react/src/core/ReactComponent.js

/**
 * Copyright 2013 Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @providesModule ReactComponent
 */

"use strict";

var ReactComponentEnvironment = require('ReactComponentEnvironment');
var ReactCurrentOwner = require('ReactCurrentOwner');
var ReactOwner = require('ReactOwner');
var ReactUpdates = require('ReactUpdates');

var invariant = require('invariant');
var keyMirror = require('keyMirror');
var merge = require('merge');

/**
 * Every React component is in one of these life cycles.
 */
var ComponentLifeCycle = keyMirror({
  /**
   * Mounted components have a DOM node representation and are capable of
   * receiving new props.
   */
  MOUNTED: null,
  /**
   * Unmounted components are inactive and cannot receive new props.
   */
  UNMOUNTED: null
});

/**
 * Warn if there's no key explicitly set on dynamic arrays of children.
 * This allows us to keep track of children between updates.
 */

var ownerHasWarned = {};

/**
 * Warn if the component doesn't have an explicit key assigned to it.
 * This component is in an array. The array could grow and shrink or be
 * reordered. All children, that hasn't already been validated, are required to
 * have a "key" property assigned to it.
 *
 * @internal
 * @param {ReactComponent} component Component that requires a key.
 */
function validateExplicitKey(component) {
  if (component.__keyValidated__ || component.props.key != null) {
    return;
  }
  component.__keyValidated__ = true;

  // We can't provide friendly warnings for top level components.
  if (!ReactCurrentOwner.current) {
    return;
  }

  // Name of the component whose render method tried to pass children.
  var currentName = ReactCurrentOwner.current.constructor.displayName;
  if (ownerHasWarned.hasOwnProperty(currentName)) {
    return;
  }
  ownerHasWarned[currentName] = true;

  var message = 'Each child in an array should have a unique "key" prop. ' +
                'Check the render method of ' + currentName + '.';
  if (!component.isOwnedBy(ReactCurrentOwner.current)) {
    // Name of the component that originally created this child.
    var childOwnerName =
      component._owner &&
      component._owner.constructor.displayName;

    // Usually the current owner is the offender, but if it accepts
    // children as a property, it may be the creator of the child that's
    // responsible for assigning it a key.
    message += ' It was passed a child from ' + childOwnerName + '.';
  }

  console.warn(message);
}

/**
 * Ensure that every component either is passed in a static location or, if
 * if it's passed in an array, has an explicit key property defined.
 *
 * @internal
 * @param {*} component Statically passed child of any type.
 * @return {boolean}
 */
function validateChildKeys(component) {
  if (Array.isArray(component)) {
    for (var i = 0; i < component.length; i++) {
      var child = component[i];
      if (ReactComponent.isValidComponent(child)) {
        validateExplicitKey(child);
      }
    }
  } else if (ReactComponent.isValidComponent(component)) {
    // This component was passed in a valid location.
    component.__keyValidated__ = true;
  }
}

/**
 * Components are the basic units of composition in React.
 *
 * Every component accepts a set of keyed input parameters known as "props" that
 * are initialized by the constructor. Once a component is mounted, the props
 * can be mutated using `setProps` or `replaceProps`.
 *
 * Every component is capable of the following operations:
 *
 *   `mountComponent`
 *     Initializes the component, renders markup, and registers event listeners.
 *
 *   `receiveComponent`
 *     Updates the rendered DOM nodes to match the given component.
 *
 *   `unmountComponent`
 *     Releases any resources allocated by this component.
 *
 * Components can also be "owned" by other components. Being owned by another
 * component means being constructed by that component. This is different from
 * being the child of a component, which means having a DOM representation that
 * is a child of the DOM representation of that component.
 *
 * @class ReactComponent
 */
var ReactComponent = {

  /**
   * @param {?object} object
   * @return {boolean} True if `object` is a valid component.
   * @final
   */
  isValidComponent: function(object) {
    return !!(
      object &&
      typeof object.mountComponentIntoNode === 'function' &&
      typeof object.receiveComponent === 'function'
    );
  },

  /**
   * Generate a key string that identifies a component within a set.
   *
   * @param {*} component A component that could contain a manual key.
   * @param {number} index Index that is used if a manual key is not provided.
   * @return {string}
   * @internal
   */
  getKey: function(component, index) {
    if (component && component.props && component.props.key != null) {
      // Explicit key
      return '{' + component.props.key + '}';
    }
    // Implicit key determined by the index in the set
    return '[' + index + ']';
  },

  /**
   * @internal
   */
  LifeCycle: ComponentLifeCycle,

  /**
   * Injected module that provides ability to mutate individual properties.
   * Injected into the base class because many different subclasses need access
   * to this.
   *
   * @internal
   */
  DOMIDOperations: ReactComponentEnvironment.DOMIDOperations,

  /**
   * Optionally injectable environment dependent cleanup hook. (server vs.
   * browser etc). Example: A browser system caches DOM nodes based on component
   * ID and must remove that cache entry when this instance is unmounted.
   *
   * @private
   */
  unmountIDFromEnvironment: ReactComponentEnvironment.unmountIDFromEnvironment,

