1 // Experimental shared_ptr with array support -*- C++ -*- 2 3 // Copyright (C) 2015-2018 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 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 template<typename _Tp1, typename = _Compatible<_Tp1>> 141 shared_ptr(std::auto_ptr<_Tp1>&& __r) 142 : _Base_type(std::move(__r)) 143 { _M_enable_shared_from_this_with(static_cast<_Tp1*>(this->get())); } 144 #endif 145 146 template<typename _Tp1, typename _Del, 147 typename = _UniqCompatible<_Tp1, _Del>> 148 shared_ptr(unique_ptr<_Tp1, _Del>&& __r) 149 : _Base_type(std::move(__r)) 150 { 151 // XXX assume conversion from __r.get() to this->get() to __elem_t* 152 // is a round trip, which might not be true in all cases. 153 using __elem_t = typename unique_ptr<_Tp1, _Del>::element_type; 154 _M_enable_shared_from_this_with(static_cast<__elem_t*>(this->get())); 155 } 156 157 constexpr shared_ptr(nullptr_t __p) 158 : _Base_type(__p) { } 159 160 // C++14 §20.8.2.2 161 ~shared_ptr() = default; 162 163 // C++14 §20.8.2.3 164 shared_ptr& operator=(const shared_ptr&) noexcept = default; 165 166 template <typename _Tp1> 167 _Compatible<_Tp1, shared_ptr&> 168 operator=(const shared_ptr<_Tp1>& __r) noexcept 169 { 170 _Base_type::operator=(__r); 171 return *this; 172 } 173 174 shared_ptr& 175 operator=(shared_ptr&& __r) noexcept 176 { 177 _Base_type::operator=(std::move(__r)); 178 return *this; 179 } 180 181 template <typename _Tp1> 182 _Compatible<_Tp1, shared_ptr&> 183 operator=(shared_ptr<_Tp1>&& __r) noexcept 184 { 185 _Base_type::operator=(std::move(__r)); 186 return *this; 187 } 188 189 #if _GLIBCXX_USE_DEPRECATED 190 template<typename _Tp1> 191 _Compatible<_Tp1, shared_ptr&> 192 operator=(std::auto_ptr<_Tp1>&& __r) 193 { 194 __shared_ptr<_Tp>::operator=(std::move(__r)); 195 return *this; 196 } 197 #endif 198 199 template <typename _Tp1, typename _Del> 200 _UniqCompatible<_Tp1, _Del, shared_ptr&> 201 operator=(unique_ptr<_Tp1, _Del>&& __r) 202 { 203 _Base_type::operator=(std::move(__r)); 204 return *this; 205 } 206 207 // C++14 §20.8.2.2.4 208 // swap & reset 209 // 8.2.1.2 shared_ptr observers 210 // in __shared_ptr 211 212 private: 213 template<typename _Alloc, typename... _Args> 214 shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 215 _Args&&... __args) 216 : _Base_type(__tag, __a, std::forward<_Args>(__args)...) 217 { _M_enable_shared_from_this_with(this->get()); } 218 219 template<typename _Tp1, typename _Alloc, typename... _Args> 220 friend shared_ptr<_Tp1> 221 allocate_shared(const _Alloc& __a, _Args&&... __args); 222 223 shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t) 224 : _Base_type(__r, std::nothrow) { } 225 226 friend class weak_ptr<_Tp>; 227 228 template<typename _Yp> 229 using __esft_base_t = 230 decltype(__expt_enable_shared_from_this_base(std::declval<_Yp*>())); 231 232 // Detect an accessible and unambiguous enable_shared_from_this base. 233 template<typename _Yp, typename = void> 234 struct __has_esft_base 235 : false_type { }; 236 237 template<typename _Yp> 238 struct __has_esft_base<_Yp, __void_t<__esft_base_t<_Yp>>> 239 : __bool_constant<!is_array_v<_Tp>> { }; // ignore base for arrays 240 241 template<typename _Yp> 242 typename enable_if<__has_esft_base<_Yp>::value>::type 243 _M_enable_shared_from_this_with(const _Yp* __p) noexcept 244 { 245 if (auto __base = __expt_enable_shared_from_this_base(__p)) 246 { 247 __base->_M_weak_this 248 = shared_ptr<_Yp>(*this, const_cast<_Yp*>(__p)); 249 } 250 } 251 252 template<typename _Yp> 253 typename enable_if<!__has_esft_base<_Yp>::value>::type 254 _M_enable_shared_from_this_with(const _Yp*) noexcept 255 { } 256 }; 257 258 // C++14 §20.8.2.2.7 //DOING 259 template<typename _Tp1, typename _Tp2> 260 bool operator==(const shared_ptr<_Tp1>& __a, 261 const shared_ptr<_Tp2>& __b) noexcept 262 { return __a.get() == __b.get(); } 263 264 template<typename _Tp> 265 inline bool 266 operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 267 { return !