1 // Deque implementation -*- C++ -*-
2
3 // Copyright (C) 2001-2023 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 /*
26 *
27 * Copyright (c) 1994
28 * Hewlett-Packard Company
29 *
30 * Permission to use, copy, modify, distribute and sell this software
31 * and its documentation for any purpose is hereby granted without fee,
32 * provided that the above copyright notice appear in all copies and
33 * that both that copyright notice and this permission notice appear
34 * in supporting documentation. Hewlett-Packard Company makes no
35 * representations about the suitability of this software for any
36 * purpose. It is provided "as is" without express or implied warranty.
37 *
38 *
39 * Copyright (c) 1997
40 * Silicon Graphics Computer Systems, Inc.
41 *
42 * Permission to use, copy, modify, distribute and sell this software
43 * and its documentation for any purpose is hereby granted without fee,
44 * provided that the above copyright notice appear in all copies and
45 * that both that copyright notice and this permission notice appear
46 * in supporting documentation. Silicon Graphics makes no
47 * representations about the suitability of this software for any
48 * purpose. It is provided "as is" without express or implied warranty.
49 */
50
51 /** @file bits/stl_deque.h
52 * This is an internal header file, included by other library headers.
53 * Do not attempt to use it directly. @headername{deque}
54 */
55
56 #ifndef _STL_DEQUE_H
57 #define _STL_DEQUE_H 1
58
59 #include <bits/concept_check.h>
60 #include <bits/stl_iterator_base_types.h>
61 #include <bits/stl_iterator_base_funcs.h>
62 #if __cplusplus >= 201103L
63 #include <initializer_list>
64 #include <bits/stl_uninitialized.h> // for __is_bitwise_relocatable
65 #endif
66 #if __cplusplus > 201703L
67 # include <compare>
68 #endif
69
70 #include <debug/assertions.h>
71
72 namespace std _GLIBCXX_VISIBILITY(default)
73 {
74 _GLIBCXX_BEGIN_NAMESPACE_VERSION
75 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
76
77 /**
78 * @brief This function controls the size of memory nodes.
79 * @param __size The size of an element.
80 * @return The number (not byte size) of elements per node.
81 *
82 * This function started off as a compiler kludge from SGI, but
83 * seems to be a useful wrapper around a repeated constant
84 * expression. The @b 512 is tunable (and no other code needs to
85 * change), but no investigation has been done since inheriting the
86 * SGI code. Touch _GLIBCXX_DEQUE_BUF_SIZE only if you know what
87 * you are doing, however: changing it breaks the binary
88 * compatibility!!
89 */
90
91 #ifndef _GLIBCXX_DEQUE_BUF_SIZE
92 #define _GLIBCXX_DEQUE_BUF_SIZE 512
93 #endif
94
95 _GLIBCXX_CONSTEXPR inline size_t
96 __deque_buf_size(size_t __size)
97 { return (__size < _GLIBCXX_DEQUE_BUF_SIZE
98 ? size_t(_GLIBCXX_DEQUE_BUF_SIZE / __size) : size_t(1)); }
99
100
101 /**
102 * @brief A deque::iterator.
103 *
104 * Quite a bit of intelligence here. Much of the functionality of
105 * deque is actually passed off to this class. A deque holds two
106 * of these internally, marking its valid range. Access to
107 * elements is done as offsets of either of those two, relying on
108 * operator overloading in this class.
109 *
110 * All the functions are op overloads except for _M_set_node.
111 */
112 template<typename _Tp, typename _Ref, typename _Ptr>
113 struct _Deque_iterator
114 {
115 #if __cplusplus < 201103L
116 typedef _Deque_iterator<_Tp, _Tp&, _Tp*> iterator;
117 typedef _Deque_iterator<_Tp, const _Tp&, const _Tp*> const_iterator;
118 typedef _Tp* _Elt_pointer;
119 typedef _Tp** _Map_pointer;
120 #else
121 private:
122 template<typename _CvTp>
123 using __iter = _Deque_iterator<_Tp, _CvTp&, __ptr_rebind<_Ptr, _CvTp>>;
124 public:
125 typedef __iter<_Tp> iterator;
126 typedef __iter<const _Tp> const_iterator;
127 typedef __ptr_rebind<_Ptr, _Tp> _Elt_pointer;
128 typedef __ptr_rebind<_Ptr, _Elt_pointer> _Map_pointer;
129 #endif
130
131 static size_t _S_buffer_size() _GLIBCXX_NOEXCEPT
132 { return __deque_buf_size(sizeof(_Tp)); }
133
134 typedef std::random_access_iterator_tag iterator_category;
135 typedef _Tp value_type;
136 typedef _Ptr pointer;
137 typedef _Ref reference;
138 typedef size_t size_type;
139 typedef ptrdiff_t difference_type;
140 typedef _Deque_iterator _Self;
141
142 _Elt_pointer _M_cur;
143 _Elt_pointer _M_first;
144 _Elt_pointer _M_last;
145 _Map_pointer _M_node;
146
147 _Deque_iterator(_Elt_pointer __x, _Map_pointer __y) _GLIBCXX_NOEXCEPT
148 : _M_cur(__x), _M_first(*__y),
149 _M_last(*__y + _S_buffer_size()), _M_node(__y) { }
150
151 _Deque_iterator() _GLIBCXX_NOEXCEPT
152 : _M_cur(), _M_first(), _M_last(), _M_node() { }
153
154 #if __cplusplus < 201103L
155 // Conversion from iterator to const_iterator.
