/****************************************************************************+
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**+
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** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).+
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** All rights reserved.+
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** Contact: Nokia Corporation (qt-info@nokia.com)+
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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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** No Commercial Usage+
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** This file contains pre-release code and may not be distributed.+
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** You may use this file in accordance with the terms and conditions+
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** contained in the Technology Preview License Agreement accompanying+
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** this package.+
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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 2.1 as published by the Free Software+
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** Foundation and appearing in the file LICENSE.LGPL 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 2.1 requirements+
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.+
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**+
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** In addition, as a special exception, Nokia gives you certain additional+
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** rights.  These rights are described in the Nokia Qt LGPL Exception+
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.+
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**+
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** If you have questions regarding the use of this file, please contact+
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** Nokia at qt-info@nokia.com.+
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**+
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**+
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**+
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**+
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**+
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**+
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**+
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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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#include "qcommonsequencetypes_p.h"+
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#include "qexceptiterator_p.h"+
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#include "qgenericsequencetype_p.h"+
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#include "qintersectiterator_p.h"+
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#include "qitemmappingiterator_p.h"+
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#include "qnodesort_p.h"+
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#include "qunioniterator_p.h"+
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+
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#include "qcombinenodes_p.h"+
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+
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QT_BEGIN_NAMESPACE+
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+
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using namespace QPatternist;+
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+
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CombineNodes::CombineNodes(const Expression::Ptr &operand1,+
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                           const Operator op,+
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                           const Expression::Ptr &operand2) : PairContainer(operand1, operand2),+
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                                                              m_operator(op)+
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{+
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    Q_ASSERT(op == Union    ||+
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             op == Except   ||+
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             op == Intersect);+
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}+
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+
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Item::Iterator::Ptr CombineNodes::evaluateSequence(const DynamicContext::Ptr &context) const+
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{+
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    const Item::Iterator::Ptr op1(m_operand1->evaluateSequence(context));+
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    const Item::Iterator::Ptr op2(m_operand2->evaluateSequence(context));+
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+
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    switch(m_operator)+
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    {+
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        case Intersect:+
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            return Item::Iterator::Ptr(new IntersectIterator(op1, op2));+
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        case Except:+
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            return Item::Iterator::Ptr(new ExceptIterator(op1, op2));+
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        default:+
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        {+
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            Q_ASSERT(m_operator == Union);+
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            return Item::Iterator::Ptr(new UnionIterator(op1, op2));+
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        }+
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    }+
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}+
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+
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Item CombineNodes::evaluateSingleton(const DynamicContext::Ptr &context) const+
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{+
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    return evaluateSequence(context)->next();+
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}+
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+
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Expression::Ptr CombineNodes::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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    const Expression::Ptr me(PairContainer::typeCheck(context, reqType));+
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+
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    m_operand1 = NodeSortExpression::wrapAround(m_operand1, context);+
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    m_operand2 = NodeSortExpression::wrapAround(m_operand2, context);+
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+
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    return me;+
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}+
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+
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bool CombineNodes::evaluateEBV(const DynamicContext::Ptr &context) const+
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{+
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    /* If it's the union operator, we can possibly avoid+
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     * evaluating the second operand. */+
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+
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    if(m_operator == Union)+
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    {+
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        return m_operand1->evaluateEBV(context) ||+
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               m_operand2->evaluateEBV(context);+
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    }+
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    else+
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        return PairContainer::evaluateEBV(context);+
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}+
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+
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QString CombineNodes::displayName(const Operator op)+
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{+
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    switch(op)+
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    {+
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        case Intersect:+
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            return QLatin1String("intersect");+
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        case Except:+
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            return QLatin1String("except");+
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        default:+
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        {+
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            Q_ASSERT(op == Union);+
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            return QLatin1String("union");+
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        }+
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    }+
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}+
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+
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SequenceType::Ptr CombineNodes::staticType() const+
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{+
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    const SequenceType::Ptr t1(m_operand1->staticType());+
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    const SequenceType::Ptr t2(m_operand2->staticType());+
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+
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     Cardinality card;+
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+
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     /* Optimization: the cardinality can be better inferred for+
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      * Intersect and Except, although it's not trivial code. */+
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     if(m_operator == Union)+
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         card = t1->cardinality() | t2->cardinality();+
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     else /* Except. */+
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         card = Cardinality::zeroOrMore();+
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+
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     return makeGenericSequenceType(t1->itemType() | t2->itemType(), card);+
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}+
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+
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SequenceType::List CombineNodes::expectedOperandTypes() const+
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{+
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    SequenceType::List result;+
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    result.append(CommonSequenceTypes::ZeroOrMoreNodes);+
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    result.append(CommonSequenceTypes::ZeroOrMoreNodes);+
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    return result;+
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}+
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+
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CombineNodes::Operator CombineNodes::operatorID() const+
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{+
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    return m_operator;+
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}+
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+
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ExpressionVisitorResult::Ptr CombineNodes::accept(const ExpressionVisitor::Ptr &visitor) const+
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{+
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    return visitor->visit(this);+
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}+
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+
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Expression::ID CombineNodes::id() const+
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{+
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    return IDCombineNodes;+
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}+
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+
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QT_END_NAMESPACE+
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