231 lines
7.8 KiB
C++
231 lines
7.8 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is mozilla.org code.
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 1998
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Pierre Phaneuf <pp@ludusdesign.com>
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* Scott Collins <scc@ScottCollins.net>
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* Dan Mosedale <dmose@mozilla.org>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either of the GNU General Public License Version 2 or later (the "GPL"),
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* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#ifndef nsISupportsUtils_h__
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#define nsISupportsUtils_h__
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#ifndef nscore_h___
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#include "nscore.h"
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#endif
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#ifndef nsISupportsBase_h__
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#include "nsISupportsBase.h"
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#endif
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#ifndef nsError_h__
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#include "nsError.h"
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#endif
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#ifndef nsDebug_h___
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#include "nsDebug.h"
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#endif
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#ifndef nsISupportsImpl_h__
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#include "nsISupportsImpl.h"
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#endif
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/**
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* Macro for instantiating a new object that implements nsISupports.
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* Note that you can only use this if you adhere to the no arguments
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* constructor com policy (which you really should!).
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* @param _result Where the new instance pointer is stored
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* @param _type The type of object to call "new" with.
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*/
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#define NS_NEWXPCOM(_result,_type) \
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PR_BEGIN_MACRO \
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_result = new _type(); \
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PR_END_MACRO
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/**
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* Macro for deleting an object that implements nsISupports.
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* @param _ptr The object to delete.
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*/
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#define NS_DELETEXPCOM(_ptr) \
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PR_BEGIN_MACRO \
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delete (_ptr); \
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PR_END_MACRO
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/**
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* Macro for adding a reference to an interface.
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* @param _ptr The interface pointer.
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*/
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#define NS_ADDREF(_ptr) \
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(_ptr)->AddRef()
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/**
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* Macro for adding a reference to this. This macro should be used
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* because NS_ADDREF (when tracing) may require an ambiguous cast
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* from the pointers primary type to nsISupports. This macro sidesteps
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* that entire problem.
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*/
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#define NS_ADDREF_THIS() \
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AddRef()
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extern "C++" {
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// ...because some one is accidentally including this file inside
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// an |extern "C"|
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// Making this a |inline| |template| allows |expr| to be evaluated only once,
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// yet still denies you the ability to |AddRef()| an |nsCOMPtr|.
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template <class T>
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inline
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nsrefcnt
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ns_if_addref( T expr )
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{
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return expr ? expr->AddRef() : 0;
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}
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} /* extern "C++" */
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/**
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* Macro for adding a reference to an interface that checks for NULL.
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* @param _expr The interface pointer.
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*/
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#define NS_IF_ADDREF(_expr) ns_if_addref(_expr)
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/*
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* Given these declarations, it explicitly OK and efficient to end a `getter' with:
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*
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* NS_IF_ADDREF(*result = mThing);
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*
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* even if |mThing| is an |nsCOMPtr|. If |mThing| is an |nsCOMPtr|, however, it is still
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* _illegal_ to say |NS_IF_ADDREF(mThing)|.
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*/
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/**
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* Macro for releasing a reference to an interface.
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* @param _ptr The interface pointer.
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*/
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#define NS_RELEASE(_ptr) \
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PR_BEGIN_MACRO \
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(_ptr)->Release(); \
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(_ptr) = 0; \
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PR_END_MACRO
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/**
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* Macro for releasing a reference to an interface.
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* @param _ptr The interface pointer.
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*/
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#define NS_RELEASE_THIS() \
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Release()
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/**
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* Macro for releasing a reference to an interface, except that this
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* macro preserves the return value from the underlying Release call.
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* The interface pointer argument will only be NULLed if the reference count
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* goes to zero.
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*
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* @param _ptr The interface pointer.
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*/
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#define NS_RELEASE2(_ptr,_rv) \
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PR_BEGIN_MACRO \
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_rv = (_ptr)->Release(); \
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if (0 == (_rv)) (_ptr) = 0; \
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PR_END_MACRO
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/**
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* Macro for releasing a reference to an interface that checks for NULL;
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* @param _ptr The interface pointer.
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*/
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#define NS_IF_RELEASE(_ptr) \
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PR_BEGIN_MACRO \
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if (_ptr) { \
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(_ptr)->Release(); \
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(_ptr) = 0; \
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} \
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PR_END_MACRO
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/*
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* Often you have to cast an implementation pointer, e.g., |this|, to an
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* |nsISupports*|, but because you have multiple inheritance, a simple cast
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* is ambiguous. One could simply say, e.g., (given a base |nsIBase|),
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* |NS_STATIC_CAST(nsIBase*, this)|; but that disguises the fact that what
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* you are really doing is disambiguating the |nsISupports|. You could make
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* that more obvious with a double cast, e.g., |NS_STATIC_CAST(nsISupports*,
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* NS_STATIC_CAST(nsIBase*, this))|, but that is bulky and harder to read...
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*
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* The following macro is clean, short, and obvious. In the example above,
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* you would use it like this: |NS_ISUPPORTS_CAST(nsIBase*, this)|.
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*/
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#define NS_ISUPPORTS_CAST(__unambiguousBase, __expr) \
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NS_STATIC_CAST(nsISupports*, NS_STATIC_CAST(__unambiguousBase, __expr))
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extern "C++" {
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// ...because some one is accidentally including this file inside
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// an |extern "C"|
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class nsISupports;
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template <class T>
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struct nsCOMTypeInfo
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{
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static const nsIID& GetIID() { return T::GetIID(); }
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};
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NS_SPECIALIZE_TEMPLATE
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struct nsCOMTypeInfo<nsISupports>
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{
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static const nsIID& GetIID() {
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static const nsIID iid_NS_ISUPPORTS_IID = NS_ISUPPORTS_IID; return iid_NS_ISUPPORTS_IID;
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}
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};
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#define NS_GET_IID(T) nsCOMTypeInfo<T>::GetIID()
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// a type-safe shortcut for calling the |QueryInterface()| member function
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template <class T, class DestinationType>
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inline
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nsresult
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CallQueryInterface( 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->QueryInterface(NS_GET_IID(DestinationType),
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NS_REINTERPRET_CAST(void**, aDestination));
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}
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} // extern "C++"
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#endif /* __nsISupportsUtils_h */
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