Polarization.h

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/*
  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
*/
/* Author: Andrii Verbytskyi andrii.verbytskyi@mpp.mpg.de */
 
#ifndef ATLASHEPMC_POLARIZATION_H
#define ATLASHEPMC_POLARIZATION_H
#include "HepMC3/GenParticle.h"
#include "HepMC3/Attribute.h"
#include "AtlasHepMC/AttributeNames.h"
namespace HepMC {
class Polarization {
public:
    Polarization(const double a = 0.0, const double b = 0.0,
                  bool is_defined = false)
      : m_theta(a), m_phi(b), m_is_defined(is_defined) {};
    ~Polarization() {};
    double theta() const  { return m_theta;}
    double phi() const { return m_phi;}
    bool is_defined() const { return m_is_defined; }
    inline bool operator == (const Polarization &a) const { return (std::abs(a.phi() - phi()) <= 0.00001) && (std::abs(a.theta() - theta()) <= 0.00001);}
private:
    double m_theta;
    double m_phi;
    bool m_is_defined;
};
template <class T, std::enable_if_t<std::is_same<T, HepMC3::GenParticlePtr>::value || std::is_same<T, HepMC3::ConstGenParticlePtr>::value, bool > = true> 
inline Polarization polarization(const T& a) {
    std::shared_ptr<HepMC3::DoubleAttribute> phi_A = a->template attribute<HepMC3::DoubleAttribute>(HepMCStr::phi);
    std::shared_ptr<HepMC3::DoubleAttribute> theta_A = a->template attribute<HepMC3::DoubleAttribute>(HepMCStr::theta);
    const double phi = (phi_A ? phi_A->value() : 0.0);
    const double theta = (theta_A ? theta_A->value() : 0.0);
    const bool is_defined = phi_A && theta_A;
    return Polarization(theta, phi, is_defined);
}
template<class T> inline void  set_polarization(T& a, const Polarization& b) {
    a->add_attribute(HepMCStr::phi, std::make_shared<HepMC3::DoubleAttribute>(b.phi()));
    a->add_attribute(HepMCStr::theta, std::make_shared<HepMC3::DoubleAttribute>(b.theta()));
}
}
#endif