Make nodes supports weak references. b=360291 r/sr=jst

content/base/public/nsINode.h

@@ -112,6 +112,8 @@ public:
 class nsINode : public nsINode_base {
 public:
   friend class nsNodeUtils;
+  friend class nsNodeWeakReference;
+  friend class nsNodeSupportsWeakRefTearoff;
 
 #ifdef MOZILLA_INTERNAL_API
   nsINode(nsINodeInfo* aNodeInfo)
@@ -551,7 +553,8 @@ public:
   public:
     nsSlots(PtrBits aFlags)
       : mFlags(aFlags),
-        mChildNodes(nsnull)
+        mChildNodes(nsnull),
+        mWeakReference(nsnull)
     {
     }
 
@@ -579,6 +582,11 @@ public:
      * MSVC 7 doesn't like this as an nsRefPtr
      */
     nsChildContentList* mChildNodes;
+
+    /**
+     * Weak reference to this node
+     */
+    nsNodeWeakReference* mWeakReference;
   };
 
 #ifdef DEBUG

content/base/src/nsDOMAttribute.cpp

@@ -81,6 +81,8 @@ NS_INTERFACE_MAP_BEGIN(nsDOMAttribute)
   NS_INTERFACE_MAP_ENTRY(nsIDOMNode)
   NS_INTERFACE_MAP_ENTRY(nsIDOM3Node)
   NS_INTERFACE_MAP_ENTRY(nsIDOM3Attr)
+  NS_INTERFACE_MAP_ENTRY_TEAROFF(nsISupportsWeakReference,
+                                 new nsNodeSupportsWeakRefTearoff(this))
   NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIDOMAttr)
   NS_INTERFACE_MAP_ENTRY_CONTENT_CLASSINFO(Attr)
 NS_INTERFACE_MAP_END

content/base/src/nsGenericDOMDataNode.cpp

@@ -93,6 +93,8 @@ NS_INTERFACE_MAP_BEGIN(nsGenericDOMDataNode)
                                  nsDOMEventRTTearoff::Create(this))
   NS_INTERFACE_MAP_ENTRY_TEAROFF(nsIDOMNSEventTarget,
                                  nsDOMEventRTTearoff::Create(this))
+  NS_INTERFACE_MAP_ENTRY_TEAROFF(nsISupportsWeakReference,
+                                 new nsNodeSupportsWeakRefTearoff(this))
   NS_INTERFACE_MAP_ENTRY_TEAROFF(nsIDOM3Node, new nsNode3Tearoff(this))
   NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIContent)
 NS_INTERFACE_MAP_END

content/base/src/nsGenericElement.cpp

@@ -144,6 +144,10 @@ nsINode::nsSlots::~nsSlots()
     mChildNodes->DropReference();
     NS_RELEASE(mChildNodes);
   }
+
+  if (mWeakReference) {
+    mWeakReference->NoticeNodeDestruction();
+  }
 }
 
 //----------------------------------------------------------------------
@@ -609,6 +613,54 @@ nsNode3Tearoff::IsDefaultNamespace(const nsAString& aNamespaceURI,
   return NS_OK;
 }
 
