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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_ValueComparison_H
51 #define Patternist_ValueComparison_H
52 
53 #include <private/qatomiccomparator_p.h>
54 #include <private/qpaircontainer_p.h>
55 #include <private/qcomparisonplatform_p.h>
56 
57 QT_BEGIN_NAMESPACE
58 
59 namespace QPatternist
60 {
61 
62     /**
63      * @short Implements XPath 2.0 value comparions, such as the <tt>eq</tt> operator.
64      *
65      * ComparisonPlatform is inherited with @c protected scope because ComparisonPlatform
66      * must access members of ValueComparison.
67      *
68      * @see <a href="http://www.w3.org/TR/xpath20/#id-value-comparisons">XML Path Language
69      * (XPath) 2.0, 3.5.1 Value Comparisons</a>
70      * @author Frans Englich <frans.englich@nokia.com>
71      * @ingroup Patternist_expressions
72      */
73     class Q_AUTOTEST_EXPORT ValueComparison
74       : public PairContainer, public ComparisonPlatform<ValueComparison, true>
75     {
76     public:
77         ValueComparison(const Expression::Ptr &op1,
78                         const AtomicComparator::Operator op,
79                         const Expression::Ptr &op2);
80         ~ValueComparison();
81 
82         virtual Item evaluateSingleton(const DynamicContext::Ptr &) const;
83 
84         virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
85                                           const SequenceType::Ptr &reqType);
86 
87         /**
88          * @returns always CommonSequenceTypes::ExactlyOneBoolean
89          */
90         virtual SequenceType::Ptr staticType() const;
91 
92         virtual SequenceType::List expectedOperandTypes() const;
93 
94         /**
95          * @returns IDValueComparison
96          */
97         virtual ID id() const;
98 
99         virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;
100         virtual QList<QExplicitlySharedDataPointer<OptimizationPass> > optimizationPasses() const;
101 
102         /**
103          * Overridden to optimize case-insensitive compares.
104          */
105         virtual Expression::Ptr compress(const StaticContext::Ptr &context);
106 
107         /**
108          * @returns the operator that this ValueComparison is using.
109          */
operatorID()110         inline AtomicComparator::Operator operatorID() const
111         {
112             return m_operator;
113         }
114 
115         /**
116          * It is considered that the string value from @p op1 will be compared against @p op2. This
117          * function determines whether the user intends the comparison to be case insensitive. If
118          * that is the case @c true is returned, and the operands are re-written appropriately.
119          *
120          * This is a helper function for Expression classes that compares strings.
121          *
122          * @see ComparisonPlatform::useCaseInsensitiveComparator()
123          */
124         static bool isCaseInsensitiveCompare(Expression::Ptr &op1, Expression::Ptr &op2);
125 
126     private:
127         const AtomicComparator::Operator m_operator;
128     };
129 }
130 
131 QT_END_NAMESPACE
132 
133 #endif
134