Long live Qt 4.5!

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+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (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 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 qt-sales@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_UnaryExpression_H
+#define Patternist_UnaryExpression_H
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+#include "qarithmeticexpression_p.h"
+
+namespace QPatternist
+{
+    /**
+     * @short Implements XPath 2.0 unary expression, <tt>(-|+)ValueExpr</tt>.
+     *
+     * UnaryExpression is implemented by rewriting the expression <tt>operator [expr]</tt>
+     * to the ArithmeticExpression <tt>0 operator [expr]</tt>. For example, the expression
+     * <tt>+3</tt> becomes <tt>0 + 3</tt>, and <tt>-nodetest</tt> becomes <tt>0 - nodetest</tt>.
+     *
+     * On top of that expression ArithmeticExpression does the usual type
+     * checking conversion. The only thing this class do, is to overide
+     * evaluateSingleton() and calls Numeric::toNegated(). The reason this
+     * UnaryExpression is needed at all and that <tt>0 - [expr]</tt> is
+     * insufficent is that <tt>0 - xs:double(0)</tt> needs to return -0,
+     * instead of 0. I know no other difference.
+     *
+     * In most cases the constant propagation optimization rewrites UnaryExpression into
+     * a value, an instance of a sub-class of the Numeric class, wrapped with
+     * Literal.
+     *
+     * Beyond the mathematical implication the unary expression have, it also
+     * have the significant effect that it may invoke type promotion or that an expression
+     * may contain a type error. For example, the expression "+'a string'" contains a type error, since
+     * no unary operator is defined for @c xs:string. This is the reason why the '+' unary
+     * operator isn't ignored.
+     *
+     * @see <a href="http://www.w3.org/TR/xpath20/#id-arithmetic">XML Path Language
+     * (XPath) 2.0, 3.4 Arithmetic Expressions</a>
+     * @see <a href="http://www.w3.org/TR/xpath-functions/#func-numeric-unary-plus">XQuery 1.0 and XPath
+     * 2.0 Functions and Operators, 6.2.7 op:numeric-unary-plus</a>
+     * @see <a href="http://www.w3.org/TR/xpath-functions/#func-numeric-unary-minus">XQuery 1.0 and XPath
+     * 2.0 Functions and Operators, 6.2.8 op:numeric-unary-minus</a>
+     * @author Frans Englich <fenglich@trolltech.com>
+     * @ingroup Patternist_expressions
+     */
+    class UnaryExpression : public ArithmeticExpression
+    {
+    public:
+        UnaryExpression(const AtomicMathematician::Operator op,
+                        const Expression::Ptr &operand,
+                        const StaticContext::Ptr &context);
+
+        virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;
+
+    private:
+        Q_DISABLE_COPY(UnaryExpression)
+    };
+}
+
+QT_END_NAMESPACE
+
+QT_END_HEADER
+
+#endif