  /**
   * The "image" of a component tree, is the platform specific (typically
   * serialized) data that represents a tree of lower level UI building blocks.
   * On the web, this "image" is HTML markup which describes a construction of
   * low level `div` and `span` nodes. Other platforms may have different
   * encoding of this "image". This must be injected.
   *
   * @private
   */
  mountImageIntoNode: ReactComponentEnvironment.mountImageIntoNode,

  /**
   * React references `ReactReconcileTransaction` using this property in order
   * to allow dependency injection.
   *
   * @internal
   */
  ReactReconcileTransaction:
    ReactComponentEnvironment.ReactReconcileTransaction,

  /**
   * Base functionality for every ReactComponent constructor. Mixed into the
   * `ReactComponent` prototype, but exposed statically for easy access.
   *
   * @lends {ReactComponent.prototype}
   */
  Mixin: merge(ReactComponentEnvironment.Mixin, {

    /**
     * Checks whether or not this component is mounted.
     *
     * @return {boolean} True if mounted, false otherwise.
     * @final
     * @protected
     */
    isMounted: function() {
      return this._lifeCycleState === ComponentLifeCycle.MOUNTED;
    },

    /**
     * Sets a subset of the props.
     *
     * @param {object} partialProps Subset of the next props.
     * @param {?function} callback Called after props are updated.
     * @final
     * @public
     */
    setProps: function(partialProps, callback) {
      // Merge with `_pendingProps` if it exists, otherwise with existing props.
      this.replaceProps(
        merge(this._pendingProps || this.props, partialProps),
        callback
      );
    },

    /**
     * Replaces all of the props.
     *
     * @param {object} props New props.
     * @param {?function} callback Called after props are updated.
     * @final
     * @public
     */
    replaceProps: function(props, callback) {
      invariant(
        !this._owner,
        'replaceProps(...): You called `setProps` or `replaceProps` on a ' +
        'component with an owner. This is an anti-pattern since props will ' +
        'get reactively updated when rendered. Instead, change the owner\'s ' +
        '`render` method to pass the correct value as props to the component ' +
        'where it is created.'
      );
      invariant(
        this.isMounted(),
        'replaceProps(...): Can only update a mounted component.'
      );
      this._pendingProps = props;
      ReactUpdates.enqueueUpdate(this, callback);
    },

    /**
     * Base constructor for all React component.
     *
     * Subclasses that override this method should make sure to invoke
     * `ReactComponent.Mixin.construct.call(this, ...)`.
     *
     * @param {?object} initialProps
     * @param {*} children
     * @internal
     */
    construct: function(initialProps, children) {
      this.props = initialProps || {};
      // Record the component responsible for creating this component.
      this._owner = ReactCurrentOwner.current;
      // All components start unmounted.
      this._lifeCycleState = ComponentLifeCycle.UNMOUNTED;

      this._pendingProps = null;
      this._pendingCallbacks = null;

      // Unlike _pendingProps and _pendingCallbacks, we won't use null to
      // indicate that nothing is pending because it's possible for a component
      // to have a null owner. Instead, an owner change is pending when
      // this._owner !== this._pendingOwner.
      this._pendingOwner = this._owner;

      // Children can be more than one argument
      var childrenLength = arguments.length - 1;
      if (childrenLength === 1) {
        if (__DEV__) {
          validateChildKeys(children);
        }
        this.props.children = children;
      } else if (childrenLength > 1) {
        var childArray = Array(childrenLength);
        for (var i = 0; i < childrenLength; i++) {
          if (__DEV__) {
            validateChildKeys(arguments[i + 1]);
          }
          childArray[i] = arguments[i + 1];
        }
        this.props.children = childArray;
      }
    },

    /**
     * Initializes the component, renders markup, and registers event listeners.
     *
     * NOTE: This does not insert any nodes into the DOM.
     *
     * Subclasses that override this method should make sure to invoke
     * `ReactComponent.Mixin.mountComponent.call(this, ...)`.
     *
     * @param {string} rootID DOM ID of the root node.
     * @param {ReactReconcileTransaction} transaction
     * @param {number} mountDepth number of components in the owner hierarchy.
     * @return {?string} Rendered markup to be inserted into the DOM.
     * @internal
     */
    mountComponent: function(rootID, transaction, mountDepth) {
      invariant(
        !this.isMounted(),
        'mountComponent(%s, ...): Can only mount an unmounted component.',
        rootID
      );
      var props = this.props;
      if (props.ref != null) {
        ReactOwner.addComponentAsRefTo(this, props.ref, this._owner);
      }
      this._rootNodeID = rootID;
      this._lifeCycleState = ComponentLifeCycle.MOUNTED;
      this._mountDepth = mountDepth;
      // Effectively: return '';
    },

