Introduce NGInlineCursor::CurrentBidiLevel()

This patch introduces |NGInlineCursor::CurrentBidiLevel()| with helper functions
for prepration of utilizing |NGInlineCursor| to |AbstractInlineTextBox|[1].

[1] http://crrev.com/c/1888242 Utilize NGInlineCursor for inline box traversal

Bug: 982194
Change-Id: I92f5aa918f27274cfd97dd2726bf95086d0b9ea8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1899240
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Auto-Submit: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712909}

third_party/blink/renderer/core/layout/ng/inline/ng_inline_cursor.cc

@@ -6,6 +6,7 @@
 
 #include "third_party/blink/renderer/core/editing/position_with_affinity.h"
 #include "third_party/blink/renderer/core/layout/layout_block_flow.h"
+#include "third_party/blink/renderer/core/layout/layout_text.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_fragment_items.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_physical_line_box_fragment.h"
 #include "third_party/blink/renderer/core/layout/ng/ng_physical_box_fragment.h"
@@ -357,6 +358,45 @@ TextDirection NGInlineCursor::CurrentBaseDirection() const {
   return TextDirection::kLtr;
 }
 
+UBiDiLevel NGInlineCursor::CurrentBidiLevel() const {
+  if (IsText()) {
+    const LayoutText& layout_text = *ToLayoutText(CurrentLayoutObject());
+    DCHECK(!layout_text.NeedsLayout()) << this;
+    const auto* const items = layout_text.GetNGInlineItems();
+    if (!items || items->size() == 0) {
+      // In case of <br>, <wbr>, text-combine-upright, etc.
+      return 0;
+    }
+    const auto& item = std::find_if(
+        items->begin(), items->end(), [this](const NGInlineItem& item) {
+          return item.StartOffset() <= CurrentTextStartOffset() &&
+                 item.EndOffset() >= CurrentTextEndOffset();
+        });
+    DCHECK(item != items->end()) << this;
+    return item->BidiLevel();
+  }
+
+  if (IsAtomicInline()) {
+    const NGPhysicalBoxFragment* fragmentainer =
+        CurrentLayoutObject()->ContainingBlockFlowFragment();
+    DCHECK(fragmentainer);
+    const LayoutBlockFlow& block_flow =
+        *To<LayoutBlockFlow>(fragmentainer->GetLayoutObject());
+    const Vector<NGInlineItem> items =
+        block_flow.GetNGInlineNodeData()->ItemsData(UsesFirstLineStyle()).items;
+    const LayoutObject* const layout_object = CurrentLayoutObject();
+    const auto* const item = std::find_if(
+        items.begin(), items.end(), [layout_object](const NGInlineItem& item) {
+          return item.GetLayoutObject() == layout_object;
+        });
+    DCHECK(item != items.end()) << this;
+    return item->BidiLevel();
+  }
+
+  NOTREACHED();
+  return 0;
+}
+
 const NGPhysicalBoxFragment* NGInlineCursor::CurrentBoxFragment() const {
   if (current_paint_fragment_) {
     return DynamicTo<NGPhysicalBoxFragment>(
@@ -441,6 +481,16 @@ const ComputedStyle& NGInlineCursor::CurrentStyle() const {
   return current_item_->Style();
 }
 
+NGStyleVariant NGInlineCursor::CurrentStyleVariant() const {
+  if (current_paint_fragment_)
+    return current_paint_fragment_->PhysicalFragment().StyleVariant();
+  return current_item_->StyleVariant();
+}
+
+bool NGInlineCursor::UsesFirstLineStyle() const {
+  return CurrentStyleVariant() == NGStyleVariant::kFirstLine;
+}
+
 unsigned NGInlineCursor::CurrentTextStartOffset() const {
   if (current_paint_fragment_) {
     return To<NGPhysicalTextFragment>(

third_party/blink/renderer/core/layout/ng/inline/ng_inline_cursor.h

@@ -5,6 +5,8 @@
 #ifndef THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_NG_INLINE_NG_INLINE_CURSOR_H_
 #define THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_NG_INLINE_NG_INLINE_CURSOR_H_
 
