|
1 /**************************************************************************** |
|
2 ** |
|
3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). |
|
4 ** All rights reserved. |
|
5 ** Contact: Nokia Corporation (qt-info@nokia.com) |
|
6 ** |
|
7 ** This file is part of the QtXmlPatterns module of the Qt Toolkit. |
|
8 ** |
|
9 ** $QT_BEGIN_LICENSE:LGPL$ |
|
10 ** No Commercial Usage |
|
11 ** This file contains pre-release code and may not be distributed. |
|
12 ** You may use this file in accordance with the terms and conditions |
|
13 ** contained in the Technology Preview License Agreement accompanying |
|
14 ** this package. |
|
15 ** |
|
16 ** GNU Lesser General Public License Usage |
|
17 ** Alternatively, this file may be used under the terms of the GNU Lesser |
|
18 ** General Public License version 2.1 as published by the Free Software |
|
19 ** Foundation and appearing in the file LICENSE.LGPL included in the |
|
20 ** packaging of this file. Please review the following information to |
|
21 ** ensure the GNU Lesser General Public License version 2.1 requirements |
|
22 ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. |
|
23 ** |
|
24 ** In addition, as a special exception, Nokia gives you certain additional |
|
25 ** rights. These rights are described in the Nokia Qt LGPL Exception |
|
26 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. |
|
27 ** |
|
28 ** If you have questions regarding the use of this file, please contact |
|
29 ** Nokia at qt-info@nokia.com. |
|
30 ** |
|
31 ** |
|
32 ** |
|
33 ** |
|
34 ** |
|
35 ** |
|
36 ** |
|
37 ** |
|
38 ** $QT_END_LICENSE$ |
|
39 ** |
|
40 ****************************************************************************/ |
|
41 |
|
42 // |
|
43 // W A R N I N G |
|
44 // ------------- |
|
45 // |
|
46 // This file is not part of the Qt API. It exists purely as an |
|
47 // implementation detail. This header file may change from version to |
|
48 // version without notice, or even be removed. |
|
49 // |
|
50 // We mean it. |
|
51 |
|
52 #ifndef Patternist_UnaryExpression_H |
|
53 #define Patternist_UnaryExpression_H |
|
54 |
|
55 QT_BEGIN_HEADER |
|
56 |
|
57 QT_BEGIN_NAMESPACE |
|
58 |
|
59 #include "qarithmeticexpression_p.h" |
|
60 |
|
61 namespace QPatternist |
|
62 { |
|
63 /** |
|
64 * @short Implements XPath 2.0 unary expression, <tt>(-|+)ValueExpr</tt>. |
|
65 * |
|
66 * UnaryExpression is implemented by rewriting the expression <tt>operator [expr]</tt> |
|
67 * to the ArithmeticExpression <tt>0 operator [expr]</tt>. For example, the expression |
|
68 * <tt>+3</tt> becomes <tt>0 + 3</tt>, and <tt>-nodetest</tt> becomes <tt>0 - nodetest</tt>. |
|
69 * |
|
70 * On top of that expression ArithmeticExpression does the usual type |
|
71 * checking conversion. The only thing this class do, is to overide |
|
72 * evaluateSingleton() and calls Numeric::toNegated(). The reason this |
|
73 * UnaryExpression is needed at all and that <tt>0 - [expr]</tt> is |
|
74 * insufficent is that <tt>0 - xs:double(0)</tt> needs to return -0, |
|
75 * instead of 0. I know no other difference. |
|
76 * |
|
77 * In most cases the constant propagation optimization rewrites UnaryExpression into |
|
78 * a value, an instance of a sub-class of the Numeric class, wrapped with |
|
79 * Literal. |
|
80 * |
|
81 * Beyond the mathematical implication the unary expression have, it also |
|
82 * have the significant effect that it may invoke type promotion or that an expression |
|
83 * may contain a type error. For example, the expression "+'a string'" contains a type error, since |
|
84 * no unary operator is defined for @c xs:string. This is the reason why the '+' unary |
|
85 * operator isn't ignored. |
|
86 * |
|
87 * @see <a href="http://www.w3.org/TR/xpath20/#id-arithmetic">XML Path Language |
|
88 * (XPath) 2.0, 3.4 Arithmetic Expressions</a> |
|
89 * @see <a href="http://www.w3.org/TR/xpath-functions/#func-numeric-unary-plus">XQuery 1.0 and XPath |
|
90 * 2.0 Functions and Operators, 6.2.7 op:numeric-unary-plus</a> |
|
91 * @see <a href="http://www.w3.org/TR/xpath-functions/#func-numeric-unary-minus">XQuery 1.0 and XPath |
|
92 * 2.0 Functions and Operators, 6.2.8 op:numeric-unary-minus</a> |
|
93 * @author Frans Englich <frans.englich@nokia.com> |
|
94 * @ingroup Patternist_expressions |
|
95 */ |
|
96 class UnaryExpression : public ArithmeticExpression |
|
97 { |
|
98 public: |
|
99 UnaryExpression(const AtomicMathematician::Operator op, |
|
100 const Expression::Ptr &operand, |
|
101 const StaticContext::Ptr &context); |
|
102 |
|
103 virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const; |
|
104 |
|
105 private: |
|
106 Q_DISABLE_COPY(UnaryExpression) |
|
107 }; |
|
108 } |
|
109 |
|
110 QT_END_NAMESPACE |
|
111 |
|
112 QT_END_HEADER |
|
113 |
|
114 #endif |