Introduce NGInlineCursor member functions to utilize in NGCartPosition

This patch Introduces |NGInlineCursor| member functions to utilize in
|NGCartPosition|[1]:
 - MoveToFirstLogicalLeaf()
 - MoveToPreviousLine()
 - Property getter
   * HasSoftWrapToNextLine()
   * IsGeneratedText()
   * IsText()
   * CurrentNode()

[1] http://crrev.com/c/1866101 Utilize NGInlineCursor in NGCaretPosition

Bug: 982194
Change-Id: I9f261ebe0fe680ddc98f39a44f3c1c9dd26ef3a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1868358
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Auto-Submit: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707309}

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

@@ -16,6 +16,7 @@ NGFragmentItem::NGFragmentItem(const NGPhysicalTextFragment& text)
       type_(kText),
       sub_type_(static_cast<unsigned>(text.TextType())),
       style_variant_(static_cast<unsigned>(text.StyleVariant())),
+      is_generated_text_(text.IsGeneratedText()),
       is_hidden_for_paint_(false),
       text_direction_(static_cast<unsigned>(text.ResolvedDirection())) {
   DCHECK_LE(text_.start_offset, text_.end_offset);
@@ -82,6 +83,13 @@ bool NGFragmentItem::IsAtomicInline() const {
   return false;
 }
 
+bool NGFragmentItem::IsGeneratedText() const {
+  if (Type() == kText || Type() == kGeneratedText)
+    return is_generated_text_;
+  NOTREACHED();
+  return false;
+}
+
 PhysicalRect NGFragmentItem::SelfInkOverflow() const {
   // TODO(kojii): Implement.
   return LocalRect();

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

@@ -238,6 +238,17 @@ class CORE_EXPORT NGFragmentItem : public DisplayItemClient {
     return StyleVariant() == NGStyleVariant::kEllipsis;
   }
 
+  // Returns true if the text is generated (from, e.g., list marker,
+  // pseudo-element, ...) instead of from a DOM text node.
+  //  * CSS content         kText
+  //  * ellipsis            kGeneratedText
+  //  * first-letter-part   kText
+  //  * list marker         kGeneratedText
+  //  * soft hyphen         kGeneratedText
+  // TODO(yosin): When we implement |kGeneratedText|, we rename this function
+  // to avoid confliction with |kGeneratedText|.
+  bool IsGeneratedText() const;
+
   bool IsSymbolMarker() const {
     return TextType() == NGTextType::kSymbolMarker;
   }
@@ -324,6 +335,10 @@ class CORE_EXPORT NGFragmentItem : public DisplayItemClient {
   unsigned type_ : 2;           // ItemType
   unsigned sub_type_ : 3;       // NGTextType
   unsigned style_variant_ : 2;  // NGStyleVariant
+  // TODO(yosin): We'll remove |is_generated_text_| field when we construct
+  // |NGFragmentItem| without |NGPhysicalTextFragment| because usage of this
+  // varaible, IsGeneratedText(), is not hot.
+  unsigned is_generated_text_ : 1;  // NGPhysicalTextFragment::IsGenerated()
   unsigned is_hidden_for_paint_ : 1;
   // Note: For |TextItem| and |GeneratedTextItem|, |text_direction_| equals to
   // |ShapeResult::Direction()|.

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

@@ -9,6 +9,7 @@
 #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"
 #include "third_party/blink/renderer/core/paint/ng/ng_paint_fragment.h"
+#include "third_party/blink/renderer/core/paint/ng/ng_paint_fragment_traversal.h"
 
 namespace blink {
 
@@ -115,6 +116,12 @@ bool NGInlineCursor::HasChildren() const {
   return false;
 }
 
+bool NGInlineCursor::HasSoftWrapToNextLine() const {
+  DCHECK(IsLineBox());
+  const NGInlineBreakToken& break_token = CurrentInlineBreakToken();
+  return !break_token.IsFinished() && !break_token.IsForcedBreak();
+}
+
 bool NGInlineCursor::IsAtomicInline() const {
   if (current_paint_fragment_)
     return current_paint_fragment_->PhysicalFragment().IsAtomicInline();
@@ -133,6 +140,19 @@ bool NGInlineCursor::IsEllipsis() const {
   return false;
 }
 
