Add non-threadsafe QGuard class

Cherry pick of 4031c0f0613090d70cd1fcacfc5b8316b12eb14e

Reviewed-by: Andreas

5 files changed, 200 insertions, 3 deletions

diff --git a/src/corelib/kernel/kernel.pri b/src/corelib/kernel/kernel.pri
index 7177293..d30f294 100644
--- a/src/corelib/kernel/kernel.pri
+++ b/src/corelib/kernel/kernel.pri
@@ -32,7 +32,8 @@ HEADERS += \
         kernel/qsharedmemory_p.h \
         kernel/qsystemsemaphore.h \
         kernel/qsystemsemaphore_p.h \
-        kernel/qfunctions_p.h
+        kernel/qfunctions_p.h \
+        kernel/qguard_p.h
 
 SOURCES += \
 	kernel/qabstracteventdispatcher.cpp \
@@ -54,7 +55,8 @@ SOURCES += \
         kernel/qcoreglobaldata.cpp \
         kernel/qsharedmemory.cpp \
         kernel/qsystemsemaphore.cpp \
-        kernel/qpointer.cpp
+        kernel/qpointer.cpp \
+        kernel/qguard.cpp
 
 win32 {
 	SOURCES += \
diff --git a/src/corelib/kernel/qguard.cpp b/src/corelib/kernel/qguard.cpp
new file mode 100644
index 0000000..c61be00
--- /dev/null
+++ b/src/corelib/kernel/qguard.cpp
@@ -0,0 +1,26 @@
+#include "qguard_p.h"
+#include <private/qobject_p.h>
+
+void q_guard_addGuard(QGuard<QObject> *g)
+{
+    QObjectPrivate *p = QObjectPrivate::get(g->o);
+    if (p->wasDeleted) {
+        qWarning("QGuard: cannot add guard to deleted object");
+        g->o = 0;
+        return;
+    }
+
+    g->next = p->objectGuards;
+    p->objectGuards = g;
+    g->prev = &p->objectGuards;
+    if (g->next)
+        g->next->prev = &g->next;
+}
+
+void q_guard_removeGuard(QGuard<QObject> *g)
+{
+    *g->prev = g->next;
+    g->next = 0;
+    g->prev = 0;
+}
+
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
diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index e5cc375..a1702d9 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -144,6 +144,7 @@ QObjectPrivate::QObjectPrivate(int version)
     inEventHandler = false;
     inThreadChangeEvent = false;
     deleteWatch = 0;
+    objectGuards = 0;
     hasGuards = false;
 }
 
@@ -426,7 +427,22 @@ void QMetaObject::changeGuard(QObject **ptr, QObject *o)
  */
 void QObjectPrivate::clearGuards(QObject *object)
 {
-    if (!QObjectPrivate::get(object)->hasGuards)
+    QObjectPrivate *priv = QObjectPrivate::get(object);
+    QGuard<QObject> *guard = priv->objectGuards;
+    while (guard) {
+        guard->o = 0;
+        guard = guard->next;
+    }
+    while (priv->objectGuards) {
+        guard = priv->objectGuards;
+        guard->prev = 0;
+        if (guard->next) guard->next->prev = &priv->objectGuards;
+        priv->objectGuards = guard->next;
+        guard->next = 0;
+        guard->objectDestroyed(object);
+    }
+
+    if (!priv->hasGuards)
         return;
     GuardHash *hash = guardHash();
     if (hash) {
diff --git a/src/corelib/kernel/qobject_p.h b/src/corelib/kernel/qobject_p.h
index 6a20040..335768c 100644
--- a/src/corelib/kernel/qobject_p.h
+++ b/src/corelib/kernel/qobject_p.h
@@ -60,6 +60,7 @@
 #include "QtCore/qvector.h"
 #include "QtCore/qreadwritelock.h"
 #include "QtCore/qvariant.h"
+#include "qguard_p.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -174,6 +175,7 @@ public:
     static void resetDeleteWatch(QObjectPrivate *d, int *oldWatch, int deleteWatch);
 
     int *deleteWatch;
+    QGuard<QObject> *objectGuards;
 
     static QObjectPrivate *get(QObject *o) {
         return o->d_func();