1// <forward_list.h> -*- C++ -*-
2
3// Copyright (C) 2008-2018 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 bits/forward_list.h
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_H
31#define _FORWARD_LIST_H 1
32
33#pragma GCC system_header
34
35#include <initializer_list>
36#include <bits/stl_iterator_base_types.h>
37#include <bits/stl_iterator.h>
38#include <bits/stl_algobase.h>
39#include <bits/stl_function.h>
40#include <bits/allocator.h>
41#include <ext/alloc_traits.h>
42#include <ext/aligned_buffer.h>
43
44namespace std _GLIBCXX_VISIBILITY(default)
45{
46_GLIBCXX_BEGIN_NAMESPACE_VERSION
47_GLIBCXX_BEGIN_NAMESPACE_CONTAINER
48
49 /**
50 * @brief A helper basic node class for %forward_list.
51 * This is just a linked list with nothing inside it.
52 * There are purely list shuffling utility methods here.
53 */
54 struct _Fwd_list_node_base
55 {
56 _Fwd_list_node_base() = default;
57 _Fwd_list_node_base(_Fwd_list_node_base&& __x) noexcept
58 : _M_next(__x._M_next)
59 { __x._M_next = nullptr; }
60
61 _Fwd_list_node_base(const _Fwd_list_node_base&) = delete;
62 _Fwd_list_node_base& operator=(const _Fwd_list_node_base&) = delete;
63
64 _Fwd_list_node_base&
65 operator=(_Fwd_list_node_base&& __x) noexcept
66 {
67 _M_next = __x._M_next;
68 __x._M_next = nullptr;
69 return *this;
70 }
71
72 _Fwd_list_node_base* _M_next = nullptr;
73
74 _Fwd_list_node_base*
75 _M_transfer_after(_Fwd_list_node_base* __begin,
76 _Fwd_list_node_base* __end) noexcept
77 {
78 _Fwd_list_node_base* __keep = __begin->_M_next;
79 if (__end)
80 {
81 __begin->_M_next = __end->_M_next;
82 __end->_M_next = _M_next;
83 }
84 else
85 __begin->_M_next = nullptr;
86 _M_next = __keep;
87 return __end;
88 }
89
90 void
91 _M_reverse_after() noexcept
92 {
93 _Fwd_list_node_base* __tail = _M_next;
94 if (!__tail)
95 return;
96 while (_Fwd_list_node_base* __temp = __tail->_M_next)
97 {
98 _Fwd_list_node_base* __keep = _M_next;
99 _M_next = __temp;
100 __tail->_M_next = __temp->_M_next;
101 _M_next->_M_next = __keep;
102 }
103 }
104 };
105
106 /**
107 * @brief A helper node class for %forward_list.
108 * This is just a linked list with uninitialized storage for a
109 * data value in each node.
110 * There is a sorting utility method.
111 */
112 template<typename _Tp>
113 struct _Fwd_list_node
114 : public _Fwd_list_node_base
115 {
116 _Fwd_list_node() = default;
117
118 __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
119
120 _Tp*
121 _M_valptr() noexcept
122 { return _M_storage._M_ptr(); }
123
124 const _Tp*
125 _M_valptr() const noexcept
126 { return _M_storage._M_ptr(); }
127 };
128
129 /**
130 * @brief A forward_list::iterator.
131 *
132 * All the functions are op overloads.
133 */
134 template<typename _Tp>
135 struct _Fwd_list_iterator
136 {
137 typedef _Fwd_list_iterator<_Tp> _Self;
138 typedef _Fwd_list_node<_Tp> _Node;
139
140 typedef _Tp value_type;
141 typedef _Tp* pointer;
142 typedef _Tp& reference;
143 typedef ptrdiff_t difference_type;
144 typedef std::forward_iterator_tag iterator_category;
145
146 _Fwd_list_iterator() noexcept
147 : _M_node() { }
148
149 explicit
150 _Fwd_list_iterator(_Fwd_list_node_base* __n) noexcept
151 : _M_node(__n) { }
152
153 reference
154 operator*() const noexcept
155 { return *static_cast<_Node*>(this->_M_node)->_M_valptr(); }
156
157 pointer
158 operator->() const noexcept
159 { return static_cast<_Node*>(this->_M_node)->_M_valptr(); }
160
161 _Self&
162 operator++() noexcept
163 {
164 _M_node = _M_node->_M_next;
165 return *this;
166 }
167
168 _Self
169 operator++(int) noexcept
170 {
171 _Self __tmp(*this);
172 _M_node = _M_node->_M_next;
173 return __tmp;
174 }
175
176 bool
177 operator==(const _Self& __x) const noexcept
178 { return _M_node == __x._M_node; }
179
180 bool
181 operator!=(const _Self& __x) const noexcept
182 { return _M_node != __x._M_node; }
183
184 _Self
185 _M_next() const noexcept
186 {
187 if (_M_node)
188 return _Fwd_list_iterator(_M_node->_M_next);
189 else
190 return _Fwd_list_iterator(nullptr);
191 }
192
193 _Fwd_list_node_base* _M_node;
194 };
195
196 /**
197 * @brief A forward_list::const_iterator.
198 *
199 * All the functions are op overloads.
200 */
201 template<typename _Tp>
202 struct _Fwd_list_const_iterator
203 {
204 typedef _Fwd_list_const_iterator<_Tp> _Self;
205 typedef const _Fwd_list_node<_Tp> _Node;
206 typedef _Fwd_list_iterator<_Tp> iterator;
207
208 typedef _Tp value_type;
209 typedef const _Tp* pointer;
210 typedef const _Tp& reference;
211 typedef ptrdiff_t difference_type;
212 typedef std::forward_iterator_tag iterator_category;
213
214 _Fwd_list_const_iterator() noexcept
215 : _M_node() { }
216
217 explicit
218 _Fwd_list_const_iterator(const _Fwd_list_node_base* __n) noexcept
219 : _M_node(__n) { }
220
221 _Fwd_list_const_iterator(const iterator& __iter) noexcept
222 : _M_node(__iter._M_node) { }
223
224 reference
225 operator*() const noexcept
226 { return *static_cast<_Node*>(this->_M_node)->_M_valptr(); }
227
228 pointer
229 operator->() const noexcept
230 { return static_cast<_Node*>(this->_M_node)->_M_valptr(); }
231
232 _Self&
233 operator++() noexcept
234 {
235 _M_node = _M_node->_M_next;
236 return *this;
237 }
238
239 _Self
240 operator++(int) noexcept
241 {
242 _Self __tmp(*this);
243 _M_node = _M_node->_M_next;
244 return __tmp;
245 }
246
247 bool
248 operator==(const _Self& __x) const noexcept
249 { return _M_node == __x._M_node; }
250
251 bool
252 operator!=(const _Self& __x) const noexcept
253 { return _M_node != __x._M_node; }
254
255 _Self
256 _M_next() const noexcept
257 {
258 if (this->_M_node)
259 return _Fwd_list_const_iterator(_M_node->_M_next);
260 else
261 return _Fwd_list_const_iterator(nullptr);
262 }
263
264 const _Fwd_list_node_base* _M_node;
265 };
266
267 /**
268 * @brief Forward list iterator equality comparison.