156 _Deque_iterator(const iterator& __x) _GLIBCXX_NOEXCEPT
157 : _M_cur(__x._M_cur), _M_first(__x._M_first),
158 _M_last(__x._M_last), _M_node(__x._M_node) { }
159 #else
160 // Conversion from iterator to const_iterator.
161 template<typename _Iter,
162 typename = _Require<is_same<_Self, const_iterator>,
163 is_same<_Iter, iterator>>>
164 _Deque_iterator(const _Iter& __x) noexcept
165 : _M_cur(__x._M_cur), _M_first(__x._M_first),
166 _M_last(__x._M_last), _M_node(__x._M_node) { }
167
168 _Deque_iterator(const _Deque_iterator& __x) noexcept
169 : _M_cur(__x._M_cur), _M_first(__x._M_first),
170 _M_last(__x._M_last), _M_node(__x._M_node) { }
171
172 _Deque_iterator& operator=(const _Deque_iterator&) = default;
173 #endif
174
175 iterator
176 _M_const_cast() const _GLIBCXX_NOEXCEPT
177 { return iterator(_M_cur, _M_node); }
178
179 _GLIBCXX_NODISCARD
180 reference
181 operator*() const _GLIBCXX_NOEXCEPT
182 { return *_M_cur; }
183
184 _GLIBCXX_NODISCARD
185 pointer
186 operator->() const _GLIBCXX_NOEXCEPT
187 { return _M_cur; }
188
189 _Self&
190 operator++() _GLIBCXX_NOEXCEPT
191 {
192 ++_M_cur;
193 if (_M_cur == _M_last)
194 {
195 _M_set_node(_M_node + 1);
196 _M_cur = _M_first;
197 }
198 return *this;
199 }
200
201 _Self
202 operator++(int) _GLIBCXX_NOEXCEPT
203 {
204 _Self __tmp = *this;
205 ++*this;
206 return __tmp;
207 }
208
209 _Self&
210 operator--() _GLIBCXX_NOEXCEPT
211 {
212 if (_M_cur == _M_first)
213 {
214 _M_set_node(_M_node - 1);
215 _M_cur = _M_last;
216 }
217 --_M_cur;
218 return *this;
219 }
220
221 _Self
222 operator--(int) _GLIBCXX_NOEXCEPT
223 {
224 _Self __tmp = *this;
225 --*this;
226 return __tmp;
227 }
228
229 _Self&
230 operator+=(difference_type __n) _GLIBCXX_NOEXCEPT
231 {
232 const difference_type __offset = __n + (_M_cur - _M_first);
233 if (__offset >= 0 && __offset < difference_type(_S_buffer_size()))
234 _M_cur += __n;
235 else
236 {
237 const difference_type __node_offset =
238 __offset > 0 ? __offset / difference_type(_S_buffer_size())
239 : -difference_type((-__offset - 1)
240 / _S_buffer_size()) - 1;
241 _M_set_node(_M_node + __node_offset);
242 _M_cur = _M_first + (__offset - __node_offset
243 * difference_type(_S_buffer_size()));
244 }
245 return *this;
246 }
247
248 _Self&
249 operator-=(difference_type __n) _GLIBCXX_NOEXCEPT
250 { return *this += -__n; }
251
252 _GLIBCXX_NODISCARD
253 reference
254 operator[](difference_type __n) const _GLIBCXX_NOEXCEPT
255 { return *(*this + __n); }
256
257 /**
258 * Prepares to traverse new_node. Sets everything except
259 * _M_cur, which should therefore be set by the caller
260 * immediately afterwards, based on _M_first and _M_last.
