Propagator.h

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#ifndef CommonDet_Propagator_H
#define CommonDet_Propagator_H

#include "DataFormats/TrajectorySeed/interface/PropagationDirection.h"
#include "TrackingTools/TrajectoryState/interface/FreeTrajectoryState.h"
#include "TrackingTools/TrajectoryState/interface/TrajectoryStateOnSurface.h"

#include <utility>
#include <memory>

class Plane;
class Cylinder;
class Surface;
class MagneticField;

namespace reco {
  class BeamSpot;
}

class Propagator {
public:
  explicit Propagator(PropagationDirection dir = alongMomentum) : theDir(dir) {}
  virtual ~Propagator();

  template <typename STA, typename SUR>
  TrajectoryStateOnSurface propagate(STA const& state, SUR const& surface) const {
    return propagateWithPath(state, surface).first;
  }

public:
  virtual std::pair<TrajectoryStateOnSurface, double> propagateWithPath(const FreeTrajectoryState&,
                                                                        const Surface&) const final;

  virtual std::pair<TrajectoryStateOnSurface, double> propagateWithPath(const FreeTrajectoryState&,
                                                                        const Plane&) const = 0;

  virtual std::pair<TrajectoryStateOnSurface, double> propagateWithPath(const FreeTrajectoryState&,
                                                                        const Cylinder&) const = 0;

  virtual std::pair<TrajectoryStateOnSurface, double> propagateWithPath(const TrajectoryStateOnSurface& tsos,
                                                                        const Surface& sur) const final;

  virtual std::pair<TrajectoryStateOnSurface, double> propagateWithPath(const TrajectoryStateOnSurface& tsos,
                                                                        const Plane& sur) const {
    return propagateWithPath(*tsos.freeState(), sur);
  }

  virtual std::pair<TrajectoryStateOnSurface, double> propagateWithPath(const TrajectoryStateOnSurface& tsos,
                                                                        const Cylinder& sur) const {
    return propagateWithPath(*tsos.freeState(), sur);
  }

  virtual std::pair<FreeTrajectoryState, double> propagateWithPath(const FreeTrajectoryState& ftsStart,
                                                                   const GlobalPoint& pDest) const;
  virtual std::pair<FreeTrajectoryState, double> propagateWithPath(const FreeTrajectoryState& ftsStart,
                                                                   const GlobalPoint& pDest1,
                                                                   const GlobalPoint& pDest2) const;
  virtual std::pair<FreeTrajectoryState, double> propagateWithPath(const FreeTrajectoryState& ftsStart,
                                                                   const reco::BeamSpot& beamSpot) const;

  // this is a mess...
  virtual FreeTrajectoryState propagate(const FreeTrajectoryState& ftsStart, const GlobalPoint& pDest) const final {
    return propagateWithPath(ftsStart, pDest).first;
  }
  virtual FreeTrajectoryState propagate(const FreeTrajectoryState& ftsStart,
                                        const GlobalPoint& pDest1,
                                        const GlobalPoint& pDest2) const final {
    return propagateWithPath(ftsStart, pDest1, pDest2).first;
  }
  virtual FreeTrajectoryState propagate(const FreeTrajectoryState& ftsStart,
                                        const reco::BeamSpot& beamSpot) const final {
    return propagateWithPath(ftsStart, beamSpot).first;
  }

public:
  virtual void setPropagationDirection(PropagationDirection dir) { theDir = dir; }

  virtual PropagationDirection propagationDirection() const final { return theDir; }

  virtual bool setMaxDirectionChange(float phiMax) { return false; }

  virtual Propagator* clone() const = 0;

  virtual const MagneticField* magneticField() const = 0;

private:
  PropagationDirection theDir;
};

// Put here declaration of helper function, so that it is
// automatically included in all proper places w/o having to add an
// additional include file. Keep implementation separate, to avoid
// multiple definition of the same symbol in all cc inlcuding this
// file.
std::unique_ptr<Propagator> SetPropagationDirection(Propagator const& iprop, PropagationDirection dir);

#endif  // CommonDet_Propagator_H