269 */
270 template<typename _Tp>
271 inline bool
272 operator==(const _Fwd_list_iterator<_Tp>& __x,
273 const _Fwd_list_const_iterator<_Tp>& __y) noexcept
274 { return __x._M_node == __y._M_node; }
275
276 /**
277 * @brief Forward list iterator inequality comparison.
278 */
279 template<typename _Tp>
280 inline bool
281 operator!=(const _Fwd_list_iterator<_Tp>& __x,
282 const _Fwd_list_const_iterator<_Tp>& __y) noexcept
283 { return __x._M_node != __y._M_node; }
284
285 /**
286 * @brief Base class for %forward_list.
287 */
288 template<typename _Tp, typename _Alloc>
289 struct _Fwd_list_base
290 {
291 protected:
292 typedef __alloc_rebind<_Alloc, _Fwd_list_node<_Tp>> _Node_alloc_type;
293 typedef __gnu_cxx::__alloc_traits<_Node_alloc_type> _Node_alloc_traits;
294
295 struct _Fwd_list_impl
296 : public _Node_alloc_type
297 {
298 _Fwd_list_node_base _M_head;
299
300 _Fwd_list_impl()
301 noexcept(is_nothrow_default_constructible<_Node_alloc_type>::value)
302 : _Node_alloc_type(), _M_head()
303 { }
304
305 _Fwd_list_impl(_Fwd_list_impl&&) = default;
306
307 _Fwd_list_impl(_Fwd_list_impl&& __fl, _Node_alloc_type&& __a)
308 : _Node_alloc_type(std::move(__a)), _M_head(std::move(__fl._M_head))
309 { }
310
311 _Fwd_list_impl(_Node_alloc_type&& __a)
312 : _Node_alloc_type(std::move(__a)), _M_head()
313 { }
314 };
315
316 _Fwd_list_impl _M_impl;
317
318 public:
319 typedef _Fwd_list_iterator<_Tp> iterator;
320 typedef _Fwd_list_const_iterator<_Tp> const_iterator;
321 typedef _Fwd_list_node<_Tp> _Node;
322
323 _Node_alloc_type&
324 _M_get_Node_allocator() noexcept
325 { return this->_M_impl; }
326
327 const _Node_alloc_type&
328 _M_get_Node_allocator() const noexcept
329 { return this->_M_impl; }
330
331 _Fwd_list_base() = default;
332
333 _Fwd_list_base(_Node_alloc_type&& __a)
334 : _M_impl(std::move(__a)) { }
335
336 // When allocators are always equal.
337 _Fwd_list_base(_Fwd_list_base&& __lst, _Node_alloc_type&& __a,
338 std::true_type)
339 : _M_impl(std::move(__lst._M_impl), std::move(__a))
340 { }
341
342 // When allocators are not always equal.
343 _Fwd_list_base(_Fwd_list_base&& __lst, _Node_alloc_type&& __a);
344
345 _Fwd_list_base(_Fwd_list_base&&) = default;
346
347 ~_Fwd_list_base()
348 { _M_erase_after(&_M_impl._M_head, nullptr); }
349
350 protected:
351 _Node*
352 _M_get_node()
353 {
354 auto __ptr = _Node_alloc_traits::allocate(_M_get_Node_allocator(), 1);
355 return std::__to_address(__ptr);
356 }
357
358 template<typename... _Args>
359 _Node*
360 _M_create_node(_Args&&... __args)
361 {
362 _Node* __node = this->_M_get_node();
363 __try
364 {
365 ::new ((void*)__node) _Node;
366 _Node_alloc_traits::construct(_M_get_Node_allocator(),
367 __node->_M_valptr(),
368 std::forward<_Args>(__args)...);
369 }
370 __catch(...)
371 {
372 this->_M_put_node(__node);
373 __throw_exception_again;
374 }
375 return __node;
376 }
377
378 template<typename... _Args>
379 _Fwd_list_node_base*
380 _M_insert_after(const_iterator __pos, _Args&&... __args);
381
382 void
383 _M_put_node(_Node* __p)
384 {
385 typedef typename _Node_alloc_traits::pointer _Ptr;
386 auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__p);
387 _Node_alloc_traits::deallocate(_M_get_Node_allocator(), __ptr, 1);
388 }
389
390 _Fwd_list_node_base*
391 _M_erase_after(_Fwd_list_node_base* __pos);
392
393 _Fwd_list_node_base*
394 _M_erase_after(_Fwd_list_node_base* __pos,
395 _Fwd_list_node_base* __last);
396 };
397
398 /**
399 * @brief A standard container with linear time access to elements,
400 * and fixed time insertion/deletion at any point in the sequence.
401 *
402 * @ingroup sequences
403 *
404 * @tparam _Tp Type of element.
405 * @tparam _Alloc Allocator type, defaults to allocator<_Tp>.
406 *
407 * Meets the requirements of a <a href="tables.html#65">container</a>, a
408 * <a href="tables.html#67">sequence</a>, including the
409 * <a href="tables.html#68">optional sequence requirements</a> with the
410 * %exception of @c at and @c operator[].
411 *
412 * This is a @e singly @e linked %list. Traversal up the
413 * %list requires linear time, but adding and removing elements (or
414 * @e nodes) is done in constant time, regardless of where the
415 * change takes place. Unlike std::vector and std::deque,
416 * random-access iterators are not provided, so subscripting ( @c
417 * [] ) access is not allowed. For algorithms which only need
418 * sequential access, this lack makes no difference.
