1// <variant> -*- C++ -*- 2 3// Copyright (C) 2016-2018 Free Software Foundation, Inc. 4// 5// This file is part of the GNU ISO C++ Library. This library is free 6// software; you can redistribute it and/or modify it under the 7// terms of the GNU General Public License as published by the 8// Free Software Foundation; either version 3, or (at your option) 9// any later version. 10 11// This library is distributed in the hope that it will be useful, 12// but WITHOUT ANY WARRANTY; without even the implied warranty of 13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14// GNU General Public License for more details. 15 16// Under Section 7 of GPL version 3, you are granted additional 17// permissions described in the GCC Runtime Library Exception, version 18// 3.1, as published by the Free Software Foundation. 19 20// You should have received a copy of the GNU General Public License and 21// a copy of the GCC Runtime Library Exception along with this program; 22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23// <http://www.gnu.org/licenses/>. 24 25/** @file variant 26 * This is the <variant> C++ Library header. 27 */ 28 29#ifndef _GLIBCXX_VARIANT 30#define _GLIBCXX_VARIANT 1 31 32#pragma GCC system_header 33 34#if __cplusplus >= 201703L 35 36#include <type_traits> 37#include <utility> 38#include <bits/enable_special_members.h> 39#include <bits/functexcept.h> 40#include <bits/move.h> 41#include <bits/functional_hash.h> 42#include <bits/invoke.h> 43#include <ext/aligned_buffer.h> 44#include <bits/parse_numbers.h> 45#include <bits/stl_iterator_base_types.h> 46#include <bits/stl_iterator_base_funcs.h> 47#include <bits/stl_construct.h> 48 49namespace std _GLIBCXX_VISIBILITY(default) 50{ 51_GLIBCXX_BEGIN_NAMESPACE_VERSION 52 53namespace __detail 54{ 55namespace __variant 56{ 57 template<size_t _Np, typename... _Types> 58 struct _Nth_type; 59 60 template<size_t _Np, typename _First, typename... _Rest> 61 struct _Nth_type<_Np, _First, _Rest...> 62 : _Nth_type<_Np-1, _Rest...> { }; 63 64 template<typename _First, typename... _Rest> 65 struct _Nth_type<0, _First, _Rest...> 66 { using type = _First; }; 67 68} // namespace __variant 69} // namespace __detail 70 71#define __cpp_lib_variant 201603 72 73 template<typename... _Types> class tuple; 74 template<typename... _Types> class variant; 75 template <typename> struct hash; 76 77 template<typename _Variant> 78 struct variant_size; 79 80 template<typename _Variant> 81 struct variant_size<const _Variant> : variant_size<_Variant> {}; 82 83 template<typename _Variant> 84 struct variant_size<volatile _Variant> : variant_size<_Variant> {}; 85 86 template<typename _Variant> 87 struct variant_size<const volatile _Variant> : variant_size<_Variant> {}; 88 89 template<typename... _Types> 90 struct variant_size<variant<_Types...>> 91 : std::integral_constant<size_t, sizeof...(_Types)> {}; 92 93 template<typename _Variant> 94 inline constexpr size_t variant_size_v = variant_size<_Variant>::value; 95 96 template<size_t _Np, typename _Variant> 97 struct variant_alternative; 98 99 template<size_t _Np, typename _First, typename... _Rest> 100 struct variant_alternative<_Np, variant<_First, _Rest...>> 101 : variant_alternative<_Np-1, variant<_Rest...>> {}; 102 103 template<typename _First, typename... _Rest> 104 struct variant_alternative<0, variant<_First, _Rest...>> 105 { using type = _First; }; 106 107 template<size_t _Np, typename _Variant> 108 using variant_alternative_t = 109 typename variant_alternative<_Np, _Variant>::type; 110 111 template<size_t _Np, typename _Variant> 112 struct variant_alternative<_Np, const _Variant> 113 { using type = add_const_t<variant_alternative_t<_Np, _Variant>>; }; 114 115 template<size_t _Np, typename _Variant> 116 struct variant_alternative<_Np, volatile _Variant> 117 { using type = add_volatile_t<variant_alternative_t<_Np, _Variant>>; }; 118 119 template<size_t _Np, typename _Variant> 120 struct variant_alternative<_Np, const volatile _Variant> 121 { using type = add_cv_t<variant_alternative_t<_Np, _Variant>>; }; 122 123 inline constexpr size_t variant_npos = -1; 124 125 template<size_t _Np, typename... _Types> 126 constexpr variant_alternative_t<_Np, variant<_Types...>>& 127 get(variant<_Types...>&); 128 129 template<size_t _Np, typename... _Types> 130 constexpr variant_alternative_t<_Np, variant<_Types...>>&& 131 get(variant<_Types...>&&); 132 133 template<size_t _Np, typename... _Types> 134 constexpr variant_alternative_t<_Np, variant<_Types...>> const& 135 get(const variant<_Types...>&); 136 137 template<size_t _Np, typename... _Types> 138 constexpr variant_alternative_t<_Np, variant<_Types...>> const&& 139 get(const variant<_Types...>&&); 140 141namespace __detail 142{ 143namespace __variant 144{ 145 // Returns the first apparence of _Tp in _Types. 146 // Returns sizeof...(_Types) if _Tp is not in _Types. 147 template<typename _Tp, typename... _Types> 148 struct __index_of : std::integral_constant<size_t, 0> {}; 149 150 template<typename _Tp, typename... _Types> 151 inline constexpr size_t __index_of_v = __index_of<_Tp, _Types...>::value; 152 153 template<typename _Tp, typename _First, typename... _Rest> 154 struct __index_of<_Tp, _First, _Rest...> : 155 std::integral_constant<size_t, is_same_v<_Tp, _First> 156 ? 0 : __index_of_v<_Tp, _Rest...> + 1> {}; 157 158 // _Uninitialized<T> is guaranteed to be a literal type, even if T is not. 159 // We have to do this, because [basic.types]p10.5.3 (n4606) is not implemented 160 // yet. When it's implemented, _Uninitialized<T> can be changed to the alias 161 // to T, therefore equivalent to being removed entirely. 162 // 163 // Another reason we may not want to remove _Uninitialzied<T> may be that, we 164 // want _Uninitialized<T> to be trivially destructible, no matter whether T 165 // is; but we will see. 166 template<typename _Type, bool = std::is_literal_type_v<_Type>> 167 struct _Uninitialized; 168 169 template<typename _Type> 170 struct _Uninitialized<_Type, true> 171 { 172 template<typename... _Args> 173 constexpr _Uninitialized(in_place_index_t<0>, _Args&&... __args) 174 : _M_storage(std::forward<_Args>(__args)...) 