Move caching out of LiveNodeListBase and into a new CollectionIndexCache class

Source/core/dom/LiveNodeList.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  *
  * 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.
  *
  */
 
 #ifndef LiveNodeList_h
 #define LiveNodeList_h
 
 #include "HTMLNames.h"
 #include "core/dom/Document.h"
 #include "core/dom/NodeList.h"
+#include "core/html/CollectionIndexCache.h"
 #include "core/html/CollectionType.h"
 #include "wtf/Forward.h"
 #include "wtf/RefPtr.h"
 
 namespace WebCore {
 
 class Element;
 
 enum NodeListRootType {
     NodeListIsRootedAtNode,
     NodeListIsRootedAtDocument,
     NodeListIsRootedAtDocumentIfOwnerHasItemrefAttr,
 };
 
 class LiveNodeListBase {
 public:
     enum ItemAfterOverrideType {
         OverridesItemAfter,
         DoesNotOverrideItemAfter,
     };
 
     LiveNodeListBase(ContainerNode* ownerNode, NodeListRootType rootType, NodeListInvalidationType invalidationType,
         bool shouldOnlyIncludeDirectChildren, CollectionType collectionType, ItemAfterOverrideType itemAfterOverrideType)
         : m_ownerNode(ownerNode)
-        , m_cachedItem(0)
-        , m_isLengthCacheValid(false)
         , m_rootType(rootType)
         , m_invalidationType(invalidationType)
         , m_shouldOnlyIncludeDirectChildren(shouldOnlyIncludeDirectChildren)
         , m_collectionType(collectionType)
         , m_overridesItemAfter(itemAfterOverrideType == OverridesItemAfter)
     {
         ASSERT(m_ownerNode);
         ASSERT(m_rootType == static_cast<unsigned>(rootType));
         ASSERT(m_invalidationType == static_cast<unsigned>(invalidationType));
         ASSERT(m_collectionType == static_cast<unsigned>(collectionType));
         ASSERT(!m_overridesItemAfter || !isLiveNodeListType(collectionType));
 
         if (collectionType != ChildNodeListType)
             document().registerNodeList(this);
     }
 
     virtual ~LiveNodeListBase()
     {
         if (type() != ChildNodeListType)
             document().unregisterNodeList(this);
     }
 
-    unsigned length() const;
-    Node* item(unsigned offset) const;
+    ContainerNode& rootNode() const;
+    bool overridesItemAfter() const { return m_overridesItemAfter; }
+    Node* itemBefore(const Node* previousItem) const;
 
     ALWAYS_INLINE bool hasIdNameCache() const { return !isLiveNodeListType(type()); }
     ALWAYS_INLINE bool isRootedAtDocument() const { return m_rootType == NodeListIsRootedAtDocument || m_rootType == NodeListIsRootedAtDocumentIfOwnerHasItemrefAttr; }
     ALWAYS_INLINE NodeListInvalidationType invalidationType() const { return static_cast<NodeListInvalidationType>(m_invalidationType); }
     ALWAYS_INLINE CollectionType type() const { return static_cast<CollectionType>(m_collectionType); }
     ContainerNode* ownerNode() const { return m_ownerNode.get(); }
     ALWAYS_INLINE void invalidateCache(const QualifiedName* attrName) const
     {
         if (!attrName || shouldInvalidateTypeOnAttributeChange(invalidationType(), *attrName))
             invalidateCache();
         else if (hasIdNameCache() && (*attrName == HTMLNames::idAttr || *attrName == HTMLNames::nameAttr))
             invalidateIdNameCacheMaps();
     }
-    virtual void invalidateCache() const;
+    virtual void invalidateCache() const = 0;
 
     static bool shouldInvalidateTypeOnAttributeChange(NodeListInvalidationType, const QualifiedName&);
 
