Bug 1372829 - part1: Make mozilla::PlaceholderTransaction inherit mozilla::SupportsWeakPtr instead of nsSupportsWeakReference r=m_kato

EditorBase stores PlaceholderTransaction with nsWeakPtr.  However, retrieving its pointer requires a QI.  So, for reducing the QI cost, EditorBase should use WeakPtr instead and PlaceholderTransaction needs to inherit SupportsWeakPtr instead of nsSupportsWeakReference.

MozReview-Commit-ID: IYwSTbJebMk

--HG--
extra : rebase_source : fa728b09afa826506befbeb46aba54075ecf4787

editor/libeditor/EditorBase.cpp

@@ -126,12 +126,12 @@ using namespace widget;
  *****************************************************************************/
 
 EditorBase::EditorBase()
-  : mPlaceHolderName(nullptr)
+  : mPlaceholderName(nullptr)
   , mSelState(nullptr)
   , mModCount(0)
   , mFlags(0)
   , mUpdateCount(0)
-  , mPlaceHolderBatch(0)
+  , mPlaceholderBatch(0)
   , mAction(EditAction::none)
   , mIMETextOffset(0)
   , mIMETextLength(0)
@@ -680,29 +680,29 @@ EditorBase::GetSelection(SelectionType aSelectionType)
 NS_IMETHODIMP
 EditorBase::DoTransaction(nsITransaction* aTxn)
 {
-  if (mPlaceHolderBatch && !mPlaceHolderTxn) {
-    nsCOMPtr<nsIAbsorbingTransaction> placeholderTransaction =
-      new PlaceholderTransaction(*this, mPlaceHolderName, Move(mSelState));
+  if (mPlaceholderBatch && !mPlaceholderTransactionWeak) {
+    RefPtr<PlaceholderTransaction> placeholderTransaction =
+      new PlaceholderTransaction(*this, mPlaceholderName, Move(mSelState));
 
     // Save off weak reference to placeholder transaction
-    mPlaceHolderTxn = do_GetWeakReference(placeholderTransaction);
+    mPlaceholderTransactionWeak = placeholderTransaction;
 
-    // QI to an nsITransaction since that's what DoTransaction() expects
-    nsCOMPtr<nsITransaction> transaction =
-      do_QueryInterface(placeholderTransaction);
     // We will recurse, but will not hit this case in the nested call
-    DoTransaction(transaction);
+    DoTransaction(placeholderTransaction);
 
     if (mTxnMgr) {
-      nsCOMPtr<nsITransaction> topTxn = mTxnMgr->PeekUndoStack();
-      if (topTxn) {
-        placeholderTransaction = do_QueryInterface(topTxn);
-        if (placeholderTransaction) {
+      nsCOMPtr<nsITransaction> topTransaction = mTxnMgr->PeekUndoStack();
+      nsCOMPtr<nsIAbsorbingTransaction> topAbsorbingTransaction =
+        do_QueryInterface(topTransaction);
+      if (topAbsorbingTransaction) {
+        RefPtr<PlaceholderTransaction> topPlaceholderTransaction =
+          topAbsorbingTransaction->AsPlaceholderTransaction();
+        if (topPlaceholderTransaction) {
           // there is a placeholder transaction on top of the undo stack.  It
           // is either the one we just created, or an earlier one that we are
           // now merging into.  From here on out remember this placeholder
           // instead of the one we just created.
-          mPlaceHolderTxn = do_GetWeakReference(placeholderTransaction);
+          mPlaceholderTransactionWeak = topPlaceholderTransaction;
         }
       }
     }
@@ -916,13 +916,13 @@ EditorBase::EndTransaction()
 NS_IMETHODIMP
 EditorBase::BeginPlaceHolderTransaction(nsIAtom* aName)
 {
-  NS_PRECONDITION(mPlaceHolderBatch >= 0, "negative placeholder batch count!");
-  if (!mPlaceHolderBatch) {
+  MOZ_ASSERT(mPlaceholderBatch >= 0, "negative placeholder batch count!");
+  if (!mPlaceholderBatch) {
     NotifyEditorObservers(eNotifyEditorObserversOfBefore);
     // time to turn on the batch
     BeginUpdateViewBatch();
-    mPlaceHolderTxn = nullptr;
-    mPlaceHolderName = aName;
+    mPlaceholderTransactionWeak = nullptr;
+    mPlaceholderName = aName;
     RefPtr<Selection> selection = GetSelection();
     if (selection) {
       mSelState = MakeUnique<SelectionState>();
@@ -932,12 +932,12 @@ EditorBase::BeginPlaceHolderTransaction(nsIAtom* aName)
       // So if current selection is into IME text node, it might be failed
       // to restore selection by UndoTransaction.
       // So we need update selection by range updater.
-      if (mPlaceHolderName == nsGkAtoms::IMETxnName) {
+      if (mPlaceholderName == nsGkAtoms::IMETxnName) {
         mRangeUpdater.RegisterSelectionState(*mSelState);
       }
     }
   }
-  mPlaceHolderBatch++;
+  mPlaceholderBatch++;
 