419 *
420 * Also unlike the other standard containers, std::forward_list provides
421 * specialized algorithms %unique to linked lists, such as
422 * splicing, sorting, and in-place reversal.
423 */
424 template<typename _Tp, typename _Alloc = allocator<_Tp>>
425 class forward_list : private _Fwd_list_base<_Tp, _Alloc>
426 {
427 static_assert(is_same<typename remove_cv<_Tp>::type, _Tp>::value,
428 "std::forward_list must have a non-const, non-volatile value_type");
429#ifdef __STRICT_ANSI__
430 static_assert(is_same<typename _Alloc::value_type, _Tp>::value,
431 "std::forward_list must have the same value_type as its allocator");
432#endif
433
434 private:
435 typedef _Fwd_list_base<_Tp, _Alloc> _Base;
436 typedef _Fwd_list_node<_Tp> _Node;
437 typedef _Fwd_list_node_base _Node_base;
438 typedef typename _Base::_Node_alloc_type _Node_alloc_type;
439 typedef typename _Base::_Node_alloc_traits _Node_alloc_traits;
440 typedef allocator_traits<__alloc_rebind<_Alloc, _Tp>> _Alloc_traits;
441
442 public:
443 // types:
444 typedef _Tp value_type;
445 typedef typename _Alloc_traits::pointer pointer;
446 typedef typename _Alloc_traits::const_pointer const_pointer;
447 typedef value_type& reference;
448 typedef const value_type& const_reference;
449
450 typedef _Fwd_list_iterator<_Tp> iterator;
451 typedef _Fwd_list_const_iterator<_Tp> const_iterator;
452 typedef std::size_t size_type;
453 typedef std::ptrdiff_t difference_type;
454 typedef _Alloc allocator_type;
455
456 // 23.3.4.2 construct/copy/destroy:
457
458 /**
459 * @brief Creates a %forward_list with no elements.
460 */
461 forward_list() = default;
462
463 /**
464 * @brief Creates a %forward_list with no elements.
465 * @param __al An allocator object.
466 */
467 explicit
468 forward_list(const _Alloc& __al) noexcept
469 : _Base(_Node_alloc_type(__al))
470 { }
471
472 /**
473 * @brief Copy constructor with allocator argument.
474 * @param __list Input list to copy.
475 * @param __al An allocator object.
476 */
477 forward_list(const forward_list& __list, const _Alloc& __al)
478 : _Base(_Node_alloc_type(__al))
479 { _M_range_initialize(__list.begin(), __list.end()); }
480
481 private:
482 forward_list(forward_list&& __list, _Node_alloc_type&& __al,
483 false_type)
484 : _Base(std::move(__list), std::move(__al))
485 {
486 // If __list is not empty it means its allocator is not equal to __a,
487 // so we need to move from each element individually.
488 insert_after(cbefore_begin(),
489 std::__make_move_if_noexcept_iterator(__list.begin()),
490 std::__make_move_if_noexcept_iterator(__list.end()));
491 }
492
493 forward_list(forward_list&& __list, _Node_alloc_type&& __al,
494 true_type)
495 noexcept
496 : _Base(std::move(__list), _Node_alloc_type(__al), true_type{})
497 { }
498
499 public:
500 /**
501 * @brief Move constructor with allocator argument.
502 * @param __list Input list to move.
503 * @param __al An allocator object.
504 */
505 forward_list(forward_list&& __list, const _Alloc& __al)
506 noexcept(_Node_alloc_traits::_S_always_equal())
507 : forward_list(std::move(__list), _Node_alloc_type(__al),
508 typename _Node_alloc_traits::is_always_equal{})
509 { }
510
511 /**
512 * @brief Creates a %forward_list with default constructed elements.
513 * @param __n The number of elements to initially create.
514 * @param __al An allocator object.
515 *
516 * This constructor creates the %forward_list with @a __n default
517 * constructed elements.
518 */
519 explicit
520 forward_list(size_type __n, const _Alloc& __al = _Alloc())
521 : _Base(_Node_alloc_type(__al))
522 { _M_default_initialize(__n); }
523
524 /**
525 * @brief Creates a %forward_list with copies of an exemplar element.
526 * @param __n The number of elements to initially create.
527 * @param __value An element to copy.
528 * @param __al An allocator object.
529 *
530 * This constructor fills the %forward_list with @a __n copies of
531 * @a __value.
532 */
533 forward_list(size_type __n, const _Tp& __value,
534 const _Alloc& __al = _Alloc())
535 : _Base(_Node_alloc_type(__al))
536 { _M_fill_initialize(__n, __value); }
537
538 /**
539 * @brief Builds a %forward_list from a range.
540 * @param __first An input iterator.
541 * @param __last An input iterator.
542 * @param __al An allocator object.
543 *
544 * Create a %forward_list consisting of copies of the elements from
545 * [@a __first,@a __last). This is linear in N (where N is
546 * distance(@a __first,@a __last)).
547 */
548 template<typename _InputIterator,
549 typename = std::_RequireInputIter<_InputIterator>>
550 forward_list(_InputIterator __first, _InputIterator __last,
551 const _Alloc& __al = _Alloc())
552 : _Base(_Node_alloc_type(__al))
553 { _M_range_initialize(__first, __last); }
554
555 /**
556 * @brief The %forward_list copy constructor.
557 * @param __list A %forward_list of identical element and allocator
558 * types.
559 */
560 forward_list(const forward_list& __list)
561 : _Base(_Node_alloc_traits::_S_select_on_copy(
562 __list._M_get_Node_allocator()))
563 { _M_range_initialize(__list.begin(), __list.end()); }
564
565 /**
566 * @brief The %forward_list move constructor.
567 * @param __list A %forward_list of identical element and allocator
568 * types.
569 *
570 * The newly-created %forward_list contains the exact contents of the
571 * moved instance. The contents of the moved instance are a valid, but
572 * unspecified %forward_list.
573 */
574 forward_list(forward_list&&) = default;
575
576 /**
577 * @brief Builds a %forward_list from an initializer_list
578 * @param __il An initializer_list of value_type.
