EXPERIMENT TextIterator built on Layout NG offset mapping

third_party/WebKit/Source/core/editing/iterators/TextIteratorTextNodeHandler.cpp

Index: third_party/WebKit/Source/core/editing/iterators/TextIteratorTextNodeHandler.cpp
diff --git a/third_party/WebKit/Source/core/editing/iterators/TextIteratorTextNodeHandler.cpp b/third_party/WebKit/Source/core/editing/iterators/TextIteratorTextNodeHandler.cpp
index e4bf6aeffaf43c2e7c4fd68178a07ba42be38811..d786b02ab5eebd5ae8879c4176be1b47d3fc8830 100644
--- a/third_party/WebKit/Source/core/editing/iterators/TextIteratorTextNodeHandler.cpp
+++ b/third_party/WebKit/Source/core/editing/iterators/TextIteratorTextNodeHandler.cpp
@@ -6,10 +6,13 @@
 
 #include <algorithm>
 #include "core/dom/FirstLetterPseudoElement.h"
+#include "core/editing/VisibleUnits.h"
 #include "core/editing/iterators/TextIteratorTextState.h"
 #include "core/layout/LayoutTextFragment.h"
 #include "core/layout/line/InlineTextBox.h"
 #include "core/layout/line/RootInlineBox.h"
+#include "core/layout/ng/inline/ng_inline_node.h"
+#include "core/layout/ng/layout_ng_block_flow.h"
 
 namespace blink {
 
@@ -24,6 +27,11 @@ DEFINE_TRACE(TextIteratorTextNodeHandler) {
 }
 
 bool TextIteratorTextNodeHandler::HandleRemainingTextRuns() {
+  if (ng_block_flow_) {
+    HandleTextNodeInNGBlockFlow(*ng_block_flow_);
+    return text_state_->PositionNode();
+  }
+
   if (ShouldProceedToRemainingText())
     ProceedToRemainingText();
   // Handle remembered text box
@@ -120,18 +128,62 @@ void TextIteratorTextNodeHandler::HandlePreFormattedTextNode() {
   EmitText(text_node_, text_node_->GetLayoutObject(), run_start, run_end);
 }
 
+void TextIteratorTextNodeHandler::HandleTextNodeInNGBlockFlow(
+    const LayoutNGBlockFlow& block) {
+  if (block != ng_block_flow_) {
+    mapping_result_ = NGInlineNode(const_cast<LayoutNGBlockFlow*>(&block))
+                          .BuildOffsetMapping();
+    ng_block_flow_ = &block;
+  }
+
+  const LayoutObject* layout_object =
+      AssociatedLayoutObjectOf(*text_node_, offset_);
+
+  // Skip invisible content.
+  if (layout_object->Style()->Display() == EDisplay::kNone ||
+      (layout_object->Style()->Visibility() != EVisibility::kVisible &&
+       !IgnoresStyleVisibility())) {
+    offset_ = end_offset_;
+    return;
+  }
+
+  while (offset_ < end_offset_ && !text_state_->PositionNode()) {
+    const NGOffsetMappingUnit* unit =
+        mapping_result_.GetMappingUnitForDOMOffset(*text_node_, offset_);
+    // No more text on this node to emit.
+    if (!unit || static_cast<unsigned>(offset_) == unit->dom_end) {
+      offset_ = end_offset_;
+      return;
+    }
+
+    const unsigned run_end =
+        std::min(static_cast<unsigned>(end_offset_), unit->dom_end);
+    if (unit->type == NGOffsetMappingUnitType::kCollapsed) {
+      offset_ = run_end;
+      continue;
+    }
+
+    // TODO(xiaochengh): Handle EmitsOriginalText.
+
+    String string =
+        NGInlineNode(const_cast<LayoutNGBlockFlow*>(ng_block_flow_)).Text();
+    if (behavior_.EmitsSpaceForNbsp())
+      string.Replace(kNoBreakSpaceCharacter, kSpaceCharacter);
+    const unsigned text_content_start = unit->DOMToTextContentOffset(offset_);
+    const unsigned text_content_end = unit->DOMToTextContentOffset(run_end);
+    text_state_->EmitText(text_node_, offset_, run_end, string,
+                          text_content_start, text_content_end);
+    offset_ = run_end;
+    return;
+  }
+}
+
 void TextIteratorTextNodeHandler::HandleTextNodeInRange(Text* node,
                                                         int start_offset,
                                                         int end_offset) {
   DCHECK(node);
   DCHECK_GE(start_offset, 0);
-
-  // TODO(editing-dev): Add the following DCHECK once we stop assuming equal
-  // number of code units in DOM string and LayoutText::GetText(). Currently
-  // violated by
-  // - external/wpt/innerText/getter.html
-  // - fast/css/case-transform.html
-  // DCHECK_LE(end_offset, static_cast<int>(node->data().length()));
+  DCHECK_LE(end_offset, static_cast<int>(node->data().length()));
 
   // TODO(editing-dev): Stop passing in |start_offset == end_offset|.
   DCHECK_LE(start_offset, end_offset);
@@ -143,6 +195,13 @@ void TextIteratorTextNodeHandler::HandleTextNodeInRange(Text* node,
   first_letter_text_ = nullptr;
 
   LayoutText* layout_object = text_node_->GetLayoutObject();
+  const LayoutBox* enclosing_box = layout_object->EnclosingBox();
+  if (enclosing_box && enclosing_box->IsLayoutNGBlockFlow()) {
+    HandleTextNodeInNGBlockFlow(ToLayoutNGBlockFlow(*enclosing_box));
+    return;
+  }
+  ng_block_flow_ = nullptr;
+
   String str = layout_object->GetText();
 
   // handle pre-formatted text
@@ -189,9 +248,7 @@ void TextIteratorTextNodeHandler::HandleTextNodeInRange(Text* node,
 
 void TextIteratorTextNodeHandler::HandleTextNodeStartFrom(Text* node,
                                                           int start_offset) {
-  HandleTextNodeInRange(node, start_offset,
-                        node->GetLayoutObject()->TextStartOffset() +
-                            node->GetLayoutObject()->GetText().length());
+  HandleTextNodeInRange(node, start_offset, node->data().length());
 }
 
 void TextIteratorTextNodeHandler::HandleTextNodeEndAt(Text* node,
@@ -411,6 +468,8 @@ bool TextIteratorTextNodeHandler::FixLeadingWhiteSpaceForReplacedElement(
     Node* parent) {
   // This is a hacky way for white space fixup in legacy layout. With LayoutNG,
   // we can get rid of this function.
+  if (ng_block_flow_)
+    return false;
 
   if (behavior_.CollapseTrailingSpace()) {
     if (text_node_) {