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1 /*
2  * Copyright (C) 1999 Lars Knoll (knoll@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 
58     static bool isCacheable(const Element*, const RenderStyle*, const RenderStyle* parentStyle);
59 
60 private:
61     // Every N additions to the matched declaration cache trigger a sweep where entries holding
62     // the last reference to a style declaration are garbage collected.
63     void sweep(Timer<MatchedPropertiesCache>*);
64 
65     unsigned m_additionsSinceLastSweep;
66 
67     typedef HashMap<unsigned, OwnPtr<CachedMatchedProperties> > Cache;
68     Cache m_cache;
69 
70     Timer<MatchedPropertiesCache> m_sweepTimer;
71 };
72 
73 }
74 
75 #endif
76