRootHostContext() {
      if (failInBeginPhase) {
        throw new Error('Error in host config.');
      }
      return emptyObject;
    },

    getChildHostContext() {
      return emptyObject;
    },

    getPublicInstance(instance) {
      return instance;
    },

    createInstance(type: string, props: Props): Instance {
      const inst = {
        id: instanceCounter++,
        type: type,
        children: [],
        prop: props.prop,
      };
      // Hide from unit tests
      Object.defineProperty(inst, 'id', {value: inst.id, enumerable: false});
      return inst;
    },

    appendInitialChild(
      parentInstance: Instance,
      child: Instance | TextInstance,
    ): void {
      parentInstance.children.push(child);
    },

    finalizeInitialChildren(
      domElement: Instance,
      type: string,
      props: Props,
    ): boolean {
      return false;
    },

    prepareUpdate(
      instance: Instance,
      type: string,
      oldProps: Props,
      newProps: Props,
    ): null | {} {
      if (oldProps === null) {
        throw new Error('Should have old props');
      }
      if (newProps === null) {
        throw new Error('Should have new props');
      }
      return UPDATE_SIGNAL;
    },

    shouldSetTextContent(type: string, props: Props): boolean {
      return (
        typeof props.children === 'string' || typeof props.children === 'number'
      );
    },

    shouldDeprioritizeSubtree(type: string, props: Props): boolean {
      return !!props.hidden;
    },

    createTextInstance(
      text: string,
      rootContainerInstance: Container,
      hostContext: Object,
      internalInstanceHandle: Object,
    ): TextInstance {
      const inst = {text: text, id: instanceCounter++};
      // Hide from unit tests
      Object.defineProperty(inst, 'id', {value: inst.id, enumerable: false});
      return inst;
    },

    scheduleDeferredCallback(callback) {
      if (scheduledCallback) {
        throw new Error(
          'Scheduling a callback twice is excessive. Instead, keep track of ' +
            'whether the callback has already been scheduled.',
        );
      }
      scheduledCallback = callback;
      return 0;
    },

    cancelDeferredCallback() {
      if (scheduledCallback === null) {
        throw new Error('No callback is scheduled.');
      }
      scheduledCallback = null;
    },

    prepareForCommit(): void {},

    resetAfterCommit(): void {},

    now(): number {
      return elapsedTimeInMs;
    },

    isPrimaryRenderer: true,
    supportsHydration: false,
  };

  const hostConfig = useMutation
    ? {
        ...sharedHostConfig,

        supportsMutation: true,
        supportsPersistence: false,

        commitMount(instance: Instance, type: string, newProps: Props): void {
          // Noop
        },

        commitUpdate(
          instance: Instance,
          updatePayload: Object,
          type: string,
          oldProps: Props,
          newProps: Props,
        ): void {
          if (oldProps === null) {
            throw new Error('Should have old props');
          }
          instance.prop = newProps.prop;
        },

        commitTextUpdate(
          textInstance: TextInstance,
          oldText: string,
          newText: string,
        ): void {
          textInstance.text = newText;
        },

        appendChild: appendChild,
        appendChildToContainer: appendChild,
        insertBefore: insertBefore,
        insertInContainerBefore: insertBefore,
        removeChild: removeChild,
        removeChildFromContainer: removeChild,

        resetTextContent(instance: Instance): void {},
      }
    : {
        ...sharedHostConfig,
        supportsMutation: false,
        supportsPersistence: true,

        cloneInstance(
          instance: Instance,
          updatePayload: null | Object,
          type: string,
          oldProps: Props,
          newProps: Props,
          internalInstanceHandle: Object,
          keepChildren: boolean,
          recyclableInstance: null | Instance,
        ): Instance {
          const clone = {
            id: instance.id,
            type: type,
            children: keepChildren ? instance.children : [],
            prop: newProps.prop,
          };
          Object.defineProperty(clone, 'id', {
            value: clone.id,
            enumerable: false,
          });
          return clone;
        },

        createContainerChildSet(
          container: Container,
        ): Array<Instance | TextInstance> {
          return [];
        },

        appendChildToContainerChildSet(
          childSet: Array<Instance | TextInstance>,
          child: Instance | TextInstance,
        ): void {
          childSet.push(child);
        },

