/****************************************************************************

**

** All rights reserved.

** Contact: Nokia Corporation (qt-info@nokia.com)

**

** This file is part of the QtXmlPatterns module of the Qt Toolkit.

**

** $QT_BEGIN_LICENSE:LGPL$

** No Commercial Usage

** This file contains pre-release code and may not be distributed.

** You may use this file in accordance with the terms and conditions

** contained in the Technology Preview License Agreement accompanying

** this package.

**

** GNU Lesser General Public License Usage

** Alternatively, this file may be used under the terms of the GNU Lesser

** General Public License version 2.1 as published by the Free Software

** Foundation and appearing in the file LICENSE.LGPL included in the

** packaging of this file.  Please review the following information to

** ensure the GNU Lesser General Public License version 2.1 requirements

** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.

**

** In addition, as a special exception, Nokia gives you certain additional

** rights.  These rights are described in the Nokia Qt LGPL Exception

** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.

**

** If you have questions regarding the use of this file, please contact

** Nokia at qt-info@nokia.com.

**

**

**

**

**

**

**

**

** $QT_END_LICENSE$

**

****************************************************************************/

#include "qcommonsequencetypes_p.h"

#include "qexceptiterator_p.h"

#include "qgenericsequencetype_p.h"

#include "qintersectiterator_p.h"

#include "qitemmappingiterator_p.h"

#include "qnodesort_p.h"

#include "qunioniterator_p.h"

#include "qcombinenodes_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

CombineNodes::CombineNodes(const Expression::Ptr &operand1,

                           const Operator op,

                           const Expression::Ptr &operand2) : PairContainer(operand1, operand2),

                                                              m_operator(op)

{

    Q_ASSERT(op == Union    ||

             op == Except   ||

             op == Intersect);

}

Item::Iterator::Ptr CombineNodes::evaluateSequence(const DynamicContext::Ptr &context) const

{

    const Item::Iterator::Ptr op1(m_operand1->evaluateSequence(context));

    const Item::Iterator::Ptr op2(m_operand2->evaluateSequence(context));

    switch(m_operator)

    {

        case Intersect:

            return Item::Iterator::Ptr(new IntersectIterator(op1, op2));

        case Except:

            return Item::Iterator::Ptr(new ExceptIterator(op1, op2));

        default:

        {

            Q_ASSERT(m_operator == Union);

            return Item::Iterator::Ptr(new UnionIterator(op1, op2));

        }

    }

}

Item CombineNodes::evaluateSingleton(const DynamicContext::Ptr &context) const

{

    return evaluateSequence(context)->next();

}

Expression::Ptr CombineNodes::typeCheck(const StaticContext::Ptr &context,

                                        const SequenceType::Ptr &reqType)

{

    const Expression::Ptr me(PairContainer::typeCheck(context, reqType));

    m_operand1 = NodeSortExpression::wrapAround(m_operand1, context);

    m_operand2 = NodeSortExpression::wrapAround(m_operand2, context);

    return me;

}

bool CombineNodes::evaluateEBV(const DynamicContext::Ptr &context) const

{

    /* If it's the union operator, we can possibly avoid

     * evaluating the second operand. */

    if(m_operator == Union)

    {

        return m_operand1->evaluateEBV(context) ||

               m_operand2->evaluateEBV(context);

    }

    else

        return PairContainer::evaluateEBV(context);

}

QString CombineNodes::displayName(const Operator op)

{

    switch(op)

    {

        case Intersect:

            return QLatin1String("intersect");

        case Except:

            return QLatin1String("except");

        default:

        {

            Q_ASSERT(op == Union);

            return QLatin1String("union");

        }

    }

}

SequenceType::Ptr CombineNodes::staticType() const

{

    const SequenceType::Ptr t1(m_operand1->staticType());

    const SequenceType::Ptr t2(m_operand2->staticType());

     Cardinality card;

     /* Optimization: the cardinality can be better inferred for

      * Intersect and Except, although it's not trivial code. */

     if(m_operator == Union)

         card = t1->cardinality() | t2->cardinality();

     else /* Except. */

         card = Cardinality::zeroOrMore();

     return makeGenericSequenceType(t1->itemType() | t2->itemType(), card);

}

SequenceType::List CombineNodes::expectedOperandTypes() const

{

    SequenceType::List result;

    result.append(CommonSequenceTypes::ZeroOrMoreNodes);

    result.append(CommonSequenceTypes::ZeroOrMoreNodes);

    return result;

}

CombineNodes::Operator CombineNodes::operatorID() const

{

    return m_operator;

}

ExpressionVisitorResult::Ptr CombineNodes::accept(const ExpressionVisitor::Ptr &visitor) const

{

    return visitor->visit(this);

}

Expression::ID CombineNodes::id() const

{

    return IDCombineNodes;

}

QT_END_NAMESPACE