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___UTILITY_IN_PLACE_H 10 #define _LIBCPP___UTILITY_IN_PLACE_H 11 12 #include <__config> 13 #include <__type_traits/remove_cvref.h> 14 #include <cstddef> 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 #if _LIBCPP_STD_VER >= 17 23 24 struct _LIBCPP_EXPORTED_FROM_ABI in_place_t { 25 explicit in_place_t() = default; 26 }; 27 inline constexpr in_place_t in_place{}; 28 29 template <class _Tp> 30 struct _LIBCPP_TEMPLATE_VIS in_place_type_t { 31 _LIBCPP_HIDE_FROM_ABI explicit in_place_type_t() = default; 32 }; 33 template <class _Tp> 34 inline constexpr in_place_type_t<_Tp> in_place_type{}; 35 36 template <size_t _Idx> 37 struct _LIBCPP_TEMPLATE_VIS in_place_index_t { 38 _LIBCPP_HIDE_FROM_ABI explicit in_place_index_t() = default; 39 }; 40 template <size_t _Idx> 41 inline constexpr in_place_index_t<_Idx> in_place_index{}; 42 43 template <class _Tp> 44 struct __is_inplace_type_imp : false_type {}; 45 template <class _Tp> 46 struct __is_inplace_type_imp<in_place_type_t<_Tp>> : true_type {}; 47 48 template <class _Tp> 49 using __is_inplace_type = __is_inplace_type_imp<__remove_cvref_t<_Tp>>; 50 51 template <class _Tp> 52 struct __is_inplace_index_imp : false_type {}; 53 template <size_t _Idx> 54 struct __is_inplace_index_imp<in_place_index_t<_Idx>> : true_type {}; 55 56 template <class _Tp> 57 using __is_inplace_index = __is_inplace_index_imp<__remove_cvref_t<_Tp>>; 58 59 #endif // _LIBCPP_STD_VER >= 17 60 61 _LIBCPP_END_NAMESPACE_STD 62 63 #endif // _LIBCPP___UTILITY_IN_PLACE_H 64