Bug 960866 part.6 mozilla::TextComposition should holds a weak reference to composition handling editor during composition r=ehsan+smaug

dom/events/TextComposition.cpp

@@ -9,6 +9,7 @@
 #include "nsContentUtils.h"
 #include "nsEventDispatcher.h"
 #include "nsIContent.h"
+#include "nsIEditor.h"
 #include "nsIMEStateManager.h"
 #include "nsIPresShell.h"
 #include "nsPresContext.h"
@@ -50,7 +51,19 @@ TextComposition::DispatchEvent(WidgetGUIEvent* aEvent,
   nsEventDispatcher::Dispatch(mNode, mPresContext,
                               aEvent, nullptr, aStatus, aCallBack);
 
-  MOZ_ASSERT_IF(aEvent->message == NS_COMPOSITION_END, !mIsComposing);
+  // Emulate editor behavior of text event handler if no editor handles
+  // composition/text events.
+  if (aEvent->message == NS_TEXT_TEXT && !HasEditor()) {
+    EditorWillHandleTextEvent(aEvent->AsTextEvent());
+    EditorDidHandleTextEvent();
+  }
+
+#ifdef DEBUG
+  else if (aEvent->message == NS_COMPOSITION_END) {
+    MOZ_ASSERT(!mIsComposing, "Why is the editor still composing?");
+    MOZ_ASSERT(!HasEditor(), "Why does the editor still keep to hold this?");
+  }
+#endif // #ifdef DEBUG
 
   // Notify composition update to widget if possible
   NotityUpdateComposition(aEvent);
@@ -142,6 +155,37 @@ TextComposition::EditorDidHandleTextEvent()
   mString = mLastData;
 }
 
+void
+TextComposition::StartHandlingComposition(nsIEditor* aEditor)
+{
+  MOZ_ASSERT(!HasEditor(), "There is a handling editor already");
+  mEditorWeak = do_GetWeakReference(aEditor);
+}
+
+void
+TextComposition::EndHandlingComposition(nsIEditor* aEditor)
+{
+#ifdef DEBUG
+  nsCOMPtr<nsIEditor> editor = GetEditor();
+  MOZ_ASSERT(editor == aEditor, "Another editor handled the composition?");
+#endif // #ifdef DEBUG
+  mEditorWeak = nullptr;
+}
+
+already_AddRefed<nsIEditor>
+TextComposition::GetEditor() const
+{
+  nsCOMPtr<nsIEditor> editor = do_QueryReferent(mEditorWeak);
+  return editor.forget();
+}
+
+bool
+TextComposition::HasEditor() const
+{
+  nsCOMPtr<nsIEditor> editor = GetEditor();
+  return !!editor;
+}
+
 /******************************************************************************
  * TextComposition::CompositionEventDispatcher
  ******************************************************************************/

dom/events/TextComposition.h

@@ -9,6 +9,7 @@
 
 #include "nsCOMPtr.h"
 #include "nsINode.h"
+#include "nsIWeakReference.h"
 #include "nsIWidget.h"
 #include "nsTArray.h"
 #include "nsThreadUtils.h"
@@ -17,8 +18,8 @@
 #include "mozilla/EventForwards.h"
 
 class nsDispatchingCallback;
+class nsIEditor;
 class nsIMEStateManager;
-class nsIWidget;
 
 namespace mozilla {
 
@@ -98,6 +99,13 @@ public:
    */
   void EditorDidHandleTextEvent();
 
+  /**
+   * StartHandlingComposition() and EndHandlingComposition() are called by
+   * editor when it holds a TextComposition instance and release it.
+   */
+  void StartHandlingComposition(nsIEditor* aEditor);
+  void EndHandlingComposition(nsIEditor* aEditor);
+
 private:
   // This class holds nsPresContext weak.  This instance shouldn't block
   // destroying it.  When the presContext is being destroyed, it's notified to
@@ -110,6 +118,9 @@ private:
   // composition.  Don't access the instance, it may not be available.
   void* mNativeContext;
 
+  // mEditorWeak is a weak reference to the focused editor handling composition.
+  nsWeakPtr mEditorWeak;
+
   // mLastData stores the data attribute of the latest composition event (except
   // the compositionstart event).
   nsString mLastData;
@@ -134,6 +145,16 @@ private:
   TextComposition() {}
   TextComposition(const TextComposition& aOther);
 
+  /**
+   * GetEditor() returns nsIEditor pointer of mEditorWeak.
+   */
+  already_AddRefed<nsIEditor> GetEditor() const;
+
+  /**
+   * HasEditor() returns true if mEditorWeak holds nsIEditor instance which is
+   * alive.  Otherwise, false.
+   */
+  bool HasEditor() const;
 
   /**
    * DispatchEvent() dispatches the aEvent to the mContent synchronously.

editor/libeditor/base/nsEditor.cpp

@@ -357,6 +357,10 @@ nsEditor::RemoveEventListeners()
     return;
   }
   reinterpret_cast<nsEditorEventListener*>(mEventListener.get())->Disconnect();
+  if (mComposition) {
+    mComposition->EndHandlingComposition(this);
+    mComposition = nullptr;
+  }
   mEventTarget = nullptr;
 }
 
@@ -2020,6 +2024,7 @@ nsEditor::EnsureComposition(mozilla::WidgetGUIEvent* aEvent)
   if (!mComposition) {
     MOZ_CRASH("nsIMEStateManager doesn't return proper composition");
   }
+  mComposition->StartHandlingComposition(this);
 }
 
 nsresult
@@ -2053,6 +2058,7 @@ nsEditor::EndIMEComposition()
   /* reset the data we need to construct a transaction */
   mIMETextNode = nullptr;
   mIMETextOffset = 0;
+  mComposition->EndHandlingComposition(this);
   mComposition = nullptr;
 
   // notify editor observers of action