libstdc++
debug/forward_list
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1 // <forward_list> -*- C++ -*-
2 
3 // Copyright (C) 2010-2021 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  // Reference wrapper for base class. See PR libstdc++/90102.
205  struct _Base_ref
206  {
207  _Base_ref(const _Base& __r) : _M_ref(__r) { }
208 
209  const _Base& _M_ref;
210  };
211 
212  public:
213  typedef typename _Base::reference reference;
214  typedef typename _Base::const_reference const_reference;
215 
216  typedef __gnu_debug::_Safe_iterator<
217  _Base_iterator, forward_list> iterator;
218  typedef __gnu_debug::_Safe_iterator<
219  _Base_const_iterator, forward_list> const_iterator;
220 
221  typedef typename _Base::size_type size_type;
222  typedef typename _Base::difference_type difference_type;
223 
224  typedef _Tp value_type;
225  typedef typename _Base::allocator_type allocator_type;
226  typedef typename _Base::pointer pointer;
227  typedef typename _Base::const_pointer const_pointer;
228 
229  // 23.2.3.1 construct/copy/destroy:
230 
231  forward_list() = default;
232 
233  explicit
234  forward_list(const allocator_type& __al) noexcept
235  : _Base(__al) { }
236 
237  forward_list(const forward_list& __list, const allocator_type& __al)
238  : _Base(__list, __al)
239  { }
240 
241  forward_list(forward_list&& __list, const allocator_type& __al)
242  noexcept(
243  std::is_nothrow_constructible<_Base,
244  _Base, const allocator_type&>::value )
245  : _Safe(std::move(__list._M_safe()), __al),
246  _Base(std::move(__list._M_base()), __al)
247  { }
248 
249  explicit
250  forward_list(size_type __n, const allocator_type& __al = allocator_type())
251  : _Base(__n, __al)
252  { }
253 
254  forward_list(size_type __n, const __type_identity_t<_Tp>& __value,
255  const allocator_type& __al = allocator_type())
256  : _Base(__n, __value, __al)
257  { }
258 
259  template<typename _InputIterator,
260  typename = std::_RequireInputIter<_InputIterator>>
261  forward_list(_InputIterator __first, _InputIterator __last,
262  const allocator_type& __al = allocator_type())
263  : _Base(__gnu_debug::__base(
264  __glibcxx_check_valid_constructor_range(__first, __last)),
265  __gnu_debug::__base(__last), __al)
266  { }
267 
268  forward_list(const forward_list&) = default;
269 
270  forward_list(forward_list&&) = default;
271 
272  forward_list(std::initializer_list<_Tp> __il,
273  const allocator_type& __al = allocator_type())
274  : _Base(__il, __al)
275  { }
276 
277  ~forward_list() = default;
278 
279  forward_list(_Base_ref __x) : _Base(__x._M_ref) { }
280 
281  forward_list&
282  operator=(const forward_list&) = default;
283 
284  forward_list&
285  operator=(forward_list&&) = default;
286 
287  forward_list&
288  operator=(std::initializer_list<_Tp> __il)
289  {
290  _M_base() = __il;
291  this->_M_invalidate_all();
292  return *this;
293  }
294 
295  template<typename _InputIterator,
296  typename = std::_RequireInputIter<_InputIterator>>
297  void
298  assign(_InputIterator __first, _InputIterator __last)
299  {
300  typename __gnu_debug::_Distance_traits<_InputIterator>::__type __dist;
301  __glibcxx_check_valid_range2(__first, __last, __dist);
302 
303  if (__dist.second >= __gnu_debug::__dp_sign)
304  _Base::assign(__gnu_debug::__unsafe(__first),
305  __gnu_debug::__unsafe(__last));
306  else
307  _Base::assign(__first, __last);
308 
309  this->_M_invalidate_all();
310  }
311 
312  void
313  assign(size_type __n, const _Tp& __val)
314  {
315  _Base::assign(__n, __val);
316  this->_M_invalidate_all();
317  }
318 
319  void
320  assign(std::initializer_list<_Tp> __il)
321  {
322  _Base::assign(__il);
323  this->_M_invalidate_all();
324  }
325 
326  using _Base::get_allocator;
327 
328  // iterators:
329 
330  iterator
331  before_begin() noexcept
332  { return { _Base::before_begin(), this }; }
333 
334  const_iterator
335  before_begin() const noexcept
336  { return { _Base::before_begin(), this }; }
337 
338  iterator
339  begin() noexcept
340  { return { _Base::begin(), this }; }
341 
342  const_iterator
343  begin() const noexcept
344  { return { _Base::begin(), this }; }
345 
346  iterator
347  end() noexcept
348  { return { _Base::end(), this }; }
349 
350  const_iterator
351  end() const noexcept
352  { return { _Base::end(), this }; }
353 
354  const_iterator
355  cbegin() const noexcept
