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These rights are described in The Qt Company LGPL Exception 28 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. 29 ** 30 ** GNU General Public License Usage 31 ** Alternatively, this file may be used under the terms of the GNU 32 ** General Public License version 3.0 as published by the Free Software 33 ** Foundation and appearing in the file LICENSE.GPL included in the 34 ** packaging of this file. Please review the following information to 35 ** ensure the GNU General Public License version 3.0 requirements will be 36 ** met: http://www.gnu.org/copyleft/gpl.html. 37 ** 38 ** $QT_END_LICENSE$ 39 ** 40 ****************************************************************************/ 41 42 // 43 // W A R N I N G 44 // ------------- 45 // 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. 49 // 50 // We mean it. 51 52 #ifndef Patternist_AtomicComparator_H 53 #define Patternist_AtomicComparator_H 54 55 #include <QFlags> 56 57 #include "qitem_p.h" 58 #include "qatomictypedispatch_p.h" 59 60 QT_BEGIN_HEADER 61 62 QT_BEGIN_NAMESPACE 63 64 class QString; 65 66 namespace QPatternist 67 { 68 69 /** 70 * @short Base class for classes responsible of comparing two atomic values. 71 * 72 * This class is also known as the AtomicParrot. 73 * 74 * @ingroup Patternist_xdm 75 * @author Frans Englich <frans.englich@nokia.com> 76 */ 77 class Q_AUTOTEST_EXPORT AtomicComparator : public AtomicTypeVisitorResult 78 { 79 public: 80 AtomicComparator(); 81 virtual ~AtomicComparator(); 82 83 typedef QExplicitlySharedDataPointer<AtomicComparator> Ptr; 84 85 /** 86 * Identifies operators used in value comparisons. 87 * 88 * The enum values are bit-significant. 89 * 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> 92 */ 93 enum Operator 94 { 95 /** 96 * Operator <tt>eq</tt> and <tt>=</tt>. 97 */ 98 OperatorEqual = 1, 99 100 /** 101 * Operator <tt>ne</tt> and <tt>!=</tt>. 102 */ 103 OperatorNotEqual = 1 << 1, 104 105 /** 106 * Operator <tt>gt</tt> and <tt>\></tt>. 107 */ 108 OperatorGreaterThan = 1 << 2, 109 110 /** 111 * Operator <tt>lt</tt> and <tt>\<</tt>. 112 */ 113 OperatorLessThan = 1 << 3, 114 115 /** 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 118 * other numbers. 119 */ 120 OperatorLessThanNaNLeast = 1 << 4, 121 122 /** 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 125 * other numbers. 126 */ 127 OperatorLessThanNaNGreatest = 1 << 5, 128 129 /** 130 * Operator <tt>ge</tt> and <tt>\>=</tt>. 131 */ 132 OperatorGreaterOrEqual = OperatorEqual | OperatorGreaterThan, 133 134 /** 135 * Operator <tt>le</tt> and <tt>\<=</tt>. 136 */ 137 OperatorLessOrEqual = OperatorEqual | OperatorLessThan 138 }; 139 140 typedef QFlags<Operator> Operators; 141 142 /** 143 * Signifies the result of a value comparison. This is used for value comparisons, 144 * and in the future likely also for sorting. 145 * 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> 148 */ 149 enum ComparisonResult 150 { 151 LessThan = 1, 152 Equal = 2, 153 GreaterThan = 4, 154 Incomparable = 8 155 }; 156 157 /** 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 161 * possible. 162 * 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 167 */ 168 virtual ComparisonResult compare(const Item &op1, 169 const AtomicComparator::Operator op, 170 const Item &op2) const; 171 172 /** 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. 176 * 177 * @returns true if @p op1 and @p op2 are equal. 178 * 179 * @param op1 the first operand 180 * @param op2 the second operand 181 */ 182 virtual bool equals(const Item &op1, 183 const Item &op2) const = 0; 184 185 /** 186 * Identifies the kind of comparison. 187 */ 188 enum ComparisonType 189 { 190 /** 191 * Identifies a general comparison; operator @c =, @c >, @c <=, and so on. 192 */ 193 AsGeneralComparison = 1, 194 195 /** 196 * Identifies a value comparison; operator @c eq, @c lt, @c le, and so on. 197 */ 198 AsValueComparison 199 }; 200 201 /** 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 205 * operator. 206 * 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. 211 */ 212 static QString displayName(const AtomicComparator::Operator op, 213 const ComparisonType type); 214 215 }; 216 Q_DECLARE_OPERATORS_FOR_FLAGS(AtomicComparator::Operators) 217 } 218 219 QT_END_NAMESPACE 220 221 QT_END_HEADER 222 223 #endif 224