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      1 /*
      2  * Copyright (C) 2012, 2013 Apple Inc. All Rights Reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  *
     25  */
     26 
     27 #include "config.h"
     28 #include "core/dom/DocumentSharedObjectPool.h"
     29 
     30 #include "core/dom/Element.h"
     31 
     32 namespace WebCore {
     33 
     34 class ShareableElementDataCacheKey {
     35 public:
     36     ShareableElementDataCacheKey(const Attribute* attributes, unsigned attributeCount)
     37         : m_attributes(attributes)
     38         , m_attributeCount(attributeCount)
     39     { }
     40 
     41     bool operator!=(const ShareableElementDataCacheKey& other) const
     42     {
     43         if (m_attributeCount != other.m_attributeCount)
     44             return true;
     45         return memcmp(m_attributes, other.m_attributes, sizeof(Attribute) * m_attributeCount);
     46     }
     47 
     48     unsigned hash() const
     49     {
     50         return StringHasher::hashMemory(m_attributes, m_attributeCount * sizeof(Attribute));
     51     }
     52 
     53 private:
     54     const Attribute* m_attributes;
     55     unsigned m_attributeCount;
     56 };
     57 
     58 class ShareableElementDataCacheEntry {
     59 public:
     60     ShareableElementDataCacheEntry(const ShareableElementDataCacheKey& k, PassRefPtr<ShareableElementData> v)
     61         : key(k)
     62         , value(v)
     63     { }
     64 
     65     ShareableElementDataCacheKey key;
     66     RefPtr<ShareableElementData> value;
     67 };
     68 
     69 PassRefPtr<ShareableElementData> DocumentSharedObjectPool::cachedShareableElementDataWithAttributes(const Vector<Attribute>& attributes)
     70 {
     71     ASSERT(!attributes.isEmpty());
     72 
     73     ShareableElementDataCacheKey cacheKey(attributes.data(), attributes.size());
     74     unsigned cacheHash = cacheKey.hash();
     75 
     76     ShareableElementDataCache::iterator cacheIterator = m_shareableElementDataCache.add(cacheHash, nullptr).iterator;
     77     if (cacheIterator->value && cacheIterator->value->key != cacheKey)
     78         cacheHash = 0;
     79 
     80     RefPtr<ShareableElementData> elementData;
     81     if (cacheHash && cacheIterator->value)
     82         elementData = cacheIterator->value->value;
     83     else
     84         elementData = ShareableElementData::createWithAttributes(attributes);
     85 
     86     if (!cacheHash || cacheIterator->value)
     87         return elementData.release();
     88 
     89     cacheIterator->value = adoptPtr(new ShareableElementDataCacheEntry(ShareableElementDataCacheKey(elementData->m_attributeArray, elementData->length()), elementData));
     90 
     91     return elementData.release();
     92 }
     93 
     94 DocumentSharedObjectPool::DocumentSharedObjectPool()
     95 {
     96 }
     97 
     98 DocumentSharedObjectPool::~DocumentSharedObjectPool()
     99 {
    100 }
    101 
    102 }
    103