libstdc++
forward_list.tcc
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1 // <forward_list.tcc> -*- C++ -*-
2 
3 // Copyright (C) 2008-2025 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
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22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /** @file bits/forward_list.tcc
26  * This is an internal header file, included by other library headers.
27  * Do not attempt to use it directly. @headername{forward_list}
28  */
29 
30 #ifndef _FORWARD_LIST_TCC
31 #define _FORWARD_LIST_TCC 1
32 
33 namespace std _GLIBCXX_VISIBILITY(default)
34 {
35 _GLIBCXX_BEGIN_NAMESPACE_VERSION
36 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
37 
38  template<typename _Tp, typename _Alloc>
39  _Fwd_list_base<_Tp, _Alloc>::
40  _Fwd_list_base(_Fwd_list_base&& __lst, _Node_alloc_type&& __a)
41  : _M_impl(std::move(__a))
42  {
43  if (__lst._M_get_Node_allocator() == _M_get_Node_allocator())
44  this->_M_impl._M_head = std::move(__lst._M_impl._M_head);
45  }
46 
47  template<typename _Tp, typename _Alloc>
48  template<typename... _Args>
49  auto
50  _Fwd_list_base<_Tp, _Alloc>::
51  _M_insert_after(const_iterator __pos, _Args&&... __args)
52  -> _Base_ptr
53  {
54  auto __to = __pos._M_const_cast()._M_node;
55  _Node_ptr __thing = _M_create_node(std::forward<_Args>(__args)...);
56  __thing->_M_next = __to->_M_next;
57  __to->_M_next = __thing->_M_base_ptr();
58  return __to->_M_next;
59  }
60 
61  template<typename _Tp, typename _Alloc>
62  auto
63  _Fwd_list_base<_Tp, _Alloc>::
64  _M_erase_after(_Base_ptr __pos)
65  -> _Base_ptr
66  {
67  auto& __curr = static_cast<_Node&>(*__pos->_M_next);
68  __pos->_M_next = __curr._M_next;
69  _M_destroy_node(__curr._M_node_ptr());
70  return __pos->_M_next;
71  }
72 
73  template<typename _Tp, typename _Alloc>
74  auto
75  _Fwd_list_base<_Tp, _Alloc>::
76  _M_erase_after(_Base_ptr __pos, _Base_ptr __last)
77  -> _Base_ptr
78  {
79  _Base_ptr __curr = __pos->_M_next;
80  while (__curr != __last)
81  {
82  auto& __node = static_cast<_Node&>(*__curr);
83  __curr = __curr->_M_next;
84  _M_destroy_node(__node._M_node_ptr());
85  }
86  __pos->_M_next = __last;
87  return __last;
88  }
89 
90  // Called by the range constructor to implement [23.3.4.2]/9
91  template<typename _Tp, typename _Alloc>
92  template<typename _InputIterator>
93  void
94  forward_list<_Tp, _Alloc>::
95  _M_range_initialize(_InputIterator __first, _InputIterator __last)
96  {
97  auto __to = this->_M_impl._M_head._M_base_ptr();
98  for (; __first != __last; ++__first)
99  {
100  __to->_M_next = this->_M_create_node(*__first)->_M_base_ptr();
101  __to = __to->_M_next;
102  }
103  }
104 
105  // Called by forward_list(n,v,a).
