Merge 143840

Source/WebCore/dom/TreeScope.h

 /*
  * Copyright (C) 2011 Google Inc. All Rights Reserved.
  * Copyright (C) 2012 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 74 matching lines @@
     // Anchor name matching is case sensitive in strict mode and not case sensitive in
     // quirks mode for historical compatibility reasons.
     Element* findAnchor(const String& name);
 
     virtual bool applyAuthorStyles() const;
     virtual bool resetStyleInheritance() const;
 
     // Used by the basic DOM mutation methods (e.g., appendChild()).
     void adoptIfNeeded(Node*);
 
-    ContainerNode* rootNode() const { return m_rootNode; }
+    Node* rootNode() const { return m_rootNode; }
 
     IdTargetObserverRegistry& idTargetObserverRegistry() const { return *m_idTargetObserverRegistry.get(); }
 
     virtual void reportMemoryUsage(MemoryObjectInfo*) const;
 
     static TreeScope* noDocumentInstance()
     {
         DEFINE_STATIC_LOCAL(TreeScope, instance, ());
         return &instance;
     }
 
+    // Nodes belonging to this scope hold guard references -
+    // these are enough to keep the scope from being destroyed, but
+    // not enough to keep it from removing its children. This allows a
+    // node that outlives its scope to still have a valid document
+    // pointer without introducing reference cycles.
+    void guardRef()
+    {
+        ASSERT(!deletionHasBegun());
+        ++m_guardRefCount;
+    }
+
+    void guardDeref()
+    {
+        ASSERT(!deletionHasBegun());
+        --m_guardRefCount;
+        if (!m_guardRefCount && !refCount() && this != noDocumentInstance()) {
+            beginDeletion();
+            delete this;
+        }
+    }
+
+    void removedLastRefToScope();
+
 protected:
     TreeScope(ContainerNode*, Document*);
     TreeScope(Document*);
     virtual ~TreeScope();
 
     void destroyTreeScopeData();
     void clearDocumentScope();
     void setDocumentScope(Document* document)
     {
         ASSERT(document);
         ASSERT(this != noDocumentInstance());
         m_documentScope = document;
     }
 
+    bool hasGuardRefCount() const { return m_guardRefCount; }
+
 private:
     TreeScope();
 
-    ContainerNode* m_rootNode;
+    virtual void dispose() { }
+
+    int refCount() const;
+#ifndef NDEBUG
+    bool deletionHasBegun();
+    void beginDeletion();
+#else
+    bool deletionHasBegun() { return false; }
+    void beginDeletion() { }
+#endif
+
+    Node* m_rootNode;
     Document* m_documentScope;
     TreeScope* m_parentTreeScope;
+    int m_guardRefCount;
 
     OwnPtr<DocumentOrderedMap> m_elementsById;
     OwnPtr<DocumentOrderedMap> m_imageMapsByName;
     OwnPtr<DocumentOrderedMap> m_labelsByForAttribute;
 
     OwnPtr<IdTargetObserverRegistry> m_idTargetObserverRegistry;
 
     mutable RefPtr<DOMSelection> m_selection;
 };
 
 inline bool TreeScope::hasElementWithId(AtomicStringImpl* id) const
 {
     ASSERT(id);
     return m_elementsById && m_elementsById->contains(id);
 }
 
 inline bool TreeScope::containsMultipleElementsWithId(const AtomicString& id) const
 {
     return m_elementsById && m_elementsById->containsMultiple(id.impl());
 }
 
 Node* nodeFromPoint(Document*, int x, int y, LayoutPoint* localPoint = 0);
 TreeScope* commonTreeScope(Node*, Node*);
 
 } // namespace WebCore
 
 #endif // TreeScope_h