356  { return { _Base::cbegin(), this }; }
357 
358  const_iterator
359  cbefore_begin() const noexcept
360  { return { _Base::cbefore_begin(), this }; }
361 
362  const_iterator
363  cend() const noexcept
364  { return { _Base::cend(), this }; }
365 
366  using _Base::empty;
367  using _Base::max_size;
368 
369  // element access:
370 
371  reference
372  front()
373  {
374  __glibcxx_check_nonempty();
375  return _Base::front();
376  }
377 
378  const_reference
379  front() const
380  {
381  __glibcxx_check_nonempty();
382  return _Base::front();
383  }
384 
385  // modifiers:
386 
387  using _Base::emplace_front;
388  using _Base::push_front;
389 
390  void
391  pop_front()
392  {
393  __glibcxx_check_nonempty();
394  this->_M_invalidate_if([this](_Base_const_iterator __it)
395  { return __it == this->_M_base().cbegin(); });
396  _Base::pop_front();
397  }
398 
399  template<typename... _Args>
400  iterator
401  emplace_after(const_iterator __pos, _Args&&... __args)
402  {
403  __glibcxx_check_insert_after(__pos);
404  return { _Base::emplace_after(__pos.base(),
405  std::forward<_Args>(__args)...),
406  this };
407  }
408 
409  iterator
410  insert_after(const_iterator __pos, const _Tp& __val)
411  {
412  __glibcxx_check_insert_after(__pos);
413  return { _Base::insert_after(__pos.base(), __val), this };
414  }
415 
416  iterator
417  insert_after(const_iterator __pos, _Tp&& __val)
418  {
419  __glibcxx_check_insert_after(__pos);
420  return { _Base::insert_after(__pos.base(), std::move(__val)), this };
421  }
422 
423  iterator
424  insert_after(const_iterator __pos, size_type __n, const _Tp& __val)
425  {
426  __glibcxx_check_insert_after(__pos);
427  return { _Base::insert_after(__pos.base(), __n, __val), this };
428  }
429 
430  template<typename _InputIterator,
431  typename = std::_RequireInputIter<_InputIterator>>
432  iterator
433  insert_after(const_iterator __pos,
434  _InputIterator __first, _InputIterator __last)
435  {
436  typename __gnu_debug::_Distance_traits<_InputIterator>::__type __dist;
437  __glibcxx_check_insert_range_after(__pos, __first, __last, __dist);
438 
439  if (__dist.second >= __gnu_debug::__dp_sign)
440  return
441  {
442  _Base::insert_after(__pos.base(),
443  __gnu_debug::__unsafe(__first),
444  __gnu_debug::__unsafe(__last)),
445  this
446  };
447  else
448  return { _Base::insert_after(__pos.base(), __first, __last), this };
449  }
450 
451  iterator
452  insert_after(const_iterator __pos, std::initializer_list<_Tp> __il)
453  {
454  __glibcxx_check_insert_after(__pos);
455  return { _Base::insert_after(__pos.base(), __il), this };
456  }
457 
458  iterator
459  erase_after(const_iterator __pos)
460  {
461  __glibcxx_check_erase_after(__pos);
462 
463  _Base_const_iterator __next = std::next(__pos.base());
464  this->_M_invalidate_if([__next](_Base_const_iterator __it)
465  { return __it == __next; });
466  return { _Base::erase_after(__pos.base()), this };
467  }
468 
469  iterator
470  erase_after(const_iterator __pos, const_iterator __last)
471  {
472  __glibcxx_check_erase_range_after(__pos, __last);
473  for (_Base_const_iterator __victim = std::next(__pos.base());
474  __victim != __last.base(); ++__victim)
475  {
476  _GLIBCXX_DEBUG_VERIFY(__victim != _Base::cend(),
477  _M_message(__gnu_debug::__msg_valid_range2)
478  ._M_sequence(*this, "this")
479  ._M_iterator(__pos, "pos")
480  ._M_iterator(__last, "last"));
481  this->_M_invalidate_if([__victim](_Base_const_iterator __it)
482  { return __it == __victim; });
483  }
484 
485  return { _Base::erase_after(__pos.base(), __last.base()), this };
486  }
487 
488  void
489  swap(forward_list& __list)
490  noexcept( noexcept(declval<_Base&>().swap(__list)) )
491  {
492  _Safe::_M_swap(__list);
493  _Base::swap(__list);
494  }
495 
496  void
497  resize(size_type __sz)
498  {
499  this->_M_detach_singular();
500 
501  // if __sz < size(), invalidate all iterators in [begin+__sz, end()
502  _Base_iterator __victim = _Base::begin();
503  _Base_iterator __end = _Base::end();
504  for (size_type __i = __sz; __victim != __end && __i > 0; --__i)
505  ++__victim;
506 
507  for (; __victim != __end; ++__victim)
508  {
509  this->_M_invalidate_if([__victim](_Base_const_iterator __it)
510  { return __it == __victim; });
511  }
512 
513  __try
514  {
515  _Base::resize(__sz);
516  }
517  __catch(...)