579 * @param __al An allocator object.
580 *
581 * Create a %forward_list consisting of copies of the elements
582 * in the initializer_list @a __il. This is linear in __il.size().
583 */
584 forward_list(std::initializer_list<_Tp> __il,
585 const _Alloc& __al = _Alloc())
586 : _Base(_Node_alloc_type(__al))
587 { _M_range_initialize(__il.begin(), __il.end()); }
588
589 /**
590 * @brief The forward_list dtor.
591 */
592 ~forward_list() noexcept
593 { }
594
595 /**
596 * @brief The %forward_list assignment operator.
597 * @param __list A %forward_list of identical element and allocator
598 * types.
599 *
600 * All the elements of @a __list are copied.
601 *
602 * Whether the allocator is copied depends on the allocator traits.
603 */
604 forward_list&
605 operator=(const forward_list& __list);
606
607 /**
608 * @brief The %forward_list move assignment operator.
609 * @param __list A %forward_list of identical element and allocator
610 * types.
611 *
612 * The contents of @a __list are moved into this %forward_list
613 * (without copying, if the allocators permit it).
614 *
615 * Afterwards @a __list is a valid, but unspecified %forward_list
616 *
617 * Whether the allocator is moved depends on the allocator traits.
618 */
619 forward_list&
620 operator=(forward_list&& __list)
621 noexcept(_Node_alloc_traits::_S_nothrow_move())
622 {
623 constexpr bool __move_storage =
624 _Node_alloc_traits::_S_propagate_on_move_assign()
625 || _Node_alloc_traits::_S_always_equal();
626 _M_move_assign(std::move(__list), __bool_constant<__move_storage>());
627 return *this;
628 }
629
630 /**
631 * @brief The %forward_list initializer list assignment operator.
632 * @param __il An initializer_list of value_type.
633 *
634 * Replace the contents of the %forward_list with copies of the
635 * elements in the initializer_list @a __il. This is linear in
636 * __il.size().
637 */
638 forward_list&
639 operator=(std::initializer_list<_Tp> __il)
640 {
641 assign(__il);
642 return *this;
643 }
644
645 /**
646 * @brief Assigns a range to a %forward_list.
647 * @param __first An input iterator.
648 * @param __last An input iterator.
649 *
650 * This function fills a %forward_list with copies of the elements
651 * in the range [@a __first,@a __last).
652 *
653 * Note that the assignment completely changes the %forward_list and
654 * that the number of elements of the resulting %forward_list is the
655 * same as the number of elements assigned.
656 */
657 template<typename _InputIterator,
658 typename = std::_RequireInputIter<_InputIterator>>
659 void
660 assign(_InputIterator __first, _InputIterator __last)
661 {
662 typedef is_assignable<_Tp, decltype(*__first)> __assignable;
663 _M_assign(__first, __last, __assignable());
664 }
665
666 /**
667 * @brief Assigns a given value to a %forward_list.
668 * @param __n Number of elements to be assigned.
669 * @param __val Value to be assigned.
670 *
671 * This function fills a %forward_list with @a __n copies of the
672 * given value. Note that the assignment completely changes the
673 * %forward_list, and that the resulting %forward_list has __n
674 * elements.
675 */
676 void
677 assign(size_type __n, const _Tp& __val)
678 { _M_assign_n(__n, __val, is_copy_assignable<_Tp>()); }
679
680 /**
681 * @brief Assigns an initializer_list to a %forward_list.
682 * @param __il An initializer_list of value_type.
683 *
684 * Replace the contents of the %forward_list with copies of the
685 * elements in the initializer_list @a __il. This is linear in
686 * il.size().
687 */
688 void
689 assign(std::initializer_list<_Tp> __il)
690 { assign(__il.begin(), __il.end()); }
691
692 /// Get a copy of the memory allocation object.
693 allocator_type
694 get_allocator() const noexcept
695 { return allocator_type(this->_M_get_Node_allocator()); }
696
697 // 23.3.4.3 iterators:
698
699 /**
700 * Returns a read/write iterator that points before the first element
701 * in the %forward_list. Iteration is done in ordinary element order.
702 */
703 iterator
704 before_begin() noexcept
705 { return iterator(&this->_M_impl._M_head); }
706
707 /**
708 * Returns a read-only (constant) iterator that points before the
709 * first element in the %forward_list. Iteration is done in ordinary
710 * element order.
711 */
712 const_iterator
713 before_begin() const noexcept
714 { return const_iterator(&this->_M_impl._M_head); }
715
716 /**
717 * Returns a read/write iterator that points to the first element
718 * in the %forward_list. Iteration is done in ordinary element order.
719 */
720 iterator
721 begin() noexcept
722 { return iterator(this->_M_impl._M_head._M_next); }
723
724 /**
725 * Returns a read-only (constant) iterator that points to the first
726 * element in the %forward_list. Iteration is done in ordinary
727 * element order.
728 */
729 const_iterator
730 begin() const noexcept
731 { return const_iterator(this->_M_impl._M_head._M_next); }
732
733 /**
734 * Returns a read/write iterator that points one past the last
735 * element in the %forward_list. Iteration is done in ordinary
736 * element order.
737 */
738 iterator
739 end() noexcept
740 { return iterator(nullptr); }
741
742 /**
743 * Returns a read-only iterator that points one past the last
744 * element in the %forward_list. Iteration is done in ordinary
745 * element order.
746 */
747 const_iterator
748 end() const noexcept
749 { return const_iterator(nullptr); }
750
751 /**
752 * Returns a read-only (constant) iterator that points to the
753 * first element in the %forward_list. Iteration is done in ordinary
754 * element order.
755 */
756 const_iterator
757 cbegin() const noexcept
758 { return const_iterator(this->_M_impl._M_head._M_next); }
759
760 /**
761 * Returns a read-only (constant) iterator that points before the
762 * first element in the %forward_list. Iteration is done in ordinary
763 * element order.
764 */
765 const_iterator
766 cbefore_begin() const noexcept
767 { return const_iterator(&this->_M_impl._M_head); }
768
769 /**
770 * Returns a read-only (constant) iterator that points one past
771 * the last element in the %forward_list. Iteration is done in
772 * ordinary element order.
