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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_CombineNodes_H
51 #define Patternist_CombineNodes_H
52 
53 #include <private/qpaircontainer_p.h>
54 
55 QT_BEGIN_NAMESPACE
56 
57 namespace QPatternist
58 {
59     /**
60      * @short Implements XPath 2.0's operators for combining node sequences: @c union,
61      * @c intersect and @c except.
62      *
63      * @see <a href="http://www.w3.org/TR/xquery/#combining_seq">XQuery 1.0: An XML Query
64      * Language, 3.3.3 Combining QXmlNodeModelIndex Sequences</a>
65      * @author Frans Englich <frans.englich@nokia.com>
66      * @ingroup Patternist_expressions
67      */
68     class Q_AUTOTEST_EXPORT CombineNodes : public PairContainer
69     {
70     public:
71         enum Operator
72         {
73             Union       = 1,
74             Intersect   = 2,
75             Except      = 4
76         };
77 
78         CombineNodes(const Expression::Ptr &operand1,
79                      const Operator op,
80                      const Expression::Ptr &operand2);
81 
82         virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
83         virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;
84         virtual bool evaluateEBV(const DynamicContext::Ptr &context) const;
85         virtual SequenceType::Ptr staticType() const;
86         virtual SequenceType::List expectedOperandTypes() const;
87         virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
88                                           const SequenceType::Ptr &reqType);
89 
90         Operator operatorID() const;
91         virtual ID id() const;
92 
93         /**
94          * Determines the string representation for operator @p op.
95          *
96          * @return "union" if @p op is Union, "intersect" if @p op
97          * is Intersect and "except" if @p op is Except.
98          */
99         static QString displayName(const Operator op);
100 
101         virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;
102 
103     private:
104         const Operator m_operator;
105     };
106 }
107 
108 QT_END_NAMESPACE
109 
110 #endif
111