libstdc++-v3/include/debug/forward_list

   1 // <forward_list> -*- C++ -*-
   2
   3 // Copyright (C) 2010-2020 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 debug/forward_list
  26  *  This file is a GNU debug extension to the Standard C++ Library.
  27  */
  28
  29 #ifndef _GLIBCXX_DEBUG_FORWARD_LIST
  30 #define _GLIBCXX_DEBUG_FORWARD_LIST 1
  31
  32 #pragma GCC system_header
  33
  34 #include <bits/c++config.h>
  35 namespace std _GLIBCXX_VISIBILITY(default) { namespace __debug {
  36   template<typename _Tp, typename _Allocator> class forward_list;
  37 } } // namespace std::__debug
  38
  39 #include <forward_list>
  40 #include <debug/safe_sequence.h>
  41 #include <debug/safe_container.h>
  42 #include <debug/safe_iterator.h>
  43
  44 // Special validity check for forward_list ranges.
  45 #define __glibcxx_check_valid_fl_range(_First,_Last,_Dist)              \
  46 _GLIBCXX_DEBUG_VERIFY(_First._M_valid_range(_Last, _Dist, false),       \
  47                       _M_message(__gnu_debug::__msg_valid_range)        \
  48                       ._M_iterator(_First, #_First)                     \
  49                       ._M_iterator(_Last, #_Last))
  50
  51 namespace __gnu_debug
  52 {
  53   /// Special iterators swap and invalidation for forward_list because of the
  54   /// before_begin iterator.
  55   template<typename _SafeSequence>
  56     class _Safe_forward_list
  57     : public _Safe_sequence<_SafeSequence>
  58     {
  59       _SafeSequence&
  60       _M_this() noexcept
  61       { return *static_cast<_SafeSequence*>(this); }
  62
  63       static void
  64       _M_swap_aux(_Safe_sequence_base& __lhs,
  65                   _Safe_iterator_base*& __lhs_iterators,
  66                   _Safe_sequence_base& __rhs,
  67                   _Safe_iterator_base*& __rhs_iterators);
  68
  69       void _M_swap_single(_Safe_sequence_base&) noexcept;
  70
  71     protected:
  72       void
  73       _M_invalidate_all()
  74       {
  75         using _Base_const_iterator = __decltype(_M_this()._M_base().cend());
  76         this->_M_invalidate_if([this](_Base_const_iterator __it)
  77         {
  78           return __it != _M_this()._M_base().cbefore_begin()
  79             && __it != _M_this()._M_base().cend(); });
  80       }
  81
  82       void _M_swap(_Safe_sequence_base&) noexcept;
  83     };
  84
  85    template<typename _SafeSequence>
  86     void
  87     _Safe_forward_list<_SafeSequence>::
  88     _M_swap_aux(_Safe_sequence_base& __lhs,
  89                 _Safe_iterator_base*& __lhs_iterators,
  90                 _Safe_sequence_base& __rhs,
  91                 _Safe_iterator_base*& __rhs_iterators)
  92     {
  93       using const_iterator = typename _SafeSequence::const_iterator;
  94       _Safe_iterator_base* __bbegin_its = 0;
  95       _Safe_iterator_base* __last_bbegin = 0;
  96       _SafeSequence& __rseq = static_cast<_SafeSequence&>(__rhs);
  97
  98       for (_Safe_iterator_base* __iter = __lhs_iterators; __iter;)
  99         {
 100           // Even iterator is cast to const_iterator, not a problem.
