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1 | /**************************************************************************** | ||
2 | ** $Id$ | ||
3 | ** | ||
4 | ** Implementation of QDeepCopy class | ||
5 | ** | ||
6 | ** Created : 20020613 | ||
7 | ** | ||
8 | ** Copyright (C) 1992-2002 Trolltech AS. All rights reserved. | ||
9 | ** | ||
10 | ** This file is part of the kernel module of the Qt GUI Toolkit. | ||
11 | ** | ||
12 | ** This file may be distributed under the terms of the Q Public License | ||
13 | ** as defined by Trolltech AS of Norway and appearing in the file | ||
14 | ** LICENSE.QPL included in the packaging of this file. | ||
15 | ** | ||
16 | ** This file may be distributed and/or modified under the terms of the | ||
17 | ** GNU General Public License version 2 as published by the Free Software | ||
18 | ** Foundation and appearing in the file LICENSE.GPL included in the | ||
19 | ** packaging of this file. | ||
20 | ** | ||
21 | ** Licensees holding valid Qt Enterprise Edition or Qt Professional Edition | ||
22 | ** licenses may use this file in accordance with the Qt Commercial License | ||
23 | ** Agreement provided with the Software. | ||
24 | ** | ||
25 | ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE | ||
26 | ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. | ||
27 | ** | ||
28 | ** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for | ||
29 | ** information about Qt Commercial License Agreements. | ||
30 | ** See http://www.trolltech.com/qpl/ for QPL licensing information. | ||
31 | ** See http://www.trolltech.com/gpl/ for GPL licensing information. | ||
32 | ** | ||
33 | ** Contact info@trolltech.com if any conditions of this licensing are | ||
34 | ** not clear to you. | ||
35 | ** | ||
36 | **********************************************************************/ | ||
37 | |||
38 | #include "qdeepcopy.h" | ||
39 | |||
40 | /*! | ||
41 | \class QDeepCopy qdeepcopy.h | ||
42 | \brief The QDeepCopy class is a template class which ensures that | ||
43 | implicitly shared and explicitly shared classes reference unique | ||
44 | data. | ||
45 | |||
46 | \reentrant | ||
47 | |||
48 | \ingroup tools | ||
49 | \ingroup shared | ||
50 | |||
51 | Normally, shared copies reference the same data to optimize memory | ||
52 | use and for maximum speed. In the example below, \c s1, \c s2, \c | ||
53 | s3, \c s4 and \c s5 share data. | ||
54 | |||
55 | \code | ||
56 | // all 5 strings share the same data | ||
57 | QString s1 = "abcd"; | ||
58 | QString s2 = s1; | ||
59 | QString s3 = s2; | ||
60 | QString s4 = s3; | ||
61 | QString s5 = s2; | ||
62 | \endcode | ||
63 | |||
64 | QDeepCopy can be used several ways to ensure that an object | ||
65 | references unique, unshared data. In the example below, \c s1, \c | ||
66 | s2 and \c s5 share data, while neither \c s3 nor \c s4 share data. | ||
67 | \code | ||
68 | // s1, s2 and s5 share the same data, neither s3 nor s4 are shared | ||
69 | QString s1 = "abcd"; | ||
70 | QString s2 = s1; | ||
71 | QDeepCopy<QString> s3 = s2; // s3 is a deep copy of s2 | ||
72 | QString s4 = s3; // s4 is a deep copy of s3 | ||
73 | QString s5 = s2; | ||
74 | \endcode | ||
75 | |||
76 | In the example below, \c s1, \c s2 and \c s5 share data, and \c s3 | ||
77 | and \c s4 share data. | ||
78 | \code | ||
79 | // s1, s2 and s5 share the same data, s3 and s4 share the same data | ||
80 | QString s1 = "abcd"; | ||
81 | QString s2 = s1; | ||
82 | QString s3 = QDeepCopy<QString>( s2 ); // s3 is a deep copy of s2 | ||
83 | QString s4 = s3; // s4 is a shallow copy of s3 | ||
84 | QString s5 = s2; | ||
85 | \endcode | ||
86 | |||
87 | QDeepCopy can also provide safety in multithreaded applications | ||
88 | that use shared classes. In the example below, the variable \c | ||
89 | global_string is used safely since the data contained in \c | ||
90 | global_string is always a deep copy. This ensures that all threads | ||
91 | get a unique copy of the data, and that any assignments to \c | ||
92 | global_string will result in a deep copy. | ||
93 | |||
94 | \code | ||
95 | QDeepCopy<QString> global_string; // global string data | ||
96 | QMutex global_mutex; // mutex to protext global_string | ||
97 | |||
98 | ... | ||
99 | |||
100 | void setGlobalString( const QString &str ) | ||
101 | { | ||
102 | global_mutex.lock(); | ||
103 | global_string = str; // global_string is a deep copy of str | ||
104 | global_mutex.unlock(); | ||
105 | } | ||
106 | |||
107 | ... | ||
108 | |||
109 | void MyThread::run() | ||
110 | { | ||
111 | global_mutex.lock(); | ||
112 | QString str = global_string; // str is a deep copy of global_string | ||
113 | global_mutex.unlock(); | ||
114 | |||
115 | // process the string data | ||
116 | ... | ||
117 | |||
118 | // update global_string | ||
119 | setGlobalString( str ); | ||
120 | } | ||
121 | \endcode | ||
122 | |||
123 | \warning It is the application developer's responsibility to | ||
124 | protect the object shared across multiple threads. | ||
125 | |||
126 | The examples above use QString, which is an implicitly shared | ||
127 | class. The behavior of QDeepCopy is the same when using explicitly | ||
128 | shared classes like QByteArray. | ||
129 | |||
130 | Currently, QDeepCopy works with the following classes: | ||
131 | \list | ||
132 | \i QMemArray (including subclasses like QByteArray and QCString) | ||
133 | \i QMap | ||
134 | \i QString | ||
135 | \i QValueList (including subclasses like QStringList and QValueStack) | ||
136 | \i QValueVector | ||
137 | \endlist | ||
138 | |||
139 | \sa \link threads.html Thread Support in Qt \endlink | ||
140 | */ | ||
141 | |||
142 | /*! | ||
143 | \fn QDeepCopy::QDeepCopy() | ||
144 | |||
145 | Constructs an empty instance of type \e T. | ||
146 | */ | ||
147 | |||
148 | /*! | ||
149 | \fn QDeepCopy::QDeepCopy( const T &t ) | ||
150 | |||
151 | Constructs a deep copy of \a t. | ||
152 | */ | ||
153 | |||
154 | /*! | ||
155 | \fn QDeepCopy<T>& QDeepCopy::operator=( const T &t ) | ||
156 | |||
157 | Assigns a deep copy of \a t. | ||
158 | */ | ||
159 | |||
160 | /*! | ||
161 | \fn QDeepCopy::operator T () | ||
162 | |||
163 | Returns a deep copy of the encapsulated data. | ||
164 | */ | ||
165 | |||