ConceptsBase.hpp

#pragma once

#include <type_traits>

#if defined(DOXYGEN)
  #define REQUIRES(...)
  #define CONCEPT constexpr
#else
  #define REQUIRES(...) std::enable_if_t<__VA_ARGS__ , int>* = nullptr
  #define CONCEPT constexpr
#endif

namespace AMDiS
{
  namespace Impl
  {
    // Workaround for MSVC (problems with alias templates in pack expansion)
    template <class... Args>
    struct VoidType { using type = void; };
  }

  template <class... Args>
  using Void_t = typename Impl::VoidType<Args...>::type;


  namespace Concepts
  {
    namespace _aux
    {
      template <class Concept, class = Void_t<>>
      struct models
          : std::false_type
      {};

      template <class Concept, class... Ts>
      struct models<Concept(Ts...), Void_t< decltype(std::declval<Concept>().requires_(std::declval<Ts>()...)) >>
          : std::true_type
      {};

      struct valid_expr
      {
        template <class... Ts>
        void operator()(Ts&&...) const;

#if defined(__GNUC__) && !defined(__clang__)
        template <class... Ts>
        void operator()(Ts const&...) const;
#endif
      };

    } // end namespace _aux

    template <class Concept>
    constexpr bool models = _aux::models<Concept>::value;

    constexpr _aux::valid_expr valid_expr = {};

  } // end namespace Concepts

} // end namespace AMDiS