 101           _Safe_iterator_base* __victim_base = __iter;
 102           const_iterator* __victim =
 103             static_cast<const_iterator*>(__victim_base);
 104           __iter = __iter->_M_next;
 105           if (__victim->base() == __rseq._M_base().cbefore_begin())
 106             {
 107               __victim->_M_unlink();
 108               if (__lhs_iterators == __victim_base)
 109                 __lhs_iterators = __victim_base->_M_next;
 110               if (__bbegin_its)
 111                 {
 112                   __victim_base->_M_next = __bbegin_its;
 113                   __bbegin_its->_M_prior = __victim_base;
 114                 }
 115               else
 116                 __last_bbegin = __victim_base;
 117               __bbegin_its = __victim_base;
 118             }
 119           else
 120             __victim_base->_M_sequence = std::__addressof(__lhs);
 121         }
 122
 123       if (__bbegin_its)
 124         {
 125           if (__rhs_iterators)
 126             {
 127               __rhs_iterators->_M_prior = __last_bbegin;
 128               __last_bbegin->_M_next = __rhs_iterators;
 129             }
 130           __rhs_iterators = __bbegin_its;
 131         }
 132     }
 133
 134    template<typename _SafeSequence>
 135     void
 136     _Safe_forward_list<_SafeSequence>::
 137     _M_swap_single(_Safe_sequence_base& __other) noexcept
 138     {
 139       std::swap(_M_this()._M_iterators, __other._M_iterators);
 140       std::swap(_M_this()._M_const_iterators, __other._M_const_iterators);
 141       // Useless, always 1 on forward_list
 142       //std::swap(_M_this()_M_version, __other._M_version);
 143       _Safe_iterator_base* __this_its = _M_this()._M_iterators;
 144       _M_swap_aux(__other, __other._M_iterators,
 145                   _M_this(), _M_this()._M_iterators);
 146       _Safe_iterator_base* __this_const_its = _M_this()._M_const_iterators;
 147       _M_swap_aux(__other, __other._M_const_iterators,
 148                   _M_this(), _M_this()._M_const_iterators);
 149       _M_swap_aux(_M_this(), __this_its,
 150                   __other, __other._M_iterators);
 151       _M_swap_aux(_M_this(), __this_const_its,
 152                   __other, __other._M_const_iterators);
 153     }
 154
 155   /* Special forward_list _M_swap version that does not swap the
 156    * before-begin ownership.*/
 157    template<typename _SafeSequence>
 158     void
 159     _Safe_forward_list<_SafeSequence>::
 160     _M_swap(_Safe_sequence_base& __other) noexcept
 161     {
 162       // We need to lock both sequences to swap
 163       using namespace __gnu_cxx;
 164       __mutex *__this_mutex = &_M_this()._M_get_mutex();
 165       __mutex *__other_mutex =
 166         &static_cast<_SafeSequence&>(__other)._M_get_mutex();
 167       if (__this_mutex == __other_mutex)
 168         {
 169           __scoped_lock __lock(*__this_mutex);
 170           _M_swap_single(__other);
 171         }
 172       else
 173         {
 174           __scoped_lock __l1(__this_mutex < __other_mutex
 175                              ? *__this_mutex : *__other_mutex);
 176           __scoped_lock __l2(__this_mutex < __other_mutex
 177                              ? *__other_mutex : *__this_mutex);
 178           _M_swap_single(__other);
 179         }
 180     }
 181 }
 182
 183 namespace std _GLIBCXX_VISIBILITY(default)
 184 {
 185 namespace __debug
 186 {
 187   /// Class std::forward_list with safety/checking/debug instrumentation.
 188   template<typename _Tp, typename _Alloc = std::allocator<_Tp> >
 189     class forward_list
 190     : public __gnu_debug::_Safe_container<
 191         forward_list<_Tp, _Alloc>, _Alloc, __gnu_debug::_Safe_forward_list>,
 192       public _GLIBCXX_STD_C::forward_list<_Tp, _Alloc>
 193     {
 194       typedef _GLIBCXX_STD_C::forward_list<_Tp, _Alloc>         _Base;
 195       typedef __gnu_debug::_Safe_container<
 196         forward_list, _Alloc, __gnu_debug::_Safe_forward_list>  _Safe;
 197
 198       typedef typename _Base::iterator          _Base_iterator;
 199       typedef typename _Base::const_iterator    _Base_const_iterator;
 200
 201       template<typename _ItT, typename _SeqT, typename _CatT>
 202         friend class ::__gnu_debug::_Safe_iterator;
 203
 204     public:
 205       typedef typename _Base::reference         reference;
 206       typedef typename _Base::const_reference   const_reference;
 207
 208       typedef __gnu_debug::_Safe_iterator<
 209         _Base_iterator, forward_list>           iterator;
 210       typedef __gnu_debug::_Safe_iterator<
 211         _Base_const_iterator, forward_list>     const_iterator;
 212
 213       typedef typename _Base::size_type         size_type;
 214       typedef typename _Base::difference_type   difference_type;
 215
 216       typedef _Tp                               value_type;
 217       typedef typename _Base::allocator_type    allocator_type;
