Implement style invalidation tree walk for targeted style recalc upon class change.

Source/core/css/RuleFeature.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 11 matching lines @@
 #ifndef RuleFeature_h
 #define RuleFeature_h
 
 #include "core/css/analyzer/DescendantInvalidationSet.h"
 #include "wtf/Forward.h"
 #include "wtf/HashSet.h"
 #include "wtf/text/AtomicStringHash.h"
 
 namespace WebCore {
 
+class Document;
+class ShadowRoot;
 class StyleRule;
 class CSSSelector;
 class CSSSelectorList;
 class RuleData;
+class SpaceSplitString;
 
 struct RuleFeature {
     RuleFeature(StyleRule* rule, unsigned selectorIndex, bool hasDocumentSecurityOrigin)
         : rule(rule)
         , selectorIndex(selectorIndex)
         , hasDocumentSecurityOrigin(hasDocumentSecurityOrigin)
     {
     }
     StyleRule* rule;
     unsigned selectorIndex;
     bool hasDocumentSecurityOrigin;
 };
 
 class RuleFeatureSet {
 public:
-    RuleFeatureSet() { }
+    RuleFeatureSet();
 
     void add(const RuleFeatureSet&);
     void clear();
 
     void collectFeaturesFromSelector(const CSSSelector&);
     void collectFeaturesFromRuleData(const RuleData&);
 
     bool usesSiblingRules() const { return !siblingRules.isEmpty(); }
     bool usesFirstLineRules() const { return m_metadata.usesFirstLineRules; }
 
@@ skipping 10 matching lines @@
     {
         ASSERT(!classValue.isEmpty());
         return m_metadata.classesInRules.contains(classValue);
     }
 
     inline bool hasSelectorForId(const AtomicString& idValue) const
     {
         return m_metadata.idsInRules.contains(idValue);
     }
 
+    // If a class changed on the element, this method should be called in order to schedule style recalc.

[ojan, 2014/01/30 19:08:39]

We generally don't put "what" comments like this. It's clear from the method
name that this is what it does.

[chrishtr, 2014/01/30 19:25:48]

Done.

+    void scheduleStyleInvalidationForClassChange(const SpaceSplitString& changedClasses, Element*);
+    void scheduleStyleInvalidationForClassChange(const SpaceSplitString& oldClasses, const SpaceSplitString& newClasses, Element*);
+
+    // Computes which elements in the document need style recalculation.

[ojan, 2014/01/30 19:08:39]

Ditto. This comment doesn't really tell me anything. To understand what this
function does, I still need to look at the code.

[chrishtr, 2014/01/30 19:25:48]

Done.

+    void computeStyleInvalidation(Document&);
+
     int hasIdsInSelectors() const
     {
         return m_metadata.idsInRules.size() > 0;
     }
 
     // Marks the given attribute name as "appearing in a selector". Used for
     // CSS properties such as content: ... attr(...) ...
     void addAttributeInASelector(const AtomicString& attributeName);
 
     Vector<RuleFeature> siblingRules;
     Vector<RuleFeature> uncommonAttributeRules;
 
 private:
     typedef HashMap<AtomicString, RefPtr<DescendantInvalidationSet> > InvalidationSetMap;
+    typedef Vector<DescendantInvalidationSet*> InvalidationList;
+    typedef HashMap<Element*, InvalidationList*> PendingInvalidationMap;
     struct FeatureMetadata {
         FeatureMetadata()
             : usesFirstLineRules(false)
             , foundSiblingSelector(false)
             , maxDirectAdjacentSelectors(0)
         { }
         void add(const FeatureMetadata& other);
         void clear();
 
         bool usesFirstLineRules;
         bool foundSiblingSelector;
         unsigned maxDirectAdjacentSelectors;
         HashSet<AtomicString> idsInRules;
         HashSet<AtomicString> classesInRules;
         HashSet<AtomicString> attrsInRules;
     };
 
+    // These return true if setNeedsStyleRecalc() should be run on the Element, as a fallback.
+    bool computeInvalidationSetsForClassChange(const SpaceSplitString& changedClasses, Element*);
+    bool computeInvalidationSetsForClassChange(const SpaceSplitString& oldClasses, const SpaceSplitString& newClasses, Element*);
+
     void collectFeaturesFromSelector(const CSSSelector&, FeatureMetadata&);
     void collectFeaturesFromSelectorList(const CSSSelectorList*, FeatureMetadata&);
+
     DescendantInvalidationSet& ensureClassInvalidationSet(const AtomicString& className);
     bool updateClassInvalidationSets(const CSSSelector&);
 
+    void addClassToInvalidationSet(const AtomicString& className, Element*);
+
+    bool invalidateStyleForClassChange(Element*, Vector<AtomicString>&, bool foundInvalidationSet);
+    bool invalidateStyleForClassChangeOnChildren(Element*, Vector<AtomicString>& invalidationClasses, bool foundInvalidationSet);
+
+    InvalidationList& ensurePendingInvalidationList(Element*);
+
+    FeatureMetadata m_metadata;
     InvalidationSetMap m_classInvalidationSets;
-    FeatureMetadata m_metadata;
+    PendingInvalidationMap m_pendingInvalidationMap;
+
+    bool m_targetedStyleRecalcEnabled;
 };
 
 } // namespace WebCore
 
 #endif // RuleFeature_h