   return NS_OK;
 }
@@ -945,8 +945,9 @@ EditorBase::BeginPlaceHolderTransaction(nsIAtom* aName)
 NS_IMETHODIMP
 EditorBase::EndPlaceHolderTransaction()
 {
-  NS_PRECONDITION(mPlaceHolderBatch > 0, "zero or negative placeholder batch count when ending batch!");
-  if (mPlaceHolderBatch == 1) {
+  MOZ_ASSERT(mPlaceholderBatch > 0,
+             "zero or negative placeholder batch count when ending batch!");
+  if (mPlaceholderBatch == 1) {
     RefPtr<Selection> selection = GetSelection();
 
     // By making the assumption that no reflow happens during the calls
@@ -986,21 +987,16 @@ EditorBase::EndPlaceHolderTransaction()
     if (mSelState) {
       // we saved the selection state, but never got to hand it to placeholder
       // (else we ould have nulled out this pointer), so destroy it to prevent leaks.
-      if (mPlaceHolderName == nsGkAtoms::IMETxnName) {
+      if (mPlaceholderName == nsGkAtoms::IMETxnName) {
         mRangeUpdater.DropSelectionState(*mSelState);
       }
       mSelState = nullptr;
     }
     // We might have never made a placeholder if no action took place.
-    if (mPlaceHolderTxn) {
-      nsCOMPtr<nsIAbsorbingTransaction> plcTxn = do_QueryReferent(mPlaceHolderTxn);
-      if (plcTxn) {
-        plcTxn->EndPlaceHolderBatch();
-      } else {
-        // in the future we will check to make sure undo is off here,
-        // since that is the only known case where the placeholdertxn would disappear on us.
-        // For now just removing the assert.
-      }
+    if (mPlaceholderTransactionWeak) {
+      RefPtr<PlaceholderTransaction> placeholderTransaction =
+        mPlaceholderTransactionWeak.get();
+      placeholderTransaction->EndPlaceHolderBatch();
       // notify editor observers of action but if composing, it's done by
       // compositionchange event handler.
       if (!mComposition) {
@@ -1010,7 +1006,7 @@ EditorBase::EndPlaceHolderTransaction()
       NotifyEditorObservers(eNotifyEditorObserversOfCancel);
     }
   }
-  mPlaceHolderBatch--;
+  mPlaceholderBatch--;
 
   return NS_OK;
 }

editor/libeditor/EditorBase.h

@@ -9,8 +9,9 @@
 #include "mozilla/Assertions.h"         // for MOZ_ASSERT, etc.
 #include "mozilla/OwningNonNull.h"      // for OwningNonNull
 #include "mozilla/SelectionState.h"     // for RangeUpdater, etc.
-#include "mozilla/StyleSheet.h"   // for StyleSheet
+#include "mozilla/StyleSheet.h"         // for StyleSheet
 #include "mozilla/UniquePtr.h"
+#include "mozilla/WeakPtr.h"            // for WeakPtr
 #include "mozilla/dom/Text.h"
 #include "nsCOMPtr.h"                   // for already_AddRefed, nsCOMPtr
 #include "nsCycleCollectionParticipant.h"
@@ -116,6 +117,7 @@ class HTMLEditor;
 class InsertNodeTransaction;
 class InsertTextTransaction;
 class JoinNodeTransaction;
+class PlaceholderTransaction;
 class RemoveStyleSheetTransaction;
 class SetTextTransaction;
 class SplitNodeTransaction;
@@ -1008,11 +1010,11 @@ protected:
   // Weak reference to the nsISelectionController.
   nsWeakPtr mSelConWeak;
   // Weak reference to placeholder for begin/end batch purposes.
-  nsWeakPtr mPlaceHolderTxn;
+  WeakPtr<PlaceholderTransaction> mPlaceholderTransactionWeak;
   // Weak reference to the nsIDOMDocument.
   nsWeakPtr mDocWeak;
   // Name of placeholder transaction.
-  nsIAtom* mPlaceHolderName;
+  nsIAtom* mPlaceholderName;
   // Saved selection state for placeholder transaction batching.
   mozilla::UniquePtr<SelectionState> mSelState;
   // IME composition this is not null between compositionstart and
@@ -1045,7 +1047,7 @@ protected:
   int32_t mUpdateCount;
 
