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_DISJUNCTION_H
10 #define _LIBCPP___TYPE_TRAITS_DISJUNCTION_H
11 
12 #include <__config>
13 #include <__type_traits/conditional.h>
14 #include <__type_traits/integral_constant.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 
22 template <bool>
23 struct _OrImpl;
24 
25 template <>
26 struct _OrImpl<true> {
27   template <class _Res, class _First, class... _Rest>
28   using _Result _LIBCPP_NODEBUG =
29       typename _OrImpl<!bool(_First::value) && sizeof...(_Rest) != 0>::template _Result<_First, _Rest...>;
30 };
31 
32 template <>
33 struct _OrImpl<false> {
34   template <class _Res, class...>
35   using _Result = _Res;
36 };
37 
38 template <class... _Args>
39 using _Or _LIBCPP_NODEBUG = typename _OrImpl<sizeof...(_Args) != 0>::template _Result<false_type, _Args...>;
40 
41 #if _LIBCPP_STD_VER > 14
42 
43 template <class... _Args>
44 struct disjunction : _Or<_Args...> {};
45 
46 template <class... _Args>
47 inline constexpr bool disjunction_v = _Or<_Args...>::value;
48 
49 #endif // _LIBCPP_STD_VER > 14
50 
51 _LIBCPP_END_NAMESPACE_STD
52 
53 #endif // _LIBCPP___TYPE_TRAITS_DISJUNCTION_H
54