Source/WebCore/dom/NodeRareData.h - WebKit - Git at Google

 /*
  * Copyright (C) 2008-2019 Apple Inc. All rights reserved.
  * Copyright (C) 2008 David Smith <catfish.man@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */

 #pragma once

 #include "ChildNodeList.h"
 #include "CommonAtomStrings.h"
 #include "HTMLCollection.h"
 #include "MutationObserverRegistration.h"
 #include "QualifiedName.h"
 #include "TagCollection.h"
 #include <wtf/HashSet.h>
 #include <wtf/StdLibExtras.h>

 namespace WebCore {

 class LabelsNodeList;
 class LiveNodeList;
 class NameNodeList;
 class RadioNodeList;

 template<typename ListType> struct NodeListTypeIdentifier;

 DECLARE_ALLOCATOR_WITH_HEAP_IDENTIFIER(NodeListsNodeData);
 class NodeListsNodeData {
     WTF_MAKE_NONCOPYABLE(NodeListsNodeData);
     WTF_MAKE_STRUCT_FAST_ALLOCATED_WITH_HEAP_IDENTIFIER(NodeListsNodeData);
 public:
     NodeListsNodeData() = default;

     void clearChildNodeListCache()
     {
         if (m_childNodeList)
             m_childNodeList->invalidateCache();
     }

     Ref<ChildNodeList> ensureChildNodeList(ContainerNode& node)
     {
         ASSERT(!m_emptyChildNodeList);
         if (m_childNodeList)
             return *m_childNodeList;
         auto list = ChildNodeList::create(node);
         m_childNodeList = list.ptr();
         return list;
     }

     void removeChildNodeList(ChildNodeList* list)
     {
         ASSERT(m_childNodeList == list);
         if (deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(list->ownerNode()))
             return;
         m_childNodeList = nullptr;
     }

     Ref<EmptyNodeList> ensureEmptyChildNodeList(Node& node)
     {
         ASSERT(!m_childNodeList);
         if (m_emptyChildNodeList)
             return *m_emptyChildNodeList;
         auto list = EmptyNodeList::create(node);
         m_emptyChildNodeList = list.ptr();
         return list;
     }

     void removeEmptyChildNodeList(EmptyNodeList* list)
     {
         ASSERT(m_emptyChildNodeList == list);
         if (deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(list->ownerNode()))
             return;
         m_emptyChildNodeList = nullptr;
     }

     struct NodeListCacheMapEntryHash {
         static unsigned hash(const std::pair<unsigned char, AtomString>& entry)
         {
             return DefaultHash<AtomString>::hash(entry.second) + entry.first;
         }
         static bool equal(const std::pair<unsigned char, AtomString>& a, const std::pair<unsigned char, AtomString>& b) { return a.first == b.first && DefaultHash<AtomString>::equal(a.second, b.second); }
         static const bool safeToCompareToEmptyOrDeleted = DefaultHash<AtomString>::safeToCompareToEmptyOrDeleted;
     };

     using NodeListCacheMap = HashMap<std::pair<unsigned char, AtomString>, LiveNodeList*, NodeListCacheMapEntryHash>;
     using CollectionCacheMap = HashMap<std::pair<unsigned char, AtomString>, HTMLCollection*, NodeListCacheMapEntryHash>;
     using TagCollectionNSCache = HashMap<QualifiedName, TagCollectionNS*>;

     template<typename T, typename ContainerType>
     ALWAYS_INLINE Ref<T> addCacheWithAtomName(ContainerType& container, const AtomString& name)
     {
         auto result = m_atomNameCaches.fastAdd(namedNodeListKey<T>(name), nullptr);
         if (!result.isNewEntry)
             return static_cast<T&>(*result.iterator->value);

         auto list = T::create(container, name);
         result.iterator->value = &list.get();
         return list;
     }

