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 > 14
23 
24 struct _LIBCPP_TYPE_VIS 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     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     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> struct __is_inplace_type_imp : false_type {};
44 template <class _Tp> struct __is_inplace_type_imp<in_place_type_t<_Tp>> : true_type {};
45 
46 template <class _Tp>
47 using __is_inplace_type = __is_inplace_type_imp<__remove_cvref_t<_Tp>>;
48 
49 template <class _Tp> struct __is_inplace_index_imp : false_type {};
50 template <size_t _Idx> struct __is_inplace_index_imp<in_place_index_t<_Idx>> : true_type {};
51 
52 template <class _Tp>
53 using __is_inplace_index = __is_inplace_index_imp<__remove_cvref_t<_Tp>>;
54 
55 #endif // _LIBCPP_STD_VER > 14
56 
57 _LIBCPP_END_NAMESPACE_STD
58 
59 #endif // _LIBCPP___UTILITY_IN_PLACE_H
60