773 */
774 const_iterator
775 cend() const noexcept
776 { return const_iterator(nullptr); }
777
778 /**
779 * Returns true if the %forward_list is empty. (Thus begin() would
780 * equal end().)
781 */
782 bool
783 empty() const noexcept
784 { return this->_M_impl._M_head._M_next == nullptr; }
785
786 /**
787 * Returns the largest possible number of elements of %forward_list.
788 */
789 size_type
790 max_size() const noexcept
791 { return _Node_alloc_traits::max_size(this->_M_get_Node_allocator()); }
792
793 // 23.3.4.4 element access:
794
795 /**
796 * Returns a read/write reference to the data at the first
797 * element of the %forward_list.
798 */
799 reference
800 front()
801 {
802 _Node* __front = static_cast<_Node*>(this->_M_impl._M_head._M_next);
803 return *__front->_M_valptr();
804 }
805
806 /**
807 * Returns a read-only (constant) reference to the data at the first
808 * element of the %forward_list.
809 */
810 const_reference
811 front() const
812 {
813 _Node* __front = static_cast<_Node*>(this->_M_impl._M_head._M_next);
814 return *__front->_M_valptr();
815 }
816
817 // 23.3.4.5 modiļ¬ers:
818
819 /**
820 * @brief Constructs object in %forward_list at the front of the
821 * list.
822 * @param __args Arguments.
823 *
824 * This function will insert an object of type Tp constructed
825 * with Tp(std::forward<Args>(args)...) at the front of the list
826 * Due to the nature of a %forward_list this operation can
827 * be done in constant time, and does not invalidate iterators
828 * and references.
829 */
830 template<typename... _Args>
831#if __cplusplus > 201402L
832 reference
833#else
834 void
835#endif
836 emplace_front(_Args&&... __args)
837 {
838 this->_M_insert_after(cbefore_begin(),
839 std::forward<_Args>(__args)...);
840#if __cplusplus > 201402L
841 return front();
842#endif
843 }
844
845 /**
846 * @brief Add data to the front of the %forward_list.
847 * @param __val Data to be added.
848 *
849 * This is a typical stack operation. The function creates an
850 * element at the front of the %forward_list and assigns the given
851 * data to it. Due to the nature of a %forward_list this operation
852 * can be done in constant time, and does not invalidate iterators
853 * and references.
854 */
855 void
856 push_front(const _Tp& __val)
857 { this->_M_insert_after(cbefore_begin(), __val); }
858
859 /**
860 *
861 */
862 void
863 push_front(_Tp&& __val)
864 { this->_M_insert_after(cbefore_begin(), std::move(__val)); }
865
866 /**
867 * @brief Removes first element.
868 *
869 * This is a typical stack operation. It shrinks the %forward_list
870 * by one. Due to the nature of a %forward_list this operation can
871 * be done in constant time, and only invalidates iterators/references
872 * to the element being removed.
873 *
874 * Note that no data is returned, and if the first element's data
875 * is needed, it should be retrieved before pop_front() is
876 * called.
877 */
878 void
879 pop_front()
880 { this->_M_erase_after(&this->_M_impl._M_head); }
881
882 /**
883 * @brief Constructs object in %forward_list after the specified
884 * iterator.
885 * @param __pos A const_iterator into the %forward_list.
886 * @param __args Arguments.
887 * @return An iterator that points to the inserted data.
888 *
889 * This function will insert an object of type T constructed
890 * with T(std::forward<Args>(args)...) after the specified
891 * location. Due to the nature of a %forward_list this operation can
892 * be done in constant time, and does not invalidate iterators
893 * and references.
894 */
895 template<typename... _Args>
896 iterator
897 emplace_after(const_iterator __pos, _Args&&... __args)
898 { return iterator(this->_M_insert_after(__pos,
899 std::forward<_Args>(__args)...)); }
900
901 /**
902 * @brief Inserts given value into %forward_list after specified
903 * iterator.
904 * @param __pos An iterator into the %forward_list.
905 * @param __val Data to be inserted.
906 * @return An iterator that points to the inserted data.
907 *
908 * This function will insert a copy of the given value after
909 * the specified location. Due to the nature of a %forward_list this
910 * operation can be done in constant time, and does not
911 * invalidate iterators and references.
912 */
913 iterator
914 insert_after(const_iterator __pos, const _Tp& __val)
915 { return iterator(this->_M_insert_after(__pos, __val)); }
916
917 /**
918 *
919 */
920 iterator
921 insert_after(const_iterator __pos, _Tp&& __val)
922 { return iterator(this->_M_insert_after(__pos, std::move(__val))); }
923
924 /**
925 * @brief Inserts a number of copies of given data into the
926 * %forward_list.
927 * @param __pos An iterator into the %forward_list.
928 * @param __n Number of elements to be inserted.
929 * @param __val Data to be inserted.
930 * @return An iterator pointing to the last inserted copy of
931 * @a val or @a pos if @a n == 0.
932 *
933 * This function will insert a specified number of copies of the
934 * given data after the location specified by @a pos.
935 *
936 * This operation is linear in the number of elements inserted and
937 * does not invalidate iterators and references.
938 */
939 iterator
940 insert_after(const_iterator __pos, size_type __n, const _Tp& __val);
941
942 /**
943 * @brief Inserts a range into the %forward_list.
944 * @param __pos An iterator into the %forward_list.
945 * @param __first An input iterator.
946 * @param __last An input iterator.
947 * @return An iterator pointing to the last inserted element or
948 * @a __pos if @a __first == @a __last.
949 *
950 * This function will insert copies of the data in the range
951 * [@a __first,@a __last) into the %forward_list after the
952 * location specified by @a __pos.
953 *
954 * This operation is linear in the number of elements inserted and
955 * does not invalidate iterators and references.
956 */
957 template<typename _InputIterator,
958 typename = std::_RequireInputIter<_InputIterator>>
959 iterator
960 insert_after(const_iterator __pos,
961 _InputIterator __first, _InputIterator __last);
962
963 /**
964 * @brief Inserts the contents of an initializer_list into
965 * %forward_list after the specified iterator.
966 * @param __pos An iterator into the %forward_list.
967 * @param __il An initializer_list of value_type.
968 * @return An iterator pointing to the last inserted element
969 * or @a __pos if @a __il is empty.
