third_party/WebKit/Source/core/dom/ElementDataCache.cpp

   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/ElementDataCache.h"
  29
  30 #include "core/dom/ElementData.h"
  31
  32 namespace blink {
  33
  34 DEFINE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(ElementDataCache)
  35
  36 inline unsigned attributeHash(const Vector<Attribute>& attributes)
  37 {
  38     return StringHasher::hashMemory(attributes.data(), attributes.size() * sizeof(Attribute));
  39 }
  40
  41 inline bool hasSameAttributes(const Vector<Attribute>& attributes, ShareableElementData& elementData)
  42 {
  43     if (attributes.size() != elementData.attributes().size())
  44         return false;
  45     return !memcmp(attributes.data(), elementData.m_attributeArray, attributes.size() * sizeof(Attribute));
  46 }
  47
  48 PassRefPtrWillBeRawPtr<ShareableElementData> ElementDataCache::cachedShareableElementDataWithAttributes(const Vector<Attribute>& attributes)
  49 {
  50     ASSERT(!attributes.isEmpty());
  51
  52     ShareableElementDataCache::ValueType* it = m_shareableElementDataCache.add(attributeHash(attributes), nullptr).storedValue;
  53
  54     // FIXME: This prevents sharing when there's a hash collision.
  55     if (it->value && !hasSameAttributes(attributes, *it->value))
  56         return ShareableElementData::createWithAttributes(attributes);
  57
  58     if (!it->value)
  59         it->value = ShareableElementData::createWithAttributes(attributes);
  60
  61     return it->value.get();
  62 }
  63
  64 ElementDataCache::ElementDataCache()
  65 {
  66 }
  67
  68 DEFINE_TRACE(ElementDataCache)
  69 {
  70 #if ENABLE(OILPAN)
  71     visitor->trace(m_shareableElementDataCache);
  72 #endif
  73 }
  74
  75 }