1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___TYPE_TRAITS_IS_CALLABLE_H
10#define _LIBCPP___TYPE_TRAITS_IS_CALLABLE_H
11
12#include <__config>
13#include <__type_traits/integral_constant.h>
14#include <__utility/declval.h>
15
16#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
17#  pragma GCC system_header
18#endif
19
20_LIBCPP_BEGIN_NAMESPACE_STD
21
22template <class _Func, class... _Args, class = decltype(std::declval<_Func>()(std::declval<_Args>()...))>
23true_type __is_callable_helper(int);
24template <class...>
25false_type __is_callable_helper(...);
26
27template <class _Func, class... _Args>
28struct __is_callable : decltype(std::__is_callable_helper<_Func, _Args...>(0)) {};
29
30_LIBCPP_END_NAMESPACE_STD
31
32#endif // _LIBCPP___TYPE_TRAITS_IS_CALLABLE_H
33