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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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___TUPLE_FIND_INDEX_H10#define _LIBCPP___TUPLE_FIND_INDEX_H11 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_header18#endif19 20#if _LIBCPP_STD_VER >= 1421 22_LIBCPP_BEGIN_NAMESPACE_STD23 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 == _Nx36 ? __not_found37 : __find_detail::__find_idx_return(__i, __find_detail::__find_idx(__i + 1, __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_detail54 55template <typename _T1, typename... _Args>56struct __find_exactly_one_t : public __find_detail::__find_exactly_one_checked<_T1, _Args...> {};57 58_LIBCPP_END_NAMESPACE_STD59 60#endif // _LIBCPP_STD_VER >= 1461 62#endif // _LIBCPP___TUPLE_FIND_INDEX_H63