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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_AtomicComparator_H
53 #define Patternist_AtomicComparator_H
57 #include <private/qitem_p.h>
58 #include <private/qatomictypedispatch_p.h>
70 * @short Base class for classes responsible of comparing two atomic values.
72 * This class is also known as the AtomicParrot.
74 * @ingroup Patternist_xdm
75 * @author Frans Englich <frans.englich@nokia.com>
77 class Q_AUTOTEST_EXPORT AtomicComparator : public AtomicTypeVisitorResult
81 virtual ~AtomicComparator();
83 typedef QExplicitlySharedDataPointer<AtomicComparator> Ptr;
86 * Identifies operators used in value comparisons.
88 * The enum values are bit-significant.
90 * @see <a href="http://www.w3.org/TR/xpath20/#id-value-comparisons">W3C XML Path
91 * Language (XPath) 2.0, 3.5.1 Value Comparisons</a>
96 * Operator <tt>eq</tt> and <tt>=</tt>.
101 * Operator <tt>ne</tt> and <tt>!=</tt>.
103 OperatorNotEqual = 1 << 1,
106 * Operator <tt>gt</tt> and <tt>\></tt>.
108 OperatorGreaterThan = 1 << 2,
111 * Operator <tt>lt</tt> and <tt>\<</tt>.
113 OperatorLessThan = 1 << 3,
116 * One of the operators we use for sorting. The only difference from
117 * OperatorLessThan is that it sees NaN as ordered and smaller than
120 OperatorLessThanNaNLeast = 1 << 4,
123 * One of the operators we use for sorting. The only difference from
124 * OperatorLessThanLeast is that it sees NaN as ordered and larger than
127 OperatorLessThanNaNGreatest = 1 << 5,
130 * Operator <tt>ge</tt> and <tt>\>=</tt>.
132 OperatorGreaterOrEqual = OperatorEqual | OperatorGreaterThan,
135 * Operator <tt>le</tt> and <tt>\<=</tt>.
137 OperatorLessOrEqual = OperatorEqual | OperatorLessThan
140 typedef QFlags<Operator> Operators;
143 * Signifies the result of a value comparison. This is used for value comparisons,
144 * and in the future likely also for sorting.
146 * @see <a href="http://www.w3.org/TR/xpath20/#id-value-comparisons">W3C XML Path
147 * Language (XPath) 2.0, 3.5.1 Value Comparisons</a>
149 enum ComparisonResult
158 * Compares @p op1 and @p op2 and determines the relationship between the two. This
159 * is used for sorting and comparisons. The implementation performs an assert crash,
160 * and must therefore be re-implemented if comparing the relevant values should be
163 * @param op1 the first operand
164 * @param op the operator. How a comparison is carried out shouldn't depend on what the
165 * operator is, but in some cases it is of interest.
166 * @param op2 the second operand
168 virtual ComparisonResult compare(const Item &op1,
169 const AtomicComparator::Operator op,
170 const Item &op2) const;
173 * Determines whether @p op1 and @p op2 are equal. It is the same as calling compare()
174 * and checking whether the return value is Equal, but since comparison testing is such
175 * a common operation, this specialized function exists.
177 * @returns true if @p op1 and @p op2 are equal.
179 * @param op1 the first operand
180 * @param op2 the second operand
182 virtual bool equals(const Item &op1,
183 const Item &op2) const = 0;
186 * Identifies the kind of comparison.
191 * Identifies a general comparison; operator @c =, @c >, @c <=, and so on.
193 AsGeneralComparison = 1,
196 * Identifies a value comparison; operator @c eq, @c lt, @c le, and so on.
202 * Utility function for getting the lexical representation for
203 * the comparison operator @p op. Depending on the @p type argument,
204 * the string returned is either a general comparison or a value comparison
207 * @param op the operator which the display name should be determined for.
208 * @param type signifies whether the returned display name should be for
209 * a value comparison or a general comparison. For example, if @p op is
210 * OperatorEqual and @p type is AsValueComparision, "eq" is returned.
212 static QString displayName(const AtomicComparator::Operator op,
213 const ComparisonType type);
216 Q_DECLARE_OPERATORS_FOR_FLAGS(AtomicComparator::Operators)