First Checked In.

xpcom/base/nsIWeakReference.idl

@@ -0,0 +1,39 @@
+// nsIWeakReference.idl
+
+#include "nsISupports.idl"
+
+[scriptable, uuid(9188bc85-f92e-11d2-81ef-0060083a0bcf)]
+interface nsIWeakReference : nsISupports
+	{
+		void QueryReference( in nsIIDRef uuid, [iid_is(uuid), retval] out nsQIResult result );
+	};
+
+[scriptable, uuid(9188bc86-f92e-11d2-81ef-0060083a0bcf)]
+interface nsISupportsWeakReference : nsISupports
+	{
+		void GetWeakReference( [retval] out nsIWeakReference result );
+	};
+
+%{C++
+
+#ifndef nsCOMPtr_h___
+#include "nsCOMPtr.h"
+#endif
+
+typedef nsCOMPtr<nsIWeakReference> nsWeakPtr;
+
+nsIWeakReference* NS_GetWeakReference( nsISupports* );
+	// ...convenience.  Get a weak reference (if possible) without doing the query yourself
+
+template <class T>
+inline
+nsresult
+CallQueryReference( nsIWeakReference* aSource, T** aDestination )
+	{
+		NS_PRECONDITION(aSource, "null parameter");
+    NS_PRECONDITION(aDestination, "null parameter");
+
+		return aSource->QueryReference(nsCOMTypeInfo<T>::GetIID(), (void**)aDestination);
+	}
+
+%}

xpcom/base/nsWeakReference.cpp

@@ -0,0 +1,83 @@
+// nsWeakReference.cpp
+
+#include "nsWeakReference.h"
+
+nsIWeakReference*
+NS_GetWeakReference( nsISupports* aInstance, nsresult* aResult )
+	{
+		nsIWeakReference* result = 0;
+		nsCOMPtr<nsISupportsWeakReference> factory = do_QueryInterface(aInstance, aResult);
+
+		nsIWeakReference* w
+		if ( factory )
+			result = factory->GetWeakReference();
+		return result;
+	}
+
+nsresult
+nsSupportsWeakReference::GetWeakReference( nsIWeakReference** aInstancePtr )
+	{
+		if ( !aInstancePtr )
+			return NS_ERROR_NULL_POINTER;
+
+		if ( !mProxy )
+			mProxy = new nsWeakReference(this);
+		*aInstancePtr = mProxy;
+
+		nsresult status;
+		if ( !*aInstancePtr )
+			status = NS_NOINTERFACE;
+		else
+			{
+				NS_ADDREF(*aInstancePtr);
+				status = NS_OK;
+			}
+
+		return status;
+	}
+
+nsrefcnt
+nsWeakReference::AddRef()
+	{
+		return ++mRefCount
+	}
+
+nsrefcnt
+nsWeakReference::Release()
+	{
+		nsrefcnt temp = --mRefCount;
+		if ( !mRefCount )
+			delete this;
+		return temp;
+	}
+
+nsresult
+nsWeakReference::QueryInterface( const nsIID& aIID, void** aInstancePtr )
+	{
+		if ( !aInstancePtr )
+			return NS_ERROR_NULL_POINTER;
+
+		if ( aIID.Equals(nsCOMTypeInfo<nsIWeakReference>::GetIID()) )
+			*aInstancePtr = NS_STATIC_CAST(nsIWeakReference*, this);
+		else if ( aIID.Equals(nsCOMTypeInfo<nsISupports>::GetIID()) )
+			*aInstancePtr = NS_STATIC_CAST(nsISupports*, this);
+		else
+			*aInstancePtr = 0;
+
+		nsresult status;
+		if ( !*aInstancePtr )
+			status = NS_NOINTERFACE;
+		else
+			{
+				NS_ADDREF( NS_REINTERPRET_CAST(nsISupports*, *aInstancePtr) );
+				status = NS_OK;
+			}
+
+		return status;
+	}
+
+nsresult
+nsWeakReference::QueryReference( const nsIID& aIID, void** aInstancePtr )
+	{
+		return mReferent ? mReferent->QueryInterface(aIID, aInstancePtr) : NS_ERROR_NULL_PTR;
+	}

xpcom/base/nsWeakReference.h

@@ -0,0 +1,82 @@
+#ifndef nsWeakReference_h__
+#define nsWeakReference_h__
+
+// nsWeakReference.h
+
+#include "nsIWeakReference.h"
+
+class nsSupportsWeakReference : public nsISupportsWeakReference
+	{
+		public:
+			nsSupportsWeakReference()
+					: mProxy(0)
+				{
+					// nothing else to do here
+				}
+
+			inline ~nsSupportsWeakReference();
+
+			virtual nsresult GetWeakReference( nsIWeakReference** );
+
+		private:
+			friend class nsWeakReference;
+
+			void
+			NoticeProxyDestruction()
+					// ...called (only) by an |nsWeakReference| from _its_ dtor.
+				{
+					mProxy = 0;
+				}
+
+			nsWeakReference* mProxy;
+	};
+
+class nsWeakReference : public nsIWeakReference
+	{
+		public:
+		// nsISupports...
+			virtual nsrefcnt AddRef();
+			virtual nsrefcnt Release();
+			virtual nsresult QueryInterface( const nsIID&, void** );
+
+		// nsIWeakReference...
+			virtual nsresult QueryReference( const nsIID&, void** );
+
+
+		private:
+			friend class nsSupportsWeakReference;
+
+			nsWeakReference( nsSupportsWeakReference* referent )
+					: mRefCount(0),
+						mReferent(referent)
+					// ...I can only be constructed by an |nsSupportsWeakReference|
+				{
+					// nothing else to do here
+				}
+
+		 ~nsWeakReference()
+		 			// ...I will only be destroyed by calling |delete| myself.
+				{
+					if ( mReferent )
+						mReferent->NoticeProxyDestruction();
+				}
+
+			void
+			NoticeReferentDestruction()
+					// ...called (only) by an |nsSupportsWeakReference| from _its_ dtor.
+				{
+					mReferent = 0;
+				}
+
+			nsrefcnt									mRefCount;
+			nsSupportsWeakReference*	mReferent;
+	};
+
+inline
+nsSupportsWeakReference::~nsSupportsWeakReference()
+	{
+		if ( mProxy )
+			mProxy->NoticeReferentDestruction();
+	}
+
+#endif

