339 lines
13 KiB
C++
339 lines
13 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2016 The Qt Company Ltd.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the QtXmlPatterns module of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 3 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL3 included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 3 requirements
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** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 2.0 or (at your option) the GNU General
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** Public license version 3 or any later version approved by the KDE Free
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** Qt Foundation. The licenses are as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
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** included in the packaging of this file. Please review the following
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** information to ensure the GNU General Public License requirements will
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** be met: https://www.gnu.org/licenses/gpl-2.0.html and
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** https://www.gnu.org/licenses/gpl-3.0.html.
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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//
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// W A R N I N G
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// -------------
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//
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// This file is not part of the Qt API. It exists purely as an
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// implementation detail. This header file may change from version to
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// version without notice, or even be removed.
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//
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// We mean it.
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#ifndef Patternist_SequenceFNs_H
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#define Patternist_SequenceFNs_H
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#include <private/qatomiccomparator_p.h>
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#include <private/qcomparisonplatform_p.h>
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#include <private/qliteral_p.h>
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#include <private/qfunctioncall_p.h>
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/**
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* @file
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* @short Contains classes implementing the functions found in
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* <a href="http://www.w3.org/TR/xpath-functions/#general-seq-funcs">XQuery 1.0 and
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* XPath 2.0 Functions and Operators, 15.1 General Functions and Operators on Sequences</a>.
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*
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* @todo document that some functions have both eval funcs implented.
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*
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* @ingroup Patternist_functions
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*/
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QT_BEGIN_NAMESPACE
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namespace QPatternist
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{
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/**
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* @short Implements the function <tt>fn:boolean()</tt>.
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*
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* @see EBVExtractor
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* @ingroup Patternist_functions
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* @author Frans Englich <frans.englich@nokia.com>
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*/
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class BooleanFN : public FunctionCall
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{
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public:
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virtual bool evaluateEBV(const DynamicContext::Ptr &context) const;
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/**
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* If @p reqType is CommonSequenceTypes::EBV, the type check of
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* the operand is returned. Hence, this removes redundant calls
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* to <tt>fn:boolean()</tt>.
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*/
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virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
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const SequenceType::Ptr &reqType);
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};
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/**
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* @short Implements the function <tt>fn:index-of()</tt>.
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*
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* @ingroup Patternist_functions
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* @author Frans Englich <frans.englich@nokia.com>
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*/
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class IndexOfFN : public FunctionCall,
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public ComparisonPlatform<IndexOfFN, false>
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{
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public:
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inline IndexOfFN() : ComparisonPlatform<IndexOfFN, false>()
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{
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}
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virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
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virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
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const SequenceType::Ptr &reqType);
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inline AtomicComparator::Operator operatorID() const
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{
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return AtomicComparator::OperatorEqual;
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}
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};
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/**
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* @short Implements the functions <tt>fn:exists()</tt> and <tt>fn:empty()</tt>.
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*
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* Existence is a template value class. Appropriate implementations are achieved
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* by instantiating it with either IDExistsFN or IDEmptyFN.
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*
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* @ingroup Patternist_functions
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* @author Frans Englich <frans.englich@nokia.com>
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*/
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template<const Expression::ID Id>
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class Existence : public FunctionCall
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{
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public:
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virtual bool evaluateEBV(const DynamicContext::Ptr &context) const
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{
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if(Id == IDExistsFN)
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return !m_operands.first()->evaluateSequence(context)->isEmpty();
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else
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return m_operands.first()->evaluateSequence(context)->isEmpty();
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}
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/**
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* Attempts to rewrite to @c false or @c true by looking at the static
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* cardinality of its operand.
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*/
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virtual Expression::Ptr compress(const StaticContext::Ptr &context)
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{
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// RVCT doesn't like using template parameter in trinary operator when the trinary operator result is
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// passed directly into another constructor.
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Q_ASSERT(Id == IDExistsFN || Id == IDEmptyFN);
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const Expression::Ptr me(FunctionCall::compress(context));
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if(me != this)
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return me;
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// RVCT doesn't like using template parameter in trinary operator when the trinary operator result is
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// passed directly into another constructor.
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Expression::ID tempId = Id;
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const Cardinality myCard((tempId == IDExistsFN) ? Cardinality::oneOrMore() : Cardinality::empty());
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const Cardinality card(m_operands.first()->staticType()->cardinality());
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if(myCard.isMatch(card))
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{ /* Since the dynamic type always is narrower than the static type or equal, and that the
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static type is in scope, it means we will always be true. */
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return wrapLiteral(CommonValues::BooleanTrue, context, this);
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}
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else
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{
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/* Is it even possible to hit? */
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if(myCard.canMatch(card))
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{
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return me;
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}
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else
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{ /* We can never hit. */
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return wrapLiteral(CommonValues::BooleanFalse, context, this);
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}
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}
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}
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};
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/**
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* @short Implements the function <tt>fn:distinct-values()</tt>.
