instantiateReactComponent.js

/**
 * Copyright 2013-2014, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule instantiateReactComponent
 * @typechecks static-only
 */

"use strict";

var warning = require('warning');

var ReactElement = require('ReactElement');
var ReactLegacyElement = require('ReactLegacyElement');
var ReactNativeComponent = require('ReactNativeComponent');
var ReactEmptyComponent = require('ReactEmptyComponent');

/**
 * Given an `element` create an instance that will actually be mounted.
 *
 * @param {object} element
 * @param {*} parentCompositeType The composite type that resolved this.
 * @return {object} A new instance of the element's constructor.
 * @protected
 */
function instantiateReactComponent(element, parentCompositeType) {
  var instance;

  if (__DEV__) {
    warning(
      element && (typeof element.type === 'function' ||
                     typeof element.type === 'string'),
      'Only functions or strings can be mounted as React components.'
    );

    // Resolve mock instances
    if (element.type._mockedReactClassConstructor) {
      // If this is a mocked class, we treat the legacy factory as if it was the
      // class constructor for future proofing unit tests. Because this might
      // be mocked as a legacy factory, we ignore any warnings triggerd by
      // this temporary hack.
      ReactLegacyElement._isLegacyCallWarningEnabled = false;
      try {
        instance = new element.type._mockedReactClassConstructor(
          element.props
        );
      } finally {
        ReactLegacyElement._isLegacyCallWarningEnabled = true;
      }

      // If the mock implementation was a legacy factory, then it returns a
      // element. We need to turn this into a real component instance.
      if (ReactElement.isValidElement(instance)) {
        instance = new instance.type(instance.props);
      }

      var render = instance.render;
      if (!render) {
        // For auto-mocked factories, the prototype isn't shimmed and therefore
        // there is no render function on the instance. We replace the whole
        // component with an empty component instance instead.
        element = ReactEmptyComponent.getEmptyComponent();
      } else {
        if (render._isMockFunction && !render._getMockImplementation()) {
          // Auto-mocked components may have a prototype with a mocked render
          // function. For those, we'll need to mock the result of the render
          // since we consider undefined to be invalid results from render.
          render.mockImplementation(
            ReactEmptyComponent.getEmptyComponent
          );
        }
        instance.construct(element);
        return instance;
      }
    }
  }

  // Special case string values
  if (typeof element.type === 'string') {
    instance = ReactNativeComponent.createInstanceForTag(
      element.type,
      element.props,
      parentCompositeType
    );
  } else {
    // Normal case for non-mocks and non-strings
    instance = new element.type(element.props);
  }

  if (__DEV__) {
    warning(
      typeof instance.construct === 'function' &&
      typeof instance.mountComponent === 'function' &&
      typeof instance.receiveComponent === 'function',
      'Only React Components can be mounted.'
    );
  }

  // This actually sets up the internal instance. This will become decoupled
  // from the public instance in a future diff.
  instance.construct(element);

  return instance;
}

module.exports = instantiateReactComponent;