+//----------------------------------------------------------------------
+
+NS_IMPL_ISUPPORTS1(nsNodeWeakReference,
+                   nsIWeakReference)
+
+nsNodeWeakReference::~nsNodeWeakReference()
+{
+  if (mNode) {
+    NS_ASSERTION(mNode->GetSlots() &&
+                 mNode->GetSlots()->mWeakReference == this,
+                 "Weak reference has wrong value");
+    mNode->GetSlots()->mWeakReference = nsnull;
+  }
+}
+
+NS_IMETHODIMP
+nsNodeWeakReference::QueryReferent(const nsIID& aIID, void** aInstancePtr)
+{
+  return mNode ? mNode->QueryInterface(aIID, aInstancePtr) :
+                 NS_ERROR_NULL_POINTER;
+}
+
+
+NS_INTERFACE_MAP_BEGIN(nsNodeSupportsWeakRefTearoff)
+  NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
+NS_INTERFACE_MAP_END_AGGREGATED(mNode)
+
+NS_IMPL_ADDREF(nsNodeSupportsWeakRefTearoff)
+NS_IMPL_RELEASE(nsNodeSupportsWeakRefTearoff)
+
+NS_IMETHODIMP
+nsNodeSupportsWeakRefTearoff::GetWeakReference(nsIWeakReference** aInstancePtr)
+{
+  nsINode::nsSlots* slots = mNode->GetSlots();
+  NS_ENSURE_TRUE(slots, NS_ERROR_OUT_OF_MEMORY);
+
+  if (!slots->mWeakReference) {
+    slots->mWeakReference = new nsNodeWeakReference(mNode);
+    NS_ENSURE_TRUE(slots->mWeakReference, NS_ERROR_OUT_OF_MEMORY);
+  }
+
+  NS_ADDREF(*aInstancePtr = slots->mWeakReference);
+
+  return NS_OK;
+}
+
+//----------------------------------------------------------------------
+
 nsDOMEventRTTearoff *
 nsDOMEventRTTearoff::mCachedEventTearoff[NS_EVENT_TEAROFF_CACHE_SIZE];
 
@@ -2963,6 +3015,8 @@ NS_INTERFACE_MAP_BEGIN(nsGenericElement)
                                  nsDOMEventRTTearoff::Create(this))
   NS_INTERFACE_MAP_ENTRY_TEAROFF(nsIDOMNSEventTarget,
                                  nsDOMEventRTTearoff::Create(this))
+  NS_INTERFACE_MAP_ENTRY_TEAROFF(nsISupportsWeakReference,
+                                 new nsNodeSupportsWeakRefTearoff(this))
   NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIContent)
 NS_INTERFACE_MAP_END
 

content/base/src/nsGenericElement.h

@@ -60,6 +60,7 @@
 #include "nsAttrAndChildArray.h"
 #include "mozFlushType.h"
 #include "nsDOMAttributeMap.h"
+#include "nsIWeakReference.h"
 
 class nsIDOMAttr;
 class nsIDOMEventListener;
@@ -107,7 +108,7 @@ private:
 };
 
 /**
- * A tearoff class for nsGenericElement to implement the nsIDOM3Node functions
+ * A tearoff class for nsGenericElement to implement additional interfaces
  */
 class nsNode3Tearoff : public nsIDOM3Node
 {
@@ -138,6 +139,55 @@ private:
   nsCOMPtr<nsIContent> mContent;
 };
 
+/**
+ * A class that implements nsIWeakReference
+ */
+
+class nsNodeWeakReference : public nsIWeakReference
+{
+public:
+  nsNodeWeakReference(nsINode* aNode)
+    : mNode(aNode)
+  {
+  }
+
+  ~nsNodeWeakReference();
+
+  // nsISupports
+  NS_DECL_ISUPPORTS
+
+  // nsIWeakReference
+  NS_DECL_NSIWEAKREFERENCE
+
+  void NoticeNodeDestruction()
+  {
+    mNode = nsnull;
+  }
+
+private:
+  nsINode* mNode;
+};
+
+/**
+ * Tearoff to use for nodes to implement nsISupportsWeakReference
+ */
+class nsNodeSupportsWeakRefTearoff : public nsISupportsWeakReference
+{
+public:
+  nsNodeSupportsWeakRefTearoff(nsINode* aNode)
+    : mNode(aNode)
+  {
+  }
+
+  // nsISupports
+  NS_DECL_ISUPPORTS
+
+  // nsISupportsWeakReference
+  NS_DECL_NSISUPPORTSWEAKREFERENCE
+
+private:
+  nsCOMPtr<nsINode> mNode;
+};
 
 #define NS_EVENT_TEAROFF_CACHE_SIZE 4
 
@@ -905,6 +955,11 @@ public:
       */
       nsIControllers* mControllers; // [OWNER]
     };
+    
+    /**
+     * Weak reference to this node
+     */
+    nsNodeWeakReference* mWeakReference;
   };
 
 protected: