| 1 | /****************************************************************************
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| 2 | **
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| 3 | ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
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| 4 | ** All rights reserved.
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| 5 | ** Contact: Nokia Corporation ([email protected])
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| 6 | **
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| 7 | ** This file is part of the Qt3Support module of the Qt Toolkit.
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| 8 | **
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| 9 | ** $QT_BEGIN_LICENSE:LGPL$
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| 10 | ** Commercial Usage
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| 11 | ** Licensees holding valid Qt Commercial licenses may use this file in
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| 12 | ** accordance with the Qt Commercial License Agreement provided with the
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| 13 | ** Software or, alternatively, in accordance with the terms contained in
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| 14 | ** a written agreement between you and Nokia.
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| 15 | **
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| 16 | ** GNU Lesser General Public License Usage
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| 17 | ** Alternatively, this file may be used under the terms of the GNU Lesser
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| 18 | ** General Public License version 2.1 as published by the Free Software
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| 19 | ** Foundation and appearing in the file LICENSE.LGPL included in the
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| 23 | **
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| 24 | ** In addition, as a special exception, Nokia gives you certain additional
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| 25 | ** rights. These rights are described in the Nokia Qt LGPL Exception
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| 26 | ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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| 27 | **
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| 28 | ** GNU General Public License Usage
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| 29 | ** Alternatively, this file may be used under the terms of the GNU
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| 30 | ** General Public License version 3.0 as published by the Free Software
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| 31 | ** Foundation and appearing in the file LICENSE.GPL included in the
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| 35 | **
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| 36 | ** If you have questions regarding the use of this file, please contact
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| 37 | ** Nokia at [email protected].
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| 38 | ** $QT_END_LICENSE$
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| 39 | **
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| 40 | ****************************************************************************/
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| 41 |
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| 42 | #include "q3deepcopy.h"
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| 43 |
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| 44 | QT_BEGIN_NAMESPACE
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| 45 |
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| 46 | /*!
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| 47 | \class Q3DeepCopy
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| 48 | \brief The Q3DeepCopy class is a template class which ensures that
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| 49 | implicitly shared and explicitly shared classes reference unique
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| 50 | data.
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| 51 |
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| 52 | \reentrant
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| 53 |
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| 54 | \compat
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| 55 |
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| 56 | Normally, shared copies reference the same data to optimize memory
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| 57 | use and for maximum speed. In the example below, \c s1, \c s2, \c
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| 58 | s3, \c s4 and \c s5 share data.
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| 59 |
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| 60 | \snippet doc/src/snippets/code/src_qt3support_tools_q3deepcopy.cpp 0
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| 61 |
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| 62 | Q3DeepCopy can be used several ways to ensure that an object
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| 63 | references unique, unshared data. In the example below, \c s1, \c
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| 64 | s2 and \c s5 share data, while neither \c s3 nor \c s4 share data.
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| 65 | \snippet doc/src/snippets/code/src_qt3support_tools_q3deepcopy.cpp 1
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| 66 |
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| 67 | In the example below, \c s1, \c s2 and \c s5 share data, and \c s3
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| 68 | and \c s4 share data.
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| 69 | \snippet doc/src/snippets/code/src_qt3support_tools_q3deepcopy.cpp 2
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| 70 |
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| 71 | Q3DeepCopy can also provide safety in multithreaded applications
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| 72 | that use shared classes. In the example below, the variable \c
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| 73 | global_string is used safely since the data contained in \c
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| 74 | global_string is always a deep copy. This ensures that all threads
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| 75 | get a unique copy of the data, and that any assignments to \c
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| 76 | global_string will result in a deep copy.
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| 77 |
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| 78 | \snippet doc/src/snippets/code/src_qt3support_tools_q3deepcopy.cpp 3
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| 79 |
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| 80 | \warning It is the application developer's responsibility to
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| 81 | protect the object shared across multiple threads.
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| 82 |
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| 83 | The examples above use QString, which is an implicitly shared
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| 84 | class. The behavior of Q3DeepCopy is the same when using explicitly
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| 85 | shared classes like QByteArray.
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| 86 |
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| 87 | Currently, Q3DeepCopy works with the following classes:
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| 88 | \list
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| 89 | \i QMemArray (including subclasses like QByteArray and QCString)
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| 90 | \i QMap
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| 91 | \i QString
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| 92 | \i QValueList (including subclasses like QStringList and QValueStack)
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| 93 | \i QValueVector
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| 94 | \endlist
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| 95 |
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| 96 | \sa \link threads.html Thread Support in Qt \endlink
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| 97 | */
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| 98 |
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| 99 | /*!
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| 100 | \fn Q3DeepCopy::Q3DeepCopy()
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| 101 |
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| 102 | Constructs an empty instance of type \e T.
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| 103 | */
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| 104 |
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| 105 | /*!
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| 106 | \fn Q3DeepCopy::Q3DeepCopy( const T &t )
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| 107 |
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| 108 | Constructs a deep copy of \a t.
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| 109 | */
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| 110 |
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| 111 | /*!
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| 112 | \fn Q3DeepCopy<T>& Q3DeepCopy::operator=( const T &t )
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| 113 |
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| 114 | Assigns a deep copy of \a t.
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| 115 | */
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| 116 |
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| 117 | /*!
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| 118 | \fn Q3DeepCopy::operator T ()
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| 119 |
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| 120 | Returns a deep copy of the encapsulated data.
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| 121 | */
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| 122 |
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| 123 | QT_END_NAMESPACE
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