1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
3 /* This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this
5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6
7 #ifndef nsIWeakReferenceUtils_h__
8 #define nsIWeakReferenceUtils_h__
9
10 #include "nsCOMPtr.h"
11 #include "nsIWeakReference.h"
12
13 typedef nsCOMPtr<nsIWeakReference> nsWeakPtr;
14
15 /**
16 *
17 */
18
19 // a type-safe shortcut for calling the |QueryReferent()| member function
20 // T must inherit from nsIWeakReference, but the cast may be ambiguous.
21 template <class T, class DestinationType>
CallQueryReferent(T * aSource,DestinationType ** aDestination)22 inline nsresult CallQueryReferent(T* aSource, DestinationType** aDestination) {
23 MOZ_ASSERT(aSource, "null parameter");
24 MOZ_ASSERT(aDestination, "null parameter");
25
26 return aSource->QueryReferent(NS_GET_TEMPLATE_IID(DestinationType),
27 reinterpret_cast<void**>(aDestination));
28 }
29
30 inline const nsQueryReferent do_QueryReferent(nsIWeakReference* aRawPtr,
31 nsresult* aError = 0) {
32 return nsQueryReferent(aRawPtr, aError);
33 }
34
35 /**
36 * Deprecated, use |do_GetWeakReference| instead.
37 */
38 extern nsIWeakReference* NS_GetWeakReference(nsISupports*,
39 nsresult* aResult = 0);
40 extern nsIWeakReference* NS_GetWeakReference(nsISupportsWeakReference*,
41 nsresult* aResult = 0);
42
43 /**
44 * |do_GetWeakReference| is a convenience function that bundles up all the work
45 * needed to get a weak reference to an arbitrary object, i.e., the
46 * |QueryInterface|, test, and call through to |GetWeakReference|, and put it
47 * into your |nsCOMPtr|. It is specifically designed to cooperate with
48 * |nsCOMPtr| (or |nsWeakPtr|) like so: |nsWeakPtr myWeakPtr =
49 * do_GetWeakReference(aPtr);|.
50 */
51 inline already_AddRefed<nsIWeakReference> do_GetWeakReference(
52 nsISupports* aRawPtr, nsresult* aError = 0) {
53 return dont_AddRef(NS_GetWeakReference(aRawPtr, aError));
54 }
55
56 inline already_AddRefed<nsIWeakReference> do_GetWeakReference(
57 nsISupportsWeakReference* aRawPtr, nsresult* aError = 0) {
58 return dont_AddRef(NS_GetWeakReference(aRawPtr, aError));
59 }
60
61 inline void do_GetWeakReference(nsIWeakReference* aRawPtr,
62 nsresult* aError = 0) {
63 // This signature exists solely to _stop_ you from doing a bad thing.
64 // Saying |do_GetWeakReference()| on a weak reference itself,
65 // is very likely to be a programmer error.
66 }
67
68 template <class T>
do_GetWeakReference(already_AddRefed<T> &)69 inline void do_GetWeakReference(already_AddRefed<T>&) {
70 // This signature exists solely to _stop_ you from doing the bad thing.
71 // Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
72 // someone else is an automatic leak. See
73 // <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
74 }
75
76 template <class T>
do_GetWeakReference(already_AddRefed<T> &,nsresult *)77 inline void do_GetWeakReference(already_AddRefed<T>&, nsresult*) {
78 // This signature exists solely to _stop_ you from doing the bad thing.
79 // Saying |do_GetWeakReference()| on a pointer that is not otherwise owned by
80 // someone else is an automatic leak. See
81 // <http://bugzilla.mozilla.org/show_bug.cgi?id=8221>.
82 }
83
84 #endif
85