175 { } 176 177 constexpr const _Type& _M_get() const & 178 { return _M_storage; } 179 180 constexpr _Type& _M_get() & 181 { return _M_storage; } 182 183 constexpr const _Type&& _M_get() const && 184 { return std::move(_M_storage); } 185 186 constexpr _Type&& _M_get() && 187 { return std::move(_M_storage); } 188 189 _Type _M_storage; 190 }; 191 192 template<typename _Type> 193 struct _Uninitialized<_Type, false> 194 { 195 template<typename... _Args> 196 constexpr _Uninitialized(in_place_index_t<0>, _Args&&... __args) 197 { ::new (&_M_storage) _Type(std::forward<_Args>(__args)...); } 198 199 const _Type& _M_get() const & 200 { return *_M_storage._M_ptr(); } 201 202 _Type& _M_get() & 203 { return *_M_storage._M_ptr(); } 204 205 const _Type&& _M_get() const && 206 { return std::move(*_M_storage._M_ptr()); } 207 208 _Type&& _M_get() && 209 { return std::move(*_M_storage._M_ptr()); } 210 211 __gnu_cxx::__aligned_membuf<_Type> _M_storage; 212 }; 213 214 template<typename _Ref> 215 _Ref __ref_cast(void* __ptr) 216 { 217 return static_cast<_Ref>(*static_cast<remove_reference_t<_Ref>*>(__ptr)); 218 } 219 220 template<typename _Union> 221 constexpr decltype(auto) __get(in_place_index_t<0>, _Union&& __u) 222 { return std::forward<_Union>(__u)._M_first._M_get(); } 223 224 template<size_t _Np, typename _Union> 225 constexpr decltype(auto) __get(in_place_index_t<_Np>, _Union&& __u) 226 { 227 return __variant::__get(in_place_index<_Np-1>, 228 std::forward<_Union>(__u)._M_rest); 229 } 230 231 // Returns the typed storage for __v. 232 template<size_t _Np, typename _Variant> 233 constexpr decltype(auto) __get(_Variant&& __v) 234 { 235 return __variant::__get(std::in_place_index<_Np>, 236 std::forward<_Variant>(__v)._M_u); 237 } 238 239 // Various functions as "vtable" entries, where those vtables are used by 240 // polymorphic operations. 241 template<typename _Lhs, typename _Rhs> 242 void 243 __erased_ctor(void* __lhs, void* __rhs) 244 { 245 using _Type = remove_reference_t<_Lhs>; 246 ::new (__lhs) _Type(__variant::__ref_cast<_Rhs>(__rhs)); 247 } 248 249 template<typename _Variant, size_t _Np> 250 void 251 __erased_dtor(_Variant&& __v) 252 { std::_Destroy(std::__addressof(__variant::__get<_Np>(__v))); } 253 254 template<typename _Lhs, typename _Rhs> 255 void 256 __erased_assign(void* __lhs, void* __rhs) 257 { 258 __variant::__ref_cast<_Lhs>(__lhs) = __variant::__ref_cast<_Rhs>(__rhs); 259 } 260 261 template<typename _Lhs, typename _Rhs> 262 void 263 __erased_swap(void* __lhs, void* __rhs) 264 { 265 using std::swap; 266 swap(__variant::__ref_cast<_Lhs>(__lhs), 267 __variant::__ref_cast<_Rhs>(__rhs)); 268 } 269 270#define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP, __NAME) \ 271 template<typename _Variant, size_t _Np> \ 272 constexpr bool \ 273 __erased_##__NAME(const _Variant& __lhs, const _Variant& __rhs) \ 274 { \ 275 return __variant::__get<_Np>(std::forward<_Variant>(__lhs)) \ 276 __OP __variant::__get<_Np>(std::forward<_Variant>(__rhs)); \ 277 } 278 279 _VARIANT_RELATION_FUNCTION_TEMPLATE(<, less) 280 _VARIANT_RELATION_FUNCTION_TEMPLATE(<=, less_equal) 281 _VARIANT_RELATION_FUNCTION_TEMPLATE(==, equal) 282 _VARIANT_RELATION_FUNCTION_TEMPLATE(!=, not_equal) 283 _VARIANT_RELATION_FUNCTION_TEMPLATE(>=, greater_equal) 284 _VARIANT_RELATION_FUNCTION_TEMPLATE(>, greater) 285 286#undef _VARIANT_RELATION_FUNCTION_TEMPLATE 287 288 template<typename _Tp> 289 size_t 290 __erased_hash(void* __t) 291 { 292 return std::hash<remove_cv_t<remove_reference_t<_Tp>>>{}( 293 __variant::__ref_cast<_Tp>(__t)); 294 } 295 296 template<typename... _Types> 297 struct _Traits 298 { 299 static constexpr bool _S_default_ctor = 300 is_default_constructible_v<typename _Nth_type<0, _Types...>::type>; 301 static constexpr bool _S_copy_ctor = 302 (is_copy_constructible_v<_Types> && ...); 303 static constexpr bool _S_move_ctor = 304 (is_move_constructible_v<_Types> && ...); 305 static constexpr bool _S_copy_assign = 306 _S_copy_ctor && _S_move_ctor 307 && (is_copy_assignable_v<_Types> && ...); 308 static constexpr bool _S_move_assign = 309 _S_move_ctor 310 && (is_move_assignable_v<_Types> && ...); 311 312 static constexpr bool _S_trivial_dtor = 313 (is_trivially_destructible_v<_Types> && ...); 314 static constexpr bool _S_trivial_copy_ctor = 315 (is_trivially_copy_constructible_v<_Types> && ...); 316 static constexpr bool _S_trivial_move_ctor = 317 (is_trivially_move_constructible_v<_Types> && ...); 318 static constexpr bool _S_trivial_copy_assign = 319 _S_trivial_dtor && (is_trivially_copy_assignable_v<_Types> && ...); 320 static constexpr bool _S_trivial_move_assign = 321 _S_trivial_dtor && (is_trivially_move_assignable_v<_Types> && ...); 322 323 // The following nothrow traits are for non-trivial SMFs. Trivial SMFs 324 // are always nothrow. 325 static constexpr bool _S_nothrow_default_ctor = 326 is_nothrow_default_constructible_v< 327 typename _Nth_type<0, _Types...>::type>; 328 static constexpr bool _S_nothrow_copy_ctor = false; 329 static constexpr bool _S_nothrow_move_ctor = 330 (is_nothrow_move_constructible_v<_Types> && ...); 331 static constexpr bool _S_nothrow_copy_assign = false; 332 static constexpr bool _S_nothrow_move_assign = 333 _S_nothrow_move_ctor && (is_nothrow_move_assignable_v<_Types> && ...); 334 }; 335 336 // Defines members and ctors. 337 template<typename... _Types> 338 union _Variadic_union { }; 339 340 template<typename _First, typename... _Rest> 341 union _Variadic_union<_First, _Rest...> 342 { 343 constexpr _Variadic_union() : _M_rest() { } 344 345 template<typename... _Args> 346 constexpr _Variadic_union(in_place_index_t<0>, _Args&&... __args) 347 : _M_first(in_place_index<0>, std::forward<_Args>(__args)...) 348 { } 349 350 template<size_t _Np, typename... _Args> 351 constexpr _Variadic_union(in_place_index_t<_Np>, _Args&&... __args) 352 : _M_rest(in_place_index<_Np-1>, std::forward<_Args>(__args)...) 353 { } 354 355 _Uninitialized<_First> _M_first; 356 _Variadic_union<_Rest...> _M_rest; 357 }; 358 359 // Defines index and the dtor, possibly trivial. 