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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.
52 #ifndef Patternist_NodeComparison_H
53 #define Patternist_NodeComparison_H
55 #include <private/qpaircontainer_p.h>
65 * @short Implements the node comparison operators <tt>\>\></tt>, <tt>\<\<</tt>, and @c is.
67 * @see <a href="http://www.w3.org/TR/xpath20/#id-node-comparisons">XML Path Language
68 * (XPath) 2.0, 3.5.3 QXmlNodeModelIndex Comparisons</a>
69 * @author Frans Englich <frans.englich@nokia.com>
70 * @ingroup Patternist_expressions
72 class Q_AUTOTEST_EXPORT NodeComparison : public PairContainer
75 NodeComparison(const Expression::Ptr &operand1,
76 const QXmlNodeModelIndex::DocumentOrder op,
77 const Expression::Ptr &operand2);
79 virtual Item evaluateSingleton(const DynamicContext::Ptr &) const;
80 virtual bool evaluateEBV(const DynamicContext::Ptr &) const;
82 virtual SequenceType::List expectedOperandTypes() const;
84 virtual QXmlNodeModelIndex::DocumentOrder operatorID() const;
86 * If any operator is the empty sequence, the NodeComparison rewrites
87 * into that, since the empty sequence is always the result in that case.
89 virtual Expression::Ptr compress(const StaticContext::Ptr &context);
92 * @returns either CommonSequenceTypes::ZeroOrOneBoolean or
93 * CommonSequenceTypes::ExactlyOneBoolean depending on the static
94 * cardinality of its operands.
96 virtual SequenceType::Ptr staticType() const;
99 * Determines the string representation for a node comparison operator.
102 * - "<<" if @p op is Precedes
103 * - ">>" if @p op is Follows
104 * - "is" if @p op is Is
106 static QString displayName(const QXmlNodeModelIndex::DocumentOrder op);
108 virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;
116 inline Result evaluate(const DynamicContext::Ptr &context) const;
118 const QXmlNodeModelIndex::DocumentOrder m_op;