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      1 /*
      2  * Copyright (C) 2013 Google, Inc.
      3  * Copyright (C) 1999 Lars Knoll (knoll (at) kde.org)
      4  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple 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 #ifndef SharedStyleFinder_h
     23 #define SharedStyleFinder_h
     24 
     25 #include "core/css/resolver/ElementResolveContext.h"
     26 #include "core/dom/Element.h"
     27 
     28 namespace blink {
     29 
     30 class Element;
     31 class RenderStyle;
     32 class RuleFeatureSet;
     33 class RuleSet;
     34 class SpaceSplitString;
     35 class StyleResolver;
     36 
     37 class SharedStyleFinder {
     38     STACK_ALLOCATED();
     39 public:
     40     // RuleSets are passed non-const as the act of matching against them can cause them
     41     // to be compacted. :(
     42     SharedStyleFinder(const ElementResolveContext& context,
     43         const RuleFeatureSet& features, RuleSet* siblingRuleSet,
     44         RuleSet* uncommonAttributeRuleSet, StyleResolver& styleResolver)
     45         : m_elementAffectedByClassRules(false)
     46         , m_features(features)
     47         , m_siblingRuleSet(siblingRuleSet)
     48         , m_uncommonAttributeRuleSet(uncommonAttributeRuleSet)
     49         , m_styleResolver(styleResolver)
     50         , m_context(context)
     51     { }
     52 
     53     RenderStyle* findSharedStyle();
     54 
     55 private:
     56     Element* findElementForStyleSharing() const;
     57 
     58     // Only used when we're collecting stats on styles.
     59     bool documentContainsValidCandidate() const;
     60 
     61     bool classNamesAffectedByRules(const SpaceSplitString&) const;
     62 
     63     bool canShareStyleWithElement(Element& candidate) const;
     64     bool canShareStyleWithControl(Element& candidate) const;
     65     bool sharingCandidateHasIdenticalStyleAffectingAttributes(Element& candidate) const;
     66     bool sharingCandidateCanShareHostStyles(Element& candidate) const;
     67     bool sharingCandidateDistributedToSameInsertionPoint(Element& candidate) const;
     68     bool matchesRuleSet(RuleSet*);
     69 
     70     Element& element() const { return *m_context.element(); }
     71     Document& document() const { return element().document(); }
     72 
     73     bool m_elementAffectedByClassRules;
     74     const RuleFeatureSet& m_features;
     75     RawPtrWillBeMember<RuleSet> m_siblingRuleSet;
     76     RawPtrWillBeMember<RuleSet> m_uncommonAttributeRuleSet;
     77     StyleResolver& m_styleResolver;
     78     const ElementResolveContext& m_context;
     79 };
     80 
     81 } // namespace blink
     82 
     83 #endif // SharedStyleFinder_h
     84