970 *
971 * This function will insert copies of the data in the
972 * initializer_list @a __il into the %forward_list before the location
973 * specified by @a __pos.
974 *
975 * This operation is linear in the number of elements inserted and
976 * does not invalidate iterators and references.
977 */
978 iterator
979 insert_after(const_iterator __pos, std::initializer_list<_Tp> __il)
980 { return insert_after(__pos, __il.begin(), __il.end()); }
981
982 /**
983 * @brief Removes the element pointed to by the iterator following
984 * @c pos.
985 * @param __pos Iterator pointing before element to be erased.
986 * @return An iterator pointing to the element following the one
987 * that was erased, or end() if no such element exists.
988 *
989 * This function will erase the element at the given position and
990 * thus shorten the %forward_list by one.
991 *
992 * Due to the nature of a %forward_list this operation can be done
993 * in constant time, and only invalidates iterators/references to
994 * the element being removed. The user is also cautioned that
995 * this function only erases the element, and that if the element
996 * is itself a pointer, the pointed-to memory is not touched in
997 * any way. Managing the pointer is the user's responsibility.
998 */
999 iterator
1000 erase_after(const_iterator __pos)
1001 { return iterator(this->_M_erase_after(const_cast<_Node_base*>
1002 (__pos._M_node))); }
1003
1004 /**
1005 * @brief Remove a range of elements.
1006 * @param __pos Iterator pointing before the first element to be
1007 * erased.
1008 * @param __last Iterator pointing to one past the last element to be
1009 * erased.
1010 * @return @ __last.
1011 *
1012 * This function will erase the elements in the range
1013 * @a (__pos,__last) and shorten the %forward_list accordingly.
1014 *
1015 * This operation is linear time in the size of the range and only
1016 * invalidates iterators/references to the element being removed.
1017 * The user is also cautioned that this function only erases the
1018 * elements, and that if the elements themselves are pointers, the
1019 * pointed-to memory is not touched in any way. Managing the pointer
1020 * is the user's responsibility.
1021 */
1022 iterator
1023 erase_after(const_iterator __pos, const_iterator __last)
1024 { return iterator(this->_M_erase_after(const_cast<_Node_base*>
1025 (__pos._M_node),
1026 const_cast<_Node_base*>
1027 (__last._M_node))); }
1028
1029 /**
1030 * @brief Swaps data with another %forward_list.
1031 * @param __list A %forward_list of the same element and allocator
1032 * types.
1033 *
1034 * This exchanges the elements between two lists in constant
1035 * time. Note that the global std::swap() function is
1036 * specialized such that std::swap(l1,l2) will feed to this
1037 * function.
1038 *
1039 * Whether the allocators are swapped depends on the allocator traits.
1040 */
1041 void
1042 swap(forward_list& __list) noexcept
1043 {
1044 std::swap(this->_M_impl._M_head._M_next,
1045 __list._M_impl._M_head._M_next);
1046 _Node_alloc_traits::_S_on_swap(this->_M_get_Node_allocator(),
1047 __list._M_get_Node_allocator());
1048 }
1049
1050 /**
1051 * @brief Resizes the %forward_list to the specified number of
1052 * elements.
1053 * @param __sz Number of elements the %forward_list should contain.
1054 *
1055 * This function will %resize the %forward_list to the specified
1056 * number of elements. If the number is smaller than the
1057 * %forward_list's current number of elements the %forward_list
1058 * is truncated, otherwise the %forward_list is extended and the
1059 * new elements are default constructed.
1060 */
1061 void
1062 resize(size_type __sz);
1063
1064 /**
1065 * @brief Resizes the %forward_list to the specified number of
1066 * elements.
1067 * @param __sz Number of elements the %forward_list should contain.
1068 * @param __val Data with which new elements should be populated.
1069 *
1070 * This function will %resize the %forward_list to the specified
1071 * number of elements. If the number is smaller than the
1072 * %forward_list's current number of elements the %forward_list
1073 * is truncated, otherwise the %forward_list is extended and new
1074 * elements are populated with given data.
1075 */
1076 void
1077 resize(size_type __sz, const value_type& __val);
1078
1079 /**
1080 * @brief Erases all the elements.
1081 *
1082 * Note that this function only erases
1083 * the elements, and that if the elements themselves are
1084 * pointers, the pointed-to memory is not touched in any way.
1085 * Managing the pointer is the user's responsibility.
1086 */
1087 void
1088 clear() noexcept
1089 { this->_M_erase_after(&this->_M_impl._M_head, nullptr); }
1090
1091 // 23.3.4.6 forward_list operations:
1092
1093 /**
1094 * @brief Insert contents of another %forward_list.
1095 * @param __pos Iterator referencing the element to insert after.
1096 * @param __list Source list.
1097 *
1098 * The elements of @a list are inserted in constant time after
1099 * the element referenced by @a pos. @a list becomes an empty
1100 * list.
1101 *
1102 * Requires this != @a x.
1103 */
1104 void
1105 splice_after(const_iterator __pos, forward_list&& __list) noexcept
1106 {
1107 if (!__list.empty())
1108 _M_splice_after(__pos, __list.before_begin(), __list.end());
1109 }
1110
1111 void
1112 splice_after(const_iterator __pos, forward_list& __list) noexcept
1113 { splice_after(__pos, std::move(__list)); }
1114
1115 /**
1116 * @brief Insert element from another %forward_list.
1117 * @param __pos Iterator referencing the element to insert after.
1118 * @param __list Source list.
1119 * @param __i Iterator referencing the element before the element
1120 * to move.
1121 *
1122 * Removes the element in list @a list referenced by @a i and
1123 * inserts it into the current list after @a pos.
1124 */
1125 void
1126 splice_after(const_iterator __pos, forward_list&& __list,
1127 const_iterator __i) noexcept;
1128
1129 void
1130 splice_after(const_iterator __pos, forward_list& __list,
1131 const_iterator __i) noexcept
1132 { splice_after(__pos, std::move(__list), __i); }
1133
1134 /**
1135 * @brief Insert range from another %forward_list.
1136 * @param __pos Iterator referencing the element to insert after.
1137 * @param __list Source list.
1138 * @param __before Iterator referencing before the start of range
1139 * in list.
1140 * @param __last Iterator referencing the end of range in list.
