ReactShallowRenderer.js

/**
 * 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.
 *
 *
 */

import React from 'react';
import {isForwardRef, isMemo, ForwardRef} from 'react-is';
import describeComponentFrame from './shared/describeComponentFrame';
import getComponentName from './shared/getComponentName';
import shallowEqual from './shared/shallowEqual';
import checkPropTypes from './shared/checkPropTypes';
import ReactSharedInternals from './shared/ReactSharedInternals';
import {error} from './shared/consoleWithStackDev';
import is from './shared/objectIs';

const {ReactCurrentDispatcher, ReactDebugCurrentFrame} = ReactSharedInternals;

const RE_RENDER_LIMIT = 25;

const emptyObject = {};
if (process.env.NODE_ENV !== 'production') {
  Object.freeze(emptyObject);
}

// In DEV, this is the name of the currently executing primitive hook
let currentHookNameInDev;

function areHookInputsEqual(nextDeps, prevDeps) {
  if (prevDeps === null) {
    if (process.env.NODE_ENV !== 'production') {
      error(
        '%s received a final argument during this render, but not during ' +
          'the previous render. Even though the final argument is optional, ' +
          'its type cannot change between renders.',
        currentHookNameInDev,
      );
    }
    return false;
  }

  if (process.env.NODE_ENV !== 'production') {
    // Don't bother comparing lengths in prod because these arrays should be
    // passed inline.
    if (nextDeps.length !== prevDeps.length) {
      error(
        'The final argument passed to %s changed size between renders. The ' +
          'order and size of this array must remain constant.\n\n' +
          'Previous: %s\n' +
          'Incoming: %s',
        currentHookNameInDev,
        `[${nextDeps.join(', ')}]`,
        `[${prevDeps.join(', ')}]`,
      );
    }
  }
  for (let i = 0; i < prevDeps.length && i < nextDeps.length; i++) {
    if (is(nextDeps[i], prevDeps[i])) {
      continue;
    }
    return false;
  }
  return true;
}

class Updater {
  constructor(renderer) {
    this._renderer = renderer;
    this._callbacks = [];
  }

  _enqueueCallback(callback, publicInstance) {
    if (typeof callback === 'function' && publicInstance) {
      this._callbacks.push({
        callback,
        publicInstance,
      });
    }
  }

  _invokeCallbacks() {
    const callbacks = this._callbacks;
    this._callbacks = [];

    callbacks.forEach(({callback, publicInstance}) => {
      callback.call(publicInstance);
    });
  }

  isMounted(publicInstance) {
    return !!this._renderer._element;
  }

  enqueueForceUpdate(publicInstance, callback, callerName) {
    this._enqueueCallback(callback, publicInstance);
    this._renderer._forcedUpdate = true;
    this._renderer.render(this._renderer._element, this._renderer._context);
  }

  enqueueReplaceState(publicInstance, completeState, callback, callerName) {
    this._enqueueCallback(callback, publicInstance);
    this._renderer._newState = completeState;
    this._renderer.render(this._renderer._element, this._renderer._context);
  }

  enqueueSetState(publicInstance, partialState, callback, callerName) {
    this._enqueueCallback(callback, publicInstance);
    const currentState = this._renderer._newState || publicInstance.state;

    if (typeof partialState === 'function') {
      partialState = partialState.call(
        publicInstance,
        currentState,
        publicInstance.props,
      );
    }

    // Null and undefined are treated as no-ops.
    if (partialState === null || partialState === undefined) {
      return;
    }

    this._renderer._newState = {
      ...currentState,
      ...partialState,
    };

    this._renderer.render(this._renderer._element, this._renderer._context);
  }
}

function createHook() {
  return {
    memoizedState: null,
    queue: null,
    next: null,
  };
}

function basicStateReducer(state, action) {
  return typeof action === 'function' ? action(state) : action;
}

class ReactShallowRenderer {
  static createRenderer = function() {
    return new ReactShallowRenderer();
  };

  constructor() {
    this._reset();
  }

  _reset() {
    this._context = null;
    this._element = null;
    this._instance = null;
    this._newState = null;
    this._rendered = null;
    this._rendering = false;
    this._forcedUpdate = false;
    this._updater = new Updater(this);
    this._dispatcher = this._createDispatcher();
    this._workInProgressHook = null;
    this._firstWorkInProgressHook = null;
    this._isReRender = false;
    this._didScheduleRenderPhaseUpdate = false;
    this._renderPhaseUpdates = null;
    this._numberOfReRenders = 0;
  }

