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#include "qbuiltintypes_p.h"

#include "qcommonsequencetypes_p.h"

#include "qcommonvalues_p.h"

#include "qgenericsequencetype_p.h"

#include "qinteger_p.h"

#include "qliteral_p.h"

#include "qrangeiterator_p.h"

#include "qrangeexpression_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

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

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

{

}

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

{

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

    if(!s)

        return CommonValues::emptyIterator;

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

    if(!e)

        return CommonValues::emptyIterator;

    const xsInteger start = s.as<Numeric>()->toInteger();

    const xsInteger end = e.as<Numeric>()->toInteger();

    if(start > end)

        return CommonValues::emptyIterator;

    else if(start == end)

        return makeSingletonIterator(s);

    else

        return Item::Iterator::Ptr(new RangeIterator(start, RangeIterator::Forward, end));

}

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

{

    return m_operand1->evaluateSingleton(context);

}

SequenceType::List RangeExpression::expectedOperandTypes() const

{

    SequenceType::List result;

    result.append(CommonSequenceTypes::ZeroOrOneInteger);

    result.append(CommonSequenceTypes::ZeroOrOneInteger);

    return result;

}

SequenceType::Ptr RangeExpression::staticType() const

{

    /* This logic makes the Cardinality more specific. */

    Cardinality::Count from;

    bool hasFrom;

    if(m_operand1->is(IDIntegerValue))

    {

        from = m_operand1->as<Literal>()->item().as<Integer>()->toInteger();

        hasFrom = true;

    }

    else

    {

        hasFrom = false;

        from = 0;

    }

    /* We can't check whether to is -1 since maybe the user wrote -1. Hence

     * hasTo is required. */

    bool hasTo;

    Cardinality::Count to;

    if(m_operand2->is(IDIntegerValue))

    {

        const xsInteger asInt = m_operand2->as<Literal>()->item().as<Integer>()->toInteger();

        to = asInt;

        if(to == asInt)

            hasTo = true;

        else

        {

            /* Cardinality::Count is not the same as type xsInteger. We had overflow. */

            to = -1;

            hasTo = false;

        }

    }

    else

    {

        to = -1;

        hasTo = false;

    }

    if(hasTo && hasFrom)

    {

        if(from > to)

        {

            /* The query is incorrectly written, we'll evaluate to the empty sequence.

             * Just return what's correct. */

            return CommonSequenceTypes::ZeroOrMoreIntegers;

        }

        else

        {

            Cardinality::Count count = (to - from) + 1; /* + 1, since it's inclusive. */

            return makeGenericSequenceType(BuiltinTypes::xsInteger, Cardinality::fromExact(count));

        }

    }

    else

    {

        /* We can't do fromExact(from, -1) since the latter can evaluate to a value that actually is

         * lower than from, although that unfortunately is very unlikely. */

        return CommonSequenceTypes::ZeroOrMoreIntegers;

    }

}

Expression::Properties RangeExpression::properties() const

{

    return Expression::DisableElimination;

}

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

{

    return visitor->visit(this);

}

QT_END_NAMESPACE