    /**
     * Releases any resources allocated by `mountComponent`.
     *
     * NOTE: This does not remove any nodes from the DOM.
     *
     * Subclasses that override this method should make sure to invoke
     * `ReactComponent.Mixin.unmountComponent.call(this)`.
     *
     * @internal
     */
    unmountComponent: function() {
      invariant(
        this.isMounted(),
        'unmountComponent(): Can only unmount a mounted component.'
      );
      var props = this.props;
      if (props.ref != null) {
        ReactOwner.removeComponentAsRefFrom(this, props.ref, this._owner);
      }
      ReactComponent.unmountIDFromEnvironment(this._rootNodeID);
      this._rootNodeID = null;
      this._lifeCycleState = ComponentLifeCycle.UNMOUNTED;
    },

    /**
     * Given a new instance of this component, updates the rendered DOM nodes
     * as if that instance was rendered instead.
     *
     * Subclasses that override this method should make sure to invoke
     * `ReactComponent.Mixin.receiveComponent.call(this, ...)`.
     *
     * @param {object} nextComponent Next set of properties.
     * @param {ReactReconcileTransaction} transaction
     * @internal
     */
    receiveComponent: function(nextComponent, transaction) {
      invariant(
        this.isMounted(),
        'receiveComponent(...): Can only update a mounted component.'
      );
      this._pendingOwner = nextComponent._owner;
      this._pendingProps = nextComponent.props;
      this._performUpdateIfNecessary(transaction);
    },

    /**
     * Call `_performUpdateIfNecessary` within a new transaction.
     *
     * @param {ReactReconcileTransaction} transaction
     * @internal
     */
    performUpdateIfNecessary: function() {
      var transaction = ReactComponent.ReactReconcileTransaction.getPooled();
      transaction.perform(this._performUpdateIfNecessary, this, transaction);
      ReactComponent.ReactReconcileTransaction.release(transaction);
    },

    /**
     * If `_pendingProps` is set, update the component.
     *
     * @param {ReactReconcileTransaction} transaction
     * @internal
     */
    _performUpdateIfNecessary: function(transaction) {
      if (this._pendingProps == null) {
        return;
      }
      var prevProps = this.props;
      var prevOwner = this._owner;
      this.props = this._pendingProps;
      this._owner = this._pendingOwner;
      this._pendingProps = null;
      this.updateComponent(transaction, prevProps, prevOwner);
    },

    /**
     * Updates the component's currently mounted representation.
     *
     * @param {ReactReconcileTransaction} transaction
     * @param {object} prevProps
     * @internal
     */
    updateComponent: function(transaction, prevProps, prevOwner) {
      var props = this.props;
      // If either the owner or a `ref` has changed, make sure the newest owner
      // has stored a reference to `this`, and the previous owner (if different)
      // has forgotten the reference to `this`.
      if (this._owner !== prevOwner || props.ref !== prevProps.ref) {
        if (prevProps.ref != null) {
          ReactOwner.removeComponentAsRefFrom(
            this, prevProps.ref, prevOwner
          );
        }
        // Correct, even if the owner is the same, and only the ref has changed.
        if (props.ref != null) {
          ReactOwner.addComponentAsRefTo(this, props.ref, this._owner);
        }
      }
    },

    /**
     * Mounts this component and inserts it into the DOM.
     *
     * @param {string} rootID DOM ID of the root node.
     * @param {DOMElement} container DOM element to mount into.
     * @param {boolean} shouldReuseMarkup If true, do not insert markup
     * @final
     * @internal
     * @see {ReactMount.renderComponent}
     */
    mountComponentIntoNode: function(rootID, container, shouldReuseMarkup) {
      var transaction = ReactComponent.ReactReconcileTransaction.getPooled();
      transaction.perform(
        this._mountComponentIntoNode,
        this,
        rootID,
        container,
        transaction,
        shouldReuseMarkup
      );
      ReactComponent.ReactReconcileTransaction.release(transaction);
    },

    /**
     * @param {string} rootID DOM ID of the root node.
     * @param {DOMElement} container DOM element to mount into.
     * @param {ReactReconcileTransaction} transaction
     * @param {boolean} shouldReuseMarkup If true, do not insert markup
     * @final
     * @private
     */
    _mountComponentIntoNode: function(
        rootID,
        container,
        transaction,
        shouldReuseMarkup) {
      var markup = this.mountComponent(rootID, transaction, 0);
      ReactComponent.mountImageIntoNode(markup, container, shouldReuseMarkup);
    },

    /**
     * Checks if this component is owned by the supplied `owner` component.
     *
     * @param {ReactComponent} owner Component to check.
     * @return {boolean} True if `owners` owns this component.
     * @final
     * @internal
     */
    isOwnedBy: function(owner) {
      return this._owner === owner;
    },

    /**
     * Gets another component, that shares the same owner as this one, by ref.
     *
     * @param {string} ref of a sibling Component.
     * @return {?ReactComponent} the actual sibling Component.
     * @final
     * @internal
     */
    getSiblingByRef: function(ref) {
      var owner = this._owner;
      if (!owner || !owner.refs) {
        return null;
      }
      return owner.refs[ref];
    }
  })
};

module.exports = ReactComponent;