106  template<typename _Tp, typename _Alloc>
107  void
108  forward_list<_Tp, _Alloc>::
109  _M_fill_initialize(size_type __n, const value_type& __value)
110  {
111  auto __to = this->_M_impl._M_head._M_base_ptr();
112  for (; __n; --__n)
113  {
114  __to->_M_next = this->_M_create_node(__value)->_M_base_ptr();
115  __to = __to->_M_next;
116  }
117  }
118 
119  template<typename _Tp, typename _Alloc>
120  void
121  forward_list<_Tp, _Alloc>::
122  _M_default_initialize(size_type __n)
123  {
124  auto __to = this->_M_impl._M_head._M_base_ptr();
125  for (; __n; --__n)
126  {
127  __to->_M_next = this->_M_create_node()->_M_base_ptr();
128  __to = __to->_M_next;
129  }
130  }
131 
132  template<typename _Tp, typename _Alloc>
133  forward_list<_Tp, _Alloc>&
135  operator=(const forward_list& __list)
136  {
137  if (std::__addressof(__list) != this)
138  {
139  if (_Node_alloc_traits::_S_propagate_on_copy_assign())
140  {
141  auto& __this_alloc = this->_M_get_Node_allocator();
142  auto& __that_alloc = __list._M_get_Node_allocator();
143  if (!_Node_alloc_traits::_S_always_equal()
144  && __this_alloc != __that_alloc)
145  {
146  // replacement allocator cannot free existing storage
147  clear();
148  }
149  std::__alloc_on_copy(__this_alloc, __that_alloc);
150  }
151  assign(__list.cbegin(), __list.cend());
152  }
153  return *this;
154  }
155 
156  template<typename _Tp, typename _Alloc>
157  void
159  _M_default_insert_after(const_iterator __pos, size_type __n)
160  {
161  const_iterator __saved_pos = __pos;
162  __try
163  {
164  for (; __n; --__n)
165  __pos = emplace_after(__pos);
166  }
167  __catch(...)
168  {
169  erase_after(__saved_pos, ++__pos);
170  __throw_exception_again;
171  }
172  }
173 
174  template<typename _Tp, typename _Alloc>
175  void
177  resize(size_type __sz)
178  {
179  iterator __k = before_begin();
180 
181  size_type __len = 0;
182  while (__k._M_next() != end() && __len < __sz)
183  {
184  ++__k;
185  ++__len;
186  }
187  if (__len == __sz)
188  erase_after(__k, end());
189  else
190  _M_default_insert_after(__k, __sz - __len);
191  }
192 
193  template<typename _Tp, typename _Alloc>
194  void
196  resize(size_type __sz, const value_type& __val)
197  {
198  iterator __k = before_begin();
199 
200  size_type __len = 0;
201  while (__k._M_next() != end() && __len < __sz)
202  {
203  ++__k;
204  ++__len;
205  }
206  if (__len == __sz)
207  erase_after(__k, end());
208  else
209  insert_after(__k, __sz - __len, __val);
210  }
211 
212  template<typename _Tp, typename _Alloc>
213  typename forward_list<_Tp, _Alloc>::iterator
215  _M_splice_after(const_iterator __pos,
216  const_iterator __before, const_iterator __last)
217  {
218  auto __tmp = __pos._M_const_cast()._M_node;
219  auto __b = __before._M_const_cast()._M_node;
220  auto __end = __b;
221 
222  while (__end && __end->_M_next != __last._M_node)
223  __end = __end->_M_next;
224 
225  if (__b != __end)
226  return iterator(__tmp->_M_transfer_after(__b, __end));
227  else
228  return iterator(__tmp);
229  }
230 
231  template<typename _Tp, typename _Alloc>
232  void
234  splice_after(const_iterator __pos, forward_list&&,
235  const_iterator __i) noexcept
236  {
237  const_iterator __j = __i;
238  ++__j;
239 
240  if (__pos == __i || __pos == __j)
241  return;
242 
243  auto __tmp = __pos._M_const_cast()._M_node;
244  __tmp->_M_transfer_after(__i._M_const_cast()._M_node,
245  __j._M_const_cast()._M_node);
246  }
247 
248  template<typename _Tp, typename _Alloc>
249  typename forward_list<_Tp, _Alloc>::iterator
251  insert_after(const_iterator __pos, size_type __n, const _Tp& __val)
252  {
253  if (__n)
254  {
255  forward_list __tmp(__n, __val, get_allocator());
256  return _M_splice_after(__pos, __tmp.before_begin(), __tmp.end());
257  }
258  else