 218       typedef typename _Base::pointer           pointer;
 219       typedef typename _Base::const_pointer     const_pointer;
 220
 221       // 23.2.3.1 construct/copy/destroy:
 222
 223       forward_list() = default;
 224
 225       explicit
 226       forward_list(const allocator_type& __al) noexcept
 227       : _Base(__al) { }
 228
 229       forward_list(const forward_list& __list, const allocator_type& __al)
 230       : _Base(__list, __al)
 231       { }
 232
 233       forward_list(forward_list&& __list, const allocator_type& __al)
 234         : _Safe(std::move(__list._M_safe()), __al),
 235           _Base(std::move(__list._M_base()), __al)
 236       { }
 237
 238       explicit
 239       forward_list(size_type __n, const allocator_type& __al = allocator_type())
 240       : _Base(__n, __al)
 241       { }
 242
 243       forward_list(size_type __n, const _Tp& __value,
 244                    const allocator_type& __al = allocator_type())
 245       : _Base(__n, __value, __al)
 246       { }
 247
 248       template<typename _InputIterator,
 249                typename = std::_RequireInputIter<_InputIterator>>
 250         forward_list(_InputIterator __first, _InputIterator __last,
 251                      const allocator_type& __al = allocator_type())
 252         : _Base(__gnu_debug::__base(
 253                   __glibcxx_check_valid_constructor_range(__first, __last)),
 254                 __gnu_debug::__base(__last), __al)
 255         { }
 256
 257       forward_list(const forward_list&) = default;
 258
 259       forward_list(forward_list&&) = default;
 260
 261       forward_list(std::initializer_list<_Tp> __il,
 262                    const allocator_type& __al = allocator_type())
 263       : _Base(__il, __al)
 264       { }
 265
 266       ~forward_list() = default;
 267
 268       forward_list&
 269       operator=(const forward_list&) = default;
 270
 271       forward_list&
 272       operator=(forward_list&&) = default;
 273
 274       forward_list&
 275       operator=(std::initializer_list<_Tp> __il)
 276       {
 277         _M_base() = __il;
 278         this->_M_invalidate_all();
 279         return *this;
 280       }
 281
 282       template<typename _InputIterator,
 283                typename = std::_RequireInputIter<_InputIterator>>
 284         void
 285         assign(_InputIterator __first, _InputIterator __last)
 286         {
 287           typename __gnu_debug::_Distance_traits<_InputIterator>::__type __dist;
 288           __glibcxx_check_valid_range2(__first, __last, __dist);
 289
 290           if (__dist.second >= __gnu_debug::__dp_sign)
 291             _Base::assign(__gnu_debug::__unsafe(__first),
 292                           __gnu_debug::__unsafe(__last));
 293           else
 294             _Base::assign(__first, __last);
 295
 296           this->_M_invalidate_all();
 297         }
 298
 299       void
 300       assign(size_type __n, const _Tp& __val)
 301       {
 302         _Base::assign(__n, __val);
 303         this->_M_invalidate_all();
 304       }
 305
 306       void
 307       assign(std::initializer_list<_Tp> __il)
 308       {
 309         _Base::assign(__il);
 310         this->_M_invalidate_all();
 311       }
 312
 313       using _Base::get_allocator;
 314
 315       // iterators:
 316
 317       iterator
 318       before_begin() noexcept
 319       { return { _Base::before_begin(), this }; }
 320
 321       const_iterator
 322       before_begin() const noexcept
 323       { return { _Base::before_begin(), this }; }
 324
 325       iterator
 326       begin() noexcept
 327       { return { _Base::begin(), this }; }
 328
 329       const_iterator
 330       begin() const noexcept
 331       { return { _Base::begin(), this }; }
 332
 333       iterator
 334       end() noexcept
 335       { return { _Base::end(), this }; }
 336
 337       const_iterator
 338       end() const noexcept
 339       { return { _Base::end(), this }; }
 340
 341       const_iterator
 342       cbegin() const noexcept
 343       { return { _Base::cbegin(), this }; }
 344
 345       const_iterator
 346       cbefore_begin() const noexcept
 347       { return { _Base::cbefore_begin(), this }; }
 348
 349       const_iterator
 350       cend() const noexcept
 351       { return { _Base::cend(), this }; }
 352
 353       using _Base::empty;
 354       using _Base::max_size;
 355
 356       // element access:
 357
 358       reference
 359       front()
 360       {
 361         __glibcxx_check_nonempty();
 362         return _Base::front();
 363       }
 364
 365       const_reference
 366       front() const
 367       {
 368         __glibcxx_check_nonempty();
 369         return _Base::front();
 370       }
 371
 372       // modifiers:
 373
 374       using _Base::emplace_front;
 375       using _Base::push_front;
 376
 377       void
 378       pop_front()
 379       {
