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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_SelectionChangeListener_h_
       7             : #define mozilla_SelectionChangeListener_h_
       8             : 
       9             : #include "nsISelectionListener.h"
      10             : #include "nsISelectionPrivate.h"
      11             : #include "mozilla/Attributes.h"
      12             : 
      13             : namespace mozilla {
      14             : namespace dom {
      15             : 
      16          32 : class SelectionChangeListener final : public nsISelectionListener
      17             : {
      18             : public:
      19             :   // SelectionChangeListener has to participate in cycle collection because
      20             :   // it holds strong references to nsINodes in its mOldRanges array.
      21             :   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
      22         238 :   NS_DECL_CYCLE_COLLECTION_CLASS(SelectionChangeListener)
      23             :   NS_DECL_NSISELECTIONLISTENER
      24             : 
      25             :   // This field is used to keep track of the ranges which were present in the
      26             :   // selection when the selectionchange event was previously fired. This allows
      27             :   // for the selectionchange event to only be fired when a selection is actually
      28             :   // changed.
      29          41 :   struct RawRangeData
      30             :   {
      31             :     // These properties are not void*s to avoid the potential situation where the
      32             :     // nsINode is freed, and a new nsINode is allocated with the same address, which
      33             :     // could potentially break the comparison logic. In reality, this is extremely
      34             :     // unlikely to occur (potentially impossible), but these nsCOMPtrs are safer.
      35             :     // They are never dereferenced.
      36             :     nsCOMPtr<nsINode> mStartContainer;
      37             :     nsCOMPtr<nsINode> mEndContainer;
      38             : 
      39             :     // XXX These are int32_ts on nsRange, but uint32_ts in the return value
      40             :     // of GetStart_, so I use uint32_ts here. See bug 1194256.
      41             :     uint32_t mStartOffset;
      42             :     uint32_t mEndOffset;
      43             : 
      44             :     explicit RawRangeData(const nsRange* aRange);
      45             :     bool Equals(const nsRange* aRange);
      46             :   };
      47             : 
      48             : private:
      49             :   nsTArray<RawRangeData> mOldRanges;
      50             : 
      51           0 :   ~SelectionChangeListener() {}
      52             : };
      53             : 
      54             : } // namespace dom
      55             : } // namespace mozilla
      56             : 
      57             : #endif // mozilla_SelectionChangeListener_h_