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52e86221 VV |
1 | // <any> -*- C++ -*- |
2 | ||
99dee823 | 3 | // Copyright (C) 2014-2021 Free Software Foundation, Inc. |
52e86221 VV |
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 include/any | |
26 | * This is a Standard C++ Library header. | |
27 | */ | |
28 | ||
29 | #ifndef _GLIBCXX_ANY | |
30 | #define _GLIBCXX_ANY 1 | |
31 | ||
32 | #pragma GCC system_header | |
33 | ||
c6888c62 | 34 | #if __cplusplus >= 201703L |
52e86221 | 35 | |
261d5a4a | 36 | #include <initializer_list> |
52e86221 VV |
37 | #include <typeinfo> |
38 | #include <new> | |
52e86221 | 39 | #include <type_traits> |
261d5a4a | 40 | #include <bits/utility.h> // in_place_type_t |
52e86221 VV |
41 | |
42 | namespace std _GLIBCXX_VISIBILITY(default) | |
43 | { | |
44 | _GLIBCXX_BEGIN_NAMESPACE_VERSION | |
45 | ||
46 | /** | |
47 | * @addtogroup utilities | |
48 | * @{ | |
49 | */ | |
50 | ||
51 | /** | |
52 | * @brief Exception class thrown by a failed @c any_cast | |
53 | * @ingroup exceptions | |
54 | */ | |
55 | class bad_any_cast : public bad_cast | |
56 | { | |
57 | public: | |
58 | virtual const char* what() const noexcept { return "bad any_cast"; } | |
59 | }; | |
60 | ||
61 | [[gnu::noreturn]] inline void __throw_bad_any_cast() | |
62 | { | |
63 | #if __cpp_exceptions | |
64 | throw bad_any_cast{}; | |
65 | #else | |
66 | __builtin_abort(); | |
67 | #endif | |
68 | } | |
69 | ||
56a9eaf9 | 70 | #define __cpp_lib_any 201606L |
c6888c62 | 71 | |
52e86221 VV |
72 | /** |
73 | * @brief A type-safe container of any type. | |
73ebece3 | 74 | * |
52e86221 VV |
75 | * An @c any object's state is either empty or it stores a contained object |
76 | * of CopyConstructible type. | |
77 | */ | |
78 | class any | |
79 | { | |
80 | // Holds either pointer to a heap object or the contained object itself. | |
81 | union _Storage | |
82 | { | |
25a69162 | 83 | constexpr _Storage() : _M_ptr{nullptr} {} |
52e86221 VV |
84 | |
85 | // Prevent trivial copies of this type, buffer might hold a non-POD. | |
86 | _Storage(const _Storage&) = delete; | |
87 | _Storage& operator=(const _Storage&) = delete; | |
88 | ||
89 | void* _M_ptr; | |
90 | aligned_storage<sizeof(_M_ptr), alignof(void*)>::type _M_buffer; | |
91 | }; | |
92 | ||
93 | template<typename _Tp, typename _Safe = is_nothrow_move_constructible<_Tp>, | |
94 | bool _Fits = (sizeof(_Tp) <= sizeof(_Storage)) | |
95 | && (alignof(_Tp) <= alignof(_Storage))> | |
96 | using _Internal = std::integral_constant<bool, _Safe::value && _Fits>; | |
97 | ||
98 | template<typename _Tp> | |
99 | struct _Manager_internal; // uses small-object optimization | |
100 | ||
101 | template<typename _Tp> | |
102 | struct _Manager_external; // creates contained object on the heap | |
103 | ||
104 | template<typename _Tp> | |
a09bb4a8 JW |
105 | using _Manager = __conditional_t<_Internal<_Tp>::value, |
106 | _Manager_internal<_Tp>, | |
107 | _Manager_external<_Tp>>; | |
52e86221 | 108 | |
d1462b07 JW |
109 | template<typename _Tp, typename _VTp = decay_t<_Tp>> |
110 | using _Decay_if_not_any = enable_if_t<!is_same_v<_VTp, any>, _VTp>; | |
52e86221 | 111 | |
ca9e949f VV |
112 | /// Emplace with an object created from @p __args as the contained object. |
113 | template <typename _Tp, typename... _Args, | |
