Bug 1649931 - Part 3: Add nsIFrameEnumerator::Traverse() r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D81954

dom/base/nsFocusManager.cpp

@@ -3901,20 +3901,14 @@ nsresult nsFocusManager::GetNextTabbableContent(
         } else if (aRootContent->IsFocusable()) {
           frameTraversal->Next();
         }
-        frame = static_cast<nsIFrame*>(frameTraversal->CurrentItem());
+        frame = frameTraversal->CurrentItem();
       } else if (getNextFrame &&
                  (!iterStartContent ||
                   !iterStartContent->IsHTMLElement(nsGkAtoms::area))) {
         // Need to do special check in case we're in an imagemap which has
         // multiple content nodes per frame, so don't skip over the starting
         // frame.
-        if (aForward) {
-          frameTraversal->Next();
-        } else {
-          frameTraversal->Prev();
-        }
-
-        frame = static_cast<nsIFrame*>(frameTraversal->CurrentItem());
+        frame = frameTraversal->Traverse(aForward);
       }
     }
 

layout/base/nsIFrameTraversal.h

@@ -27,6 +27,15 @@ class nsIFrameEnumerator : public nsISupports {
 
   virtual void Last() = 0;
   virtual void Prev() = 0;
+
+  inline nsIFrame* Traverse(bool aForward) {
+    if (aForward) {
+      Next();
+    } else {
+      Prev();
+    }
+    return CurrentItem();
+  };
 };
 
 NS_DEFINE_STATIC_IID_ACCESSOR(nsIFrameEnumerator, NS_IFRAMEENUMERATOR_IID)

layout/generic/nsFrame.cpp

@@ -8111,8 +8111,7 @@ nsresult nsIFrame::GetNextPrevLineFromeBlockFrame(nsPresContext* aPresContext,
         if (aPos->mDirection == eDirNext && (resultFrame == nearStoppingFrame))
           break;
         // always try previous on THAT line if that fails go the other way
-        frameTraversal->Prev();
-        resultFrame = frameTraversal->CurrentItem();
+        resultFrame = frameTraversal->Traverse(/* aForward = */ false);
         if (!resultFrame) return NS_ERROR_FAILURE;
       }
 
@@ -8151,8 +8150,7 @@ nsresult nsIFrame::GetNextPrevLineFromeBlockFrame(nsPresContext* aPresContext,
         if (aPos->mDirection == eDirNext && (resultFrame == farStoppingFrame))
           break;
         // previous didnt work now we try "next"
-        frameTraversal->Next();
-        nsIFrame* tempFrame = frameTraversal->CurrentItem();
+        nsIFrame* tempFrame = frameTraversal->Traverse(/* aForward = */ true);
         if (!tempFrame) break;
         resultFrame = tempFrame;
       }
@@ -8871,9 +8869,15 @@ nsresult nsIFrame::GetFrameFromDirection(
   *aOutJumpedLine = false;
   *aOutMovedOverNonSelectableText = false;
 
-  nsresult result;
   nsPresContext* presContext = PresContext();
   bool needsVisualTraversal = aVisual && presContext->BidiEnabled();
+  nsCOMPtr<nsIFrameEnumerator> frameTraversal;
+  MOZ_TRY(NS_NewFrameTraversal(getter_AddRefs(frameTraversal), presContext,
+                               this, eLeaf, needsVisualTraversal,
+                               aScrollViewStop,
+                               true,  // aFollowOOFs
+                               false  // aSkipPopupChecks
+                               ));
 
   // Find the prev/next selectable frame
   bool selectable = false;
@@ -8899,21 +8903,7 @@ nsresult nsIFrame::GetFrameFromDirection(
         return NS_ERROR_FAILURE;  // we are done. cannot jump lines
     }
 
-    nsCOMPtr<nsIFrameEnumerator> frameTraversal;
-    result = NS_NewFrameTraversal(getter_AddRefs(frameTraversal), presContext,
-                                  traversedFrame, eLeaf, needsVisualTraversal,
-                                  aScrollViewStop,
-                                  true,  // aFollowOOFs
-                                  false  // aSkipPopupChecks
-    );
-    if (NS_FAILED(result)) return result;
-
-    if (aDirection == eDirNext)
-      frameTraversal->Next();
-    else
-      frameTraversal->Prev();
-
-    traversedFrame = frameTraversal->CurrentItem();
+    traversedFrame = frameTraversal->Traverse(aDirection == eDirNext);
     if (!traversedFrame) {
       return NS_ERROR_FAILURE;
     }

layout/generic/nsFrameSelection.cpp

@@ -1032,12 +1032,7 @@ nsresult nsFrameSelection::GetFrameFromLevel(nsIFrame* aFrameIn,
 
   do {
     *aFrameOut = foundFrame;
-    if (aDirection == eDirNext)
-      frameTraversal->Next();
-    else
-      frameTraversal->Prev();
-
-    foundFrame = frameTraversal->CurrentItem();
+    foundFrame = frameTraversal->Traverse(aDirection == eDirNext);
     if (!foundFrame) return NS_ERROR_FAILURE;
     foundLevel = foundFrame->GetEmbeddingLevel();