Make NGInlineCursor to support culled inline

This patch makes |NGInlineCursor| to support culled inline box to repalce
|NGInlineFragmentTraversal::SelfFragmentsOf()| with |NGInlineCursor| for
preparation of migrating |NGFragmentItem|.

Bug: 982194
Change-Id: I86d90dac19780af31defddebc09393a5ae836a3d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1855618
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Auto-Submit: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705852}

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

@@ -72,7 +72,8 @@ NGInlineCursor::NGInlineCursor(const NGInlineCursor& other)
       current_item_(other.current_item_),
       fragment_items_(other.fragment_items_),
       root_paint_fragment_(other.root_paint_fragment_),
-      current_paint_fragment_(other.current_paint_fragment_) {}
+      current_paint_fragment_(other.current_paint_fragment_),
+      layout_inline_(other.layout_inline_) {}
 
 bool NGInlineCursor::operator==(const NGInlineCursor& other) const {
   if (root_paint_fragment_) {
@@ -137,6 +138,12 @@ bool NGInlineCursor::IsHiddenForPaint() const {
   return false;
 }
 
+bool NGInlineCursor::IsInclusiveDescendantOf(
+    const LayoutObject& layout_object) const {
+  return CurrentLayoutObject() &&
+         CurrentLayoutObject()->IsDescendantOf(&layout_object);
+}
+
 bool NGInlineCursor::IsLastLineInInlineBlock() const {
   DCHECK(IsLineBox());
   if (!GetLayoutBlockFlow()->IsAtomicInlineLevel())
@@ -313,7 +320,7 @@ void NGInlineCursor::MakeNull() {
   NOTREACHED();
 }
 
-void NGInlineCursor::MoveTo(const LayoutObject& layout_object) {
+void NGInlineCursor::InternalMoveTo(const LayoutObject& layout_object) {
   DCHECK(layout_object.IsInLayoutNGInlineFormattingContext());
   if (root_paint_fragment_) {
     const auto fragments = NGPaintFragment::InlineFragmentsFor(&layout_object);
@@ -327,6 +334,19 @@ void NGInlineCursor::MoveTo(const LayoutObject& layout_object) {
     MoveToNextItem();
 }
 
+void NGInlineCursor::MoveTo(const LayoutObject& layout_object) {
+  InternalMoveTo(layout_object);
+  if (IsNotNull() || !layout_object.IsLayoutInline()) {
+    layout_inline_ = nullptr;
+    return;
+  }
+  // In case of |layout_object| is cullred inline.
+  layout_inline_ = ToLayoutInline(&layout_object);
+  MoveToFirst();
+  while (IsNotNull() && !IsInclusiveDescendantOf(layout_object))
+    MoveToNext();
+}
+
 void NGInlineCursor::MoveTo(const NGPaintFragment& paint_fragment) {
   DCHECK(root_paint_fragment_);
   DCHECK(paint_fragment.IsDescendantOfNotSelf(*root_paint_fragment_))
@@ -349,6 +369,18 @@ void NGInlineCursor::MoveToContainingLine() {
   NOTREACHED();
 }
 
+void NGInlineCursor::MoveToFirst() {
+  if (root_paint_fragment_) {
+    current_paint_fragment_ = root_paint_fragment_->FirstChild();
+    return;
+  }
+  if (IsItemCursor()) {
+    MoveToItem(items_.begin());
+    return;
+  }
+  NOTREACHED();
+}
+
 void NGInlineCursor::MoveToFirstChild() {
   DCHECK(CanHaveChildren());
   if (!TryToMoveToFirstChild())
@@ -363,8 +395,8 @@ void NGInlineCursor::MoveToLastChild() {
 
 void NGInlineCursor::MoveToLastLogicalLeaf() {
   DCHECK(IsLineBox());
-  // TODO(yosin): This isn't correct for mixed Bidi. Fix it. Besides, we should
-  // compute and store it during layout.
+  // TODO(yosin): This isn't correct for mixed Bidi. Fix it. Besides, we
+  // should compute and store it during layout.
   // TODO(yosin): We should check direction of each container instead of line
   // box. See also |NGPhysicalLineBoxFragment::LastLogicalLeaf()|.
   if (IsLtr(CurrentStyle().Direction())) {
@@ -383,6 +415,13 @@ void NGInlineCursor::MoveToNext() {
 }
 
