source: trunk/src/xmlpatterns/expr/qliteral_p.h@ 763

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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_Literal_H
#define Patternist_Literal_H

#include "qemptycontainer_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist
{
    /**
     * @short Houses an AtomicValue, making it available as an Expression.
     *
     * This is not only literals that can be created via the XQuery syntax(strings and numbers), but
     * all other atomic values, such as <tt>xs:date</tt> or <tt>xs:time</tt>.
     *
     * @see <a href="http://www.w3.org/TR/xquery/#id-literals">XQuery 1.0: An XML Query Language,
     * 3.1.1 Literals</a>
     * @author Frans Englich <[email protected]>
     * @ingroup Patternist_expressions
     */
    class Literal : public EmptyContainer
    {
    public:
        /**
         * Creates a Literal that represents @p item.
         *
         * @param item must be non-null and cannot be a QXmlNodeModelIndex.
         */
        Literal(const Item &item);

        virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;
        virtual bool evaluateEBV(const DynamicContext::Ptr &context) const;
        void evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const;

        virtual SequenceType::Ptr staticType() const;
        virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;
        virtual ID id() const;
        virtual QString description() const;

        /**
         * @returns Expression::DisableElimination and Expression::IsEvaluated
         */
        virtual Properties properties() const;

        /**
         * Declaring the return value of this function a const reference, leads
         * to crashes in patternistview, for a to me unknown reason.
         */
        inline Item item() const
        {
            return m_item;
        }

    private:
        const Item m_item;
    };

    /**
     * @short Creates a Literal that wraps @p item, and returns it.
     *
     * This simplifies code. Instead of writing:
     *
     * @code
     * Expression::Ptr(new Literal(item));
     * @endcode
     *
     * One can write:
     *
     * @code
     * wrapLiteral(item);
     * @endcode
     *
     * This function is not declared static, because it breaks the build on
     * at least aix-xlc-64.
     *
     * @relates Literal
     */
    inline Expression::Ptr wrapLiteral(const Item &item,
                                       const StaticContext::Ptr &context,
                                       const SourceLocationReflection *const r)
    {
        Q_ASSERT(item);

        const Expression::Ptr retval(new Literal(item));
        context->addLocation(retval.data(), context->locationFor(r));

        return retval;
    }
}

QT_END_NAMESPACE

QT_END_HEADER

#endif