Add non-threadsafe QGuard class

Cherry pick of 4031c0f0613090d70cd1fcacfc5b8316b12eb14e

Reviewed-by: Andreas

1 files changed, 151 insertions, 0 deletions

diff --git a/src/corelib/kernel/qguard_p.h b/src/corelib/kernel/qguard_p.h
new file mode 100644
index 0000000..7236ed6
--- /dev/null
+++ b/src/corelib/kernel/qguard_p.h
@@ -0,0 +1,151 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at http://www.qtsoftware.com/contact.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QGUARD_P_H
+#define QGUARD_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of qapplication_*.cpp, qwidget*.cpp and qfiledialog.cpp.  This header
+// file may change from version to version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include "QtCore/qglobal.h"
+
+QT_BEGIN_NAMESPACE
+
+class QObject;
+template<class T>
+class QGuard
+{
+    QObject *o;
+    QGuard<QObject> *next;
+    QGuard<QObject> **prev;
+    friend void q_guard_addGuard(QGuard<QObject> *);
+    friend void q_guard_removeGuard(QGuard<QObject> *);
+    friend class QObjectPrivate;
+public:
+    inline QGuard();
+    inline QGuard(T *);
+    inline QGuard(const QGuard<T> &);
+    inline virtual ~QGuard();
+
+    inline QGuard<T> &operator=(const QGuard<T> &o);
+    inline QGuard<T> &operator=(T *);
+    
+    inline bool isNull() const
+        { return !o; }
+
+    inline T* operator->() const
+        { return static_cast<T*>(const_cast<QObject*>(o)); }
+    inline T& operator*() const
+        { return *static_cast<T*>(const_cast<QObject*>(o)); }
+    inline operator T*() const
+        { return static_cast<T*>(const_cast<QObject*>(o)); }
+    inline T* data() const
+        { return static_cast<T*>(const_cast<QObject*>(o)); }
+
+protected:
+    virtual void objectDestroyed(T *) {}
+};
+
+void Q_CORE_EXPORT q_guard_addGuard(QGuard<QObject> *);
+void Q_CORE_EXPORT q_guard_removeGuard(QGuard<QObject> *);
+
+template<class T>
+QGuard<T>::QGuard()
+: o(0), next(0), prev(0)
+{
+}
+
+template<class T>
+QGuard<T>::QGuard(T *g)
+: o(g), next(0), prev(0)
+{
+    if (o) q_guard_addGuard(reinterpret_cast<QGuard<QObject> *>(this));
+}
+
+template<class T>
+QGuard<T>::QGuard(const QGuard<T> &g)
+: o(g.o), next(0), prev(0)
+{
+    if (o) q_guard_addGuard(reinterpret_cast<QGuard<QObject> *>(this));
+}
+
+template<class T>
+QGuard<T>::~QGuard()
+{
+    if (prev) q_guard_removeGuard(reinterpret_cast<QGuard<QObject> *>(this));
+    o = 0;
+}
+
+template<class T>
+QGuard<T> &QGuard<T>::operator=(const QGuard<T> &g)
+{
+    if (g.o != o) {
+        if (prev) 
+            q_guard_removeGuard(reinterpret_cast<QGuard<QObject> *>(this));
+        o = g.o;
+        if (o) q_guard_addGuard(reinterpret_cast<QGuard<QObject> *>(this));
+    }
+    return *this;
+}
+
+template<class T>
+inline QGuard<T> &QGuard<T>::operator=(T *g)
+{
+    if (g != o) {
+        if (prev) 
+            q_guard_removeGuard(reinterpret_cast<QGuard<QObject> *>(this));
+        o = g;
+        if (o) q_guard_addGuard(reinterpret_cast<QGuard<QObject> *>(this));
+    }
+    return *this;
+}
+
+QT_END_NAMESPACE
+
+#endif // QGUARD_P_H