259  return __pos._M_const_cast();
260  }
261 
262  template<typename _Tp, typename _Alloc>
263  template<typename _InputIterator, typename>
264  typename forward_list<_Tp, _Alloc>::iterator
266  insert_after(const_iterator __pos,
267  _InputIterator __first, _InputIterator __last)
268  {
269  forward_list __tmp(__first, __last, get_allocator());
270  if (!__tmp.empty())
271  return _M_splice_after(__pos, __tmp.before_begin(), __tmp.end());
272  else
273  return __pos._M_const_cast();
274  }
275 
276 #if __cplusplus > 201703L
277 # define _GLIBCXX20_ONLY(__expr) __expr
278 #else
279 # define _GLIBCXX20_ONLY(__expr)
280 #endif
281 
282  template<typename _Tp, typename _Alloc>
283  auto
285  remove(const _Tp& __val) -> __remove_return_type
286  {
287  size_type __removed __attribute__((__unused__)) = 0;
288  forward_list __to_destroy(get_allocator());
289 
290  auto __prev_it = cbefore_begin();
291  while (auto __tmp = __prev_it._M_node->_M_next)
292  if (*static_cast<_Node&>(*__tmp)._M_valptr() == __val)
293  {
294  __to_destroy.splice_after(__to_destroy.cbefore_begin(),
295  *this, __prev_it);
296  _GLIBCXX20_ONLY( __removed++ );
297  }
298  else
299  ++__prev_it;
300 
301  return _GLIBCXX20_ONLY( __removed );
302  }
303 
304  template<typename _Tp, typename _Alloc>
305  template<typename _Pred>
306  auto
308  remove_if(_Pred __pred) -> __remove_return_type
309  {
310  size_type __removed __attribute__((__unused__)) = 0;
311  forward_list __to_destroy(get_allocator());
312 
313  auto __prev_it = cbefore_begin();
314  while (auto __tmp = __prev_it._M_node->_M_next)
315  if (__pred(*static_cast<_Node&>(*__tmp)._M_valptr()))
316  {
317  __to_destroy.splice_after(__to_destroy.cbefore_begin(),
318  *this, __prev_it);
319  _GLIBCXX20_ONLY( __removed++ );
320  }
321  else
322  ++__prev_it;
323 
324  return _GLIBCXX20_ONLY( __removed );
325  }
326 
327  template<typename _Tp, typename _Alloc>
328  template<typename _BinPred>
329  auto
330  forward_list<_Tp, _Alloc>::
331  unique(_BinPred __binary_pred) -> __remove_return_type
332  {
333  iterator __first = begin();
334  iterator __last = end();
335  if (__first == __last)
336  return _GLIBCXX20_ONLY(0);
337 
338  forward_list __to_destroy(get_allocator());
339  size_type __removed __attribute__((__unused__)) = 0;
340  iterator __next = __first;
341  while (++__next != __last)
342  {
343  if (__binary_pred(*__first, *__next))
344  {
345  __to_destroy.splice_after(__to_destroy.cbefore_begin(),
346  *this, __first);
347  _GLIBCXX20_ONLY( __removed++ );
348  }
349  else
350  __first = __next;
351  __next = __first;
352  }
353 
354  return _GLIBCXX20_ONLY( __removed );
355  }
356 
357 #undef _GLIBCXX20_ONLY
358 
359  template<typename _Tp, typename _Alloc>
360  template<typename _Comp>
361  void
363  merge(forward_list&& __list, _Comp __comp)
364  {
365  // _GLIBCXX_RESOLVE_LIB_DEFECTS
366  // 3088. forward_list::merge behavior unclear when passed *this
367  if (std::__addressof(__list) == this)
368  return;
369 
370  using _Base_ptr = typename _Node::_Base_ptr;
371 
372  _Base_ptr __node = this->_M_impl._M_head._M_base_ptr();
373  _Base_ptr __other = __list._M_impl._M_head._M_base_ptr();
374  while (__node->_M_next && __other->_M_next)
375  {
376  auto& __l = static_cast<_Node&>(*__other->_M_next);
377  auto& __r = static_cast<_Node&>(*__node->_M_next);
378  if (__comp(*__l._M_valptr(), *__r._M_valptr()))
379  __node->_M_transfer_after(__other, __other->_M_next);
380  __node = __node->_M_next;
381  }
382 
383  if (__list._M_impl._M_head._M_next)
384  *__node = std::move(__list._M_impl._M_head);
385  }
386 
387  template<typename _Tp, typename _Alloc>
388  bool
390  const forward_list<_Tp, _Alloc>& __ly)
391  {
392  // We don't have size() so we need to walk through both lists
393  // making sure both iterators are valid.
