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authorQt by Nokia <qt-info@nokia.com>2011-04-27 12:05:43 +0200
committeraxis <qt-info@nokia.com>2011-04-27 12:05:43 +0200
commite1b2c9deb5943faae2b29be6a5c006f75bb73f06 (patch)
treefc79e45367c0a8fc71185e9afc33f7503a58653c /src/xmlpatterns/expr/qunaryexpression_p.h
downloadqtxmlpatterns-e1b2c9deb5943faae2b29be6a5c006f75bb73f06.tar.gz
Initial import from the monolithic Qt.
This is the beginning of revision history for this module. If you want to look at revision history older than this, please refer to the Qt Git wiki for how to use Git history grafting. At the time of writing, this wiki is located here: http://qt.gitorious.org/qt/pages/GitIntroductionWithQt If you have already performed the grafting and you don't see any history beyond this commit, try running "git log" with the "--follow" argument. Branched from the monolithic repo, Qt master branch, at commit 896db169ea224deb96c59ce8af800d019de63f12
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+/****************************************************************************
+**
+** Copyright (C) 2011 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_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 <frans.englich@nokia.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