source: trunk/src/xmlpatterns/expr/qforclause.cpp@ 197

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#include "qcommonsequencetypes_p.h"
#include "qemptysequence_p.h"
#include "qgenericsequencetype_p.h"
#include "qitemmappingiterator_p.h"
#include "qoptimizationpasses_p.h"
#include "qsequencemappingiterator_p.h"

#include "qforclause_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

ForClause::ForClause(const VariableSlotID varSlot,
                     const Expression::Ptr &bindingSequence,
                     const Expression::Ptr &returnExpression,
                     const VariableSlotID positionSlot) : PairContainer(bindingSequence, returnExpression),
                                                          m_varSlot(varSlot),
                                                          m_positionSlot(positionSlot),
                                                          m_allowsMany(true)
{
    Q_ASSERT(m_positionSlot > -2);
}

Item ForClause::mapToItem(const Item &item,
                          const DynamicContext::Ptr &context) const
{
    context->setRangeVariable(m_varSlot, item);
    return m_operand2->evaluateSingleton(context);
}

Item::Iterator::Ptr ForClause::mapToSequence(const Item &item,
                                             const DynamicContext::Ptr &context) const
{
    context->setRangeVariable(m_varSlot, item);
    return m_operand2->evaluateSequence(context);
}

void ForClause::riggPositionalVariable(const DynamicContext::Ptr &context,
                                       const Item::Iterator::Ptr &source) const
{
    if(m_positionSlot > -1)
        context->setPositionIterator(m_positionSlot, source);
}

Item::Iterator::Ptr ForClause::evaluateSequence(const DynamicContext::Ptr &context) const
{
    const Item::Iterator::Ptr source(m_operand1->evaluateSequence(context));

    riggPositionalVariable(context, source);

    if(m_allowsMany)
    {
        return makeSequenceMappingIterator<Item>(ConstPtr(this),
                                                 source,
                                                 context);
    }
    else
    {
        return makeItemMappingIterator<Item>(ConstPtr(this),
                                             source,
                                             context);
    }
}

Item ForClause::evaluateSingleton(const DynamicContext::Ptr &context) const
{
    return evaluateSequence(context)->next();
}

void ForClause::evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const
{
    Item::Iterator::Ptr it;
    const Item::Iterator::Ptr source(m_operand1->evaluateSequence(context));

    riggPositionalVariable(context, source);

    Item next(source->next());

    while(next)
    {
        context->setRangeVariable(m_varSlot, next);
        m_operand2->evaluateToSequenceReceiver(context);
        next = source->next();
    }
}

Expression::Ptr ForClause::typeCheck(const StaticContext::Ptr &context,
                                     const SequenceType::Ptr &reqType)
{
    const Expression::Ptr me(PairContainer::typeCheck(context, reqType));
    const Cardinality card(m_operand1->staticType()->cardinality());

    /* If our source is empty we will always evaluate to the empty sequence, so rewrite. */
    if(card.isEmpty())
        return EmptySequence::create(this, context);
    else