     ALWAYS_INLINE Ref<TagCollectionNS> addCachedTagCollectionNS(ContainerNode& node, const AtomString& namespaceURI, const AtomString& localName)
     {
         auto result = m_tagCollectionNSCache.fastAdd(QualifiedName { nullAtom(), localName, namespaceURI }, nullptr);
         if (!result.isNewEntry)
             return *result.iterator->value;

         auto list = TagCollectionNS::create(node, namespaceURI, localName);
         result.iterator->value = list.ptr();
         return list;
     }

     template<typename T, typename ContainerType>
     ALWAYS_INLINE Ref<T> addCachedCollection(ContainerType& container, CollectionType collectionType, const AtomString& name)
     {
         auto result = m_cachedCollections.fastAdd(namedCollectionKey(collectionType, name), nullptr);
         if (!result.isNewEntry)
             return static_cast<T&>(*result.iterator->value);

         auto list = T::create(container, collectionType, name);
         result.iterator->value = &list.get();
         return list;
     }

     template<typename T, typename ContainerType>
     ALWAYS_INLINE Ref<T> addCachedCollection(ContainerType& container, CollectionType collectionType)
     {
         auto result = m_cachedCollections.fastAdd(namedCollectionKey(collectionType, starAtom()), nullptr);
         if (!result.isNewEntry)
             return static_cast<T&>(*result.iterator->value);

         auto list = T::create(container, collectionType);
         result.iterator->value = &list.get();
         return list;
     }

     template<typename T>
     T* cachedCollection(CollectionType collectionType)
     {
         return static_cast<T*>(m_cachedCollections.get(namedCollectionKey(collectionType, starAtom())));
     }

     template<typename NodeListType>
     void removeCacheWithAtomName(NodeListType& list, const AtomString& name)
     {
         ASSERT(&list == m_atomNameCaches.get(namedNodeListKey<NodeListType>(name)));
         if (deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(list.ownerNode()))
             return;
         m_atomNameCaches.remove(namedNodeListKey<NodeListType>(name));
     }

     void removeCachedTagCollectionNS(HTMLCollection& collection, const AtomString& namespaceURI, const AtomString& localName)
     {
         QualifiedName name(nullAtom(), localName, namespaceURI);
         ASSERT(&collection == m_tagCollectionNSCache.get(name));
         if (deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(collection.ownerNode()))
             return;
         m_tagCollectionNSCache.remove(name);
     }

     void removeCachedCollection(HTMLCollection* collection, const AtomString& name = starAtom())
     {
         ASSERT(collection == m_cachedCollections.get(namedCollectionKey(collection->type(), name)));
         if (deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(collection->ownerNode()))
             return;
         m_cachedCollections.remove(namedCollectionKey(collection->type(), name));
     }

     void invalidateCaches();
     void invalidateCachesForAttribute(const QualifiedName& attrName);

     void adoptTreeScope()
     {
         invalidateCaches();
     }

     void adoptDocument(Document& oldDocument, Document& newDocument)
     {
         if (&oldDocument == &newDocument) {
             invalidateCaches();
             return;
         }

         for (auto& cache : m_atomNameCaches.values())
             cache->invalidateCacheForDocument(oldDocument);

         for (auto& list : m_tagCollectionNSCache.values()) {
             ASSERT(!list->isRootedAtTreeScope());
             list->invalidateCacheForDocument(oldDocument);
         }

         for (auto& collection : m_cachedCollections.values())
             collection->invalidateCacheForDocument(oldDocument);
     }

 private:
     std::pair<unsigned char, AtomString> namedCollectionKey(CollectionType type, const AtomString& name)
     {
         return std::pair<unsigned char, AtomString>(type, name);
     }

     template<typename NodeListType>
     std::pair<unsigned char, AtomString> namedNodeListKey(const AtomString& name)
     {
         return std::pair<unsigned char, AtomString>(NodeListTypeIdentifier<NodeListType>::value(), name);
     }

     bool deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(Node&);

     // These two are currently mutually exclusive and could be unioned. Not very important as this class is large anyway.
     ChildNodeList* m_childNodeList { nullptr };
     EmptyNodeList* m_emptyChildNodeList { nullptr };

     NodeListCacheMap m_atomNameCaches;
     TagCollectionNSCache m_tagCollectionNSCache;
     CollectionCacheMap m_cachedCollections;
 };

 class NodeMutationObserverData {
     WTF_MAKE_NONCOPYABLE(NodeMutationObserverData); WTF_MAKE_FAST_ALLOCATED;
 public:
     Vector<std::unique_ptr<MutationObserverRegistration>> registry;
     HashSet<MutationObserverRegistration*> transientRegistry;