261 */
262 void
263 _M_set_node(_Map_pointer __new_node) _GLIBCXX_NOEXCEPT
264 {
265 _M_node = __new_node;
266 _M_first = *__new_node;
267 _M_last = _M_first + difference_type(_S_buffer_size());
268 }
269
270 _GLIBCXX_NODISCARD
271 friend bool
272 operator==(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
273 { return __x._M_cur == __y._M_cur; }
274
275 // Note: we also provide overloads whose operands are of the same type in
276 // order to avoid ambiguous overload resolution when std::rel_ops
277 // operators are in scope (for additional details, see libstdc++/3628)
278 template<typename _RefR, typename _PtrR>
279 _GLIBCXX_NODISCARD
280 friend bool
281 operator==(const _Self& __x,
282 const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
283 _GLIBCXX_NOEXCEPT
284 { return __x._M_cur == __y._M_cur; }
285
286 #if __cpp_lib_three_way_comparison
287 [[nodiscard]]
288 friend strong_ordering
289 operator<=>(const _Self& __x, const _Self& __y) noexcept
290 {
291 if (const auto __cmp = __x._M_node <=> __y._M_node; __cmp != 0)
292 return __cmp;
293 return __x._M_cur <=> __y._M_cur;
294 }
295 #else
296 _GLIBCXX_NODISCARD
297 friend bool
298 operator!=(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
299 { return !(__x == __y); }
300
301 template<typename _RefR, typename _PtrR>
302 _GLIBCXX_NODISCARD
303 friend bool
304 operator!=(const _Self& __x,
305 const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
306 _GLIBCXX_NOEXCEPT
307 { return !(__x == __y); }
308
309 _GLIBCXX_NODISCARD
310 friend bool
311 operator<(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
312 {
313 return (__x._M_node == __y._M_node)
314 ? (__x._M_cur < __y._M_cur) : (__x._M_node < __y._M_node);
315 }
316
317 template<typename _RefR, typename _PtrR>
318 _GLIBCXX_NODISCARD
319 friend bool
320 operator<(const _Self& __x,
321 const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
322 _GLIBCXX_NOEXCEPT
323 {
324 return (__x._M_node == __y._M_node)
325 ? (__x._M_cur < __y._M_cur) : (__x._M_node < __y._M_node);
326 }
327
328 _GLIBCXX_NODISCARD
329 friend bool
330 operator>(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
331 { return __y < __x; }
332
333 template<typename _RefR, typename _PtrR>
334 _GLIBCXX_NODISCARD
335 friend bool
336 operator>(const _Self& __x,
337 const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
338 _GLIBCXX_NOEXCEPT
339 { return __y < __x; }
340
341 _GLIBCXX_NODISCARD
342 friend bool
343 operator<=(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
344 { return !(__y < __x); }
345
346 template<typename _RefR, typename _PtrR>
347 _GLIBCXX_NODISCARD
348 friend bool
349 operator<=(const _Self& __x,
350 const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
351 _GLIBCXX_NOEXCEPT
352 { return !(__y < __x); }
353
354 _GLIBCXX_NODISCARD
355 friend bool
356 operator>=(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
357 { return !(__x < __y); }
358
359 template<typename _RefR, typename _PtrR>
360 _GLIBCXX_NODISCARD
361 friend bool
362 operator>=(const _Self& __x,
363 const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
364 _GLIBCXX_NOEXCEPT
365 { return !(__x < __y); }
366 #endif // three-way comparison
367
368 _GLIBCXX_NODISCARD
369 friend difference_type
370 operator-(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
371 {
372 return difference_type(_S_buffer_size())
373 * (__x._M_node - __y._M_node - bool(__x._M_node))
374 + (__x._M_cur - __x._M_first)
375 + (__y._M_last - __y._M_cur);
376 }
377
378 // _GLIBCXX_RESOLVE_LIB_DEFECTS
379 // According to the resolution of DR179 not only the various comparison
380 // operators but also operator- must accept mixed iterator/const_iterator
381 // parameters.
382 template<typename _RefR, typename _PtrR>
383 _GLIBCXX_NODISCARD
384 friend difference_type
385 operator-(const _Self& __x,
386 const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
387 _GLIBCXX_NOEXCEPT
388 {
389 return difference_type(_S_buffer_size())
390 * (__x._M_node - __y._M_node - bool(__x._M_node))
391 + (__x._M_cur - __x._M_first)
392 + (__y._M_last - __y._M_cur);
393 }
394
395 _GLIBCXX_NODISCARD
396 friend _Self
397 operator+(const _Self& __x, difference_type __n) _GLIBCXX_NOEXCEPT
398 {
399 _Self __tmp = __x;
400 __tmp += __n;
401 return __tmp;
402 }
403
404 _GLIBCXX_NODISCARD
405 friend _Self
406 operator-(const _Self& __x, difference_type __n) _GLIBCXX_NOEXCEPT
407 {
408 _Self __tmp = __x;
409 __tmp -= __n;
410 return __tmp;
411 }
412
413 _GLIBCXX_NODISCARD
414 friend _Self
415 operator+(difference_type __n, const _Self& __x) _GLIBCXX_NOEXCEPT
416 { return __x + __n; }
417 };
418
419 /**
420 * Deque base class. This class provides the unified face for %deque's
421 * allocation. This class's constructor and destructor allocate and
422 * deallocate (but do not initialize) storage. This makes %exception
423 * safety easier.
424 *
425 * Nothing in this class ever constructs or destroys an actual Tp element.
426 * (Deque handles that itself.) Only/All memory management is performed
427 * here.
428 */
429 template<typename _Tp, typename _Alloc>
430 class _Deque_base
431 {
432 protected:
433 typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
434 rebind<_Tp>::other _Tp_alloc_type;
435 typedef __gnu_cxx::__alloc_traits<_Tp_alloc_type> _Alloc_traits;
436
437 #if __cplusplus < 201103L
438 typedef _Tp* _Ptr;
439 typedef const _Tp* _Ptr_const;
440 #else
441 typedef typename _Alloc_traits::pointer _Ptr;
442 typedef typename _Alloc_traits::const_pointer _Ptr_const;
443 #endif
444
445 typedef typename _Alloc_traits::template rebind<_Ptr>::other
446 _Map_alloc_type;
447 typedef __gnu_cxx::__alloc_traits<_Map_alloc_type> _Map_alloc_traits;
448
449 typedef _Alloc allocator_type;
450
451 allocator_type
452 get_allocator() const _GLIBCXX_NOEXCEPT
453 { return allocator_type(_M_get_Tp_allocator()); }
454
455 typedef _Deque_iterator<_Tp, _Tp&, _Ptr> iterator;
456 typedef _Deque_iterator<_Tp, const _Tp&, _Ptr_const> const_iterator;
457
458 _Deque_base()
459 : _M_impl()
460 { _M_initialize_map(0); }
461
462 _Deque_base(size_t __num_elements)
463 : _M_impl()
464 { _M_initialize_map(__num_elements); }
465
466 _Deque_base(const allocator_type& __a, size_t __num_elements)
467 : _M_impl(__a)
468 { _M_initialize_map(__num_elements); }
469
470 _Deque_base(const allocator_type& __a)
471 : _M_impl(__a)
472 { /* Caller must initialize map. */ }
473
474 #if __cplusplus >= 201103L
475 _Deque_base(_Deque_base&& __x)
476 : _M_impl(std::move(__x._M_get_Tp_allocator()))
477 {
478 _M_initialize_map(0);
479 if (__x._M_impl._M_map)
480 this->_M_impl._M_swap_data(__x._M_impl);
481 }
482
483 _Deque_base(_Deque_base&& __x, const allocator_type& __a)
484 : _M_impl(std::move(__x._M_impl), _Tp_alloc_type(__a))
485 { __x._M_initialize_map(0); }
486
487 _Deque_base(_Deque_base&& __x, const allocator_type& __a, size_t __n)
488 : _M_impl(__a)
489 {
490 if (__x.get_allocator() == __a)
491 {
492 if (__x._M_impl._M_map)
493 {
494 _M_initialize_map(0);
495 this->_M_impl._M_swap_data(__x._M_impl);
496 }
497 }
498 else
499 {
500 _M_initialize_map(__n);
501 }
502 }
503 #endif
504
505 ~_Deque_base() _GLIBCXX_NOEXCEPT;
506
507 typedef typename iterator::_Map_pointer _Map_pointer;
508
509 struct _Deque_impl_data
510 {
511 _Map_pointer _M_map;
512 size_t _M_map_size;
513 iterator _M_start;
514 iterator _M_finish;
515
516 _Deque_impl_data() _GLIBCXX_NOEXCEPT
517 : _M_map(), _M_map_size(), _M_start(), _M_finish()
518 { }
519
520 #if __cplusplus >= 201103L
521 _Deque_impl_data(const _Deque_impl_data&) = default;
522 _Deque_impl_data&
523 operator=(const _Deque_impl_data&) = default;
524
525 _Deque_impl_data(_Deque_impl_data&& __x) noexcept
526 : _Deque_impl_data(__x)
527 { __x = _Deque_impl_data(); }
528 #endif
529
530 void
531 _M_swap_data(_Deque_impl_data& __x) _GLIBCXX_NOEXCEPT
532 {
533 // Do not use std::swap(_M_start, __x._M_start), etc as it loses
534 // information used by TBAA.
535 std::swap(*this, __x);
536 }
537 };
538
539 // This struct encapsulates the implementation of the std::deque
540 // standard container and at the same time makes use of the EBO
541 // for empty allocators.
542 struct _Deque_impl
543 : public _Tp_alloc_type, public _Deque_impl_data
544 {
545 _Deque_impl() _GLIBCXX_NOEXCEPT_IF(
546 is_nothrow_default_constructible<_Tp_alloc_type>::value)
547 : _Tp_alloc_type()
548 { }
549
550 _Deque_impl(const _Tp_alloc_type& __a) _GLIBCXX_NOEXCEPT
551 : _Tp_alloc_type(__a)
552 { }
553
554 #if __cplusplus >= 201103L
555 _Deque_impl(_Deque_impl&&) = default;
556
557 _Deque_impl(_Tp_alloc_type&& __a) noexcept
558 : _Tp_alloc_type(std::move(__a))
559 { }
560
561 _Deque_impl(_Deque_impl&& __d, _Tp_alloc_type&& __a)
562 : _Tp_alloc_type(std::move(__a)), _Deque_impl_data(std::move(__d))
563 { }
564 #endif
565 };
566
567 _Tp_alloc_type&
568 _M_get_Tp_allocator() _GLIBCXX_NOEXCEPT
569 { return this->_M_impl; }
570
571 const _Tp_alloc_type&
572 _M_get_Tp_allocator() const _GLIBCXX_NOEXCEPT
573 { return this->_M_impl; }
574
575 _Map_alloc_type
576 _M_get_map_allocator() const _GLIBCXX_NOEXCEPT
577 { return _Map_alloc_type(_M_get_Tp_allocator()); }
578
579 _Ptr
580 _M_allocate_node()
581 {
582 typedef __gnu_cxx::__alloc_traits<_Tp_alloc_type> _Traits;
583 return _Traits::allocate(_M_impl, __deque_buf_size(sizeof(_Tp)));
584 }
585
586 void
587 _M_deallocate_node(_Ptr __p) _GLIBCXX_NOEXCEPT
588 {
589 typedef __gnu_cxx::__alloc_traits<_Tp_alloc_type> _Traits;
590 _Traits::deallocate(_M_impl, __p, __deque_buf_size(sizeof(_Tp)));
591 }
592
593 _Map_pointer
594 _M_allocate_map(size_t __n)
595 {
596 _Map_alloc_type __map_alloc = _M_get_map_allocator();
597 return _Map_alloc_traits::allocate(__map_alloc, __n);
598 }
599
600 void
601 _M_deallocate_map(_Map_pointer __p, size_t __n) _GLIBCXX_NOEXCEPT
602 {
603 _Map_alloc_type __map_alloc = _M_get_map_allocator();
604 _Map_alloc_traits::deallocate(__map_alloc, __p, __n);
605 }
606
607 void _M_initialize_map(size_t);
608 void _M_create_nodes(_Map_pointer __nstart, _Map_pointer __nfinish);
609 void _M_destroy_nodes(_Map_pointer __nstart,
610 _Map_pointer __nfinish) _GLIBCXX_NOEXCEPT;
611 enum { _S_initial_map_size = 8 };
612
613 _Deque_impl _M_impl;
614 };
615
616 template<typename _Tp, typename _Alloc>
617 _Deque_base<_Tp, _Alloc>::
618 ~_Deque_base() _GLIBCXX_NOEXCEPT
619 {
620 if (this->_M_impl._M_map)
621 {
622 _M_destroy_nodes(this->_M_impl._M_start._M_node,
623 this->_M_impl._M_finish._M_node + 1);
624 _M_deallocate_map(this->_M_impl._M_map, this->_M_impl._M_map_size);
625 }
626 }
627
628 /**
629 * @brief Layout storage.
630 * @param __num_elements The count of T's for which to allocate space
631 * at first.
