gecko-dev/xpcom/base/nsCWeakReference.cpp

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1999-10-01 02:38:41 +00:00
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* The contents of this file are subject to the Netscape Public License
* Version 1.0 (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/NPL/
*
* 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 Communicator client code,
* released March 31, 1998.
*
* The Initial Developer of the Original Code is Netscape Communications
* Corporation. Portions created by Netscape are
* Copyright (C) 1998 Netscape Communications Corporation. All Rights
* Reserved.
*
* Contributors:
*/
/* A set of support classes for defining weak references, rather like
nsIWeakReference, but for use with non-COM objects
*/
#include "nsCWeakReference.h"
/************ a thing supporting weak references to itself ***********/
nsCWeakReferent::nsCWeakReferent(void *aRealThing) :
mRealThing(aRealThing),
mProxy(0) {
}
nsCWeakReferent::~nsCWeakReferent() {
if (mProxy)
mProxy->RealThingDeleted();
}
void nsCWeakReferent::SetReferent(void *aRealThing) {
NS_ASSERTION(!mRealThing && !mProxy, "weak referent set twice");
mRealThing = aRealThing;
mProxy = 0;
}
nsCWeakProxy *nsCWeakReferent::GetProxy() {
if (!mProxy)
mProxy = new nsCWeakProxy(mRealThing, this);
return mProxy;
}
/************ a reference proxy whose lifetime we control ***********/
/* the nsCWeakProxy object is an object whose creation and lifetime is
under our control, unlike the nsCWeakReferent and its family of
nsCWeakReferences. An nsCWeakProxy is created by the nsCWeakReferent
when the first weak reference is necessary, and refcounted for each
additional reference. It knows about the lifetime of the nsCWeakReferent,
and deletes itself once all weak references have been broken.
*/
nsCWeakProxy::nsCWeakProxy(void *aRealThing, nsCWeakReferent *aReferent) :
mRealPointer(aRealThing),
mReferent(aReferent),
mRefCount(0) {
NS_ASSERTION(aRealThing && aReferent, "weak proxy constructed with null ptr");
}
nsCWeakProxy::~nsCWeakProxy() {
if (mReferent)
mReferent->ProxyDeleted();
}
void nsCWeakProxy::ReleaseReference() {
if (--mRefCount == 0) {
delete this;
}
}