     NodeMutationObserverData() { }
 };

 DECLARE_ALLOCATOR_WITH_HEAP_IDENTIFIER(NodeRareData);
 class NodeRareData {
     WTF_MAKE_NONCOPYABLE(NodeRareData);
     WTF_MAKE_STRUCT_FAST_ALLOCATED_WITH_HEAP_IDENTIFIER(NodeRareData);
 public:
 #if defined(DUMP_NODE_STATISTICS) && DUMP_NODE_STATISTICS
     enum class UseType : uint32_t {
         NodeList = 1 << 0,
         MutationObserver = 1 << 1,
         TabIndex = 1 << 2,
         ScrollingPosition = 1 << 3,
         ComputedStyle = 1 << 4,
         Dataset = 1 << 5,
         ClassList = 1 << 6,
         ShadowRoot = 1 << 7,
         CustomElementQueue = 1 << 8,
         AttributeMap = 1 << 9,
         InteractionObserver = 1 << 10,
         ResizeObserver = 1 << 11,
         Animations = 1 << 12,
         PseudoElements = 1 << 13,
         StyleMap = 1 << 14,
         PartList = 1 << 15,
         PartNames = 1 << 16,
         Nonce = 1 << 17,
         ComputedStyleMap = 1 << 18,
         ExplicitlySetAttrElementsMap = 1 << 19,
     };
 #endif

     enum class Type { Element, Node };

     NodeRareData(Type type = Type::Node)
         : m_isElementRareData(type == Type::Element)
     {
     }

     bool isElementRareData() { return m_isElementRareData; }

     void clearNodeLists() { m_nodeLists = nullptr; }
     NodeListsNodeData* nodeLists() const { return m_nodeLists.get(); }
     NodeListsNodeData& ensureNodeLists()
     {
         if (!m_nodeLists)
             m_nodeLists = makeUnique<NodeListsNodeData>();
         return *m_nodeLists;
     }

     NodeMutationObserverData* mutationObserverData() { return m_mutationObserverData.get(); }
     NodeMutationObserverData& ensureMutationObserverData()
     {
         if (!m_mutationObserverData)
             m_mutationObserverData = makeUnique<NodeMutationObserverData>();
         return *m_mutationObserverData;
     }

 #if DUMP_NODE_STATISTICS
     OptionSet<UseType> useTypes() const
     {
         OptionSet<UseType> result;
         if (m_nodeLists)
             result.add(UseType::NodeList);
         if (m_mutationObserverData)
             result.add(UseType::MutationObserver);
         return result;
     }
 #endif

 protected:
     // Used by ElementRareData. Defined here for better packing in 64-bit.
     int m_unusualTabIndex { 0 };
     unsigned short m_childIndex { 0 };

 private:
     bool m_isElementRareData;

     std::unique_ptr<NodeListsNodeData> m_nodeLists;
     std::unique_ptr<NodeMutationObserverData> m_mutationObserverData;
 };

 template<> struct NodeListTypeIdentifier<NameNodeList> {
     static constexpr unsigned char value() { return 0; }
 };

 template<> struct NodeListTypeIdentifier<RadioNodeList> {
     static constexpr unsigned char value() { return 1; }
 };

 template<> struct NodeListTypeIdentifier<LabelsNodeList> {
     static constexpr unsigned char value() { return 2; }
 };

 inline bool NodeListsNodeData::deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(Node& ownerNode)
 {
     ASSERT(ownerNode.nodeLists() == this);
     size_t listsCount = (m_childNodeList ? 1 : 0)
         + (m_emptyChildNodeList ? 1 : 0)
         + m_atomNameCaches.size()
         + m_tagCollectionNSCache.size()
         + m_cachedCollections.size();
     if (listsCount != 1)
         return false;
     ownerNode.clearNodeLists();
     return true;
 }

 inline NodeRareData& Node::ensureRareData()
 {
     if (!hasRareData())
         materializeRareData();
     return *rareData();
 }

