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/usr/include/c++/13/experimental/bits/shared_ptr.h
$ cat -n /usr/include/c++/13/experimental/bits/shared_ptr.h 1 // Experimental shared_ptr with array support -*- C++ -*- 2 3 // Copyright (C) 2015-2023 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 experimental/bits/shared_ptr.h 26 * This is an internal header file, included by other library headers. 27 * Do not attempt to use it directly. @headername{experimental/memory} 28 */ 29 30 #ifndef _GLIBCXX_EXPERIMENTAL_SHARED_PTR_H 31 #define _GLIBCXX_EXPERIMENTAL_SHARED_PTR_H 1 32 33 #pragma GCC system_header 34 35 #if __cplusplus >= 201402L 36 37 #include <memory> 38 #include <experimental/type_traits> 39 40 namespace std _GLIBCXX_VISIBILITY(default) 41 { 42 _GLIBCXX_BEGIN_NAMESPACE_VERSION 43 44 namespace experimental 45 { 46 inline namespace fundamentals_v2 47 { 48 // 8.2.1 49 50 template<typename _Tp> class shared_ptr; 51 template<typename _Tp> class weak_ptr; 52 template<typename _Tp> class enable_shared_from_this; 53 54 template<typename _Yp, typename _Tp> 55 constexpr bool __sp_compatible_v 56 = std::__sp_compatible_with<_Yp*, _Tp*>::value; 57 58 template<typename _Tp, typename _Yp> 59 constexpr bool __sp_is_constructible_v 60 = std::__sp_is_constructible<_Tp, _Yp>::value; 61 62 template<typename _Tp> 63 class shared_ptr : public __shared_ptr<_Tp> 64 { 65 using _Base_type = __shared_ptr<_Tp>; 66 67 public: 68 using element_type = typename _Base_type::element_type; 69 70 private: 71 // Constraint for construction from a pointer of type _Yp*: 72 template<typename _Yp> 73 using _SafeConv = enable_if_t<__sp_is_constructible_v<_Tp, _Yp>>; 74 75 template<typename _Tp1, typename _Res = void> 76 using _Compatible 77 = enable_if_t<__sp_compatible_v<_Tp1, _Tp>, _Res>; 78 79 template<typename _Tp1, typename _Del, 80 typename _Ptr = typename unique_ptr<_Tp1, _Del>::pointer, 81 typename _Res = void> 82 using _UniqCompatible = enable_if_t< 83 __sp_compatible_v<_Tp1, _Tp> 84 && experimental::is_convertible_v<_Ptr, element_type*>, 85 _Res>; 86 87 public: 88 89 // 8.2.1.1, shared_ptr constructors 90 constexpr shared_ptr() noexcept = default; 91 92 template<typename _Tp1, typename = _SafeConv<_Tp1>> 93 explicit 94 shared_ptr(_Tp1* __p) : _Base_type(__p) 95 { _M_enable_shared_from_this_with(__p); } 96 97 template<typename _Tp1, typename _Deleter, typename = _SafeConv<_Tp1>> 98 shared_ptr(_Tp1* __p, _Deleter __d) 99 : _Base_type(__p, __d) 100 { _M_enable_shared_from_this_with(__p); } 101 102 template<typename _Tp1, typename _Deleter, typename _Alloc, 103 typename = _SafeConv<_Tp1>> 104 shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a) 105 : _Base_type(__p, __d, __a) 106 { _M_enable_shared_from_this_with(__p); } 107 108 template<typename _Deleter> 109 shared_ptr(nullptr_t __p, _Deleter __d) 110 : _Base_type(__p, __d) { } 111 112 template<typename _Deleter, typename _Alloc> 113 shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) 114 : _Base_type(__p, __d, __a) { } 115 116 template<typename _Tp1> 117 shared_ptr(const shared_ptr<_Tp1>& __r, element_type* __p) noexcept 118 : _Base_type(__r, __p) { } 119 120 shared_ptr(const shared_ptr& __r) noexcept 121 : _Base_type(__r) { } 122 123 template<typename _Tp1, typename = _Compatible<_Tp1>> 124 shared_ptr(const shared_ptr<_Tp1>& __r) noexcept 