PhysicsAnalysis/D3PDMaker/D3PDMakerUtils/D3PDMakerUtils/Types.h

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// This file's extension implies that it's C, but it's really -*- C++ -*-.
/*
  Copyright (C) 2002-2023 CERN for the benefit of the ATLAS collaboration
*/
#ifndef D3PDMAKERUTILS_TYPES_H
#define D3PDMAKERUTILS_TYPES_H
 
 
#include <typeinfo>
#include <cstdlib>
#include <tuple>
 
 
namespace D3PD {
 
 
class NoType {};
 
 
template <class T>
struct WrapType
{
  using type = T;
};
 
 
template <class... TYPES>
using Types = std::tuple<WrapType<TYPES>...>;
 
 
template <class T, int N>
struct SelectType
{
  typedef T type;
};
 
 
template <int N, class... TYPES>
struct SelectType<Types<TYPES...>, N>
{
  using type = typename std::tuple_element_t<N, Types<TYPES...> >::type;
};
 
 
template <class T0>
const std::type_info& multiTypeInfo (Types<T0>*, size_t which)
{
  if (which == 0) return typeid (T0);
  std::abort();
}
 
 
template <class T0, class... TYPES>
const std::type_info& multiTypeInfo (Types<T0, TYPES...>*, size_t which)
{
  if (which == 0) return typeid (T0);
  return multiTypeInfo (static_cast<Types<TYPES...>*>(nullptr), which-1);
}
 
 
template <class T>
const std::type_info& multiTypeInfo (T*, size_t /*which*/)
{
  return typeid (T);
}
 
 
template <class T>
struct ButFirstType
{
  using type = T;
};
 
 
template <class T0, class... TYPES>
struct ButFirstType<Types<T0, TYPES...> >
{
  using type = Types<TYPES...>;
};
 
 
template <class T>
using ButFirstType_t = typename ButFirstType<T>::type;
 
 
} // namespace D3PD
 
 
 
#endif // not D3PDMAKERUTILS_TYPES_H