+bool NGInlineCursor::IsGeneratedText() const {
+  if (current_paint_fragment_) {
+    if (auto* text_fragment = DynamicTo<NGPhysicalTextFragment>(
+            current_paint_fragment_->PhysicalFragment()))
+      return text_fragment->IsGeneratedText();
+    return false;
+  }
+  if (current_item_)
+    return current_item_->IsGeneratedText();
+  NOTREACHED();
+  return false;
+}
+
 bool NGInlineCursor::IsHiddenForPaint() const {
   if (current_paint_fragment_)
     return current_paint_fragment_->PhysicalFragment().IsHiddenForPaint();
@@ -176,6 +196,17 @@ bool NGInlineCursor::IsLineBreak() const {
   return false;
 }
 
+bool NGInlineCursor::IsText() const {
+  if (current_paint_fragment_)
+    return current_paint_fragment_->PhysicalFragment().IsText();
+  if (current_item_) {
+    return current_item_->Type() == NGFragmentItem::kText ||
+           current_item_->Type() == NGFragmentItem::kGeneratedText;
+  }
+  NOTREACHED();
+  return false;
+}
+
 bool NGInlineCursor::IsBeforeSoftLineBreak() const {
   if (IsLineBreak())
     return false;
@@ -248,6 +279,18 @@ const NGPhysicalBoxFragment* NGInlineCursor::CurrentBoxFragment() const {
   return nullptr;
 }
 
+const NGInlineBreakToken& NGInlineCursor::CurrentInlineBreakToken() const {
+  DCHECK(IsLineBox());
+  if (current_paint_fragment_) {
+    return To<NGInlineBreakToken>(
+        *To<NGPhysicalLineBoxFragment>(
+             current_paint_fragment_->PhysicalFragment())
+             .BreakToken());
+  }
+  DCHECK(current_item_);
+  return *current_item_->InlineBreakToken();
+}
+
 const LayoutObject* NGInlineCursor::CurrentLayoutObject() const {
   if (current_paint_fragment_)
     return current_paint_fragment_->GetLayoutObject();
@@ -257,6 +300,12 @@ const LayoutObject* NGInlineCursor::CurrentLayoutObject() const {
   return nullptr;
 }
 
+Node* NGInlineCursor::CurrentNode() const {
+  if (const LayoutObject* layout_object = CurrentLayoutObject())
+    return layout_object->GetNode();
+  return nullptr;
+}
+
 const PhysicalOffset NGInlineCursor::CurrentOffset() const {
   if (current_paint_fragment_)
     return current_paint_fragment_->InlineOffsetToContainerBox();
@@ -368,6 +417,9 @@ void NGInlineCursor::MoveTo(const LayoutObject& layout_object) {
 }
 
 void NGInlineCursor::MoveTo(const NGPaintFragment& paint_fragment) {
+  DCHECK(!fragment_items_);
+  if (!root_paint_fragment_)
+    root_paint_fragment_ = paint_fragment.Root();
   DCHECK(root_paint_fragment_);
   DCHECK(paint_fragment.IsDescendantOfNotSelf(*root_paint_fragment_))
       << paint_fragment << " " << root_paint_fragment_;
@@ -407,6 +459,21 @@ void NGInlineCursor::MoveToFirstChild() {
     MakeNull();
 }
 
+void NGInlineCursor::MoveToFirstLogicalLeaf() {
+  DCHECK(IsLineBox());
+  // 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())) {
+    while (TryToMoveToFirstChild())
+      continue;
+    return;
+  }
+  while (TryToMoveToLastChild())
+    continue;
+}
+
 void NGInlineCursor::MoveToLastChild() {
   DCHECK(CanHaveChildren());
   if (!TryToMoveToLastChild())
@@ -474,6 +541,24 @@ void NGInlineCursor::MoveToNextSkippingChildren() {
   MoveToNextItemSkippingChildren();
 }
 
+void NGInlineCursor::MoveToPreviousLine() {
+  DCHECK(IsLineBox());
+  if (current_paint_fragment_) {
+    // TODO(yosin): We should implement |PreviousLineOf()| here.
+    if (auto* paint_fragment =
+            NGPaintFragmentTraversal::PreviousLineOf(*current_paint_fragment_))
+      return MoveTo(*paint_fragment);
+    return MakeNull();
+  }
+  if (current_item_) {
+    do {
+      MoveToPreviousItem();
+    } while (IsNotNull() && !IsLineBox());
+    return;
+  }
+  NOTREACHED();
+}
+
 bool NGInlineCursor::TryToMoveToFirstChild() {
   if (!HasChildren())
     return false;