xpcom/glue/nsWeakReference.cpp

@@ -0,0 +1,83 @@
+// nsWeakReference.cpp
+
+#include "nsWeakReference.h"
+
+nsIWeakReference*
+NS_GetWeakReference( nsISupports* aInstance, nsresult* aResult )
+	{
+		nsIWeakReference* result = 0;
+		nsCOMPtr<nsISupportsWeakReference> factory = do_QueryInterface(aInstance, aResult);
+
+		nsIWeakReference* w
+		if ( factory )
+			result = factory->GetWeakReference();
+		return result;
+	}
+
+nsresult
+nsSupportsWeakReference::GetWeakReference( nsIWeakReference** aInstancePtr )
+	{
+		if ( !aInstancePtr )
+			return NS_ERROR_NULL_POINTER;
+
+		if ( !mProxy )
+			mProxy = new nsWeakReference(this);
+		*aInstancePtr = mProxy;
+
+		nsresult status;
+		if ( !*aInstancePtr )
+			status = NS_NOINTERFACE;
+		else
+			{
+				NS_ADDREF(*aInstancePtr);
+				status = NS_OK;
+			}
+
+		return status;
+	}
+
+nsrefcnt
+nsWeakReference::AddRef()
+	{
+		return ++mRefCount
+	}
+
+nsrefcnt
+nsWeakReference::Release()
+	{
+		nsrefcnt temp = --mRefCount;
+		if ( !mRefCount )
+			delete this;
+		return temp;
+	}
+
+nsresult
+nsWeakReference::QueryInterface( const nsIID& aIID, void** aInstancePtr )
+	{
+		if ( !aInstancePtr )
+			return NS_ERROR_NULL_POINTER;
+
+		if ( aIID.Equals(nsCOMTypeInfo<nsIWeakReference>::GetIID()) )
+			*aInstancePtr = NS_STATIC_CAST(nsIWeakReference*, this);
+		else if ( aIID.Equals(nsCOMTypeInfo<nsISupports>::GetIID()) )
+			*aInstancePtr = NS_STATIC_CAST(nsISupports*, this);
+		else
+			*aInstancePtr = 0;
+
+		nsresult status;
+		if ( !*aInstancePtr )
+			status = NS_NOINTERFACE;
+		else
+			{
+				NS_ADDREF( NS_REINTERPRET_CAST(nsISupports*, *aInstancePtr) );
+				status = NS_OK;
+			}
+
+		return status;
+	}
+
+nsresult
+nsWeakReference::QueryReference( const nsIID& aIID, void** aInstancePtr )
+	{
+		return mReferent ? mReferent->QueryInterface(aIID, aInstancePtr) : NS_ERROR_NULL_PTR;
+	}

xpcom/glue/nsWeakReference.h

@@ -0,0 +1,82 @@
+#ifndef nsWeakReference_h__
+#define nsWeakReference_h__
+
+// nsWeakReference.h
+
+#include "nsIWeakReference.h"
+
+class nsSupportsWeakReference : public nsISupportsWeakReference
+	{
+		public:
+			nsSupportsWeakReference()
+					: mProxy(0)
+				{
+					// nothing else to do here
+				}
+
+			inline ~nsSupportsWeakReference();
+
+			virtual nsresult GetWeakReference( nsIWeakReference** );
+
+		private:
+			friend class nsWeakReference;
+
+			void
+			NoticeProxyDestruction()
+					// ...called (only) by an |nsWeakReference| from _its_ dtor.
+				{
+					mProxy = 0;
+				}
+
+			nsWeakReference* mProxy;
+	};
+
+class nsWeakReference : public nsIWeakReference
+	{
+		public:
+		// nsISupports...
+			virtual nsrefcnt AddRef();
+			virtual nsrefcnt Release();
+			virtual nsresult QueryInterface( const nsIID&, void** );
+
+		// nsIWeakReference...
+			virtual nsresult QueryReference( const nsIID&, void** );
+
+
+		private:
+			friend class nsSupportsWeakReference;
+
+			nsWeakReference( nsSupportsWeakReference* referent )
+					: mRefCount(0),
+						mReferent(referent)
+					// ...I can only be constructed by an |nsSupportsWeakReference|
+				{
+					// nothing else to do here
+				}
+
+		 ~nsWeakReference()
+		 			// ...I will only be destroyed by calling |delete| myself.
+				{
+					if ( mReferent )
+						mReferent->NoticeProxyDestruction();
+				}
+
+			void
+			NoticeReferentDestruction()
+					// ...called (only) by an |nsSupportsWeakReference| from _its_ dtor.
+				{
+					mReferent = 0;
+				}
+
+			nsrefcnt									mRefCount;
+			nsSupportsWeakReference*	mReferent;
+	};
+
+inline
+nsSupportsWeakReference::~nsSupportsWeakReference()
+	{
+		if ( mProxy )
+			mProxy->NoticeReferentDestruction();
+	}
+
+#endif