Constraint.h

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//****************************************************************************
//*                   This file is part of PandaRoot.                        *
//*                                                                          *
//*            PandaRoot is distributed under the terms of the               *
//*              GNU General Public License (GPL) version 3,                 *
//*                 copied verbatim in the file "LICENSE".                   *
//*                                                                          *
//*  Copyright (C) 2006 - 2024 FAIR GmbH and copyright holders of PandaRoot  *
//*     The copyright holders are listed in the file "COPYRIGHTHOLDERS".     *
//*               The authors are listed in the file "AUTHORS".              *
//****************************************************************************

// ******************************************************
// DecayTreeFitter Package
// We thank the original author Wouter Hulsbergen
// (BaBar, LHCb) for providing the sources.
// http://arxiv.org/abs/physics/0503191v1 (2005)
// Adaptation & Development for PANDA: Ralf Kliemt (2015)
// ******************************************************
#ifndef DECAYTREEFITTER_CONSTRAINT_H
#define DECAYTREEFITTER_CONSTRAINT_H 1

#include <string>
#include <iostream>
#include "ErrCode.h"
#include "Rtypes.h"

namespace DecayTreeFitter {
class ParticleBase;
class Projection;
class FitParams;

class Constraint {
 public:
  // the order of these constraints is important: it is the order in
  // which they are applied.

  enum Type { unknown = 0, beamspot, lifetime, resonance, composite, track, photon, conversion, kinematic, massEnergy, geometric, mass, beamenergy, merged, ntypes };

  bool operator<(const Constraint &rhs) const;

  bool operator==(const Constraint &rhs) const { return m_type == rhs.m_type; }

  // accessors
  Type type() const { return m_type; }
  unsigned int dim() const { return m_dim; }
  bool isLineair() const { return m_maxNIter <= 1; }
  unsigned int nIter() const { return m_maxNIter; }

  Constraint() : m_node(nullptr), m_depth(0), m_type(unknown), m_dim(0) {}

  Constraint(const ParticleBase *node, Type atype, int depth, unsigned int adim, int maxniter = 1 /*, double precision=1e-5*/)
    : m_node(node), m_depth(depth), m_type(atype), m_dim(adim), m_weight(1), m_maxNIter(maxniter)
  {
  }

  virtual ~Constraint() {}

  virtual ErrCode project(const FitParams *fitpar, Projection &p) const;
  virtual ErrCode filter(FitParams *fitpar) const;
  virtual ErrCode filter(FitParams *fitpar, const FitParams *reference) const;
  virtual void print(std::ostream &os = std::cout) const;
  std::string name() const;

  // set to minus one if constraints needs to be removed on next filter
  void setWeight(int w) { m_weight = w < 0 ? -1 : 1; }

 protected:
  Constraint(Constraint::Type atype) : m_node(nullptr), m_depth(0), m_type(atype), m_dim(0), m_weight(0), m_maxNIter(0) {}
  void setDim(unsigned int d) { m_dim = d; }
  void setNIter(unsigned int d) { m_maxNIter = d; }

 private:
  const ParticleBase *m_node;
  int m_depth;
  Type m_type;
  unsigned int m_dim;
  // the weight: guassian constraint can be 'unfilter'
  int m_weight;
  int m_maxNIter; // maximum number of iterations for non-linear constraints
  ClassDef(Constraint, 1)
};

} // namespace DecayTreeFitter

#endif