        finalizeContainerChildren(
          container: Container,
          newChildren: Array<Instance | TextInstance>,
        ): void {},

        replaceContainerChildren(
          container: Container,
          newChildren: Array<Instance | TextInstance>,
        ): void {
          container.children = newChildren;
        },
      };

  const NoopRenderer = reconciler(hostConfig);

  const rootContainers = new Map();
  const roots = new Map();
  const DEFAULT_ROOT_ID = '<default>';

  let yieldedValues = null;

  let unitsRemaining;

  function* flushUnitsOfWork(n: number): Generator<Array<mixed>, void, void> {
    let didStop = false;
    while (!didStop && scheduledCallback !== null) {
      let cb = scheduledCallback;
      scheduledCallback = null;
      unitsRemaining = n;
      cb({
        timeRemaining() {
          if (yieldedValues !== null) {
            return 0;
          }
          if (unitsRemaining-- > 0) {
            return 999;
          }
          didStop = true;
          return 0;
        },
        // React's scheduler has its own way of keeping track of expired
        // work and doesn't read this, so don't bother setting it to the
        // correct value.
        didTimeout: false,
      });

      if (yieldedValues !== null) {
        const values = yieldedValues;
        yieldedValues = null;
        yield values;
      }
    }
  }

  const ReactNoop = {
    getChildren(rootID: string = DEFAULT_ROOT_ID) {
      const container = rootContainers.get(rootID);
      if (container) {
        return container.children;
      } else {
        return null;
      }
    },

    createPortal(
      children: ReactNodeList,
      container: Container,
      key: ?string = null,
    ) {
      return ReactPortal.createPortal(children, container, null, key);
    },

    // Shortcut for testing a single root
    render(element: React$Element<any>, callback: ?Function) {
      ReactNoop.renderToRootWithID(element, DEFAULT_ROOT_ID, callback);
    },

    renderToRootWithID(
      element: React$Element<any>,
      rootID: string,
      callback: ?Function,
    ) {
      let root = roots.get(rootID);
      if (!root) {
        const container = {rootID: rootID, children: []};
        rootContainers.set(rootID, container);
        root = NoopRenderer.createContainer(container, true, false);
        roots.set(rootID, root);
      }
      NoopRenderer.updateContainer(element, root, null, callback);
    },

    unmountRootWithID(rootID: string) {
      const root = roots.get(rootID);
      if (root) {
        NoopRenderer.updateContainer(null, root, null, () => {
          roots.delete(rootID);
          rootContainers.delete(rootID);
        });
      }
    },

    findInstance(
      componentOrElement: Element | ?React$Component<any, any>,
    ): null | Instance | TextInstance {
      if (componentOrElement == null) {
        return null;
      }
      // Unsound duck typing.
      const component = (componentOrElement: any);
      if (typeof component.id === 'number') {
        return component;
      }
      return NoopRenderer.findHostInstance(component);
    },

    flushDeferredPri(timeout: number = Infinity): Array<mixed> {
      // The legacy version of this function decremented the timeout before
      // returning the new time.
      // TODO: Convert tests to use flushUnitsOfWork or flushAndYield instead.
      const n = timeout / 5 - 1;

      let values = [];
      // eslint-disable-next-line no-for-of-loops/no-for-of-loops
      for (const value of flushUnitsOfWork(n)) {
        values.push(...value);
      }
      return values;
    },

    flush(): Array<mixed> {
      return ReactNoop.flushUnitsOfWork(Infinity);
    },

    flushAndYield(
      unitsOfWork: number = Infinity,
    ): Generator<Array<mixed>, void, void> {
      return flushUnitsOfWork(unitsOfWork);
    },

    flushUnitsOfWork(n: number): Array<mixed> {
      let values = yieldedValues || [];
      yieldedValues = null;
      // eslint-disable-next-line no-for-of-loops/no-for-of-loops
      for (const value of flushUnitsOfWork(n)) {
        values.push(...value);
      }
      return values;
    },

    flushThrough(expected: Array<mixed>): void {
      let actual = [];
      if (expected.length !== 0) {
        // eslint-disable-next-line no-for-of-loops/no-for-of-loops
        for (const value of flushUnitsOfWork(Infinity)) {
          actual.push(...value);
          if (actual.length >= expected.length) {
            break;
          }
        }
      }
      expect(actual).toEqual(expected);
    },

