PrimaryParticleInformation.h

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//

#ifndef G4BASE_PrimaryParticleInformation_h
#define G4BASE_PrimaryParticleInformation_h

// nusimdata
#include "nusimdata/SimulationBase/simb.h" // simb::GeneratedParticleIndex_t

// G4 Includes
#include "Geant4/G4VUserPrimaryParticleInformation.hh"
#include "Geant4/G4Allocator.hh"

// ART Includes
#include "canvas/Persistency/Common/Ptr.h"
#include "canvas/Persistency/Common/PtrVector.h"

// C++ standard library
#include <limits> // std::numeric_limits<>

// Forward declaration for this namespace.
namespace simb {
  class MCTruth;
  class MCParticle;
}

namespace g4b {
 
  class PrimaryParticleInformation : public G4VUserPrimaryParticleInformation {

  public:
    
    using GeneratedParticleIndex_t = simb::GeneratedParticleIndex_t;
    
    inline void* operator new(size_t);
    inline void operator delete(void*);
    
    // Accessors:
    const simb::MCTruth* GetMCTruth() const { return fMCTruth; }
    size_t const& MCTruthIndex()      const { return fMCTIndex; }
    
    GeneratedParticleIndex_t MCParticleIndex() const
      { return fMCParticleIndex; }
    
    simb::MCParticle const* GetMCParticle() const;
    
    bool IsInMCTruth()                const; // inline implementation below
    
    void SetMCTruth(const simb::MCTruth*     m,
                    size_t                   idx=0,
                    GeneratedParticleIndex_t indexInTruth = simb::NoGeneratedParticleIndex
                    );

    // Required by Geant4:
    virtual void Print() const override;

  private:

    // The MCTruth object associated with the G4PrimaryParticle.  If
    // this is zero, then there is no MCTruth object for this
    // particle (although in that case it's more likely that a
    // G4Base::PrimaryParticleInformation object would not have been
    // created in the first place.)
    // The MCTIndex is the index of the MCTruth object in the vector
    // of the ConvertMCTruthToG4 creating this object
    const simb::MCTruth* fMCTruth  = nullptr;
          size_t         fMCTIndex = 0;
    GeneratedParticleIndex_t fMCParticleIndex = simb::NoGeneratedParticleIndex;
  };

  // It's not likely, but there could be memory issues with these
  // PrimaryParticleInformation objects.  To make things work more smoothly
  // and quickly, use Geant4's memory allocation mechanism.
  
  extern G4Allocator<PrimaryParticleInformation> PrimaryParticleInformationAllocator;
  
  inline bool PrimaryParticleInformation::IsInMCTruth() const
    { return MCParticleIndex() != simb::NoGeneratedParticleIndex; }
  
  
  inline void PrimaryParticleInformation::SetMCTruth(
    const simb::MCTruth*     m,
    size_t                   idx /* = 0 */,
    GeneratedParticleIndex_t indexInTruth /* = simb::NoGeneratedParticleIndex */
    )
  { 
    fMCTruth = m;
    fMCTIndex = idx;
    fMCParticleIndex = indexInTruth;
  }
  
  inline void* PrimaryParticleInformation::operator new(size_t)
  {
    void *aPrimaryParticleInformation;
    aPrimaryParticleInformation = (void *) PrimaryParticleInformationAllocator.MallocSingle();
    return aPrimaryParticleInformation;
  }
  
  inline void PrimaryParticleInformation::operator delete(void *aPrimaryParticleInformation)
  {
    PrimaryParticleInformationAllocator.FreeSingle((PrimaryParticleInformation*) aPrimaryParticleInformation);
  }

}

#endif // G4BASE_PrimaryParticleInformation_h