1 /**************************************************************************** 2 ** 3 ** Copyright (C) 2016 The Qt Company Ltd. 4 ** Contact: https://www.qt.io/licensing/ 5 ** 6 ** This file is part of the QtXmlPatterns module of the Qt Toolkit. 7 ** 8 ** $QT_BEGIN_LICENSE:LGPL$ 9 ** Commercial License Usage 10 ** Licensees holding valid commercial Qt licenses may use this file in 11 ** accordance with the commercial license agreement provided with the 12 ** Software or, alternatively, in accordance with the terms contained in 13 ** a written agreement between you and The Qt Company. For licensing terms 14 ** and conditions see https://www.qt.io/terms-conditions. For further 15 ** information use the contact form at https://www.qt.io/contact-us. 16 ** 17 ** GNU Lesser General Public License Usage 18 ** Alternatively, this file may be used under the terms of the GNU Lesser 19 ** General Public License version 3 as published by the Free Software 20 ** Foundation and appearing in the file LICENSE.LGPL3 included in the 21 ** packaging of this file. Please review the following information to 22 ** ensure the GNU Lesser General Public License version 3 requirements 23 ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. 24 ** 25 ** GNU General Public License Usage 26 ** Alternatively, this file may be used under the terms of the GNU 27 ** General Public License version 2.0 or (at your option) the GNU General 28 ** Public license version 3 or any later version approved by the KDE Free 29 ** Qt Foundation. The licenses are as published by the Free Software 30 ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 31 ** included in the packaging of this file. Please review the following 32 ** information to ensure the GNU General Public License requirements will 33 ** be met: https://www.gnu.org/licenses/gpl-2.0.html and 34 ** https://www.gnu.org/licenses/gpl-3.0.html. 35 ** 36 ** $QT_END_LICENSE$ 37 ** 38 ****************************************************************************/ 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_DistinctIterator_H 51 #define Patternist_DistinctIterator_H 52 53 #include <QList> 54 55 #include <private/qexpression_p.h> 56 #include <private/qitem_p.h> 57 #include <private/qatomiccomparator_p.h> 58 #include <private/qcomparisonplatform_p.h> 59 #include <private/qsourcelocationreflection_p.h> 60 61 QT_BEGIN_NAMESPACE 62 63 namespace QPatternist 64 { 65 66 /** 67 * @short Filters another sequence by removing duplicates such that the items are unique. 68 * 69 * DistinctIterator takes an input sequence, and returns a sequence where each 70 * item is unique. Thus, DistinctIterator removes the duplicates of items 71 * in a sequence. DistinctIterator is central in the implementation of the 72 * <tt>fn:distinct-values()</tt> function. 73 * 74 * @see <a href="http://www.w3.org/TR/xpath-functions/#func-distinct-values">XQuery 1.0 75 * and XPath 2.0 Functions and Operators, 15.1.6 fn:distinct-values</a> 76 * @author Frans Englich <frans.englich@nokia.com> 77 * @ingroup Patternist_iterators 78 */ 79 class DistinctIterator : public Item::Iterator 80 , public ComparisonPlatform<DistinctIterator, false> 81 , public SourceLocationReflection 82 { 83 public: 84 /** 85 * Creates a DistinctIterator. 86 * @param comp the AtomicComparator to be used for comparing values. This may be @c null, 87 * meaning the IndexOfIterator iterator will dynamically determine what comparator to use 88 * @param seq the sequence whose duplicates should be filtered out 89 * @param context the usual context, used for error reporting and by AtomicComparators. 90 * @param expression the Expression that this DistinctIterator is 91 * evaluating for. It is used for error reporting, via 92 * actualReflection(). 93 */ 94 DistinctIterator(const Item::Iterator::Ptr &seq, 95 const AtomicComparator::Ptr &comp, 96 const Expression::ConstPtr &expression, 97 const DynamicContext::Ptr &context); 98 99 virtual Item next(); 100 virtual Item current() const; 101 virtual xsInteger position() const; 102 virtual Item::Iterator::Ptr copy() const; 103 virtual const SourceLocationReflection *actualReflection() const; 104 operatorID()105 inline AtomicComparator::Operator operatorID() const 106 { 107 return AtomicComparator::OperatorEqual; 108 } 109 110 private: 111 const Item::Iterator::Ptr m_seq; 112 const DynamicContext::Ptr m_context; 113 const Expression::ConstPtr m_expr; 114 Item m_current; 115 xsInteger m_position; 116 Item::List m_processed; 117 }; 118 } 119 120 QT_END_NAMESPACE 121 122 #endif 123