 } // namespace WebCore
	/*
	* Copyright (C) 2008-2019 Apple Inc. All rights reserved.
	* Copyright (C) 2008 David Smith <catfish.man@gmail.com>
	*
	* This library is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Library General Public
	* License as published by the Free Software Foundation; either
	* version 2 of the License, or (at your option) any later version.
	*
	* This library is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Library General Public License for more details.
	*
	* You should have received a copy of the GNU Library General Public License
	* along with this library; see the file COPYING.LIB. If not, write to
	* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
	* Boston, MA 02110-1301, USA.
	*
	*/

	#pragma once

	#include "ChildNodeList.h"
	#include "CommonAtomStrings.h"
	#include "HTMLCollection.h"
	#include "MutationObserverRegistration.h"
	#include "QualifiedName.h"
	#include "TagCollection.h"
	#include <wtf/HashSet.h>
	#include <wtf/StdLibExtras.h>

	namespace WebCore {

	class LabelsNodeList;
	class LiveNodeList;
	class NameNodeList;
	class RadioNodeList;

	template<typename ListType> struct NodeListTypeIdentifier;

	DECLARE_ALLOCATOR_WITH_HEAP_IDENTIFIER(NodeListsNodeData);
	class NodeListsNodeData {
	WTF_MAKE_NONCOPYABLE(NodeListsNodeData);
	WTF_MAKE_STRUCT_FAST_ALLOCATED_WITH_HEAP_IDENTIFIER(NodeListsNodeData);
	public:
	NodeListsNodeData() = default;

	void clearChildNodeListCache()
	{
	if (m_childNodeList)
	m_childNodeList->invalidateCache();
	}

	Ref<ChildNodeList> ensureChildNodeList(ContainerNode& node)
	{
	ASSERT(!m_emptyChildNodeList);
	if (m_childNodeList)
	return *m_childNodeList;
	auto list = ChildNodeList::create(node);
	m_childNodeList = list.ptr();
	return list;
	}

	void removeChildNodeList(ChildNodeList* list)
	{
	ASSERT(m_childNodeList == list);
	if (deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(list->ownerNode()))
	return;
	m_childNodeList = nullptr;
	}

	Ref<EmptyNodeList> ensureEmptyChildNodeList(Node& node)
	{
	ASSERT(!m_childNodeList);
	if (m_emptyChildNodeList)
	return *m_emptyChildNodeList;
	auto list = EmptyNodeList::create(node);
	m_emptyChildNodeList = list.ptr();
	return list;
	}

	void removeEmptyChildNodeList(EmptyNodeList* list)
	{
	ASSERT(m_emptyChildNodeList == list);
	if (deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(list->ownerNode()))
	return;
	m_emptyChildNodeList = nullptr;
	}

	struct NodeListCacheMapEntryHash {
	static unsigned hash(const std::pair<unsigned char, AtomString>& entry)
	{
	return DefaultHash<AtomString>::hash(entry.second) + entry.first;
	}
	static bool equal(const std::pair<unsigned char, AtomString>& a, const std::pair<unsigned char, AtomString>& b) { return a.first == b.first && DefaultHash<AtomString>::equal(a.second, b.second); }
	static const bool safeToCompareToEmptyOrDeleted = DefaultHash<AtomString>::safeToCompareToEmptyOrDeleted;
	};

	using NodeListCacheMap = HashMap<std::pair<unsigned char, AtomString>, LiveNodeList*, NodeListCacheMapEntryHash>;
	using CollectionCacheMap = HashMap<std::pair<unsigned char, AtomString>, HTMLCollection*, NodeListCacheMapEntryHash>;
	using TagCollectionNSCache = HashMap<QualifiedName, TagCollectionNS*>;

	template<typename T, typename ContainerType>
	ALWAYS_INLINE Ref<T> addCacheWithAtomName(ContainerType& container, const AtomString& name)
	{
	auto result = m_atomNameCaches.fastAdd(namedNodeListKey<T>(name), nullptr);
	if (!result.isNewEntry)
	return static_cast<T&>(*result.iterator->value);

	auto list = T::create(container, name);
	result.iterator->value = &list.get();
	return list;
	}

