1 //===----------------------------------------------------------------------===//
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
7 //===----------------------------------------------------------------------===//
9 #ifndef _LIBCPP___TYPE_TRAITS_IS_CALLABLE_H
10 #define _LIBCPP___TYPE_TRAITS_IS_CALLABLE_H
13 #include <__type_traits/integral_constant.h>
14 #include <__utility/declval.h>
16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
17 # pragma GCC system_header
20 _LIBCPP_BEGIN_NAMESPACE_STD
22 template <class _Func, class... _Args, class = decltype(std::declval<_Func>()(std::declval<_Args>()...))>
23 true_type __is_callable_helper(int);
25 false_type __is_callable_helper(...);
27 template <class _Func, class... _Args>
28 struct __is_callable : decltype(std::__is_callable_helper<_Func, _Args...>(0)) {};
30 _LIBCPP_END_NAMESPACE_STD
32 #endif // _LIBCPP___TYPE_TRAITS_IS_CALLABLE_H