ParticleID.hpp

#ifndef PARTICLE_ID_HPP
#define PARTICLE_ID_HPP

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /* HAVE_CONFIG_H */

#include <ostream>
#if defined(HAVE_TR1_FUNCTIONAL)
#include <tr1/functional>
#elif defined(HAVE_STD_HASH)
#include <functional>
#elif defined(HAVE_BOOST_FUNCTIONAL_HASH_HPP)
#include <boost/functional/hash.hpp>
#endif
#include "Identifier.hpp"

struct ParticleID: public Identifier<ParticleID, unsigned long long, int>
// The ParticleID is a class for the identification of particles
{
    typedef Identifier<ParticleID, unsigned long long, int> base_type;

    ParticleID(value_type const& value = value_type(0, 0))
        : base_type(value) {}
};

#if defined(HAVE_TR1_FUNCTIONAL)
namespace std { namespace tr1 {
#elif defined(HAVE_STD_HASH)
namespace std {
#elif defined(HAVE_BOOST_FUNCTIONAL_HASH_HPP)
namespace boost {
#endif

template<>
struct hash<ParticleID>
// Hashing function??
{
    std::size_t operator()(ParticleID const& val) const
    {
        return static_cast<std::size_t>(val().first ^ val().second);
    }
};

#if defined(HAVE_TR1_FUNCTIONAL)
} } // namespace std::tr1
#elif defined(HAVE_STD_HASH)
} // namespace std
#elif defined(HAVE_BOOST_FUNCTIONAL_HASH_HPP)
} // namespace boost
#endif

template<typename Tstrm_, typename Ttraits_>
inline std::basic_ostream<Tstrm_, Ttraits_>& operator<<(std::basic_ostream<Tstrm_, Ttraits_>& strm,
        const ParticleID& v)
// Provides a stream of characters (a string) of the 'particle id' that allows for printing.
{
    strm << "PID(" << v().first << ":" << v().second << ")";
    return strm;
}

#endif /* PARTICLE_ID_HPP */