1 | // <variant> -*- C++ -*-
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2 |
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3 | // Copyright (C) 2016-2021 Free Software Foundation, Inc.
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4 | //
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5 | // This file is part of the GNU ISO C++ Library. This library is free
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6 | // software; you can redistribute it and/or modify it under the
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7 | // terms of the GNU General Public License as published by the
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8 | // Free Software Foundation; either version 3, or (at your option)
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9 | // any later version.
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10 |
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11 | // This library is distributed in the hope that it will be useful,
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12 | // but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 | // GNU General Public License for more details.
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15 |
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16 | // Under Section 7 of GPL version 3, you are granted additional
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17 | // permissions described in the GCC Runtime Library Exception, version
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18 | // 3.1, as published by the Free Software Foundation.
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19 |
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20 | // You should have received a copy of the GNU General Public License and
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21 | // a copy of the GCC Runtime Library Exception along with this program;
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22 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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23 | // <http://www.gnu.org/licenses/>.
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24 |
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25 | /** @file variant
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26 | * This is the `<variant>` C++ Library header.
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27 | */
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28 |
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29 | #ifndef _GLIBCXX_VARIANT
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30 | #define _GLIBCXX_VARIANT 1
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31 |
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32 | #pragma GCC system_header
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33 |
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34 | #if __cplusplus >= 201703L
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35 |
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36 | #include <type_traits>
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37 | #include <utility>
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38 | #include <bits/enable_special_members.h>
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39 | #include <bits/functexcept.h>
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40 | #include <bits/move.h>
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41 | #include <bits/functional_hash.h>
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42 | #include <bits/invoke.h>
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43 | #include <ext/aligned_buffer.h>
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44 | #include <bits/parse_numbers.h>
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45 | #include <bits/stl_iterator_base_types.h>
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46 | #include <bits/stl_iterator_base_funcs.h>
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47 | #include <bits/stl_construct.h>
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48 | #if __cplusplus > 201703L
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49 | # include <compare>
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50 | #endif
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51 |
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52 | namespace std _GLIBCXX_VISIBILITY(default)
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53 | {
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54 | _GLIBCXX_BEGIN_NAMESPACE_VERSION
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55 |
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56 | namespace __detail
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57 | {
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58 | namespace __variant
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59 | {
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60 | template<size_t _Np, typename... _Types>
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61 | struct _Nth_type;
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62 |
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63 | template<size_t _Np, typename _First, typename... _Rest>
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64 | struct _Nth_type<_Np, _First, _Rest...>
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65 | : _Nth_type<_Np-1, _Rest...> { };
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66 |
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67 | template<typename _First, typename... _Rest>
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68 | struct _Nth_type<0, _First, _Rest...>
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69 | { using type = _First; };
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70 |
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71 | } // namespace __variant
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72 | } // namespace __detail
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73 |
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74 | #define __cpp_lib_variant 201606L
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75 |
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76 | template<typename... _Types> class tuple;
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77 | template<typename... _Types> class variant;
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78 | template <typename> struct hash;
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79 |
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80 | template<typename _Variant>
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81 | struct variant_size;
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82 |
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83 | template<typename _Variant>
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84 | struct variant_size<const _Variant> : variant_size<_Variant> {};
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85 |
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86 | template<typename _Variant>
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87 | struct variant_size<volatile _Variant> : variant_size<_Variant> {};
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88 |
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89 | template<typename _Variant>
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90 | struct variant_size<const volatile _Variant> : variant_size<_Variant> {};
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91 |
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92 | template<typename... _Types>
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93 | struct variant_size<variant<_Types...>>
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94 | : std::integral_constant<size_t, sizeof...(_Types)> {};
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95 |
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96 | template<typename _Variant>
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97 | inline constexpr size_t variant_size_v = variant_size<_Variant>::value;
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98 |
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99 | template<size_t _Np, typename _Variant>
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100 | struct variant_alternative;
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101 |
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102 | template<size_t _Np, typename _First, typename... _Rest>
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103 | struct variant_alternative<_Np, variant<_First, _Rest...>>
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104 | : variant_alternative<_Np-1, variant<_Rest...>> {};
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105 |
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106 | template<typename _First, typename... _Rest>
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107 | struct variant_alternative<0, variant<_First, _Rest...>>
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108 | { using type = _First; };
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109 |
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110 | template<size_t _Np, typename _Variant>
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111 | using variant_alternative_t =
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112 | typename variant_alternative<_Np, _Variant>::type;
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113 |
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114 | template<size_t _Np, typename _Variant>
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115 | struct variant_alternative<_Np, const _Variant>
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116 | { using type = add_const_t<variant_alternative_t<_Np, _Variant>>; };
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117 |
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118 | template<size_t _Np, typename _Variant>
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119 | struct variant_alternative<_Np, volatile _Variant>
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120 | { using type = add_volatile_t<variant_alternative_t<_Np, _Variant>>; };
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121 |
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122 | template<size_t _Np, typename _Variant>
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123 | struct variant_alternative<_Np, const volatile _Variant>
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124 | { using type = add_cv_t<variant_alternative_t<_Np, _Variant>>; };
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125 |
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126 | inline constexpr size_t variant_npos = -1;
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127 |
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128 | template<size_t _Np, typename... _Types>
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129 | constexpr variant_alternative_t<_Np, variant<_Types...>>&
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130 | get(variant<_Types...>&);
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131 |
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132 | template<size_t _Np, typename... _Types>
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133 | constexpr variant_alternative_t<_Np, variant<_Types...>>&&
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134 | get(variant<_Types...>&&);
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135 |
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136 | template<size_t _Np, typename... _Types>
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137 | constexpr variant_alternative_t<_Np, variant<_Types...>> const&
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138 | get(const variant<_Types...>&);
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139 |
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140 | template<size_t _Np, typename... _Types>
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141 | constexpr variant_alternative_t<_Np, variant<_Types...>> const&&
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142 | get(const variant<_Types...>&&);
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143 |
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144 | template<typename _Result_type, typename _Visitor, typename... _Variants>
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145 | constexpr decltype(auto)
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146 | __do_visit(_Visitor&& __visitor, _Variants&&... __variants);
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147 |
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148 | template <typename... _Types, typename _Tp>
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149 | decltype(auto)
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150 | __variant_cast(_Tp&& __rhs)
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151 | {
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152 | if constexpr (is_lvalue_reference_v<_Tp>)
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153 | {
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154 | if constexpr (is_const_v<remove_reference_t<_Tp>>)
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155 | return static_cast<const variant<_Types...>&>(__rhs);
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156 | else
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157 | return static_cast<variant<_Types...>&>(__rhs);
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158 | }
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159 | else
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160 | return static_cast<variant<_Types...>&&>(__rhs);
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161 | }
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162 |
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163 | namespace __detail
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164 | {
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165 | namespace __variant
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166 | {
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167 | // Returns the first appearance of _Tp in _Types.
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168 | // Returns sizeof...(_Types) if _Tp is not in _Types.
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169 | template<typename _Tp, typename... _Types>
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170 | struct __index_of : std::integral_constant<size_t, 0> {};
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171 |
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172 | template<typename _Tp, typename... _Types>
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173 | inline constexpr size_t __index_of_v = __index_of<_Tp, _Types...>::value;
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174 |
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175 | template<typename _Tp, typename _First, typename... _Rest>
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176 | struct __index_of<_Tp, _First, _Rest...> :
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177 | std::integral_constant<size_t, is_same_v<_Tp, _First>
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178 | ? 0 : __index_of_v<_Tp, _Rest...> + 1> {};
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179 |
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180 | // used for raw visitation
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181 | struct __variant_cookie {};
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182 | // used for raw visitation with indices passed in
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183 | struct __variant_idx_cookie { using type = __variant_idx_cookie; };
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184 | // Used to enable deduction (and same-type checking) for std::visit:
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185 | template<typename _Tp> struct __deduce_visit_result { using type = _Tp; };
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186 |
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187 | // Visit variants that might be valueless.
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188 | template<typename _Visitor, typename... _Variants>
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189 | constexpr void
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190 | __raw_visit(_Visitor&& __visitor, _Variants&&... __variants)
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191 | {
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192 | std::__do_visit<__variant_cookie>(std::forward<_Visitor>(__visitor),
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193 | std::forward<_Variants>(__variants)...);
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194 | }
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195 |
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196 | // Visit variants that might be valueless, passing indices to the visitor.
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197 | template<typename _Visitor, typename... _Variants>
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198 | constexpr void
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199 | __raw_idx_visit(_Visitor&& __visitor, _Variants&&... __variants)
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200 | {
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201 | std::__do_visit<__variant_idx_cookie>(std::forward<_Visitor>(__visitor),
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202 | std::forward<_Variants>(__variants)...);
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203 | }
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204 |
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205 | // _Uninitialized<T> is guaranteed to be a trivially destructible type,
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206 | // even if T is not.
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207 | template<typename _Type, bool = std::is_trivially_destructible_v<_Type>>
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208 | struct _Uninitialized;
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209 |
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210 | template<typename _Type>
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211 | struct _Uninitialized<_Type, true>
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212 | {
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213 | template<typename... _Args>
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214 | constexpr
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215 | _Uninitialized(in_place_index_t<0>, _Args&&... __args)
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216 | : _M_storage(std::forward<_Args>(__args)...)
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217 | { }
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218 |
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219 | constexpr const _Type& _M_get() const & noexcept
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220 | { return _M_storage; }
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221 |
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222 | constexpr _Type& _M_get() & noexcept
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223 | { return _M_storage; }
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224 |
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225 | constexpr const _Type&& _M_get() const && noexcept
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226 | { return std::move(_M_storage); }
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227 |
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228 | constexpr _Type&& _M_get() && noexcept
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229 | { return std::move(_M_storage); }
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230 |
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231 | _Type _M_storage;
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232 | };
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233 |
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234 | template<typename _Type>
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235 | struct _Uninitialized<_Type, false>
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236 | {
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237 | template<typename... _Args>
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238 | constexpr
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239 | _Uninitialized(in_place_index_t<0>, _Args&&... __args)
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240 | {
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241 | ::new ((void*)std::addressof(_M_storage))
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242 | _Type(std::forward<_Args>(__args)...);
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243 | }
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244 |
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245 | const _Type& _M_get() const & noexcept
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246 | { return *_M_storage._M_ptr(); }
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247 |
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248 | _Type& _M_get() & noexcept
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249 | { return *_M_storage._M_ptr(); }
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250 |
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251 | const _Type&& _M_get() const && noexcept
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252 | { return std::move(*_M_storage._M_ptr()); }
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253 |
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254 | _Type&& _M_get() && noexcept
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255 | { return std::move(*_M_storage._M_ptr()); }
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256 |
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257 | __gnu_cxx::__aligned_membuf<_Type> _M_storage;
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258 | };
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259 |
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260 | template<typename _Union>
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261 | constexpr decltype(auto)
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262 | __get(in_place_index_t<0>, _Union&& __u) noexcept
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263 | { return std::forward<_Union>(__u)._M_first._M_get(); }
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264 |
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265 | template<size_t _Np, typename _Union>
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266 | constexpr decltype(auto)
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267 | __get(in_place_index_t<_Np>, _Union&& __u) noexcept
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268 | {
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269 | return __variant::__get(in_place_index<_Np-1>,
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270 | std::forward<_Union>(__u)._M_rest);
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271 | }
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272 |
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273 | // Returns the typed storage for __v.