  _validateCurrentlyRenderingComponent() {
    if (!(this._rendering && !this._instance)) {
      throw Error(`Invalid hook call. Hooks can only be called inside of the body of a function component. This could happen for one of the following reasons:
1. You might have mismatching versions of React and the renderer (such as React DOM)
2. You might be breaking the Rules of Hooks
3. You might have more than one copy of React in the same app
See https://fb.me/react-invalid-hook-call for tips about how to debug and fix this problem.`);
    }
  }

  _createDispatcher() {
    const useReducer = (reducer, initialArg, init) => {
      this._validateCurrentlyRenderingComponent();
      this._createWorkInProgressHook();
      const workInProgressHook = this._workInProgressHook;

      if (this._isReRender) {
        // This is a re-render.
        const queue = workInProgressHook.queue;
        const dispatch = queue.dispatch;
        if (this._numberOfReRenders > 0) {
          // Apply the new render phase updates to the previous current hook.
          if (this._renderPhaseUpdates !== null) {
            // Render phase updates are stored in a map of queue -> linked list
            const firstRenderPhaseUpdate = this._renderPhaseUpdates.get(queue);
            if (firstRenderPhaseUpdate !== undefined) {
              this._renderPhaseUpdates.delete(queue);
              let newState = workInProgressHook.memoizedState;
              let update = firstRenderPhaseUpdate;
              do {
                const action = update.action;
                newState = reducer(newState, action);
                update = update.next;
              } while (update !== null);
              workInProgressHook.memoizedState = newState;
              return [newState, dispatch];
            }
          }
          return [workInProgressHook.memoizedState, dispatch];
        }
        // Process updates outside of render
        let newState = workInProgressHook.memoizedState;
        let update = queue.first;
        if (update !== null) {
          do {
            const action = update.action;
            newState = reducer(newState, action);
            update = update.next;
          } while (update !== null);
          queue.first = null;
          workInProgressHook.memoizedState = newState;
        }
        return [newState, dispatch];
      } else {
        let initialState;
        if (reducer === basicStateReducer) {
          // Special case for `useState`.
          initialState =
            typeof initialArg === 'function' ? initialArg() : initialArg;
        } else {
          initialState = init !== undefined ? init(initialArg) : initialArg;
        }
        workInProgressHook.memoizedState = initialState;
        const queue = (workInProgressHook.queue = {
          first: null,
          dispatch: null,
        });
        const dispatch = (queue.dispatch = this._dispatchAction.bind(
          this,
          queue,
        ));
        return [workInProgressHook.memoizedState, dispatch];
      }
    };

    const useState = initialState => {
      return useReducer(
        basicStateReducer,
        // useReducer has a special case to support lazy useState initializers
        initialState,
      );
    };

    const useMemo = (nextCreate, deps) => {
      this._validateCurrentlyRenderingComponent();
      this._createWorkInProgressHook();

      const nextDeps = deps !== undefined ? deps : null;

      if (
        this._workInProgressHook !== null &&
        this._workInProgressHook.memoizedState !== null
      ) {
        const prevState = this._workInProgressHook.memoizedState;
        const prevDeps = prevState[1];
        if (nextDeps !== null) {
          if (areHookInputsEqual(nextDeps, prevDeps)) {
            return prevState[0];
          }
        }
      }

      const nextValue = nextCreate();
      this._workInProgressHook.memoizedState = [nextValue, nextDeps];
      return nextValue;
    };

    const useRef = initialValue => {
      this._validateCurrentlyRenderingComponent();
      this._createWorkInProgressHook();
      const previousRef = this._workInProgressHook.memoizedState;
      if (previousRef === null) {
        const ref = {current: initialValue};
        if (process.env.NODE_ENV !== 'production') {
          Object.seal(ref);
        }
        this._workInProgressHook.memoizedState = ref;
        return ref;
      } else {
        return previousRef;
      }
    };

    const readContext = (context, observedBits) => {
      return context._currentValue;
    };

    const noOp = () => {
      this._validateCurrentlyRenderingComponent();
    };

    const identity = fn => {
      return fn;
    };

    const useResponder = (responder, props) => ({
      props: props,
      responder,
    });

    // TODO: implement if we decide to keep the shallow renderer
    const useTransition = config => {
      this._validateCurrentlyRenderingComponent();
      const startTransition = callback => {
        callback();
      };
      return [startTransition, false];
    };