518  {
519  this->_M_revalidate_singular();
520  __throw_exception_again;
521  }
522  }
523 
524  void
525  resize(size_type __sz, const value_type& __val)
526  {
527  this->_M_detach_singular();
528 
529  // if __sz < size(), invalidate all iterators in [begin+__sz, end())
530  _Base_iterator __victim = _Base::begin();
531  _Base_iterator __end = _Base::end();
532  for (size_type __i = __sz; __victim != __end && __i > 0; --__i)
533  ++__victim;
534 
535  for (; __victim != __end; ++__victim)
536  {
537  this->_M_invalidate_if([__victim](_Base_const_iterator __it)
538  { return __it == __victim; });
539  }
540 
541  __try
542  {
543  _Base::resize(__sz, __val);
544  }
545  __catch(...)
546  {
547  this->_M_revalidate_singular();
548  __throw_exception_again;
549  }
550  }
551 
552  void
553  clear() noexcept
554  {
555  _Base::clear();
556  this->_M_invalidate_all();
557  }
558 
559  // 23.2.3.5 forward_list operations:
560  void
561  splice_after(const_iterator __pos, forward_list&& __list)
562  {
563  __glibcxx_check_insert_after(__pos);
564  _GLIBCXX_DEBUG_VERIFY(std::__addressof(__list) != this,
565  _M_message(__gnu_debug::__msg_self_splice)
566  ._M_sequence(*this, "this"));
567  _GLIBCXX_DEBUG_VERIFY(__list.get_allocator() == this->get_allocator(),
568  _M_message(__gnu_debug::__msg_splice_alloc)
569  ._M_sequence(*this)
570  ._M_sequence(__list, "__list"));
571  this->_M_transfer_from_if(__list, [&__list](_Base_const_iterator __it)
572  {
573  return __it != __list._M_base().cbefore_begin()
574  && __it != __list._M_base().end();
575  });
576  _Base::splice_after(__pos.base(), std::move(__list._M_base()));
577  }
578 
579  void
580  splice_after(const_iterator __pos, forward_list& __list)
581  { splice_after(__pos, std::move(__list)); }
582 
583  void
584  splice_after(const_iterator __pos, forward_list&& __list,
585  const_iterator __i)
586  {
587  __glibcxx_check_insert_after(__pos);
588  _GLIBCXX_DEBUG_VERIFY(__i._M_before_dereferenceable(),
589  _M_message(__gnu_debug::__msg_splice_bad)
590  ._M_iterator(__i, "__i"));
591  _GLIBCXX_DEBUG_VERIFY(__i._M_attached_to(std::__addressof(__list)),
592  _M_message(__gnu_debug::__msg_splice_other)
593  ._M_iterator(__i, "__i")
594  ._M_sequence(__list, "__list"));
595  _GLIBCXX_DEBUG_VERIFY(__list.get_allocator() == this->get_allocator(),
596  _M_message(__gnu_debug::__msg_splice_alloc)
597  ._M_sequence(*this)
598  ._M_sequence(__list, "__list"));
599 
600  // _GLIBCXX_RESOLVE_LIB_DEFECTS
601  // 250. splicing invalidates iterators
602  _Base_const_iterator __next = std::next(__i.base());
603  this->_M_transfer_from_if(__list, [__next](_Base_const_iterator __it)
604  { return __it == __next; });
605  _Base::splice_after(__pos.base(), std::move(__list._M_base()),
606  __i.base());
607  }
608 
609  void
610  splice_after(const_iterator __pos, forward_list& __list,
611  const_iterator __i)
612  { splice_after(__pos, std::move(__list), __i); }
613 
614  void
615  splice_after(const_iterator __pos, forward_list&& __list,
616  const_iterator __before, const_iterator __last)
617  {
618  typename __gnu_debug::_Distance_traits<const_iterator>::__type __dist;
619  auto __listptr = std::__addressof(__list);
620  __glibcxx_check_insert_after(__pos);
621  __glibcxx_check_valid_fl_range(__before, __last, __dist);
622  _GLIBCXX_DEBUG_VERIFY(__before._M_attached_to(__listptr),
623  _M_message(__gnu_debug::__msg_splice_other)
624  ._M_sequence(__list, "list")