 380         __glibcxx_check_nonempty();
 381         this->_M_invalidate_if([this](_Base_const_iterator __it)
 382           { return __it == this->_M_base().cbegin(); });
 383         _Base::pop_front();
 384       }
 385
 386       template<typename... _Args>
 387         iterator
 388         emplace_after(const_iterator __pos, _Args&&... __args)
 389         {
 390           __glibcxx_check_insert_after(__pos);
 391           return { _Base::emplace_after(__pos.base(),
 392                                         std::forward<_Args>(__args)...),
 393                    this };
 394         }
 395
 396       iterator
 397       insert_after(const_iterator __pos, const _Tp& __val)
 398       {
 399         __glibcxx_check_insert_after(__pos);
 400         return { _Base::insert_after(__pos.base(), __val), this };
 401       }
 402
 403       iterator
 404       insert_after(const_iterator __pos, _Tp&& __val)
 405       {
 406         __glibcxx_check_insert_after(__pos);
 407         return { _Base::insert_after(__pos.base(), std::move(__val)), this };
 408       }
 409
 410       iterator
 411       insert_after(const_iterator __pos, size_type __n, const _Tp& __val)
 412       {
 413         __glibcxx_check_insert_after(__pos);
 414         return { _Base::insert_after(__pos.base(), __n, __val), this };
 415       }
 416
 417       template<typename _InputIterator,
 418                typename = std::_RequireInputIter<_InputIterator>>
 419         iterator
 420         insert_after(const_iterator __pos,
 421                      _InputIterator __first, _InputIterator __last)
 422         {
 423           typename __gnu_debug::_Distance_traits<_InputIterator>::__type __dist;
 424           __glibcxx_check_insert_range_after(__pos, __first, __last, __dist);
 425
 426           if (__dist.second >= __gnu_debug::__dp_sign)
 427             return
 428               {
 429                 _Base::insert_after(__pos.base(),
 430                                     __gnu_debug::__unsafe(__first),
 431                                     __gnu_debug::__unsafe(__last)),
 432                 this
 433               };
 434           else
 435             return { _Base::insert_after(__pos.base(), __first, __last), this };
 436         }
 437
 438       iterator
 439       insert_after(const_iterator __pos, std::initializer_list<_Tp> __il)
 440       {
 441         __glibcxx_check_insert_after(__pos);
 442         return { _Base::insert_after(__pos.base(), __il), this };
 443       }
 444
 445     private:
 446       _Base_iterator
 447       _M_erase_after(_Base_const_iterator __pos)
 448       {
 449         _Base_const_iterator __next = std::next(__pos);
 450         this->_M_invalidate_if([__next](_Base_const_iterator __it)
 451           { return __it == __next; });
 452         return _Base::erase_after(__pos);
 453       }
 454     public:
 455       iterator
 456       erase_after(const_iterator __pos)
 457       {
 458         __glibcxx_check_erase_after(__pos);
 459         return { _M_erase_after(__pos.base()), this };
 460       }
 461
 462       iterator
 463       erase_after(const_iterator __pos, const_iterator __last)
 464       {
 465         __glibcxx_check_erase_range_after(__pos, __last);
 466         for (_Base_const_iterator __victim = std::next(__pos.base());
 467             __victim != __last.base(); ++__victim)
 468           {
 469             _GLIBCXX_DEBUG_VERIFY(__victim != _Base::cend(),
 470                                   _M_message(__gnu_debug::__msg_valid_range2)
 471                                   ._M_sequence(*this, "this")
 472                                   ._M_iterator(__pos, "pos")
 473                                   ._M_iterator(__last, "last"));
 474             this->_M_invalidate_if([__victim](_Base_const_iterator __it)
 475               { return __it == __victim; });
 476           }
 477
 478         return { _Base::erase_after(__pos.base(), __last.base()), this };
 479       }
 480
 481       void
 482       swap(forward_list& __list)
 483         noexcept( noexcept(declval<_Base&>().swap(__list)) )
 484       {
 485         _Safe::_M_swap(__list);
 486         _Base::swap(__list);
 487       }
 488
 489       void
 490       resize(size_type __sz)
 491       {
 492         this->_M_detach_singular();
 493
 494         // if __sz < size(), invalidate all iterators in [begin+__sz, end()
 495         _Base_iterator __victim = _Base::begin();
 496         _Base_iterator __end = _Base::end();
 497         for (size_type __i = __sz; __victim != __end && __i > 0; --__i)
 498           ++__victim;
 499
 500         for (; __victim != __end; ++__victim)
 501           {
 502             this->_M_invalidate_if([__victim](_Base_const_iterator __it)
 503               { return __it == __victim; });
 504           }
 505
 506         __try
 507           {
 508             _Base::resize(__sz);
 509           }
 510         __catch(...)