    // TODO: implement if we decide to keep the shallow renderer
    const useDeferredValue = (value, config) => {
      this._validateCurrentlyRenderingComponent();
      return value;
    };

    return {
      readContext,
      useCallback: identity,
      useContext: context => {
        this._validateCurrentlyRenderingComponent();
        return readContext(context);
      },
      useDebugValue: noOp,
      useEffect: noOp,
      useImperativeHandle: noOp,
      useLayoutEffect: noOp,
      useMemo,
      useReducer,
      useRef,
      useState,
      useResponder,
      useTransition,
      useDeferredValue,
    };
  }

  _dispatchAction(queue, action) {
    if (!(this._numberOfReRenders < RE_RENDER_LIMIT)) {
      throw Error(
        `Too many re-renders. React limits the number of renders to prevent an infinite loop.`,
      );
    }

    if (this._rendering) {
      // This is a render phase update. Stash it in a lazily-created map of
      // queue -> linked list of updates. After this render pass, we'll restart
      // and apply the stashed updates on top of the work-in-progress hook.
      this._didScheduleRenderPhaseUpdate = true;
      const update = {
        action,
        next: null,
      };
      let renderPhaseUpdates = this._renderPhaseUpdates;
      if (renderPhaseUpdates === null) {
        this._renderPhaseUpdates = renderPhaseUpdates = new Map();
      }
      const firstRenderPhaseUpdate = renderPhaseUpdates.get(queue);
      if (firstRenderPhaseUpdate === undefined) {
        renderPhaseUpdates.set(queue, update);
      } else {
        // Append the update to the end of the list.
        let lastRenderPhaseUpdate = firstRenderPhaseUpdate;
        while (lastRenderPhaseUpdate.next !== null) {
          lastRenderPhaseUpdate = lastRenderPhaseUpdate.next;
        }
        lastRenderPhaseUpdate.next = update;
      }
    } else {
      const update = {
        action,
        next: null,
      };

      // Append the update to the end of the list.
      let last = queue.first;
      if (last === null) {
        queue.first = update;
      } else {
        while (last.next !== null) {
          last = last.next;
        }
        last.next = update;
      }

      // Re-render now.
      this.render(this._element, this._context);
    }
  }

  _createWorkInProgressHook() {
    if (this._workInProgressHook === null) {
      // This is the first hook in the list
      if (this._firstWorkInProgressHook === null) {
        this._isReRender = false;
        this._firstWorkInProgressHook = this._workInProgressHook = createHook();
      } else {
        // There's already a work-in-progress. Reuse it.
        this._isReRender = true;
        this._workInProgressHook = this._firstWorkInProgressHook;
      }
    } else {
      if (this._workInProgressHook.next === null) {
        this._isReRender = false;
        // Append to the end of the list
        this._workInProgressHook = this._workInProgressHook.next = createHook();
      } else {
        // There's already a work-in-progress. Reuse it.
        this._isReRender = true;
        this._workInProgressHook = this._workInProgressHook.next;
      }
    }
    return this._workInProgressHook;
  }

  _finishHooks(element, context) {
    if (this._didScheduleRenderPhaseUpdate) {
      // Updates were scheduled during the render phase. They are stored in
      // the `renderPhaseUpdates` map. Call the component again, reusing the
      // work-in-progress hooks and applying the additional updates on top. Keep
      // restarting until no more updates are scheduled.
      this._didScheduleRenderPhaseUpdate = false;
      this._numberOfReRenders += 1;

      // Start over from the beginning of the list
      this._workInProgressHook = null;
      this._rendering = false;
      this.render(element, context);
    } else {
      this._workInProgressHook = null;
      this._renderPhaseUpdates = null;
      this._numberOfReRenders = 0;
    }
  }

  getMountedInstance() {
    return this._instance;
  }

  getRenderOutput() {
    return this._rendered;
  }

  render(element, context = emptyObject) {
    if (!React.isValidElement(element)) {
      throw Error(
        `ReactShallowRenderer render(): Invalid component element.${
          typeof element === 'function'
            ? ' Instead of passing a component class, make sure to instantiate ' +
              'it by passing it to React.createElement.'
            : ''
        }`,
      );
    }
    // Show a special message for host elements since it's a common case.
    if (!(typeof element.type !== 'string')) {
      throw Error(
        `ReactShallowRenderer render(): Shallow rendering works only with custom components, not primitives (${element.type}). Instead of calling \`.render(el)\` and inspecting the rendered output, look at \`el.props\` directly instead.`,
      );
    }
    if (
      !(
        isForwardRef(element) ||
        typeof element.type === 'function' ||
        isMemo(element)
      )
    ) {
      throw Error(
        `ReactShallowRenderer render(): Shallow rendering works only with custom components, but the provided element type was \`${
          Array.isArray(element.type)
            ? 'array'
            : element.type === null
            ? 'null'
            : typeof element.type
        }\`.`,
      );
    }