114 | typename _Mgr = _Manager<_Tp>> | |
115 | void __do_emplace(_Args&&... __args) | |
116 | { | |
117 | reset(); | |
ca9e949f | 118 | _Mgr::_S_create(_M_storage, std::forward<_Args>(__args)...); |
73ebece3 | 119 | _M_manager = &_Mgr::_S_manage; |
ca9e949f VV |
120 | } |
121 | ||
122 | /// Emplace with an object created from @p __il and @p __args as | |
123 | /// the contained object. | |
124 | template <typename _Tp, typename _Up, typename... _Args, | |
125 | typename _Mgr = _Manager<_Tp>> | |
126 | void __do_emplace(initializer_list<_Up> __il, _Args&&... __args) | |
127 | { | |
128 | reset(); | |
d1462b07 | 129 | _Mgr::_S_create(_M_storage, __il, std::forward<_Args>(__args)...); |
73ebece3 | 130 | _M_manager = &_Mgr::_S_manage; |
ca9e949f VV |
131 | } |
132 | ||
d1462b07 JW |
133 | template <typename _Res, typename _Tp, typename... _Args> |
134 | using __any_constructible | |
135 | = enable_if<__and_<is_copy_constructible<_Tp>, | |
136 | is_constructible<_Tp, _Args...>>::value, | |
137 | _Res>; | |
138 | ||
139 | template <typename _Tp, typename... _Args> | |
140 | using __any_constructible_t | |
141 | = typename __any_constructible<bool, _Tp, _Args...>::type; | |
142 | ||
143 | template<typename _VTp, typename... _Args> | |
144 | using __emplace_t | |
145 | = typename __any_constructible<_VTp&, _VTp, _Args...>::type; | |
146 | ||
52e86221 VV |
147 | public: |
148 | // construct/destruct | |
149 | ||
150 | /// Default constructor, creates an empty object. | |
25a69162 | 151 | constexpr any() noexcept : _M_manager(nullptr) { } |
52e86221 VV |
152 | |
153 | /// Copy constructor, copies the state of @p __other | |
154 | any(const any& __other) | |
155 | { | |
25a69162 | 156 | if (!__other.has_value()) |
52e86221 VV |
157 | _M_manager = nullptr; |
158 | else | |
159 | { | |
160 | _Arg __arg; | |
161 | __arg._M_any = this; | |
162 | __other._M_manager(_Op_clone, &__other, &__arg); | |
163 | } | |
164 | } | |
165 | ||
166 | /** | |
167 | * @brief Move constructor, transfer the state from @p __other | |
168 | * | |
25a69162 | 169 | * @post @c !__other.has_value() (this postcondition is a GNU extension) |
52e86221 VV |
170 | */ |
171 | any(any&& __other) noexcept | |
172 | { | |
25a69162 | 173 | if (!__other.has_value()) |
52e86221 VV |
174 | _M_manager = nullptr; |
175 | else | |
176 | { | |
177 | _Arg __arg; | |
178 | __arg._M_any = this; | |
179 | __other._M_manager(_Op_xfer, &__other, &__arg); | |
180 | } | |
181 | } | |
182 | ||
183 | /// Construct with a copy of @p __value as the contained object. | |
d1462b07 JW |
184 | template <typename _Tp, typename _VTp = _Decay_if_not_any<_Tp>, |
185 | typename _Mgr = _Manager<_VTp>, | |
186 | enable_if_t<is_copy_constructible<_VTp>::value | |
187 | && !__is_in_place_type<_VTp>::value, bool> = true> | |
188 | any(_Tp&& __value) | |
52e86221 VV |
189 | : _M_manager(&_Mgr::_S_manage) |
190 | { | |
d1462b07 | 191 | _Mgr::_S_create(_M_storage, std::forward<_Tp>(__value)); |
52e86221 VV |
192 | } |
193 | ||
25a69162 | 194 | /// Construct with an object created from @p __args as the contained object. |
d1462b07 JW |
195 | template <typename _Tp, typename... _Args, typename _VTp = decay_t<_Tp>, |
196 | typename _Mgr = _Manager<_VTp>, | |
197 | __any_constructible_t<_VTp, _Args&&...> = false> | |
1725d05d | 198 | explicit |
