Line data    Source code

       1             : /****************************************************************************
       2             : **
       3             : ** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
       4             : ** Contact: http://www.qt-project.org/legal
       5             : **
       6             : ** This file is part of the QtCore module of the Qt Toolkit.
       7             : **
       8             : ** $QT_BEGIN_LICENSE:LGPL$
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      17             : ** GNU Lesser General Public License Usage
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      23             : ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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      25             : ** In addition, as a special exception, Digia gives you certain additional
      26             : ** rights.  These rights are described in the Digia Qt LGPL Exception
      27             : ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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      29             : ** GNU General Public License Usage
      30             : ** Alternatively, this file may be used under the terms of the GNU
      31             : ** General Public License version 3.0 as published by the Free Software
      32             : ** Foundation and appearing in the file LICENSE.GPL included in the
      33             : ** packaging of this file.  Please review the following information to
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      40             : ****************************************************************************/
      41             : 
      42             : #ifndef QREFCOUNT_H
      43             : #define QREFCOUNT_H
      44             : 
      45             : #include <QtCore/qatomic.h>
      46             : 
      47             : QT_BEGIN_NAMESPACE
      48             : 
      49             : 
      50             : namespace QtPrivate
      51             : {
      52             : 
      53             : class RefCount
      54             : {
      55             : public:
      56         177 :     inline bool ref() Q_DECL_NOTHROW {
      57         177 :         int count = atomic.load();
      58             : #if QT_SUPPORTS(UNSHARABLE_CONTAINERS)
      59         177 :         if (count == 0) // !isSharable
      60           0 :             return false;
      61             : #endif
      62         177 :         if (count != -1) // !isStatic
      63         132 :             atomic.ref();
      64         177 :         return true;
      65             :     }
      66             : 
      67         743 :     inline bool deref() Q_DECL_NOTHROW {
      68         743 :         int count = atomic.load();
      69             : #if QT_SUPPORTS(UNSHARABLE_CONTAINERS)
      70         743 :         if (count == 0) // !isSharable
      71           0 :             return false;
      72             : #endif
      73         743 :         if (count == -1) // isStatic
      74         394 :             return true;
      75         349 :         return atomic.deref();
      76             :     }
      77             : 
      78             : #if QT_SUPPORTS(UNSHARABLE_CONTAINERS)
      79             :     bool setSharable(bool sharable) Q_DECL_NOTHROW
      80             :     {
      81             :         Q_ASSERT(!isShared());
      82             :         if (sharable)
      83             :             return atomic.testAndSetRelaxed(0, 1);
      84             :         else
      85             :             return atomic.testAndSetRelaxed(1, 0);
      86             :     }
      87             : 
      88           0 :     bool isSharable() const Q_DECL_NOTHROW
      89             :     {
      90             :         // Sharable === Shared ownership.
      91           0 :         return atomic.load() != 0;
      92             :     }
      93             : #endif
      94             : 
      95          47 :     bool isStatic() const Q_DECL_NOTHROW
      96             :     {
      97             :         // Persistent object, never deleted
      98          47 :         return atomic.load() == -1;
      99             :     }
     100             : 
     101         203 :     bool isShared() const Q_DECL_NOTHROW
     102             :     {
     103         203 :         int count = atomic.load();
     104         203 :         return (count != 1) && (count != 0);
     105             :     }
     106             : 
     107             :     void initializeOwned() Q_DECL_NOTHROW { atomic.store(1); }
     108             :     void initializeUnsharable() Q_DECL_NOTHROW { atomic.store(0); }
     109             : 
     110             :     QBasicAtomicInt atomic;
     111             : };
     112             : 
     113             : }
     114             : 
     115             : #define Q_REFCOUNT_INITIALIZE_STATIC { Q_BASIC_ATOMIC_INITIALIZER(-1) }
     116             : 
     117             : QT_END_NAMESPACE
     118             : 
     119             : #endif