RetroZilla/xpcom/glue/nsWeakReference.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* ***** 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 the Mozilla browser.
*
* The Initial Developer of the Original Code is
* Netscape Communications, Inc.
* Portions created by the Initial Developer are Copyright (C) 1999
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Scott Collins <scc@netscape.com>
*
* 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 nsWeakReference_h__
#define nsWeakReference_h__
// nsWeakReference.h
#include "nsIWeakReference.h"
#include "nsIWeakReferenceUtils.h"
class nsWeakReference;
#undef IMETHOD_VISIBILITY
#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT
class NS_COM_GLUE nsSupportsWeakReference : public nsISupportsWeakReference
{
public:
nsSupportsWeakReference()
: mProxy(0)
{
// nothing else to do here
}
NS_DECL_NSISUPPORTSWEAKREFERENCE
protected:
inline ~nsSupportsWeakReference();
private:
friend class nsWeakReference;
void
NoticeProxyDestruction()
// ...called (only) by an |nsWeakReference| from _its_ dtor.
{
mProxy = 0;
}
nsWeakReference* mProxy;
protected:
inline void ClearWeakReferences();
PRBool HasWeakReferences() const {return mProxy != 0;}
};
#undef IMETHOD_VISIBILITY
#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN
class NS_COM_GLUE nsWeakReference : public nsIWeakReference
{
public:
// nsISupports...
NS_DECL_ISUPPORTS
// nsIWeakReference...
NS_DECL_NSIWEAKREFERENCE
private:
friend class nsSupportsWeakReference;
nsWeakReference( nsSupportsWeakReference* referent )
: mReferent(referent)
// ...I can only be constructed by an |nsSupportsWeakReference|
{
// nothing else to do here
}
~nsWeakReference()
// ...I will only be destroyed by calling |delete| myself.
{
if ( mReferent )
mReferent->NoticeProxyDestruction();
}
void
NoticeReferentDestruction()
// ...called (only) by an |nsSupportsWeakReference| from _its_ dtor.
{
mReferent = 0;
}
nsSupportsWeakReference* mReferent;
};
inline
void
nsSupportsWeakReference::ClearWeakReferences()
/*
Usually being called from |nsSupportsWeakReference::~nsSupportsWeakReference|
will be good enough, but you may have a case where you need to call disconnect
your weak references in an outer destructor (to prevent some client holding a
weak reference from re-entering your destructor).
*/
{
if ( mProxy )
{
mProxy->NoticeReferentDestruction();
mProxy = 0;
}
}
inline
nsSupportsWeakReference::~nsSupportsWeakReference()
{
ClearWeakReferences();
}
#endif