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#include "qboolean_p.h"

#include "qcommonsequencetypes_p.h"

#include "qdynamiccontextstore_p.h"

#include "qliteral_p.h"

#include "qletclause_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

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

                     const Expression::Ptr &operand2,

                     const VariableDeclaration::Ptr &decl) : PairContainer(operand1, operand2)

                                                           , m_varDecl(decl)

{

    Q_ASSERT(m_varDecl);

}

DynamicContext::Ptr LetClause::bindVariable(const DynamicContext::Ptr &context) const

{

    context->setExpressionVariable(m_varDecl->slot, Expression::Ptr(new DynamicContextStore(m_operand1, context)));

    return context;

}

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

{

    return m_operand2->evaluateSequence(bindVariable(context));

}

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

{

    return m_operand2->evaluateSingleton(bindVariable(context));

}

bool LetClause::evaluateEBV(const DynamicContext::Ptr &context) const

{

    return m_operand2->evaluateEBV(bindVariable(context));

}

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

{

    m_operand2->evaluateToSequenceReceiver(bindVariable(context));

}

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

                                     const SequenceType::Ptr &reqType)

{

    /* Consider the following query:

     *

     * <tt>let $d := \<child type=""/>

     * return $d//\*[let $i := @type

     *              return $d//\*[$i]]</tt>

     *

     * The node test <tt>@type</tt> is referenced from two different places,

     * where each reference have a different focus. So, in the case of that the source

     * uses the focus, we need to use a DynamicContextStore to ensure the variable

     * is always evaluated with the correct focus, regardless of where it is referenced

     * from.

     *

     * We miss out a lot of false positives. For instance, the case of where the focus

     * is identical for everyone. One reason we cannot check this, is that Expression

     * doesn't know about its parent.

     */

    m_varDecl->canSourceRewrite = !m_operand1->deepProperties().testFlag(RequiresFocus);

    if(m_varDecl->canSourceRewrite)

        return m_operand2->typeCheck(context, reqType);

    else

        return PairContainer::typeCheck(context, reqType);

}

Expression::Properties LetClause::properties() const

{

    return m_varDecl->expression()->properties() & (Expression::RequiresFocus | Expression::IsEvaluated | Expression::DisableElimination);

}

SequenceType::List LetClause::expectedOperandTypes() const

{

    SequenceType::List result;

    result.append(CommonSequenceTypes::ZeroOrMoreItems);

    result.append(CommonSequenceTypes::ZeroOrMoreItems);

    return result;

}

SequenceType::Ptr LetClause::staticType() const

{

    return m_operand2->staticType();

}

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

{

    return visitor->visit(this);

}

Expression::ID LetClause::id() const

{

    return IDLetClause;

}

QT_END_NAMESPACE