michael@0: /* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef nsIWeakReferenceUtils_h__
michael@0: #define nsIWeakReferenceUtils_h__
michael@0: 
michael@0: #include "nsCOMPtr.h"
michael@0: #include "nsIWeakReference.h"
michael@0: 
michael@0: typedef nsCOMPtr<nsIWeakReference> nsWeakPtr;
michael@0: 
michael@0: /**
michael@0:  *
michael@0:  */
michael@0: 
michael@0: // a type-safe shortcut for calling the |QueryReferent()| member function
michael@0: // T must inherit from nsIWeakReference, but the cast may be ambiguous.
michael@0: template <class T, class DestinationType>
michael@0: inline
michael@0: nsresult
michael@0: CallQueryReferent( T* aSource, DestinationType** aDestination )
michael@0:   {
michael@0:     NS_PRECONDITION(aSource, "null parameter");
michael@0:     NS_PRECONDITION(aDestination, "null parameter");
michael@0: 
michael@0:     return aSource->QueryReferent(NS_GET_TEMPLATE_IID(DestinationType),
michael@0:                                   reinterpret_cast<void**>(aDestination));
michael@0:   }
michael@0: 
michael@0: 
michael@0: class NS_COM_GLUE nsQueryReferent : public nsCOMPtr_helper
michael@0:   {
michael@0:     public:
michael@0:       nsQueryReferent( nsIWeakReference* aWeakPtr, nsresult* error )
michael@0:           : mWeakPtr(aWeakPtr),
michael@0:             mErrorPtr(error)
michael@0:         {
michael@0:           // nothing else to do here
michael@0:         }
michael@0: 
michael@0:       virtual nsresult NS_FASTCALL operator()( const nsIID& aIID, void** ) const;
michael@0: 
michael@0:     private:
michael@0:       nsIWeakReference*  mWeakPtr;
michael@0:       nsresult*          mErrorPtr;
michael@0:   };
michael@0: 
michael@0: inline
michael@0: const nsQueryReferent
michael@0: do_QueryReferent( nsIWeakReference* aRawPtr, nsresult* error = 0 )
michael@0:   {
michael@0:     return nsQueryReferent(aRawPtr, error);
michael@0:   }
michael@0: 
michael@0: 
michael@0:   /**
michael@0:    * Deprecated, use |do_GetWeakReference| instead.
michael@0:    */
michael@0: extern NS_COM_GLUE
michael@0: nsIWeakReference*
michael@0: NS_GetWeakReference( nsISupports* , nsresult* aResult=0 );
michael@0: 
michael@0:   /**
michael@0:    * |do_GetWeakReference| is a convenience function that bundles up all the work needed
michael@0:    * to get a weak reference to an arbitrary object, i.e., the |QueryInterface|, test, and
michael@0:    * call through to |GetWeakReference|, and put it into your |nsCOMPtr|.
michael@0:    * It is specifically designed to cooperate with |nsCOMPtr| (or |nsWeakPtr|) like so:
michael@0:    * |nsWeakPtr myWeakPtr = do_GetWeakReference(aPtr);|.
michael@0:    */
michael@0: inline
michael@0: already_AddRefed<nsIWeakReference>
michael@0: do_GetWeakReference( nsISupports* aRawPtr, nsresult* error = 0 )
michael@0:   {
michael@0:     return dont_AddRef(NS_GetWeakReference(aRawPtr, error));
michael@0:   }
michael@0: 
michael@0: inline
michael@0: void
michael@0: do_GetWeakReference( nsIWeakReference* aRawPtr, nsresult* error = 0 )
michael@0:   {
michael@0:     // This signature exists solely to _stop_ you from doing a bad thing.
michael@0:     //  Saying |do_GetWeakReference()| on a weak reference itself,
michael@0:     //  is very likely to be a programmer error.
michael@0:   }
michael@0: 
michael@0: template <class T>
michael@0: inline
michael@0: void
michael@0: do_GetWeakReference( already_AddRefed<T>& )
michael@0:   {
michael@0:     // This signature exists solely to _stop_ you from doing the bad thing.
michael@0:     //  Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
michael@0:     //  someone else is an automatic leak.  See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
michael@0:   }
michael@0: 
michael@0: template <class T>
michael@0: inline
michael@0: void
michael@0: do_GetWeakReference( already_AddRefed<T>&, nsresult* )
michael@0:   {
michael@0:     // This signature exists solely to _stop_ you from doing the bad thing.
michael@0:     //  Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
michael@0:     //  someone else is an automatic leak.  See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
michael@0:   }
michael@0: 
michael@0: #endif