 protected:
     Document& document() const { return m_ownerNode->document(); }
-    ContainerNode& rootNode() const;
-    bool overridesItemAfter() const { return m_overridesItemAfter; }
-
-    ALWAYS_INLINE Node* cachedItem() const { return m_cachedItem; }
-    ALWAYS_INLINE unsigned cachedItemOffset() const { ASSERT(cachedItem()); return m_cachedItemOffset; }
-
-    ALWAYS_INLINE bool isLengthCacheValid() const { return m_isLengthCacheValid; }
-    ALWAYS_INLINE unsigned cachedLength() const { return m_cachedLength; }
-    ALWAYS_INLINE void setLengthCache(unsigned length) const
-    {
-        m_cachedLength = length;
-        m_isLengthCacheValid = true;
-    }
-    ALWAYS_INLINE void setItemCache(Node* item, unsigned offset) const
-    {
-        ASSERT(item);
-        m_cachedItem = item;
-        m_cachedItemOffset = offset;
-    }
 
     ALWAYS_INLINE NodeListRootType rootType() const { return static_cast<NodeListRootType>(m_rootType); }
     bool shouldOnlyIncludeDirectChildren() const { return m_shouldOnlyIncludeDirectChildren; }
 
 private:
-    Node* itemBeforeOrAfterCachedItem(unsigned offset, const ContainerNode& root) const;
-    bool isLastItemCloserThanLastOrCachedItem(unsigned offset) const;
-    bool isFirstItemCloserThanCachedItem(unsigned offset) const;
     Node* iterateForPreviousNode(Node* current) const;
-    Node* itemBefore(const Node* previousItem) const;
     void invalidateIdNameCacheMaps() const;
 
     RefPtr<ContainerNode> m_ownerNode; // Cannot be null.
-    mutable Node* m_cachedItem;
-    mutable unsigned m_cachedLength;
-    mutable unsigned m_cachedItemOffset;
-    mutable unsigned m_isLengthCacheValid : 1;
     const unsigned m_rootType : 2;
     const unsigned m_invalidationType : 4;
     const unsigned m_shouldOnlyIncludeDirectChildren : 1;
     const unsigned m_collectionType : 5;
 
     // From HTMLCollection
     const unsigned m_overridesItemAfter : 1;
 };
 
 ALWAYS_INLINE bool LiveNodeListBase::shouldInvalidateTypeOnAttributeChange(NodeListInvalidationType type, const QualifiedName& attrName)
@@ skipping 21 matching lines @@
     return false;
 }
 
 class LiveNodeList : public NodeList, public LiveNodeListBase {
 public:
     LiveNodeList(PassRefPtr<ContainerNode> ownerNode, CollectionType collectionType, NodeListInvalidationType invalidationType, NodeListRootType rootType = NodeListIsRootedAtNode)
         : LiveNodeListBase(ownerNode.get(), rootType, invalidationType, collectionType == ChildNodeListType,
         collectionType, DoesNotOverrideItemAfter)
     { }
 
-    virtual unsigned length() const OVERRIDE FINAL { return LiveNodeListBase::length(); }
-    virtual Node* item(unsigned offset) const OVERRIDE FINAL { return LiveNodeListBase::item(offset); }
+    virtual unsigned length() const OVERRIDE FINAL { return m_collectionIndexCache.nodeCount(*this); }
+    virtual Node* item(unsigned offset) const OVERRIDE FINAL { return m_collectionIndexCache.nodeAt(*this, offset); }
     virtual Node* namedItem(const AtomicString&) const OVERRIDE FINAL;
     virtual bool nodeMatches(const Element&) const = 0;
     // Avoid ambiguity since both NodeList and LiveNodeListBase have an ownerNode() method.
     using LiveNodeListBase::ownerNode;
 
+    virtual void invalidateCache() const OVERRIDE FINAL;
+
+    // Collection IndexCache API.
     Node* traverseToFirstElement(const ContainerNode& root) const;
     Node* traverseForwardToOffset(unsigned offset, Node& currentNode, unsigned& currentOffset, const ContainerNode& root) const;
 
 private:
     virtual bool isLiveNodeList() const OVERRIDE FINAL { return true; }
+
+    mutable CollectionIndexCache<LiveNodeList> m_collectionIndexCache;
 };
 
 } // namespace WebCore
 
 #endif // LiveNodeList_h