	ALWAYS_INLINE Ref<TagCollectionNS> addCachedTagCollectionNS(ContainerNode& node, const AtomString& namespaceURI, const AtomString& localName)
	{
	auto result = m_tagCollectionNSCache.fastAdd(QualifiedName { nullAtom(), localName, namespaceURI }, nullptr);
	if (!result.isNewEntry)
	return *result.iterator->value;

	auto list = TagCollectionNS::create(node, namespaceURI, localName);
	result.iterator->value = list.ptr();
	return list;
	}

	template<typename T, typename ContainerType>
	ALWAYS_INLINE Ref<T> addCachedCollection(ContainerType& container, CollectionType collectionType, const AtomString& name)
	{
	auto result = m_cachedCollections.fastAdd(namedCollectionKey(collectionType, name), nullptr);
	if (!result.isNewEntry)
	return static_cast<T&>(*result.iterator->value);

	auto list = T::create(container, collectionType, name);
	result.iterator->value = &list.get();
	return list;
	}

	template<typename T, typename ContainerType>
	ALWAYS_INLINE Ref<T> addCachedCollection(ContainerType& container, CollectionType collectionType)
	{
	auto result = m_cachedCollections.fastAdd(namedCollectionKey(collectionType, starAtom()), nullptr);
	if (!result.isNewEntry)
	return static_cast<T&>(*result.iterator->value);

	auto list = T::create(container, collectionType);
	result.iterator->value = &list.get();
	return list;
	}

	template<typename T>
	T* cachedCollection(CollectionType collectionType)
	{
	return static_cast<T*>(m_cachedCollections.get(namedCollectionKey(collectionType, starAtom())));
	}

	template<typename NodeListType>
	void removeCacheWithAtomName(NodeListType& list, const AtomString& name)
	{
	ASSERT(&list == m_atomNameCaches.get(namedNodeListKey<NodeListType>(name)));
	if (deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(list.ownerNode()))
	return;
	m_atomNameCaches.remove(namedNodeListKey<NodeListType>(name));
	}

	void removeCachedTagCollectionNS(HTMLCollection& collection, const AtomString& namespaceURI, const AtomString& localName)
	{
	QualifiedName name(nullAtom(), localName, namespaceURI);
	ASSERT(&collection == m_tagCollectionNSCache.get(name));
	if (deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(collection.ownerNode()))
	return;
	m_tagCollectionNSCache.remove(name);
	}

	void removeCachedCollection(HTMLCollection* collection, const AtomString& name = starAtom())
	{
	ASSERT(collection == m_cachedCollections.get(namedCollectionKey(collection->type(), name)));
	if (deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(collection->ownerNode()))
	return;
	m_cachedCollections.remove(namedCollectionKey(collection->type(), name));
	}

	void invalidateCaches();
	void invalidateCachesForAttribute(const QualifiedName& attrName);

	void adoptTreeScope()
	{
	invalidateCaches();
	}

	void adoptDocument(Document& oldDocument, Document& newDocument)
	{
	if (&oldDocument == &newDocument) {
	invalidateCaches();
	return;
	}

	for (auto& cache : m_atomNameCaches.values())
	cache->invalidateCacheForDocument(oldDocument);

	for (auto& list : m_tagCollectionNSCache.values()) {
	ASSERT(!list->isRootedAtTreeScope());
	list->invalidateCacheForDocument(oldDocument);
	}

	for (auto& collection : m_cachedCollections.values())
	collection->invalidateCacheForDocument(oldDocument);
	}

	private:
	std::pair<unsigned char, AtomString> namedCollectionKey(CollectionType type, const AtomString& name)
	{
	return std::pair<unsigned char, AtomString>(type, name);
	}

	template<typename NodeListType>
	std::pair<unsigned char, AtomString> namedNodeListKey(const AtomString& name)
	{
	return std::pair<unsigned char, AtomString>(NodeListTypeIdentifier<NodeListType>::value(), name);
	}

	bool deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(Node&);

	// These two are currently mutually exclusive and could be unioned. Not very important as this class is large anyway.
	ChildNodeList* m_childNodeList { nullptr };
	EmptyNodeList* m_emptyChildNodeList { nullptr };

	NodeListCacheMap m_atomNameCaches;
	TagCollectionNSCache m_tagCollectionNSCache;
	CollectionCacheMap m_cachedCollections;
	};

	class NodeMutationObserverData {
	WTF_MAKE_NONCOPYABLE(NodeMutationObserverData); WTF_MAKE_FAST_ALLOCATED;
	public:
	Vector<std::unique_ptr<MutationObserverRegistration>> registry;
	HashSet<MutationObserverRegistration*> transientRegistry;

