gecko-dev/xpcom/glue/nsIWeakReferenceUtils.h

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/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Scott Collins <scc@mozilla.org> (Original Author)
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
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* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef nsIWeakReferenceUtils_h__
#define nsIWeakReferenceUtils_h__
#ifndef nsCOMPtr_h__
#include "nsCOMPtr.h"
#endif
typedef nsCOMPtr<nsIWeakReference> nsWeakPtr;
/**
*
*/
// a type-safe shortcut for calling the |QueryReferent()| member function
// T must inherit from nsIWeakReference, but the cast may be ambiguous.
template <class T, class DestinationType>
inline
nsresult
CallQueryReferent( T* aSource, DestinationType** aDestination )
{
NS_PRECONDITION(aSource, "null parameter");
NS_PRECONDITION(aDestination, "null parameter");
return aSource->QueryReferent(NS_GET_TEMPLATE_IID(DestinationType),
reinterpret_cast<void**>(aDestination));
}
class NS_COM_GLUE nsQueryReferent : public nsCOMPtr_helper
{
public:
nsQueryReferent( nsIWeakReference* aWeakPtr, nsresult* error )
: mWeakPtr(aWeakPtr),
mErrorPtr(error)
{
// nothing else to do here
}
virtual nsresult NS_FASTCALL operator()( const nsIID& aIID, void** ) const;
private:
nsIWeakReference* mWeakPtr;
nsresult* mErrorPtr;
};
inline
const nsQueryReferent
do_QueryReferent( nsIWeakReference* aRawPtr, nsresult* error = 0 )
{
return nsQueryReferent(aRawPtr, error);
}
/**
* Deprecated, use |do_GetWeakReference| instead.
*/
extern NS_COM_GLUE
nsIWeakReference*
NS_GetWeakReference( nsISupports* , nsresult* aResult=0 );
/**
* |do_GetWeakReference| is a convenience function that bundles up all the work needed
* to get a weak reference to an arbitrary object, i.e., the |QueryInterface|, test, and
* call through to |GetWeakReference|, and put it into your |nsCOMPtr|.
* It is specifically designed to cooperate with |nsCOMPtr| (or |nsWeakPtr|) like so:
* |nsWeakPtr myWeakPtr = do_GetWeakReference(aPtr);|.
*/
inline
already_AddRefed<nsIWeakReference>
do_GetWeakReference( nsISupports* aRawPtr, nsresult* error = 0 )
{
return NS_GetWeakReference(aRawPtr, error);
}
inline
void
do_GetWeakReference( nsIWeakReference* aRawPtr, nsresult* error = 0 )
{
// This signature exists solely to _stop_ you from doing a bad thing.
// Saying |do_GetWeakReference()| on a weak reference itself,
// is very likely to be a programmer error.
}
template <class T>
inline
void
do_GetWeakReference( already_AddRefed<T>& )
{
// This signature exists solely to _stop_ you from doing the bad thing.
// Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
// someone else is an automatic leak. See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
}
template <class T>
inline
void
do_GetWeakReference( already_AddRefed<T>&, nsresult* )
{
// This signature exists solely to _stop_ you from doing the bad thing.
// Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
// someone else is an automatic leak. See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
}
#endif