 void NGInlineCursor::MoveToNextForSameLayoutObject() {
+  if (layout_inline_) {
+    // Move to next fragment in culled inline box undef |layout_inline_|.
+    do {
+      MoveToNext();
+    } while (IsNotNull() && !IsInclusiveDescendantOf(*layout_inline_));
+    return;
+  }
   if (current_paint_fragment_) {
     if (auto* paint_fragment =
             current_paint_fragment_->NextForSameLayoutObject())

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

@@ -13,8 +13,9 @@
 namespace blink {
 
 class ComputedStyle;
-class LayoutObject;
 class LayoutBlockFlow;
+class LayoutInline;
+class LayoutObject;
 class NGFragmentItem;
 class NGFragmentItems;
 class NGPaintFragment;
@@ -175,6 +176,10 @@ class CORE_EXPORT NGInlineCursor {
   // we'll call it "void cursor" instead of "null cursor".
   NGInlineCursor() = delete;
 
+  // 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;
+
   // True if the current position is a last line in inline block. It is error
   // to call at end or the current position is not line.
   bool IsLastLineInInlineBlock() const;
@@ -183,6 +188,12 @@ class CORE_EXPORT NGInlineCursor {
   // fragment, cursor moves to first/last child to parent has no children.
   void MakeNull();
 
+  // Move the cursor position to the first fragment in tree.
+  void MoveToFirst();
+
+  // Same as |MoveTo()| but not support culled inline.
+  void InternalMoveTo(const LayoutObject& layout_object);
+
   void SetRoot(const NGFragmentItems& items);
   void SetRoot(ItemsSpan items);
   void SetRoot(const NGPaintFragment& root_paint_fragment);
@@ -205,6 +216,9 @@ class CORE_EXPORT NGInlineCursor {
 
   const NGPaintFragment* root_paint_fragment_ = nullptr;
   const NGPaintFragment* current_paint_fragment_ = nullptr;
+
+  // Used in |MoveToNextForSameLayoutObject()| to support culled inline.
+  const LayoutInline* layout_inline_ = nullptr;
 };
 
 CORE_EXPORT std::ostream& operator<<(std::ostream&, const NGInlineCursor&);

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

@@ -82,12 +82,13 @@ TEST_P(NGInlineCursorTest, ContainingLine) {
   cursor.MoveToContainingLine();
   EXPECT_EQ(line1, cursor);
 
-  const LayoutObject& target = *GetLayoutObjectByElementId("target");
+  const LayoutInline& target =
+      ToLayoutInline(*GetLayoutObjectByElementId("target"));
   cursor.MoveTo(target);
   cursor.MoveToContainingLine();
   EXPECT_EQ(line1, cursor);
 
-  cursor.MoveTo(*target.SlowFirstChild());
+  cursor.MoveTo(*target.FirstChild());
   cursor.MoveToContainingLine();
   EXPECT_EQ(line1, cursor);
 
@@ -96,6 +97,20 @@ TEST_P(NGInlineCursorTest, ContainingLine) {
   EXPECT_EQ(line2, cursor);
 }
 
+TEST_P(NGInlineCursorTest, CulledInline) {
+  NGInlineCursor cursor =
+      SetupCursor("<div id=root><a><b>abc</b><br><i>xyz</i></a></div>");
+  const LayoutInline& layout_inline =
+      ToLayoutInline(*cursor.GetLayoutBlockFlow()->FirstChild());
+  cursor.MoveTo(layout_inline);
+  Vector<String> list;
+  while (cursor) {
+    list.push_back(ToDebugString(cursor));
+    cursor.MoveToNextForSameLayoutObject();
+  }
+  EXPECT_THAT(list, ElementsAre("abc", "", "xyz"));
+}
+
 TEST_P(NGInlineCursorTest, FirstChild) {
   // TDOO(yosin): Remove <style> once NGFragmentItem don't do culled inline.
   InsertStyleElement("a, b { background: gray; }");