d1462b07 | 199 | any(in_place_type_t<_Tp>, _Args&&... __args) |
25a69162 VV |
200 | : _M_manager(&_Mgr::_S_manage) |
201 | { | |
d1462b07 | 202 | _Mgr::_S_create(_M_storage, std::forward<_Args>(__args)...); |
25a69162 VV |
203 | } |
204 | ||
205 | /// Construct with an object created from @p __il and @p __args as | |
206 | /// the contained object. | |
d1462b07 JW |
207 | template <typename _Tp, typename _Up, typename... _Args, |
208 | typename _VTp = decay_t<_Tp>, typename _Mgr = _Manager<_VTp>, | |
14f26c75 | 209 | __any_constructible_t<_VTp, initializer_list<_Up>&, |
25a69162 | 210 | _Args&&...> = false> |
1725d05d | 211 | explicit |
d1462b07 | 212 | any(in_place_type_t<_Tp>, initializer_list<_Up> __il, _Args&&... __args) |
25a69162 VV |
213 | : _M_manager(&_Mgr::_S_manage) |
214 | { | |
d1462b07 | 215 | _Mgr::_S_create(_M_storage, __il, std::forward<_Args>(__args)...); |
25a69162 VV |
216 | } |
217 | ||
218 | /// Destructor, calls @c reset() | |
219 | ~any() { reset(); } | |
52e86221 VV |
220 | |
221 | // assignments | |
222 | ||
223 | /// Copy the state of another object. | |
d1462b07 JW |
224 | any& |
225 | operator=(const any& __rhs) | |
52e86221 | 226 | { |
1725d05d | 227 | *this = any(__rhs); |
52e86221 VV |
228 | return *this; |
229 | } | |
230 | ||
231 | /** | |
232 | * @brief Move assignment operator | |
233 | * | |
25a69162 | 234 | * @post @c !__rhs.has_value() (not guaranteed for other implementations) |
52e86221 | 235 | */ |
d1462b07 JW |
236 | any& |
237 | operator=(any&& __rhs) noexcept | |
52e86221 | 238 | { |
25a69162 VV |
239 | if (!__rhs.has_value()) |
240 | reset(); | |
52e86221 VV |
241 | else if (this != &__rhs) |
242 | { | |
1725d05d | 243 | reset(); |
52e86221 VV |
244 | _Arg __arg; |
245 | __arg._M_any = this; | |
246 | __rhs._M_manager(_Op_xfer, &__rhs, &__arg); | |
247 | } | |
248 | return *this; | |
249 | } | |
250 | ||
251 | /// Store a copy of @p __rhs as the contained object. | |
d1462b07 JW |
252 | template<typename _Tp> |
253 | enable_if_t<is_copy_constructible<_Decay_if_not_any<_Tp>>::value, any&> | |
254 | operator=(_Tp&& __rhs) | |
52e86221 | 255 | { |
d1462b07 | 256 | *this = any(std::forward<_Tp>(__rhs)); |
52e86221 VV |
257 | return *this; |
258 | } | |
259 | ||
25a69162 | 260 | /// Emplace with an object created from @p __args as the contained object. |
d1462b07 JW |
261 | template <typename _Tp, typename... _Args> |
262 | __emplace_t<decay_t<_Tp>, _Args...> | |
ca9e949f | 263 | emplace(_Args&&... __args) |
25a69162 | 264 | { |
d1462b07 JW |
265 | using _VTp = decay_t<_Tp>; |
266 | __do_emplace<_VTp>(std::forward<_Args>(__args)...); | |
f6bb145c | 267 | return *any::_Manager<_VTp>::_S_access(_M_storage); |
25a69162 VV |
268 | } |
269 | ||
270 | /// Emplace with an object created from @p __il and @p __args as | |
271 | /// the contained object. | |
d1462b07 | 272 | template <typename _Tp, typename _Up, typename... _Args> |
14f26c75 | 273 | __emplace_t<decay_t<_Tp>, initializer_list<_Up>&, _Args&&...> |
ca9e949f | 274 | emplace(initializer_list<_Up> __il, _Args&&... __args) |
25a69162 | 275 | { |
d1462b07 JW |
276 | using _VTp = decay_t<_Tp>; |
277 | __do_emplace<_VTp, _Up>(__il, std::forward<_Args>(__args)...); | |
f6bb145c | 278 | return *any::_Manager<_VTp>::_S_access(_M_storage); |
25a69162 VV |
279 | } |
280 | ||
52e86221 VV |
281 | // modifiers |