	NodeMutationObserverData() { }
	};

	DECLARE_ALLOCATOR_WITH_HEAP_IDENTIFIER(NodeRareData);
	class NodeRareData {
	WTF_MAKE_NONCOPYABLE(NodeRareData);
	WTF_MAKE_STRUCT_FAST_ALLOCATED_WITH_HEAP_IDENTIFIER(NodeRareData);
	public:
	#if defined(DUMP_NODE_STATISTICS) && DUMP_NODE_STATISTICS
	enum class UseType : uint32_t {
	NodeList = 1 << 0,
	MutationObserver = 1 << 1,
	TabIndex = 1 << 2,
	ScrollingPosition = 1 << 3,
	ComputedStyle = 1 << 4,
	Dataset = 1 << 5,
	ClassList = 1 << 6,
	ShadowRoot = 1 << 7,
	CustomElementQueue = 1 << 8,
	AttributeMap = 1 << 9,
	InteractionObserver = 1 << 10,
	ResizeObserver = 1 << 11,
	Animations = 1 << 12,
	PseudoElements = 1 << 13,
	StyleMap = 1 << 14,
	PartList = 1 << 15,
	PartNames = 1 << 16,
	Nonce = 1 << 17,
	ComputedStyleMap = 1 << 18,
	ExplicitlySetAttrElementsMap = 1 << 19,
	};
	#endif

	enum class Type { Element, Node };

	NodeRareData(Type type = Type::Node)
	: m_isElementRareData(type == Type::Element)
	{
	}

	bool isElementRareData() { return m_isElementRareData; }

	void clearNodeLists() { m_nodeLists = nullptr; }
	NodeListsNodeData* nodeLists() const { return m_nodeLists.get(); }
	NodeListsNodeData& ensureNodeLists()
	{
	if (!m_nodeLists)
	m_nodeLists = makeUnique<NodeListsNodeData>();
	return *m_nodeLists;
	}

	NodeMutationObserverData* mutationObserverData() { return m_mutationObserverData.get(); }
	NodeMutationObserverData& ensureMutationObserverData()
	{
	if (!m_mutationObserverData)
	m_mutationObserverData = makeUnique<NodeMutationObserverData>();
	return *m_mutationObserverData;
	}

	#if DUMP_NODE_STATISTICS
	OptionSet<UseType> useTypes() const
	{
	OptionSet<UseType> result;
	if (m_nodeLists)
	result.add(UseType::NodeList);
	if (m_mutationObserverData)
	result.add(UseType::MutationObserver);
	return result;
	}
	#endif

	protected:
	// Used by ElementRareData. Defined here for better packing in 64-bit.
	int m_unusualTabIndex { 0 };
	unsigned short m_childIndex { 0 };

	private:
	bool m_isElementRareData;

	std::unique_ptr<NodeListsNodeData> m_nodeLists;
	std::unique_ptr<NodeMutationObserverData> m_mutationObserverData;
	};

	template<> struct NodeListTypeIdentifier<NameNodeList> {
	static constexpr unsigned char value() { return 0; }
	};

	template<> struct NodeListTypeIdentifier<RadioNodeList> {
	static constexpr unsigned char value() { return 1; }
	};

	template<> struct NodeListTypeIdentifier<LabelsNodeList> {
	static constexpr unsigned char value() { return 2; }
	};

	inline bool NodeListsNodeData::deleteThisAndUpdateNodeRareDataIfAboutToRemoveLastList(Node& ownerNode)
	{
	ASSERT(ownerNode.nodeLists() == this);
	size_t listsCount = (m_childNodeList ? 1 : 0)
	+ (m_emptyChildNodeList ? 1 : 0)
	+ m_atomNameCaches.size()
	+ m_tagCollectionNSCache.size()
	+ m_cachedCollections.size();
	if (listsCount != 1)
	return false;
	ownerNode.clearNodeLists();
	return true;
	}

	inline NodeRareData& Node::ensureRareData()
	{
	if (!hasRareData())
	materializeRareData();
	return *rareData();
	}

	} // namespace WebCore