__a; } 268 269 template<typename _Tp> 270 inline bool 271 operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 272 { return !__a; } 273 274 template<typename _Tp1, typename _Tp2> 275 inline bool 276 operator!=(const shared_ptr<_Tp1>& __a, 277 const shared_ptr<_Tp2>& __b) noexcept 278 { return __a.get() != __b.get(); } 279 280 template<typename _Tp> 281 inline bool 282 operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 283 { return (bool)__a; } 284 285 template<typename _Tp> 286 inline bool 287 operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 288 { return (bool)__a; } 289 290 template<typename _Tp1, typename _Tp2> 291 inline bool 292 operator<(const shared_ptr<_Tp1>& __a, 293 const shared_ptr<_Tp2>& __b) noexcept 294 { 295 using __elem_t1 = typename shared_ptr<_Tp1>::element_type; 296 using __elem_t2 = typename shared_ptr<_Tp2>::element_type; 297 using _CT = common_type_t<__elem_t1*, __elem_t2*>; 298 return std::less<_CT>()(__a.get(), __b.get()); 299 } 300 301 template<typename _Tp> 302 inline bool 303 operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 304 { 305 using __elem_t = typename shared_ptr<_Tp>::element_type; 306 return std::less<__elem_t*>()(__a.get(), nullptr); 307 } 308 309 template<typename _Tp> 310 inline bool 311 operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 312 { 313 using __elem_t = typename shared_ptr<_Tp>::element_type; 314 return std::less<__elem_t*>()(nullptr, __a.get()); 315 } 316 317 template<typename _Tp1, typename _Tp2> 318 inline bool 319 operator<=(const shared_ptr<_Tp1>& __a, 320 const shared_ptr<_Tp2>& __b) noexcept 321 { return !(__b < __a); } 322 323 template<typename _Tp> 324 inline bool 325 operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 326 { return !(nullptr < __a); } 327 328 template<typename _Tp> 329 inline bool 330 operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 331 { return !(__a < nullptr); } 332 333 template<typename _Tp1, typename _Tp2> 334 inline bool 335 operator>(const shared_ptr<_Tp1>& __a, 336 const shared_ptr<_Tp2>& __b) noexcept 337 { return (__b < __a); } 338 339 template<typename _Tp> 340 inline bool 341 operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 342 { 343 using __elem_t = typename shared_ptr<_Tp>::element_type; 344 return std::less<__elem_t*>()(nullptr, __a.get()); 345 } 346 347 template<typename _Tp> 348 inline bool 349 operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 350 { 351 using __elem_t = typename shared_ptr<_Tp>::element_type; 352 return std::less<__elem_t*>()(__a.get(), nullptr); 353 } 354 355 template<typename _Tp1, typename _Tp2> 356 inline bool 357 operator>=(const shared_ptr<_Tp1>& __a, 358 const shared_ptr<_Tp2>& __b) noexcept 359 { return !(__a < __b); } 360 361 template<typename _Tp> 362 inline bool 363 operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 364 { return !(__a < nullptr); } 365 366 template<typename _Tp> 367 inline bool 368 operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 369 { return !(nullptr < __a); } 370 371 // C++14 §20.8.2.2.8 372 template<typename _Tp> 373 inline void 374 swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept 375 { __a.swap(__b); } 376 377 // 8.2.1.3, shared_ptr casts 378 template<typename _Tp, typename _Tp1> 379 inline shared_ptr<_Tp> 380 static_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept 381 { 382 using __elem_t = typename shared_ptr<_Tp>::element_type; 383 return shared_ptr<_Tp>(__r, static_cast<__elem_t*>(__r.get())); 384 } 385 386 template<typename _Tp, typename _Tp1> 387 inline shared_ptr<_Tp> 388 dynamic_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept 389 { 390 using __elem_t = typename shared_ptr<_Tp>::element_type; 391 if (_Tp* __p = dynamic_cast<__elem_t*>(__r.get())) 392 return shared_ptr<_Tp>(__r, __p); 393 return shared_ptr<_Tp>(); 394 } 395 396 template<typename _Tp, typename _Tp1> 397 inline shared_ptr<_Tp> 398 const_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept 399 { 400 using __elem_t = typename