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

@@ -18,8 +18,10 @@ class LayoutInline;
 class LayoutObject;
 class NGFragmentItem;
 class NGFragmentItems;
+class NGInlineBreakToken;
 class NGPaintFragment;
 class NGPhysicalBoxFragment;
+class Node;
 struct PhysicalOffset;
 struct PhysicalRect;
 struct PhysicalSize;
@@ -73,6 +75,10 @@ class CORE_EXPORT NGInlineCursor {
   // True if fragment at the current position has children.
   bool HasChildren() const;
 
+  // True if current position has soft wrap to next line. It is error to call
+  // other than line.
+  bool HasSoftWrapToNextLine() const;
+
   // True if the current position is a atomic inline. It is error to call at
   // end.
   bool IsAtomicInline() const;
@@ -84,6 +90,10 @@ class CORE_EXPORT NGInlineCursor {
   // True if the current position is an ellipsis. It is error to call at end.
   bool IsEllipsis() const;
 
+  // True if the current position is a generatd text. It is error to call at
+  // end.
+  bool IsGeneratedText() const;
+
   // True if the current position is hidden for paint. It is error to call at
   // end.
   bool IsHiddenForPaint() const;
@@ -94,6 +104,9 @@ class CORE_EXPORT NGInlineCursor {
   // True if the current position is a line break. It is error to call at end.
   bool IsLineBreak() const;
 
+  // True if the current position is a text. It is error to call at end.
+  bool IsText() const;
+
   // |Current*| functions return an object for the current position.
   const NGFragmentItem* CurrentItem() const { return current_item_; }
   const NGPaintFragment* CurrentPaintFragment() const {
@@ -104,6 +117,7 @@ class CORE_EXPORT NGInlineCursor {
   TextDirection CurrentBaseDirection() const;
   const NGPhysicalBoxFragment* CurrentBoxFragment() const;
   const LayoutObject* CurrentLayoutObject() const;
+  Node* CurrentNode() 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.
@@ -140,6 +154,10 @@ class CORE_EXPORT NGInlineCursor {
   // See also |TryToMoveToFirstChild()|.
   void MoveToFirstChild();
 
+  // Move to first logical leaf of current line box. If current line box has
+  // no children, curosr becomes null.
+  void MoveToFirstLogicalLeaf();
+
   // Move to last child of current container box. If the current position is
   // at fragment without children, this cursor points nothing.
   // See also |TryToMoveToFirstChild()|.
@@ -162,6 +180,10 @@ class CORE_EXPORT NGInlineCursor {
   // Same as |MoveToNext| except that this skips children even if they exist.
   void MoveToNextSkippingChildren();
 
+  // Move the current position to previous line. It is error to call other than
+  // line box.
+  void MoveToPreviousLine();
+
   // Returns true if the current position moves to first child.
   bool TryToMoveToFirstChild();
 
@@ -174,6 +196,9 @@ class CORE_EXPORT NGInlineCursor {
  private:
   using ItemsSpan = base::span<const std::unique_ptr<NGFragmentItem>>;
 
+  // Returns break token for line box. It is error to call other than line box.
+  const NGInlineBreakToken& CurrentInlineBreakToken() 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;

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

@@ -135,6 +135,88 @@ TEST_P(NGInlineCursorTest, FirstChild2) {
   EXPECT_FALSE(cursor.TryToMoveToFirstChild());
 }
 