125 : _Base_type(__r) { } 126 127 shared_ptr(shared_ptr&& __r) noexcept 128 : _Base_type(std::move(__r)) { } 129 130 template<typename _Tp1, typename = _Compatible<_Tp1>> 131 shared_ptr(shared_ptr<_Tp1>&& __r) noexcept 132 : _Base_type(std::move(__r)) { } 133 134 template<typename _Tp1, typename = _Compatible<_Tp1>> 135 explicit 136 shared_ptr(const weak_ptr<_Tp1>& __r) 137 : _Base_type(__r) { } 138 139 #if _GLIBCXX_USE_DEPRECATED 140 #pragma GCC diagnostic push 141 #pragma GCC diagnostic ignored "-Wdeprecated-declarations" 142 template<typename _Tp1, typename = _Compatible<_Tp1>> 143 shared_ptr(std::auto_ptr<_Tp1>&& __r) 144 : _Base_type(std::move(__r)) 145 { _M_enable_shared_from_this_with(static_cast<_Tp1*>(this->get())); } 146 #pragma GCC diagnostic pop 147 #endif 148 149 template<typename _Tp1, typename _Del, 150 typename = _UniqCompatible<_Tp1, _Del>> 151 shared_ptr(unique_ptr<_Tp1, _Del>&& __r) 152 : _Base_type(std::move(__r)) 153 { 154 // XXX assume conversion from __r.get() to this->get() to __elem_t* 155 // is a round trip, which might not be true in all cases. 156 using __elem_t = typename unique_ptr<_Tp1, _Del>::element_type; 157 _M_enable_shared_from_this_with(static_cast<__elem_t*>(this->get())); 158 } 159 160 constexpr shared_ptr(nullptr_t __p) 161 : _Base_type(__p) { } 162 163 // C++14 20.8.2.2 164 ~shared_ptr() = default; 165 166 // C++14 20.8.2.3 167 shared_ptr& operator=(const shared_ptr&) noexcept = default; 168 169 template <typename _Tp1> 170 _Compatible<_Tp1, shared_ptr&> 171 operator=(const shared_ptr<_Tp1>& __r) noexcept 172 { 173 _Base_type::operator=(__r); 174 return *this; 175 } 176 177 shared_ptr& 178 operator=(shared_ptr&& __r) noexcept 179 { 180 _Base_type::operator=(std::move(__r)); 181 return *this; 182 } 183 184 template <typename _Tp1> 185 _Compatible<_Tp1, shared_ptr&> 186 operator=(shared_ptr<_Tp1>&& __r) noexcept 187 { 188 _Base_type::operator=(std::move(__r)); 189 return *this; 190 } 191 192 #if _GLIBCXX_USE_DEPRECATED 193 #pragma GCC diagnostic push 194 #pragma GCC diagnostic ignored "-Wdeprecated-declarations" 195 template<typename _Tp1> 196 _Compatible<_Tp1, shared_ptr&> 197 operator=(std::auto_ptr<_Tp1>&& __r) 198 { 199 __shared_ptr<_Tp>::operator=(std::move(__r)); 200 return *this; 201 } 202 #pragma GCC diagnostic pop 203 #endif 204 205 template <typename _Tp1, typename _Del> 206 _UniqCompatible<_Tp1, _Del, shared_ptr&> 207 operator=(unique_ptr<_Tp1, _Del>&& __r) 208 { 209 _Base_type::operator=(std::move(__r)); 210 return *this; 211 } 212 213 // C++14 20.8.2.2.4 214 // swap & reset 215 // 8.2.1.2 shared_ptr observers 216 // in __shared_ptr 217 218 private: 219 template<typename _Alloc, typename... _Args> 220 shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 221 _Args&&... __args) 222 : _Base_type(__tag, __a, std::forward<_Args>(__args)...) 