394  auto __ix = __lx.cbegin();
395  auto __iy = __ly.cbegin();
396  while (__ix != __lx.cend() && __iy != __ly.cend())
397  {
398  if (!(*__ix == *__iy))
399  return false;
400  ++__ix;
401  ++__iy;
402  }
403  if (__ix == __lx.cend() && __iy == __ly.cend())
404  return true;
405  else
406  return false;
407  }
408 
409  template<typename _Tp, class _Alloc>
410  template<typename _Comp>
411  void
413  sort(_Comp __comp)
414  {
415  if (empty())
416  return;
417 
418  using _Base_ptr = typename _Node::_Base_ptr;
419 
420  // If `next' is nullptr, return immediately.
421  _Base_ptr __list = this->_M_impl._M_head._M_next;
422 
423  unsigned long __insize = 1;
424 
425  while (1)
426  {
427  _Base_ptr __p = __list;
428  __list = nullptr;
429  _Base_ptr __tail = nullptr;
430 
431  // Count number of merges we do in this pass.
432  unsigned long __nmerges = 0;
433 
434  while (__p)
435  {
436  ++__nmerges;
437  // There exists a merge to be done.
438  // Step `insize' places along from p.
439  _Base_ptr __q = __p;
440  unsigned long __psize = 0;
441  for (unsigned long __i = 0; __i < __insize; ++__i)
442  {
443  ++__psize;
444  __q = __q->_M_next;
445  if (!__q)
446  break;
447  }
448 
449  // If q hasn't fallen off end, we have two lists to merge.
450  unsigned long __qsize = __insize;
451 
452  // Now we have two lists; merge them.
453  while (__psize > 0 || (__qsize > 0 && __q))
454  {
455  // Decide whether next node of merge comes from p or q.
456  _Base_ptr __e;
457  if (__psize == 0)
458  {
459  // p is empty; e must come from q.
460  __e = __q;
461  __q = __q->_M_next;
462  --__qsize;
463  }
464  else if (__qsize == 0 || !__q)
465  {
466  // q is empty; e must come from p.
467  __e = __p;
468  __p = __p->_M_next;
469  --__psize;
470  }
471  else if (!__comp(*static_cast<_Node&>(*__q)._M_valptr(),
472  *static_cast<_Node&>(*__p)._M_valptr()))
473  {
474  // First node of q is not lower; e must come from p.
475  __e = __p;
476  __p = __p->_M_next;
477  --__psize;
478  }
479  else
480  {
481  // First node of q is lower; e must come from q.
482  __e = __q;
483  __q = __q->_M_next;
484  --__qsize;
485  }
486 
487  // Add the next node to the merged list.
488  if (__tail)
489  __tail->_M_next = __e;
490  else
491  __list = __e;
492  __tail = __e;
493  }
494 
495  // Now p has stepped `insize' places along, and q has too.
496  __p = __q;
497  }
498  __tail->_M_next = nullptr;
499 
500  // If we have done only one merge, we're finished.
501  // Allow for nmerges == 0, the empty list case.
502  if (__nmerges <= 1)
503  {
504  this->_M_impl._M_head._M_next = __list;
505  return;
506  }
507 
508  // Otherwise repeat, merging lists twice the size.
509  __insize *= 2;
510  }
511  }
512 
513 _GLIBCXX_END_NAMESPACE_CONTAINER
514 _GLIBCXX_END_NAMESPACE_VERSION
515 } // namespace std
516 
517 #endif /* _FORWARD_LIST_TCC */
bool operator==(const error_code &__lhs, const error_code &__rhs) noexcept
Definition: system_error:451
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition: move.h:52
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:138
ISO C++ entities toplevel namespace is std.
constexpr auto empty(const _Container &__cont) noexcept(noexcept(__cont.empty())) -> decltype(__cont.empty())
Return whether a container is empty.
Definition: range_access.h:294
constexpr const _Tp * begin(initializer_list< _Tp > __ils) noexcept
Return an iterator pointing to the first element of the initializer_list.
constexpr const _Tp * end(initializer_list< _Tp > __ils) noexcept
Return an iterator pointing to one past the last element of the initializer_list.
A standard container with linear time access to elements, and fixed time insertion/deletion at any po...
Definition: forward_list.h:768
iterator before_begin() noexcept
iterator end() noexcept
void splice_after(const_iterator __pos, forward_list &&__list) noexcept
Insert contents of another forward_list.
const_iterator cbefore_begin() const noexcept
const_iterator cend() const noexcept
bool empty() const noexcept
const_iterator cbegin() const noexcept
Common iterator class.