Introduce ComputeSelectionMode in LayoutSelection

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights
  * reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 91 matching lines @@
 
   current_ = nullptr;
   return *this;
 }
 
 LayoutSelection::LayoutSelection(FrameSelection& frame_selection)
     : frame_selection_(&frame_selection),
       has_pending_selection_(false),
       paint_range_(SelectionPaintRange()) {}
 
-static bool ShouldShowBlockCursor(const FrameSelection& frame_selection,
-                                  const VisibleSelectionInFlatTree& selection) {
+enum class SelectionMode {
+  kNone,
+  kRange,
+  kBlockCursor,
+};
+static SelectionMode ComputeSelectionMode(

[yosin_UTC9, 2017/07/05 09:32:16]

nit: Could you add a blank line to separate |enum| declaration and function
definition?

+    const FrameSelection& frame_selection,
+    const VisibleSelectionInFlatTree& selection) {
+  if (selection.IsRange())
+    return SelectionMode::kRange;
   if (!frame_selection.ShouldShowBlockCursor())
-    return false;
-  if (selection.GetSelectionType() != SelectionType::kCaretSelection)
-    return false;
-  if (IsLogicalEndOfLine(selection.VisibleEnd()))
-    return false;
-  return true;
+    return SelectionMode::kNone;
+  if (IsLogicalEndOfLine(selection.VisibleStart()))
+    return SelectionMode::kNone;
+  return SelectionMode::kBlockCursor;
 }
 
 static EphemeralRangeInFlatTree CalcSelection(
     const FrameSelection& frame_selection) {
   const VisibleSelectionInFlatTree& original_selection =
       frame_selection.ComputeVisibleSelectionInFlatTree();
-
-  if (!ShouldShowBlockCursor(frame_selection, original_selection))
-    return {original_selection.Start(), original_selection.End()};
-
-  const PositionInFlatTree end_position = NextPositionOf(
-      original_selection.Start(), PositionMoveType::kGraphemeCluster);
-  const VisibleSelectionInFlatTree& block_cursor = CreateVisibleSelection(
-      SelectionInFlatTree::Builder()
-          .SetBaseAndExtent(original_selection.Start(), end_position)
-          .Build());
-  return {block_cursor.Start(), block_cursor.End()};
+  switch (ComputeSelectionMode(frame_selection, original_selection)) {
+    case SelectionMode::kNone:
+      return {};
+    case SelectionMode::kRange:
+      return {original_selection.Start(), original_selection.End()};
+    case SelectionMode::kBlockCursor: {
+      const PositionInFlatTree end_position = NextPositionOf(
+          original_selection.Start(), PositionMoveType::kGraphemeCluster);
+      const VisibleSelectionInFlatTree& block_cursor = CreateVisibleSelection(
+          SelectionInFlatTree::Builder()
+              .SetBaseAndExtent(original_selection.Start(), end_position)
+              .Build());
+      return {block_cursor.Start(), block_cursor.End()};
+    }
+  }
+  NOTREACHED();
+  return {};
 }
 
 // Objects each have a single selection rect to examine.
 using SelectedObjectMap = HashMap<LayoutObject*, SelectionState>;
 // Blocks contain selected objects and fill gaps between them, either on the
 // left, right, or in between lines and blocks.
 // In order to get the visual rect right, we have to examine left, middle, and
 // right rects individually, since otherwise the union of those rects might
 // remain the same even when changes have occurred.
 using SelectedBlockMap = HashMap<LayoutBlock*, SelectionState>;
@@ skipping 230 matching lines @@
 
     runner->SetShouldInvalidateSelection();
   }
 }
 
 DEFINE_TRACE(LayoutSelection) {
   visitor->Trace(frame_selection_);
 }
 
 }  // namespace blink