Add a first pass of a class descendant invalidator, and a containing RuleSetAnalyzer

Source/core/css/analyzer/DescendantInvalidationSet.h

Index: Source/core/css/analyzer/DescendantInvalidationSet.h
diff --git a/Source/core/rendering/style/StyleVariableData.h b/Source/core/css/analyzer/DescendantInvalidationSet.h
similarity index 55%
copy from Source/core/rendering/style/StyleVariableData.h
copy to Source/core/css/analyzer/DescendantInvalidationSet.h
index 23429f19c2e3058532656a3c0e130e97a09339af..85f22dec9d1a9dc1df1bf3189c65c16564fbc4ba 100644
--- a/Source/core/rendering/style/StyleVariableData.h
+++ b/Source/core/css/analyzer/DescendantInvalidationSet.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012 Google Inc.  All rights reserved.
+ * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
@@ -28,37 +28,51 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-
-#ifndef StyleVariableData_h
-#define StyleVariableData_h
+#ifndef DescendantInvalidationSet_h
+#define DescendantInvalidationSet_h
 
 #include "wtf/Forward.h"
-#include "wtf/HashMap.h"
+#include "wtf/HashSet.h"
 #include "wtf/RefCounted.h"
+#include "wtf/RefPtr.h"
 #include "wtf/text/AtomicStringHash.h"
 
 namespace WebCore {
 
-class CursorList;
-class QuotesData;
-class ShadowData;
+class Element;
 
-class StyleVariableData : public RefCounted<StyleVariableData> {
+// Tracks data to determine which elements of a DOM subtree need to have style
+// recalculated.
+class DescendantInvalidationSet : public RefCounted<DescendantInvalidationSet> {
 public:
-    static PassRefPtr<StyleVariableData> create() { return adoptRef(new StyleVariableData()); }
-    PassRefPtr<StyleVariableData> copy() const { return adoptRef(new StyleVariableData(*this)); }
+    static PassRefPtr<DescendantInvalidationSet> create()
+    {
+        return adoptRef(new DescendantInvalidationSet);
+    }
+
+    void combine(const DescendantInvalidationSet& other);
 
-    bool operator==(const StyleVariableData& other) const { return other.m_data == m_data; }
-    bool operator!=(const StyleVariableData& other) const { return !(*this == other); }
+    void addClass(const AtomicString& className);
+    void addId(const AtomicString& id);
+    void addTagName(const AtomicString& tagName);
 
-    void setVariable(const AtomicString& name, const String& value) { m_data.set(name, value); }
+    void appendClasses(Vector<AtomicString>& classes);
 
-    HashMap<AtomicString, String> m_data;
+    void setWholeSubtreeInvalid() { m_allDescendantsMightBeInvalid = true; };
+    bool wholeSubtreeInvalid() { return m_allDescendantsMightBeInvalid; }
 private:
-    explicit StyleVariableData() : RefCounted<StyleVariableData>() { }
-    StyleVariableData(const StyleVariableData& other) : RefCounted<StyleVariableData>(), m_data(HashMap<AtomicString, String>(other.m_data)) { }
+    DescendantInvalidationSet();
+
+    bool invalidateElementSubtreeInternal(Element*);
+    // If true, all descendants might be invalidated, so a full subtree recalc is required.
+    bool m_allDescendantsMightBeInvalid;
+
+    // FIXME: optimize this if it becomes a memory issue.
+    HashSet<AtomicString> m_classes;
+    HashSet<AtomicString> m_ids;
+    HashSet<AtomicString> m_tagNames;
 };
 
 } // namespace WebCore
 
-#endif /* StyleVariableData_h */
+#endif // DescendantInvalidationSet_h