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274 | template<size_t _Np, typename _Variant>
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275 | constexpr decltype(auto)
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276 | __get(_Variant&& __v) noexcept
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277 | {
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278 | return __variant::__get(std::in_place_index<_Np>,
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279 | std::forward<_Variant>(__v)._M_u);
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280 | }
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281 |
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282 | template<typename... _Types>
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283 | struct _Traits
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284 | {
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285 | static constexpr bool _S_default_ctor =
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286 | is_default_constructible_v<typename _Nth_type<0, _Types...>::type>;
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287 | static constexpr bool _S_copy_ctor =
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288 | (is_copy_constructible_v<_Types> && ...);
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289 | static constexpr bool _S_move_ctor =
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290 | (is_move_constructible_v<_Types> && ...);
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291 | static constexpr bool _S_copy_assign =
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292 | _S_copy_ctor
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293 | && (is_copy_assignable_v<_Types> && ...);
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294 | static constexpr bool _S_move_assign =
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295 | _S_move_ctor
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296 | && (is_move_assignable_v<_Types> && ...);
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297 |
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298 | static constexpr bool _S_trivial_dtor =
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299 | (is_trivially_destructible_v<_Types> && ...);
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300 | static constexpr bool _S_trivial_copy_ctor =
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301 | (is_trivially_copy_constructible_v<_Types> && ...);
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302 | static constexpr bool _S_trivial_move_ctor =
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303 | (is_trivially_move_constructible_v<_Types> && ...);
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304 | static constexpr bool _S_trivial_copy_assign =
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305 | _S_trivial_dtor && _S_trivial_copy_ctor
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306 | && (is_trivially_copy_assignable_v<_Types> && ...);
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307 | static constexpr bool _S_trivial_move_assign =
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308 | _S_trivial_dtor && _S_trivial_move_ctor
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309 | && (is_trivially_move_assignable_v<_Types> && ...);
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310 |
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311 | // The following nothrow traits are for non-trivial SMFs. Trivial SMFs
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312 | // are always nothrow.
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313 | static constexpr bool _S_nothrow_default_ctor =
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314 | is_nothrow_default_constructible_v<
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315 | typename _Nth_type<0, _Types...>::type>;
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316 | static constexpr bool _S_nothrow_copy_ctor = false;
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317 | static constexpr bool _S_nothrow_move_ctor =
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318 | (is_nothrow_move_constructible_v<_Types> && ...);
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319 | static constexpr bool _S_nothrow_copy_assign = false;
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320 | static constexpr bool _S_nothrow_move_assign =
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321 | _S_nothrow_move_ctor
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322 | && (is_nothrow_move_assignable_v<_Types> && ...);
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323 | };
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324 |
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325 | // Defines members and ctors.
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326 | template<typename... _Types>
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327 | union _Variadic_union { };
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328 |
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329 | template<typename _First, typename... _Rest>
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330 | union _Variadic_union<_First, _Rest...>
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331 | {
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332 | constexpr _Variadic_union() : _M_rest() { }
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333 |
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334 | template<typename... _Args>
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335 | constexpr _Variadic_union(in_place_index_t<0>, _Args&&... __args)
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336 | : _M_first(in_place_index<0>, std::forward<_Args>(__args)...)
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337 | { }
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338 |
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339 | template<size_t _Np, typename... _Args>
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340 | constexpr _Variadic_union(in_place_index_t<_Np>, _Args&&... __args)
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341 | : _M_rest(in_place_index<_Np-1>, std::forward<_Args>(__args)...)
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342 | { }
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343 |
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344 | _Uninitialized<_First> _M_first;
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345 | _Variadic_union<_Rest...> _M_rest;
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346 | };
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347 |
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348 | // _Never_valueless_alt is true for variant alternatives that can
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349 | // always be placed in a variant without it becoming valueless.
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350 |
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351 | // For suitably-small, trivially copyable types we can create temporaries
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352 | // on the stack and then memcpy them into place.
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353 | template<typename _Tp>
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354 | struct _Never_valueless_alt
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355 | : __and_<bool_constant<sizeof(_Tp) <= 256>, is_trivially_copyable<_Tp>>
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356 | { };
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357 |
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358 | // Specialize _Never_valueless_alt for other types which have a
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359 | // non-throwing and cheap move construction and move assignment operator,
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360 | // so that emplacing the type will provide the strong exception-safety
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361 | // guarantee, by creating and moving a temporary.
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362 | // Whether _Never_valueless_alt<T> is true or not affects the ABI of a
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363 | // variant using that alternative, so we can't change the value later!
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364 |
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365 | // True if every alternative in _Types... can be emplaced in a variant
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366 | // without it becoming valueless. If this is true, variant<_Types...>
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367 | // can never be valueless, which enables some minor optimizations.
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368 | template <typename... _Types>
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369 | constexpr bool __never_valueless()
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370 | {
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371 | return _Traits<_Types...>::_S_move_assign
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372 | && (_Never_valueless_alt<_Types>::value && ...);
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373 | }
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374 |
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375 | // Defines index and the dtor, possibly trivial.
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376 | template<bool __trivially_destructible, typename... _Types>
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377 | struct _Variant_storage;
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378 |
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379 | template <typename... _Types>
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380 | using __select_index =
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381 | typename __select_int::_Select_int_base<sizeof...(_Types),
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382 | unsigned char,
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383 | unsigned short>::type::value_type;
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384 |
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385 | template<typename... _Types>
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386 | struct _Variant_storage<false, _Types...>
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387 | {
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388 | constexpr
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389 | _Variant_storage()
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390 | : _M_index(static_cast<__index_type>(variant_npos))
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391 | { }
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392 |
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393 | template<size_t _Np, typename... _Args>
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394 | constexpr
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395 | _Variant_storage(in_place_index_t<_Np>, _Args&&... __args)
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396 | : _M_u(in_place_index<_Np>, std::forward<_Args>(__args)...),
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397 | _M_index{_Np}
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398 | { }
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399 |
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400 | void _M_reset()
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401 | {
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402 | if (!_M_valid()) [[unlikely]]
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403 | return;
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404 |
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405 | std::__do_visit<void>([](auto&& __this_mem) mutable
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406 | {
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407 | std::_Destroy(std::__addressof(__this_mem));
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408 | }, __variant_cast<_Types...>(*this));
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409 |
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410 | _M_index = static_cast<__index_type>(variant_npos);
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411 | }
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412 |
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413 | ~_Variant_storage()
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414 | { _M_reset(); }
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415 |
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416 | void*
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417 | _M_storage() const noexcept
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418 | {
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419 | return const_cast<void*>(static_cast<const void*>(
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420 | std::addressof(_M_u)));
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421 | }
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422 |
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423 | constexpr bool
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424 | _M_valid() const noexcept
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425 | {
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426 | if constexpr (__variant::__never_valueless<_Types...>())
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427 | return true;
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428 | return this->_M_index != __index_type(variant_npos);
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429 | }
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430 |
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431 | _Variadic_union<_Types...> _M_u;
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432 | using __index_type = __select_index<_Types...>;
|
---|
433 | __index_type _M_index;
|
---|
434 | };
|
---|
435 |
|
---|
436 | template<typename... _Types>
|
---|
437 | struct _Variant_storage<true, _Types...>
|
---|
438 | {
|
---|
439 | constexpr
|
---|
440 | _Variant_storage()
|
---|
441 | : _M_index(static_cast<__index_type>(variant_npos))
|
---|
442 | { }
|
---|
443 |
|
---|
444 | template<size_t _Np, typename... _Args>
|
---|
445 | constexpr
|
---|
446 | _Variant_storage(in_place_index_t<_Np>, _Args&&... __args)
|
---|
447 | : _M_u(in_place_index<_Np>, std::forward<_Args>(__args)...),
|
---|
448 | _M_index{_Np}
|
---|
449 | { }
|
---|
450 |
|
---|
451 | void _M_reset() noexcept
|
---|
452 | { _M_index = static_cast<__index_type>(variant_npos); }
|
---|
453 |
|
---|
454 | void*
|
---|
455 | _M_storage() const noexcept
|
---|
456 | {
|
---|
457 | return const_cast<void*>(static_cast<const void*>(
|
---|
458 | std::addressof(_M_u)));
|
---|
459 | }
|
---|
460 |
|
---|
461 | constexpr bool
|
---|
462 | _M_valid() const noexcept
|
---|
463 | {
|
---|
464 | if constexpr (__variant::__never_valueless<_Types...>())
|
---|
465 | return true;
|
---|
466 | return this->_M_index != static_cast<__index_type>(variant_npos);
|
---|
467 | }
|
---|
468 |
|
---|
469 | _Variadic_union<_Types...> _M_u;
|
---|
470 | using __index_type = __select_index<_Types...>;
|
---|
471 | __index_type _M_index;
|
---|
472 | };
|
---|
473 |
|
---|
474 | template<typename... _Types>
|
---|
475 | using _Variant_storage_alias =
|
---|
476 | _Variant_storage<_Traits<_Types...>::_S_trivial_dtor, _Types...>;
|
---|
477 |
|
---|
478 | template<typename _Tp, typename _Up>
|
---|
479 | void __variant_construct_single(_Tp&& __lhs, _Up&& __rhs_mem)
|
---|
480 | {
|
---|
481 | void* __storage = std::addressof(__lhs._M_u);
|
---|
482 | using _Type = remove_reference_t<decltype(__rhs_mem)>;
|
---|
483 | if constexpr (!is_same_v<_Type, __variant_cookie>)
|
---|
484 | ::new (__storage)
|
---|
485 | _Type(std::forward<decltype(__rhs_mem)>(__rhs_mem));
|
---|
486 | }
|
---|
487 |
|
---|
488 | template<typename... _Types, typename _Tp, typename _Up>
|
---|
489 | void __variant_construct(_Tp&& __lhs, _Up&& __rhs)
|
---|
490 | {
|
---|
491 | __lhs._M_index = __rhs._M_index;
|
---|
492 | __variant::__raw_visit([&__lhs](auto&& __rhs_mem) mutable
|
---|
493 | {
|
---|
494 | __variant_construct_single(std::forward<_Tp>(__lhs),
|
---|
495 | std::forward<decltype(__rhs_mem)>(__rhs_mem));
|
---|
496 | }, __variant_cast<_Types...>(std::forward<_Up>(__rhs)));
|
---|
497 | }
|
---|
498 |
|
---|
499 | // The following are (Copy|Move) (ctor|assign) layers for forwarding
|
---|
500 | // triviality and handling non-trivial SMF behaviors.
|
---|
501 |
|
---|
502 | template<bool, typename... _Types>
|
---|
503 | struct _Copy_ctor_base : _Variant_storage_alias<_Types...>
|
---|
504 | {
|
---|
505 | using _Base = _Variant_storage_alias<_Types...>;
|
---|
506 | using _Base::_Base;
|
---|
507 |
|
---|
508 | _Copy_ctor_base(const _Copy_ctor_base& __rhs)
|
---|
509 | noexcept(_Traits<_Types...>::_S_nothrow_copy_ctor)
|
---|
510 | {
|
---|
511 | __variant_construct<_Types...>(*this, __rhs);
|
---|
512 | }
|
---|
513 |
|
---|
514 | _Copy_ctor_base(_Copy_ctor_base&&) = default;
|
---|
515 | _Copy_ctor_base& operator=(const _Copy_ctor_base&) = default;
|
---|
516 | _Copy_ctor_base& operator=(_Copy_ctor_base&&) = default;
|
---|
517 | };
|
---|
518 |
|
---|
519 | template<typename... _Types>
|
---|
520 | struct _Copy_ctor_base<true, _Types...> : _Variant_storage_alias<_Types...>
|
---|
521 | {
|
---|
522 | using _Base = _Variant_storage_alias<_Types...>;
|
---|
523 | using _Base::_Base;
|
---|
524 | };
|
---|
525 |
|
---|
526 | template<typename... _Types>
|
---|
527 | using _Copy_ctor_alias =
|
---|
528 | _Copy_ctor_base<_Traits<_Types...>::_S_trivial_copy_ctor, _Types...>;
|
---|
529 |
|
---|
530 | template<bool, typename... _Types>
|
---|
531 | struct _Move_ctor_base : _Copy_ctor_alias<_Types...>
|
---|
532 | {
|
---|
533 | using _Base = _Copy_ctor_alias<_Types...>;
|
---|
534 | using _Base::_Base;
|
---|
535 |
|
---|
536 | _Move_ctor_base(_Move_ctor_base&& __rhs)
|
---|
537 | noexcept(_Traits<_Types...>::_S_nothrow_move_ctor)
|
---|
538 | {
|
---|
539 | __variant_construct<_Types...>(*this, std::move(__rhs));
|
---|
540 | }
|
---|
541 |
|
---|
542 | template<typename _Up>
|
---|
543 | void _M_destructive_move(unsigned short __rhs_index, _Up&& __rhs)
|
---|
544 | {
|
---|
545 | this->_M_reset();
|
---|
546 | __variant_construct_single(*this, std::forward<_Up>(__rhs));
|
---|
547 | this->_M_index = __rhs_index;
|
---|
548 | }
|
---|
549 |
|
---|
550 | template<typename _Up>
|
---|
551 | void _M_destructive_copy(unsigned short __rhs_index, const _Up& __rhs)
|
---|
552 | {
|
---|
553 | this->_M_reset();
|
---|
554 | __variant_construct_single(*this, __rhs);
|
---|
555 | this->_M_index = __rhs_index;
|
---|
556 | }
|
---|
557 |
|
---|
558 | _Move_ctor_base(const _Move_ctor_base&) = default;
|
---|
559 | _Move_ctor_base& operator=(const _Move_ctor_base&) = default;
|
---|
560 | _Move_ctor_base& operator=(_Move_ctor_base&&) = default;
|
---|
561 | };
|
---|
562 |
|
---|
563 | template<typename... _Types>
|
---|
564 | struct _Move_ctor_base<true, _Types...> : _Copy_ctor_alias<_Types...>
|
---|
565 | {
|
---|
566 | using _Base = _Copy_ctor_alias<_Types...>;
|
---|
567 | using _Base::_Base;
|
---|
568 |
|
---|
569 | template<typename _Up>
|
---|
570 | void _M_destructive_move(unsigned short __rhs_index, _Up&& __rhs)
|
---|
571 | {
|
---|
572 | this->_M_reset();
|
---|
573 | __variant_construct_single(*this, std::forward<_Up>(__rhs));
|
---|
574 | this->_M_index = __rhs_index;
|
---|
575 | }
|
---|
576 |
|
---|
577 | template<typename _Up>
|
---|
578 | void _M_destructive_copy(unsigned short __rhs_index, const _Up& __rhs)
|
---|
579 | {
|
---|
580 | this->_M_reset();
|
---|
581 | __variant_construct_single(*this, __rhs);
|
---|
582 | this->_M_index = __rhs_index;
|
---|
583 | }
|
---|
584 | };
|
---|
585 |
|
---|
586 | template<typename... _Types>
|
---|
587 | using _Move_ctor_alias =
|
---|
588 | _Move_ctor_base<_Traits<_Types...>::_S_trivial_move_ctor, _Types...>;
|
---|
589 |
|
---|
590 | template<bool, typename... _Types>
|
---|
591 | struct _Copy_assign_base : _Move_ctor_alias<_Types...>
|
---|
592 | {
|
---|
593 | using _Base = _Move_ctor_alias<_Types...>;
|
---|
594 | using _Base::_Base;
|
---|
595 |
|
---|
596 | _Copy_assign_base&
|
---|
597 | operator=(const _Copy_assign_base& __rhs)
|
---|
598 | noexcept(_Traits<_Types...>::_S_nothrow_copy_assign)
|
---|
599 | {
|
---|
600 | __variant::__raw_idx_visit(
|
---|
601 | [this](auto&& __rhs_mem, auto __rhs_index) mutable
|
---|
602 | {
|
---|
603 | if constexpr (__rhs_index != variant_npos)
|
---|
604 | {
|
---|
605 | if (this->_M_index == __rhs_index)
|
---|
606 | __variant::__get<__rhs_index>(*this) = __rhs_mem;
|
---|
607 | else
|
---|
608 | {
|
---|
609 | using __rhs_type = __remove_cvref_t<decltype(__rhs_mem)>;
|
---|
610 | if constexpr (is_nothrow_copy_constructible_v<__rhs_type>
|
---|
611 | || !is_nothrow_move_constructible_v<__rhs_type>)
|
---|
612 | // The standard says this->emplace<__rhs_type>(__rhs_mem)
|
---|
613 | // should be used here, but _M_destructive_copy is
|
---|
614 | // equivalent in this case. Either copy construction
|
---|
615 | // doesn't throw, so _M_destructive_copy gives strong
|
---|
616 | // exception safety guarantee, or both copy construction
|
---|
617 | // and move construction can throw, so emplace only gives
|
---|
618 | // basic exception safety anyway.
|
---|
619 | this->_M_destructive_copy(__rhs_index, __rhs_mem);
|
---|
620 | else
|
---|
621 | __variant_cast<_Types...>(*this)
|
---|
622 | = variant<_Types...>(std::in_place_index<__rhs_index>,
|
---|
623 | __rhs_mem);
|
---|
624 | }
|
---|
625 | }
|
---|
626 | else
|
---|
627 | this->_M_reset();
|
---|
628 | }, __variant_cast<_Types...>(__rhs));
|
---|
629 | return *this;
|
---|
630 | }
|
---|
631 |
|
---|
632 | _Copy_assign_base(const _Copy_assign_base&) = default;
|
---|
633 | _Copy_assign_base(_Copy_assign_base&&) = default;
|
---|
634 | _Copy_assign_base& operator=(_Copy_assign_base&&) = default;
|
---|
635 | };
|
---|
636 |
|
---|
637 | template<typename... _Types>
|
---|
638 | struct _Copy_assign_base<true, _Types...> : _Move_ctor_alias<_Types...>
|
---|
639 | {
|
---|
640 | using _Base = _Move_ctor_alias<_Types...>;
|
---|
641 | using _Base::_Base;
|
---|
642 | };
|
---|
643 |
|
---|
644 | template<typename... _Types>
|
---|
645 | using _Copy_assign_alias =
|
---|
646 | _Copy_assign_base<_Traits<_Types...>::_S_trivial_copy_assign, _Types...>;
|
---|
647 |
|
---|
648 | template<bool, typename... _Types>
|
---|
649 | struct _Move_assign_base : _Copy_assign_alias<_Types...>
|
---|
650 | {
|
---|
651 | using _Base = _Copy_assign_alias<_Types...>;
|
---|
652 | using _Base::_Base;
|
---|
653 |
|
---|
654 | _Move_assign_base&
|
---|
655 | operator=(_Move_assign_base&& __rhs)
|
---|
656 | noexcept(_Traits<_Types...>::_S_nothrow_move_assign)
|
---|
657 | {
|
---|
658 | __variant::__raw_idx_visit(
|
---|
659 | [this](auto&& __rhs_mem, auto __rhs_index) mutable
|
---|
660 | {
|
---|
661 | if constexpr (__rhs_index != variant_npos)
|
---|
662 | {
|
---|
663 | if (this->_M_index == __rhs_index)
|
---|
664 | __variant::__get<__rhs_index>(*this) = std::move(__rhs_mem);
|
---|
665 | else
|
---|
666 | __variant_cast<_Types...>(*this)
|
---|
667 | .template emplace<__rhs_index>(std::move(__rhs_mem));
|
---|
668 | }
|
---|
669 | else
|
---|
670 | this->_M_reset();
|
---|
671 | }, __variant_cast<_Types...>(__rhs));
|
---|
672 | return *this;
|
---|
673 | }
|
---|
674 |
|
---|
675 | _Move_assign_base(const _Move_assign_base&) = default;
|
---|
676 | _Move_assign_base(_Move_assign_base&&) = default;
|
---|
677 | _Move_assign_base& operator=(const _Move_assign_base&) = default;
|
---|
678 | };
|
---|
679 |
|
---|
680 | template<typename... _Types>
|
---|
681 | struct _Move_assign_base<true, _Types...> : _Copy_assign_alias<_Types...>
|
---|
682 | {
|
---|
683 | using _Base = _Copy_assign_alias<_Types...>;
|
---|
684 | using _Base::_Base;
|
---|
685 | };
|
---|
686 |
|
---|
687 | template<typename... _Types>
|
---|
688 | using _Move_assign_alias =
|
---|
689 | _Move_assign_base<_Traits<_Types...>::_S_trivial_move_assign, _Types...>;
|
---|
690 |
|
---|
691 | template<typename... _Types>
|
---|
692 | struct _Variant_base : _Move_assign_alias<_Types...>
|
---|
693 | {
|
---|
694 | using _Base = _Move_assign_alias<_Types...>;
|
---|
695 |
|
---|
696 | constexpr
|
---|
697 | _Variant_base()
|
---|
698 | noexcept(_Traits<_Types...>::_S_nothrow_default_ctor)
|
---|
699 | : _Variant_base(in_place_index<0>) { }
|
---|
700 |
|
---|
701 | template<size_t _Np, typename... _Args>
|
---|
702 | constexpr explicit
|
---|
703 | _Variant_base(in_place_index_t<_Np> __i, _Args&&... __args)
|
---|
704 | : _Base(__i, std::forward<_Args>(__args)...)
|
---|
705 | { }
|
---|
706 |
|
---|
707 | _Variant_base(const _Variant_base&) = default;
|
---|
708 | _Variant_base(_Variant_base&&) = default;
|
---|
709 | _Variant_base& operator=(const _Variant_base&) = default;
|
---|
710 | _Variant_base& operator=(_Variant_base&&) = default;
|
---|
711 | };
|
---|
712 |
|
---|
713 | // For how many times does _Tp appear in _Tuple?
|
---|
714 | template<typename _Tp, typename _Tuple>
|
---|
715 | struct __tuple_count;
|
---|
716 |
|
---|
717 | template<typename _Tp, typename _Tuple>
|
---|
718 | inline constexpr size_t __tuple_count_v =
|
---|
719 | __tuple_count<_Tp, _Tuple>::value;
|
---|
720 |
|
---|
721 | template<typename _Tp, typename... _Types>
|
---|
722 | struct __tuple_count<_Tp, tuple<_Types...>>
|
---|
723 | : integral_constant<size_t, 0> { };
|
---|
724 |
|
---|
725 | template<typename _Tp, typename _First, typename... _Rest>
|
---|
726 | struct __tuple_count<_Tp, tuple<_First, _Rest...>>
|
---|
727 | : integral_constant<
|
---|
728 | size_t,
|
---|
729 | __tuple_count_v<_Tp, tuple<_Rest...>> + is_same_v<_Tp, _First>> { };
|
---|
730 |
|
---|
731 | // TODO: Reuse this in <tuple> ?
|
---|
732 | template<typename _Tp, typename... _Types>
|
---|
733 | inline constexpr bool __exactly_once =
|
---|
734 | __tuple_count_v<_Tp, tuple<_Types...>> == 1;
|
---|
735 |
|
---|
736 | // Helper used to check for valid conversions that don't involve narrowing.
|
---|
737 | template<typename _Ti> struct _Arr { _Ti _M_x[1]; };
|
---|
738 |
|
---|
739 | // "Build an imaginary function FUN(Ti) for each alternative type Ti"
|
---|
740 | template<size_t _Ind, typename _Tp, typename _Ti, typename = void>
|
---|
741 | struct _Build_FUN
|
---|
742 | {
|
---|
743 | // This function means 'using _Build_FUN<I, T, Ti>::_S_fun;' is valid,
|
---|
744 | // but only static functions will be considered in the call below.
|
---|
745 | void _S_fun();
|
---|
746 | };
|
---|
747 |
|
---|
748 | // "... for which Ti x[] = {std::forward<T>(t)}; is well-formed."
|
---|
749 | template<size_t _Ind, typename _Tp, typename _Ti>
|
---|
750 | struct _Build_FUN<_Ind, _Tp, _Ti,
|
---|
751 | void_t<decltype(_Arr<_Ti>{{std::declval<_Tp>()}})>>
|
---|
752 | {
|
---|
753 | // This is the FUN function for type _Ti, with index _Ind
|
---|
754 | static integral_constant<size_t, _Ind> _S_fun(_Ti);
|
---|
755 | };
|
---|
756 |
|
---|
757 | template<typename _Tp, typename _Variant,
|
---|
758 | typename = make_index_sequence<variant_size_v<_Variant>>>
|
---|
759 | struct _Build_FUNs;
|
---|
760 |
|
---|
761 | template<typename _Tp, typename... _Ti, size_t... _Ind>
|
---|
762 | struct _Build_FUNs<_Tp, variant<_Ti...>, index_sequence<_Ind...>>
|
---|
763 | : _Build_FUN<_Ind, _Tp, _Ti>...
|
---|
764 | {
|
---|
765 | using _Build_FUN<_Ind, _Tp, _Ti>::_S_fun...;
|
---|
766 | };
|
---|
767 |
|
---|
768 | // The index j of the overload FUN(Tj) selected by overload resolution
|
---|
769 | // for FUN(std::forward<_Tp>(t))
|
---|
770 | template<typename _Tp, typename _Variant>
|
---|
771 | using _FUN_type
|
---|
772 | = decltype(_Build_FUNs<_Tp, _Variant>::_S_fun(std::declval<_Tp>()));
|
---|
773 |
|
---|
774 | // The index selected for FUN(std::forward<T>(t)), or variant_npos if none.
|
---|
775 | template<typename _Tp, typename _Variant, typename = void>
|
---|
776 | struct __accepted_index
|
---|
777 | : integral_constant<size_t, variant_npos>
|
---|
778 | { };
|
---|
779 |
|
---|
780 | template<typename _Tp, typename _Variant>
|
---|
781 | struct __accepted_index<_Tp, _Variant, void_t<_FUN_type<_Tp, _Variant>>>
|
---|
782 | : _FUN_type<_Tp, _Variant>
|
---|
783 | { };
|
---|
784 |
|
---|
785 | // Returns the raw storage for __v.
|
---|
786 | template<typename _Variant>
|
---|
787 | void* __get_storage(_Variant&& __v) noexcept
|
---|
788 | { return __v._M_storage(); }
|
---|
789 |
|
---|
790 | template <typename _Maybe_variant_cookie, typename _Variant>
|
---|
791 | struct _Extra_visit_slot_needed
|
---|
792 | {
|
---|
793 | template <typename> struct _Variant_never_valueless;
|
---|
794 |
|
---|
795 | template <typename... _Types>
|
---|
796 | struct _Variant_never_valueless<variant<_Types...>>
|
---|
797 | : bool_constant<__variant::__never_valueless<_Types...>()> {};
|
---|
798 |
|
---|
799 | static constexpr bool value =
|
---|
800 | (is_same_v<_Maybe_variant_cookie, __variant_cookie>
|
---|
801 | || is_same_v<_Maybe_variant_cookie, __variant_idx_cookie>)
|
---|
802 | && !_Variant_never_valueless<__remove_cvref_t<_Variant>>::value;
|
---|
803 | };
|
---|
804 |
|
---|
805 | // Used for storing a multi-dimensional vtable.
|
---|
806 | template<typename _Tp, size_t... _Dimensions>
|
---|
807 | struct _Multi_array;
|
---|
808 |
|
---|
809 | // Partial specialization with rank zero, stores a single _Tp element.
|
---|
810 | template<typename _Tp>
|
---|
811 | struct _Multi_array<_Tp>
|
---|
812 | {
|
---|
813 | template<typename>
|
---|
814 | struct __untag_result
|
---|
815 | : false_type
|
---|
816 | { using element_type = _Tp; };
|
---|
817 |
|
---|
818 | template <typename... _Args>
|
---|
819 | struct __untag_result<const void(*)(_Args...)>
|
---|
820 | : false_type
|
---|
821 | { using element_type = void(*)(_Args...); };
|
---|
822 |
|
---|
823 | template <typename... _Args>
|
---|
824 | struct __untag_result<__variant_cookie(*)(_Args...)>
|
---|
825 | : false_type
|
---|
826 | { using element_type = void(*)(_Args...); };
|
---|
827 |
|
---|
828 | template <typename... _Args>
|
---|
829 | struct __untag_result<__variant_idx_cookie(*)(_Args...)>
|
---|
830 | : false_type
|
---|
831 | { using element_type = void(*)(_Args...); };
|
---|
832 |
|
---|
833 | template <typename _Res, typename... _Args>
|
---|
834 | struct __untag_result<__deduce_visit_result<_Res>(*)(_Args...)>
|
---|
835 | : true_type
|
---|
836 | { using element_type = _Res(*)(_Args...); };
|
---|
837 |
|
---|
838 | using __result_is_deduced = __untag_result<_Tp>;
|
---|
839 |
|
---|
840 | constexpr const typename __untag_result<_Tp>::element_type&
|
---|
841 | _M_access() const
|
---|
842 | { return _M_data; }
|
---|
843 |
|
---|
844 | typename __untag_result<_Tp>::element_type _M_data;
|
---|
845 | };
|
---|
846 |
|
---|
847 | // Partial specialization with rank >= 1.
|
---|
848 | template<typename _Ret,
|
---|
849 | typename _Visitor,
|
---|
850 | typename... _Variants,
|
---|
851 | size_t __first, size_t... __rest>
|
---|
852 | struct _Multi_array<_Ret(*)(_Visitor, _Variants...), __first, __rest...>
|
---|
853 | {
|
---|
854 | static constexpr size_t __index =
|
---|
855 | sizeof...(_Variants) - sizeof...(__rest) - 1;
|
---|
856 |
|
---|
857 | using _Variant = typename _Nth_type<__index, _Variants...>::type;
|
---|
858 |
|
---|
859 | static constexpr int __do_cookie =
|
---|
860 | _Extra_visit_slot_needed<_Ret, _Variant>::value ? 1 : 0;
|
---|
861 |
|
---|
862 | using _Tp = _Ret(*)(_Visitor, _Variants...);
|
---|
863 |
|
---|
864 | template<typename... _Args>
|
---|
865 | constexpr decltype(auto)
|
---|
866 | _M_access(size_t __first_index, _Args... __rest_indices) const
|
---|
867 | {
|
---|
868 | return _M_arr[__first_index + __do_cookie]
|
---|
869 | ._M_access(__rest_indices...);
|
---|
870 | }
|
---|
871 |
|
---|
872 | _Multi_array<_Tp, __rest...> _M_arr[__first + __do_cookie];
|
---|
873 | };
|
---|
874 |
|
---|
875 | // Creates a multi-dimensional vtable recursively.
|
---|
876 | //
|
---|
877 | // For example,
|
---|
878 | // visit([](auto, auto){},
|
---|
879 | // variant<int, char>(), // typedef'ed as V1
|
---|
880 | // variant<float, double, long double>()) // typedef'ed as V2
|
---|
881 | // will trigger instantiations of:
|
---|
882 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&), 2, 3>,
|
---|
883 | // tuple<V1&&, V2&&>, std::index_sequence<>>
|
---|
884 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&), 3>,
|
---|
885 | // tuple<V1&&, V2&&>, std::index_sequence<0>>
|
---|
886 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>,
|
---|
887 | // tuple<V1&&, V2&&>, std::index_sequence<0, 0>>
|
---|
888 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>,
|
---|
889 | // tuple<V1&&, V2&&>, std::index_sequence<0, 1>>
|
---|
890 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>,
|
---|
891 | // tuple<V1&&, V2&&>, std::index_sequence<0, 2>>
|
---|
892 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&), 3>,
|
---|
893 | // tuple<V1&&, V2&&>, std::index_sequence<1>>
|
---|
894 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>,
|
---|
895 | // tuple<V1&&, V2&&>, std::index_sequence<1, 0>>
|
---|
896 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>,
|
---|
897 | // tuple<V1&&, V2&&>, std::index_sequence<1, 1>>
|
---|
898 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>,
|
---|
899 | // tuple<V1&&, V2&&>, std::index_sequence<1, 2>>
|
---|
900 | // The returned multi-dimensional vtable can be fast accessed by the visitor
|
---|
901 | // using index calculation.
|
---|
902 | template<typename _Array_type, typename _Index_seq>
|
---|
903 | struct __gen_vtable_impl;
|
---|
904 |
|
---|
905 | // Defines the _S_apply() member that returns a _Multi_array populated
|
---|
906 | // with function pointers that perform the visitation expressions e(m)
|
---|
907 | // for each valid pack of indexes into the variant types _Variants.
|
---|
908 | //
|
---|
909 | // This partial specialization builds up the index sequences by recursively
|
---|
910 | // calling _S_apply() on the next specialization of __gen_vtable_impl.
|
---|
911 | // The base case of the recursion defines the actual function pointers.
|
---|
912 | template<typename _Result_type, typename _Visitor, size_t... __dimensions,
|
---|
913 | typename... _Variants, size_t... __indices>
|
---|
914 | struct __gen_vtable_impl<
|
---|
915 | _Multi_array<_Result_type (*)(_Visitor, _Variants...), __dimensions...>,
|
---|
916 | std::index_sequence<__indices...>>
|
---|
917 | {
|
---|
918 | using _Next =
|
---|
919 | remove_reference_t<typename _Nth_type<sizeof...(__indices),
|
---|
920 | _Variants...>::type>;
|
---|
921 | using _Array_type =
|
---|
922 | _Multi_array<_Result_type (*)(_Visitor, _Variants...),
|
---|
923 | __dimensions...>;
|
---|
924 |
|
---|
925 | static constexpr _Array_type
|
---|
926 | _S_apply()
|
---|
927 | {
|
---|
928 | _Array_type __vtable{};
|
---|
929 | _S_apply_all_alts(
|
---|
930 | __vtable, make_index_sequence<variant_size_v<_Next>>());
|
---|
931 | return __vtable;
|
---|
932 | }
|
---|
933 |
|
---|
934 | template<size_t... __var_indices>
|
---|
935 | static constexpr void
|
---|
936 | _S_apply_all_alts(_Array_type& __vtable,
|
---|
937 | std::index_sequence<__var_indices...>)
|
---|
938 | {
|
---|
939 | if constexpr (_Extra_visit_slot_needed<_Result_type, _Next>::value)
|
---|
940 | (_S_apply_single_alt<true, __var_indices>(
|
---|
941 | __vtable._M_arr[__var_indices + 1],
|
---|
942 | &(__vtable._M_arr[0])), ...);
|
---|
943 | else
|
---|
944 | (_S_apply_single_alt<false, __var_indices>(
|
---|
945 | __vtable._M_arr[__var_indices]), ...);
|
---|
946 | }
|
---|
947 |
|
---|
948 | template<bool __do_cookie, size_t __index, typename _Tp>
|
---|
949 | static constexpr void
|
---|
950 | _S_apply_single_alt(_Tp& __element, _Tp* __cookie_element = nullptr)
|
---|
951 | {
|
---|
952 | if constexpr (__do_cookie)
|
---|
953 | {
|
---|
954 | __element = __gen_vtable_impl<
|
---|
955 | _Tp,
|
---|
956 | std::index_sequence<__indices..., __index>>::_S_apply();
|
---|
957 | *__cookie_element = __gen_vtable_impl<
|
---|
958 | _Tp,
|
---|
959 | std::index_sequence<__indices..., variant_npos>>::_S_apply();
|
---|
960 | }
|
---|
961 | else
|
---|
962 | {
|
---|
963 | auto __tmp_element = __gen_vtable_impl<
|
---|
964 | remove_reference_t<decltype(__element)>,
|
---|
965 | std::index_sequence<__indices..., __index>>::_S_apply();
|
---|
966 | static_assert(is_same_v<_Tp, decltype(__tmp_element)>,
|
---|
967 | "std::visit requires the visitor to have the same "
|
---|
968 | "return type for all alternatives of a variant");
|
---|
969 | __element = __tmp_element;
|
---|
970 | }
|
---|
971 | }
|
---|
972 | };
|
---|
973 |
|
---|
974 | // This partial specialization is the base case for the recursion.
|
---|
975 | // It populates a _Multi_array element with the address of a function
|
---|
976 | // that invokes the visitor with the alternatives specified by __indices.
|
---|
977 | template<typename _Result_type, typename _Visitor, typename... _Variants,
|
---|
978 | size_t... __indices>
|
---|
979 | struct __gen_vtable_impl<
|
---|
980 | _Multi_array<_Result_type (*)(_Visitor, _Variants...)>,
|
---|
981 | std::index_sequence<__indices...>>
|
---|
982 | {
|
---|
983 | using _Array_type =
|
---|
984 | _Multi_array<_Result_type (*)(_Visitor, _Variants...)>;
|
---|
985 |
|
---|
986 | template<size_t __index, typename _Variant>
|
---|
987 | static constexpr decltype(auto)
|
---|
988 | __element_by_index_or_cookie(_Variant&& __var) noexcept
|
---|
989 | {
|
---|
990 | if constexpr (__index != variant_npos)
|
---|
991 | return __variant::__get<__index>(std::forward<_Variant>(__var));
|
---|
992 | else
|
---|
993 | return __variant_cookie{};
|
---|
994 | }
|
---|
995 |
|
---|
996 | static constexpr decltype(auto)
|
---|
997 | __visit_invoke(_Visitor&& __visitor, _Variants... __vars)
|
---|
998 | {
|
---|
999 | if constexpr (is_same_v<_Result_type, __variant_idx_cookie>)
|
---|
1000 | // For raw visitation using indices, pass the indices to the visitor
|
---|
1001 | // and discard the return value:
|
---|
1002 | std::__invoke(std::forward<_Visitor>(__visitor),
|
---|
1003 | __element_by_index_or_cookie<__indices>(
|
---|
1004 | std::forward<_Variants>(__vars))...,
|
---|
1005 | integral_constant<size_t, __indices>()...);
|
---|
1006 | else if constexpr (is_same_v<_Result_type, __variant_cookie>)
|
---|
1007 | // For raw visitation without indices, and discard the return value:
|
---|
1008 | std::__invoke(std::forward<_Visitor>(__visitor),
|
---|
1009 | __element_by_index_or_cookie<__indices>(
|
---|
1010 | std::forward<_Variants>(__vars))...);
|
---|
1011 | else if constexpr (_Array_type::__result_is_deduced::value)
|
---|
1012 | // For the usual std::visit case deduce the return value:
|
---|
1013 | return std::__invoke(std::forward<_Visitor>(__visitor),
|
---|
1014 | __element_by_index_or_cookie<__indices>(
|
---|
1015 | std::forward<_Variants>(__vars))...);
|
---|
1016 | else // for std::visit<R> use INVOKE<R>
|
---|
1017 | return std::__invoke_r<_Result_type>(
|
---|
1018 | std::forward<_Visitor>(__visitor),
|
---|
1019 | __variant::__get<__indices>(std::forward<_Variants>(__vars))...);
|
---|
1020 | }
|
---|
1021 |
|
---|
1022 | static constexpr auto
|
---|
1023 | _S_apply()
|
---|
1024 | {
|
---|
1025 | if constexpr (_Array_type::__result_is_deduced::value)
|
---|
1026 | {
|
---|
1027 | constexpr bool __visit_ret_type_mismatch =
|
---|
1028 | !is_same_v<typename _Result_type::type,
|
---|
1029 | decltype(__visit_invoke(std::declval<_Visitor>(),
|
---|
1030 | std::declval<_Variants>()...))>;
|
---|
1031 | if constexpr (__visit_ret_type_mismatch)
|
---|
1032 | {
|
---|
1033 | struct __cannot_match {};
|
---|
1034 | return __cannot_match{};
|
---|
1035 | }
|
---|
1036 | else
|
---|
1037 | return _Array_type{&__visit_invoke};
|
---|
1038 | }
|
---|
1039 | else
|
---|
1040 | return _Array_type{&__visit_invoke};
|
---|
1041 | }
|
---|
1042 | };
|
---|
1043 |
|
---|
1044 | template<typename _Result_type, typename _Visitor, typename... _Variants>
|
---|
1045 | struct __gen_vtable
|
---|
1046 | {
|
---|
1047 | using _Array_type =
|
---|
1048 | _Multi_array<_Result_type (*)(_Visitor, _Variants...),
|
---|
1049 | variant_size_v<remove_reference_t<_Variants>>...>;
|
---|
1050 |
|
---|
1051 | static constexpr _Array_type _S_vtable
|
---|
1052 | = __gen_vtable_impl<_Array_type, std::index_sequence<>>::_S_apply();
|
---|
1053 | };
|
---|
1054 |
|
---|
1055 | template<size_t _Np, typename _Tp>
|
---|
1056 | struct _Base_dedup : public _Tp { };
|
---|
1057 |
|
---|
1058 | template<typename _Variant, typename __indices>
|
---|
1059 | struct _Variant_hash_base;
|
---|
1060 |
|
---|
1061 | template<typename... _Types, size_t... __indices>
|
---|
1062 | struct _Variant_hash_base<variant<_Types...>,
|
---|
1063 | std::index_sequence<__indices...>>
|
---|
1064 | : _Base_dedup<__indices, __poison_hash<remove_const_t<_Types>>>... { };
|
---|
1065 |
|
---|
1066 | template<size_t _Np, typename _Variant>
|
---|
1067 | using __get_t = decltype(std::get<_Np>(std::declval<_Variant>()));
|
---|
1068 |
|
---|
1069 | // Return type of std::visit.
|
---|
1070 | template<typename _Visitor, typename... _Variants>
|
---|
1071 | using __visit_result_t
|
---|
1072 | = invoke_result_t<_Visitor, __get_t<0, _Variants>...>;
|
---|
1073 |
|
---|
1074 | template<typename _Tp, typename... _Types>
|
---|
1075 | constexpr inline bool __same_types = (is_same_v<_Tp, _Types> && ...);
|
---|
1076 |
|
---|
1077 | template <typename _Visitor, typename _Variant, size_t... _Idxs>
|
---|
1078 | constexpr bool __check_visitor_results(std::index_sequence<_Idxs...>)
|
---|
1079 | {
|
---|
1080 | return __same_types<
|
---|
1081 | invoke_result_t<_Visitor, __get_t<_Idxs, _Variant>>...
|
---|
1082 | >;
|
---|
1083 | }
|
---|
1084 |
|
---|
1085 | } // namespace __variant
|
---|
1086 | } // namespace __detail
|
---|
1087 |
|
---|
1088 | template<size_t _Np, typename _Variant, typename... _Args>
|
---|
1089 | void __variant_construct_by_index(_Variant& __v, _Args&&... __args)
|
---|
1090 | {
|
---|
1091 | __v._M_index = _Np;
|
---|
1092 | auto&& __storage = __detail::__variant::__get<_Np>(__v);
|
---|
1093 | ::new ((void*)std::addressof(__storage))
|
---|
1094 | remove_reference_t<decltype(__storage)>
|
---|
1095 | (std::forward<_Args>(__args)...);
|
---|
1096 | }
|
---|
1097 |
|
---|
1098 | template<typename _Tp, typename... _Types>
|
---|
1099 | constexpr bool
|
---|
1100 | holds_alternative(const variant<_Types...>& __v) noexcept
|
---|
1101 | {
|
---|
1102 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
|
---|
1103 | "T must occur exactly once in alternatives");
|
---|
1104 | return __v.index() == __detail::__variant::__index_of_v<_Tp, _Types...>;
|
---|
1105 | }
|
---|
1106 |
|
---|
1107 | template<typename _Tp, typename... _Types>
|
---|
1108 | constexpr _Tp& get(variant<_Types...>& __v)
|
---|
1109 | {
|
---|
1110 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
|
---|
1111 | "T must occur exactly once in alternatives");
|
---|
1112 | static_assert(!is_void_v<_Tp>, "_Tp must not be void");
|
---|
1113 | return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v);
|
---|
1114 | }
|
---|
1115 |
|
---|
1116 | template<typename _Tp, typename... _Types>
|
---|
1117 | constexpr _Tp&& get(variant<_Types...>&& __v)
|
---|
1118 | {
|
---|
1119 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
|
---|
1120 | "T must occur exactly once in alternatives");
|
---|
1121 | static_assert(!is_void_v<_Tp>, "_Tp must not be void");
|
---|
1122 | return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(
|
---|
1123 | std::move(__v));
|
---|
1124 | }
|
---|
1125 |
|
---|
1126 | template<typename _Tp, typename... _Types>
|
---|
1127 | constexpr const _Tp& get(const variant<_Types...>& __v)
|
---|
1128 | {
|
---|
1129 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
|
---|
1130 | "T must occur exactly once in alternatives");
|
---|
1131 | static_assert(!is_void_v<_Tp>, "_Tp must not be void");
|
---|
1132 | return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v);
|
---|
1133 | }
|
---|
1134 |
|
---|
1135 | template<typename _Tp, typename... _Types>
|
---|
1136 | constexpr const _Tp&& get(const variant<_Types...>&& __v)
|
---|
1137 | {
|
---|
1138 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
|
---|
1139 | "T must occur exactly once in alternatives");
|
---|
1140 | static_assert(!is_void_v<_Tp>, "_Tp must not be void");
|
---|
1141 | return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(
|
---|
1142 | std::move(__v));
|
---|
1143 | }
|
---|
1144 |
|
---|
1145 | template<size_t _Np, typename... _Types>
|
---|
1146 | constexpr add_pointer_t<variant_alternative_t<_Np, variant<_Types...>>>
|
---|
1147 | get_if(variant<_Types...>* __ptr) noexcept
|
---|
1148 | {
|
---|
1149 | using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>;
|
---|
1150 | static_assert(_Np < sizeof...(_Types),
|
---|
1151 | "The index must be in [0, number of alternatives)");
|
---|
1152 | static_assert(!is_void_v<_Alternative_type>, "_Tp must not be void");
|
---|
1153 | if (__ptr && __ptr->index() == _Np)
|
---|
1154 | return std::addressof(__detail::__variant::__get<_Np>(*__ptr));
|
---|
1155 | return nullptr;
|
---|
1156 | }
|
---|
1157 |
|
---|
1158 | template<size_t _Np, typename... _Types>
|
---|
1159 | constexpr
|
---|
1160 | add_pointer_t<const variant_alternative_t<_Np, variant<_Types...>>>
|
---|
1161 | get_if(const variant<_Types...>* __ptr) noexcept
|
---|
1162 | {
|
---|
1163 | using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>;
|
---|
1164 | static_assert(_Np < sizeof...(_Types),
|
---|
1165 | "The index must be in [0, number of alternatives)");
|
---|
1166 | static_assert(!is_void_v<_Alternative_type>, "_Tp must not be void");
|
---|
1167 | if (__ptr && __ptr->index() == _Np)
|
---|
1168 | return std::addressof(__detail::__variant::__get<_Np>(*__ptr));
|
---|
1169 | return nullptr;
|
---|
1170 | }
|
---|
1171 |
|
---|
1172 | template<typename _Tp, typename... _Types>
|
---|
1173 | constexpr add_pointer_t<_Tp>
|
---|
1174 | get_if(variant<_Types...>* __ptr) noexcept
|
---|
1175 | {
|
---|
1176 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
|
---|
1177 | "T must occur exactly once in alternatives");
|
---|
1178 | static_assert(!is_void_v<_Tp>, "_Tp must not be void");
|
---|
1179 | return std::get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>(
|
---|
1180 | __ptr);
|
---|
1181 | }
|
---|
1182 |
|
---|
1183 | template<typename _Tp, typename... _Types>
|
---|
1184 | constexpr add_pointer_t<const _Tp>
|
---|
1185 | get_if(const variant<_Types...>* __ptr) noexcept
|
---|
1186 | {
|
---|
1187 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
|
---|
1188 | "T must occur exactly once in alternatives");
|
---|
1189 | static_assert(!is_void_v<_Tp>, "_Tp must not be void");
|
---|
1190 | return std::get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>(
|
---|
1191 | __ptr);
|
---|
1192 | }
|
---|
1193 |
|
---|
1194 | struct monostate { };
|
---|
1195 |
|
---|
1196 | #define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP, __NAME) \
|
---|
1197 | template<typename... _Types> \
|
---|
1198 | constexpr bool operator __OP(const variant<_Types...>& __lhs, \
|
---|
1199 | const variant<_Types...>& __rhs) \
|
---|
1200 | { \
|
---|
1201 | bool __ret = true; \
|
---|
1202 | __detail::__variant::__raw_idx_visit( \
|
---|
1203 | [&__ret, &__lhs] (auto&& __rhs_mem, auto __rhs_index) mutable \
|
---|
1204 | { \
|
---|
1205 | if constexpr (__rhs_index != variant_npos) \
|
---|
1206 | { \
|
---|
1207 | if (__lhs.index() == __rhs_index) \
|
---|
1208 | { \
|
---|
1209 | auto& __this_mem = std::get<__rhs_index>(__lhs); \
|
---|
1210 | __ret = __this_mem __OP __rhs_mem; \
|
---|
1211 | } \
|
---|
1212 | else \
|
---|
1213 | __ret = (__lhs.index() + 1) __OP (__rhs_index + 1); \
|
---|
1214 | } \
|
---|
1215 | else \
|
---|
1216 | __ret = (__lhs.index() + 1) __OP (__rhs_index + 1); \
|
---|
1217 | }, __rhs); \
|
---|
1218 | return __ret; \
|
---|
1219 | }
|
---|
1220 |
|
---|
1221 | _VARIANT_RELATION_FUNCTION_TEMPLATE(<, less)
|
---|
1222 | _VARIANT_RELATION_FUNCTION_TEMPLATE(<=, less_equal)
|
---|
1223 | _VARIANT_RELATION_FUNCTION_TEMPLATE(==, equal)
|
---|
1224 | _VARIANT_RELATION_FUNCTION_TEMPLATE(!=, not_equal)
|
---|
1225 | _VARIANT_RELATION_FUNCTION_TEMPLATE(>=, greater_equal)
|
---|
1226 | _VARIANT_RELATION_FUNCTION_TEMPLATE(>, greater)
|
---|
1227 |
|
---|
1228 | #undef _VARIANT_RELATION_FUNCTION_TEMPLATE
|
---|
1229 |
|
---|
1230 | constexpr bool operator==(monostate, monostate) noexcept { return true; }
|
---|
1231 |
|
---|
1232 | #ifdef __cpp_lib_three_way_comparison
|
---|
1233 | template<typename... _Types>
|
---|
1234 | requires (three_way_comparable<_Types> && ...)
|
---|
1235 | constexpr
|
---|
1236 | common_comparison_category_t<compare_three_way_result_t<_Types>...>
|
---|
1237 | operator<=>(const variant<_Types...>& __v, const variant<_Types...>& __w)
|
---|
1238 | {
|
---|
1239 | common_comparison_category_t<compare_three_way_result_t<_Types>...> __ret
|
---|
1240 | = strong_ordering::equal;
|
---|
1241 |
|
---|
1242 | __detail::__variant::__raw_idx_visit(
|
---|
1243 | [&__ret, &__v] (auto&& __w_mem, auto __w_index) mutable
|
---|
1244 | {
|
---|
1245 | if constexpr (__w_index != variant_npos)
|
---|
1246 | {
|
---|
1247 | if (__v.index() == __w_index)
|
---|
1248 | {
|
---|
1249 | auto& __this_mem = std::get<__w_index>(__v);
|
---|
1250 | __ret = __this_mem <=> __w_mem;
|
---|
1251 | return;
|
---|
1252 | }
|
---|
1253 | }
|
---|
1254 | __ret = (__v.index() + 1) <=> (__w_index + 1);
|
---|
1255 | }, __w);
|
---|
1256 | return __ret;
|
---|
1257 | }
|
---|
1258 |
|
---|
1259 | constexpr strong_ordering
|
---|
1260 | operator<=>(monostate, monostate) noexcept { return strong_ordering::equal; }
|
---|
1261 | #else
|
---|
1262 | constexpr bool operator!=(monostate, monostate) noexcept { return false; }
|
---|
1263 | constexpr bool operator<(monostate, monostate) noexcept { return false; }
|
---|
1264 | constexpr bool operator>(monostate, monostate) noexcept { return false; }
|
---|
1265 | constexpr bool operator<=(monostate, monostate) noexcept { return true; }
|
---|
1266 | constexpr bool operator>=(monostate, monostate) noexcept { return true; }
|
---|
1267 | #endif
|
---|
1268 |
|
---|
1269 | template<typename _Visitor, typename... _Variants>
|
---|
1270 | constexpr __detail::__variant::__visit_result_t<_Visitor, _Variants...>
|
---|
1271 | visit(_Visitor&&, _Variants&&...);
|
---|
1272 |
|
---|
1273 | template<typename... _Types>
|
---|
1274 | inline enable_if_t<(is_move_constructible_v<_Types> && ...)
|
---|
1275 | && (is_swappable_v<_Types> && ...)>
|
---|
1276 | swap(variant<_Types...>& __lhs, variant<_Types...>& __rhs)
|
---|
1277 | noexcept(noexcept(__lhs.swap(__rhs)))
|
---|
1278 | { __lhs.swap(__rhs); }
|
---|
1279 |
|
---|
1280 | template<typename... _Types>
|
---|
1281 | enable_if_t<!((is_move_constructible_v<_Types> && ...)
|
---|
1282 | && (is_swappable_v<_Types> && ...))>
|
---|
1283 | swap(variant<_Types...>&, variant<_Types...>&) = delete;
|
---|
1284 |
|
---|
1285 | class bad_variant_access : public exception
|
---|
1286 | {
|
---|
1287 | public:
|
---|
1288 | bad_variant_access() noexcept { }
|
---|
1289 |
|
---|
1290 | const char* what() const noexcept override
|
---|
1291 | { return _M_reason; }
|
---|
1292 |
|
---|
1293 | private:
|
---|
1294 | bad_variant_access(const char* __reason) noexcept : _M_reason(__reason) { }
|
---|
1295 |
|
---|
1296 | // Must point to a string with static storage duration:
|
---|
1297 | const char* _M_reason = "bad variant access";
|
---|
1298 |
|
---|
1299 | friend void __throw_bad_variant_access(const char* __what);
|
---|
1300 | };
|
---|
1301 |
|
---|
1302 | // Must only be called with a string literal
|
---|
1303 | inline void
|
---|
1304 | __throw_bad_variant_access(const char* __what)
|
---|
1305 | { _GLIBCXX_THROW_OR_ABORT(bad_variant_access(__what)); }
|
---|
1306 |
|
---|
1307 | inline void
|
---|
1308 | __throw_bad_variant_access(bool __valueless)
|
---|
1309 | {
|
---|
1310 | if (__valueless) [[__unlikely__]]
|
---|
1311 | __throw_bad_variant_access("std::get: variant is valueless");
|
---|
1312 | else
|
---|
1313 | __throw_bad_variant_access("std::get: wrong index for variant");
|
---|
1314 | }
|
---|
1315 |
|
---|
1316 | template<typename... _Types>
|
---|
1317 | class variant
|
---|
1318 | : private __detail::__variant::_Variant_base<_Types...>,
|
---|
1319 | private _Enable_default_constructor<
|
---|
1320 | __detail::__variant::_Traits<_Types...>::_S_default_ctor,
|
---|
1321 | variant<_Types...>>,
|
---|
1322 | private _Enable_copy_move<
|
---|
1323 | __detail::__variant::_Traits<_Types...>::_S_copy_ctor,
|
---|
1324 | __detail::__variant::_Traits<_Types...>::_S_copy_assign,
|
---|
1325 | __detail::__variant::_Traits<_Types...>::_S_move_ctor,
|
---|
1326 | __detail::__variant::_Traits<_Types...>::_S_move_assign,
|
---|
1327 | variant<_Types...>>
|
---|
1328 | {
|
---|
1329 | private:
|
---|
1330 | template <typename... _UTypes, typename _Tp>
|
---|
1331 | friend decltype(auto) __variant_cast(_Tp&&);
|
---|
1332 | template<size_t _Np, typename _Variant, typename... _Args>
|
---|
1333 | friend void __variant_construct_by_index(_Variant& __v,
|
---|
1334 | _Args&&... __args);
|
---|
1335 |
|
---|
1336 | static_assert(sizeof...(_Types) > 0,
|
---|
1337 | "variant must have at least one alternative");
|
---|
1338 | static_assert(!(std::is_reference_v<_Types> || ...),
|
---|
1339 | "variant must have no reference alternative");
|
---|
1340 | static_assert(!(std::is_void_v<_Types> || ...),
|
---|
1341 | "variant must have no void alternative");
|
---|
1342 |
|
---|
1343 | using _Base = __detail::__variant::_Variant_base<_Types...>;
|
---|
1344 | using _Default_ctor_enabler =
|
---|
1345 | _Enable_default_constructor<
|
---|
1346 | __detail::__variant::_Traits<_Types...>::_S_default_ctor,
|
---|
1347 | variant<_Types...>>;
|
---|
1348 |
|
---|
1349 | template<typename _Tp>
|
---|
1350 | static constexpr bool __not_self
|
---|
1351 | = !is_same_v<__remove_cvref_t<_Tp>, variant>;
|
---|
1352 |
|
---|
1353 | template<typename _Tp>
|
---|
1354 | static constexpr bool
|
---|
1355 | __exactly_once = __detail::__variant::__exactly_once<_Tp, _Types...>;
|
---|
1356 |
|
---|
1357 | template<typename _Tp>
|
---|
1358 | static constexpr size_t __accepted_index
|
---|
1359 | = __detail::__variant::__accepted_index<_Tp, variant>::value;
|
---|
1360 |
|
---|
1361 | template<size_t _Np, typename = enable_if_t<(_Np < sizeof...(_Types))>>
|
---|
1362 | using __to_type = variant_alternative_t<_Np, variant>;
|
---|
1363 |
|
---|
1364 | template<typename _Tp, typename = enable_if_t<__not_self<_Tp>>>
|
---|
1365 | using __accepted_type = __to_type<__accepted_index<_Tp>>;
|
---|
1366 |
|
---|
1367 | template<typename _Tp>
|
---|
1368 | static constexpr size_t __index_of =
|
---|
1369 | __detail::__variant::__index_of_v<_Tp, _Types...>;
|
---|
1370 |
|
---|
1371 | using _Traits = __detail::__variant::_Traits<_Types...>;
|
---|
1372 |
|
---|
1373 | template<typename _Tp>
|
---|
1374 | struct __is_in_place_tag : false_type { };
|
---|
1375 | template<typename _Tp>
|
---|
1376 | struct __is_in_place_tag<in_place_type_t<_Tp>> : true_type { };
|
---|
1377 | template<size_t _Np>
|
---|
1378 | struct __is_in_place_tag<in_place_index_t<_Np>> : true_type { };
|
---|
1379 |
|
---|
1380 | template<typename _Tp>
|
---|
1381 | static constexpr bool __not_in_place_tag
|
---|
1382 | = !__is_in_place_tag<__remove_cvref_t<_Tp>>::value;
|
---|
1383 |
|
---|
1384 | public:
|
---|
1385 | variant() = default;
|
---|
1386 | variant(const variant& __rhs) = default;
|
---|
1387 | variant(variant&&) = default;
|
---|
1388 | variant& operator=(const variant&) = default;
|
---|
1389 | variant& operator=(variant&&) = default;
|
---|
1390 | ~variant() = default;
|
---|
1391 |
|
---|
1392 | template<typename _Tp,
|
---|
1393 | typename = enable_if_t<sizeof...(_Types) != 0>,
|
---|
1394 | typename = enable_if_t<__not_in_place_tag<_Tp>>,
|
---|
1395 | typename _Tj = __accepted_type<_Tp&&>,
|
---|
1396 | typename = enable_if_t<__exactly_once<_Tj>
|
---|
1397 | && is_constructible_v<_Tj, _Tp>>>
|
---|
1398 | constexpr
|
---|
1399 | variant(_Tp&& __t)
|
---|
1400 | noexcept(is_nothrow_constructible_v<_Tj, _Tp>)
|
---|
1401 | : variant(in_place_index<__accepted_index<_Tp>>,
|
---|
1402 | std::forward<_Tp>(__t))
|
---|
1403 | { }
|
---|
1404 |
|
---|
1405 | template<typename _Tp, typename... _Args,
|
---|
1406 | typename = enable_if_t<__exactly_once<_Tp>
|
---|
1407 | && is_constructible_v<_Tp, _Args...>>>
|
---|
1408 | constexpr explicit
|
---|
1409 | variant(in_place_type_t<_Tp>, _Args&&... __args)
|
---|
1410 | : variant(in_place_index<__index_of<_Tp>>,
|
---|
1411 | std::forward<_Args>(__args)...)
|
---|
1412 | { }
|
---|
1413 |
|
---|
1414 | template<typename _Tp, typename _Up, typename... _Args,
|
---|
1415 | typename = enable_if_t<__exactly_once<_Tp>
|
---|
1416 | && is_constructible_v<_Tp,
|
---|
1417 | initializer_list<_Up>&, _Args...>>>
|
---|
1418 | constexpr explicit
|
---|
1419 | variant(in_place_type_t<_Tp>, initializer_list<_Up> __il,
|
---|
1420 | _Args&&... __args)
|
---|
1421 | : variant(in_place_index<__index_of<_Tp>>, __il,
|
---|
1422 | std::forward<_Args>(__args)...)
|
---|
1423 | { }
|
---|
1424 |
|
---|
1425 | template<size_t _Np, typename... _Args,
|
---|
1426 | typename _Tp = __to_type<_Np>,
|
---|
1427 | typename = enable_if_t<is_constructible_v<_Tp, _Args...>>>
|
---|
1428 | constexpr explicit
|
---|
1429 | variant(in_place_index_t<_Np>, _Args&&... __args)
|
---|
1430 | : _Base(in_place_index<_Np>, std::forward<_Args>(__args)...),
|
---|
1431 | _Default_ctor_enabler(_Enable_default_constructor_tag{})
|
---|
1432 | { }
|
---|
1433 |
|
---|
1434 | template<size_t _Np, typename _Up, typename... _Args,
|
---|
1435 | typename _Tp = __to_type<_Np>,
|
---|
1436 | typename = enable_if_t<is_constructible_v<_Tp,
|
---|
1437 | initializer_list<_Up>&,
|
---|
1438 | _Args...>>>
|
---|
1439 | constexpr explicit
|
---|
1440 | variant(in_place_index_t<_Np>, initializer_list<_Up> __il,
|
---|
1441 | _Args&&... __args)
|
---|
1442 | : _Base(in_place_index<_Np>, __il, std::forward<_Args>(__args)...),
|
---|
1443 | _Default_ctor_enabler(_Enable_default_constructor_tag{})
|
---|
1444 | { }
|
---|
1445 |
|
---|
1446 | template<typename _Tp>
|
---|
1447 | enable_if_t<__exactly_once<__accepted_type<_Tp&&>>
|
---|
1448 | && is_constructible_v<__accepted_type<_Tp&&>, _Tp>
|
---|
1449 | && is_assignable_v<__accepted_type<_Tp&&>&, _Tp>,
|
---|
1450 | variant&>
|
---|
1451 | operator=(_Tp&& __rhs)
|
---|
1452 | noexcept(is_nothrow_assignable_v<__accepted_type<_Tp&&>&, _Tp>
|
---|
1453 | && is_nothrow_constructible_v<__accepted_type<_Tp&&>, _Tp>)
|
---|
1454 | {
|
---|
1455 | constexpr auto __index = __accepted_index<_Tp>;
|
---|
1456 | if (index() == __index)
|
---|
1457 | std::get<__index>(*this) = std::forward<_Tp>(__rhs);
|
---|
1458 | else
|
---|
1459 | {
|
---|
1460 | using _Tj = __accepted_type<_Tp&&>;
|
---|
1461 | if constexpr (is_nothrow_constructible_v<_Tj, _Tp>
|
---|
1462 | || !is_nothrow_move_constructible_v<_Tj>)
|
---|
1463 | this->emplace<__index>(std::forward<_Tp>(__rhs));
|
---|
1464 | else
|
---|
1465 | operator=(variant(std::forward<_Tp>(__rhs)));
|
---|
1466 | }
|
---|
1467 | return *this;
|
---|
1468 | }
|
---|
1469 |
|
---|
1470 | template<typename _Tp, typename... _Args>
|
---|
1471 | enable_if_t<is_constructible_v<_Tp, _Args...> && __exactly_once<_Tp>,
|
---|
1472 | _Tp&>
|
---|
1473 | emplace(_Args&&... __args)
|
---|
1474 | {
|
---|
1475 | constexpr size_t __index = __index_of<_Tp>;
|
---|
1476 | return this->emplace<__index>(std::forward<_Args>(__args)...);
|
---|
1477 | }
|
---|
1478 |
|
---|
1479 | template<typename _Tp, typename _Up, typename... _Args>
|
---|
1480 | enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>
|
---|
1481 | && __exactly_once<_Tp>,
|
---|
1482 | _Tp&>
|
---|
1483 | emplace(initializer_list<_Up> __il, _Args&&... __args)
|
---|
1484 | {
|
---|
1485 | constexpr size_t __index = __index_of<_Tp>;
|
---|
1486 | return this->emplace<__index>(__il, std::forward<_Args>(__args)...);
|
---|
1487 | }
|
---|
1488 |
|
---|
1489 | template<size_t _Np, typename... _Args>
|
---|
1490 | enable_if_t<is_constructible_v<variant_alternative_t<_Np, variant>,
|
---|
1491 | _Args...>,
|
---|
1492 | variant_alternative_t<_Np, variant>&>
|
---|
1493 | emplace(_Args&&... __args)
|
---|
1494 | {
|
---|
1495 | static_assert(_Np < sizeof...(_Types),
|
---|
1496 | "The index must be in [0, number of alternatives)");
|
---|
1497 | using type = variant_alternative_t<_Np, variant>;
|
---|
1498 | // Provide the strong exception-safety guarantee when possible,
|
---|
1499 | // to avoid becoming valueless.
|
---|
1500 | if constexpr (is_nothrow_constructible_v<type, _Args...>)
|
---|
1501 | {
|
---|
1502 | this->_M_reset();
|
---|
1503 | __variant_construct_by_index<_Np>(*this,
|
---|
1504 | std::forward<_Args>(__args)...);
|
---|
1505 | }
|
---|
1506 | else if constexpr (is_scalar_v<type>)
|
---|
1507 | {
|
---|
1508 | // This might invoke a potentially-throwing conversion operator:
|
---|
1509 | const type __tmp(std::forward<_Args>(__args)...);
|
---|
1510 | // But these steps won't throw:
|
---|
1511 | this->_M_reset();
|
---|
1512 | __variant_construct_by_index<_Np>(*this, __tmp);
|
---|
1513 | }
|
---|
1514 | else if constexpr (__detail::__variant::_Never_valueless_alt<type>()
|
---|
1515 | && _Traits::_S_move_assign)
|
---|
1516 | {
|
---|
1517 | // This construction might throw:
|
---|
1518 | variant __tmp(in_place_index<_Np>,
|
---|
1519 | std::forward<_Args>(__args)...);
|
---|
1520 | // But _Never_valueless_alt<type> means this won't:
|
---|
1521 | *this = std::move(__tmp);
|
---|
1522 | }
|
---|
1523 | else
|
---|
1524 | {
|
---|
1525 | // This case only provides the basic exception-safety guarantee,
|
---|
1526 | // i.e. the variant can become valueless.
|
---|
1527 | this->_M_reset();
|
---|
1528 | __try
|
---|
1529 | {
|
---|
1530 | __variant_construct_by_index<_Np>(*this,
|
---|
1531 | std::forward<_Args>(__args)...);
|
---|
1532 | }
|
---|
1533 | __catch (...)
|
---|
1534 | {
|
---|
1535 | using __index_type = decltype(this->_M_index);
|
---|
1536 | this->_M_index = static_cast<__index_type>(variant_npos);
|
---|
1537 | __throw_exception_again;
|
---|
1538 | }
|
---|
1539 | }
|
---|
1540 | return std::get<_Np>(*this);
|
---|
1541 | }
|
---|
1542 |
|
---|
1543 | template<size_t _Np, typename _Up, typename... _Args>
|
---|
1544 | enable_if_t<is_constructible_v<variant_alternative_t<_Np, variant>,
|
---|
1545 | initializer_list<_Up>&, _Args...>,
|
---|
1546 | variant_alternative_t<_Np, variant>&>
|
---|
1547 | emplace(initializer_list<_Up> __il, _Args&&... __args)
|
---|
1548 | {
|
---|
1549 | static_assert(_Np < sizeof...(_Types),
|
---|
1550 | "The index must be in [0, number of alternatives)");
|
---|
1551 | using type = variant_alternative_t<_Np, variant>;
|
---|
1552 | // Provide the strong exception-safety guarantee when possible,
|
---|
1553 | // to avoid becoming valueless.
|
---|
1554 | if constexpr (is_nothrow_constructible_v<type,
|
---|
1555 | initializer_list<_Up>&,
|
---|
1556 | _Args...>)
|
---|
1557 | {
|
---|
1558 | this->_M_reset();
|
---|
1559 | __variant_construct_by_index<_Np>(*this, __il,
|
---|
1560 | std::forward<_Args>(__args)...);
|
---|
1561 | }
|
---|
1562 | else if constexpr (__detail::__variant::_Never_valueless_alt<type>()
|
---|
1563 | && _Traits::_S_move_assign)
|
---|
1564 | {
|
---|
1565 | // This construction might throw:
|
---|
1566 | variant __tmp(in_place_index<_Np>, __il,
|
---|
1567 | std::forward<_Args>(__args)...);
|
---|
1568 | // But _Never_valueless_alt<type> means this won't:
|
---|
1569 | *this = std::move(__tmp);
|
---|
1570 | }
|
---|
1571 | else
|
---|
1572 | {
|
---|
1573 | // This case only provides the basic exception-safety guarantee,
|
---|
1574 | // i.e. the variant can become valueless.
|
---|
1575 | this->_M_reset();
|
---|
1576 | __try
|
---|
1577 | {
|
---|
1578 | __variant_construct_by_index<_Np>(*this, __il,
|
---|
1579 | std::forward<_Args>(__args)...);
|
---|
1580 | }
|
---|
1581 | __catch (...)
|
---|
1582 | {
|
---|
1583 | using __index_type = decltype(this->_M_index);
|
---|
1584 | this->_M_index = static_cast<__index_type>(variant_npos);
|
---|
1585 | __throw_exception_again;
|
---|
1586 | }
|
---|
1587 | }
|
---|
1588 | return std::get<_Np>(*this);
|
---|
1589 | }
|
---|
1590 |
|
---|
1591 | constexpr bool valueless_by_exception() const noexcept
|
---|
1592 | { return !this->_M_valid(); }
|
---|
1593 |
|
---|
1594 | constexpr size_t index() const noexcept
|
---|
1595 | {
|
---|
1596 | using __index_type = typename _Base::__index_type;
|
---|
1597 | if constexpr (__detail::__variant::__never_valueless<_Types...>())
|
---|
1598 | return this->_M_index;
|
---|
1599 | else if constexpr (sizeof...(_Types) <= __index_type(-1) / 2)
|
---|
1600 | return make_signed_t<__index_type>(this->_M_index);
|
---|
1601 | else
|
---|
1602 | return size_t(__index_type(this->_M_index + 1)) - 1;
|
---|
1603 | }
|
---|
1604 |
|
---|
1605 | void
|
---|
1606 | swap(variant& __rhs)
|
---|
1607 | noexcept((__is_nothrow_swappable<_Types>::value && ...)
