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

/*
 * Copyright (C) 2008, 2010 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.
 *
 */

#ifndef NodeListsNodeData_h
#define NodeListsNodeData_h

#include "core/dom/ChildNodeList.h"
#include "core/dom/EmptyNodeList.h"
#include "core/dom/QualifiedName.h"
#include "core/dom/TagCollection.h"
#include "core/html/CollectionType.h"
#include "platform/heap/Handle.h"
#include "wtf/text/AtomicString.h"
#include "wtf/text/StringHash.h"

namespace blink {

class NodeListsNodeData final : public GarbageCollected<NodeListsNodeData> {
    WTF_MAKE_NONCOPYABLE(NodeListsNodeData);
public:
    ChildNodeList* childNodeList(ContainerNode& node)
    {
        ASSERT_UNUSED(node, !m_childNodeList || node == m_childNodeList->virtualOwnerNode());
        return toChildNodeList(m_childNodeList);
    }

    ChildNodeList* ensureChildNodeList(ContainerNode& node)
    {
        if (m_childNodeList)
            return toChildNodeList(m_childNodeList);
        ChildNodeList* list = ChildNodeList::create(node);
        m_childNodeList = list;
        return list;
    }

    EmptyNodeList* ensureEmptyChildNodeList(Node& node)
    {
        if (m_childNodeList)
            return toEmptyNodeList(m_childNodeList);
        EmptyNodeList* list = EmptyNodeList::create(node);
        m_childNodeList = list;
        return list;
    }

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

    // Oilpan: keep a weak reference to the collection objects.
    // Object unregistration is handled by GC's weak processing.
    typedef HeapHashMap<std::pair<unsigned char, StringImpl*>, WeakMember<LiveNodeListBase>, NodeListAtomicCacheMapEntryHash> NodeListAtomicNameCacheMap;
    typedef HeapHashMap<QualifiedName, WeakMember<TagCollection>> TagCollectionCacheNS;

    template<typename T>
    T* addCache(ContainerNode& node, CollectionType collectionType, const AtomicString& name)
    {
        NodeListAtomicNameCacheMap::AddResult result = m_atomicNameCaches.add(namedNodeListKey(collectionType, name), nullptr);
        if (!result.isNewEntry) {
            return static_cast<T*>(result.storedValue->value.get());
        }

        T* list = T::create(node, collectionType, name);
        result.storedValue->value = list;
        return list;
    }

    template<typename T>
    T* addCache(ContainerNode& node, CollectionType collectionType)
    {
        NodeListAtomicNameCacheMap::AddResult result = m_atomicNameCaches.add(namedNodeListKey(collectionType, starAtom), nullptr);
        if (!result.isNewEntry) {
            return static_cast<T*>(result.storedValue->value.get());
        }

        T* list = T::create(node, collectionType);
        result.storedValue->value = list;
        return list;
    }

    template<typename T>
    T* cached(CollectionType collectionType)
    {
        return static_cast<T*>(m_atomicNameCaches.get(namedNodeListKey(collectionType, starAtom)));
    }

    TagCollection* addCache(ContainerNode& node, const AtomicString& namespaceURI, const AtomicString& localName)
    {
        QualifiedName name(nullAtom, localName, namespaceURI);
        TagCollectionCacheNS::AddResult result = m_tagCollectionCacheNS.add(name, nullptr);
        if (!result.isNewEntry)
            return result.storedValue->value;

        TagCollection* list = TagCollection::create(node, namespaceURI, localName);
        result.storedValue->value = list;
        return list;
    }

    static NodeListsNodeData* create()
    {
        return new NodeListsNodeData;
    }

    void invalidateCaches(const QualifiedName* attrName = 0);

    bool isEmpty() const
    {
        return !m_childNodeList && m_atomicNameCaches.isEmpty() && m_tagCollectionCacheNS.isEmpty();
    }

    void adoptTreeScope()
    {
        invalidateCaches();
    }

    void adoptDocument(Document& oldDocument, Document& newDocument)
    {
        DCHECK_NE(oldDocument, newDocument);

        NodeListAtomicNameCacheMap::const_iterator atomicNameCacheEnd = m_atomicNameCaches.end();
        for (NodeListAtomicNameCacheMap::const_iterator it = m_atomicNameCaches.begin(); it != atomicNameCacheEnd; ++it) {
            LiveNodeListBase* list = it->value;
            list->didMoveToDocument(oldDocument, newDocument);
        }

        TagCollectionCacheNS::const_iterator tagEnd = m_tagCollectionCacheNS.end();
        for (TagCollectionCacheNS::const_iterator it = m_tagCollectionCacheNS.begin(); it != tagEnd; ++it) {
            LiveNodeListBase* list = it->value;
            DCHECK(!list->isRootedAtTreeScope());
            list->didMoveToDocument(oldDocument, newDocument);
        }
    }

    DECLARE_TRACE();

    DECLARE_TRACE_WRAPPERS();

private:
    NodeListsNodeData()
        : m_childNodeList(nullptr)
    { }

    std::pair<unsigned char, StringImpl*> namedNodeListKey(CollectionType type, const AtomicString& name)
    {
        // Holding the raw StringImpl is safe because |name| is retained by the NodeList and the NodeList
        // is reponsible for removing itself from the cache on deletion.
        return std::pair<unsigned char, StringImpl*>(type, name.impl());
    }

    // Can be a ChildNodeList or an EmptyNodeList.
    WeakMember<NodeList> m_childNodeList;
    NodeListAtomicNameCacheMap m_atomicNameCaches;
    TagCollectionCacheNS m_tagCollectionCacheNS;
};

template <typename Collection>
inline Collection* ContainerNode::ensureCachedCollection(CollectionType type)
{
    return ensureNodeLists().addCache<Collection>(*this, type);
}

template <typename Collection>
inline Collection* ContainerNode::ensureCachedCollection(CollectionType type, const AtomicString& name)
{
    return ensureNodeLists().addCache<Collection>(*this, type, name);
}

template <typename Collection>
inline Collection* ContainerNode::ensureCachedCollection(CollectionType type, const AtomicString& namespaceURI, const AtomicString& localName)
{
    ASSERT_UNUSED(type, type == TagCollectionType);
    return ensureNodeLists().addCache(*this, namespaceURI, localName);
}

template <typename Collection>
inline Collection* ContainerNode::cachedCollection(CollectionType type)
{
    NodeListsNodeData* nodeLists = this->nodeLists();
    return nodeLists ? nodeLists->cached<Collection>(type) : 0;
}

} // namespace blink

#endif // NodeListsNodeData_h