shared_ptr<_Tp>::element_type; 401 return shared_ptr<_Tp>(__r, const_cast<__elem_t*>(__r.get())); 402 } 403 404 template<typename _Tp, typename _Tp1> 405 inline shared_ptr<_Tp> 406 reinterpret_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept 407 { 408 using __elem_t = typename shared_ptr<_Tp>::element_type; 409 return shared_ptr<_Tp>(__r, reinterpret_cast<__elem_t*>(__r.get())); 410 } 411 412 // C++14 §20.8.2.3 413 template<typename _Tp> 414 class weak_ptr : public __weak_ptr<_Tp> 415 { 416 template<typename _Tp1, typename _Res = void> 417 using _Compatible = enable_if_t<__sp_compatible_v<_Tp1, _Tp>, _Res>; 418 419 using _Base_type = __weak_ptr<_Tp>; 420 421 public: 422 constexpr weak_ptr() noexcept = default; 423 424 template<typename _Tp1, typename = _Compatible<_Tp1>> 425 weak_ptr(const shared_ptr<_Tp1>& __r) noexcept 426 : _Base_type(__r) { } 427 428 weak_ptr(const weak_ptr&) noexcept = default; 429 430 template<typename _Tp1, typename = _Compatible<_Tp1>> 431 weak_ptr(const weak_ptr<_Tp1>& __r) noexcept 432 : _Base_type(__r) { } 433 434 weak_ptr(weak_ptr&&) noexcept = default; 435 436 template<typename _Tp1, typename = _Compatible<_Tp1>> 437 weak_ptr(weak_ptr<_Tp1>&& __r) noexcept 438 : _Base_type(std::move(__r)) { } 439 440 weak_ptr& 441 operator=(const weak_ptr& __r) noexcept = default; 442 443 template<typename _Tp1> 444 _Compatible<_Tp1, weak_ptr&> 445 operator=(const weak_ptr<_Tp1>& __r) noexcept 446 { 447 this->_Base_type::operator=(__r); 448 return *this; 449 } 450 451 template<typename _Tp1> 452 _Compatible<_Tp1, weak_ptr&> 453 operator=(const shared_ptr<_Tp1>& __r) noexcept 454 { 455 this->_Base_type::operator=(__r); 456 return *this; 457 } 458 459 weak_ptr& 460 operator=(weak_ptr&& __r) noexcept = default; 461 462 template<typename _Tp1> 463 _Compatible<_Tp1, weak_ptr&> 464 operator=(weak_ptr<_Tp1>&& __r) noexcept 465 { 466 this->_Base_type::operator=(std::move(__r)); 467 return *this; 468 } 469 470 shared_ptr<_Tp> 471 lock() const noexcept 472 { return shared_ptr<_Tp>(*this, std::nothrow); } 473 474 friend class enable_shared_from_this<_Tp>; 475 }; 476 477 // C++14 §20.8.2.3.6 478 template<typename _Tp> 479 inline void 480 swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept 481 { __a.swap(__b); } 482 483 /// C++14 §20.8.2.2.10 484 template<typename _Del, typename _Tp> 485 inline _Del* 486 get_deleter(const shared_ptr<_Tp>& __p) noexcept 487 { return std::get_deleter<_Del>(__p); } 488 489 // C++14 §20.8.2.2.11 490 template<typename _Ch, typename _Tr, typename _Tp> 491 inline std::basic_ostream<_Ch, _Tr>& 492 operator<<(std::basic_ostream<_Ch, _Tr>& __os, const shared_ptr<_Tp>& __p) 493 { 494 __os << __p.get(); 495 return __os; 496 } 497 498 // C++14 §20.8.2.4 499 template<typename _Tp = void> class owner_less; 500 501 /// Partial specialization of owner_less for shared_ptr. 502 template<typename _Tp> 503 struct owner_less<shared_ptr<_Tp>> 504 : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>> 505 { }; 506 507 /// Partial specialization of owner_less for weak_ptr. 508 template<typename _Tp> 509 struct owner_less<weak_ptr<_Tp>> 510 : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>> 511 { }; 512 513 template<> 514 class owner_less<void> 515 { 516 template<typename _Tp, typename _Up> 517 bool 518 operator()(shared_ptr<_Tp> const& __lhs, 519 shared_ptr<_Up> const& __rhs) const 520 { return __lhs.owner_before(__rhs); } 521 522 template<typename _Tp, typename _Up> 523 bool 524 operator()(shared_ptr<_Tp> const& __lhs, 525 weak_ptr<_Up> const& __rhs) const 526 { return __lhs.owner_before(__rhs); } 527 528 template<typename _Tp, typename _Up> 529 bool 530 operator()(weak_ptr<_Tp> const& __lhs, 531 shared_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 weak_ptr<_Up> const& __rhs) const 538 { return __lhs.owner_before(__rhs); } 539 540 typedef void is_transparent; 541 }; 542 543 // C++14 §20.8.2.6 544 template<typename _Tp> 545 inline bool 546 atomic_is_lock_free(const shared_ptr<_Tp>* __p) 547 { return