625  ._M_iterator(__before, "before"));
626  _GLIBCXX_DEBUG_VERIFY(__before._M_dereferenceable()
627  || __before._M_is_before_begin(),
628  _M_message(__gnu_debug::__msg_valid_range2)
629  ._M_sequence(__list, "list")
630  ._M_iterator(__before, "before")
631  ._M_iterator(__last, "last"));
632  _GLIBCXX_DEBUG_VERIFY(__before != __last,
633  _M_message(__gnu_debug::__msg_valid_range2)
634  ._M_sequence(__list, "list")
635  ._M_iterator(__before, "before")
636  ._M_iterator(__last, "last"));
637  _GLIBCXX_DEBUG_VERIFY(__list.get_allocator() == this->get_allocator(),
638  _M_message(__gnu_debug::__msg_splice_alloc)
639  ._M_sequence(*this)
640  ._M_sequence(__list, "__list"));
641 
642  for (_Base_const_iterator __tmp = std::next(__before.base());
643  __tmp != __last.base(); ++__tmp)
644  {
645  _GLIBCXX_DEBUG_VERIFY(__tmp != __list._M_base().end(),
646  _M_message(__gnu_debug::__msg_valid_range2)
647  ._M_sequence(__list, "list")
648  ._M_iterator(__before, "before")
649  ._M_iterator(__last, "last"));
650  _GLIBCXX_DEBUG_VERIFY(__listptr != this || __tmp != __pos.base(),
651  _M_message(__gnu_debug::__msg_splice_overlap)
652  ._M_iterator(__tmp, "position")
653  ._M_iterator(__before, "before")
654  ._M_iterator(__last, "last"));
655  // _GLIBCXX_RESOLVE_LIB_DEFECTS
656  // 250. splicing invalidates iterators
657  this->_M_transfer_from_if(__list, [__tmp](_Base_const_iterator __it)
658  { return __it == __tmp; });
659  }
660 
661  _Base::splice_after(__pos.base(), std::move(__list._M_base()),
662  __before.base(), __last.base());
663  }
664 
665  void
666  splice_after(const_iterator __pos, forward_list& __list,
667  const_iterator __before, const_iterator __last)
668  { splice_after(__pos, std::move(__list), __before, __last); }
669 
670  private:
671 #if __cplusplus > 201703L
672  using __remove_return_type = size_type;
673 # define _GLIBCXX_FWDLIST_REMOVE_RETURN_TYPE_TAG \
674  __attribute__((__abi_tag__("__cxx20")))
675 # define _GLIBCXX20_ONLY(__expr) __expr
676 #else
677  using __remove_return_type = void;
678 # define _GLIBCXX_FWDLIST_REMOVE_RETURN_TYPE_TAG
679 # define _GLIBCXX20_ONLY(__expr)
680 #endif
681 
682  public:
683  _GLIBCXX_FWDLIST_REMOVE_RETURN_TYPE_TAG
684  __remove_return_type
685  remove(const _Tp& __val)
686  {
687  if (!this->_M_iterators && !this->_M_const_iterators)
688  return _Base::remove(__val);
689 
690  size_type __removed __attribute__((__unused__)) = 0;
691  _Base __to_destroy(get_allocator());
692  _Base_const_iterator __x = _Base::cbefore_begin();
693  _Base_const_iterator __old = __x++;
694  while (__x != _Base::cend())
695  {
696  if (*__x == __val)
697  {
698  _Base_const_iterator __next = std::next(__old);
699  this->_M_invalidate_if([__next](_Base_const_iterator __it)
700  { return __it == __next; });
701  __to_destroy.splice_after(__to_destroy.cbefore_begin(),
702  _M_base(), __old);
703  __x = __old;
704  _GLIBCXX20_ONLY( __removed++ );
705  }
706 
707  __old = __x++;
708  }
709 
710  return _GLIBCXX20_ONLY( __removed );
711  }
712 
713  template<typename _Pred>
714  __remove_return_type
715  remove_if(_Pred __pred)
716  {
717  if (!this->_M_iterators && !this->_M_const_iterators)
718  return _Base::remove_if(__pred);
719 
720  size_type __removed __attribute__((__unused__)) = 0;
721  _Base __to_destroy(get_allocator());
722  _Base_iterator __x = _Base::before_begin();
723  _Base_iterator __old = __x++;
724  while (__x != _Base::end())
