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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef nsIWeakReferenceUtils_h__
#define nsIWeakReferenceUtils_h__
#include "nsCOMPtr.h"
#include "nsIWeakReference.h"
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 MOZ_STACK_CLASS nsQueryReferent final : public nsCOMPtr_helper
{
public:
nsQueryReferent(nsIWeakReference* aWeakPtr, nsresult* aError)
: mWeakPtr(aWeakPtr)
, mErrorPtr(aError)
{
}
virtual nsresult NS_FASTCALL operator()(const nsIID& aIID, void**) const
override;
private:
nsIWeakReference* MOZ_NON_OWNING_REF mWeakPtr;
nsresult* mErrorPtr;
};
inline const nsQueryReferent
do_QueryReferent(nsIWeakReference* aRawPtr, nsresult* aError = 0)
{
return nsQueryReferent(aRawPtr, aError);
}
/**
* Deprecated, use |do_GetWeakReference| instead.
*/
extern 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* aError = 0)
{
return dont_AddRef(NS_GetWeakReference(aRawPtr, aError));
}
inline void
do_GetWeakReference(nsIWeakReference* aRawPtr, nsresult* aError = 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
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