1141 *
1142 * Removes elements in the range (__before,__last) and inserts them
1143 * after @a __pos in constant time.
1144 *
1145 * Undefined if @a __pos is in (__before,__last).
1146 * @{
1147 */
1148 void
1149 splice_after(const_iterator __pos, forward_list&&,
1150 const_iterator __before, const_iterator __last) noexcept
1151 { _M_splice_after(__pos, __before, __last); }
1152
1153 void
1154 splice_after(const_iterator __pos, forward_list&,
1155 const_iterator __before, const_iterator __last) noexcept
1156 { _M_splice_after(__pos, __before, __last); }
1157 // @}
1158
1159 /**
1160 * @brief Remove all elements equal to value.
1161 * @param __val The value to remove.
1162 *
1163 * Removes every element in the list equal to @a __val.
1164 * Remaining elements stay in list order. Note that this
1165 * function only erases the elements, and that if the elements
1166 * themselves are pointers, the pointed-to memory is not
1167 * touched in any way. Managing the pointer is the user's
1168 * responsibility.
1169 */
1170 void
1171 remove(const _Tp& __val);
1172
1173 /**
1174 * @brief Remove all elements satisfying a predicate.
1175 * @param __pred Unary predicate function or object.
1176 *
1177 * Removes every element in the list for which the predicate
1178 * returns true. Remaining elements stay in list order. Note
1179 * that this function only erases the elements, and that if the
1180 * elements themselves are pointers, the pointed-to memory is
1181 * not touched in any way. Managing the pointer is the user's
1182 * responsibility.
1183 */
1184 template<typename _Pred>
1185 void
1186 remove_if(_Pred __pred);
1187
1188 /**
1189 * @brief Remove consecutive duplicate elements.
1190 *
1191 * For each consecutive set of elements with the same value,
1192 * remove all but the first one. Remaining elements stay in
1193 * list order. Note that this function only erases the
1194 * elements, and that if the elements themselves are pointers,
1195 * the pointed-to memory is not touched in any way. Managing
1196 * the pointer is the user's responsibility.
1197 */
1198 void
1199 unique()
1200 { unique(std::equal_to<_Tp>()); }
1201
1202 /**
1203 * @brief Remove consecutive elements satisfying a predicate.
1204 * @param __binary_pred Binary predicate function or object.
1205 *
1206 * For each consecutive set of elements [first,last) that
1207 * satisfy predicate(first,i) where i is an iterator in
1208 * [first,last), remove all but the first one. Remaining
1209 * elements stay in list order. Note that this function only
1210 * erases the elements, and that if the elements themselves are
1211 * pointers, the pointed-to memory is not touched in any way.
1212 * Managing the pointer is the user's responsibility.
1213 */
1214 template<typename _BinPred>
1215 void
1216 unique(_BinPred __binary_pred);
1217
1218 /**
1219 * @brief Merge sorted lists.
1220 * @param __list Sorted list to merge.
1221 *
1222 * Assumes that both @a list and this list are sorted according to
1223 * operator<(). Merges elements of @a __list into this list in
1224 * sorted order, leaving @a __list empty when complete. Elements in
1225 * this list precede elements in @a __list that are equal.
1226 */
1227 void
1228 merge(forward_list&& __list)
1229 { merge(std::move(__list), std::less<_Tp>()); }
1230
1231 void
1232 merge(forward_list& __list)
1233 { merge(std::move(__list)); }
1234
1235 /**
1236 * @brief Merge sorted lists according to comparison function.
1237 * @param __list Sorted list to merge.
1238 * @param __comp Comparison function defining sort order.
1239 *
1240 * Assumes that both @a __list and this list are sorted according to
1241 * comp. Merges elements of @a __list into this list
1242 * in sorted order, leaving @a __list empty when complete. Elements
1243 * in this list precede elements in @a __list that are equivalent
1244 * according to comp().
1245 */
1246 template<typename _Comp>
1247 void
1248 merge(forward_list&& __list, _Comp __comp);
1249
1250 template<typename _Comp>
1251 void
1252 merge(forward_list& __list, _Comp __comp)
1253 { merge(std::move(__list), __comp); }
1254
1255 /**
1256 * @brief Sort the elements of the list.
1257 *
1258 * Sorts the elements of this list in NlogN time. Equivalent
1259 * elements remain in list order.
1260 */
1261 void
1262 sort()
1263 { sort(std::less<_Tp>()); }
1264
1265 /**
1266 * @brief Sort the forward_list using a comparison function.
1267 *
1268 * Sorts the elements of this list in NlogN time. Equivalent
1269 * elements remain in list order.
1270 */
1271 template<typename _Comp>
1272 void
1273 sort(_Comp __comp);
1274
1275 /**
1276 * @brief Reverse the elements in list.
1277 *
1278 * Reverse the order of elements in the list in linear time.
1279 */
1280 void
1281 reverse() noexcept
1282 { this->_M_impl._M_head._M_reverse_after(); }
1283
1284 private:
1285 // Called by the range constructor to implement [23.3.4.2]/9
1286 template<typename _InputIterator>
1287 void
1288 _M_range_initialize(_InputIterator __first, _InputIterator __last);
1289
1290 // Called by forward_list(n,v,a), and the range constructor when it
1291 // turns out to be the same thing.
1292 void
1293 _M_fill_initialize(size_type __n, const value_type& __value);
1294
1295 // Called by splice_after and insert_after.
1296 iterator
1297 _M_splice_after(const_iterator __pos, const_iterator __before,
1298 const_iterator __last);
1299
1300 // Called by forward_list(n).
1301 void
1302 _M_default_initialize(size_type __n);
1303
1304 // Called by resize(sz).
1305 void
1306 _M_default_insert_after(const_iterator __pos, size_type __n);
1307
1308 // Called by operator=(forward_list&&)
1309 void
1310 _M_move_assign(forward_list&& __list, true_type) noexcept
1311 {
1312 clear();
1313 this->_M_impl._M_head._M_next = __list._M_impl._M_head._M_next;
1314 __list._M_impl._M_head._M_next = nullptr;
1315 std::__alloc_on_move(this->_M_get_Node_allocator(),
1316 __list._M_get_Node_allocator());
1317 }
1318
1319 // Called by operator=(forward_list&&)
1320 void
1321 _M_move_assign(forward_list&& __list, false_type)
1322 {
1323 if (__list._M_get_Node_allocator() == this->_M_get_Node_allocator())
1324 _M_move_assign(std::move(__list), true_type());
1325 else
1326 // The rvalue's allocator cannot be moved, or is not equal,
1327 // so we need to individually move each element.
