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> 14 15 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 16 # pragma GCC system_header 17 #endif 18 19 _LIBCPP_BEGIN_NAMESPACE_STD 20 21 #if _LIBCPP_STD_VER > 14 22 23 struct _LIBCPP_TYPE_VIS in_place_t { 24 explicit in_place_t() = default; 25 }; 26 inline constexpr in_place_t in_place{}; 27 28 template <class _Tp> 29 struct _LIBCPP_TEMPLATE_VIS in_place_type_t { 30 explicit in_place_type_t() = default; 31 }; 32 template <class _Tp> 33 inline constexpr in_place_type_t<_Tp> in_place_type{}; 34 35 template <size_t _Idx> 36 struct _LIBCPP_TEMPLATE_VIS in_place_index_t { 37 explicit in_place_index_t() = default; 38 }; 39 template <size_t _Idx> 40 inline constexpr in_place_index_t<_Idx> in_place_index{}; 41 42 template <class _Tp> struct __is_inplace_type_imp : false_type {}; 43 template <class _Tp> struct __is_inplace_type_imp<in_place_type_t<_Tp>> : true_type {}; 44 45 template <class _Tp> 46 using __is_inplace_type = __is_inplace_type_imp<__uncvref_t<_Tp>>; 47 48 template <class _Tp> struct __is_inplace_index_imp : false_type {}; 49 template <size_t _Idx> struct __is_inplace_index_imp<in_place_index_t<_Idx>> : true_type {}; 50 51 template <class _Tp> 52 using __is_inplace_index = __is_inplace_index_imp<__uncvref_t<_Tp>>; 53 54 #endif // _LIBCPP_STD_VER > 14 55 56 _LIBCPP_END_NAMESPACE_STD 57 58 #endif // _LIBCPP___UTILITY_IN_PLACE_H 59