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//

//  W A R N I N G

//  -------------

//

// This file is not part of the Qt API.  It exists purely as an

// implementation detail.  This header file may change from version to

// version without notice, or even be removed.

//

// We mean it.

#ifndef Patternist_CastAs_H

#define Patternist_CastAs_H

#include "qsinglecontainer_p.h"

#include "qcastingplatform_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist

{

    /**

     * @short Implements XPath 2.0's <tt>cast as</tt> expression.

     *

     * Implements the casting expression, such as <tt>'3' cast as xs:integer</tt>. This class also

     * implements constructor functions, which are created in the ConstructorFunctionsFactory.

     *

     * CastAs uses CastingPlatform for carrying out the actual casting.

     *

     * @see <a href="http://www.w3.org/TR/xpath-functions/#casting">XQuery 1.0

     * and XPath 2.0 Functions and Operators, 7 Casting</a>

     * @see <a href="http://www.w3.org/TR/xpath20/#id-cast">XML Path Language

     * (XPath) 2.0, 3.10.2 Cast</a>

     * @author Frans Englich <frans.englich@nokia.com>

     * @ingroup Patternist_expressions

     */

    class CastAs : public SingleContainer,

                   public CastingPlatform<CastAs, true /* issueError */>

    {

    public:

        /**

         * @todo Wrong/old documentation

         *

         * Creates a cast expression for the type @p name via the schema type

         * factory @p factory. This function is used by parser when creating

         * 'cast to' expressions, and the ConstructorFunctionsFactory, when creating

         * constructor functions.

         *

         * @param targetType the type which the CastAs should cast to

         * @param source the operand to evaluate and then cast from

         */

        CastAs(const Expression::Ptr &source,

               const SequenceType::Ptr &targetType);

        virtual Item evaluateSingleton(const DynamicContext::Ptr &) const;

        virtual SequenceType::List expectedOperandTypes() const;

        /**

         * @returns a SequenceType where the ItemType is this CastAs's

         * target type, as per targetType(), and the Cardinality is inferred from the

         * source operand to reflect whether this CastAs always will evaluate to

         * exactly-one or zero-or-one values.

         */

        virtual SequenceType::Ptr staticType() const;

        /**

         * Overridden in order to check that casting to an abstract type

         * is not attempted.

         */

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

                                          const SequenceType::Ptr &reqType);

        /**

         * If the target type is the same as the source type, it is rewritten

         * to the operand.

         */

        virtual Expression::Ptr compress(const StaticContext::Ptr &context);

        virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;

        inline ItemType::Ptr targetType() const

        {

            return m_targetType->itemType();

        }

        inline SequenceType::Ptr targetSequenceType() const

        {

            return m_targetType;

        }

    private:

        /**

         * Performs casting to @c xs:QName. This case is special, and is always done at compile time.

         */

        Expression::Ptr castToQName(const StaticContext::Ptr &context) const;

        const SequenceType::Ptr m_targetType;

    };

}

QT_END_NAMESPACE

QT_END_HEADER

#endif