725  {
726  if (__pred(*__x))
727  {
728  this->_M_invalidate_if([__x](_Base_const_iterator __it)
729  { return __it == __x; });
730  __to_destroy.splice_after(__to_destroy.cbefore_begin(),
731  _M_base(), __old);
732  __x = __old;
733  _GLIBCXX20_ONLY( __removed++ );
734  }
735 
736  __old = __x++;
737  }
738 
739  return _GLIBCXX20_ONLY( __removed );
740  }
741 
742  _GLIBCXX_FWDLIST_REMOVE_RETURN_TYPE_TAG
743  __remove_return_type
744  unique()
745  { return unique(std::equal_to<_Tp>()); }
746 
747  template<typename _BinPred>
748  __remove_return_type
749  unique(_BinPred __binary_pred)
750  {
751  if (!this->_M_iterators && !this->_M_const_iterators)
752  return _Base::unique(__binary_pred);
753 
754  _Base_const_iterator __first = _Base::cbegin();
755  _Base_const_iterator __last = _Base::cend();
756  if (__first == __last)
757  return _GLIBCXX20_ONLY(0);
758 
759  size_type __removed __attribute__((__unused__)) = 0;
760  _Base __to_destroy(get_allocator());
761  _Base_const_iterator __next = std::next(__first);
762  while (__next != __last)
763  {
764  if (__binary_pred(*__first, *__next))
765  {
766  this->_M_invalidate_if([__next](_Base_const_iterator __it)
767  { return __it == __next; });
768  __to_destroy.splice_after(__to_destroy.cbefore_begin(),
769  _M_base(), __first);
770  __next = __first;
771  _GLIBCXX20_ONLY( __removed++ );
772  }
773 
774  __first = __next++;
775  }
776 
777  return _GLIBCXX20_ONLY( __removed );
778  }
779 
780 #undef _GLIBCXX_FWDLIST_REMOVE_RETURN_TYPE_TAG
781 #undef _GLIBCXX20_ONLY
782 
783  void
784  merge(forward_list&& __list)
785  {
786  if (this != std::__addressof(__list))
787  {
788  __glibcxx_check_sorted(_Base::begin(), _Base::end());
789  __glibcxx_check_sorted(__list._M_base().begin(),
790  __list._M_base().end());
791  this->_M_transfer_from_if(__list, [&__list](_Base_const_iterator __it)
792  {
793  return __it != __list._M_base().cbefore_begin()
794  && __it != __list._M_base().cend();
795  });
796  _Base::merge(std::move(__list._M_base()));
797  }
798  }
799 
800  void
801  merge(forward_list& __list)
802  { merge(std::move(__list)); }
803 
804  template<typename _Comp>
805  void
806  merge(forward_list&& __list, _Comp __comp)
807  {
808  if (this != std::__addressof(__list))
809  {
810  __glibcxx_check_sorted_pred(_Base::begin(), _Base::end(), __comp);
811  __glibcxx_check_sorted_pred(__list._M_base().begin(),
812  __list._M_base().end(), __comp);
813  this->_M_transfer_from_if(__list,
814  [&__list](_Base_const_iterator __it)
815  {
816  return __it != __list._M_base().cbefore_begin()
817  && __it != __list._M_base().cend();
818  });
819  _Base::merge(std::move(__list._M_base()), __comp);
820  }
821  }
822 
823  template<typename _Comp>
824  void
825  merge(forward_list& __list, _Comp __comp)
826  { merge(std::move(__list), __comp); }
827 
828  using _Base::sort;
829  using _Base::reverse;
830 
831  _Base&
832  _M_base() noexcept { return *this; }
833 
834  const _Base&
835  _M_base() const noexcept { return *this; }
836  };
837 
838 #if __cpp_deduction_guides >= 201606
839  template<typename _InputIterator, typename _ValT
840  = typename iterator_traits<_InputIterator>::value_type,
841  typename _Allocator = allocator<_ValT>,
842  typename = _RequireInputIter<_InputIterator>,
843  typename = _RequireAllocator<_Allocator>>
844  forward_list(_InputIterator, _InputIterator, _Allocator = _Allocator())
845  -> forward_list<_ValT, _Allocator>;