223 { _M_enable_shared_from_this_with(this->get()); } 224 225 template<typename _Tp1, typename _Alloc, typename... _Args> 226 friend shared_ptr<_Tp1> 227 allocate_shared(const _Alloc& __a, _Args&&... __args); 228 229 shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t) 230 : _Base_type(__r, std::nothrow) { } 231 232 friend class weak_ptr<_Tp>; 233 234 template<typename _Yp> 235 using __esft_base_t = 236 decltype(__expt_enable_shared_from_this_base(std::declval<_Yp*>())); 237 238 // Detect an accessible and unambiguous enable_shared_from_this base. 239 template<typename _Yp, typename = void> 240 struct __has_esft_base 241 : false_type { }; 242 243 template<typename _Yp> 244 struct __has_esft_base<_Yp, __void_t<__esft_base_t<_Yp>>> 245 : __bool_constant<!is_array_v<_Tp>> { }; // ignore base for arrays 246 247 template<typename _Yp> 248 typename enable_if<__has_esft_base<_Yp>::value>::type 249 _M_enable_shared_from_this_with(const _Yp* __p) noexcept 250 { 251 if (auto __base = __expt_enable_shared_from_this_base(__p)) 252 { 253 __base->_M_weak_this 254 = shared_ptr<_Yp>(*this, const_cast<_Yp*>(__p)); 255 } 256 } 257 258 template<typename _Yp> 259 typename enable_if<!__has_esft_base<_Yp>::value>::type 260 _M_enable_shared_from_this_with(const _Yp*) noexcept 261 { } 262 }; 263 264 // C++14 20.8.2.2.7 265 template<typename _Tp1, typename _Tp2> 266 bool operator==(const shared_ptr<_Tp1>& __a, 267 const shared_ptr<_Tp2>& __b) noexcept 268 { return __a.get() == __b.get(); } 269 270 template<typename _Tp> 271 inline bool 272 operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 273 { return !__a; } 274 275 template<typename _Tp> 276 inline bool 277 operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 278 { return !__a; } 279 280 template<typename _Tp1, typename _Tp2> 281 inline bool 282 operator!=(const shared_ptr<_Tp1>& __a, 283 const shared_ptr<_Tp2>& __b) noexcept 284 { return __a.get() != __b.get(); } 285 286 template<typename _Tp> 287 inline bool 288 operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 289 { return (bool)__a; } 290 291 template<typename _Tp> 292 inline bool 293 operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 294 { return (bool)__a; } 295 296 template<typename _Tp1, typename _Tp2> 297 inline bool 298 operator<(const shared_ptr<_Tp1>& __a, 299 const shared_ptr<_Tp2>& __b) noexcept 300 { 301 using __elem_t1 = typename shared_ptr<_Tp1>::element_type; 302 using __elem_t2 = typename shared_ptr<_Tp2>::element_type; 303 using _CT = common_type_t<__elem_t1*, __elem_t2*>; 304 return std::less<_CT>()(__a.get(), __b.get()); 305 } 306 307 template<typename _Tp> 308 inline bool 309 operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 310 { 311 using __elem_t = typename shared_ptr<_Tp>::element_type; 312 return std::less<__elem_t*>()(__a.get(), nullptr); 313 } 314 315 template<typename _Tp> 316 inline bool 317 operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 318 { 319 using __elem_t = typename shared_ptr<_Tp>::element_type; 320 return std::less<__elem_t*>()(nullptr, __a.get()); 321 } 322 323 template<typename _Tp1, typename _Tp2> 324 inline bool 325 operator<=(const shared_ptr<_Tp1>& __a, 326 const shared_ptr<_Tp2>& __b) noexcept 327 { return !(__b < __a); } 328 329 template<typename _Tp> 330 inline bool 331 operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 332 { return !(nullptr < __a); } 333 334 template<typename _Tp> 335 inline bool 336 operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 337 { return !(__a < nullptr); } 338 339 template<typename _Tp1, typename _Tp2> 340 inline bool 341 operator>(const shared_ptr<_Tp1>& __a, 342 const shared_ptr<_Tp2>& __b) noexcept 343 { return (__b < __a); } 344 345 template<typename _Tp> 346 inline bool 347 operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 348 { 349 using __elem_t = typename shared_ptr<_Tp>::element_type; 350 return std::less<__elem_t*>()(nullptr, __a.get()); 351 } 352 353 template<typename _Tp> 354 inline bool 355 operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 356 { 357 using __elem_t = typename shared_ptr<_Tp>::element_type; 358 return std::less<__elem_t*>()(__a.get(), nullptr); 359 } 360 361 template<typename _Tp1, typename _Tp2> 362 inline bool 363 operator>=(const shared_ptr<_Tp1>& __a, 364 const shared_ptr<_Tp2>& __b) noexcept 365 { return !(__a < __b); } 366 367 template<typename _Tp> 368 inline bool 369 operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 370 { return !(__a < nullptr); } 371 372 template<typename _Tp> 373 inline bool 374 operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 375 { return !(nullptr < __a); } 376 377 // C++14 20.8.2.2.8 378 template<typename _Tp> 379 inline void 380 swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept 381 { __a.swap(__b); } 382 383 // 8.2.1.3, shared_ptr casts 384 template<typename _Tp, typename _Tp1> 385 inline shared_ptr<_Tp> 386 static_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept 387 { 388 using __elem_t = typename shared_ptr<_Tp>::element_type; 389 return shared_ptr<_Tp>(__r, static_cast<__elem_t*>(__r.get())); 390 } 391 392 template<typename _Tp, typename _Tp1> 393 inline shared_ptr<_Tp> 394 dynamic_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept 395 { 396 using __elem_t = typename shared_ptr<_Tp>::element_type; 397 if (_Tp* __p = dynamic_cast<__elem_t*>(__r.get())) 398 return shared_ptr<_Tp>(__r, __p); 399 return shared_ptr<_Tp>(); 400 } 401 402 template<typename _Tp, typename _Tp1> 403 inline shared_ptr<_Tp> 404 const_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept 405 { 406 using __elem_t = typename shared_ptr<_Tp>::element_type; 407 return shared_ptr<_Tp>(__r, const_cast<__elem_t*>(__r.get())); 408 } 409 410 template<typename _Tp, typename _Tp1> 411 inline shared_ptr<_Tp> 412 reinterpret_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept 413 { 414 using __elem_t = typename shared_ptr<_Tp>::element_type; 415 return shared_ptr<_Tp>(__r, reinterpret_cast<__elem_t*>(__r.get())); 416 } 417 418 // C++14 20.8.2.3 419 template<typename _Tp> 420 class weak_ptr : public __weak_ptr<_Tp> 421 { 422 template<typename _Tp1, typename _Res = void> 423 using _Compatible = enable_if_t<__sp_compatible_v<_Tp1, _Tp>, _Res>; 424 425 using _Base_type = __weak_ptr<_Tp>; 426 427 public: 428 constexpr weak_ptr() noexcept = default; 429 430 template<typename _Tp1, typename = _Compatible<_Tp1>> 431 weak_ptr(const shared_ptr<_Tp1>& __r) noexcept 432 : _Base_type(__r) { } 433 434 weak_ptr(const weak_ptr&) noexcept = default; 435 436 template<typename _Tp1, typename = _Compatible<_Tp1>> 437 weak_ptr(const weak_ptr<_Tp1>& __r) noexcept 438 : _Base_type(__r) { } 439 440 weak_ptr(weak_ptr&&) noexcept = default; 441 442 template<typename _Tp1, typename = _Compatible<_Tp1>> 443 weak_ptr(weak_ptr<_Tp1>&& __r) noexcept 444 : _Base_type(std::move(__r)) { } 445 446 weak_ptr& 447 operator=(const weak_ptr& __r) noexcept = default; 448 449 template<typename _Tp1> 450 _Compatible<_Tp1, weak_ptr&> 451 operator=(const weak_ptr<_Tp1>& __r) noexcept 452 { 453 this->_Base_type::operator=(__r); 454 return *this; 455 } 456 457 template<typename _Tp1> 458 _Compatible<_Tp1, weak_ptr&> 459 operator=(const shared_ptr<_Tp1>& __r) noexcept 460 { 461 this->_Base_type::operator=(__r); 462 return *this; 463 } 464 465 weak_ptr& 466 operator=(weak_ptr&& __r) noexcept = default; 467 468 template<typename _Tp1> 469 _Compatible<_Tp1, weak_ptr&> 470 operator=(weak_ptr<_Tp1>&& __r) noexcept 471 { 472 this->_Base_type::operator=(std::move(__r)); 473 return *this; 474 } 475 476 shared_ptr<_Tp> 477 lock() const noexcept 478 { return shared_ptr<_Tp>(*this, std::nothrow); } 479 480 friend class enable_shared_from_this<_Tp>; 481 }; 482 483 // C++14 20.8.2.3.6 484 template<typename _Tp> 485 inline void 486 swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept 487 { __a.swap(__b); } 488 489 /// C++14 20.8.2.2.10 490 template<typename _Del, typename _Tp> 491 inline _Del* 492 get_deleter(const shared_ptr<_Tp>& __p) noexcept 493 { return std::get_deleter<_Del>(__p); } 494 495 // C++14 20.8.2.2.11 496 template<typename _Ch, typename _Tr, typename _Tp> 497 inline std::basic_ostream<_Ch, _Tr>& 498 operator<<(std::basic_ostream<_Ch, _Tr>& __os, const shared_ptr<_Tp>& __p) 499 { 500 __os << __p.get(); 501 return __os; 502 } 503 504 // C++14 20.8.2.4 505 template<typename _Tp = void> class owner_less; 506 507 /// Partial specialization of owner_less for shared_ptr. 508 template<typename _Tp> 509 struct owner_less<shared_ptr<_Tp>> 510 : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>> 511 { }; 512 513 /// Partial specialization of owner_less for weak_ptr. 514 template<typename _Tp> 515 struct owner_less<weak_ptr<_Tp>> 516 : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>> 517 { }; 518 519 template<> 520 class owner_less<void> 521 { 522 template<typename _Tp, typename _Up> 523 bool 524 operator()(shared_ptr<_Tp> const& __lhs, 525 shared_ptr<_Up> const& __rhs) const 526 { return __lhs.owner_before(__rhs); } 527 528 template<typename _Tp, typename _Up> 529 bool 530 operator()(shared_ptr<_Tp> const& __lhs, 531 weak_ptr<_Up> const& __rhs) const 532 { return __lhs.owner_before(__rhs); } 533 534 template<typename _Tp, typename _Up> 535 bool 536 operator()(weak_ptr<_Tp> const& __lhs, 537 shared_ptr<_Up> const& __rhs) const 538 { return __lhs.owner_before(__rhs); } 539 540 template<typename _Tp, typename _Up> 541 bool 542 operator()(weak_ptr<_Tp> const& __lhs, 543 weak_ptr<_Up> const& __rhs) const 544 { return __lhs.owner_before(__rhs); } 545 546 typedef void is_transparent; 547 }; 548 549 // C++14 20.8.2.6 550 template<typename _Tp> 551 inline bool 552 atomic_is_lock_free(const shared_ptr<_Tp>* __p) 553 { return std::atomic_is_lock_free<_Tp, __default_lock_policy>(__p); } 554 555 template<typename _Tp> 556 shared_ptr<_Tp> atomic_load(const shared_ptr<_Tp>* __p) 557 { return std::atomic_load<_Tp>(__p); } 558 559 template<typename _Tp> 560 shared_ptr<_Tp> 561 atomic_load_explicit(const shared_ptr<_Tp>* __p, memory_order __mo) 562 { return std::atomic_load_explicit<_Tp>(__p, __mo); } 563 564 template<typename _Tp> 565 void atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r) 566 { return std::atomic_store<_Tp>(__p, __r); } 567 568 template<typename _Tp> 569 shared_ptr<_Tp> 570 atomic_store_explicit(const shared_ptr<_Tp>* __p, 571 shared_ptr<_Tp> __r, 572 memory_order __mo) 573 { return