360 template<bool __trivially_destructible, typename... _Types> 361 struct _Variant_storage; 362 363 template <typename... _Types> 364 using __select_index = 365 typename __select_int::_Select_int_base<sizeof...(_Types) + 1, 366 unsigned char, 367 unsigned short>::type::value_type; 368 369 template<typename... _Types> 370 struct _Variant_storage<false, _Types...> 371 { 372 template<size_t... __indices> 373 static constexpr void (*_S_vtable[])(const _Variant_storage&) = 374 { &__erased_dtor<const _Variant_storage&, __indices>... }; 375 376 constexpr _Variant_storage() : _M_index(variant_npos) { } 377 378 template<size_t _Np, typename... _Args> 379 constexpr _Variant_storage(in_place_index_t<_Np>, _Args&&... __args) 380 : _M_u(in_place_index<_Np>, std::forward<_Args>(__args)...), 381 _M_index(_Np) 382 { } 383 384 template<size_t... __indices> 385 constexpr void _M_reset_impl(std::index_sequence<__indices...>) 386 { 387 if (_M_index != __index_type(variant_npos)) 388 _S_vtable<__indices...>[_M_index](*this); 389 } 390 391 void _M_reset() 392 { 393 _M_reset_impl(std::index_sequence_for<_Types...>{}); 394 _M_index = variant_npos; 395 } 396 397 ~_Variant_storage() 398 { _M_reset(); } 399 400 void* 401 _M_storage() const 402 { 403 return const_cast<void*>(static_cast<const void*>( 404 std::addressof(_M_u))); 405 } 406 407 constexpr bool 408 _M_valid() const noexcept 409 { 410 return this->_M_index != __index_type(variant_npos); 411 } 412 413 _Variadic_union<_Types...> _M_u; 414 using __index_type = __select_index<_Types...>; 415 __index_type _M_index; 416 }; 417 418 template<typename... _Types> 419 struct _Variant_storage<true, _Types...> 420 { 421 constexpr _Variant_storage() : _M_index(variant_npos) { } 422 423 template<size_t _Np, typename... _Args> 424 constexpr _Variant_storage(in_place_index_t<_Np>, _Args&&... __args) 425 : _M_u(in_place_index<_Np>, std::forward<_Args>(__args)...), 426 _M_index(_Np) 427 { } 428 429 void _M_reset() 430 { _M_index = variant_npos; } 431 432 void* 433 _M_storage() const 434 { 435 return const_cast<void*>(static_cast<const void*>( 436 std::addressof(_M_u))); 437 } 438 439 constexpr bool 440 _M_valid() const noexcept 441 { 442 return this->_M_index != __index_type(variant_npos); 443 } 444 445 _Variadic_union<_Types...> _M_u; 446 using __index_type = __select_index<_Types...>; 447 __index_type _M_index; 448 }; 449 450 template<typename... _Types> 451 using _Variant_storage_alias = 452 _Variant_storage<_Traits<_Types...>::_S_trivial_dtor, _Types...>; 453 454 // The following are (Copy|Move) (ctor|assign) layers for forwarding 455 // triviality and handling non-trivial SMF behaviors. 456 457 template<bool, typename... _Types> 458 struct _Copy_ctor_base : _Variant_storage_alias<_Types...> 459 { 460 using _Base = _Variant_storage_alias<_Types...>; 461 using _Base::_Base; 462 463 _Copy_ctor_base(const _Copy_ctor_base& __rhs) 464 noexcept(_Traits<_Types...>::_S_nothrow_copy_ctor) 465 { 466 if (__rhs._M_valid()) 467 { 468 static constexpr void (*_S_vtable[])(void*, void*) = 469 { &__erased_ctor<_Types&, const _Types&>... }; 470 _S_vtable[__rhs._M_index](this->_M_storage(), __rhs._M_storage()); 471 this->_M_index = __rhs._M_index; 472 } 473 } 474 475 _Copy_ctor_base(_Copy_ctor_base&&) = default; 476 _Copy_ctor_base& operator=(const _Copy_ctor_base&) = default; 477 _Copy_ctor_base& operator=(_Copy_ctor_base&&) = default; 478 }; 479 480 template<typename... _Types> 481 struct _Copy_ctor_base<true, _Types...> : _Variant_storage_alias<_Types...> 482 { 483 using _Base = _Variant_storage_alias<_Types...>; 484 using _Base::_Base; 485 }; 486 487 template<typename... _Types> 488 using _Copy_ctor_alias = 489 _Copy_ctor_base<_Traits<_Types...>::_S_trivial_copy_ctor, _Types...>; 490 491 template<bool, typename... _Types> 492 struct _Move_ctor_base : _Copy_ctor_alias<_Types...> 493 { 494 using _Base = _Copy_ctor_alias<_Types...>; 495 using _Base::_Base; 496 497 _Move_ctor_base(_Move_ctor_base&& __rhs) 498 noexcept(_Traits<_Types...>::_S_nothrow_move_ctor) 499 { 500 if (__rhs._M_valid()) 501 { 502 static constexpr void (*_S_vtable[])(void*, void*) = 503 { &__erased_ctor<_Types&, _Types&&>... }; 504 _S_vtable[__rhs._M_index](this->_M_storage(), __rhs._M_storage()); 505 this->_M_index = __rhs._M_index; 506 } 507 } 508 509 void _M_destructive_move(_Move_ctor_base&& __rhs) 510 { 511 this->~_Move_ctor_base(); 512 __try 513 { 514 ::new (this) _Move_ctor_base(std::move(__rhs)); 515 } 516 __catch (...) 517 { 518 this->_M_index = variant_npos; 519 __throw_exception_again; 520 } 521 } 522 523 _Move_ctor_base(const _Move_ctor_base&) = default; 524 _Move_ctor_base& operator=(const _Move_ctor_base&) = default; 525 _Move_ctor_base& operator=(_Move_ctor_base&&) = default; 526 }; 527 528 template<typename... _Types> 529 struct _Move_ctor_base<true, _Types...> : _Copy_ctor_alias<_Types...> 530 { 531 using _Base = _Copy_ctor_alias<_Types...>; 532 using _Base::_Base; 533 534 void _M_destructive_move(_Move_ctor_base&& __rhs) 535 { 536 this->~_Move_ctor_base(); 537 ::new (this) _Move_ctor_base(std::move(__rhs)); 538 } 539 }; 540 541 template<typename... _Types> 542 using _Move_ctor_alias = 543 _Move_ctor_base<_Traits<_Types...>::_S_trivial_move_ctor, _Types...>; 544 545 template<bool, typename... _Types> 546 struct _Copy_assign_base : _Move_ctor_alias<_Types...> 547 { 548 using _Base = _Move_ctor_alias<_Types...>; 549 using _Base::_Base; 550 551 _Copy_assign_base& 552 operator=(const _Copy_assign_base& __rhs) 553 noexcept(_Traits<_Types...>::_S_nothrow_copy_assign) 554 { 555 if (this->_M_index == __rhs._M_index) 556 { 557 if (__rhs._M_valid()) 558 { 559 static constexpr void (*_S_vtable[])(void*, void*) = 560 { &__erased_assign<_Types&, const _Types&>... }; 561 _S_vtable[__rhs._M_index](this->_M_storage(), 562 __rhs._M_storage()); 563 } 564 } 565 else 566 { 567 _Copy_assign_base __tmp(__rhs); 568 this->_M_destructive_move(std::move(__tmp)); 569 } 570 __glibcxx_assert(this->_M_index == __rhs._M_index); 571 return *this; 572 } 573 574 _Copy_assign_base(const _Copy_assign_base&) = default; 575 _Copy_assign_base(_Copy_assign_base&&) = default; 576 _Copy_assign_base& operator=(_Copy_assign_base&&) = default; 577 }; 578 579 template<typename... _Types> 580 struct _Copy_assign_base<true, _Types...> : _Move_ctor_alias<_Types...> 581 { 582 using _Base = _Move_ctor_alias<_Types...>; 583 using _Base::_Base; 584 }; 585 586 template<typename... _Types> 587 using _Copy_assign_alias = 588 _Copy_assign_base<_Traits<_Types...>::_S_trivial_copy_assign, 589 _Types...>; 590 591 template<bool, typename... _Types> 592 struct _Move_assign_base : _Copy_assign_alias<_Types...> 593 { 594 using _Base = _Copy_assign_alias<_Types...>; 595 using _Base::_Base; 596 597 _Move_assign_base& 598 operator=(_Move_assign_base&& __rhs) 599 noexcept(_Traits<_Types...>::_S_nothrow_move_assign) 600 { 601 if (this->_M_index == __rhs._M_index) 602 { 603 if (__rhs._M_valid()) 604 { 605 static constexpr void (*_S_vtable[])(void*, void*) = 606 { &__erased_assign<_Types&, _Types&&>... }; 607 _S_vtable[__rhs._M_index] 608 (this->_M_storage(), __rhs._M_storage()); 609 } 610 } 611 else 612 { 613 _Move_assign_base __tmp(std::move(__rhs)); 614 this->_M_destructive_move(std::move(__tmp)); 615 } 616 __glibcxx_assert(this->_M_index == __rhs._M_index); 617 return *this; 618 } 619 620 _Move_assign_base(const _Move_assign_base&) = default; 621 _Move_assign_base(_Move_assign_base&&) = default; 622 _Move_assign_base& operator=(const _Move_assign_base&) = default; 623 }; 624 625 template<typename... _Types> 626 struct _Move_assign_base<true, _Types...> : _Copy_assign_alias<_Types...> 627 { 628 using _Base = _Copy_assign_alias<_Types...>; 629 using _Base::_Base; 630 }; 631 632 template<typename... _Types> 633 using _Move_assign_alias = 634 _Move_assign_base<_Traits<_Types...>::_S_trivial_move_assign, 635 _Types...>; 636 637 template<typename... _Types> 638 struct _Variant_base : _Move_assign_alias<_Types...> 639 { 640 using _Base = _Move_assign_alias<_Types...>; 641 642 constexpr 643 _Variant_base() 644 noexcept(_Traits<_Types...>::_S_nothrow_default_ctor) 645 : _Variant_base(in_place_index<0>) { } 646 647 template<size_t _Np, typename... _Args> 648 constexpr explicit 649 _Variant_base(in_place_index_t<_Np> __i, _Args&&... __args) 650 : _Base(__i, std::forward<_Args>(__args)...) 651 { } 652 653 _Variant_base(const _Variant_base&) = default; 654 _Variant_base(_Variant_base&&) = default; 655 _Variant_base& operator=(const _Variant_base&) = default; 656 _Variant_base& operator=(_Variant_base&&) = default; 657 }; 658 659 // For how many times does _Tp appear in _Tuple? 660 template<typename _Tp, typename _Tuple> 661 struct __tuple_count; 662 663 template<typename _Tp, typename _Tuple> 664 inline constexpr size_t __tuple_count_v = 665 __tuple_count<_Tp, _Tuple>::value; 666 667 template<typename _Tp, typename... _Types> 668 struct __tuple_count<_Tp, tuple<_Types...>> 669 : integral_constant<size_t, 0> { }; 670 671 template<typename _Tp, typename _First, typename... _Rest> 672 struct __tuple_count<_Tp, tuple<_First, _Rest...>> 673 : integral_constant< 674 size_t, 675 __tuple_count_v<_Tp, tuple<_Rest...>> + is_same_v<_Tp, _First>> { }; 676 677 // TODO: Reuse this in <tuple> ? 678 template<typename _Tp, typename... _Types> 679 inline constexpr bool __exactly_once = 680 __tuple_count_v<_Tp, tuple<_Types...>> == 1; 681 682 // Takes _Types and create an overloaded _S_fun for each type. 683 // If a type appears more than once in _Types, create only one overload. 684 template<typename... _Types> 685 struct __overload_set 686 { static void _S_fun(); }; 687 688 template<typename _First, typename... _Rest> 689 struct __overload_set<_First, _Rest...> : __overload_set<_Rest...> 690 { 691 using __overload_set<_Rest...>::_S_fun; 692 static integral_constant<size_t, sizeof...(_Rest)> _S_fun(_First); 693 }; 694 695 template<typename... _Rest> 696 struct __overload_set<void, _Rest...> : __overload_set<_Rest...> 697 { 698 using __overload_set<_Rest...>::_S_fun; 699 }; 700 701 // Helper for variant(_Tp&&) and variant::operator=(_Tp&&). 702 // __accepted_index maps the arbitrary _Tp to an alternative type in _Variant. 703 template<typename _Tp, typename _Variant, typename = void> 704 struct __accepted_index 705 { static constexpr size_t value = variant_npos; }; 706 707 template<typename _Tp, typename... _Types> 708 struct __accepted_index< 709 _Tp, variant<_Types...>, 710 decltype(__overload_set<_Types...>::_S_fun(std::declval<_Tp>()), 711 std::declval<void>())> 712 { 713 static constexpr size_t value = sizeof...(_Types) - 1 714 - decltype(__overload_set<_Types...>:: 715 _S_fun(std::declval<_Tp>()))::value; 716 }; 717 718 // Returns the raw storage for __v. 719 template<typename _Variant> 720 void* __get_storage(_Variant&& __v) 721 { return __v._M_storage(); } 722 723 // Used for storing multi-dimensional vtable. 724 template<typename _Tp, size_t... _Dimensions> 725 struct _Multi_array 726 { 727 constexpr const _Tp& 728 _M_access() const 729 { return _M_data; } 730 731 _Tp _M_data; 732 }; 733 734 template<typename _Tp, size_t __first, size_t... __rest> 735 struct _Multi_array<_Tp, __first, __rest...> 736 { 737 template<typename... _Args> 738 constexpr const _Tp& 739 _M_access(size_t __first_index, _Args... __rest_indices) const 740 { return _M_arr[__first_index]._M_access(__rest_indices...); } 741 742 _Multi_array<_Tp, __rest...> _M_arr[__first]; 743 }; 744 745 // Creates a multi-dimensional vtable recursively. 746 // 747 // For example, 748 // visit([](auto, auto){}, 749 // variant<int, char>(), // typedef'ed as V1 750 // variant<float, double, long double>()) // typedef'ed as V2 751 // will trigger instantiations of: 752 // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&), 2, 3>, 753 // tuple<V1&&, V2&&>, std::index_sequence<>> 754 // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&), 3>, 755 // tuple<V1&&, V2&&>, std::index_sequence<0>> 756 // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, 757 // tuple<V1&&, V2&&>, std::index_sequence<0, 0>> 758 // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, 759 // tuple<V1&&, V2&&>, std::index_sequence<0, 1>> 760 // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, 761 // tuple<V1&&, V2&&>, std::index_sequence<0, 2>> 762 // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&), 3>, 763 // tuple<V1&&, V2&&>, std::index_sequence<1>> 764 // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, 765 // tuple<V1&&, V2&&>, std::index_sequence<1, 0>> 766 // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, 767 // tuple<V1&&, V2&&>, std::index_sequence<1, 1>> 768 // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, 769 // tuple<V1&&, V2&&>, std::index_sequence<1, 2>> 770 // The returned multi-dimensional vtable can be fast accessed by the visitor 771 // using index calculation. 772 template<typename _Array_type, typename _Variant_tuple, typename _Index_seq> 773 struct __gen_vtable_impl; 774 775 template<typename _Result_type, typename _Visitor, size_t... __dimensions, 776 typename... _Variants, size_t... __indices> 777 struct __gen_vtable_impl< 778 _Multi_array<_Result_type (*)(_Visitor, _Variants...), __dimensions...>, 779 tuple<_Variants...>, std::index_sequence<__indices...>> 780 { 781 using _Next = 782 remove_reference_t<typename _Nth_type<sizeof...(__indices), 783 _Variants...>::type>; 784 using _Array_type = 785 _Multi_array<_Result_type (*)(_Visitor, _Variants...), 786 __dimensions...>; 787 788 static constexpr _Array_type 789 _S_apply() 790 { 791 _Array_type __vtable{}; 792 _S_apply_all_alts( 793 __vtable, make_index_sequence<variant_size_v<_Next>>()); 794 return __vtable; 795 } 796 797 template<size_t... __var_indices> 798 static constexpr void 799 _S_apply_all_alts(_Array_type& __vtable, 800 std::index_sequence<__var_indices...>) 801 { 802 (_S_apply_single_alt<__var_indices>( 803 __vtable._M_arr[__var_indices]), ...); 804 } 805 806 template<size_t __index, typename _Tp> 807 static constexpr void 808 _S_apply_single_alt(_Tp& __element) 809 { 810 using _Alternative = variant_alternative_t<__index, _Next>; 811 __element = __gen_vtable_impl< 812 remove_reference_t< 813 decltype(__element)>, tuple<_Variants...>, 814 std::index_sequence<__indices..., __index>>::_S_apply(); 815 } 816 }; 817 818 template<typename _Result_type, typename _Visitor, typename... _Variants, 819 size_t... __indices> 820 struct __gen_vtable_impl< 821 _Multi_array<_Result_type (*)(_Visitor, _Variants...)>, 822 tuple<_Variants...>, std::index_sequence<__indices...>> 823 { 824 using _Array_type = 825 _Multi_array<_Result_type (*)(_Visitor&&, _Variants...)>; 826 827 decltype(auto) 828 static constexpr __visit_invoke(_Visitor&& __visitor, _Variants... __vars) 829 { 830 return std::__invoke(std::forward<_Visitor>(__visitor), 831 std::get<__indices>(std::forward<_Variants>(__vars))...); 832 } 833 834 static constexpr auto 835 _S_apply() 836 { return _Array_type{&__visit_invoke}; } 837 }; 838 839 template<typename _Result_type, typename _Visitor, typename... _Variants> 840 struct __gen_vtable 841 { 842 using _Func_ptr = _Result_type (*)(_Visitor&&, _Variants...); 843 using _Array_type = 844 _Multi_array<_Func_ptr, 845 variant_size_v<remove_reference_t<_Variants>>...>; 846 847 static constexpr _Array_type 848 _S_apply() 849 { 850 return __gen_vtable_impl<_Array_type, tuple<_Variants...>, 851 std::index_sequence<>>::_S_apply(); 852 } 853 854 static constexpr auto _S_vtable = _S_apply(); 855 }; 856 857 template<size_t _Np, typename _Tp> 858 struct _Base_dedup : public _Tp { }; 859 860 template<typename _Variant, typename __indices> 861 struct _Variant_hash_base; 862 863 template<typename... _Types, size_t... __indices> 864 struct _Variant_hash_base<variant<_Types...>, 865 std::index_sequence<__indices...>> 866 : _Base_dedup<__indices, __poison_hash<remove_const_t<_Types>>>... { }; 867 868} // namespace __variant 869} // namespace __detail 870 871 template<typename _Tp, typename... _Types> 872 inline constexpr bool holds_alternative(const variant<_Types...>& __v) 873 noexcept 874 { 875 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, 876 "T should occur for exactly once in alternatives"); 877 return __v.index() == __detail::__variant::__index_of_v<_Tp, _Types...>; 878 } 879 880 template<typename _Tp, typename... _Types> 881 constexpr inline _Tp& get(variant<_Types...>& __v) 882 { 883 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, 884 "T should occur for exactly once in alternatives"); 885 static_assert(!is_void_v<_Tp>, "_Tp should not be void"); 886 return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v); 887 } 888 889 template<typename _Tp, typename... _Types> 890 constexpr inline _Tp&& get(variant<_Types...>&& __v) 891 { 892 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, 893 "T should occur for exactly once in alternatives"); 894 static_assert(!is_void_v<_Tp>, "_Tp should not be void"); 895 return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>( 896 std::move(__v)); 897 } 898 899 template<typename _Tp, typename... _Types> 900 constexpr inline const _Tp& get(const variant<_Types...>& __v) 901 { 902 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, 903 "T should occur for exactly once in alternatives"); 904 static_assert(!is_void_v<_Tp>, "_Tp should not be void"); 905 return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v); 906 } 907 908 template<typename _Tp, typename... _Types> 909 constexpr inline const _Tp&& get(const variant<_Types...>&& __v) 910 { 911 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, 912 "T should occur for exactly once in alternatives"); 913 static_assert(!is_void_v<_Tp>, "_Tp should not be void"); 914 return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>( 915 std::move(__v)); 916 } 917 918 template<size_t _Np, typename... _Types> 919 constexpr inline 920 add_pointer_t<variant_alternative_t<_Np, variant<_Types...>>> 921 get_if(variant<_Types...>* __ptr) noexcept 922 { 923 using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>; 924 static_assert(_Np < sizeof...(_Types), 925 "The index should be in [0, number of alternatives)"); 926 static_assert(!is_void_v<_Alternative_type>, "_Tp should not be void"); 927 if (__ptr && __ptr->index() == _Np) 928 return &__detail::__variant::__get<_Np>(*__ptr); 929 return nullptr; 930 } 931 932 template<size_t _Np, typename... _Types> 933 constexpr inline 934 add_pointer_t<const variant_alternative_t<_Np, variant<_Types...>>> 935 get_if(const variant<_Types...>* __ptr) noexcept 936 { 937 using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>; 938 static_assert(_Np < sizeof...(_Types), 939 "The index should be in [0, number of alternatives)"); 940 static_assert(!is_void_v<_Alternative_type>, "_Tp should not be void"); 941 if (__ptr && __ptr->index() == _Np) 942 return &__detail::__variant::__get<_Np>(*__ptr); 943 return nullptr; 944 } 945 946 template<typename _Tp, typename... _Types> 947 constexpr inline add_pointer_t<_Tp> 948 get_if(variant<_Types...>* __ptr) noexcept 949 { 950 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, 951 "T should occur for exactly once in alternatives"); 952 static_assert(!is_void_v<_Tp>, "_Tp should not be void"); 953 return std::get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>( 954 __ptr); 955 } 956 957 template<typename _Tp, typename... _Types> 958 constexpr inline add_pointer_t<const _Tp> 959 get_if(const variant<_Types...>* __ptr) 960 noexcept 961 { 962 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, 963 "T should occur for exactly once in alternatives"); 964 static_assert(!is_void_v<_Tp>, "_Tp should not be void"); 965 return std::get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>( 966 __ptr); 967 } 968 969 struct monostate { }; 970 971#define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP, __NAME) \ 972 template<typename... _Types> \ 973 constexpr bool operator __OP(const variant<_Types...>& __lhs, \ 974 const variant<_Types...>& __rhs) \ 975 { \ 976 return __lhs._M_##__NAME(__rhs, std::index_sequence_for<_Types...>{}); \ 977 } \ 978\ 979 constexpr bool operator __OP(monostate, monostate) noexcept \ 980 { return 0 __OP 0; } 981 982 _VARIANT_RELATION_FUNCTION_TEMPLATE(<, less) 983 _VARIANT_RELATION_FUNCTION_TEMPLATE(<=, less_equal) 984 _VARIANT_RELATION_FUNCTION_TEMPLATE(==, equal) 985 _VARIANT_RELATION_FUNCTION_TEMPLATE(!=, not_equal) 986 _VARIANT_RELATION_FUNCTION_TEMPLATE(>=, greater_equal) 987 _VARIANT_RELATION_FUNCTION_TEMPLATE(>, greater) 988 989#undef _VARIANT_RELATION_FUNCTION_TEMPLATE 990 991 template<typename _Visitor, typename... _Variants> 992 constexpr decltype(auto) visit(_Visitor&&, _Variants&&...); 993 994 template<typename... _Types> 995 inline enable_if_t<(is_move_constructible_v<_Types> && ...) 996 && (is_swappable_v<_Types> && ...)> 997 swap(variant<_Types...>& __lhs, variant<_Types...>& __rhs) 998 noexcept(noexcept(__lhs.swap(__rhs))) 999 { __lhs.swap(__rhs); } 1000 1001 template<typename... _Types> 1002 enable_if_t<!((is_move_constructible_v<_Types> && ...) 1003 && (is_swappable_v<_Types> && ...))> 1004 swap(variant<_Types...>&, variant<_Types...>&) = delete; 1005 1006 class bad_variant_access : public exception 1007 { 1008 public: 1009 bad_variant_access() noexcept : _M_reason("Unknown reason") { } 1010 const char* what() const noexcept override 1011 { return _M_reason; } 1012 1013 private: 1014 bad_variant_access(const char* __reason) : _M_reason(__reason) { } 1015 1016 const char* _M_reason; 1017 1018 friend void __throw_bad_variant_access(const char* __what); 1019 }; 1020 1021 inline void 1022 __throw_bad_variant_access(const char* __what) 1023 { _GLIBCXX_THROW_OR_ABORT(bad_variant_access(__what)); } 1024 1025 template<typename... _Types> 1026 class variant 1027 : private __detail::__variant::_Variant_base<_Types...>, 1028 private _Enable_default_constructor< 1029 __detail::__variant::_Traits<_Types...>::_S_default_ctor, 1030 variant<_Types...>>, 1031 private _Enable_copy_move< 1032 __detail::__variant::_Traits<_Types...>::_S_copy_ctor, 1033 __detail::__variant::_Traits<_Types...>::_S_copy_assign, 1034 __detail::__variant::_Traits<_Types...>::_S_move_ctor, 1035 __detail::__variant::_Traits<_Types...>::_S_move_assign, 1036 variant<_Types...>> 1037 { 1038 private: 1039 static_assert(sizeof...(_Types) > 0, 1040 "variant must have at least one alternative"); 1041 static_assert(!(std::is_reference_v<_Types> || ...), 1042 "variant must have no reference alternative"); 1043 static_assert(!(std::is_void_v<_Types> || ...), 1044 "variant must have no void alternative"); 1045 1046 using _Base = __detail::__variant::_Variant_base<_Types...>; 1047 using _Default_ctor_enabler = 1048 _Enable_default_constructor< 1049 __detail::__variant::_Traits<_Types...>::_S_default_ctor, 1050 variant<_Types...>>; 1051 1052 template<typename _Tp> 1053 static constexpr bool 1054 __exactly_once = __detail::__variant::__exactly_once<_Tp, _Types...>; 1055 1056 template<typename _Tp> 1057 static constexpr size_t __accepted_index = 1058 __detail::__variant::__accepted_index<_Tp&&, variant>::value; 1059 1060 template<size_t _Np, bool = _Np < sizeof...(_Types)> 1061 struct __to_type_impl; 1062 1063 template<size_t _Np> 1064 struct __to_type_impl<_Np, true> 1065 { using type = variant_alternative_t<_Np, variant>; }; 1066 1067 template<size_t _Np> 1068 using __to_type = typename __to_type_impl<_Np>::type; 1069 1070 template<typename _Tp> 1071 using __accepted_type = __to_type<__accepted_index<_Tp>>; 1072 1073 template<typename _Tp> 1074 static constexpr size_t __index_of = 1075 __detail::__variant::__index_of_v<_Tp, _Types...>; 1076 1077 using _Traits = __detail::__variant::_Traits<_Types...>; 1078 1079 public: 1080 variant() = default; 1081 variant(const variant& __rhs) = default; 1082 variant(variant&&) = default; 1083 variant& operator=(const variant&) = default; 1084 variant& operator=(variant&&) = default; 1085 ~variant() = default; 1086 1087 template<typename _Tp, 1088 typename = enable_if_t<!is_same_v<decay_t<_Tp>, variant>>, 1089 typename = enable_if_t<(sizeof...