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