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

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** this package.

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

#include "qcommonsequencetypes_p.h"

#include "qcommonvalues_p.h"

#include "qitemmappingiterator_p.h"

#include "qpatternistlocale_p.h"

#include "qtracefn_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

namespace QPatternist

{

    /**

     * @short TraceCallback is a MappingCallback and takes care of

     * the tracing of each individual item.

     *

     * Because Patternist must be thread safe, TraceFN creates a TraceCallback

     * each time the function is evaluated. In other words, TraceFN, which is

     * an Expression sub class, can't modify its members, but MappingCallback

     * does not have this limitation since it's created on a per evaluation basis.

     *

     * @author Frans Englich <frans.englich@nokia.com>

     */

    class TraceCallback : public QSharedData

    {

    public:

        typedef QExplicitlySharedDataPointer<TraceCallback> Ptr;

        inline TraceCallback(const QString &msg) : m_position(0),

                                                   m_msg(msg)

        {

        }

        /**

         * Performs the actual tracing.

         */

        Item mapToItem(const Item &item,

                            const DynamicContext::Ptr &context)

        {

            QTextStream out(stderr);

            ++m_position;

            if(m_position == 1)

            {

                if(item)

                {

                    out << qPrintable(m_msg)

                        << " : "

                        << qPrintable(item.stringValue());

                }

                else

                {

                    out << qPrintable(m_msg)

                        << " : ("

                        << qPrintable(formatType(context->namePool(), CommonSequenceTypes::Empty))

                        << ")\n";

                    return Item();

                }

            }

            else

            {

                out << qPrintable(item.stringValue())

                    << '['

                    << m_position

                    << "]\n";

            }

            return item;

        }

    private:

        xsInteger m_position;

        const QString m_msg;

    };

}

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

{

    const QString msg(m_operands.last()->evaluateSingleton(context).stringValue());

    return makeItemMappingIterator<Item>(TraceCallback::Ptr(new TraceCallback(msg)),

                                              m_operands.first()->evaluateSequence(context),

                                              context);

}

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

{

    const QString msg(m_operands.last()->evaluateSingleton(context).stringValue());

    const Item item(m_operands.first()->evaluateSingleton(context));

    return TraceCallback::Ptr(new TraceCallback(msg))->mapToItem(item, context);

}

SequenceType::Ptr TraceFN::staticType() const

{

    return m_operands.first()->staticType();

}

QT_END_NAMESPACE