--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/xmlpatterns/utils/qcppcastinghelper_p.h Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,161 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtXmlPatterns 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 Technology Preview License Agreement accompanying
+** this package.
+**
+** 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 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+//
+// W A R N I N G
+// -------------
+//
+// This file is not part of the Qt API. It exists purely as an
+// implementation detail. This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+
+#ifndef Patternist_CppCastingHelper_H
+#define Patternist_CppCastingHelper_H
+
+#include <QtCore/QtGlobal>
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+namespace QPatternist
+{
+ /**
+ * @short Provides convenience methods for performing static casts between C++ classes.
+ *
+ * In Patternist, it is very common to do up-casts from Expression or Item, which typically
+ * involves writing messy code. Such an old-way cast looks like this:
+ *
+ * @code
+ * static_cast<const MyClass *>(myInstance.data())->myClassMember()
+ * @endcode
+ *
+ * CppCastingHelper provides the convenience method as() for this, which is functionally
+ * equivalent to the above code, but simpler:
+ *
+ * @code
+ * myInstance->as<MyClass>()->myClassMember()
+ * @endcode
+ *
+ * The as() function performs a static cast.
+ *
+ * By using CppCastingHelper, this is achieved:
+ *
+ * - Const correctness is automatically taken care of
+ * - Less code to write
+ * - When compiling in debug mode, the as() functions uses a @c dynamic_cast to verify that the
+ * static casts are properly done, such that sensible error messages are given when the casts
+ * are invalid. It also traps invalid casts which nevertheless happen to work on a particular
+ * platform/compiler/hardware architecture.
+ *
+ * CppCastingHelper is a template class where the TSubClass parameter must be the class
+ * inheriting CppCastingHelper. See Item or Expression for demonstration.
+ *
+ * @author Frans Englich <frans.englich@nokia.com>
+ */
+ template<typename TSubClass>
+ class CppCastingHelper
+ {
+ public:
+
+ /**
+ * Casts this instance to:
+ *
+ * @code
+ * const TCastTarget *
+ * @endcode
+ *
+ * and returns the result.
+ *
+ * When compiled in debug mode, this function perform a @c dynamic_cast, in order to
+ * check the correctness of the cast.
+ */
+ template<typename TCastTarget>
+ inline const TCastTarget *as() const
+ {
+#if defined(Patternist_DEBUG) && !defined(Q_CC_XLC)
+/* At least on aix-xlc-64, the compiler cries when it sees dynamic_cast. */
+ Q_ASSERT_X(dynamic_cast<const TCastTarget *>(static_cast<const TSubClass *>(this)),
+ Q_FUNC_INFO,
+ "The cast is invalid. This class does not inherit the cast target.");
+#endif
+ return static_cast<const TCastTarget *>(static_cast<const TSubClass *>(this));
+ }
+
+ /**
+ * Casts this instance to:
+ *
+ * @code
+ * TCastTarget *
+ * @endcode
+ *
+ * and returns the result.
+ *
+ * When compiled in debug mode, a @c dynamic_cast is attempted, in order to
+ * check the correctness of the cast.
+ */
+ template<typename TCastTarget>
+ inline TCastTarget *as()
+ {
+#if defined(Patternist_DEBUG) && !defined(Q_CC_XLC)
+/* At least on aix-xlc-64, the compiler cries when it sees dynamic_cast. */
+ Q_ASSERT_X(dynamic_cast<TCastTarget *>(static_cast<TSubClass *>(this)),
+ Q_FUNC_INFO,
+ "The cast is invalid. This class does not inherit the cast target.");
+#endif
+ return static_cast<TCastTarget *>(static_cast<TSubClass *>(this));
+ }
+
+ protected:
+ /**
+ * This constructor is protected because this class must be sub-classed.
+ */
+ inline CppCastingHelper() {}
+ };
+}
+
+QT_END_NAMESPACE
+
+QT_END_HEADER
+
+#endif