+#include <unicode/ubidi.h>
+
 #include "base/containers/span.h"
 #include "third_party/blink/renderer/core/core_export.h"
 #include "third_party/blink/renderer/core/editing/forward.h"
@@ -23,6 +25,7 @@ class NGFragmentItems;
 class NGInlineBreakToken;
 class NGPaintFragment;
 class NGPhysicalBoxFragment;
+enum class NGStyleVariant;
 class Node;
 struct PhysicalOffset;
 struct PhysicalRect;
@@ -156,6 +159,11 @@ class CORE_EXPORT NGInlineCursor {
   const NGPhysicalBoxFragment* CurrentBoxFragment() const;
   const LayoutObject* CurrentLayoutObject() const;
   Node* CurrentNode() const;
+
+  // Returns bidi level of current position. It is error to call other than
+  // text and atomic inline.
+  UBiDiLevel CurrentBidiLevel() const;
+
   // Returns text direction of current text or atomic inline. It is error to
   // call at other than text or atomic inline. Note: <span> doesn't have
   // reserved direction.
@@ -274,6 +282,10 @@ class CORE_EXPORT NGInlineCursor {
   // Returns break token for line box. It is error to call other than line box.
   const NGInlineBreakToken& CurrentInlineBreakToken() const;
 
+  // Returns style variant of the current position.
+  NGStyleVariant CurrentStyleVariant() const;
+  bool UsesFirstLineStyle() const;
+
   // True if current position is descendant or self of |layout_object|.
   // Note: This function is used for moving cursor in culled inline boxes.
   bool IsInclusiveDescendantOf(const LayoutObject& layout_object) const;
@@ -307,9 +319,9 @@ class CORE_EXPORT NGInlineCursor {
   void MoveToNextPaintFragment();
   void MoveToNextSiblingPaintFragment();
   void MoveToNextPaintFragmentSkippingChildren();
-
   void MoveToPreviousPaintFragment();
   void MoveToPreviousSiblingPaintFragment();
+
   ItemsSpan items_;
   ItemsSpan::iterator item_iter_;
   const NGFragmentItem* current_item_ = nullptr;

third_party/blink/renderer/core/layout/ng/inline/ng_inline_cursor_test.cc

@@ -43,11 +43,12 @@ class NGInlineCursorTest : public NGLayoutTest,
         cursor.GetLayoutBlockFlow()->GetNGInlineNodeData()->text_content;
     if (const LayoutObject* layout_object = cursor.CurrentLayoutObject()) {
       if (layout_object->IsText()) {
-        return text_content
-            .Substring(
-                cursor.CurrentTextStartOffset(),
-                cursor.CurrentTextEndOffset() - cursor.CurrentTextStartOffset())
-            .StripWhiteSpace();
+        String result = text_content
+                            .Substring(cursor.CurrentTextStartOffset(),
+                                       cursor.CurrentTextEndOffset() -
+                                           cursor.CurrentTextStartOffset())
+                            .StripWhiteSpace();
+        return result;
       }
       if (const Element* element =
               DynamicTo<Element>(layout_object->GetNode())) {
@@ -60,12 +61,70 @@ class NGInlineCursorTest : public NGLayoutTest,
 
     return "#null";
   }
+
+  Vector<String> ToDebugStringListWithBidiLevel(const NGInlineCursor& start) {
+    Vector<String> list;
+    for (NGInlineCursor cursor(start); cursor; cursor.MoveToNext())
+      list.push_back(ToDebugStringWithBidiLevel(cursor));
+    return list;
+  }
+
+  String ToDebugStringWithBidiLevel(const NGInlineCursor& cursor) {
+    if (!cursor.IsText() && !cursor.IsAtomicInline())
+      return ToDebugString(cursor);
+    StringBuilder result;
+    result.Append(ToDebugString(cursor));
+    result.Append(':');
+    result.AppendNumber(cursor.CurrentBidiLevel());
+    return result.ToString();
+  }
 };
 