1328 this->assign(std::__make_move_if_noexcept_iterator(__list.begin()),
1329 std::__make_move_if_noexcept_iterator(__list.end()));
1330 }
1331
1332 // Called by assign(_InputIterator, _InputIterator) if _Tp is
1333 // CopyAssignable.
1334 template<typename _InputIterator>
1335 void
1336 _M_assign(_InputIterator __first, _InputIterator __last, true_type)
1337 {
1338 auto __prev = before_begin();
1339 auto __curr = begin();
1340 auto __end = end();
1341 while (__curr != __end && __first != __last)
1342 {
1343 *__curr = *__first;
1344 ++__prev;
1345 ++__curr;
1346 ++__first;
1347 }
1348 if (__first != __last)
1349 insert_after(__prev, __first, __last);
1350 else if (__curr != __end)
1351 erase_after(__prev, __end);
1352 }
1353
1354 // Called by assign(_InputIterator, _InputIterator) if _Tp is not
1355 // CopyAssignable.
1356 template<typename _InputIterator>
1357 void
1358 _M_assign(_InputIterator __first, _InputIterator __last, false_type)
1359 {
1360 clear();
1361 insert_after(cbefore_begin(), __first, __last);
1362 }
1363
1364 // Called by assign(size_type, const _Tp&) if Tp is CopyAssignable
1365 void
1366 _M_assign_n(size_type __n, const _Tp& __val, true_type)
1367 {
1368 auto __prev = before_begin();
1369 auto __curr = begin();
1370 auto __end = end();
1371 while (__curr != __end && __n > 0)
1372 {
1373 *__curr = __val;
1374 ++__prev;
1375 ++__curr;
1376 --__n;
1377 }
1378 if (__n > 0)
1379 insert_after(__prev, __n, __val);
1380 else if (__curr != __end)
1381 erase_after(__prev, __end);
1382 }
1383
1384 // Called by assign(size_type, const _Tp&) if Tp is non-CopyAssignable
1385 void
1386 _M_assign_n(size_type __n, const _Tp& __val, false_type)
1387 {
1388 clear();
1389 insert_after(cbefore_begin(), __n, __val);
1390 }
1391 };
1392
1393#if __cpp_deduction_guides >= 201606
1394 template<typename _InputIterator, typename _ValT
1395 = typename iterator_traits<_InputIterator>::value_type,
1396 typename _Allocator = allocator<_ValT>,
1397 typename = _RequireInputIter<_InputIterator>,
1398 typename = _RequireAllocator<_Allocator>>
1399 forward_list(_InputIterator, _InputIterator, _Allocator = _Allocator())
1400 -> forward_list<_ValT, _Allocator>;
1401#endif
1402
1403 /**
1404 * @brief Forward list equality comparison.
1405 * @param __lx A %forward_list
1406 * @param __ly A %forward_list of the same type as @a __lx.
1407 * @return True iff the elements of the forward lists are equal.
1408 *
1409 * This is an equivalence relation. It is linear in the number of
1410 * elements of the forward lists. Deques are considered equivalent
1411 * if corresponding elements compare equal.
1412 */
1413 template<typename _Tp, typename _Alloc>
1414 bool
1415 operator==(const forward_list<_Tp, _Alloc>& __lx,
1416 const forward_list<_Tp, _Alloc>& __ly);
1417
1418 /**
1419 * @brief Forward list ordering relation.
1420 * @param __lx A %forward_list.
1421 * @param __ly A %forward_list of the same type as @a __lx.
1422 * @return True iff @a __lx is lexicographically less than @a __ly.
1423 *
1424 * This is a total ordering relation. It is linear in the number of
1425 * elements of the forward lists. The elements must be comparable
1426 * with @c <.
1427 *
1428 * See std::lexicographical_compare() for how the determination is made.
1429 */
1430 template<typename _Tp, typename _Alloc>
1431 inline bool
1432 operator<(const forward_list<_Tp, _Alloc>& __lx,
1433 const forward_list<_Tp, _Alloc>& __ly)
1434 { return std::lexicographical_compare(__lx.cbegin(), __lx.cend(),
1435 __ly.cbegin(), __ly.cend()); }
1436
1437 /// Based on operator==
1438 template<typename _Tp, typename _Alloc>
1439 inline bool
1440 operator!=(const forward_list<_Tp, _Alloc>& __lx,
1441 const forward_list<_Tp, _Alloc>& __ly)
1442 { return !(__lx == __ly); }
1443
1444 /// Based on operator<
1445 template<typename _Tp, typename _Alloc>
1446 inline bool
1447 operator>(const forward_list<_Tp, _Alloc>& __lx,
1448 const forward_list<_Tp, _Alloc>& __ly)
1449 { return (__ly < __lx); }
1450
1451 /// Based on operator<
1452 template<typename _Tp, typename _Alloc>
1453 inline bool
1454 operator>=(const forward_list<_Tp, _Alloc>& __lx,
1455 const forward_list<_Tp, _Alloc>& __ly)
1456 { return !(__lx < __ly); }
1457
1458 /// Based on operator<
1459 template<typename _Tp, typename _Alloc>
1460 inline bool
1461 operator<=(const forward_list<_Tp, _Alloc>& __lx,
1462 const forward_list<_Tp, _Alloc>& __ly)
1463 { return !(__ly < __lx); }
1464
1465 /// See std::forward_list::swap().
1466 template<typename _Tp, typename _Alloc>
1467 inline void
1468 swap(forward_list<_Tp, _Alloc>& __lx,
1469 forward_list<_Tp, _Alloc>& __ly)
1470 noexcept(noexcept(__lx.swap(__ly)))
1471 { __lx.swap(__ly); }
1472
1473_GLIBCXX_END_NAMESPACE_CONTAINER
1474_GLIBCXX_END_NAMESPACE_VERSION
1475} // namespace std
1476
1477#endif // _FORWARD_LIST_H
1478