(_Types)>0)>, 1090 typename = enable_if_t<__exactly_once<__accepted_type<_Tp&&>> 1091 && is_constructible_v<__accepted_type<_Tp&&>, _Tp&&>>> 1092 constexpr 1093 variant(_Tp&& __t) 1094 noexcept(is_nothrow_constructible_v<__accepted_type<_Tp&&>, _Tp&&>) 1095 : variant(in_place_index<__accepted_index<_Tp&&>>, 1096 std::forward<_Tp>(__t)) 1097 { __glibcxx_assert(holds_alternative<__accepted_type<_Tp&&>>(*this)); } 1098 1099 template<typename _Tp, typename... _Args, 1100 typename = enable_if_t<__exactly_once<_Tp> 1101 && is_constructible_v<_Tp, _Args&&...>>> 1102 constexpr explicit 1103 variant(in_place_type_t<_Tp>, _Args&&... __args) 1104 : variant(in_place_index<__index_of<_Tp>>, 1105 std::forward<_Args>(__args)...) 1106 { __glibcxx_assert(holds_alternative<_Tp>(*this)); } 1107 1108 template<typename _Tp, typename _Up, typename... _Args, 1109 typename = enable_if_t<__exactly_once<_Tp> 1110 && is_constructible_v< 1111 _Tp, initializer_list<_Up>&, _Args&&...>>> 1112 constexpr explicit 1113 variant(in_place_type_t<_Tp>, initializer_list<_Up> __il, 1114 _Args&&... __args) 1115 : variant(in_place_index<__index_of<_Tp>>, __il, 1116 std::forward<_Args>(__args)...) 1117 { __glibcxx_assert(holds_alternative<_Tp>(*this)); } 1118 1119 template<size_t _Np, typename... _Args, 1120 typename = enable_if_t< 1121 is_constructible_v<__to_type<_Np>, _Args&&...>>> 1122 constexpr explicit 1123 variant(in_place_index_t<_Np>, _Args&&... __args) 1124 : _Base(in_place_index<_Np>, std::forward<_Args>(__args)...), 1125 _Default_ctor_enabler(_Enable_default_constructor_tag{}) 1126 { __glibcxx_assert(index() == _Np); } 1127 1128 template<size_t _Np, typename _Up, typename... _Args, 1129 typename = enable_if_t<is_constructible_v<__to_type<_Np>, 1130 initializer_list<_Up>&, _Args&&...>>> 1131 constexpr explicit 1132 variant(in_place_index_t<_Np>, initializer_list<_Up> __il, 1133 _Args&&... __args) 1134 : _Base(in_place_index<_Np>, __il, std::forward<_Args>(__args)...), 1135 _Default_ctor_enabler(_Enable_default_constructor_tag{}) 1136 { __glibcxx_assert(index() == _Np); } 1137 1138 template<typename _Tp> 1139 enable_if_t<__exactly_once<__accepted_type<_Tp&&>> 1140 && is_constructible_v<__accepted_type<_Tp&&>, _Tp&&> 1141 && is_assignable_v<__accepted_type<_Tp&&>&, _Tp&&> 1142 && !is_same_v<decay_t<_Tp>, variant>, variant&> 1143 operator=(_Tp&& __rhs) 1144 noexcept(is_nothrow_assignable_v<__accepted_type<_Tp&&>&, _Tp&&> 1145 && is_nothrow_constructible_v<__accepted_type<_Tp&&>, _Tp&&>) 1146 { 1147 constexpr auto __index = __accepted_index<_Tp&&>; 1148 if (index() == __index) 1149 std::get<__index>(*this) = std::forward<_Tp>(__rhs); 1150 else 1151 this->emplace<__index>(std::forward<_Tp>(__rhs)); 1152 __glibcxx_assert(holds_alternative<__accepted_type<_Tp&&>>(*this)); 1153 return *this; 1154 } 1155 1156 template<typename _Tp, typename... _Args> 1157 enable_if_t<is_constructible_v<_Tp, _Args...> && __exactly_once<_Tp>, 1158 _Tp&> 1159 emplace(_Args&&... __args) 1160 { 1161 auto& ret = 1162 this->emplace<__index_of<_Tp>>(std::forward<_Args>(__args)...); 1163 __glibcxx_assert(holds_alternative<_Tp>(*this)); 1164 return ret; 1165 } 1166 1167 template<typename _Tp, typename _Up, typename... _Args> 1168 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...> 1169 && __exactly_once<_Tp>, 1170 _Tp&> 1171 emplace(initializer_list<_Up> __il, _Args&&... __args) 1172 { 1173 auto& ret = 1174 this->emplace<__index_of<_Tp>>(__il, 1175 std::forward<_Args>(__args)...); 1176 __glibcxx_assert(holds_alternative<_Tp>(*this)); 1177 return ret; 1178 } 1179 1180 template<size_t _Np, typename... _Args> 1181 enable_if_t<is_constructible_v<variant_alternative_t<_Np, variant>, 1182 _Args...>, 1183 variant_alternative_t<_Np, variant>&> 1184 emplace(_Args&&... __args) 1185 { 1186 static_assert(_Np < sizeof...(_Types), 1187 "The index should be in [0, number of alternatives)"); 1188 this->~variant(); 1189 __try 1190 { 1191 ::new (this) variant(in_place_index<_Np>, 1192 std::forward<_Args>(__args)...); 1193 } 1194 __catch (...) 1195 { 1196 this->_M_index = variant_npos; 1197 __throw_exception_again; 1198 } 1199 __glibcxx_assert(index() == _Np); 1200 return std::get<_Np>(*this); 1201 } 1202 1203 template<size_t _Np, typename _Up, typename... _Args> 1204 enable_if_t<is_constructible_v<variant_alternative_t<_Np, variant>, 1205 initializer_list<_Up>&, _Args...>, 1206 variant_alternative_t<_Np, variant>&> 1207 emplace(initializer_list<_Up> __il, _Args&&... __args) 1208 { 1209 static_assert(_Np < sizeof...(_Types), 1210 "The index should be in [0, number of alternatives)"); 1211 this->~variant(); 1212 __try 1213 { 1214 ::new (this) variant(in_place_index<_Np>, __il, 1215 std::forward<_Args>(__args)...); 1216 } 1217 __catch (...) 1218 { 1219 this->_M_index = variant_npos; 1220 __throw_exception_again; 1221 } 1222 __glibcxx_assert(index() == _Np); 1223 return std::get<_Np>(*this); 1224 } 1225 1226 constexpr bool valueless_by_exception() const noexcept 1227 { return !this->_M_valid(); } 1228 1229 constexpr size_t index() const noexcept 1230 { 1231 if (this->_M_index == 1232 typename _Base::__index_type(variant_npos)) 1233 return variant_npos; 1234 return this->_M_index; 1235 } 1236 1237 void 1238 swap(variant& __rhs) 1239 noexcept((__is_nothrow_swappable<_Types>::value && ...) 1240 && is_nothrow_move_constructible_v<variant>) 1241 { 1242 if (this->index() == __rhs.index()) 1243 { 1244 if (this->_M_valid()) 1245 { 1246 static constexpr void (*_S_vtable[])(void*, void*) = 1247 { &__detail::__variant::__erased_swap<_Types&, _Types&>... }; 1248 _S_vtable[__rhs._M_index](this->_M_storage(), 1249 __rhs._M_storage()); 1250 } 1251 } 1252 else if (!this->_M_valid()) 1253 { 1254 this->_M_destructive_move(std::move(__rhs)); 1255 __rhs._M_reset(); 1256 } 1257 else if (!__rhs._M_valid()) 1258 { 1259 __rhs._M_destructive_move(std::move(*this)); 1260 this->_M_reset(); 1261 } 1262 else 1263 { 1264 auto __tmp = std::move(__rhs); 1265 __rhs._M_destructive_move(std::move(*this)); 1266 this->_M_destructive_move(std::move(__tmp)); 1267 } 1268 } 1269 1270 private: 1271#define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP, __NAME) \ 1272 template<size_t... __indices> \ 1273 static constexpr bool \ 1274 (*_S_erased_##__NAME[])(const variant&, const variant&) = \ 1275 { &__detail::__variant::__erased_##__NAME< \ 1276 const variant&, __indices>... }; \ 1277 template<size_t... __indices> \ 1278 constexpr inline bool \ 1279 _M_##__NAME(const variant& __rhs, \ 1280 std::index_sequence<__indices...