RetroZilla/xpcom/ds/nsObserverList.cpp

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2015-10-21 05:03:22 +02:00
/* -*- 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):
*
* 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 ***** */
#define NS_WEAK_OBSERVERS
#include "pratom.h"
#include "nsString.h"
#include "nsAutoLock.h"
#include "nsCOMPtr.h"
#include "nsIWeakReference.h"
#include "nsEnumeratorUtils.h"
#include "nsObserverList.h"
nsObserverList::nsObserverList()
{
MOZ_COUNT_CTOR(nsObserverList);
mLock = PR_NewLock();
}
nsObserverList::~nsObserverList(void)
{
MOZ_COUNT_DTOR(nsObserverList);
PR_DestroyLock(mLock);
}
nsresult
nsObserverList::AddObserver(nsIObserver* anObserver, PRBool ownsWeak)
{
nsresult rv;
PRBool inserted;
NS_ENSURE_ARG(anObserver);
nsAutoLock lock(mLock);
if (!mObserverList) {
rv = NS_NewISupportsArray(getter_AddRefs(mObserverList));
if (NS_FAILED(rv)) return rv;
}
#ifdef NS_WEAK_OBSERVERS
nsCOMPtr<nsISupports> observerRef;
if (ownsWeak) {
nsCOMPtr<nsISupportsWeakReference> weakRefFactory = do_QueryInterface(anObserver);
NS_ASSERTION(weakRefFactory, "AddObserver: trying weak object that doesnt support nsIWeakReference");
if ( weakRefFactory )
observerRef = getter_AddRefs(NS_STATIC_CAST(nsISupports*, NS_GetWeakReference(weakRefFactory)));
} else {
#if DEBUG_dougt_xxx
// if you are hitting this assertion, contact dougt@netscape.com. There may be a ownership problem caused by his checkin to freeze nsIObserver
nsCOMPtr<nsISupportsWeakReference> weakRefFactory = do_QueryInterface(anObserver);
NS_ASSERTION(!weakRefFactory, "Your object supports weak references, but is being added with a strong reference");
#endif
observerRef = anObserver;
}
if (!observerRef)
return NS_ERROR_FAILURE;
inserted = mObserverList->AppendElement(observerRef);
#else
if (*anObserver)
inserted = mObserverList->AppendElement(*anObserver);
#endif
return inserted ? NS_OK : NS_ERROR_FAILURE;
}
nsresult
nsObserverList::RemoveObserver(nsIObserver* anObserver)
{
PRBool removed = PR_FALSE;
NS_ENSURE_ARG(anObserver);
// Prevent the observer from being destroyed while we're inside the lock.
nsCOMPtr<nsIObserver> kungFuDeathGrip(anObserver);
#ifdef NS_WEAK_OBSERVERS
// Get the weak ref before we acquire the lock, because this QI could
// run any arbitrary JS code
nsCOMPtr<nsISupportsWeakReference> weakRefFactory = do_QueryInterface(anObserver);
nsCOMPtr<nsISupports> observerRef;
if (weakRefFactory) {
observerRef = getter_AddRefs(NS_STATIC_CAST(nsISupports*, NS_GetWeakReference(weakRefFactory)));
}
nsAutoLock lock(mLock);
if (!mObserverList)
return NS_ERROR_FAILURE;
if (observerRef) {
removed = mObserverList->RemoveElement(observerRef);
}
if (!removed && anObserver) {
removed = mObserverList->RemoveElement(anObserver);
}
#else
nsAutoLock lock(mLock);
if (!mObserverList)
return NS_ERROR_FAILURE;
if (*anObserver)
removed = mObserverList->RemoveElement(*anObserver);
#endif
return removed ? NS_OK : NS_ERROR_FAILURE;
}
nsresult
nsObserverList::GetObserverList(nsISimpleEnumerator** anEnumerator)
{
nsAutoLock lock(mLock);
ObserverListEnumerator * enumerator= new ObserverListEnumerator(mObserverList);
*anEnumerator = enumerator;
if (!enumerator)
return NS_ERROR_OUT_OF_MEMORY;
NS_ADDREF(enumerator);
return NS_OK;
}
ObserverListEnumerator::ObserverListEnumerator(nsISupportsArray* aValueArray)
: mValueArray(aValueArray), mIndex(0)
{
if (mValueArray) {
NS_ADDREF(mValueArray);
PRUint32 total;
mValueArray->Count(&total);
mIndex = PRInt32(total);
}
}
ObserverListEnumerator::~ObserverListEnumerator(void)
{
NS_IF_RELEASE(mValueArray);
}
NS_IMPL_ISUPPORTS1(ObserverListEnumerator, nsISimpleEnumerator)
NS_IMETHODIMP
ObserverListEnumerator::HasMoreElements(PRBool* aResult)
{
NS_PRECONDITION(aResult != 0, "null ptr");
if (! aResult)
return NS_ERROR_NULL_POINTER;
if (!mValueArray) {
*aResult = PR_FALSE;
return NS_OK;
}
*aResult = (mIndex > 0);
return NS_OK;
}
NS_IMETHODIMP
ObserverListEnumerator::GetNext(nsISupports** aResult)
{
NS_PRECONDITION(aResult != 0, "null ptr");
if (! aResult)
return NS_ERROR_NULL_POINTER;
if (!mValueArray) {
*aResult = nsnull;
return NS_OK;
}
if (mIndex <= 0 )
return NS_ERROR_UNEXPECTED;
mValueArray->GetElementAt(--mIndex, aResult);
if (*aResult) {
nsCOMPtr<nsIWeakReference> weakRefFactory = do_QueryInterface(*aResult);
if ( weakRefFactory ) {
nsCOMPtr<nsISupports> weakref = do_QueryReferent(weakRefFactory);
NS_RELEASE(*aResult);
NS_IF_ADDREF(*aResult = weakref);
return NS_OK;
}
}
return NS_OK;
}