632 * @return Nothing.
633 *
634 * The initial underlying memory layout is a bit complicated...
635 */
636 template<typename _Tp, typename _Alloc>
637 void
638 _Deque_base<_Tp, _Alloc>::
639 _M_initialize_map(size_t __num_elements)
640 {
641 const size_t __num_nodes = (__num_elements / __deque_buf_size(sizeof(_Tp))
642 + 1);
643
644 this->_M_impl._M_map_size = std::max((size_t) _S_initial_map_size,
645 size_t(__num_nodes + 2));
646 this->_M_impl._M_map = _M_allocate_map(this->_M_impl._M_map_size);
647
648 // For "small" maps (needing less than _M_map_size nodes), allocation
649 // starts in the middle elements and grows outwards. So nstart may be
650 // the beginning of _M_map, but for small maps it may be as far in as
651 // _M_map+3.
652
653 _Map_pointer __nstart = (this->_M_impl._M_map
654 + (this->_M_impl._M_map_size - __num_nodes) / 2);
655 _Map_pointer __nfinish = __nstart + __num_nodes;
656
657 __try
658 { _M_create_nodes(__nstart, __nfinish); }
659 __catch(...)
660 {
661 _M_deallocate_map(this->_M_impl._M_map, this->_M_impl._M_map_size);
662 this->_M_impl._M_map = _Map_pointer();
663 this->_M_impl._M_map_size = 0;
664 __throw_exception_again;
665 }
666
667 this->_M_impl._M_start._M_set_node(__nstart);
668 this->_M_impl._M_finish._M_set_node(__nfinish - 1);
669 this->_M_impl._M_start._M_cur = _M_impl._M_start._M_first;
670 this->_M_impl._M_finish._M_cur = (this->_M_impl._M_finish._M_first
671 + __num_elements
672 % __deque_buf_size(sizeof(_Tp)));
673 }
674
675 template<typename _Tp, typename _Alloc>
676 void
677 _Deque_base<_Tp, _Alloc>::
678 _M_create_nodes(_Map_pointer __nstart, _Map_pointer __nfinish)
679 {
680 _Map_pointer __cur;
681 __try
682 {
683 for (__cur = __nstart; __cur < __nfinish; ++__cur)
684 *__cur = this->_M_allocate_node();
685 }
686 __catch(...)
687 {
688 _M_destroy_nodes(__nstart, __cur);
689 __throw_exception_again;
690 }
691 }
692
693 template<typename _Tp, typename _Alloc>
694 void
695 _Deque_base<_Tp, _Alloc>::
696 _M_destroy_nodes(_Map_pointer __nstart,
697 _Map_pointer __nfinish) _GLIBCXX_NOEXCEPT
698 {
699 for (_Map_pointer __n = __nstart; __n < __nfinish; ++__n)
700 _M_deallocate_node(*__n);
701 }
702
703 /**
704 * @brief A standard container using fixed-size memory allocation and
705 * constant-time manipulation of elements at either end.
706 *
707 * @ingroup sequences
708 *
709 * @tparam _Tp Type of element.
710 * @tparam _Alloc Allocator type, defaults to allocator<_Tp>.
711 *
712 * Meets the requirements of a <a href="tables.html#65">container</a>, a
713 * <a href="tables.html#66">reversible container</a>, and a
714 * <a href="tables.html#67">sequence</a>, including the
715 * <a href="tables.html#68">optional sequence requirements</a>.
716 *
717 * In previous HP/SGI versions of deque, there was an extra template
718 * parameter so users could control the node size. This extension turned
719 * out to violate the C++ standard (it can be detected using template
720 * template parameters), and it was removed.
721 *
722 * Here's how a deque<Tp> manages memory. Each deque has 4 members:
723 *
724 * - Tp** _M_map
725 * - size_t _M_map_size
726 * - iterator _M_start, _M_finish
727 *
728 * map_size is at least 8. %map is an array of map_size
729 * pointers-to-@a nodes. (The name %map has nothing to do with the
730 * std::map class, and @b nodes should not be confused with
731 * std::list's usage of @a node.)
732 *
733 * A @a node has no specific type name as such, but it is referred
734 * to as @a node in this file. It is a simple array-of-Tp. If Tp
735 * is very large, there will be one Tp element per node (i.e., an
736 * @a array of one). For non-huge Tp's, node size is inversely
737 * related to Tp size: the larger the Tp, the fewer Tp's will fit
738 * in a node. The goal here is to keep the total size of a node
739 * relatively small and constant over different Tp's, to improve
740 * allocator efficiency.