282 | ||
283 | /// If not empty, destroy the contained object. | |
25a69162 | 284 | void reset() noexcept |
52e86221 | 285 | { |
25a69162 | 286 | if (has_value()) |
52e86221 VV |
287 | { |
288 | _M_manager(_Op_destroy, this, nullptr); | |
289 | _M_manager = nullptr; | |
290 | } | |
291 | } | |
292 | ||
293 | /// Exchange state with another object. | |
294 | void swap(any& __rhs) noexcept | |
295 | { | |
25a69162 | 296 | if (!has_value() && !__rhs.has_value()) |
52e86221 VV |
297 | return; |
298 | ||
25a69162 | 299 | if (has_value() && __rhs.has_value()) |
52e86221 VV |
300 | { |
301 | if (this == &__rhs) | |
302 | return; | |
303 | ||
304 | any __tmp; | |
305 | _Arg __arg; | |
306 | __arg._M_any = &__tmp; | |
307 | __rhs._M_manager(_Op_xfer, &__rhs, &__arg); | |
308 | __arg._M_any = &__rhs; | |
309 | _M_manager(_Op_xfer, this, &__arg); | |
310 | __arg._M_any = this; | |
311 | __tmp._M_manager(_Op_xfer, &__tmp, &__arg); | |
312 | } | |
313 | else | |
314 | { | |
25a69162 VV |
315 | any* __empty = !has_value() ? this : &__rhs; |
316 | any* __full = !has_value() ? &__rhs : this; | |
52e86221 VV |
317 | _Arg __arg; |
318 | __arg._M_any = __empty; | |
319 | __full->_M_manager(_Op_xfer, __full, &__arg); | |
320 | } | |
321 | } | |
322 | ||
323 | // observers | |
324 | ||
325 | /// Reports whether there is a contained object or not. | |
25a69162 | 326 | bool has_value() const noexcept { return _M_manager != nullptr; } |
52e86221 VV |
327 | |
328 | #if __cpp_rtti | |
329 | /// The @c typeid of the contained object, or @c typeid(void) if empty. | |
330 | const type_info& type() const noexcept | |
331 | { | |
25a69162 | 332 | if (!has_value()) |
52e86221 VV |
333 | return typeid(void); |
334 | _Arg __arg; | |
335 | _M_manager(_Op_get_type_info, this, &__arg); | |
336 | return *__arg._M_typeinfo; | |
337 | } | |
338 | #endif | |
339 | ||
340 | template<typename _Tp> | |
341 | static constexpr bool __is_valid_cast() | |
342 | { return __or_<is_reference<_Tp>, is_copy_constructible<_Tp>>::value; } | |
343 | ||
344 | private: | |
345 | enum _Op { | |
346 | _Op_access, _Op_get_type_info, _Op_clone, _Op_destroy, _Op_xfer | |
347 | }; | |
348 | ||
349 | union _Arg | |
350 | { | |
351 | void* _M_obj; | |
352 | const std::type_info* _M_typeinfo; | |
353 | any* _M_any; | |
354 | }; | |
355 | ||
356 | void (*_M_manager)(_Op, const any*, _Arg*); | |
357 | _Storage _M_storage; | |
358 | ||
359 | template<typename _Tp> | |
360 | friend void* __any_caster(const any* __any); | |
361 | ||
362 | // Manage in-place contained object. | |
363 | template<typename _Tp> | |
364 | struct _Manager_internal | |
365 | { | |
366 | static void | |
367 | _S_manage(_Op __which, const any* __anyp, _Arg* __arg); | |
368 | ||
369 | template<typename _Up> | |
370 | static void | |
371 | _S_create(_Storage& __storage, _Up&& __value) | |
372 | { | |
373 | void* __addr = &__storage._M_buffer; | |
374 | ::new (__addr) _Tp(std::forward<_Up>(__value)); | |
375 | } | |
25a69162 VV |
376 | |
377 | template<typename... _Args> | |
378 | static void | |
379 | _S_create(_Storage& __storage, _Args&&... __args) | |
380 | { | |
381 | void* __addr = &__storage._M_buffer; | |
382 | ::new (__addr) _Tp(std::forward<_Args>(__args)...); | |
383 | } | |
f6bb145c TA |
384 | |
385 | static _Tp* | |
386 | _S_access(const _Storage& __storage) | |
