detail_callable.hpp

#pragma once
 
#include <utility>
 
#include "../global.hpp"
namespace Cvb
{
  CVB_BEGIN_INLINE_NS

  namespace Internal
  {
    template <typename>
    struct true_given : std::true_type
    {
    };
 
    namespace  // NOLINT(cert-dcl59-cpp)
    {
      struct is_callable_tester
      {
        template <typename Fun, typename... Args>
        true_given<decltype(std::declval<Fun>()(std::declval<Args>()...))> static test(int);
        template <typename...>
        std::false_type static test(...);
      };
    }  // namespace
 
    template <typename T>
    struct is_callable;
 
    template <typename Fun, typename... Args>
    struct is_callable<Fun(Args...)> : decltype(is_callable_tester::test<Fun, Args...>(0))
    {
    };
 
    template <typename Lambda, std::size_t M, typename Testarg, typename... Testargs>
    struct IsCallableMParameters : IsCallableMParameters<Lambda, M - 1, Testarg, Testarg, Testargs...>
    {
    };
 
    template <typename Lambda, typename Testarg, typename... Testargs>
    struct IsCallableMParameters<Lambda, 0, Testarg, Testargs...> : is_callable<Lambda(Testargs...)>
    {
    };
  }  // namespace Internal
  CVB_END_INLINE_NS
}  // namespace Cvb