 511           {
 512             this->_M_revalidate_singular();
 513             __throw_exception_again;
 514           }
 515       }
 516
 517       void
 518       resize(size_type __sz, const value_type& __val)
 519       {
 520         this->_M_detach_singular();
 521
 522         // if __sz < size(), invalidate all iterators in [begin+__sz, end())
 523         _Base_iterator __victim = _Base::begin();
 524         _Base_iterator __end = _Base::end();
 525         for (size_type __i = __sz; __victim != __end && __i > 0; --__i)
 526           ++__victim;
 527
 528         for (; __victim != __end; ++__victim)
 529           {
 530             this->_M_invalidate_if([__victim](_Base_const_iterator __it)
 531               { return __it == __victim; });
 532           }
 533
 534         __try
 535           {
 536             _Base::resize(__sz, __val);
 537           }
 538         __catch(...)
 539           {
 540             this->_M_revalidate_singular();
 541             __throw_exception_again;
 542           }
 543       }
 544
 545       void
 546       clear() noexcept
 547       {
 548         _Base::clear();
 549         this->_M_invalidate_all();
 550       }
 551
 552       // 23.2.3.5 forward_list operations:
 553       void
 554       splice_after(const_iterator __pos, forward_list&& __list)
 555       {
 556         __glibcxx_check_insert_after(__pos);
 557         _GLIBCXX_DEBUG_VERIFY(std::__addressof(__list) != this,
 558                               _M_message(__gnu_debug::__msg_self_splice)
 559                               ._M_sequence(*this, "this"));
 560         _GLIBCXX_DEBUG_VERIFY(__list.get_allocator() == this->get_allocator(),
 561                               _M_message(__gnu_debug::__msg_splice_alloc)
 562                               ._M_sequence(*this)
 563                               ._M_sequence(__list, "__list"));
 564         this->_M_transfer_from_if(__list, [&__list](_Base_const_iterator __it)
 565           {
 566             return __it != __list._M_base().cbefore_begin()
 567                    && __it != __list._M_base().end();
 568           });
 569         _Base::splice_after(__pos.base(), std::move(__list._M_base()));
 570       }
 571
 572       void
 573       splice_after(const_iterator __pos, forward_list& __list)
 574       { splice_after(__pos, std::move(__list)); }
 575
 576       void
 577       splice_after(const_iterator __pos, forward_list&& __list,
 578                    const_iterator __i)
 579       {
 580         __glibcxx_check_insert_after(__pos);
 581         _GLIBCXX_DEBUG_VERIFY(__i._M_before_dereferenceable(),
 582                               _M_message(__gnu_debug::__msg_splice_bad)
 583                               ._M_iterator(__i, "__i"));
 584         _GLIBCXX_DEBUG_VERIFY(__i._M_attached_to(std::__addressof(__list)),
 585                               _M_message(__gnu_debug::__msg_splice_other)
 586                               ._M_iterator(__i, "__i")
 587                               ._M_sequence(__list, "__list"));
 588         _GLIBCXX_DEBUG_VERIFY(__list.get_allocator() == this->get_allocator(),
 589                               _M_message(__gnu_debug::__msg_splice_alloc)
 590                               ._M_sequence(*this)
 591                               ._M_sequence(__list, "__list"));
 592
 593         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 594         // 250. splicing invalidates iterators
 595         _Base_const_iterator __next = std::next(__i.base());
 596         this->_M_transfer_from_if(__list, [__next](_Base_const_iterator __it)
 597           { return __it == __next; });
 598         _Base::splice_after(__pos.base(), std::move(__list._M_base()),
 599                             __i.base());
 600       }
 601
 602       void
 603       splice_after(const_iterator __pos, forward_list& __list,
 604                    const_iterator __i)
 605       { splice_after(__pos, std::move(__list), __i); }
 606
 607       void
 608       splice_after(const_iterator __pos, forward_list&& __list,
 609                    const_iterator __before, const_iterator __last)
 610       {
