1/*
2 * Copyright (C) 2012,2013 Google Inc. All rights reserved.
3 * Copyright (C) 2014 Apple Inc. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met:
8 *
9 *     * Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *     * Redistributions in binary form must reproduce the above
12 * copyright notice, this list of conditions and the following disclaimer
13 * in the documentation and/or other materials provided with the
14 * distribution.
15 *     * Neither the name of Google Inc. nor the names of its
16 * contributors may be used to endorse or promote products derived from
17 * this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#ifndef CollectionItemsCache_h
33#define CollectionItemsCache_h
34
35#include "core/html/CollectionIndexCache.h"
36#include "wtf/Vector.h"
37#include <v8.h>
38
39namespace blink {
40
41template <typename Collection, typename NodeType>
42class CollectionItemsCache : public CollectionIndexCache<Collection, NodeType> {
43    typedef CollectionIndexCache<Collection, NodeType> Base;
44
45public:
46    CollectionItemsCache();
47    ~CollectionItemsCache();
48
49    unsigned nodeCount(const Collection&);
50    NodeType* nodeAt(const Collection&, unsigned index);
51    void invalidate();
52
53private:
54    ptrdiff_t allocationSize() const { return m_cachedList.capacity() * sizeof(NodeType*); }
55    static void reportExtraMemoryCostForCollectionItemsCache(ptrdiff_t diff)
56    {
57        v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(diff);
58    }
59
60    bool m_listValid;
61    Vector<NodeType*> m_cachedList;
62};
63
64template <typename Collection, typename NodeType>
65CollectionItemsCache<Collection, NodeType>::CollectionItemsCache()
66    : m_listValid(false)
67{
68}
69
70template <typename Collection, typename NodeType>
71CollectionItemsCache<Collection, NodeType>::~CollectionItemsCache()
72{
73    if (ptrdiff_t diff = allocationSize())
74        reportExtraMemoryCostForCollectionItemsCache(-diff);
75}
76
77template <typename Collection, typename NodeType>
78void CollectionItemsCache<Collection, NodeType>::invalidate()
79{
80    Base::invalidate();
81    if (m_listValid) {
82        m_cachedList.shrink(0);
83        m_listValid = false;
84    }
85}
86
87template <class Collection, class NodeType>
88unsigned CollectionItemsCache<Collection, NodeType>::nodeCount(const Collection& collection)
89{
90    if (this->isCachedNodeCountValid())
91        return this->cachedNodeCount();
92
93    NodeType* currentNode = collection.traverseToFirst();
94    unsigned currentIndex = 0;
95    ptrdiff_t oldCapacity = allocationSize();
96    while (currentNode) {
97        m_cachedList.append(currentNode);
98        currentNode = collection.traverseForwardToOffset(currentIndex + 1, *currentNode, currentIndex);
99    }
100    if (ptrdiff_t diff = allocationSize() - oldCapacity)
101        reportExtraMemoryCostForCollectionItemsCache(diff);
102
103    this->setCachedNodeCount(m_cachedList.size());
104    m_listValid = true;
105    return this->cachedNodeCount();
106}
107
108template <typename Collection, typename NodeType>
109inline NodeType* CollectionItemsCache<Collection, NodeType>::nodeAt(const Collection& collection, unsigned index)
110{
111    if (m_listValid) {
112        ASSERT(this->isCachedNodeCountValid());
113        return index < this->cachedNodeCount() ? m_cachedList[index] : 0;
114    }
115    return Base::nodeAt(collection, index);
116}
117
118} // namespace blink
119
120#endif // CollectionItemsCache_h
121