1
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2
/* ***** BEGIN LICENSE BLOCK *****
3
* Version: NPL 1.1/GPL 2.0/LGPL 2.1
5
* The contents of this file are subject to the Netscape Public License
6
* Version 1.1 (the "License"); you may not use this file except in
7
* compliance with the License. You may obtain a copy of the License at
8
* http://www.mozilla.org/NPL/
10
* Software distributed under the License is distributed on an "AS IS" basis,
11
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
12
* for the specific language governing rights and limitations under the
15
* The Original Code is mozilla.org code.
17
* The Initial Developer of the Original Code is
18
* Netscape Communications Corporation.
19
* Portions created by the Initial Developer are Copyright (C) 1998
20
* the Initial Developer. All Rights Reserved.
23
* Pierre Phaneuf <pp@ludusdesign.com>
24
* Scott Collins <scc@ScottCollins.net>
25
* Dan Mosedale <dmose@mozilla.org>
27
* Alternatively, the contents of this file may be used under the terms of
28
* either the GNU General Public License Version 2 or later (the "GPL"), or
29
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
30
* in which case the provisions of the GPL or the LGPL are applicable instead
31
* of those above. If you wish to allow use of your version of this file only
32
* under the terms of either the GPL or the LGPL, and not to allow others to
33
* use your version of this file under the terms of the NPL, indicate your
34
* decision by deleting the provisions above and replace them with the notice
35
* and other provisions required by the GPL or the LGPL. If you do not delete
36
* the provisions above, a recipient may use your version of this file under
37
* the terms of any one of the NPL, the GPL or the LGPL.
39
* ***** END LICENSE BLOCK ***** */
41
#ifndef nsISupportsUtils_h__
42
#define nsISupportsUtils_h__
48
#ifndef nsISupportsBase_h__
49
#include "nsISupportsBase.h"
60
#ifndef nsISupportsImpl_h__
61
#include "nsISupportsImpl.h"
65
* Macro for instantiating a new object that implements nsISupports.
66
* Note that you can only use this if you adhere to the no arguments
67
* constructor com policy (which you really should!).
68
* @param _result Where the new instance pointer is stored
69
* @param _type The type of object to call "new" with.
71
#define NS_NEWXPCOM(_result,_type) \
73
_result = new _type(); \
77
* Macro for deleting an object that implements nsISupports.
78
* @param _ptr The object to delete.
80
#define NS_DELETEXPCOM(_ptr) \
86
* Macro for adding a reference to an interface.
87
* @param _ptr The interface pointer.
89
#define NS_ADDREF(_ptr) \
93
* Macro for adding a reference to this. This macro should be used
94
* because NS_ADDREF (when tracing) may require an ambiguous cast
95
* from the pointers primary type to nsISupports. This macro sidesteps
96
* that entire problem.
98
#define NS_ADDREF_THIS() \
103
// ...because some one is accidentally including this file inside
107
// Making this a |inline| |template| allows |expr| to be evaluated only once,
108
// yet still denies you the ability to |AddRef()| an |nsCOMPtr|.
112
ns_if_addref( T expr )
114
return expr ? expr->AddRef() : 0;
120
* Macro for adding a reference to an interface that checks for NULL.
121
* @param _expr The interface pointer.
123
#define NS_IF_ADDREF(_expr) ns_if_addref(_expr)
126
* Given these declarations, it explicitly OK and efficient to end a `getter' with:
128
* NS_IF_ADDREF(*result = mThing);
130
* even if |mThing| is an |nsCOMPtr|. If |mThing| is an |nsCOMPtr|, however, it is still
131
* _illegal_ to say |NS_IF_ADDREF(mThing)|.
135
* Macro for releasing a reference to an interface.
136
* @param _ptr The interface pointer.
138
#define NS_RELEASE(_ptr) \
145
* Macro for releasing a reference to an interface.
146
* @param _ptr The interface pointer.
148
#define NS_RELEASE_THIS() \
152
* Macro for releasing a reference to an interface, except that this
153
* macro preserves the return value from the underlying Release call.
154
* The interface pointer argument will only be NULLed if the reference count
157
* @param _ptr The interface pointer.
159
#define NS_RELEASE2(_ptr,_rv) \
161
_rv = (_ptr)->Release(); \
162
if (0 == (_rv)) (_ptr) = 0; \
166
* Macro for releasing a reference to an interface that checks for NULL;
167
* @param _ptr The interface pointer.
169
#define NS_IF_RELEASE(_ptr) \
178
* Often you have to cast an implementation pointer, e.g., |this|, to an
179
* |nsISupports*|, but because you have multiple inheritance, a simple cast
180
* is ambiguous. One could simply say, e.g., (given a base |nsIBase|),
181
* |NS_STATIC_CAST(nsIBase*, this)|; but that disguises the fact that what
182
* you are really doing is disambiguating the |nsISupports|. You could make
183
* that more obvious with a double cast, e.g., |NS_STATIC_CAST(nsISupports*,
184
* NS_STATIC_CAST(nsIBase*, this))|, but that is bulky and harder to read...
186
* The following macro is clean, short, and obvious. In the example above,
187
* you would use it like this: |NS_ISUPPORTS_CAST(nsIBase*, this)|.
190
#define NS_ISUPPORTS_CAST(__unambiguousBase, __expr) \
191
NS_STATIC_CAST(nsISupports*, NS_STATIC_CAST(__unambiguousBase, __expr))
194
// ...because some one is accidentally including this file inside
202
static const nsIID& GetIID() { return T::GetIID(); }
205
NS_SPECIALIZE_TEMPLATE
206
struct nsCOMTypeInfo<nsISupports>
208
static const nsIID& GetIID() {
209
static const nsIID iid_NS_ISUPPORTS_IID = NS_ISUPPORTS_IID; return iid_NS_ISUPPORTS_IID;
213
#define NS_GET_IID(T) nsCOMTypeInfo<T>::GetIID()
215
// a type-safe shortcut for calling the |QueryInterface()| member function
216
template <class T, class DestinationType>
219
CallQueryInterface( T* aSource, DestinationType** aDestination )
221
NS_PRECONDITION(aSource, "null parameter");
222
NS_PRECONDITION(aDestination, "null parameter");
224
return aSource->QueryInterface(NS_GET_IID(DestinationType),
225
NS_REINTERPRET_CAST(void**, aDestination));
230
#endif /* __nsISupportsUtils_h */