forked from mirrors/gecko-dev
af69df0b21
NS_GetWeakReference, called from do_GetWeakReference, QI's its argument to nsISupportsWeakReference to determine whether a weak reference can be obtained. If NS_GetWeakReference is already receiving a nsISupportsWeakReference pointer, or something than can be converted to one, then we can skip the QI for a small performance win.
93 lines
3.1 KiB
C++
93 lines
3.1 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsIWeakReferenceUtils_h__
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#define nsIWeakReferenceUtils_h__
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#include "nsCOMPtr.h"
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#include "nsIWeakReference.h"
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typedef nsCOMPtr<nsIWeakReference> nsWeakPtr;
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/**
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*
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*/
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// a type-safe shortcut for calling the |QueryReferent()| member function
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// T must inherit from nsIWeakReference, but the cast may be ambiguous.
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template<class T, class DestinationType>
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inline nsresult
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CallQueryReferent(T* aSource, DestinationType** aDestination)
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{
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NS_PRECONDITION(aSource, "null parameter");
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NS_PRECONDITION(aDestination, "null parameter");
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return aSource->QueryReferent(NS_GET_TEMPLATE_IID(DestinationType),
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reinterpret_cast<void**>(aDestination));
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}
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inline const nsQueryReferent
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do_QueryReferent(nsIWeakReference* aRawPtr, nsresult* aError = 0)
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{
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return nsQueryReferent(aRawPtr, aError);
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}
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/**
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* Deprecated, use |do_GetWeakReference| instead.
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*/
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extern nsIWeakReference* NS_GetWeakReference(nsISupports*,
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nsresult* aResult = 0);
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extern nsIWeakReference* NS_GetWeakReference(nsISupportsWeakReference*,
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nsresult* aResult = 0);
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/**
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* |do_GetWeakReference| is a convenience function that bundles up all the work needed
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* to get a weak reference to an arbitrary object, i.e., the |QueryInterface|, test, and
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* call through to |GetWeakReference|, and put it into your |nsCOMPtr|.
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* It is specifically designed to cooperate with |nsCOMPtr| (or |nsWeakPtr|) like so:
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* |nsWeakPtr myWeakPtr = do_GetWeakReference(aPtr);|.
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*/
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inline already_AddRefed<nsIWeakReference>
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do_GetWeakReference(nsISupports* aRawPtr, nsresult* aError = 0)
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{
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return dont_AddRef(NS_GetWeakReference(aRawPtr, aError));
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}
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inline already_AddRefed<nsIWeakReference>
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do_GetWeakReference(nsISupportsWeakReference* aRawPtr, nsresult* aError = 0)
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{
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return dont_AddRef(NS_GetWeakReference(aRawPtr, aError));
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}
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inline void
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do_GetWeakReference(nsIWeakReference* aRawPtr, nsresult* aError = 0)
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{
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// This signature exists solely to _stop_ you from doing a bad thing.
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// Saying |do_GetWeakReference()| on a weak reference itself,
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// is very likely to be a programmer error.
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}
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template<class T>
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inline void
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do_GetWeakReference(already_AddRefed<T>&)
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{
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// This signature exists solely to _stop_ you from doing the bad thing.
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// Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
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// someone else is an automatic leak. See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
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}
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template<class T>
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inline void
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do_GetWeakReference(already_AddRefed<T>&, nsresult*)
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{
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// This signature exists solely to _stop_ you from doing the bad thing.
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// Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
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// someone else is an automatic leak. See <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
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}
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#endif
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