Add methods to Element that allow access to the parsed names in the

part= attribute.


R=hayato@chromium.org

Bug: 805271
Change-Id: Ie3ebecb3848b21d93189c6044d2c410490bb4ded
Reviewed-on: https://chromium-review.googlesource.com/958311
Commit-Queue: Fergal Daly <fergal@chromium.org>
Reviewed-by: Hayato Ito <hayato@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544387}

third_party/WebKit/Source/core/dom/Element.cpp

@@ -1541,6 +1541,9 @@ void Element::AttributeChanged(const AttributeModificationParams& params) {
     }
   } else if (name == HTMLNames::nameAttr) {
     SetHasName(!params.new_value.IsNull());
+  } else if (name == HTMLNames::partAttr) {
+    if (RuntimeEnabledFeatures::CSSPartPseudoElementEnabled())
+      EnsureElementRareData().SetPart(params.new_value);
   } else if (IsStyledElement()) {
     if (name == styleAttr) {
       StyleAttributeChanged(params.new_value, params.reason);
@@ -4807,4 +4810,21 @@ void Element::TraceWrappers(const ScriptWrappableVisitor* visitor) const {
   ContainerNode::TraceWrappers(visitor);
 }
 
+bool Element::HasPartName() const {
+  if (!RuntimeEnabledFeatures::CSSPartPseudoElementEnabled())
+    return false;
+  if (HasRareData()) {
+    if (auto* part_names = GetElementRareData()->PartNames()) {
+      return part_names->size() > 0;
+    }
+  }
+  return false;
+}
+
+const SpaceSplitString* Element::PartNames() const {
+  return RuntimeEnabledFeatures::CSSPartPseudoElementEnabled() && HasRareData()
+             ? GetElementRareData()->PartNames()
+             : nullptr;
+}
+
 }  // namespace blink

third_party/WebKit/Source/core/dom/Element.h

@@ -810,6 +810,9 @@ class CORE_EXPORT Element : public ContainerNode {
   const SpaceSplitString& ClassNames() const;
   bool HasClassName(const AtomicString& class_name) const;
 
+  bool HasPartName() const;
+  const SpaceSplitString* PartNames() const;
+
   ScrollOffset SavedLayerScrollOffset() const;
   void SetSavedLayerScrollOffset(const ScrollOffset&);
 

third_party/WebKit/Source/core/dom/ElementRareData.cpp

@@ -40,7 +40,7 @@ namespace blink {
 
 struct SameSizeAsElementRareData : NodeRareData {
   IntSize scroll_offset;
-  void* pointers_or_strings[3];
+  void* pointers_or_strings[4];
   Member<void*> members[14];
 };
 

third_party/WebKit/Source/core/dom/ElementRareData.h

@@ -35,6 +35,7 @@
 #include "core/dom/NodeRareData.h"
 #include "core/dom/PseudoElement.h"
 #include "core/dom/PseudoElementData.h"
+#include "core/dom/SpaceSplitString.h"
 #include "core/html/custom/CustomElementDefinition.h"
 #include "core/html/custom/V0CustomElementDefinition.h"
 #include "core/intersection_observer/ElementIntersectionObserverData.h"
@@ -97,6 +98,16 @@ class ElementRareData : public NodeRareData {
     class_list_ = class_list;
   }
 
+  void SetPart(const AtomicString part_names) {
+    if (!RuntimeEnabledFeatures::CSSPartPseudoElementEnabled())
+      return;
+    if (!part_names_) {
+      part_names_.reset(new SpaceSplitString());
+    }
+    part_names_->Set(part_names);
+  }
+  const SpaceSplitString* PartNames() const { return part_names_.get(); }
+
   DatasetDOMStringMap* Dataset() const { return dataset_.Get(); }
   void SetDataset(DatasetDOMStringMap* dataset) {
     dataset_ = dataset;
@@ -181,6 +192,7 @@ class ElementRareData : public NodeRareData {
   TraceWrapperMember<DatasetDOMStringMap> dataset_;
   TraceWrapperMember<ElementShadow> shadow_;
   TraceWrapperMember<DOMTokenList> class_list_;
+  std::unique_ptr<SpaceSplitString> part_names_;
   TraceWrapperMember<NamedNodeMap> attribute_map_;
   Member<AttrNodeList> attr_node_list_;
   Member<InlineCSSStyleDeclaration> cssom_wrapper_;

third_party/WebKit/Source/core/dom/ElementTest.cpp

@@ -344,4 +344,50 @@ TEST_F(ElementTest, GetBoundingClientRectForSVG) {
   EXPECT_EQ(IntRect(10, 100, 100, 71), svg_stroke->BoundsInViewport());
 }
 
+TEST_F(ElementTest, PartAttribute) {
+  Document& document = GetDocument();
+  SetBodyContent(R"HTML(
+    <span id='has_one_part' part='partname'></span>
+    <span id='has_two_parts' part='partname1 partname2'></span>
+    <span id='has_no_part'></span>
+  )HTML");
+
+  Element* has_one_part = document.getElementById("has_one_part");
+  Element* has_two_parts = document.getElementById("has_two_parts");
+  Element* has_no_part = document.getElementById("has_no_part");
+
+  ASSERT_TRUE(has_no_part);
+  ASSERT_TRUE(has_one_part);
+  ASSERT_TRUE(has_two_parts);
+
+  {
+    EXPECT_TRUE(has_one_part->HasPartName());
+    const SpaceSplitString* part_names = has_one_part->PartNames();
+    ASSERT_TRUE(part_names);
+    ASSERT_EQ(1UL, part_names->size());
+    ASSERT_EQ("partname", (*part_names)[0].Ascii());
+  }
+
+  {
+    EXPECT_TRUE(has_two_parts->HasPartName());
+    const SpaceSplitString* part_names = has_two_parts->PartNames();
+    ASSERT_TRUE(part_names);
+    ASSERT_EQ(2UL, part_names->size());
+    ASSERT_EQ("partname1", (*part_names)[0].Ascii());
+    ASSERT_EQ("partname2", (*part_names)[1].Ascii());
+  }
+
+  {
+    EXPECT_FALSE(has_no_part->HasPartName());
+    EXPECT_FALSE(has_no_part->PartNames());
+
+    // Now update the attribute value and make sure it's reflected.
+    has_no_part->setAttribute("part", "partname");
+    const SpaceSplitString* part_names = has_no_part->PartNames();
+    ASSERT_TRUE(part_names);
+    ASSERT_EQ(1UL, part_names->size());
+    ASSERT_EQ("partname", (*part_names)[0].Ascii());
+  }
+}
+
 }  // namespace blink

third_party/WebKit/Source/core/html/html_attribute_names.json5

@@ -298,6 +298,7 @@
     "onwheel",
     "open",
     "optimum",
+    "part",
     "pattern",
     "placeholder",
     "ping",