|
---|
1608 | && is_nothrow_move_constructible_v<variant>)
|
---|
1609 | {
|
---|
1610 | __detail::__variant::__raw_idx_visit(
|
---|
1611 | [this, &__rhs](auto&& __rhs_mem, auto __rhs_index) mutable
|
---|
1612 | {
|
---|
1613 | if constexpr (__rhs_index != variant_npos)
|
---|
1614 | {
|
---|
1615 | if (this->index() == __rhs_index)
|
---|
1616 | {
|
---|
1617 | auto& __this_mem =
|
---|
1618 | std::get<__rhs_index>(*this);
|
---|
1619 | using std::swap;
|
---|
1620 | swap(__this_mem, __rhs_mem);
|
---|
1621 | }
|
---|
1622 | else
|
---|
1623 | {
|
---|
1624 | if (!this->valueless_by_exception()) [[__likely__]]
|
---|
1625 | {
|
---|
1626 | auto __tmp(std::move(__rhs_mem));
|
---|
1627 | __rhs = std::move(*this);
|
---|
1628 | this->_M_destructive_move(__rhs_index,
|
---|
1629 | std::move(__tmp));
|
---|
1630 | }
|
---|
1631 | else
|
---|
1632 | {
|
---|
1633 | this->_M_destructive_move(__rhs_index,
|
---|
1634 | std::move(__rhs_mem));
|
---|
1635 | __rhs._M_reset();
|
---|
1636 | }
|
---|
1637 | }
|
---|
1638 | }
|
---|
1639 | else
|
---|
1640 | {
|
---|
1641 | if (!this->valueless_by_exception()) [[__likely__]]
|
---|
1642 | {
|
---|
1643 | __rhs = std::move(*this);
|
---|
1644 | this->_M_reset();
|
---|
1645 | }
|
---|
1646 | }
|
---|
1647 | }, __rhs);
|
---|
1648 | }
|
---|
1649 |
|
---|
1650 | private:
|
---|
1651 |
|
---|
1652 | #if defined(__clang__) && __clang_major__ <= 7
|
---|
1653 | public:
|
---|
1654 | using _Base::_M_u; // See https://bugs.llvm.org/show_bug.cgi?id=31852
|
---|
1655 | private:
|
---|
1656 | #endif
|
---|
1657 |
|
---|
1658 | template<size_t _Np, typename _Vp>
|
---|
1659 | friend constexpr decltype(auto)
|
---|
1660 | __detail::__variant::__get(_Vp&& __v) noexcept;
|
---|
1661 |
|
---|
1662 | template<typename _Vp>
|
---|
1663 | friend void*
|
---|
1664 | __detail::__variant::__get_storage(_Vp&& __v) noexcept;
|
---|
1665 |
|
---|
1666 | #define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP) \
|
---|
1667 | template<typename... _Tp> \
|
---|
1668 | friend constexpr bool \
|
---|
1669 | operator __OP(const variant<_Tp...>& __lhs, \
|
---|
1670 | const variant<_Tp...>& __rhs);
|
---|
1671 |
|
---|
1672 | _VARIANT_RELATION_FUNCTION_TEMPLATE(<)
|
---|
1673 | _VARIANT_RELATION_FUNCTION_TEMPLATE(<=)
|
---|
1674 | _VARIANT_RELATION_FUNCTION_TEMPLATE(==)
|
---|
1675 | _VARIANT_RELATION_FUNCTION_TEMPLATE(!=)
|
---|
1676 | _VARIANT_RELATION_FUNCTION_TEMPLATE(>=)
|
---|
1677 | _VARIANT_RELATION_FUNCTION_TEMPLATE(>)
|
---|
1678 |
|
---|
1679 | #undef _VARIANT_RELATION_FUNCTION_TEMPLATE
|
---|
1680 | };
|
---|
1681 |
|
---|
1682 | template<size_t _Np, typename... _Types>
|
---|
1683 | constexpr variant_alternative_t<_Np, variant<_Types...>>&
|
---|
1684 | get(variant<_Types...>& __v)
|
---|
1685 | {
|
---|
1686 | static_assert(_Np < sizeof...(_Types),
|
---|
1687 | "The index must be in [0, number of alternatives)");
|
---|
1688 | if (__v.index() != _Np)
|
---|
1689 | __throw_bad_variant_access(__v.valueless_by_exception());
|
---|
1690 | return __detail::__variant::__get<_Np>(__v);
|
---|
1691 | }
|
---|
1692 |
|
---|
1693 | template<size_t _Np, typename... _Types>
|
---|
1694 | constexpr variant_alternative_t<_Np, variant<_Types...>>&&
|
---|
1695 | get(variant<_Types...>&& __v)
|
---|
1696 | {
|
---|
1697 | static_assert(_Np < sizeof...(_Types),
|
---|
1698 | "The index must be in [0, number of alternatives)");
|
---|
1699 | if (__v.index() != _Np)
|
---|
1700 | __throw_bad_variant_access(__v.valueless_by_exception());
|
---|
1701 | return __detail::__variant::__get<_Np>(std::move(__v));
|
---|
1702 | }
|
---|
1703 |
|
---|
1704 | template<size_t _Np, typename... _Types>
|
---|
1705 | constexpr const variant_alternative_t<_Np, variant<_Types...>>&
|
---|
1706 | get(const variant<_Types...>& __v)
|
---|
1707 | {
|
---|
1708 | static_assert(_Np < sizeof...(_Types),
|
---|
1709 | "The index must be in [0, number of alternatives)");
|
---|
1710 | if (__v.index() != _Np)
|
---|
1711 | __throw_bad_variant_access(__v.valueless_by_exception());
|
---|
1712 | return __detail::__variant::__get<_Np>(__v);
|
---|
1713 | }
|
---|
1714 |
|
---|
1715 | template<size_t _Np, typename... _Types>
|
---|
1716 | constexpr const variant_alternative_t<_Np, variant<_Types...>>&&
|
---|
1717 | get(const variant<_Types...>&& __v)
|
---|
1718 | {
|
---|
1719 | static_assert(_Np < sizeof...(_Types),
|
---|
1720 | "The index must be in [0, number of alternatives)");
|
---|
1721 | if (__v.index() != _Np)
|
---|
1722 | __throw_bad_variant_access(__v.valueless_by_exception());
|
---|
1723 | return __detail::__variant::__get<_Np>(std::move(__v));
|
---|
1724 | }
|
---|
1725 |
|
---|
1726 | template<typename _Result_type, typename _Visitor, typename... _Variants>
|
---|
1727 | constexpr decltype(auto)
|
---|
1728 | __do_visit(_Visitor&& __visitor, _Variants&&... __variants)
|
---|
1729 | {
|
---|
1730 | constexpr auto& __vtable = __detail::__variant::__gen_vtable<
|
---|
1731 | _Result_type, _Visitor&&, _Variants&&...>::_S_vtable;
|
---|
1732 |
|
---|
1733 | auto __func_ptr = __vtable._M_access(__variants.index()...);
|
---|
1734 | return (*__func_ptr)(std::forward<_Visitor>(__visitor),
|
---|
1735 | std::forward<_Variants>(__variants)...);
|
---|
1736 | }
|
---|
1737 |
|
---|
1738 | template<typename _Visitor, typename... _Variants>
|
---|
1739 | constexpr __detail::__variant::__visit_result_t<_Visitor, _Variants...>
|
---|
1740 | visit(_Visitor&& __visitor, _Variants&&... __variants)
|
---|
1741 | {
|
---|
1742 | if ((__variants.valueless_by_exception() || ...))
|
---|
1743 | __throw_bad_variant_access("std::visit: variant is valueless");
|
---|
1744 |
|
---|
1745 | using _Result_type
|
---|
1746 | = __detail::__variant::__visit_result_t<_Visitor, _Variants...>;
|
---|
1747 |
|
---|
1748 | using _Tag = __detail::__variant::__deduce_visit_result<_Result_type>;
|
---|
1749 |
|
---|
1750 | if constexpr (sizeof...(_Variants) == 1)
|
---|
1751 | {
|
---|
1752 | constexpr bool __visit_rettypes_match = __detail::__variant::
|
---|
1753 | __check_visitor_results<_Visitor, _Variants...>(
|
---|
1754 | std::make_index_sequence<
|
---|
1755 | std::variant_size<remove_reference_t<_Variants>...>::value>());
|
---|
1756 | if constexpr (!__visit_rettypes_match)
|
---|
1757 | {
|
---|
1758 | static_assert(__visit_rettypes_match,
|
---|
1759 | "std::visit requires the visitor to have the same "
|
---|
1760 | "return type for all alternatives of a variant");
|
---|
1761 | return;
|
---|
1762 | }
|
---|
1763 | else
|
---|
1764 | return std::__do_visit<_Tag>(
|
---|
1765 | std::forward<_Visitor>(__visitor),
|
---|
1766 | std::forward<_Variants>(__variants)...);
|
---|
1767 | }
|
---|
1768 | else
|
---|
1769 | return std::__do_visit<_Tag>(
|
---|
1770 | std::forward<_Visitor>(__visitor),
|
---|
1771 | std::forward<_Variants>(__variants)...);
|
---|
1772 | }
|
---|
1773 |
|
---|
1774 | #if __cplusplus > 201703L
|
---|
1775 | template<typename _Res, typename _Visitor, typename... _Variants>
|
---|
1776 | constexpr _Res
|
---|
1777 | visit(_Visitor&& __visitor, _Variants&&... __variants)
|
---|
1778 | {
|
---|
1779 | if ((__variants.valueless_by_exception() || ...))
|
---|
1780 | __throw_bad_variant_access("std::visit<R>: variant is valueless");
|
---|
1781 |
|
---|
1782 | return std::__do_visit<_Res>(std::forward<_Visitor>(__visitor),
|
---|
1783 | std::forward<_Variants>(__variants)...);
|
---|
1784 | }
|
---|
1785 | #endif
|
---|
1786 |
|
---|
1787 | template<bool, typename... _Types>
|
---|
1788 | struct __variant_hash_call_base_impl
|
---|
1789 | {
|
---|
1790 | size_t
|
---|
1791 | operator()(const variant<_Types...>& __t) const
|
---|
1792 | noexcept((is_nothrow_invocable_v<hash<decay_t<_Types>>, _Types> && ...))
|
---|
1793 | {
|
---|
1794 | size_t __ret;
|
---|
1795 | __detail::__variant::__raw_visit(
|
---|
1796 | [&__t, &__ret](auto&& __t_mem) mutable
|
---|
1797 | {
|
---|
1798 | using _Type = __remove_cvref_t<decltype(__t_mem)>;
|
---|
1799 | if constexpr (!is_same_v<_Type,
|
---|
1800 | __detail::__variant::__variant_cookie>)
|
---|
1801 | __ret = std::hash<size_t>{}(__t.index())
|
---|
1802 | + std::hash<_Type>{}(__t_mem);
|
---|
1803 | else
|
---|
1804 | __ret = std::hash<size_t>{}(__t.index());
|
---|
1805 | }, __t);
|
---|
1806 | return __ret;
|
---|
1807 | }
|
---|
1808 | };
|
---|
1809 |
|
---|
1810 | template<typename... _Types>
|
---|
1811 | struct __variant_hash_call_base_impl<false, _Types...> {};
|
---|
1812 |
|
---|
1813 | template<typename... _Types>
|
---|
1814 | using __variant_hash_call_base =
|
---|
1815 | __variant_hash_call_base_impl<(__poison_hash<remove_const_t<_Types>>::
|
---|
1816 | __enable_hash_call &&...), _Types...>;
|
---|
1817 |
|
---|
1818 | template<typename... _Types>
|
---|
1819 | struct hash<variant<_Types...>>
|
---|
1820 | : private __detail::__variant::_Variant_hash_base<
|
---|
1821 | variant<_Types...>, std::index_sequence_for<_Types...>>,
|
---|
1822 | public __variant_hash_call_base<_Types...>
|
---|
1823 | {
|
---|
1824 | using result_type [[__deprecated__]] = size_t;
|
---|
1825 | using argument_type [[__deprecated__]] = variant<_Types...>;
|
---|
1826 | };
|
---|
1827 |
|
---|
1828 | template<>
|
---|
1829 | struct hash<monostate>
|
---|
1830 | {
|
---|
1831 | using result_type [[__deprecated__]] = size_t;
|
---|
1832 | using argument_type [[__deprecated__]] = monostate;
|
---|
1833 |
|
---|
1834 | size_t
|
---|
1835 | operator()(const monostate&) const noexcept
|
---|
1836 | {
|
---|
1837 | constexpr size_t __magic_monostate_hash = -7777;
|
---|
1838 | return __magic_monostate_hash;
|
---|
1839 | }
|
---|
1840 | };
|
---|
1841 |
|
---|
1842 | template<typename... _Types>
|
---|
1843 | struct __is_fast_hash<hash<variant<_Types...>>>
|
---|
1844 | : bool_constant<(__is_fast_hash<_Types>::value && ...)>
|
---|
1845 | { };
|
---|
1846 |
|
---|
1847 | _GLIBCXX_END_NAMESPACE_VERSION
|
---|
1848 | } // namespace std
|
---|
1849 |
|
---|
1850 | #endif // C++17
|
---|
1851 |
|
---|
1852 | #endif // _GLIBCXX_VARIANT
|
---|