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___OPTIONAL_MAKE_OPTIONAL_H
10#define _LIBCPP___OPTIONAL_MAKE_OPTIONAL_H
11
12#include <__config>
13#include <__fwd/optional.h>
14#include <__type_traits/decay.h>
15#include <__type_traits/enable_if.h>
16#include <__type_traits/integral_constant.h>
17#include <__type_traits/is_constructible.h>
18#include <__type_traits/reference_constructs_from_temporary.h>
19#include <__utility/forward.h>
20#include <__utility/in_place.h>
21
22#include <initializer_list>
23
24#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
25# pragma GCC system_header
26#endif
27
28_LIBCPP_PUSH_MACROS
29#include <__undef_macros>
30
31#if _LIBCPP_STD_VER >= 17
32
33_LIBCPP_BEGIN_NAMESPACE_STD
34
35struct __make_optional_barrier_tag {
36 explicit __make_optional_barrier_tag() = default;
37};
38
39template <class _Tp, class... _Args>
40inline constexpr bool __is_constructible_for_optional_v = is_constructible_v<_Tp, _Args...>;
41
42template <class _Tp, class... _Args>
43struct __is_constructible_for_optional : bool_constant<__is_constructible_for_optional_v<_Tp, _Args...>> {};
44
45template <class _Tp, class _Up, class... _Args>
46inline constexpr bool __is_constructible_for_optional_initializer_list_v =
47 is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>;
48
49# if _LIBCPP_STD_VER >= 26
50template <class _Tp, class... _Args>
51inline constexpr bool __is_constructible_for_optional_v<_Tp&, _Args...> = false;
52
53template <class _Tp, class _Arg>
54inline constexpr bool __is_constructible_for_optional_v<_Tp&, _Arg> =
55 is_constructible_v<_Tp&, _Arg> && !reference_constructs_from_temporary_v<_Tp&, _Arg>;
56
57template <class _Tp, class _Up, class... _Args>
58inline constexpr bool __is_constructible_for_optional_initializer_list_v<_Tp&, _Up, _Args...> = false;
59# endif
60
61template <
62# if _LIBCPP_STD_VER >= 26
63 __make_optional_barrier_tag = __make_optional_barrier_tag{},
64# endif
65 class _Tp,
66 enable_if_t<is_constructible_v<decay_t<_Tp>, _Tp>, int> = 0>
67[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr optional<decay_t<_Tp>> make_optional(_Tp&& __v) {
68 return optional<decay_t<_Tp>>(std::forward<_Tp>(__v));
69}
70
71template <class _Tp, class... _Args, enable_if_t<__is_constructible_for_optional_v<_Tp, _Args...>, int> = 0>
72[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr optional<_Tp> make_optional(_Args&&... __args) {
73 return optional<_Tp>(in_place, std::forward<_Args>(__args)...);
74}
75
76template <class _Tp,
77 class _Up,
78 class... _Args,
79 enable_if_t<__is_constructible_for_optional_initializer_list_v<_Tp, _Up, _Args...>, int> = 0>
80[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr optional<_Tp>
81make_optional(initializer_list<_Up> __il, _Args&&... __args) {
82 return optional<_Tp>(in_place, __il, std::forward<_Args>(__args)...);
83}
84
85_LIBCPP_END_NAMESPACE_STD
86
87#endif // _LIBCPP_STD_VER >= 17
88
89_LIBCPP_POP_MACROS
90
91#endif // _LIBCPP___OPTIONAL_MAKE_OPTIONAL_H
92