std::atomic_is_lock_free<_Tp, __default_lock_policy>(__p); } 548 549 template<typename _Tp> 550 shared_ptr<_Tp> atomic_load(const shared_ptr<_Tp>* __p) 551 { return std::atomic_load<_Tp>(__p); } 552 553 template<typename _Tp> 554 shared_ptr<_Tp> 555 atomic_load_explicit(const shared_ptr<_Tp>* __p, memory_order __mo) 556 { return std::atomic_load_explicit<_Tp>(__p, __mo); } 557 558 template<typename _Tp> 559 void atomic_store(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r) 560 { return std::atomic_store<_Tp>(__p, __r); } 561 562 template<typename _Tp> 563 shared_ptr<_Tp> 564 atomic_store_explicit(const shared_ptr<_Tp>* __p, 565 shared_ptr<_Tp> __r, 566 memory_order __mo) 567 { return std::atomic_store_explicit<_Tp>(__p, __r, __mo); } 568 569 template<typename _Tp> 570 void atomic_exchange(shared_ptr<_Tp>* __p, shared_ptr<_Tp> __r) 571 { return std::atomic_exchange<_Tp>(__p, __r); } 572 573 template<typename _Tp> 574 shared_ptr<_Tp> 575 atomic_exchange_explicit(const shared_ptr<_Tp>* __p, 576 shared_ptr<_Tp> __r, 577 memory_order __mo) 578 { return std::atomic_exchange_explicit<_Tp>(__p, __r, __mo); } 579 580 template<typename _Tp> 581 bool atomic_compare_exchange_weak(shared_ptr<_Tp>* __p, 582 shared_ptr<_Tp>* __v, 583 shared_ptr<_Tp> __w) 584 { return std::atomic_compare_exchange_weak<_Tp>(__p, __v, __w); } 585 586 template<typename _Tp> 587 bool atomic_compare_exchange_strong(shared_ptr<_Tp>* __p, 588 shared_ptr<_Tp>* __v, 589 shared_ptr<_Tp> __w) 590 { return std::atomic_compare_exchange_strong<_Tp>(__p, __v, __w); } 591 592 template<typename _Tp> 593 bool atomic_compare_exchange_weak_explicit(shared_ptr<_Tp>* __p, 594 shared_ptr<_Tp>* __v, 595 shared_ptr<_Tp> __w, 596 memory_order __success, 597 memory_order __failure) 598 { return std::atomic_compare_exchange_weak_explicit<_Tp>(__p, __v, __w, 599 __success, 600 __failure); } 601 602 template<typename _Tp> 603 bool atomic_compare_exchange_strong_explicit(shared_ptr<_Tp>* __p, 604 shared_ptr<_Tp>* __v, 605 shared_ptr<_Tp> __w, 606 memory_order __success, 607 memory_order __failure) 608 { return std::atomic_compare_exchange_strong_explicit<_Tp>(__p, __v, __w, 609 __success, 610 __failure); } 611 612 //enable_shared_from_this 613 template<typename _Tp> 614 class enable_shared_from_this 615 { 616 protected: 617 constexpr enable_shared_from_this() noexcept { } 618 619 enable_shared_from_this(const enable_shared_from_this&) noexcept { } 620 621 enable_shared_from_this& 622 operator=(const enable_shared_from_this&) noexcept 623 { return *this; } 624 625 ~enable_shared_from_this() { } 626 627 public: 628 shared_ptr<_Tp> 629 shared_from_this() 630 { return shared_ptr<_Tp>(this->_M_weak_this); } 631 632 shared_ptr<const _Tp> 633 shared_from_this() const 634 { return shared_ptr<const _Tp>(this->_M_weak_this); } 635 636 weak_ptr<_Tp> 637 weak_from_this() noexcept 638 { return _M_weak_this; } 639 640 weak_ptr<const _Tp> 641 weak_from_this() const noexcept 642 { return _M_weak_this; } 643 644 private: 645 template<typename _Tp1> 646 void 647 _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept 648 { _M_weak_this._M_assign(__p, __n); } 649 650 // Found by ADL when this is an associated class. 651 friend const enable_shared_from_this* 652 __expt_enable_shared_from_this_base(const enable_shared_from_this* __p) 653 { return __p; } 654 655 template<typename> 656 friend class shared_ptr; 657 658 mutable weak_ptr<_Tp> _M_weak_this; 659 }; 660 } // namespace fundamentals_v2 661 } // namespace experimental 662 663 /// std::hash specialization for shared_ptr. 664 template<typename _Tp> 665 struct hash<experimental::shared_ptr<_Tp>> 666 : public __hash_base<size_t, experimental::shared_ptr<_Tp>> 667 { 668 size_t 669 operator()(const experimental::shared_ptr<_Tp>& __s) const noexcept 670 { return std::hash<_Tp*>()(__s.get()); } 671 }; 672 673 _GLIBCXX_END_NAMESPACE_VERSION 674 } // namespace std 675 676 #endif // __cplusplus <= 201103L 677 678 #endif // _GLIBCXX_EXPERIMENTAL_SHARED_PTR_H 679