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___TUPLE_FIND_INDEX_H
10#define _LIBCPP___TUPLE_FIND_INDEX_H
11
12#include <__config>
13#include <__cstddef/size_t.h>
14#include <__type_traits/is_same.h>
15
16#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
17# pragma GCC system_header
18#endif
19
20#if _LIBCPP_STD_VER >= 14
21
22_LIBCPP_BEGIN_NAMESPACE_STD
23
24namespace __find_detail {
25
26static constexpr size_t __not_found = static_cast<size_t>(-1);
27static constexpr size_t __ambiguous = __not_found - 1;
28
29inline _LIBCPP_HIDE_FROM_ABI constexpr size_t __find_idx_return(size_t __curr_i, size_t __res, bool __matches) {
30 return !__matches ? __res : (__res == __not_found ? __curr_i : __ambiguous);
31}
32
33template <size_t _Nx>
34inline _LIBCPP_HIDE_FROM_ABI constexpr size_t __find_idx(size_t __i, const bool (&__matches)[_Nx]) {
35 return __i == _Nx
36 ? __not_found
37 : __find_detail::__find_idx_return(curr_i: __i, res: __find_detail::__find_idx(__i + 1, __matches), matches: __matches[__i]);
38}
39
40template <class _T1, class... _Args>
41struct __find_exactly_one_checked {
42 static constexpr bool __matches[sizeof...(_Args)] = {is_same<_T1, _Args>::value...};
43 static constexpr size_t value = __find_detail::__find_idx(0, __matches);
44 static_assert(value != __not_found, "type not found in type list");
45 static_assert(value != __ambiguous, "type occurs more than once in type list");
46};
47
48template <class _T1>
49struct __find_exactly_one_checked<_T1> {
50 static_assert(!is_same<_T1, _T1>::value, "type not in empty type list");
51};
52
53} // namespace __find_detail
54
55template <typename _T1, typename... _Args>
56struct __find_exactly_one_t : public __find_detail::__find_exactly_one_checked<_T1, _Args...> {};
57
58_LIBCPP_END_NAMESPACE_STD
59
60#endif // _LIBCPP_STD_VER >= 14
61
62#endif // _LIBCPP___TUPLE_FIND_INDEX_H
63