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

**

** 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 "qcommonvalues_p.h"

#include "qemptysequence_p.h"

#include "qinteger_p.h"

#include "qschemanumeric_p.h"

#include "qrangeiterator_p.h"

#include "qnodecomparison_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

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

                               const QXmlNodeModelIndex::DocumentOrder op,

                               const Expression::Ptr &operand2)

                               : PairContainer(operand1, operand2)

                               , m_op(op)

{

    Q_ASSERT(op == QXmlNodeModelIndex::Precedes   ||

             op == QXmlNodeModelIndex::Follows    ||

             op == QXmlNodeModelIndex::Is);

}

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

{

    switch(evaluate(context))

    {

        case True:

            return CommonValues::BooleanTrue;

        case False:

            return CommonValues::BooleanFalse;

        default:

            return Item();

    }

}

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

{

    switch(evaluate(context))

    {

        case True:

            return true;

        default:

            /* We include the empty sequence here. */

            return false;

    }

}

NodeComparison::Result NodeComparison::evaluate(const DynamicContext::Ptr &context) const

{

    const Item op1(m_operand1->evaluateSingleton(context));

    if(!op1)

        return Empty;

    const Item op2(m_operand2->evaluateSingleton(context));

    if(!op2)

        return Empty;

    /* We just returns an arbitrary value, since there's no order defined for nodes from different

     * models, except for that the return value must be stable. */

    if(op1.asNode().model() != op2.asNode().model())

        return False;

    switch(m_op)

    {

        case QXmlNodeModelIndex::Is:

            return op1.asNode().is(op2.asNode()) ? True : False;

        case QXmlNodeModelIndex::Precedes:

            return op1.asNode().compareOrder(op2.asNode()) == QXmlNodeModelIndex::Precedes ? True : False;

        default:

        {

            Q_ASSERT(m_op == QXmlNodeModelIndex::Follows);

            return op1.asNode().compareOrder(op2.asNode()) == QXmlNodeModelIndex::Follows ? True : False;

        }

    }

}

SequenceType::List NodeComparison::expectedOperandTypes() const

{

    SequenceType::List result;

    result.append(CommonSequenceTypes::ZeroOrOneNode);

    result.append(CommonSequenceTypes::ZeroOrOneNode);

    return result;

}

Expression::Ptr NodeComparison::compress(const StaticContext::Ptr &context)

{

    const Expression::Ptr me(PairContainer::compress(context));

    if(me != this)

    /* We're already rewritten. */

        return me;

    if(m_operand1->staticType()->cardinality().isEmpty() ||

       m_operand2->staticType()->cardinality().isEmpty())

    {

        // TODO issue a warning in the @p context saying that one of the operands

        // were empty, and that the expression always result in the empty sequence

        // (which never is the intent, right?).

        return EmptySequence::create(this, context);

    }

    return Expression::Ptr(this);

}

QString NodeComparison::displayName(const QXmlNodeModelIndex::DocumentOrder op)

{

    switch(op)

    {

        case QXmlNodeModelIndex::Is:

            return QLatin1String("is");

        case QXmlNodeModelIndex::Precedes:

            return QLatin1String("<<");

        default:

        {

            Q_ASSERT(op == QXmlNodeModelIndex::Follows);

            return QLatin1String(">>");

        }

    }

}

SequenceType::Ptr NodeComparison::staticType() const

{

    if(m_operand1->staticType()->cardinality().allowsEmpty() ||

       m_operand2->staticType()->cardinality().allowsEmpty())

        return CommonSequenceTypes::ZeroOrOneBoolean;

    else

        return CommonSequenceTypes::ExactlyOneBoolean;

}

QXmlNodeModelIndex::DocumentOrder NodeComparison::operatorID() const

{

    return m_op;

}

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

{

    return visitor->visit(this);

}

QT_END_NAMESPACE