741 *
742 * Not every pointer in the %map array will point to a node. If
743 * the initial number of elements in the deque is small, the
744 * /middle/ %map pointers will be valid, and the ones at the edges
745 * will be unused. This same situation will arise as the %map
746 * grows: available %map pointers, if any, will be on the ends. As
747 * new nodes are created, only a subset of the %map's pointers need
748 * to be copied @a outward.
749 *
750 * Class invariants:
751 * - For any nonsingular iterator i:
752 * - i.node points to a member of the %map array. (Yes, you read that
753 * correctly: i.node does not actually point to a node.) The member of
754 * the %map array is what actually points to the node.
755 * - i.first == *(i.node) (This points to the node (first Tp element).)
756 * - i.last == i.first + node_size
757 * - i.cur is a pointer in the range [i.first, i.last). NOTE:
758 * the implication of this is that i.cur is always a dereferenceable
759 * pointer, even if i is a past-the-end iterator.
760 * - Start and Finish are always nonsingular iterators. NOTE: this
761 * means that an empty deque must have one node, a deque with <N
762 * elements (where N is the node buffer size) must have one node, a
763 * deque with N through (2N-1) elements must have two nodes, etc.
764 * - For every node other than start.node and finish.node, every
765 * element in the node is an initialized object. If start.node ==
766 * finish.node, then [start.cur, finish.cur) are initialized
767 * objects, and the elements outside that range are uninitialized
768 * storage. Otherwise, [start.cur, start.last) and [finish.first,
769 * finish.cur) are initialized objects, and [start.first, start.cur)
770 * and [finish.cur, finish.last) are uninitialized storage.
771 * - [%map, %map + map_size) is a valid, non-empty range.
772 * - [start.node, finish.node] is a valid range contained within
773 * [%map, %map + map_size).
774 * - A pointer in the range [%map, %map + map_size) points to an allocated
775 * node if and only if the pointer is in the range
776 * [start.node, finish.node].
777 *
778 * Here's the magic: nothing in deque is @b aware of the discontiguous
779 * storage!
780 *
781 * The memory setup and layout occurs in the parent, _Base, and the iterator
782 * class is entirely responsible for @a leaping from one node to the next.
783 * All the implementation routines for deque itself work only through the
784 * start and finish iterators. This keeps the routines simple and sane,
785 * and we can use other standard algorithms as well.
786 */
787 template<typename _Tp, typename _Alloc = std::allocator<_Tp> >
788 class deque : protected _Deque_base<_Tp, _Alloc>
789 {
790 #ifdef _GLIBCXX_CONCEPT_CHECKS
791 // concept requirements
792 typedef typename _Alloc::value_type _Alloc_value_type;
793 # if __cplusplus < 201103L
794 __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
795 # endif
796 __glibcxx_class_requires2(_Tp, _Alloc_value_type, _SameTypeConcept)
797 #endif
798
799 #if __cplusplus >= 201103L
800 static_assert(is_same<typename remove_cv<_Tp>::type, _Tp>::value,
801 "std::deque must have a non-const, non-volatile value_type");
802 # if __cplusplus > 201703L || defined __STRICT_ANSI__
803 static_assert(is_same<typename _Alloc::value_type, _Tp>::value,
804 "std::deque must have the same value_type as its allocator");
805 # endif
806 #endif
807
808 typedef _Deque_base<_Tp, _Alloc> _Base;
809 typedef typename _Base::_Tp_alloc_type _Tp_alloc_type;
810 typedef typename _Base::_Alloc_traits _Alloc_traits;
811 typedef typename _Base::_Map_pointer _Map_pointer;
812
813 public:
814 typedef _Tp value_type;
815 typedef typename _Alloc_traits::pointer pointer;
816 typedef typename _Alloc_traits::const_pointer const_pointer;
817 typedef typename _Alloc_traits::reference reference;
818 typedef typename _Alloc_traits::const_reference const_reference;
819 typedef typename _Base::iterator iterator;
820 typedef typename _Base::const_iterator const_iterator;
821 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
822 typedef std::reverse_iterator<iterator> reverse_iterator;
823 typedef size_t size_type;
824 typedef ptrdiff_t difference_type;
825 typedef _Alloc allocator_type;
826
827 private:
828 static size_t _S_buffer_size() _GLIBCXX_NOEXCEPT
829 { return __deque_buf_size(sizeof(_Tp)); }
830
831 // Functions controlling memory layout, and nothing else.