    expire(ms: number): void {
      elapsedTimeInMs += ms;
    },

    flushExpired(): Array<mixed> {
      return ReactNoop.flushUnitsOfWork(0);
    },

    yield(value: mixed) {
      if (yieldedValues === null) {
        yieldedValues = [value];
      } else {
        yieldedValues.push(value);
      }
    },

    clearYields() {
      const values = yieldedValues;
      yieldedValues = null;
      return values;
    },

    hasScheduledCallback() {
      return !!scheduledCallback;
    },

    batchedUpdates: NoopRenderer.batchedUpdates,

    deferredUpdates: NoopRenderer.deferredUpdates,

    unbatchedUpdates: NoopRenderer.unbatchedUpdates,

    interactiveUpdates: NoopRenderer.interactiveUpdates,

    flushSync(fn: () => mixed) {
      yieldedValues = [];
      NoopRenderer.flushSync(fn);
      return yieldedValues;
    },

    // Logs the current state of the tree.
    dumpTree(rootID: string = DEFAULT_ROOT_ID) {
      const root = roots.get(rootID);
      const rootContainer = rootContainers.get(rootID);
      if (!root || !rootContainer) {
        console.log('Nothing rendered yet.');
        return;
      }

      let bufferedLog = [];
      function log(...args) {
        bufferedLog.push(...args, '\n');
      }

      function logHostInstances(
        children: Array<Instance | TextInstance>,
        depth,
      ) {
        for (let i = 0; i < children.length; i++) {
          const child = children[i];
          const indent = '  '.repeat(depth);
          if (typeof child.text === 'string') {
            log(indent + '- ' + child.text);
          } else {
            // $FlowFixMe - The child should've been refined now.
            log(indent + '- ' + child.type + '#' + child.id);
            // $FlowFixMe - The child should've been refined now.
            logHostInstances(child.children, depth + 1);
          }
        }
      }
      function logContainer(container: Container, depth) {
        log('  '.repeat(depth) + '- [root#' + container.rootID + ']');
        logHostInstances(container.children, depth + 1);
      }

      function logUpdateQueue(updateQueue: UpdateQueue<mixed>, depth) {
        log('  '.repeat(depth + 1) + 'QUEUED UPDATES');
        const firstUpdate = updateQueue.firstUpdate;
        if (!firstUpdate) {
          return;
        }

        log(
          '  '.repeat(depth + 1) + '~',
          '[' + firstUpdate.expirationTime + ']',
        );
        while (firstUpdate.next) {
          log(
            '  '.repeat(depth + 1) + '~',
            '[' + firstUpdate.expirationTime + ']',
          );
        }
      }

      function logFiber(fiber: Fiber, depth) {
        log(
          '  '.repeat(depth) +
            '- ' +
            // need to explicitly coerce Symbol to a string
            (fiber.type ? fiber.type.name || fiber.type.toString() : '[root]'),
          '[' + fiber.expirationTime + (fiber.pendingProps ? '*' : '') + ']',
        );
        if (fiber.updateQueue) {
          logUpdateQueue(fiber.updateQueue, depth);
        }
        // const childInProgress = fiber.progressedChild;
        // if (childInProgress && childInProgress !== fiber.child) {
        //   log(
        //     '  '.repeat(depth + 1) + 'IN PROGRESS: ' + fiber.pendingWorkPriority,
        //   );
        //   logFiber(childInProgress, depth + 1);
        //   if (fiber.child) {
        //     log('  '.repeat(depth + 1) + 'CURRENT');
        //   }
        // } else if (fiber.child && fiber.updateQueue) {
        //   log('  '.repeat(depth + 1) + 'CHILDREN');
        // }
        if (fiber.child) {
          logFiber(fiber.child, depth + 1);
        }
        if (fiber.sibling) {
          logFiber(fiber.sibling, depth);
        }
      }

      log('HOST INSTANCES:');
      logContainer(rootContainer, 0);
      log('FIBERS:');
      logFiber(root.current, 0);

      console.log(...bufferedLog);
    },

    simulateErrorInHostConfig(fn: () => void) {
      failInBeginPhase = true;
      try {
        fn();
      } finally {
        failInBeginPhase = false;
      }
    },
  };

  return ReactNoop;
}

export default createReactNoop;