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169 lines
5.2 KiB
169 lines
5.2 KiB
/****************************************************************************
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**
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** Implementation of TQDeepCopy class
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**
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** Created : 20020613
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**
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** Copyright (C) 1992-2008 Trolltech ASA. All rights reserved.
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**
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** This file is part of the kernel module of the TQt GUI Toolkit.
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**
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** This file may be used under the terms of the GNU General
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** Public License versions 2.0 or 3.0 as published by the Free
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** Software Foundation and appearing in the files LICENSE.GPL2
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** and LICENSE.GPL3 included in the packaging of this file.
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** Alternatively you may (at your option) use any later version
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** of the GNU General Public License if such license has been
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** publicly approved by Trolltech ASA (or its successors, if any)
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** and the KDE Free TQt Foundation.
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**
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** Please review the following information to ensure GNU General
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** Public Licensing requirements will be met:
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** http://trolltech.com/products/qt/licenses/licensing/opensource/.
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** If you are unsure which license is appropriate for your use, please
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** review the following information:
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** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
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** or contact the sales department at sales@trolltech.com.
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**
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** This file may be used under the terms of the Q Public License as
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** defined by Trolltech ASA and appearing in the file LICENSE.TQPL
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** included in the packaging of this file. Licensees holding valid TQt
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** Commercial licenses may use this file in accordance with the TQt
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** Commercial License Agreement provided with the Software.
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**
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** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
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** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
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** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted
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** herein.
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**
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**********************************************************************/
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#include "ntqdeepcopy.h"
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/*!
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\class TQDeepCopy ntqdeepcopy.h
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\brief The TQDeepCopy class is a template class which ensures that
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implicitly shared and explicitly shared classes reference unique
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data.
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\reentrant
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\ingroup tools
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\ingroup shared
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Normally, shared copies reference the same data to optimize memory
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use and for maximum speed. In the example below, \c s1, \c s2, \c
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s3, \c s4 and \c s5 share data.
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\code
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// all 5 strings share the same data
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TQString s1 = "abcd";
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TQString s2 = s1;
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TQString s3 = s2;
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TQString s4 = s3;
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TQString s5 = s2;
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\endcode
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TQDeepCopy can be used several ways to ensure that an object
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references unique, unshared data. In the example below, \c s1, \c
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s2 and \c s5 share data, while neither \c s3 nor \c s4 share data.
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\code
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// s1, s2 and s5 share the same data, neither s3 nor s4 are shared
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TQString s1 = "abcd";
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TQString s2 = s1;
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TQDeepCopy<TQString> s3 = s2; // s3 is a deep copy of s2
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TQString s4 = s3; // s4 is a deep copy of s3
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TQString s5 = s2;
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\endcode
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In the example below, \c s1, \c s2 and \c s5 share data, and \c s3
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and \c s4 share data.
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\code
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// s1, s2 and s5 share the same data, s3 and s4 share the same data
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TQString s1 = "abcd";
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TQString s2 = s1;
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TQString s3 = TQDeepCopy<TQString>( s2 ); // s3 is a deep copy of s2
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TQString s4 = s3; // s4 is a shallow copy of s3
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TQString s5 = s2;
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\endcode
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TQDeepCopy can also provide safety in multithreaded applications
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that use shared classes. In the example below, the variable \c
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global_string is used safely since the data contained in \c
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global_string is always a deep copy. This ensures that all threads
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get a unique copy of the data, and that any assignments to \c
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global_string will result in a deep copy.
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\code
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TQDeepCopy<TQString> global_string; // global string data
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TQMutex global_mutex; // mutex to protext global_string
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...
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void setGlobalString( const TQString &str )
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{
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global_mutex.lock();
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global_string = str; // global_string is a deep copy of str
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global_mutex.unlock();
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}
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...
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void MyThread::run()
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{
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global_mutex.lock();
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TQString str = global_string; // str is a deep copy of global_string
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global_mutex.unlock();
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// process the string data
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...
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// update global_string
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setGlobalString( str );
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}
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\endcode
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\warning It is the application developer's responsibility to
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protect the object shared across multiple threads.
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The examples above use TQString, which is an implicitly shared
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class. The behavior of TQDeepCopy is the same when using explicitly
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shared classes like TQByteArray.
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Currently, TQDeepCopy works with the following classes:
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\list
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\i TQMemArray (including subclasses like TQByteArray and TQCString)
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\i TQMap
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\i TQString
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\i TQValueList (including subclasses like TQStringList and TQValueStack)
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\i TQValueVector
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\endlist
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\sa \link threads.html Thread Support in TQt \endlink
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*/
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/*!
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\fn TQDeepCopy::TQDeepCopy()
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Constructs an empty instance of type \e T.
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*/
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/*!
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\fn TQDeepCopy::TQDeepCopy( const T &t )
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Constructs a deep copy of \a t.
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*/
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/*!
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\fn TQDeepCopy<T>& TQDeepCopy::operator=( const T &t )
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Assigns a deep copy of \a t.
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*/
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/*!
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\fn TQDeepCopy::operator T ()
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Returns a deep copy of the encapsulated data.
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*/
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