>) const \ 1281 { \ 1282 auto __lhs_index = this->index(); \ 1283 auto __rhs_index = __rhs.index(); \ 1284 if (__lhs_index != __rhs_index || valueless_by_exception()) \ 1285 /* Modulo addition. */ \ 1286 return __lhs_index + 1 __OP __rhs_index + 1; \ 1287 return _S_erased_##__NAME<__indices...>[__lhs_index](*this, __rhs); \ 1288 } 1289 1290 _VARIANT_RELATION_FUNCTION_TEMPLATE(<, less) 1291 _VARIANT_RELATION_FUNCTION_TEMPLATE(<=, less_equal) 1292 _VARIANT_RELATION_FUNCTION_TEMPLATE(==, equal) 1293 _VARIANT_RELATION_FUNCTION_TEMPLATE(!=, not_equal) 1294 _VARIANT_RELATION_FUNCTION_TEMPLATE(>=, greater_equal) 1295 _VARIANT_RELATION_FUNCTION_TEMPLATE(>, greater) 1296 1297#undef _VARIANT_RELATION_FUNCTION_TEMPLATE 1298 1299#ifdef __clang__ 1300 public: 1301 using _Base::_M_u; // See https://bugs.llvm.org/show_bug.cgi?id=31852 1302 private: 1303#endif 1304 1305 template<size_t _Np, typename _Vp> 1306 friend constexpr decltype(auto) __detail::__variant::__get(_Vp&& __v); 1307 1308 template<typename _Vp> 1309 friend void* __detail::__variant::__get_storage(_Vp&& __v); 1310 1311#define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP) \ 1312 template<typename... _Tp> \ 1313 friend constexpr bool \ 1314 operator __OP(const variant<_Tp...>& __lhs, \ 1315 const variant<_Tp...>& __rhs); 1316 1317 _VARIANT_RELATION_FUNCTION_TEMPLATE(<) 1318 _VARIANT_RELATION_FUNCTION_TEMPLATE(<=) 1319 _VARIANT_RELATION_FUNCTION_TEMPLATE(==) 1320 _VARIANT_RELATION_FUNCTION_TEMPLATE(!=) 1321 _VARIANT_RELATION_FUNCTION_TEMPLATE(>=) 1322 _VARIANT_RELATION_FUNCTION_TEMPLATE(>) 1323 1324#undef _VARIANT_RELATION_FUNCTION_TEMPLATE 1325 }; 1326 1327 template<size_t _Np, typename... _Types> 1328 constexpr variant_alternative_t<_Np, variant<_Types...>>& 1329 get(variant<_Types...>& __v) 1330 { 1331 static_assert(_Np < sizeof...(_Types), 1332 "The index should be in [0, number of alternatives)"); 1333 if (__v.index() != _Np) 1334 __throw_bad_variant_access("Unexpected index"); 1335 return __detail::__variant::__get<_Np>(__v); 1336 } 1337 1338 template<size_t _Np, typename... _Types> 1339 constexpr variant_alternative_t<_Np, variant<_Types...>>&& 1340 get(variant<_Types...>&& __v) 1341 { 1342 static_assert(_Np < sizeof...(_Types), 1343 "The index should be in [0, number of alternatives)"); 1344 if (__v.index() != _Np) 1345 __throw_bad_variant_access("Unexpected index"); 1346 return __detail::__variant::__get<_Np>(std::move(__v)); 1347 } 1348 1349 template<size_t _Np, typename... _Types> 1350 constexpr const variant_alternative_t<_Np, variant<_Types...>>& 1351 get(const variant<_Types...>& __v) 1352 { 1353 static_assert(_Np < sizeof...(_Types), 1354 "The index should be in [0, number of alternatives)"); 1355 if (__v.index() != _Np) 1356 __throw_bad_variant_access("Unexpected index"); 1357 return __detail::__variant::__get<_Np>(__v); 1358 } 1359 1360 template<size_t _Np, typename... _Types> 1361 constexpr const variant_alternative_t<_Np, variant<_Types...>>&& 1362 get(const variant<_Types...>&& __v) 1363 { 1364 static_assert(_Np < sizeof...(_Types), 1365 "The index should be in [0, number of alternatives)"); 1366 if (__v.index() != _Np) 1367 __throw_bad_variant_access("Unexpected index"); 1368 return __detail::__variant::__get<_Np>(std::move(__v)); 1369 } 1370 1371 template<typename _Visitor, typename... _Variants> 1372 constexpr decltype(auto) 1373 visit(_Visitor&& __visitor, _Variants&&... __variants) 1374 { 1375 if ((__variants.valueless_by_exception() || ...)) 1376 __throw_bad_variant_access("Unexpected index"); 1377 1378 using _Result_type = 1379 decltype(std::forward<_Visitor>(__visitor)( 1380 std::get<0>(std::forward<_Variants>(__variants))...)); 1381 1382 constexpr auto& __vtable = __detail::__variant::__gen_vtable< 1383 _Result_type, _Visitor&&, _Variants&&...>::_S_vtable; 1384 1385 auto __func_ptr = __vtable._M_access(__variants.index()...); 1386 return (*__func_ptr)(std::forward<_Visitor>(__visitor), 1387 std::forward<_Variants>(__variants)...); 1388 } 1389 1390 template<bool, typename... _Types> 1391 struct __variant_hash_call_base_impl 1392 { 1393 size_t 1394 operator()(const variant<_Types...>& __t) const 1395 noexcept((is_nothrow_invocable_v<hash<decay_t<_Types>>, _Types> && ...)) 1396 { 1397 if (!__t.valueless_by_exception()) 1398 { 1399 namespace __edv = __detail::__variant; 1400 static constexpr size_t (*_S_vtable[])(void*) = 1401 { &__edv::__erased_hash<const _Types&>... }; 1402 return hash<size_t>{}(__t.index()) 1403 + _S_vtable[__t.index()](__edv::__get_storage(__t)); 1404 } 1405 return hash<size_t>{}(__t.index()); 1406 } 1407 }; 1408 1409 template<typename... _Types> 1410 struct __variant_hash_call_base_impl<false, _Types...> {}; 1411 1412 template<typename... _Types> 1413 using __variant_hash_call_base = 1414 __variant_hash_call_base_impl<(__poison_hash<remove_const_t<_Types>>:: 1415 __enable_hash_call &&...), _Types...>; 1416 1417 template<typename... _Types> 1418 struct hash<variant<_Types...>> 1419 : private __detail::__variant::_Variant_hash_base< 1420 variant<_Types...>, std::index_sequence_for<_Types...>>, 1421 public __variant_hash_call_base<_Types...> 1422 { 1423 using result_type [[__deprecated__]] = size_t; 1424 using argument_type [[__deprecated__]] = variant<_Types...>; 1425 }; 1426 1427 template<> 1428 struct hash<monostate> 1429 { 1430 using result_type [[__deprecated__]] = size_t; 1431 using argument_type [[__deprecated__]] = monostate; 1432 1433 size_t 1434 operator()(const monostate& __t) const noexcept 1435 { 1436 constexpr size_t __magic_monostate_hash = -7777; 1437 return __magic_monostate_hash; 1438 } 1439 }; 1440 1441 template<typename... _Types> 1442 struct __is_fast_hash<hash<variant<_Types...>>> 1443 : bool_constant<(__is_fast_hash<_Types>::value && ...)> 1444 { }; 1445 1446_GLIBCXX_END_NAMESPACE_VERSION 1447} // namespace std 1448 1449#endif // C++17 1450 1451#endif // _GLIBCXX_VARIANT 1452