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_NodeComparison_H 51 #define Patternist_NodeComparison_H 52 53 #include <private/qpaircontainer_p.h> 54 55 QT_BEGIN_NAMESPACE 56 57 namespace QPatternist 58 { 59 60 /** 61 * @short Implements the node comparison operators <tt>\>\></tt>, <tt>\<\<</tt>, and @c is. 62 * 63 * @see <a href="http://www.w3.org/TR/xpath20/#id-node-comparisons">XML Path Language 64 * (XPath) 2.0, 3.5.3 QXmlNodeModelIndex Comparisons</a> 65 * @author Frans Englich <frans.englich@nokia.com> 66 * @ingroup Patternist_expressions 67 */ 68 class Q_AUTOTEST_EXPORT NodeComparison : public PairContainer 69 { 70 public: 71 NodeComparison(const Expression::Ptr &operand1, 72 const QXmlNodeModelIndex::DocumentOrder op, 73 const Expression::Ptr &operand2); 74 75 virtual Item evaluateSingleton(const DynamicContext::Ptr &) const; 76 virtual bool evaluateEBV(const DynamicContext::Ptr &) const; 77 78 virtual SequenceType::List expectedOperandTypes() const; 79 80 virtual QXmlNodeModelIndex::DocumentOrder operatorID() const; 81 /** 82 * If any operator is the empty sequence, the NodeComparison rewrites 83 * into that, since the empty sequence is always the result in that case. 84 */ 85 virtual Expression::Ptr compress(const StaticContext::Ptr &context); 86 87 /** 88 * @returns either CommonSequenceTypes::ZeroOrOneBoolean or 89 * CommonSequenceTypes::ExactlyOneBoolean depending on the static 90 * cardinality of its operands. 91 */ 92 virtual SequenceType::Ptr staticType() const; 93 94 /** 95 * Determines the string representation for a node comparison operator. 96 * 97 * @returns 98 * - "<<" if @p op is Precedes 99 * - ">>" if @p op is Follows 100 * - "is" if @p op is Is 101 */ 102 static QString displayName(const QXmlNodeModelIndex::DocumentOrder op); 103 104 virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const; 105 private: 106 enum Result 107 { 108 Empty, 109 True, 110 False 111 }; 112 inline Result evaluate(const DynamicContext::Ptr &context) const; 113 114 const QXmlNodeModelIndex::DocumentOrder m_op; 115 116 }; 117 } 118 119 QT_END_NAMESPACE 120 121 #endif 122