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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_TextUpdater_h__
       7             : #define mozilla_a11y_TextUpdater_h__
       8             : 
       9             : #include "AccEvent.h"
      10             : #include "HyperTextAccessible.h"
      11             : 
      12             : namespace mozilla {
      13             : namespace a11y {
      14             : 
      15             : /**
      16             :  * Used to find a difference between old and new text and fire text change
      17             :  * events.
      18             :  */
      19             : class TextUpdater
      20             : {
      21             : public:
      22             :   /**
      23             :    * Start text of the text leaf update.
      24             :    */
      25             :   static void Run(DocAccessible* aDocument, TextLeafAccessible* aTextLeaf,
      26             :                   const nsAString& aNewText);
      27             : 
      28             : private:
      29           0 :   TextUpdater(DocAccessible* aDocument, TextLeafAccessible* aTextLeaf) :
      30             :     mDocument(aDocument), mTextLeaf(aTextLeaf), mHyperText(nullptr),
      31           0 :     mTextOffset(-1) { }
      32             : 
      33           0 :   ~TextUpdater()
      34           0 :     { mDocument = nullptr; mTextLeaf = nullptr; mHyperText = nullptr; }
      35             : 
      36             :   /**
      37             :    * Update text of the text leaf accessible, fire text change and value change
      38             :    * (if applicable) events for its container hypertext accessible.
      39             :    */
      40             :   void DoUpdate(const nsAString& aNewText, const nsAString& aOldText,
      41             :                 uint32_t aSkipStart);
      42             : 
      43             : private:
      44             :   TextUpdater();
      45             :   TextUpdater(const TextUpdater&);
      46             :   TextUpdater& operator=(const TextUpdater&);
      47             : 
      48             :   /**
      49             :    * Fire text change events based on difference between strings.
      50             :    */
      51             :   void ComputeTextChangeEvents(const nsAString& aStr1,
      52             :                                const nsAString& aStr2,
      53             :                                uint32_t* aEntries,
      54             :                                nsTArray<RefPtr<AccEvent> >& aEvents);
      55             : 
      56             :   /**
      57             :    * Helper to create text change events for inserted text.
      58             :    */
      59           0 :   inline void FireInsertEvent(const nsAString& aText, uint32_t aAddlOffset,
      60             :                               nsTArray<RefPtr<AccEvent> >& aEvents)
      61             :   {
      62             :     RefPtr<AccEvent> event =
      63           0 :       new AccTextChangeEvent(mHyperText, mTextOffset + aAddlOffset,
      64           0 :                              aText, true);
      65           0 :     aEvents.AppendElement(event);
      66           0 :   }
      67             : 
      68             :   /**
      69             :    * Helper to create text change events for removed text.
      70             :    */
      71           0 :   inline void FireDeleteEvent(const nsAString& aText, uint32_t aAddlOffset,
      72             :                               nsTArray<RefPtr<AccEvent> >& aEvents)
      73             :   {
      74             :     RefPtr<AccEvent> event =
      75           0 :       new AccTextChangeEvent(mHyperText, mTextOffset + aAddlOffset,
      76           0 :                              aText, false);
      77           0 :     aEvents.AppendElement(event);
      78           0 :   }
      79             : 
      80             :   /**
      81             :    * The constant used to skip string difference calculation in case of long
      82             :    * strings.
      83             :    */
      84             :   const static uint32_t kMaxStrLen = 1 << 6;
      85             : 
      86             : private:
      87             :   DocAccessible* mDocument;
      88             :   TextLeafAccessible* mTextLeaf;
      89             :   HyperTextAccessible* mHyperText;
      90             :   int32_t mTextOffset;
      91             : };
      92             : 
      93             : } // namespace a11y
      94             : } // namespace mozilla
      95             : 
      96             : #endif