 611         typename __gnu_debug::_Distance_traits<const_iterator>::__type __dist;
 612         auto __listptr = std::__addressof(__list);
 613         __glibcxx_check_insert_after(__pos);
 614         __glibcxx_check_valid_fl_range(__before, __last, __dist);
 615         _GLIBCXX_DEBUG_VERIFY(__before._M_attached_to(__listptr),
 616                               _M_message(__gnu_debug::__msg_splice_other)
 617                               ._M_sequence(__list, "list")
 618                               ._M_iterator(__before, "before"));
 619         _GLIBCXX_DEBUG_VERIFY(__before._M_dereferenceable()
 620                               || __before._M_is_before_begin(),
 621                               _M_message(__gnu_debug::__msg_valid_range2)
 622                               ._M_sequence(__list, "list")
 623                               ._M_iterator(__before, "before")
 624                               ._M_iterator(__last, "last"));
 625         _GLIBCXX_DEBUG_VERIFY(__before != __last,
 626                               _M_message(__gnu_debug::__msg_valid_range2)
 627                               ._M_sequence(__list, "list")
 628                               ._M_iterator(__before, "before")
 629                               ._M_iterator(__last, "last"));
 630         _GLIBCXX_DEBUG_VERIFY(__list.get_allocator() == this->get_allocator(),
 631                               _M_message(__gnu_debug::__msg_splice_alloc)
 632                               ._M_sequence(*this)
 633                               ._M_sequence(__list, "__list"));
 634
 635         for (_Base_const_iterator __tmp = std::next(__before.base());
 636              __tmp != __last.base(); ++__tmp)
 637           {
 638             _GLIBCXX_DEBUG_VERIFY(__tmp != __list._M_base().end(),
 639                                   _M_message(__gnu_debug::__msg_valid_range2)
 640                                   ._M_sequence(__list, "list")
 641                                   ._M_iterator(__before, "before")
 642                                   ._M_iterator(__last, "last"));
 643             _GLIBCXX_DEBUG_VERIFY(__listptr != this || __tmp != __pos.base(),
 644                                   _M_message(__gnu_debug::__msg_splice_overlap)
 645                                   ._M_iterator(__tmp, "position")
 646                                   ._M_iterator(__before, "before")
 647                                   ._M_iterator(__last, "last"));
 648             // _GLIBCXX_RESOLVE_LIB_DEFECTS
 649             // 250. splicing invalidates iterators
 650             this->_M_transfer_from_if(__list, [__tmp](_Base_const_iterator __it)
 651               { return __it == __tmp; });
 652           }
 653
 654         _Base::splice_after(__pos.base(), std::move(__list._M_base()),
 655                             __before.base(), __last.base());
 656       }
 657
 658       void
 659       splice_after(const_iterator __pos, forward_list& __list,
 660                    const_iterator __before, const_iterator __last)
 661       { splice_after(__pos, std::move(__list), __before, __last); }
 662
 663     private:
 664 #if __cplusplus > 201703L
 665       using __remove_return_type = size_type;
 666 # define _GLIBCXX_FWDLIST_REMOVE_RETURN_TYPE_TAG \
 667       __attribute__((__abi_tag__("__cxx20")))
 668 # define _GLIBCXX20_ONLY(__expr) __expr
 669 #else
 670       using __remove_return_type = void;
 671 # define _GLIBCXX_FWDLIST_REMOVE_RETURN_TYPE_TAG
 672 # define _GLIBCXX20_ONLY(__expr)
 673 #endif
 674
 675     public:
 676       _GLIBCXX_FWDLIST_REMOVE_RETURN_TYPE_TAG
 677       __remove_return_type
 678       remove(const _Tp& __val)
 679       {
 680         if (!this->_M_iterators && !this->_M_const_iterators)
 681           return _Base::remove(__val);
 682
 683         size_type __removed __attribute__((__unused__)) = 0;
 684         _Base_iterator __x = _Base::before_begin();
 685         _Base_iterator __old = __x++;
 686         _Base_iterator __extra = _Base::end();
 687         while (__x != _Base::end())
 688           {
 689             if (*__x == __val)
 690               {
 691                 if (std::__addressof(*__x) != std::__addressof(__val))
 692                   {
 693                     __x = _M_erase_after(__old);
 694                     _GLIBCXX20_ONLY( __removed++ );
 695                     continue;
 696                   }
 697                 else
 698                   __extra = __old;
 699               }
 700             __old = __x++;
 701           }
 702
 703         if (__extra != _Base::end())
 704           {
 705             this->_M_erase_after(__extra);
 706             _GLIBCXX20_ONLY( __removed++ );
 707           }
 708
 709         return _GLIBCXX20_ONLY( __removed );
 710       }
 711
 712       template<typename _Pred>
 713         __remove_return_type
 714         remove_if(_Pred __pred)
 715         {
 716           if (!this->_M_iterators && !this->_M_const_iterators)
 717             return _Base::remove_if(__pred);
 718
 719           size_type __removed __attribute__((__unused__)) = 0;
 720           _Base_iterator __x = _Base::before_begin();
 721           _Base_iterator __old = __x++;
 722           while (__x != _Base::end())
 723             if (__pred(*__x))
 724               {
 725                 __x = _M_erase_after(__old);
 726                 _GLIBCXX20_ONLY( __removed++ );
 727               }
 728             else
 729               __old = __x++;
 730
 731           return _GLIBCXX20_ONLY( __removed );
 732         }
 733
 734       _GLIBCXX_FWDLIST_REMOVE_RETURN_TYPE_TAG
 735       __remove_return_type
 736       unique()
 737       { return unique(std::equal_to<_Tp>()); }
 738
 739       template<typename _BinPred>
 740         __remove_return_type
 741         unique(_BinPred __binary_pred)
 742         {
 743           if (!this->_M_iterators && !this->_M_const_iterators)
 744             return _Base::unique(__binary_pred);
 745
 746           _Base_iterator __first = _Base::begin();
 747           _Base_iterator __last = _Base::end();
 748           if (__first == __last)
 749             return _GLIBCXX20_ONLY(0);
 750
 751           size_type __removed __attribute__((__unused__)) = 0;
 752           _Base_iterator __next = std::next(__first);
 753           while (__next != __last)
 754             {
 755               if (__binary_pred(*__first, *__next))
 756                 {
 757                   __next = _M_erase_after(__first);
 758                   _GLIBCXX20_ONLY( __removed++ );
 759                 }
 760               else
 761                 __first = __next++;
 762             }
 763
 764           return _GLIBCXX20_ONLY( __removed );
 765         }
 766
 767 #undef _GLIBCXX_FWDLIST_REMOVE_RETURN_TYPE_TAG
 768 #undef _GLIBCXX20_ONLY
 769
 770       void
 771       merge(forward_list&& __list)
 772       {
 773         if (this != std::__addressof(__list))
 774         {
 775           __glibcxx_check_sorted(_Base::begin(), _Base::end());
 776           __glibcxx_check_sorted(__list._M_base().begin(),
 777                                  __list._M_base().end());
 778           this->_M_transfer_from_if(__list, [&__list](_Base_const_iterator __it)
 779             {
 780               return __it != __list._M_base().cbefore_begin()
 781                      && __it != __list._M_base().cend();
 782             });
 783           _Base::merge(std::move(__list._M_base()));
 784         }
 785       }
 786
 787       void
 788       merge(forward_list& __list)
 789       { merge(std::move(__list)); }
 790
 791       template<typename _Comp>
 792         void
 793         merge(forward_list&& __list, _Comp __comp)
 794         {
 795           if (this != std::__addressof(__list))
 796           {
 797             __glibcxx_check_sorted_pred(_Base::begin(), _Base::end(), __comp);
 798             __glibcxx_check_sorted_pred(__list._M_base().begin(),
 799                                         __list._M_base().end(), __comp);
 800             this->_M_transfer_from_if(__list,
 801                                       [&__list](_Base_const_iterator __it)
 802               {
 803                 return __it != __list._M_base().cbefore_begin()
 804                        && __it != __list._M_base().cend();
 805               });
 806             _Base::merge(std::move(__list._M_base()), __comp);
