mirrorextender.h

// Description: Mirroring index extender
// Documentation: indexextenders.txt

#ifndef PASTELSYS_MIRROREXTENDER_H
#define PASTELSYS_MIRROREXTENDER_H

#include "pastel/sys/extender/indexextender.h"

namespace Pastel
{

    class MirrorExtender
        : public IndexExtender
    {
    public:
        virtual ~MirrorExtender()
        {
        }

        virtual integer operator()(
            integer index, integer extent) const
        {
            // -1 => 1
            // extent => extent - 2

            const integer doubleExtent = 2 * extent;

            integer newIndex =
                mod(index, doubleExtent - 1);

            if (newIndex >= extent)
            {
                newIndex = (doubleExtent - 1) - newIndex;
            }

            return newIndex;
        }
    };

    using MirrorExtenderPtr = CountedPtr<MirrorExtender>;
    using ConstMirrorExtenderPtr = CountedPtr<const MirrorExtender>;

    inline MirrorExtenderPtr mirrorExtender()
    {
        return MirrorExtenderPtr(new MirrorExtender);
    }

}

#endif