mplVector.h

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#ifndef FWCore_Utilities_mplVector_h
#define FWCore_Utilities_mplVector_h
// -*- C++ -*-
//
// Package:     FWCore/Utilities
// Class  :     edm::mpl::Vector
//
//
// Original Author:  Chris Jones
//         Created:  Tues, 21 Jul 2020 14:29:51 GMT
//

// system include files
#include <type_traits>

// user include files

// forward declarations

namespace edm {
  namespace mpl {
    template <typename... T>
    class Vector {
    public:
      template <typename U>
      static constexpr bool contains() {
        return (std::is_same_v<U, T> || ...);
      }
    };

    template <typename T>
    struct Pop;

    template <typename F, typename... T>
    struct Pop<Vector<F, T...>> {
      constexpr static bool empty = false;
      using Item = F;
      using Remaining = Vector<T...>;
    };

    template <>
    struct Pop<Vector<>> {
      constexpr static bool empty = true;
      using Item = void;
      using Remaining = Vector<>;
    };

    template <typename T, typename U>
    struct Push;

    template <typename T, typename... U>
    struct Push<T, Vector<U...>> {
      constexpr static bool empty = false;
      using Result = Vector<T, U...>;
    };
  }  // namespace mpl
}  // namespace edm

#endif