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*
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* @ingroup Patternist_functions
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* @author Frans Englich <frans.englich@nokia.com>
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*/
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class DistinctValuesFN : public FunctionCall,
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public ComparisonPlatform<IndexOfFN, false>
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{
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public:
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inline DistinctValuesFN() : ComparisonPlatform<IndexOfFN, false>()
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{
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}
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virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
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/**
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* Performs necessary type checks, but also implements the optimization
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* of rewriting to its operand if the operand's cardinality is zero-or-one
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* or exactly-one.
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*/
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virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
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const SequenceType::Ptr &reqType);
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/**
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* @returns a type whose item type is the type of the first operand, and
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* a cardinality which is non-empty if the first operand's type is non-empty
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* and allows exactly-one. The latter is needed for operands which has the
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* cardinality 2+, since distinct-values possibly removes items from the
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* source sequence.
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*/
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virtual SequenceType::Ptr staticType() const;
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protected:
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inline AtomicComparator::Operator operatorID() const
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{
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return AtomicComparator::OperatorEqual;
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}
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};
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/**
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* @short Implements the function <tt>fn:insert-before()</tt>.
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*
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* @todo docs, explain why evaluateSequence and evaluateSingleton is implemented
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*
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* @ingroup Patternist_functions
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* @author Frans Englich <frans.englich@nokia.com>
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*/
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class InsertBeforeFN : public FunctionCall
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{
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public:
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virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
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virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;
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/**
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* Implements the static enferences rules. The function's static item type
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* is the union type of the first and third argument, and the cardinality is
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* the cardinalities of the two operands added together. For example,
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* insert-before((1, "str"), 1, xs:double(0)) has the static type xs:anyAtomicType+.
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*
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* @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_insert_before">XQuery 1.0
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* and XPath 2.0 Formal Semantics, 7.2.15 The fn:insert-before function</a>
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*/
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virtual SequenceType::Ptr staticType() const;
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};
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/**
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* @short Implements the function <tt>fn:remove()</tt>.
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*
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* @ingroup Patternist_functions
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* @author Frans Englich <frans.englich@nokia.com>
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*/
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class RemoveFN : public FunctionCall
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{
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public:
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virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
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virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;
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/**
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* Implements the static enferences rules, "Since one item may be removed
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* from the sequence, the resulting type is made optional:"
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*
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* <tt>statEnv |- (FN-URI,"remove")(Type, Type1) : prime(Type) * quantifier(Type)?</tt>
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*
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* However, because Patternist's type system is more fine grained than Formal Semantics,
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* the sequence isn't made optional. Instead its minimum length is reduced with one.
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*
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* @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_remove">XQuery 1.0
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* and XPath 2.0 Formal Semantics, 7.2.11 The fn:remove function</a>
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*/
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virtual SequenceType::Ptr staticType() const;
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};
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/**
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* @short Implements the function <tt>fn:reverse()</tt>.
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*
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* @ingroup Patternist_functions
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* @author Frans Englich <frans.englich@nokia.com>
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*/
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class ReverseFN : public FunctionCall
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{
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public:
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virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
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virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
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const SequenceType::Ptr &reqType);
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/**
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* Formally speaking, the type inference is:
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*
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@verbatim
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statEnv |- (FN-URI,"reverse")(Type) : prime(Type) * quantifier(Type)
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@endverbatim
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*
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* @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_reverse">XQuery 1.0
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* and XPath 2.0 Formal Semantics, 7.2.12 The fn:reverse function</a>
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* @returns the static type of the function's first argument.
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*/
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virtual SequenceType::Ptr staticType() const;
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};
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/**
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* @short Implements the function <tt>fn:subsequence()</tt>.
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*
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* @ingroup Patternist_functions
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* @author Frans Englich <frans.englich@nokia.com>
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* @todo Type inference can be made stronger for this function
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*/
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class SubsequenceFN : public FunctionCall
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{
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public:
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SubsequenceFN();
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virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
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virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;
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virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,
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const SequenceType::Ptr &reqType);
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/**
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* This function implements rewrites the SubsequenceFN instance into an
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* empty sequence if its third argument, the sequence length argument, is
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* evaluated and is effectively equal or less than zero.
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*/
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virtual Expression::Ptr compress(const StaticContext::Ptr &context);
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/**
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* Partially implements the static type inference rules.
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*
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* @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_subsequence">XQuery 1.0
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* and XPath 2.0 Formal Semantics, 7.2.13 The fn:subsequence function</a>
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*/
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virtual SequenceType::Ptr staticType() const;
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private:
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bool m_hasTypeChecked;
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};
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}
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QT_END_NAMESPACE
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#endif
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