1*0fca6ea1SDimitry Andric //===----------------------------------------------------------------------===// 2*0fca6ea1SDimitry Andric // 3*0fca6ea1SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4*0fca6ea1SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 5*0fca6ea1SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6*0fca6ea1SDimitry Andric // 7*0fca6ea1SDimitry Andric //===----------------------------------------------------------------------===// 8*0fca6ea1SDimitry Andric 9*0fca6ea1SDimitry Andric #ifndef _LIBCPP___TUPLE_FIND_INDEX_H 10*0fca6ea1SDimitry Andric #define _LIBCPP___TUPLE_FIND_INDEX_H 11*0fca6ea1SDimitry Andric 12*0fca6ea1SDimitry Andric #include <__config> 13*0fca6ea1SDimitry Andric #include <__type_traits/is_same.h> 14*0fca6ea1SDimitry Andric #include <cstddef> 15*0fca6ea1SDimitry Andric 16*0fca6ea1SDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 17*0fca6ea1SDimitry Andric # pragma GCC system_header 18*0fca6ea1SDimitry Andric #endif 19*0fca6ea1SDimitry Andric 20*0fca6ea1SDimitry Andric #if _LIBCPP_STD_VER >= 14 21*0fca6ea1SDimitry Andric 22*0fca6ea1SDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 23*0fca6ea1SDimitry Andric 24*0fca6ea1SDimitry Andric namespace __find_detail { 25*0fca6ea1SDimitry Andric 26*0fca6ea1SDimitry Andric static constexpr size_t __not_found = static_cast<size_t>(-1); 27*0fca6ea1SDimitry Andric static constexpr size_t __ambiguous = __not_found - 1; 28*0fca6ea1SDimitry Andric 29*0fca6ea1SDimitry Andric inline _LIBCPP_HIDE_FROM_ABI constexpr size_t __find_idx_return(size_t __curr_i, size_t __res, bool __matches) { 30*0fca6ea1SDimitry Andric return !__matches ? __res : (__res == __not_found ? __curr_i : __ambiguous); 31*0fca6ea1SDimitry Andric } 32*0fca6ea1SDimitry Andric 33*0fca6ea1SDimitry Andric template <size_t _Nx> 34*0fca6ea1SDimitry Andric inline _LIBCPP_HIDE_FROM_ABI constexpr size_t __find_idx(size_t __i, const bool (&__matches)[_Nx]) { 35*0fca6ea1SDimitry Andric return __i == _Nx 36*0fca6ea1SDimitry Andric ? __not_found 37*0fca6ea1SDimitry Andric : __find_detail::__find_idx_return(__i, __find_detail::__find_idx(__i + 1, __matches), __matches[__i]); 38*0fca6ea1SDimitry Andric } 39*0fca6ea1SDimitry Andric 40*0fca6ea1SDimitry Andric template <class _T1, class... _Args> 41*0fca6ea1SDimitry Andric struct __find_exactly_one_checked { 42*0fca6ea1SDimitry Andric static constexpr bool __matches[sizeof...(_Args)] = {is_same<_T1, _Args>::value...}; 43*0fca6ea1SDimitry Andric static constexpr size_t value = __find_detail::__find_idx(0, __matches); 44*0fca6ea1SDimitry Andric static_assert(value != __not_found, "type not found in type list"); 45*0fca6ea1SDimitry Andric static_assert(value != __ambiguous, "type occurs more than once in type list"); 46*0fca6ea1SDimitry Andric }; 47*0fca6ea1SDimitry Andric 48*0fca6ea1SDimitry Andric template <class _T1> 49*0fca6ea1SDimitry Andric struct __find_exactly_one_checked<_T1> { 50*0fca6ea1SDimitry Andric static_assert(!is_same<_T1, _T1>::value, "type not in empty type list"); 51*0fca6ea1SDimitry Andric }; 52*0fca6ea1SDimitry Andric 53*0fca6ea1SDimitry Andric } // namespace __find_detail 54*0fca6ea1SDimitry Andric 55*0fca6ea1SDimitry Andric template <typename _T1, typename... _Args> 56*0fca6ea1SDimitry Andric struct __find_exactly_one_t : public __find_detail::__find_exactly_one_checked<_T1, _Args...> {}; 57*0fca6ea1SDimitry Andric 58*0fca6ea1SDimitry Andric _LIBCPP_END_NAMESPACE_STD 59*0fca6ea1SDimitry Andric 60*0fca6ea1SDimitry Andric #endif // _LIBCPP_STD_VER >= 14 61*0fca6ea1SDimitry Andric 62*0fca6ea1SDimitry Andric #endif // _LIBCPP___TUPLE_FIND_INDEX_H 63