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

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#include "qbuiltintypes_p.h"

#include "qcommonsequencetypes_p.h"

#include "qgenericsequencetype_p.h"

#include "qnodesort_p.h"

#include "qpatternistlocale_p.h"

#include "qsequencemappingiterator_p.h"

#include "qtypechecker_p.h"

#include "qpath_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

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

           const Expression::Ptr &operand2,

           const Kind kind) : PairContainer(operand1, operand2)

                            , m_hasCreatedSorter(kind != RegularPath)

                            , m_isLast(false)

                            , m_checkXPTY0018(kind == RegularPath)

                            , m_kind(kind)

{

}

Item::Iterator::Ptr Path::mapToSequence(const Item &item,

                                        const DynamicContext::Ptr &context) const

{

    /* item is the focus here. That is in <e/>/1, item is <e/>. However,

     * we don't use it, since the context item is accessed through

     * DynamicContext::focusIterator() and friends. */

    Q_ASSERT(item);

    Q_UNUSED(item); /* Needed when compiling in release mode. */

    return m_operand2->evaluateSequence(context);

}

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

{

    /* Note, we use the old context for m_operand1. */

    const Item::Iterator::Ptr source(m_operand1->evaluateSequence(context));

    const DynamicContext::Ptr focus(context->createFocus());

    focus->setFocusIterator(source);

    const Item::Iterator::Ptr result(makeSequenceMappingIterator<Item>(ConstPtr(this), source, focus));

    if(m_checkXPTY0018)

    {

        /* This is an expensive code path, but it should happen very rarely. */

        enum FoundItem

        {

            FoundNone,

            FoundNode,

            FoundAtomicValue

        } hasFound = FoundNone;

        Item::List whenChecked;

        Item next(result->next());

        while(next)

        {

            const FoundItem found = next.isAtomicValue() ? FoundAtomicValue : FoundNode;

            if(hasFound != FoundNone && hasFound != found)

            {

                /* It's an atomic value and we've already found a node. Mixed content. */

                context->error(QtXmlPatterns::tr("The last step in a path must contain either nodes "

                                                 "or atomic values. It cannot be a mixture between the two."),

                               ReportContext::XPTY0018, this);

            }

            else

                hasFound = found;

            whenChecked.append(next);

            next = result->next();

        }

        return makeListIterator(whenChecked);

    }

    else

        return result;

}

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

{

    /* This function is called if both operands' cardinality is exactly-one. Therefore

     * we manually go forward in the focus by calling next().

     *

     * We don't check for XPTY0018, only in evaluateSequence(), since if we're guaranteed

     * to evaluate to one item, we can only evaluate to one node or one atomic value.

     */

    /* Note, we use the old context for m_operand1. */

    const Item::Iterator::Ptr source(m_operand1->evaluateSequence(context));

    const DynamicContext::Ptr focus(context->createFocus());

    focus->setFocusIterator(source);

    /* This test is needed because if the focus is empty, we don't want to(nor can't) evaluate

     * the next step. */

    // TODO Why are we at all invoked then?

    if(source->next())

        return m_operand2->evaluateSingleton(focus);

    else

        return Item();

}

void Path::evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const

{

    /* Note, we use the old context for m_operand1. */

    const Item::Iterator::Ptr source(m_operand1->evaluateSequence(context));

    const DynamicContext::Ptr focus(context->createFocus());

    focus->setFocusIterator(source);

    while(source->next())

        m_operand2->evaluateToSequenceReceiver(focus);

}

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

{

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

    /* "./expr" is by now equal to "expr" since we've done

     * focus/type checks, and a node sorter has been inserted. */

    if(m_operand1->is(IDContextItem))

        return m_operand2;

    /* We do this as late as we can, such that we pick up the most recent type

     * from the operand. */

    if(m_isLast && m_kind != XSLTForEach && m_operand2->staticType()->itemType() == BuiltinTypes::item)

        m_checkXPTY0018 = true;

    return me;

}

Expression::Ptr Path::typeCheck(const StaticContext::Ptr &context,

                                const SequenceType::Ptr &reqType)

{

    m_operand2->announceFocusType(newFocusType());

    /* Here we apply the function conversion first, and with the error code

     * that we want -- XPTY0019 instead of XPTY0004. Unfortunately

     * PairContainer::typeCheck() will do the type check again, which is

     * redundant in the case of when we're not XSLTForEach.

     *

     * If we're XSLTForEach, it means we're a synthetic "map" expression for

     * implementing various XSL-T expressions, and hence don't have the

     * constraint of XPTY0019.

     *

     * It's important that typeCheck() is run for the operands(of course), and the call to

     * PairContainer::typeCheck() ensures that below, in the case that we're XSL-T code.

     *

     * The type we expect, CommonSequenceTypes::ZeroOrMoreNodes() needs to be in sync with

     * what we return in expectedOperandTypes(). */

    if(m_kind != XSLTForEach)

    {

        m_operand1 = TypeChecker::applyFunctionConversion(m_operand1,

                                                          CommonSequenceTypes::ZeroOrMoreNodes,

                                                          context,

                                                          m_kind == ForApplyTemplate ? ReportContext::XTTE0520

                                                                                     : ReportContext::XPTY0019);

    }

    /* If our step ends with atomic values, we cannot sort.

     *

     * We must smack the NodeSortExpression ontop before calling typeCheck(), since the latter

     * may insert an Atomizer, as possibly mandated by reqType. By doing it after, the Atomizer

     * will be a parent to NodeSortExpression, as opposed to a child.

     */

    if(!m_hasCreatedSorter)

    {

        m_hasCreatedSorter = true;

        return NodeSortExpression::wrapAround(Expression::Ptr(this), context)->typeCheck(context, reqType);

    }

    else

        return PairContainer::typeCheck(context, reqType);

}

SequenceType::List Path::expectedOperandTypes() const

{

    SequenceType::List result;

    /* This value needs to be in sync with what we pass to

     * applyFunctionConversion() in typeCheck() above.

     *

     * We don't have the XPTY0019 restriction when we're synthetic XSL-T code.

     */

    if(m_kind == XSLTForEach)

        result.append(CommonSequenceTypes::ZeroOrMoreItems);

    else

        result.append(CommonSequenceTypes::ZeroOrMoreNodes);

    result.append(CommonSequenceTypes::ZeroOrMoreItems);

    return result;

}

SequenceType::Ptr Path::staticType() const

{

    const SequenceType::Ptr opType(m_operand2->staticType());

    /* For each parent step, we evaluate the child step. So multiply the two

     * cardinalities. */

    return makeGenericSequenceType(opType->itemType(),

                                   m_operand1->staticType()->cardinality() * opType->cardinality());

}

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

{

    return visitor->visit(this);

}

Expression::Properties Path::properties() const

{

    return CreatesFocusForLast | ((m_operand1->properties() | m_operand2->properties()) & (RequiresCurrentItem | DisableElimination));

}

ItemType::Ptr Path::newFocusType() const

{

    return m_operand1->staticType()->itemType();

}

Expression::ID Path::id() const

{

    return IDPath;

}

QT_END_NAMESPACE