+TEST_P(NGInlineCursorTest, FirstLastLogicalLeafInSimpleText) {
+  // TDOO(yosin): Remove <style> once NGFragmentItem don't do culled inline.
+  InsertStyleElement("b { background: gray; }");
+  NGInlineCursor cursor =
+      SetupCursor("<div id=root><b>first</b><b>middle</b><b>last</b></div>");
+
+  NGInlineCursor first_logical_leaf(cursor);
+  first_logical_leaf.MoveToFirstLogicalLeaf();
+  EXPECT_EQ("first", ToDebugString(first_logical_leaf));
+
+  NGInlineCursor last_logical_leaf(cursor);
+  last_logical_leaf.MoveToLastLogicalLeaf();
+  EXPECT_EQ("last", ToDebugString(last_logical_leaf));
+}
+
+TEST_P(NGInlineCursorTest, FirstLastLogicalLeafInRtlText) {
+  // TDOO(yosin): Remove <style> once NGFragmentItem don't do culled inline.
+  InsertStyleElement("b { background: gray; }");
+  NGInlineCursor cursor = SetupCursor(
+      "<bdo id=root dir=rtl style=display:block>"
+      "<b>first</b><b>middle</b><b>last</b>"
+      "</bdo>");
+
+  NGInlineCursor first_logical_leaf(cursor);
+  first_logical_leaf.MoveToFirstLogicalLeaf();
+  EXPECT_EQ("first", ToDebugString(first_logical_leaf));
+
+  NGInlineCursor last_logical_leaf(cursor);
+  last_logical_leaf.MoveToLastLogicalLeaf();
+  EXPECT_EQ("last", ToDebugString(last_logical_leaf));
+}
+
+TEST_P(NGInlineCursorTest, FirstLastLogicalLeafInTextAsDeepDescendants) {
+  // TDOO(yosin): Remove <style> once NGFragmentItem don't do culled inline.
+  InsertStyleElement("b { background: gray; }");
+  NGInlineCursor cursor = SetupCursor(
+      "<div id=root>"
+      "<b><b>first</b>ABC</b>"
+      "<b>middle</b>"
+      "<b>DEF<b>last</b></b>"
+      "</div>");
+
+  NGInlineCursor first_logical_leaf(cursor);
+  first_logical_leaf.MoveToFirstLogicalLeaf();
+  EXPECT_EQ("first", ToDebugString(first_logical_leaf));
+
+  NGInlineCursor last_logical_leaf(cursor);
+  last_logical_leaf.MoveToLastLogicalLeaf();
+  EXPECT_EQ("last", ToDebugString(last_logical_leaf));
+}
+
+TEST_P(NGInlineCursorTest, FirstLastLogicalLeafWithInlineBlock) {
+  InsertStyleElement("b { display: inline-block; }");
+  NGInlineCursor cursor = SetupCursor(
+      "<div id=root>"
+      "<b id=first>first</b>middle<b id=last>last</b>"
+      "</div>");
+
+  NGInlineCursor first_logical_leaf(cursor);
+  first_logical_leaf.MoveToFirstLogicalLeaf();
+  EXPECT_EQ("#first", ToDebugString(first_logical_leaf))
+      << "stop at inline-block";
+
+  NGInlineCursor last_logical_leaf(cursor);
+  last_logical_leaf.MoveToLastLogicalLeaf();
+  EXPECT_EQ("#last", ToDebugString(last_logical_leaf))
+      << "stop at inline-block";
+}
+
+TEST_P(NGInlineCursorTest, FirstLastLogicalLeafWithImages) {
+  NGInlineCursor cursor =
+      SetupCursor("<div id=root><img id=first>middle<img id=last></div>");
+
+  NGInlineCursor first_logical_leaf(cursor);
+  first_logical_leaf.MoveToFirstLogicalLeaf();
+  EXPECT_EQ("#first", ToDebugString(first_logical_leaf));
+
+  NGInlineCursor last_logical_leaf(cursor);
+  last_logical_leaf.MoveToLastLogicalLeaf();
+  EXPECT_EQ("#last", ToDebugString(last_logical_leaf));
+}
+
 TEST_P(NGInlineCursorTest, LastChild) {
   // TDOO(yosin): Remove <style> once NGFragmentItem don't do culled inline.
   InsertStyleElement("a, b { background: gray; }");
@@ -285,4 +367,25 @@ TEST_P(NGInlineCursorTest, EmptyOutOfFlow) {
   EXPECT_THAT(list, ElementsAre());
 }
 
+TEST_P(NGInlineCursorTest, PreviousLine) {
+  NGInlineCursor cursor = SetupCursor("<div id=root>abc<br>xyz</div>");
+  NGInlineCursor line1(cursor);
+  while (line1 && !line1.IsLineBox())
+    line1.MoveToNext();
+  ASSERT_TRUE(line1.IsNotNull());
+  NGInlineCursor line2(line1);
+  line2.MoveToNext();
+  while (line2 && !line2.IsLineBox())
+    line2.MoveToNext();
+  ASSERT_NE(line1, line2);
+
+  NGInlineCursor should_be_null(line1);
+  should_be_null.MoveToPreviousLine();
+  EXPECT_TRUE(should_be_null.IsNull());
+
+  NGInlineCursor should_be_line1(line2);
+  should_be_line1.MoveToPreviousLine();
+  EXPECT_EQ(line1, should_be_line1);
+}
+
 }  // namespace blink