src/declarative/qml/qdeclarativeguard_p.h
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     1 /****************************************************************************
       
     2 **
       
     3 ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
       
     4 ** All rights reserved.
       
     5 ** Contact: Nokia Corporation (qt-info@nokia.com)
       
     6 **
       
     7 ** This file is part of the QtCore module of the Qt Toolkit.
       
     8 **
       
     9 ** $QT_BEGIN_LICENSE:LGPL$
       
    10 ** No Commercial Usage
       
    11 ** This file contains pre-release code and may not be distributed.
       
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    13 ** contained in the Technology Preview License Agreement accompanying
       
    14 ** this package.
       
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    16 ** GNU Lesser General Public License Usage
       
    17 ** Alternatively, this file may be used under the terms of the GNU Lesser
       
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    19 ** Foundation and appearing in the file LICENSE.LGPL included in the
       
    20 ** packaging of this file.  Please review the following information to
       
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    24 ** In addition, as a special exception, Nokia gives you certain additional
       
    25 ** rights.  These rights are described in the Nokia Qt LGPL Exception
       
    26 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
       
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    28 ** If you have questions regarding the use of this file, please contact
       
    29 ** Nokia at qt-info@nokia.com.
       
    30 **
       
    31 **
       
    32 **
       
    33 **
       
    34 **
       
    35 **
       
    36 **
       
    37 **
       
    38 ** $QT_END_LICENSE$
       
    39 **
       
    40 ****************************************************************************/
       
    41 
       
    42 #ifndef QDECLARATIVEGUARD_P_H
       
    43 #define QDECLARATIVEGUARD_P_H
       
    44 
       
    45 //
       
    46 //  W A R N I N G
       
    47 //  -------------
       
    48 //
       
    49 // This file is not part of the Qt API.  It exists for the convenience
       
    50 // of qapplication_*.cpp, qwidget*.cpp and qfiledialog.cpp.  This header
       
    51 // file may change from version to version without notice, or even be removed.
       
    52 //
       
    53 // We mean it.
       
    54 //
       
    55 
       
    56 #include <QtCore/qglobal.h>
       
    57 #include <QtCore/qvariant.h>
       
    58 
       
    59 QT_BEGIN_NAMESPACE
       
    60 
       
    61 class QObject;
       
    62 template<class T>
       
    63 class QDeclarativeGuard
       
    64 {
       
    65     QObject *o;
       
    66     QDeclarativeGuard<QObject> *next;
       
    67     QDeclarativeGuard<QObject> **prev;
       
    68     friend class QDeclarativeData;
       
    69 public:
       
    70     inline QDeclarativeGuard();
       
    71     inline QDeclarativeGuard(T *);
       
    72     inline QDeclarativeGuard(const QDeclarativeGuard<T> &);
       
    73     inline virtual ~QDeclarativeGuard();
       
    74 
       
    75     inline QDeclarativeGuard<T> &operator=(const QDeclarativeGuard<T> &o);
       
    76     inline QDeclarativeGuard<T> &operator=(T *);
       
    77     
       
    78     inline bool isNull() const
       
    79         { return !o; }
       
    80 
       
    81     inline T* operator->() const
       
    82         { return static_cast<T*>(const_cast<QObject*>(o)); }
       
    83     inline T& operator*() const
       
    84         { return *static_cast<T*>(const_cast<QObject*>(o)); }
       
    85     inline operator T*() const
       
    86         { return static_cast<T*>(const_cast<QObject*>(o)); }
       
    87     inline T* data() const
       
    88         { return static_cast<T*>(const_cast<QObject*>(o)); }
       
    89 
       
    90 protected:
       
    91     virtual void objectDestroyed(T *) {}
       
    92 
       
    93 private:
       
    94     inline void addGuard();
       
    95     inline void remGuard();
       
    96 };
       
    97 
       
    98 QT_END_NAMESPACE
       
    99 
       
   100 Q_DECLARE_METATYPE(QDeclarativeGuard<QObject>)
       
   101 
       
   102 #include "private/qdeclarativedata_p.h"
       
   103 
       
   104 QT_BEGIN_NAMESPACE
       
   105 
       
   106 template<class T>
       
   107 QDeclarativeGuard<T>::QDeclarativeGuard()
       
   108 : o(0), next(0), prev(0)
       
   109 {
       
   110 }
       
   111 
       
   112 template<class T>
       
   113 QDeclarativeGuard<T>::QDeclarativeGuard(T *g)
       
   114 : o(g), next(0), prev(0)
       
   115 {
       
   116     if (o) addGuard();
       
   117 }
       
   118 
       
   119 template<class T>
       
   120 QDeclarativeGuard<T>::QDeclarativeGuard(const QDeclarativeGuard<T> &g)
       
   121 : o(g.o), next(0), prev(0)
       
   122 {
       
   123     if (o) addGuard();
       
   124 }
       
   125 
       
   126 template<class T>
       
   127 QDeclarativeGuard<T>::~QDeclarativeGuard()
       
   128 {
       
   129     if (prev) remGuard();
       
   130     o = 0;
       
   131 }
       
   132 
       
   133 template<class T>
       
   134 QDeclarativeGuard<T> &QDeclarativeGuard<T>::operator=(const QDeclarativeGuard<T> &g)
       
   135 {
       
   136     if (g.o != o) {
       
   137         if (prev) remGuard();
       
   138         o = g.o;
       
   139         if (o) addGuard();
       
   140     }
       
   141     return *this;
       
   142 }
       
   143 
       
   144 template<class T>
       
   145 QDeclarativeGuard<T> &QDeclarativeGuard<T>::operator=(T *g)
       
   146 {
       
   147     if (g != o) {
       
   148         if (prev) remGuard();
       
   149         o = g;
       
   150         if (o) addGuard();
       
   151     }
       
   152     return *this;
       
   153 }
       
   154 
       
   155 QT_END_NAMESPACE
       
   156 
       
   157 #endif // QDECLARATIVEGUARD_P_H