std::atomic_store_explicit<_Tp>(__p, __r, __mo); } 574 575 template<typename _Tp> 576 void atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r) 577 { return std::atomic_exchange<_Tp>(__p, __r); } 578 579 template<typename _Tp> 580 shared_ptr<_Tp> 581 atomic_exchange_explicit(const shared_ptr<_Tp>* __p, 582 shared_ptr<_Tp> __r, 583 memory_order __mo) 584 { return std::atomic_exchange_explicit<_Tp>(__p, __r, __mo); } 585 586 template<typename _Tp> 587 bool atomic_compare_exchange_weak(shared_ptr<_Tp>* __p, 588 shared_ptr<_Tp>* __v, 589 shared_ptr<_Tp> __w) 590 { return std::atomic_compare_exchange_weak<_Tp>(__p, __v, __w); } 591 592 template<typename _Tp> 593 bool atomic_compare_exchange_strong(shared_ptr<_Tp>* __p, 594 shared_ptr<_Tp>* __v, 595 shared_ptr<_Tp> __w) 596 { return std::atomic_compare_exchange_strong<_Tp>(__p, __v, __w); } 597 598 template<typename _Tp> 599 bool atomic_compare_exchange_weak_explicit(shared_ptr<_Tp>* __p, 600 shared_ptr<_Tp>* __v, 601 shared_ptr<_Tp> __w, 602 memory_order __success, 603 memory_order __failure) 604 { return std::atomic_compare_exchange_weak_explicit<_Tp>(__p, __v, __w, 605 __success, 606 __failure); } 607 608 template<typename _Tp> 609 bool atomic_compare_exchange_strong_explicit(shared_ptr<_Tp>* __p, 610 shared_ptr<_Tp>* __v, 611 shared_ptr<_Tp> __w, 612 memory_order __success, 613 memory_order __failure) 614 { return std::atomic_compare_exchange_strong_explicit<_Tp>(__p, __v, __w, 615 __success, 616 __failure); } 617 618 //enable_shared_from_this 619 template<typename _Tp> 620 class enable_shared_from_this 621 { 622 protected: 623 constexpr enable_shared_from_this() noexcept { } 624 625 enable_shared_from_this(const enable_shared_from_this&) noexcept { } 626 627 enable_shared_from_this& 628 operator=(const enable_shared_from_this&) noexcept 629 { return *this; } 630 631 ~enable_shared_from_this() { } 632 633 public: 634 shared_ptr<_Tp> 635 shared_from_this() 636 { return shared_ptr<_Tp>(this->_M_weak_this); } 637 638 shared_ptr<const _Tp> 639 shared_from_this() const 640 { return shared_ptr<const _Tp>(this->_M_weak_this); } 641 642 weak_ptr<_Tp> 643 weak_from_this() noexcept 644 { return _M_weak_this; } 645 646 weak_ptr<const _Tp> 647 weak_from_this() const noexcept 648 { return _M_weak_this; } 649 650 private: 651 template<typename _Tp1> 652 void 653 _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept 654 { _M_weak_this._M_assign(__p, __n); } 655 656 // Found by ADL when this is an associated class. 657 friend const enable_shared_from_this* 658 __expt_enable_shared_from_this_base(const enable_shared_from_this* __p) 659 { return __p; } 660 661 template<typename> 662 friend class shared_ptr; 663 664 mutable weak_ptr<_Tp> _M_weak_this; 665 }; 666 } // namespace fundamentals_v2 667 } // namespace experimental 668 669 /// std::hash specialization for shared_ptr. 670 template<typename _Tp> 671 struct hash<experimental::shared_ptr<_Tp>> 672 : public __hash_base<size_t, experimental::shared_ptr<_Tp>> 673 { 674 size_t 675 operator()(const experimental::shared_ptr<_Tp>& __s) const noexcept 676 { return std::hash<_Tp*>()(__s.get()); } 677 }; 678 679 _GLIBCXX_END_NAMESPACE_VERSION 680 } // namespace std 681 682 #endif // __cplusplus <= 201103L 683 684 #endif // _GLIBCXX_EXPERIMENTAL_SHARED_PTR_H
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