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      1 /*
      2  * Copyright (C) 1999 Lars Knoll (knoll (at) kde.org)
      3  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
      4  * Copyright (C) 2013 Google Inc. All rights reserved.
      5  *
      6  * This library is free software; you can redistribute it and/or
      7  * modify it under the terms of the GNU Library General Public
      8  * License as published by the Free Software Foundation; either
      9  * version 2 of the License, or (at your option) any later version.
     10  *
     11  * This library is distributed in the hope that it will be useful,
     12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     14  * Library General Public License for more details.
     15  *
     16  * You should have received a copy of the GNU Library General Public License
     17  * along with this library; see the file COPYING.LIB.  If not, write to
     18  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     19  * Boston, MA 02110-1301, USA.
     20  *
     21  */
     22 
     23 #ifndef MatchedPropertiesCache_h
     24 #define MatchedPropertiesCache_h
     25 
     26 #include "core/css/resolver/MatchResult.h"
     27 
     28 #include "platform/Timer.h"
     29 #include "wtf/Forward.h"
     30 #include "wtf/HashMap.h"
     31 #include "wtf/Noncopyable.h"
     32 
     33 namespace WebCore {
     34 
     35 class RenderStyle;
     36 class StyleResolverState;
     37 
     38 struct CachedMatchedProperties {
     39     Vector<MatchedProperties> matchedProperties;
     40     MatchRanges ranges;
     41     RefPtr<RenderStyle> renderStyle;
     42     RefPtr<RenderStyle> parentRenderStyle;
     43 
     44     void set(const RenderStyle*, const RenderStyle* parentStyle, const MatchResult&);
     45     void clear();
     46 };
     47 
     48 class MatchedPropertiesCache {
     49     WTF_MAKE_NONCOPYABLE(MatchedPropertiesCache);
     50 public:
     51     MatchedPropertiesCache();
     52 
     53     const CachedMatchedProperties* find(unsigned hash, const StyleResolverState&, const MatchResult&);
     54     void add(const RenderStyle*, const RenderStyle* parentStyle, unsigned hash, const MatchResult&);
     55 
     56     void clear();
     57     void clearViewportDependent();
     58 
     59     static bool isCacheable(const Element*, const RenderStyle*, const RenderStyle* parentStyle);
     60 
     61 private:
     62     // Every N additions to the matched declaration cache trigger a sweep where entries holding
     63     // the last reference to a style declaration are garbage collected.
     64     void sweep(Timer<MatchedPropertiesCache>*);
     65 
     66     unsigned m_additionsSinceLastSweep;
     67 
     68     typedef HashMap<unsigned, OwnPtr<CachedMatchedProperties> > Cache;
     69     Cache m_cache;
     70 
     71     Timer<MatchedPropertiesCache> m_sweepTimer;
     72 };
     73 
     74 }
     75 
     76 #endif
     77