 INSTANTIATE_TEST_SUITE_P(NGInlineCursorTest,
                          NGInlineCursorTest,
                          testing::Bool());
 
+TEST_P(NGInlineCursorTest, BidiLevelInlineBoxLTR) {
+  InsertStyleElement("b { display: inline-block; }");
+  NGInlineCursor cursor = SetupCursor(
+      "<div id=root dir=ltr>"
+      "abc<b id=def>def</b><bdo dir=rtl><b id=ghi>GHI</b></bdo>jkl</div>");
+  Vector<String> list = ToDebugStringListWithBidiLevel(cursor);
+  EXPECT_THAT(list, ElementsAre("#linebox", "abc:0", "#def:0",
+                                "LayoutInline BDO", "#ghi:1", "jkl:0"));
+}
+
+TEST_P(NGInlineCursorTest, BidiLevelInlineBoxRTL) {
+  InsertStyleElement("b { display: inline-block; }");
+  NGInlineCursor cursor = SetupCursor(
+      "<div id=root dir=rtl>"
+      "abc<b id=def>def</b><bdo dir=rtl><b id=ghi>GHI</b></bdo>jkl</div>");
+  Vector<String> list = ToDebugStringListWithBidiLevel(cursor);
+  EXPECT_THAT(list, ElementsAre("#linebox", "LayoutInline BDO", "#ghi:3",
+                                "jkl:2", "#def:1", "abc:2"));
+}
+
+TEST_P(NGInlineCursorTest, BidiLevelSimpleLTR) {
+  NGInlineCursor cursor = SetupCursor(
+      "<div id=root dir=ltr>"
+      "<bdo dir=rtl>GHI<bdo dir=ltr>abc</bdo>DEF</bdo><br>"
+      "123, jkl <bdo dir=rtl>MNO</bdo></div>");
+  Vector<String> list = ToDebugStringListWithBidiLevel(cursor);
+  EXPECT_THAT(list, ElementsAre("#linebox", "DEF:1", "abc:2", "GHI:1", ":0",
+                                "#linebox", "123, jkl:0", "MNO:1"));
+}
+
+TEST_P(NGInlineCursorTest, BidiLevelSimpleRTL) {
+  NGInlineCursor cursor = SetupCursor(
+      "<div id=root dir=rtl>"
+      "<bdo dir=rtl>GHI<bdo dir=ltr>abc</bdo>DEF</bdo><br>"
+      "123, jkl <bdo dir=rtl>MNO</bdo></div>");
+  Vector<String> list = ToDebugStringListWithBidiLevel(cursor);
+  EXPECT_THAT(
+      list, ElementsAre("#linebox", ":0", "DEF:3", "abc:4", "GHI:3", "#linebox",
+                        "MNO:3", ":1", "jkl:2", ",:1", "123:2"));
+}
+
 TEST_P(NGInlineCursorTest, GetLayoutBlockFlowWithScopedCursor) {
   NGInlineCursor line = SetupCursor("<div id=root>line1<br>line2</div>");
   ASSERT_TRUE(line.IsLineBox()) << line;

third_party/blink/renderer/core/layout/ng/inline/ng_inline_node_data.h

@@ -23,12 +23,13 @@ struct CORE_EXPORT NGInlineNodeData : NGInlineItemsData {
 
   bool IsBlockLevel() const { return is_block_level_; }
 
- private:
   const NGInlineItemsData& ItemsData(bool is_first_line) const {
     return !is_first_line || !first_line_items_
                ? (const NGInlineItemsData&)*this
                : *first_line_items_;
   }
+
+ private:
   void SetBaseDirection(TextDirection direction) {
     base_direction_ = static_cast<unsigned>(direction);
   }