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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_EmptySequence_H
51 #define Patternist_EmptySequence_H
52 
53 #include <private/qemptycontainer_p.h>
54 
55 QT_BEGIN_NAMESPACE
56 
57 namespace QPatternist
58 {
59     /**
60      * @short Implements the value instance of empty sequence: <tt>()</tt>.
61      *
62      * @author Frans Englich <frans.englich@nokia.com>
63      * @ingroup Patternist_xdm
64      */
65     class EmptySequence : public EmptyContainer
66     {
67     public:
68         /**
69          * @short Creates an EmptySequence that is a replacement for @p
70          * replacementFor.
71          *
72          * @see EmptySequence()
73          */
74         static Expression::Ptr create(const Expression *const replacementFor,
75                                       const StaticContext::Ptr &context);
76 
77 
78         /**
79          * @short Creates an instance of EmptySequence.
80          *
81          * @note In most cases create() should be used, since it takes care of
82          * adjusting source location annotations.
83          *
84          * @see create()
85          */
EmptySequence()86         inline EmptySequence()
87         {
88         }
89 
90         virtual QString stringValue() const;
91 
92         /**
93          * @returns always an empty iterator, an instance of EmptyIterator.
94          */
95         virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &) const;
96 
97         /**
98          * @returns always @c null.
99          */
100         virtual Item evaluateSingleton(const DynamicContext::Ptr &) const;
101 
102         /**
103          * Does nothing.
104          */
105         virtual void evaluateToSequenceReceiver(const DynamicContext::Ptr &) const;
106 
107         /**
108          * @returns always @c false.
109          */
110         virtual bool evaluateEBV(const DynamicContext::Ptr &context) const;
111 
112         /**
113          * @returns always CommonSequenceTypes::Empty
114          */
115         virtual ItemType::Ptr type() const;
116 
117         /**
118          * @returns always CommonSequenceTypes::Empty
119          */
120         virtual SequenceType::Ptr staticType() const;
121 
122         virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;
123         virtual ID id() const;
124         virtual Properties properties() const;
125     };
126 }
127 
128 QT_END_NAMESPACE
129 
130 #endif
131