   // Nesting count for batching.
-  int32_t mPlaceHolderBatch;
+  int32_t mPlaceholderBatch;
   // The current editor action.
   EditAction mAction;
 

editor/libeditor/PlaceholderTransaction.cpp

@@ -56,7 +56,6 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(PlaceholderTransaction)
   NS_INTERFACE_MAP_ENTRY(nsIAbsorbingTransaction)
-  NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
 NS_INTERFACE_MAP_END_INHERITING(EditAggregateTransaction)
 
 NS_IMPL_ADDREF_INHERITED(PlaceholderTransaction, EditAggregateTransaction)

editor/libeditor/PlaceholderTransaction.h

@@ -9,6 +9,7 @@
 #include "EditAggregateTransaction.h"
 #include "mozilla/EditorUtils.h"
 #include "mozilla/UniquePtr.h"
+#include "mozilla/WeakPtr.h"
 #include "nsIAbsorbingTransaction.h"
 #include "nsIDOMNode.h"
 #include "nsCOMPtr.h"
@@ -26,11 +27,14 @@ class CompositionTransaction;
  * transactions it has absorbed.
  */
 
-class PlaceholderTransaction final : public EditAggregateTransaction,
-                                     public nsIAbsorbingTransaction,
-                                     public nsSupportsWeakReference
+class PlaceholderTransaction final
+ : public EditAggregateTransaction
+ , public nsIAbsorbingTransaction
+ , public SupportsWeakPtr<PlaceholderTransaction>
 {
 public:
+  MOZ_DECLARE_WEAKREFERENCE_TYPENAME(PlaceholderTransaction)
+
   NS_DECL_ISUPPORTS_INHERITED
 
   PlaceholderTransaction(EditorBase& aEditorBase, nsIAtom* aName,
@@ -59,6 +63,11 @@ public:
 
   NS_IMETHOD Commit() override;
 
+  NS_IMETHOD_(PlaceholderTransaction*) AsPlaceholderTransaction() override
+  {
+    return this;
+  }
+
   nsresult RememberEndingSelection();
 
 protected:

editor/libeditor/TextEditor.cpp

@@ -872,7 +872,7 @@ TextEditor::UpdateIMEComposition(WidgetCompositionEvent* aCompsitionChangeEvent)
   //       of NotifiyEditorObservers(eNotifyEditorObserversOfEnd) or
   //       NotifiyEditorObservers(eNotifyEditorObserversOfCancel) which notifies
   //       TextComposition of a selection change.
-  MOZ_ASSERT(!mPlaceHolderBatch,
+  MOZ_ASSERT(!mPlaceholderBatch,
     "UpdateIMEComposition() must be called without place holder batch");
   TextComposition::CompositionChangeEventHandlingMarker
     compositionChangeEventHandlingMarker(mComposition, aCompsitionChangeEvent);

editor/libeditor/nsIAbsorbingTransaction.h

@@ -23,6 +23,7 @@ class nsIAtom;
 
 namespace mozilla {
 class EditorBase;
+class PlaceholderTransaction;
 class SelectionState;
 } // namespace mozilla
 
@@ -45,6 +46,9 @@ public:
   NS_IMETHOD ForwardEndBatchTo(nsIAbsorbingTransaction *aForwardingAddress)=0;
 
   NS_IMETHOD Commit()=0;
+
+  NS_IMETHOD_(mozilla::PlaceholderTransaction*)
+    AsPlaceholderTransaction() = 0;
 };
 
 NS_DEFINE_STATIC_IID_ACCESSOR(nsIAbsorbingTransaction,