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#include "qdocumentprojector_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

DocumentProjector::DocumentProjector(const ProjectedExpression::Vector &paths,

                                     QAbstractXmlReceiver *const receiver) : m_paths(paths)

                                                                           , m_pathCount(paths.count())

                                                                           , m_action(ProjectedExpression::Move)

                                                                           , m_nodesInProcess(0)

                                                                           , m_receiver(receiver)

{

    Q_ASSERT_X(paths.count() > 0, Q_FUNC_INFO,

               "Using DocumentProjector with no paths is an "

               "overhead and has also undefined behavior.");

    Q_ASSERT(m_receiver);

}

void DocumentProjector::startElement(const QXmlName name)

{

    Q_UNUSED(name);

    switch(m_action)

    {

        case ProjectedExpression::KeepSubtree:

        {

            m_receiver->startElement(name);

            /* Fallthrough. */

        }

        case ProjectedExpression::Skip:

        {

            ++m_nodesInProcess;

            return;

        }

        default:

        {

            Q_ASSERT_X(m_action == ProjectedExpression::Move, Q_FUNC_INFO,

                       "We're not supposed to receive Keep here, because "

                       "endElement() should always end that state.");

            for(int i = 0; i < m_pathCount; ++i)

            {

                m_action = m_paths.at(i)->actionForElement(name, m_paths[i]);

                switch(m_action)

                {

                    case ProjectedExpression::Keep:

                    {

                        m_action = ProjectedExpression::Keep;

                        continue;

                    }

                    case ProjectedExpression::KeepSubtree:

                    {

                        /* Ok, at least one path wanted this node. Pass it on,

                         * and exit. */

                        m_receiver->startElement(name);

                        ++m_nodesInProcess;

                        return;

                    }

                    case ProjectedExpression::Skip:

                    {

                        /* This particular path doesn't need it, but

                         * some other path might, so continue looping. */

                        continue;

                    }

                    case ProjectedExpression::Move:

                        Q_ASSERT_X(false, Q_FUNC_INFO, "The action functions can never return Move.");

                }

            }

            ++m_nodesInProcess;

            if(m_action == ProjectedExpression::Keep)

                m_receiver->startElement(name);

            else

            {

                Q_ASSERT(m_action == ProjectedExpression::Skip);

            }

        }

    }

}

void DocumentProjector::endElement()

{

    if(m_action == ProjectedExpression::Keep)

    {

        Q_ASSERT(m_nodesInProcess == 1);

        m_receiver->endElement();

        /* We have now kept the single node, and now wants to skip

         * all its children. */

        m_action = ProjectedExpression::Skip;

        m_nodesInProcess = 0;

    }

    else if(m_action == ProjectedExpression::KeepSubtree)

    {

        m_receiver->endElement();

        --m_nodesInProcess;

        if(m_nodesInProcess == 0)

        {

            /* We have now skipped all the children, let's do

             * a new path analysis. */

            m_action = ProjectedExpression::Move;

        }

    }

    else

    {

        Q_ASSERT_X(m_action == ProjectedExpression::Skip, Q_FUNC_INFO,

                   "We're not supposed to be in a Move action here.");

        /* We skip calling m_receiver's endElement() here since we're

         * skipping. */

        Q_ASSERT(m_nodesInProcess > 0);

        --m_nodesInProcess;

        if(m_nodesInProcess == 0)

        {

            /* Ok, we've skipped them all, let's do something

             * new -- let's Move on to the next path! */

            m_action = ProjectedExpression::Move;

        }

    }

}

void DocumentProjector::attribute(const QXmlName name,

                                  const QString &value)

{

    Q_UNUSED(name);

    Q_UNUSED(value);

}

void DocumentProjector::namespaceBinding(const QXmlName nb)

{

    Q_UNUSED(nb);

}

void DocumentProjector::comment(const QString &value)

{

    Q_ASSERT_X(!value.contains(QLatin1String("--")), Q_FUNC_INFO,

               "Invalid input; it's the caller's responsibility to ensure the input is correct.");

    Q_UNUSED(value);

}

void DocumentProjector::characters(const QString &value)

{

    Q_UNUSED(value);

}

void DocumentProjector::processingInstruction(const QXmlName name,

                                              const QString &value)

{

    Q_ASSERT_X(!value.contains(QLatin1String("?>")), Q_FUNC_INFO,

               "Invalid input; it's the caller's responsibility to ensure the input is correct.");

    Q_UNUSED(name);

    Q_UNUSED(value);

}

void DocumentProjector::item(const Item &outputItem)

{

    Q_UNUSED(outputItem);

}

void DocumentProjector::startDocument()

{

}

void DocumentProjector::endDocument()

{

}

QT_END_NAMESPACE