846 
847  template<typename _Tp, typename _Allocator = allocator<_Tp>,
848  typename = _RequireAllocator<_Allocator>>
849  forward_list(size_t, _Tp, _Allocator = _Allocator())
850  -> forward_list<_Tp, _Allocator>;
851 #endif
852 
853  template<typename _Tp, typename _Alloc>
854  bool
855  operator==(const forward_list<_Tp, _Alloc>& __lx,
856  const forward_list<_Tp, _Alloc>& __ly)
857  { return __lx._M_base() == __ly._M_base(); }
858 
859 #if __cpp_lib_three_way_comparison
860  template<typename _Tp, typename _Alloc>
861  constexpr __detail::__synth3way_t<_Tp>
862  operator<=>(const forward_list<_Tp, _Alloc>& __x,
863  const forward_list<_Tp, _Alloc>& __y)
864  { return __x._M_base() <=> __y._M_base(); }
865 #else
866  template<typename _Tp, typename _Alloc>
867  inline bool
868  operator<(const forward_list<_Tp, _Alloc>& __lx,
869  const forward_list<_Tp, _Alloc>& __ly)
870  { return __lx._M_base() < __ly._M_base(); }
871 
872  template<typename _Tp, typename _Alloc>
873  inline bool
874  operator!=(const forward_list<_Tp, _Alloc>& __lx,
875  const forward_list<_Tp, _Alloc>& __ly)
876  { return !(__lx == __ly); }
877 
878  /// Based on operator<
879  template<typename _Tp, typename _Alloc>
880  inline bool
881  operator>(const forward_list<_Tp, _Alloc>& __lx,
882  const forward_list<_Tp, _Alloc>& __ly)
883  { return (__ly < __lx); }
884 
885  /// Based on operator<
886  template<typename _Tp, typename _Alloc>
887  inline bool
888  operator>=(const forward_list<_Tp, _Alloc>& __lx,
889  const forward_list<_Tp, _Alloc>& __ly)
890  { return !(__lx < __ly); }
891 
892  /// Based on operator<
893  template<typename _Tp, typename _Alloc>
894  inline bool
895  operator<=(const forward_list<_Tp, _Alloc>& __lx,
896  const forward_list<_Tp, _Alloc>& __ly)
897  { return !(__ly < __lx); }
898 #endif // three-way comparison
899 
900  /// See std::forward_list::swap().
901  template<typename _Tp, typename _Alloc>
902  inline void
903  swap(forward_list<_Tp, _Alloc>& __lx, forward_list<_Tp, _Alloc>& __ly)
904  noexcept(noexcept(__lx.swap(__ly)))
905  { __lx.swap(__ly); }
906 
907 } // namespace __debug
908 } // namespace std
909 
910 namespace __gnu_debug
911 {
912  template<typename _Tp, typename _Alloc>
913  struct _BeforeBeginHelper<std::__debug::forward_list<_Tp, _Alloc> >
914  {
915  typedef std::__debug::forward_list<_Tp, _Alloc> _Sequence;
916 
917  template<typename _Iterator>
918  static bool
919  _S_Is(const _Safe_iterator<_Iterator, _Sequence>& __it)
920  {
921  return
922  __it.base() == __it._M_get_sequence()->_M_base().before_begin();
923  }
924 
925  template<typename _Iterator>
926  static bool
927  _S_Is_Beginnest(const _Safe_iterator<_Iterator, _Sequence>& __it)
928  { return _S_Is(__it); }
929  };
930 
931  template<typename _Tp, typename _Alloc>
932  struct _Sequence_traits<std::__debug::forward_list<_Tp, _Alloc> >
933  {
934  typedef typename std::__debug::forward_list<_Tp, _Alloc>::iterator _It;
935 
936  static typename _Distance_traits<_It>::__type
937  _S_size(const std::__debug::forward_list<_Tp, _Alloc>& __seq)
938  {
939  return __seq.empty()
940  ? std::make_pair(0, __dp_exact) : std::make_pair(1, __dp_sign);
941  }
942  };
943 
944 #ifndef _GLIBCXX_DEBUG_PEDANTIC
945  template<class _Tp, class _Alloc>
946  struct _Insert_range_from_self_is_safe<
947  std::__debug::forward_list<_Tp, _Alloc> >
948  { enum { __value = 1 }; };
949 #endif
950 }
951 
952 #endif