    if (this._rendering) {
      return;
    }
    if (this._element != null && this._element.type !== element.type) {
      this._reset();
    }

    const elementType = isMemo(element) ? element.type.type : element.type;
    const previousElement = this._element;

    this._rendering = true;
    this._element = element;
    this._context = getMaskedContext(elementType.contextTypes, context);

    // Inner memo component props aren't currently validated in createElement.
    let prevGetStack;
    if (process.env.NODE_ENV !== 'production') {
      prevGetStack = ReactDebugCurrentFrame.getCurrentStack;
      ReactDebugCurrentFrame.getCurrentStack = getStackAddendum;
    }
    try {
      if (isMemo(element) && elementType.propTypes) {
        currentlyValidatingElement = element;
        checkPropTypes(
          elementType.propTypes,
          element.props,
          'prop',
          getComponentName(elementType),
        );
      }

      if (this._instance) {
        this._updateClassComponent(elementType, element, this._context);
      } else {
        if (shouldConstruct(elementType)) {
          this._instance = new elementType(
            element.props,
            this._context,
            this._updater,
          );
          if (typeof elementType.getDerivedStateFromProps === 'function') {
            const partialState = elementType.getDerivedStateFromProps.call(
              null,
              element.props,
              this._instance.state,
            );
            if (partialState != null) {
              this._instance.state = Object.assign(
                {},
                this._instance.state,
                partialState,
              );
            }
          }

          if (elementType.contextTypes) {
            currentlyValidatingElement = element;
            checkPropTypes(
              elementType.contextTypes,
              this._context,
              'context',
              getName(elementType, this._instance),
            );

            currentlyValidatingElement = null;
          }

          this._mountClassComponent(elementType, element, this._context);
        } else {
          let shouldRender = true;
          if (isMemo(element) && previousElement !== null) {
            // This is a Memo component that is being re-rendered.
            const compare = element.type.compare || shallowEqual;
            if (compare(previousElement.props, element.props)) {
              shouldRender = false;
            }
          }
          if (shouldRender) {
            const prevDispatcher = ReactCurrentDispatcher.current;
            ReactCurrentDispatcher.current = this._dispatcher;
            try {
              // elementType could still be a ForwardRef if it was
              // nested inside Memo.
              if (elementType.$$typeof === ForwardRef) {
                if (!(typeof elementType.render === 'function')) {
                  throw Error(
                    `forwardRef requires a render function but was given ${typeof elementType.render}.`,
                  );
                }
                this._rendered = elementType.render.call(
                  undefined,
                  element.props,
                  element.ref,
                );
              } else {
                this._rendered = elementType(element.props, this._context);
              }
            } finally {
              ReactCurrentDispatcher.current = prevDispatcher;
            }
            this._finishHooks(element, context);
          }
        }
      }
    } finally {
      if (process.env.NODE_ENV !== 'production') {
        ReactDebugCurrentFrame.getCurrentStack = prevGetStack;
      }
    }

    this._rendering = false;
    this._updater._invokeCallbacks();

    return this.getRenderOutput();
  }

  unmount() {
    if (this._instance) {
      if (typeof this._instance.componentWillUnmount === 'function') {
        this._instance.componentWillUnmount();
      }
    }
    this._reset();
  }

  _mountClassComponent(elementType, element, context) {
    this._instance.context = context;
    this._instance.props = element.props;
    this._instance.state = this._instance.state || null;
    this._instance.updater = this._updater;

    if (
      typeof this._instance.UNSAFE_componentWillMount === 'function' ||
      typeof this._instance.componentWillMount === 'function'
    ) {
      const beforeState = this._newState;

      // In order to support react-lifecycles-compat polyfilled components,
      // Unsafe lifecycles should not be invoked for components using the new APIs.
      if (
        typeof elementType.getDerivedStateFromProps !== 'function' &&
        typeof this._instance.getSnapshotBeforeUpdate !== 'function'
      ) {
        if (typeof this._instance.componentWillMount === 'function') {
          this._instance.componentWillMount();
        }
        if (typeof this._instance.UNSAFE_componentWillMount === 'function') {
          this._instance.UNSAFE_componentWillMount();
        }
      }

