Program Listing for File sfinae.hpp

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/*
Copyright (c) 2016-18, Lawrence Livermore National Security, LLC.
Produced at the Lawrence Livermore National Laboratory
Maintained by Tom Scogland <scogland1@llnl.gov>
CODE-756261, All rights reserved.
This file is part of camp.
For details about use and distribution, please read LICENSE and NOTICE from
http://github.com/llnl/camp
*/

#ifndef CAMP_DETAIL_SFINAE_HPP
#define CAMP_DETAIL_SFINAE_HPP

#include "camp/helpers.hpp"
#include "camp/number/number.hpp"
#include "camp/value.hpp"

#include <type_traits>

namespace camp
{

namespace detail
{

  // caller pattern from metal library
  template <template <typename...> class expr, typename... vals>
  struct caller;

  template <
      template <typename...> class expr,
      typename... vals,
      typename std::enable_if<is_value<expr<vals...>>::value>::type* = nullptr>
  value<expr<vals...>> sfinae(caller<expr, vals...>*);

  value<> sfinae(...);

  template <template <typename...> class expr, typename... vals>
  struct caller : decltype(sfinae(declptr<caller<expr, vals...>>())) {
  };

  template <template <typename...> class Expr, typename... Vals>
  struct call_s : caller<Expr, Vals...> {
  };

  template <template <typename...> class Expr, typename... Vals>
  using call = Expr<Vals...>;
};  // namespace detail

}  // end namespace camp

#endif /* CAMP_DETAIL_SFINAE_HPP */