1 files changed, 67 insertions, 0 deletions
diff --git a/dom/base/SelectionChangeEventDispatcher.h b/dom/base/SelectionChangeEventDispatcher.h
new file mode 100644
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+++ b/dom/base/SelectionChangeEventDispatcher.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_SelectionChangeEventDispatcher_h
+#define mozilla_SelectionChangeEventDispatcher_h
+
+#include "mozilla/Attributes.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsTArray.h"
+#include "nsCOMPtr.h"
+
+class nsINode;
+class nsRange;
+
+namespace mozilla {
+
+namespace dom {
+class Document;
+class Selection;
+}  // namespace dom
+
+class SelectionChangeEventDispatcher final {
+ public:
+  // SelectionChangeEventDispatcher has to participate in cycle collection
+  // because it holds strong references to nsINodes in its mOldRanges array.
+  NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(
+      SelectionChangeEventDispatcher)
+  NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(SelectionChangeEventDispatcher)
+
+  MOZ_CAN_RUN_SCRIPT
+  void OnSelectionChange(dom::Document* aDocument, dom::Selection* aSelection,
+                         int16_t aReason);
+
+  // This field is used to keep track of the ranges which were present in the
+  // selection when the selectionchange event was previously fired. This allows
+  // for the selectionchange event to only be fired when a selection is actually
+  // changed.
+  struct RawRangeData {
+    // These properties are not void*s to avoid the potential situation where
+    // the nsINode is freed, and a new nsINode is allocated with the same
+    // address, which could potentially break the comparison logic. In reality,
+    // this is extremely unlikely to occur (potentially impossible), but these
+    // nsCOMPtrs are safer. They are never dereferenced.
+    nsCOMPtr<nsINode> mStartContainer;
+    nsCOMPtr<nsINode> mEndContainer;
+
+    // XXX These are int32_ts on nsRange, but uint32_ts in the return value
+    // of GetStart_, so I use uint32_ts here. See bug 1194256.
+    uint32_t mStartOffset;
+    uint32_t mEndOffset;
+
+    explicit RawRangeData(const nsRange* aRange);
+    bool Equals(const nsRange* aRange);
+  };
+
+ private:
+  nsTArray<RawRangeData> mOldRanges;
+
+  ~SelectionChangeEventDispatcher() = default;
+};
+
+}  // namespace mozilla
+
+#endif  // mozilla_SelectionChangeEventDispatcher_h