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/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the Qt3Support module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia. For licensing terms and
** conditions see http://qt.digia.com/licensing. For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights. These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "q3deepcopy.h"
QT_BEGIN_NAMESPACE
/*!
\class Q3DeepCopy
\brief The Q3DeepCopy class is a template class which ensures that
implicitly shared and explicitly shared classes reference unique
data.
\reentrant
\compat
Normally, shared copies reference the same data to optimize memory
use and for maximum speed. In the example below, \c s1, \c s2, \c
s3, \c s4 and \c s5 share data.
\snippet doc/src/snippets/code/src_qt3support_tools_q3deepcopy.cpp 0
Q3DeepCopy can be used several ways to ensure that an object
references unique, unshared data. In the example below, \c s1, \c
s2 and \c s5 share data, while neither \c s3 nor \c s4 share data.
\snippet doc/src/snippets/code/src_qt3support_tools_q3deepcopy.cpp 1
In the example below, \c s1, \c s2 and \c s5 share data, and \c s3
and \c s4 share data.
\snippet doc/src/snippets/code/src_qt3support_tools_q3deepcopy.cpp 2
Q3DeepCopy can also provide safety in multithreaded applications
that use shared classes. In the example below, the variable \c
global_string is used safely since the data contained in \c
global_string is always a deep copy. This ensures that all threads
get a unique copy of the data, and that any assignments to \c
global_string will result in a deep copy.
\snippet doc/src/snippets/code/src_qt3support_tools_q3deepcopy.cpp 3
\warning It is the application developer's responsibility to
protect the object shared across multiple threads.
The examples above use QString, which is an implicitly shared
class. The behavior of Q3DeepCopy is the same when using explicitly
shared classes like QByteArray.
Currently, Q3DeepCopy works with the following classes:
\list
\i QMemArray (including subclasses like QByteArray and QCString)
\i QMap
\i QString
\i QValueList (including subclasses like QStringList and QValueStack)
\i QValueVector
\endlist
\sa \link threads.html Thread Support in Qt \endlink
*/
/*!
\fn Q3DeepCopy::Q3DeepCopy()
Constructs an empty instance of type \e T.
*/
/*!
\fn Q3DeepCopy::Q3DeepCopy( const T &t )
Constructs a deep copy of \a t.
*/
/*!
\fn Q3DeepCopy<T>& Q3DeepCopy::operator=( const T &t )
Assigns a deep copy of \a t.
*/
/*!
\fn Q3DeepCopy::operator T ()
Returns a deep copy of the encapsulated data.
*/
QT_END_NAMESPACE
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