387 | { | |
388 | // The contained object is in __storage._M_buffer | |
389 | const void* __addr = &__storage._M_buffer; | |
390 | return static_cast<_Tp*>(const_cast<void*>(__addr)); | |
391 | } | |
52e86221 VV |
392 | }; |
393 | ||
394 | // Manage external contained object. | |
395 | template<typename _Tp> | |
396 | struct _Manager_external | |
397 | { | |
398 | static void | |
399 | _S_manage(_Op __which, const any* __anyp, _Arg* __arg); | |
400 | ||
401 | template<typename _Up> | |
402 | static void | |
403 | _S_create(_Storage& __storage, _Up&& __value) | |
404 | { | |
405 | __storage._M_ptr = new _Tp(std::forward<_Up>(__value)); | |
406 | } | |
25a69162 VV |
407 | template<typename... _Args> |
408 | static void | |
409 | _S_create(_Storage& __storage, _Args&&... __args) | |
410 | { | |
411 | __storage._M_ptr = new _Tp(std::forward<_Args>(__args)...); | |
412 | } | |
f6bb145c TA |
413 | static _Tp* |
414 | _S_access(const _Storage& __storage) | |
415 | { | |
416 | // The contained object is in *__storage._M_ptr | |
417 | return static_cast<_Tp*>(__storage._M_ptr); | |
418 | } | |
52e86221 VV |
419 | }; |
420 | }; | |
421 | ||
422 | /// Exchange the states of two @c any objects. | |
423 | inline void swap(any& __x, any& __y) noexcept { __x.swap(__y); } | |
424 | ||
25a69162 VV |
425 | /// Create an any holding a @c _Tp constructed from @c __args. |
426 | template <typename _Tp, typename... _Args> | |
427 | any make_any(_Args&&... __args) | |
428 | { | |
627a2f59 | 429 | return any(in_place_type<_Tp>, std::forward<_Args>(__args)...); |
25a69162 VV |
430 | } |
431 | ||
432 | /// Create an any holding a @c _Tp constructed from @c __il and @c __args. | |
433 | template <typename _Tp, typename _Up, typename... _Args> | |
434 | any make_any(initializer_list<_Up> __il, _Args&&... __args) | |
435 | { | |
627a2f59 | 436 | return any(in_place_type<_Tp>, __il, std::forward<_Args>(__args)...); |
25a69162 VV |
437 | } |
438 | ||
52e86221 VV |
439 | /** |
440 | * @brief Access the contained object. | |
441 | * | |
442 | * @tparam _ValueType A const-reference or CopyConstructible type. | |
443 | * @param __any The object to access. | |
444 | * @return The contained object. | |
445 | * @throw bad_any_cast If <code> | |
446 | * __any.type() != typeid(remove_reference_t<_ValueType>) | |
447 | * </code> | |
448 | */ | |
449 | template<typename _ValueType> | |
450 | inline _ValueType any_cast(const any& __any) | |
451 | { | |
6791489e | 452 | using _Up = __remove_cvref_t<_ValueType>; |
52e86221 VV |
453 | static_assert(any::__is_valid_cast<_ValueType>(), |
454 | "Template argument must be a reference or CopyConstructible type"); | |
23c3a059 VV |
455 | static_assert(is_constructible_v<_ValueType, const _Up&>, |
456 | "Template argument must be constructible from a const value."); | |
457 | auto __p = any_cast<_Up>(&__any); | |
52e86221 | 458 | if (__p) |
62549523 | 459 | return static_cast<_ValueType>(*__p); |
52e86221 VV |
460 | __throw_bad_any_cast(); |
461 | } | |
462 | ||
463 | /** | |
464 | * @brief Access the contained object. | |
465 | * | |
466 | * @tparam _ValueType A reference or CopyConstructible type. | |
467 | * @param __any The object to access. | |
468 | * @return The contained object. | |
469 | * @throw bad_any_cast If <code> | |
