ElasticDecayUtil.h

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/*
  Copyright (C) 2002-2023 CERN for the benefit of the ATLAS collaboration
*/
 
#ifndef ELASTICDECAYUTIL_H
#define ELASTICDECAYUTIL_H 1
 
#include "xAODTruth/TruthParticle.h"
 
// for debugging
#include "CxxUtils/checker_macros.h"
#include <type_traits>
#include <initializer_list>
#include <mutex>
#include "ActsInterop/StatUtils.h"
 
// Empty struct emulating enough of the interface to be used as a dummy replacement for a Gaudi property
struct EmptyProperty {
   template <typename... T_Args>
   EmptyProperty(T_Args... ) {}
   // to match empty or some non-empty initializer list
   template <typename T_Arg1, typename T_Arg2, typename... T_Args>
   EmptyProperty(T_Arg1, T_Arg2, std::initializer_list<int> &&, T_Args... ) {}
   template <typename T_Arg1, typename T_Arg2, typename... T_Args>
   EmptyProperty(T_Arg1, T_Arg2, std::initializer_list<double> &&, T_Args... ) {}
   const EmptyProperty &value() { return *this; }
};
 
template <bool IsDebug=false>
struct ElasticDecayUtil {
   const xAOD::TruthParticle *getMother(const xAOD::TruthParticle &truth_particle, float max_energy_loss) const;
 
   // only used if IsDebug=true
   template <class T_OutStream>
   void dumpStatistics(T_OutStream &out) const;
 
   // @param binning number of bins, lower edge, upper edge in MeV
   void setEnergyLossBinning(const typename std::conditional<IsDebug, std::vector<float>, EmptyProperty>::type &binning);
 
   struct Empty {
      template <typename... T_Args>
      Empty(T_Args... ) {}
   };
   mutable typename std::conditional<IsDebug,std::mutex,Empty>::type m_mutex ATLAS_THREAD_SAFE;
 
   // PDG IDs of siblings.
   mutable typename std::conditional<IsDebug,std::set<int>, Empty>::type m_outgoingPdgIds ATLAS_THREAD_SAFE;

   mutable typename std::conditional<IsDebug,std::set<int>, Empty>::type m_outgoingMotherPdgIds ATLAS_THREAD_SAFE;
   enum ParticleTypes {
      kNoSibling,
      kElectron,
      kPhoton,
      kOther,
      kNParticleTypes
   };

   mutable typename std::conditional<IsDebug,std::array<ActsUtils::StatHist,kNParticleTypes>, Empty>::type m_energyLossStat ATLAS_THREAD_SAFE;
 
   // number of parents in a decay chain.
   mutable typename std::conditional<IsDebug,ActsUtils::StatHist,Empty>::type m_nParentsStat ATLAS_THREAD_SAFE {20,-.5,20.-.5};
};
 
#include "ElasticDecayUtil.icc"
#endif