CandCommonVertexFitter.h

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#ifndef RecoCandUtils_CandCommonVertexFitter_h
#define RecoCandUtils_CandCommonVertexFitter_h
/* \class CandCommonVertexFitter
 *
 * \author Luca Lista, INFN
 *
 */

#include "FWCore/ParameterSet/interface/ParameterSetfwd.h"
#include "TrackingTools/TransientTrack/interface/TransientTrack.h"
#include "RecoVertex/VertexPrimitives/interface/TransientVertex.h"
#include "DataFormats/RecoCandidate/interface/RecoCandidate.h"
#include <vector>
class MagneticField;
namespace reco { class VertexCompositeCandidate; }

class CandCommonVertexFitterBase {
public:
  typedef reco::Vertex::CovarianceMatrix CovarianceMatrix;
  CandCommonVertexFitterBase(const edm::ParameterSet &) : bField_(nullptr) { }
  virtual ~CandCommonVertexFitterBase() { }
  void set(const MagneticField * bField) { bField_ = bField; }
  void set(reco::VertexCompositeCandidate &) const;
  
protected:
  const MagneticField * bField_;
  void fill(std::vector<reco::TransientTrack> &, 
        std::vector<reco::Candidate *> &,
        std::vector<reco::RecoCandidate::TrackType> &,
        reco::Candidate &) const;
  virtual bool fit(TransientVertex &, 
           const std::vector<reco::TransientTrack> &) const = 0;
  mutable double chi2_;
  mutable double ndof_;
  mutable CovarianceMatrix cov_;
};

#include "PhysicsTools/UtilAlgos/interface/ParameterAdapter.h"

template<typename Fitter>
class CandCommonVertexFitter : public CandCommonVertexFitterBase {
public:
  CandCommonVertexFitter(const edm::ParameterSet & cfg) : 
    CandCommonVertexFitterBase(cfg),
    fitter_(reco::modules::make<Fitter>(cfg)) { 
  }
  bool fit(TransientVertex & vertex, 
       const std::vector<reco::TransientTrack> & tracks) const override {
    try {
      vertex = fitter_.vertex(tracks);
    } catch (std::exception & err) {
      std::cerr << ">>> exception thrown by KalmanVertexFitter:\n"
        << err.what() << "\n"
        << ">>> candidate not fitted to common vertex" << std::endl;
      return false;
    }
    return vertex.isValid();
  }
private:
  Fitter fitter_;
};

#endif