 807           }
 808         }
 809
 810       template<typename _Comp>
 811         void
 812         merge(forward_list& __list, _Comp __comp)
 813         { merge(std::move(__list), __comp); }
 814
 815       using _Base::sort;
 816       using _Base::reverse;
 817
 818       _Base&
 819       _M_base() noexcept { return *this; }
 820
 821       const _Base&
 822       _M_base() const noexcept { return *this; }
 823     };
 824
 825 #if __cpp_deduction_guides >= 201606
 826   template<typename _InputIterator, typename _ValT
 827              = typename iterator_traits<_InputIterator>::value_type,
 828            typename _Allocator = allocator<_ValT>,
 829            typename = _RequireInputIter<_InputIterator>,
 830            typename = _RequireAllocator<_Allocator>>
 831     forward_list(_InputIterator, _InputIterator, _Allocator = _Allocator())
 832       -> forward_list<_ValT, _Allocator>;
 833 #endif
 834
 835   template<typename _Tp, typename _Alloc>
 836     bool
 837     operator==(const forward_list<_Tp, _Alloc>& __lx,
 838                const forward_list<_Tp, _Alloc>& __ly)
 839     { return __lx._M_base() == __ly._M_base(); }
 840
 841   template<typename _Tp, typename _Alloc>
 842     inline bool
 843     operator<(const forward_list<_Tp, _Alloc>& __lx,
 844               const forward_list<_Tp, _Alloc>& __ly)
 845     { return __lx._M_base() < __ly._M_base(); }
 846
 847   template<typename _Tp, typename _Alloc>
 848     inline bool
 849     operator!=(const forward_list<_Tp, _Alloc>& __lx,
 850                const forward_list<_Tp, _Alloc>& __ly)
 851     { return !(__lx == __ly); }
 852
 853   /// Based on operator<
 854   template<typename _Tp, typename _Alloc>
 855     inline bool
 856     operator>(const forward_list<_Tp, _Alloc>& __lx,
 857               const forward_list<_Tp, _Alloc>& __ly)
 858     { return (__ly < __lx); }
 859
 860   /// Based on operator<
 861   template<typename _Tp, typename _Alloc>
 862     inline bool
 863     operator>=(const forward_list<_Tp, _Alloc>& __lx,
 864                const forward_list<_Tp, _Alloc>& __ly)
 865     { return !(__lx < __ly); }
 866
 867   /// Based on operator<
 868   template<typename _Tp, typename _Alloc>
 869     inline bool
 870     operator<=(const forward_list<_Tp, _Alloc>& __lx,
 871                const forward_list<_Tp, _Alloc>& __ly)
 872     { return !(__ly < __lx); }
 873
 874   /// See std::forward_list::swap().
 875   template<typename _Tp, typename _Alloc>
 876     inline void
 877     swap(forward_list<_Tp, _Alloc>& __lx, forward_list<_Tp, _Alloc>& __ly)
 878     noexcept(noexcept(__lx.swap(__ly)))
 879     { __lx.swap(__ly); }
 880
 881 } // namespace __debug
 882 } // namespace std
 883
 884 namespace __gnu_debug
 885 {
 886   template<typename _Tp, typename _Alloc>
 887     struct _BeforeBeginHelper<std::__debug::forward_list<_Tp, _Alloc> >
 888     {
 889       typedef std::__debug::forward_list<_Tp, _Alloc> _Sequence;
 890
 891       template<typename _Iterator>
 892         static bool
 893         _S_Is(const _Safe_iterator<_Iterator, _Sequence>& __it)
 894         {
 895           return
 896             __it.base() == __it._M_get_sequence()->_M_base().before_begin();
 897         }
 898
 899       template<typename _Iterator>
 900         static bool
 901         _S_Is_Beginnest(const _Safe_iterator<_Iterator, _Sequence>& __it)
 902         { return _S_Is(__it); }
 903     };
 904
 905   template<typename _Tp, typename _Alloc>
 906     struct _Sequence_traits<std::__debug::forward_list<_Tp, _Alloc> >
 907     {
 908       typedef typename std::__debug::forward_list<_Tp, _Alloc>::iterator _It;
 909
 910       static typename _Distance_traits<_It>::__type
 911       _S_size(const std::__debug::forward_list<_Tp, _Alloc>& __seq)
 912       {
 913         return __seq.empty()
 914           ? std::make_pair(0, __dp_exact) : std::make_pair(1, __dp_sign);
 915       }
 916     };
 917
 918 #ifndef _GLIBCXX_DEBUG_PEDANTIC
 919   template<class _Tp, class _Alloc>
 920     struct _Insert_range_from_self_is_safe<
 921       std::__debug::forward_list<_Tp, _Alloc> >
 922     { enum { __value = 1 }; };
 923 #endif
 924 }
 925
 926 #endif