src/corelib/kernel/qobjectcleanuphandler.cpp
author Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
Fri, 19 Feb 2010 23:40:16 +0200
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/****************************************************************************
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**
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** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
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** All rights reserved.
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** Contact: Nokia Corporation (qt-info@nokia.com)
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**
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** This file is part of the QtCore module of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** No Commercial Usage
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** This file contains pre-release code and may not be distributed.
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** You may use this file in accordance with the terms and conditions
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** contained in the Technology Preview License Agreement accompanying
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** this package.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 2.1 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL included in the
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** packaging of this file.  Please review the following information to
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** ensure the GNU Lesser General Public License version 2.1 requirements
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** In addition, as a special exception, Nokia gives you certain additional
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** rights.  These rights are described in the Nokia Qt LGPL Exception
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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**
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** If you have questions regarding the use of this file, please contact
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** Nokia at qt-info@nokia.com.
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**
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**
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**
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**
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**
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**
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**
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include "qobjectcleanuphandler.h"
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QT_BEGIN_NAMESPACE
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/*!
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    \class QObjectCleanupHandler
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    \brief The QObjectCleanupHandler class watches the lifetime of multiple QObjects.
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    \ingroup objectmodel
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    A QObjectCleanupHandler is useful whenever you need to know when a
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    number of \l{QObject}s that are owned by someone else have been
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    deleted. This is important, for example, when referencing memory
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    in an application that has been allocated in a shared library.
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    To keep track of some \l{QObject}s, create a
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    QObjectCleanupHandler, and add() the objects you are interested
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    in. If you are no longer interested in tracking a particular
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    object, use remove() to remove it from the cleanup handler. If an
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    object being tracked by the cleanup handler gets deleted by
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    someone else it will automatically be removed from the cleanup
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    handler. You can delete all the objects in the cleanup handler
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    with clear(), or by destroying the cleanup handler. isEmpty()
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    returns true if the QObjectCleanupHandler has no objects to keep
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    track of.
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    \sa QPointer
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*/
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/*!
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    Constructs an empty QObjectCleanupHandler.
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*/
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QObjectCleanupHandler::QObjectCleanupHandler()
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{
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}
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/*!
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    Destroys the cleanup handler. All objects in this cleanup handler
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    will be deleted.
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    \sa clear()
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*/
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QObjectCleanupHandler::~QObjectCleanupHandler()
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{
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    clear();
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}
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/*!
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    Adds \a object to this cleanup handler and returns the pointer to
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    the object.
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    \sa remove()
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*/
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QObject *QObjectCleanupHandler::add(QObject* object)
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{
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    if (!object)
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        return 0;
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    connect(object, SIGNAL(destroyed(QObject*)), this, SLOT(objectDestroyed(QObject*)));
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    cleanupObjects.insert(0, object);
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    return object;
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}
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/*!
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    Removes the \a object from this cleanup handler. The object will
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    not be destroyed.
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    \sa add()
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*/
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void QObjectCleanupHandler::remove(QObject *object)
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{
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    int index;
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    if ((index = cleanupObjects.indexOf(object)) != -1) {
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        cleanupObjects.removeAt(index);
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        disconnect(object, SIGNAL(destroyed(QObject*)), this, SLOT(objectDestroyed(QObject*)));
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    }
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}
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/*!
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    Returns true if this cleanup handler is empty or if all objects in
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    this cleanup handler have been destroyed; otherwise return false.
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    \sa add() remove() clear()
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*/
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bool QObjectCleanupHandler::isEmpty() const
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{
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    return cleanupObjects.isEmpty();
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}
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/*!
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    Deletes all objects in this cleanup handler. The cleanup handler
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    becomes empty.
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    \sa isEmpty()
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*/
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void QObjectCleanupHandler::clear()
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{
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    while (!cleanupObjects.isEmpty())
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        delete cleanupObjects.takeFirst();
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}
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void QObjectCleanupHandler::objectDestroyed(QObject *object)
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{
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    remove(object);
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}
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QT_END_NAMESPACE