ParticleListHelper.h

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
#pragma once
 
#include <framework/datastore/StoreObjPtr.h>
#include <framework/datastore/StoreArray.h>
#include <analysis/dataobjects/Particle.h>
#include <analysis/dataobjects/ParticleList.h>
 
#include <string>
#include <optional>
 
namespace Belle2 {
  class DecayDescriptor;

  class ParticleListHelper {
  public:
    ParticleListHelper() = default;
    explicit ParticleListHelper(const std::string& listname, bool save = true): ParticleListHelper()
    {
      registerList(listname, save);
    }

    void registerList(const std::string& listname, bool save = true);
    void registerList(const DecayDescriptor& decay, bool save = true);
    int getPDGCode() const { return m_pdg; }
    bool isSelfConjugated() const { return not m_antiList.has_value(); }
    void create();

    template<class ...Args> Particle& add(Args&& ... args)
    {
      auto index = m_particles.getEntries();
      // cppcheck doesn't seem to understand the forwarding of arguments and
      // throws an erroneous warning about reassigning appendNew
      //
      // cppcheck-suppress redundantAssignment
      // cppcheck-suppress redundantInitialization
      auto particle = m_particles.appendNew(std::forward<Args>(args)...);
      m_list->addParticle(index, particle->getPDGCode(), particle->getFlavorType());
      return *particle;
    }

    Particle& addParticle(const Particle& particle) { return add(particle); }
    Particle& addParticle(const ROOT::Math::PxPyPzEVector& momentum, bool conjugated = false)
    {
      return add(momentum, m_pdg * ((conjugated and not isSelfConjugated()) ? -1 : 1));
    }
 
  private:
    StoreArray<Particle> m_particles;
    StoreObjPtr<ParticleList> m_list;
    std::optional<StoreObjPtr<ParticleList>> m_antiList;
    int m_pdg;
  };

}