react-native/Libraries/Renderer/src/renderers/native/ReactNativeReconcileTransaction.js

A framework for building native apps using React

/**
 * Copyright (c) 2015-present, 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 ReactNativeReconcileTransaction
 * @flow
 */
'use strict';

var CallbackQueue = require('CallbackQueue');
var PooledClass = require('PooledClass');
var Transaction = require('Transaction');
var ReactInstrumentation = require('ReactInstrumentation');
var ReactUpdateQueue = require('ReactUpdateQueue');

/**
 * Provides a `CallbackQueue` queue for collecting `onDOMReady` callbacks during
 * the performing of the transaction.
 */
var ON_DOM_READY_QUEUEING = {
  /**
   * Initializes the internal `onDOMReady` queue.
   */
  initialize: function() {
    this.reactMountReady.reset();
  },

  /**
   * After DOM is flushed, invoke all registered `onDOMReady` callbacks.
   */
  close: function() {
    this.reactMountReady.notifyAll();
  },
};

/**
 * Executed within the scope of the `Transaction` instance. Consider these as
 * being member methods, but with an implied ordering while being isolated from
 * each other.
 */
var TRANSACTION_WRAPPERS = [ON_DOM_READY_QUEUEING];

if (__DEV__) {
  TRANSACTION_WRAPPERS.push({
    initialize: ReactInstrumentation.debugTool.onBeginFlush,
    close: ReactInstrumentation.debugTool.onEndFlush,
  });
}

/**
 * Currently:
 * - The order that these are listed in the transaction is critical:
 * - Suppresses events.
 * - Restores selection range.
 *
 * Future:
 * - Restore document/overflow scroll positions that were unintentionally
 *   modified via DOM insertions above the top viewport boundary.
 * - Implement/integrate with customized constraint based layout system and keep
 *   track of which dimensions must be remeasured.
 *
 * @class ReactNativeReconcileTransaction
 */
function ReactNativeReconcileTransaction() {
  this.reinitializeTransaction();
  this.reactMountReady = CallbackQueue.getPooled(null);
}

var Mixin = {
  /**
   * @see Transaction
   * @abstract
   * @final
   * @return {array<object>} List of operation wrap procedures.
   *   TODO: convert to array<TransactionWrapper>
   */
  getTransactionWrappers: function() {
    return TRANSACTION_WRAPPERS;
  },

  /**
   * @return {object} The queue to collect `onDOMReady` callbacks with.
   *   TODO: convert to ReactMountReady
   */
  getReactMountReady: function() {
    return this.reactMountReady;
  },

  /**
   * @return {object} The queue to collect React async events.
   */
  getUpdateQueue: function() {
    return ReactUpdateQueue;
  },

  /**
   * Save current transaction state -- if the return value from this method is
   * passed to `rollback`, the transaction will be reset to that state.
   */
  checkpoint: function() {
    // reactMountReady is the our only stateful wrapper
    return this.reactMountReady.checkpoint();
  },

  rollback: function(checkpoint) {
    this.reactMountReady.rollback(checkpoint);
  },

  /**
   * `PooledClass` looks for this, and will invoke this before allowing this
   * instance to be reused.
   */
  destructor: function() {
    CallbackQueue.release(this.reactMountReady);
    this.reactMountReady = null;
  },
};

Object.assign(
  ReactNativeReconcileTransaction.prototype,
  Transaction,
  ReactNativeReconcileTransaction,
  Mixin
);

PooledClass.addPoolingTo(ReactNativeReconcileTransaction);

module.exports = ReactNativeReconcileTransaction;