// PropNull.h

#ifndef PropNull_H
#define PropNull_H

// This propagator does not modify the track.  It simple checks
// if the track surface matches the requested surface and, if so,
// returns success.
//

#include "Propagator.h"

namespace trf {

class PropNull : public Propagator {

public:  // static methods

  // Return the type name.
  static TypeName get_type_name() { return "PropNull"; }

  // Return the creator.
  static ObjCreator get_creator();

  // Return the type.
  static Type get_static_type() { return get_creator(); }

  // Output stream.
  void ostr(std::ostream& stream) const;

public:

  // constructor
  PropNull();

  // destructor
  ~PropNull();

  // Return the type.
  Type get_type() const { return get_static_type(); }

  // Write object data.
  ObjData write_data() const;

  // Clone, i.e. create a copy on the free store.
  Propagator* new_propagator() const;

  // propagate a track without error
  PropStat vec_prop(VTrack& trv, const Surface& srf,
                    TrackDerivative* pder =0) const;

  // propagate a track without error in the specified direction
  PropStat vec_dir_prop(VTrack& trv, const Surface& srf, PropDir dir,
                        TrackDerivative* pder =0) const;

  // propagate a track with error
  PropStat err_prop(ETrack& tre, const Surface& srf,
                    TrackDerivative* pder =0) const;

  // propagate a track with error in the specified direction
  PropStat err_dir_prop(ETrack& tre, const Surface& srf, PropDir dir,
                        TrackDerivative* pder =0) const;

};

}  // end namespace trf

#endif