Refactor SelectionModifier::ModifyExtendingForward()

This patch changes SelectionModifier::ModifyExtendingForward() to utilize
early-return style for improving readability.

Change-Id: I005c7064bacafca1ffaf2f805b31d5860f326389
Reviewed-on: https://chromium-review.googlesource.com/566203
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Yoichi Osato <yoichio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#485836}

third_party/WebKit/Source/core/editing/SelectionModifier.cpp

@@ -243,46 +243,48 @@ VisiblePosition SelectionModifier::ModifyExtendingRight(
   return AdjustBackwardPositionForUserSelectAll(pos);
 }
 
-VisiblePosition SelectionModifier::ModifyExtendingForward(
+VisiblePosition SelectionModifier::ModifyExtendingForwardInternal(
     TextGranularity granularity) {
-  VisiblePosition pos =
-      CreateVisiblePosition(selection_.Extent(), selection_.Affinity());
   switch (granularity) {
     case TextGranularity::kCharacter:
-      pos = NextPositionOf(pos, kCanSkipOverEditingBoundary);
-      break;
+      return NextPositionOf(
+          CreateVisiblePosition(selection_.Extent(), selection_.Affinity()),
+          kCanSkipOverEditingBoundary);
     case TextGranularity::kWord:
-      pos = NextWordPositionForPlatform(pos);
-      break;
+      return NextWordPositionForPlatform(
+          CreateVisiblePosition(selection_.Extent(), selection_.Affinity()));
     case TextGranularity::kSentence:
-      pos = NextSentencePosition(pos);
-      break;
+      return NextSentencePosition(
+          CreateVisiblePosition(selection_.Extent(), selection_.Affinity()));
     case TextGranularity::kLine:
-      pos = NextLinePosition(pos, LineDirectionPointForBlockDirectionNavigation(
-                                      selection_.Extent()));
-      break;
+      return NextLinePosition(
+          CreateVisiblePosition(selection_.Extent(), selection_.Affinity()),
+          LineDirectionPointForBlockDirectionNavigation(selection_.Extent()));
     case TextGranularity::kParagraph:
-      pos = NextParagraphPosition(
-          pos,
+      return NextParagraphPosition(
+          CreateVisiblePosition(selection_.Extent(), selection_.Affinity()),
           LineDirectionPointForBlockDirectionNavigation(selection_.Extent()));
-      break;
     case TextGranularity::kSentenceBoundary:
-      pos = EndOfSentence(EndForPlatform());
-      break;
+      return EndOfSentence(EndForPlatform());
     case TextGranularity::kLineBoundary:
-      pos = LogicalEndOfLine(EndForPlatform());
-      break;
+      return LogicalEndOfLine(EndForPlatform());
     case TextGranularity::kParagraphBoundary:
-      pos = EndOfParagraph(EndForPlatform());
+      return EndOfParagraph(EndForPlatform());
       break;
-    case TextGranularity::kDocumentBoundary:
-      pos = EndForPlatform();
+    case TextGranularity::kDocumentBoundary: {
+      const VisiblePosition& pos = EndForPlatform();
       if (IsEditablePosition(pos.DeepEquivalent()))
-        pos = EndOfEditableContent(pos);
-      else
-        pos = EndOfDocument(pos);
-      break;
+        return EndOfEditableContent(pos);
+      return EndOfDocument(pos);
     }
+  }
+  NOTREACHED() << static_cast<int>(granularity);
+  return VisiblePosition();
+}
+
+VisiblePosition SelectionModifier::ModifyExtendingForward(
+    TextGranularity granularity) {
+  const VisiblePosition pos = ModifyExtendingForwardInternal(granularity);
   if (DirectionOfEnclosingBlock() == TextDirection::kLtr)
     return AdjustForwardPositionForUserSelectAll(pos);
   return AdjustBackwardPositionForUserSelectAll(pos);

third_party/WebKit/Source/core/editing/SelectionModifier.h

@@ -69,6 +69,7 @@ class SelectionModifier {
   LayoutUnit LineDirectionPointForBlockDirectionNavigation(const Position&);
   VisiblePosition ModifyExtendingRight(TextGranularity);
   VisiblePosition ModifyExtendingForward(TextGranularity);
+  VisiblePosition ModifyExtendingForwardInternal(TextGranularity);
   VisiblePosition ModifyMovingRight(TextGranularity);
   VisiblePosition ModifyMovingForward(TextGranularity);
   VisiblePosition ModifyExtendingLeft(TextGranularity);