FastJet3.h

// FastJet3.h is a part of the PYTHIA event generator.
// Copyright (C) 2020 Torbjorn Sjostrand.
// PYTHIA is licenced under the GNU GPL v2 or later, see COPYING for details.
// Please respect the MCnet Guidelines, see GUIDELINES for details.

// This header file written by Gavin Salam.

#ifndef Pythia8_FastJet3_H
#define Pythia8_FastJet3_H

//----------------------------------------------------------------------
// ----------------------------------------------------------------------
// Copyright 2011 by Matteo Cacciari, Gavin Salam and Gregory
// Soyez. Permission is granted to redistribute this file and modify
// it, as long as this notice is retained and any changes are clearly
// marked. No warranties are provided!
// ----------------------------------------------------------------------

#include "fastjet/config.h"             // will allow a test for FJ3
#include "fastjet/ClusterSequence.hh"   // also gives PseudoJet & JetDefinition
#include "fastjet/Selector.hh"
#include "Pythia8/Event.h"              // this is what we need from Pythia8

// FASTJET_VERSION is only defined from version 3 onwards so we can
// use it to test that we have a sufficiently recent version
#ifndef FASTJET_VERSION
#error "FastJet3 is required in order to obtain the features of this interface"
#endif

FASTJET_BEGIN_NAMESPACE // place the code here inside the FJ namespace

class Py8Particle: public Pythia8::Particle,
                   public PseudoJet::UserInfoBase {
public:
  Py8Particle(const Pythia8::Particle & particle) : Particle(particle),
    mIndex(particle.index()) {}
   virtual int index() const override {return mIndex;}
private:
  int mIndex;
};

template<>
inline PseudoJet::PseudoJet(const Pythia8::Particle & particle) {
  reset(particle.px(),particle.py(),particle.pz(), particle.e());
  set_user_index( particle.index() );
  set_user_info(new Py8Particle(particle));
}

template<>
inline PseudoJet::PseudoJet(const Pythia8::Vec4 & particle) {
  reset(particle.px(),particle.py(),particle.pz(), particle.e());
}


template<class T> class SelectorWorkerPy8 : public SelectorWorker {
public:
  typedef  T (Pythia8::Particle::*Py8ParticleFnPtr)() const;

  SelectorWorkerPy8(Py8ParticleFnPtr member_fn_ptr, T value) :
    _member_fn_ptr(member_fn_ptr), _value(value) {};

  bool pass(const PseudoJet & p) const {
    const Pythia8::Particle * py8_particle
      = dynamic_cast<const Pythia8::Particle *>(p.user_info_ptr());
    if (py8_particle == 0) {
      return false; // no info, so false
    } else {
      return (py8_particle->*_member_fn_ptr)() == _value;
    }
  }
private:
  Py8ParticleFnPtr _member_fn_ptr;
  T _value;
};

inline Selector SelectorIsFinal    () {return
  Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isFinal   , true));}
inline Selector SelectorIsCharged  () {return
  Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isCharged , true));}
inline Selector SelectorIsNeutral  () {return
  Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isNeutral , true));}
inline Selector SelectorIsResonance() {return
  Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isResonance,true));}
inline Selector SelectorIsVisible  () {return
  Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isVisible , true));}
inline Selector SelectorIsLepton   () {return
  Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isLepton  , true));}
inline Selector SelectorIsQuark    () {return
  Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isQuark   , true));}
inline Selector SelectorIsGluon    () {return
  Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isGluon   , true));}
inline Selector SelectorIsDiquark  () {return
  Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isDiquark , true));}
inline Selector SelectorIsParton   () {return
  Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isParton  , true));}
inline Selector SelectorIsHadron   () {return
  Selector(new SelectorWorkerPy8<bool>(&Pythia8::Particle::isHadron  , true));}

inline Selector SelectorId       (int i) {return
  Selector(new SelectorWorkerPy8<int>(&Pythia8::Particle::id       , i));}
inline Selector SelectorIdAbs    (int i) {return
  Selector(new SelectorWorkerPy8<int>(&Pythia8::Particle::idAbs    , i));}
inline Selector SelectorStatus   (int i) {return
  Selector(new SelectorWorkerPy8<int>(&Pythia8::Particle::status   , i));}
inline Selector SelectorStatusAbs(int i) {return
  Selector(new SelectorWorkerPy8<int>(&Pythia8::Particle::statusAbs, i));}


FASTJET_END_NAMESPACE

#endif // Pythia8_FastJet3_H