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       1             : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* This Source Code Form is subject to the terms of the Mozilla Public
       3             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       4             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       5             : 
       6             : #ifndef mozilla_a11y_EventQueue_h_
       7             : #define mozilla_a11y_EventQueue_h_
       8             : 
       9             : #include "AccEvent.h"
      10             : 
      11             : namespace mozilla {
      12             : namespace a11y {
      13             : 
      14             : class DocAccessible;
      15             : 
      16             : /**
      17             :  * Used to organize and coalesce pending events.
      18             :  */
      19           0 : class EventQueue
      20             : {
      21             : protected:
      22           0 :   explicit EventQueue(DocAccessible* aDocument) : mDocument(aDocument) { }
      23             : 
      24             :   /**
      25             :    * Put an accessible event into the queue to process it later.
      26             :    */
      27             :   bool PushEvent(AccEvent* aEvent);
      28             : 
      29             :   /**
      30             :    * Puts a name change event into the queue, if needed.
      31             :    */
      32             :   bool PushNameChange(Accessible* aTarget);
      33             : 
      34             :   /**
      35             :    * Process events from the queue and fires events.
      36             :    */
      37             :   void ProcessEventQueue();
      38             : 
      39             : private:
      40             :   EventQueue(const EventQueue&) = delete;
      41             :   EventQueue& operator = (const EventQueue&) = delete;
      42             : 
      43             :   // Event queue processing
      44             :   /**
      45             :    * Coalesce redundant events from the queue.
      46             :    */
      47             :   void CoalesceEvents();
      48             : 
      49             :   /**
      50             :    * Coalesce events from the same subtree.
      51             :    */
      52             :   void CoalesceReorderEvents(AccEvent* aTailEvent);
      53             : 
      54             :   /**
      55             :    * Coalesce two selection change events within the same select control.
      56             :    */
      57             :   void CoalesceSelChangeEvents(AccSelChangeEvent* aTailEvent,
      58             :                                AccSelChangeEvent* aThisEvent,
      59             :                                uint32_t aThisIndex);
      60             : 
      61             : protected:
      62             :   /**
      63             :    * The document accessible reference owning this queue.
      64             :    */
      65             :   DocAccessible* mDocument;
      66             : 
      67             :   /**
      68             :    * Pending events array. Don't make this an AutoTArray; we use
      69             :    * SwapElements() on it.
      70             :    */
      71             :   nsTArray<RefPtr<AccEvent>> mEvents;
      72             : };
      73             : 
      74             : } // namespace a11y
      75             : } // namespace mozilla
      76             : 
      77             : #endif // mozilla_a11y_EventQueue_h_