      // setState may have been called during cWM
      if (beforeState !== this._newState) {
        this._instance.state = this._newState || emptyObject;
      }
    }

    this._rendered = this._instance.render();
    // Intentionally do not call componentDidMount()
    // because DOM refs are not available.
  }

  _updateClassComponent(elementType, element, context) {
    const {props} = element;

    const oldState = this._instance.state || emptyObject;
    const oldProps = this._instance.props;

    if (oldProps !== props) {
      // In order to support react-lifecycles-compat polyfilled components,
      // Unsafe lifecycles should not be invoked for components using the new APIs.
      if (
        typeof elementType.getDerivedStateFromProps !== 'function' &&
        typeof this._instance.getSnapshotBeforeUpdate !== 'function'
      ) {
        if (typeof this._instance.componentWillReceiveProps === 'function') {
          this._instance.componentWillReceiveProps(props, context);
        }
        if (
          typeof this._instance.UNSAFE_componentWillReceiveProps === 'function'
        ) {
          this._instance.UNSAFE_componentWillReceiveProps(props, context);
        }
      }
    }

    // Read state after cWRP in case it calls setState
    let state = this._newState || oldState;
    if (typeof elementType.getDerivedStateFromProps === 'function') {
      const partialState = elementType.getDerivedStateFromProps.call(
        null,
        props,
        state,
      );
      if (partialState != null) {
        state = Object.assign({}, state, partialState);
      }
    }

    let shouldUpdate = true;
    if (this._forcedUpdate) {
      shouldUpdate = true;
      this._forcedUpdate = false;
    } else if (typeof this._instance.shouldComponentUpdate === 'function') {
      shouldUpdate = !!this._instance.shouldComponentUpdate(
        props,
        state,
        context,
      );
    } else if (
      elementType.prototype &&
      elementType.prototype.isPureReactComponent
    ) {
      shouldUpdate =
        !shallowEqual(oldProps, props) || !shallowEqual(oldState, state);
    }

    if (shouldUpdate) {
      // In order to support react-lifecycles-compat polyfilled components,
      // Unsafe lifecycles should not be invoked for components using the new APIs.
      if (
        typeof elementType.getDerivedStateFromProps !== 'function' &&
        typeof this._instance.getSnapshotBeforeUpdate !== 'function'
      ) {
        if (typeof this._instance.componentWillUpdate === 'function') {
          this._instance.componentWillUpdate(props, state, context);
        }
        if (typeof this._instance.UNSAFE_componentWillUpdate === 'function') {
          this._instance.UNSAFE_componentWillUpdate(props, state, context);
        }
      }
    }

    this._instance.context = context;
    this._instance.props = props;
    this._instance.state = state;
    this._newState = null;

    if (shouldUpdate) {
      this._rendered = this._instance.render();
    }
    // Intentionally do not call componentDidUpdate()
    // because DOM refs are not available.
  }
}

let currentlyValidatingElement = null;

function getDisplayName(element) {
  if (element == null) {
    return '#empty';
  } else if (typeof element === 'string' || typeof element === 'number') {
    return '#text';
  } else if (typeof element.type === 'string') {
    return element.type;
  } else {
    const elementType = isMemo(element) ? element.type.type : element.type;
    return elementType.displayName || elementType.name || 'Unknown';
  }
}

function getStackAddendum() {
  let stack = '';
  if (currentlyValidatingElement) {
    const name = getDisplayName(currentlyValidatingElement);
    const owner = currentlyValidatingElement._owner;
    stack += describeComponentFrame(
      name,
      currentlyValidatingElement._source,
      owner && getComponentName(owner.type),
    );
  }
  return stack;
}

function getName(type, instance) {
  const constructor = instance && instance.constructor;
  return (
    type.displayName ||
    (constructor && constructor.displayName) ||
    type.name ||
    (constructor && constructor.name) ||
    null
  );
}

function shouldConstruct(Component) {
  return !!(Component.prototype && Component.prototype.isReactComponent);
}

function getMaskedContext(contextTypes, unmaskedContext) {
  if (!contextTypes || !unmaskedContext) {
    return emptyObject;
  }
  const context = {};
  for (let key in contextTypes) {
    context[key] = unmaskedContext[key];
  }
  return context;
}

export default ReactShallowRenderer;