470 | * __any.type() != typeid(remove_reference_t<_ValueType>) | |
471 | * </code> | |
472 | * | |
473 | * @{ | |
474 | */ | |
475 | template<typename _ValueType> | |
476 | inline _ValueType any_cast(any& __any) | |
477 | { | |
6791489e | 478 | using _Up = __remove_cvref_t<_ValueType>; |
52e86221 VV |
479 | static_assert(any::__is_valid_cast<_ValueType>(), |
480 | "Template argument must be a reference or CopyConstructible type"); | |
23c3a059 VV |
481 | static_assert(is_constructible_v<_ValueType, _Up&>, |
482 | "Template argument must be constructible from an lvalue."); | |
483 | auto __p = any_cast<_Up>(&__any); | |
52e86221 | 484 | if (__p) |
62549523 | 485 | return static_cast<_ValueType>(*__p); |
52e86221 VV |
486 | __throw_bad_any_cast(); |
487 | } | |
488 | ||
23c3a059 | 489 | template<typename _ValueType> |
52e86221 VV |
490 | inline _ValueType any_cast(any&& __any) |
491 | { | |
6791489e | 492 | using _Up = __remove_cvref_t<_ValueType>; |
52e86221 VV |
493 | static_assert(any::__is_valid_cast<_ValueType>(), |
494 | "Template argument must be a reference or CopyConstructible type"); | |
23c3a059 VV |
495 | static_assert(is_constructible_v<_ValueType, _Up>, |
496 | "Template argument must be constructible from an rvalue."); | |
497 | auto __p = any_cast<_Up>(&__any); | |
52e86221 | 498 | if (__p) |
62549523 | 499 | return static_cast<_ValueType>(std::move(*__p)); |
52e86221 VV |
500 | __throw_bad_any_cast(); |
501 | } | |
f0b88346 | 502 | /// @} |
52e86221 | 503 | |
aa573a6a | 504 | /// @cond undocumented |
52e86221 VV |
505 | template<typename _Tp> |
506 | void* __any_caster(const any* __any) | |
507 | { | |
92750002 JW |
508 | // any_cast<T> returns non-null if __any->type() == typeid(T) and |
509 | // typeid(T) ignores cv-qualifiers so remove them: | |
510 | using _Up = remove_cv_t<_Tp>; | |
511 | // The contained value has a decayed type, so if decay_t<U> is not U, | |
512 | // then it's not possible to have a contained value of type U: | |
513 | if constexpr (!is_same_v<decay_t<_Up>, _Up>) | |
514 | return nullptr; | |
515 | // Only copy constructible types can be used for contained values: | |
516 | else if constexpr (!is_copy_constructible_v<_Up>) | |
517 | return nullptr; | |
aa573a6a JW |
518 | // First try comparing function addresses, which works without RTTI |
519 | else if (__any->_M_manager == &any::_Manager<_Up>::_S_manage | |
520 | #if __cpp_rtti | |
521 | || __any->type() == typeid(_Tp) | |
522 | #endif | |
523 | ) | |
38a9e5a6 | 524 | { |
f6bb145c | 525 | return any::_Manager<_Up>::_S_access(__any->_M_storage); |
38a9e5a6 JW |
526 | } |
527 | return nullptr; | |
52e86221 | 528 | } |
aa573a6a | 529 | /// @endcond |
52e86221 VV |
530 | |
531 | /** | |
532 | * @brief Access the contained object. | |
533 | * | |
534 | * @tparam _ValueType The type of the contained object. | |
535 | * @param __any A pointer to the object to access. | |
536 | * @return The address of the contained object if <code> | |
537 | * __any != nullptr && __any.type() == typeid(_ValueType) | |
538 | * </code>, otherwise a null pointer. | |
539 | * | |
540 | * @{ | |
541 | */ | |
542 | template<typename _ValueType> | |
543 | inline const _ValueType* any_cast(const any* __any) noexcept | |
544 | { | |
f9bfdfa2 JW |
545 | if constexpr (is_object_v<_ValueType>) |
546 | if (__any) | |
