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1// -*- C++ -*-2//===----------------------------------------------------------------------===//3//4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.5// See https://llvm.org/LICENSE.txt for license information.6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception7//8//===----------------------------------------------------------------------===//9#ifndef _LIBCPP___EXPECTED_UNEXPECTED_H10#define _LIBCPP___EXPECTED_UNEXPECTED_H11 12#include <__config>13#include <__type_traits/conjunction.h>14#include <__type_traits/is_array.h>15#include <__type_traits/is_const.h>16#include <__type_traits/is_constructible.h>17#include <__type_traits/is_nothrow_constructible.h>18#include <__type_traits/is_object.h>19#include <__type_traits/is_same.h>20#include <__type_traits/is_swappable.h>21#include <__type_traits/is_volatile.h>22#include <__type_traits/negation.h>23#include <__type_traits/remove_cvref.h>24#include <__utility/forward.h>25#include <__utility/in_place.h>26#include <__utility/move.h>27#include <__utility/swap.h>28#include <initializer_list>29 30#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)31# pragma GCC system_header32#endif33 34_LIBCPP_PUSH_MACROS35#include <__undef_macros>36 37#if _LIBCPP_STD_VER >= 2338 39_LIBCPP_BEGIN_NAMESPACE_STD40 41template <class _Err>42class unexpected;43 44template <class _Tp>45struct __is_std_unexpected : false_type {};46 47template <class _Err>48struct __is_std_unexpected<unexpected<_Err>> : true_type {};49 50template <class _Tp>51using __valid_std_unexpected _LIBCPP_NODEBUG = _BoolConstant< //52 is_object_v<_Tp> && //53 !is_array_v<_Tp> && //54 !__is_std_unexpected<_Tp>::value && //55 !is_const_v<_Tp> && //56 !is_volatile_v<_Tp> //57 >;58 59template <class _Err>60class unexpected {61 static_assert(__valid_std_unexpected<_Err>::value,62 "[expected.un.general] states a program that instantiates std::unexpected for a non-object type, an "63 "array type, a specialization of unexpected, or a cv-qualified type is ill-formed.");64 65public:66 _LIBCPP_HIDE_FROM_ABI constexpr unexpected(const unexpected&) = default;67 _LIBCPP_HIDE_FROM_ABI constexpr unexpected(unexpected&&) = default;68 69 template <class _Error = _Err>70 requires(!is_same_v<remove_cvref_t<_Error>, unexpected> && //71 !is_same_v<remove_cvref_t<_Error>, in_place_t> && //72 is_constructible_v<_Err, _Error>)73 _LIBCPP_HIDE_FROM_ABI constexpr explicit unexpected(_Error&& __error) //74 noexcept(is_nothrow_constructible_v<_Err, _Error>) // strengthened75 : __unex_(std::forward<_Error>(__error)) {}76 77 template <class... _Args>78 requires is_constructible_v<_Err, _Args...>79 _LIBCPP_HIDE_FROM_ABI constexpr explicit unexpected(in_place_t, _Args&&... __args) //80 noexcept(is_nothrow_constructible_v<_Err, _Args...>) // strengthened81 : __unex_(std::forward<_Args>(__args)...) {}82 83 template <class _Up, class... _Args>84 requires is_constructible_v<_Err, initializer_list<_Up>&, _Args...>85 _LIBCPP_HIDE_FROM_ABI constexpr explicit unexpected(in_place_t, initializer_list<_Up> __il, _Args&&... __args) //86 noexcept(is_nothrow_constructible_v<_Err, initializer_list<_Up>&, _Args...>) // strengthened87 : __unex_(__il, std::forward<_Args>(__args)...) {}88 89 _LIBCPP_HIDE_FROM_ABI constexpr unexpected& operator=(const unexpected&) = default;90 _LIBCPP_HIDE_FROM_ABI constexpr unexpected& operator=(unexpected&&) = default;91 92 _LIBCPP_HIDE_FROM_ABI constexpr const _Err& error() const& noexcept { return __unex_; }93 _LIBCPP_HIDE_FROM_ABI constexpr _Err& error() & noexcept { return __unex_; }94 _LIBCPP_HIDE_FROM_ABI constexpr const _Err&& error() const&& noexcept { return std::move(__unex_); }95 _LIBCPP_HIDE_FROM_ABI constexpr _Err&& error() && noexcept { return std::move(__unex_); }96 97 _LIBCPP_HIDE_FROM_ABI constexpr void swap(unexpected& __other) noexcept(is_nothrow_swappable_v<_Err>) {98 static_assert(is_swappable_v<_Err>, "unexpected::swap requires is_swappable_v<E> to be true");99 using std::swap;100 swap(__unex_, __other.__unex_);101 }102 103 _LIBCPP_HIDE_FROM_ABI friend constexpr void swap(unexpected& __x, unexpected& __y) noexcept(noexcept(__x.swap(__y)))104 requires is_swappable_v<_Err>105 {106 __x.swap(__y);107 }108 109 template <class _Err2>110 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const unexpected& __x, const unexpected<_Err2>& __y) {111 return __x.__unex_ == __y.error();112 }113 114private:115 _Err __unex_;116};117 118template <class _Err>119unexpected(_Err) -> unexpected<_Err>;120 121_LIBCPP_END_NAMESPACE_STD122 123#endif // _LIBCPP_STD_VER >= 23124 125_LIBCPP_POP_MACROS126 127#endif // _LIBCPP___EXPECTED_UNEXPECTED_H128