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39 
40 //
41 //  W A R N I N G
42 //  -------------
43 //
44 // This file is not part of the Qt API.  It exists purely as an
45 // implementation detail.  This header file may change from version to
46 // version without notice, or even be removed.
47 //
48 // We mean it.
49 
50 #ifndef Patternist_Literal_H
51 #define Patternist_Literal_H
52 
53 #include <private/qemptycontainer_p.h>
54 
55 QT_BEGIN_NAMESPACE
56 
57 namespace QPatternist
58 {
59     /**
60      * @short Houses an AtomicValue, making it available as an Expression.
61      *
62      * This is not only literals that can be created via the XQuery syntax(strings and numbers), but
63      * all other atomic values, such as <tt>xs:date</tt> or <tt>xs:time</tt>.
64      *
65      * @see <a href="http://www.w3.org/TR/xquery/#id-literals">XQuery 1.0: An XML Query Language,
66      * 3.1.1 Literals</a>
67      * @author Frans Englich <frans.englich@nokia.com>
68      * @ingroup Patternist_expressions
69      */
70     class Literal : public EmptyContainer
71     {
72     public:
73         /**
74          * Creates a Literal that represents @p item.
75          *
76          * @param item must be non-null and cannot be a QXmlNodeModelIndex.
77          */
78         Literal(const Item &item);
79 
80         virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;
81         virtual bool evaluateEBV(const DynamicContext::Ptr &context) const;
82         void evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const;
83 
84         virtual SequenceType::Ptr staticType() const;
85         virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;
86         virtual ID id() const;
87         virtual QString description() const;
88 
89         /**
90          * @returns Expression::DisableElimination and Expression::IsEvaluated
91          */
92         virtual Properties properties() const;
93 
94         /**
95          * Declaring the return value of this function a const reference, leads
96          * to crashes in patternistview, for a to me unknown reason.
97          */
item()98         inline Item item() const
99         {
100             return m_item;
101         }
102 
103     private:
104         const Item m_item;
105     };
106 
107     /**
108      * @short Creates a Literal that wraps @p item, and returns it.
109      *
110      * This simplifies code. Instead of writing:
111      *
112      * @code
113      * Expression::Ptr(new Literal(item));
114      * @endcode
115      *
116      * One can write:
117      *
118      * @code
119      * wrapLiteral(item);
120      * @endcode
121      *
122      * This function is not declared static, because it breaks the build on
123      * at least aix-xlc-64.
124      *
125      * @relates Literal
126      */
wrapLiteral(const Item & item,const StaticContext::Ptr & context,const SourceLocationReflection * const r)127     inline Expression::Ptr wrapLiteral(const Item &item,
128                                        const StaticContext::Ptr &context,
129                                        const SourceLocationReflection *const r)
130     {
131         Q_ASSERT(item);
132 
133         const Expression::Ptr retval(new Literal(item));
134         context->addLocation(retval.data(), context->locationFor(r));
135 
136         return retval;
137     }
138 }
139 
140 QT_END_NAMESPACE
141 
142 #endif
143