547 | return static_cast<_ValueType*>(__any_caster<_ValueType>(__any)); | |
52e86221 VV |
548 | return nullptr; |
549 | } | |
550 | ||
551 | template<typename _ValueType> | |
552 | inline _ValueType* any_cast(any* __any) noexcept | |
553 | { | |
f9bfdfa2 JW |
554 | if constexpr (is_object_v<_ValueType>) |
555 | if (__any) | |
556 | return static_cast<_ValueType*>(__any_caster<_ValueType>(__any)); | |
52e86221 VV |
557 | return nullptr; |
558 | } | |
f0b88346 | 559 | /// @} |
52e86221 VV |
560 | |
561 | template<typename _Tp> | |
562 | void | |
563 | any::_Manager_internal<_Tp>:: | |
564 | _S_manage(_Op __which, const any* __any, _Arg* __arg) | |
565 | { | |
566 | // The contained object is in _M_storage._M_buffer | |
567 | auto __ptr = reinterpret_cast<const _Tp*>(&__any->_M_storage._M_buffer); | |
568 | switch (__which) | |
569 | { | |
570 | case _Op_access: | |
571 | __arg->_M_obj = const_cast<_Tp*>(__ptr); | |
572 | break; | |
573 | case _Op_get_type_info: | |
574 | #if __cpp_rtti | |
575 | __arg->_M_typeinfo = &typeid(_Tp); | |
576 | #endif | |
577 | break; | |
578 | case _Op_clone: | |
579 | ::new(&__arg->_M_any->_M_storage._M_buffer) _Tp(*__ptr); | |
580 | __arg->_M_any->_M_manager = __any->_M_manager; | |
581 | break; | |
582 | case _Op_destroy: | |
583 | __ptr->~_Tp(); | |
584 | break; | |
585 | case _Op_xfer: | |
1725d05d VV |
586 | ::new(&__arg->_M_any->_M_storage._M_buffer) _Tp |
587 | (std::move(*const_cast<_Tp*>(__ptr))); | |
52e86221 VV |
588 | __ptr->~_Tp(); |
589 | __arg->_M_any->_M_manager = __any->_M_manager; | |
590 | const_cast<any*>(__any)->_M_manager = nullptr; | |
591 | break; | |
592 | } | |
593 | } | |
594 | ||
595 | template<typename _Tp> | |
596 | void | |
597 | any::_Manager_external<_Tp>:: | |
598 | _S_manage(_Op __which, const any* __any, _Arg* __arg) | |
599 | { | |
600 | // The contained object is *_M_storage._M_ptr | |
601 | auto __ptr = static_cast<const _Tp*>(__any->_M_storage._M_ptr); | |
602 | switch (__which) | |
603 | { | |
604 | case _Op_access: | |
605 | __arg->_M_obj = const_cast<_Tp*>(__ptr); | |
606 | break; | |
607 | case _Op_get_type_info: | |
608 | #if __cpp_rtti | |
609 | __arg->_M_typeinfo = &typeid(_Tp); | |
610 | #endif | |
611 | break; | |
612 | case _Op_clone: | |
613 | __arg->_M_any->_M_storage._M_ptr = new _Tp(*__ptr); | |
614 | __arg->_M_any->_M_manager = __any->_M_manager; | |
615 | break; | |
616 | case _Op_destroy: | |
617 | delete __ptr; | |
618 | break; | |
619 | case _Op_xfer: | |
620 | __arg->_M_any->_M_storage._M_ptr = __any->_M_storage._M_ptr; | |
621 | __arg->_M_any->_M_manager = __any->_M_manager; | |
622 | const_cast<any*>(__any)->_M_manager = nullptr; | |
623 | break; | |
624 | } | |
625 | } | |
626 | ||
627 | /// @} | |
73ebece3 | 628 | |
10f26de9 JW |
629 | namespace __detail::__variant |
630 | { | |
631 | template<typename> struct _Never_valueless_alt; // see <variant> | |
632 | ||
633 | // Provide the strong exception-safety guarantee when emplacing an | |
634 | // any into a variant. | |
635 | template<> | |
636 | struct _Never_valueless_alt<std::any> | |
637 | : std::true_type | |
638 | { }; | |
639 | } // namespace __detail::__variant | |
640 | ||
52e86221 VV |
641 | _GLIBCXX_END_NAMESPACE_VERSION |
642 | } // namespace std | |
643 | ||
10f26de9 | 644 | #endif // C++17 |
52e86221 | 645 | #endif // _GLIBCXX_ANY |