832 using _Base::_M_initialize_map;
833 using _Base::_M_create_nodes;
834 using _Base::_M_destroy_nodes;
835 using _Base::_M_allocate_node;
836 using _Base::_M_deallocate_node;
837 using _Base::_M_allocate_map;
838 using _Base::_M_deallocate_map;
839 using _Base::_M_get_Tp_allocator;
840
841 /**
842 * A total of four data members accumulated down the hierarchy.
843 * May be accessed via _M_impl.*
844 */
845 using _Base::_M_impl;
846
847 public:
848 // [23.2.1.1] construct/copy/destroy
849 // (assign() and get_allocator() are also listed in this section)
850
851 /**
852 * @brief Creates a %deque with no elements.
853 */
854 #if __cplusplus >= 201103L
855 deque() = default;
856 #else
857 deque() { }
858 #endif
859
860 /**
861 * @brief Creates a %deque with no elements.
862 * @param __a An allocator object.
863 */
864 explicit
865 deque(const allocator_type& __a)
866 : _Base(__a, 0) { }
867
868 #if __cplusplus >= 201103L
869 /**
870 * @brief Creates a %deque with default constructed elements.
871 * @param __n The number of elements to initially create.
872 * @param __a An allocator.
873 *
874 * This constructor fills the %deque with @a n default
875 * constructed elements.
876 */
877 explicit
878 deque(size_type __n, const allocator_type& __a = allocator_type())
879 : _Base(__a, _S_check_init_len(__n, __a))
880 { _M_default_initialize(); }
881
882 /**
883 * @brief Creates a %deque with copies of an exemplar element.
884 * @param __n The number of elements to initially create.
885 * @param __value An element to copy.
886 * @param __a An allocator.
887 *
888 * This constructor fills the %deque with @a __n copies of @a __value.
889 */
890 deque(size_type __n, const value_type& __value,
891 const allocator_type& __a = allocator_type())
892 : _Base(__a, _S_check_init_len(__n, __a))
893 { _M_fill_initialize(__value); }
894 #else
895 /**
896 * @brief Creates a %deque with copies of an exemplar element.
897 * @param __n The number of elements to initially create.
898 * @param __value An element to copy.
899 * @param __a An allocator.
900 *
901 * This constructor fills the %deque with @a __n copies of @a __value.
902 */
903 explicit
904 deque(size_type __n, const value_type& __value = value_type(),
905 const allocator_type& __a = allocator_type())
906 : _Base(__a, _S_check_init_len(__n, __a))
907 { _M_fill_initialize(__value); }
908 #endif
909
910 /**
911 * @brief %Deque copy constructor.
912 * @param __x A %deque of identical element and allocator types.
913 *
914 * The newly-created %deque uses a copy of the allocator object used
915 * by @a __x (unless the allocator traits dictate a different object).
916 */
917 deque(const deque& __x)
918 : _Base(_Alloc_traits::_S_select_on_copy(__x._M_get_Tp_allocator()),
919 __x.size())
920 { std::__uninitialized_copy_a(__x.begin(), __x.end(),
921 this->_M_impl._M_start,
922 _M_get_Tp_allocator()); }
923
924 #if __cplusplus >= 201103L
925 /**
926 * @brief %Deque move constructor.
927 *
928 * The newly-created %deque contains the exact contents of the
929 * moved instance.
930 * The contents of the moved instance are a valid, but unspecified
931 * %deque.
932 */
933 deque(deque&&) = default;
934
935 /// Copy constructor with alternative allocator
936 deque(const deque& __x, const __type_identity_t<allocator_type>& __a)
937 : _Base(__a, __x.size())
938 { std::__uninitialized_copy_a(__x.begin(), __x.end(),
939 this->_M_impl._M_start,
940 _M_get_Tp_allocator()); }
941
942 /// Move constructor with alternative allocator
943 deque(deque&& __x, const __type_identity_t<allocator_type>& __a)
944 : deque(std::move(__x), __a, typename _Alloc_traits::is_always_equal{})
945 { }
946
947 private:
948 deque(deque&& __x, const allocator_type& __a, true_type)
949 : _Base(std::move(__x), __a)
950 { }
951
952 deque(deque&& __x, const allocator_type& __a, false_type)
953 : _Base(std::move(__x), __a, __x.size())
954 {
955 if (__x.get_allocator() != __a && !__x.empty())
956 {
957 std::__uninitialized_move_a(__x.begin(), __x.end(),
958 this->_M_impl._M_start,
959 _M_get_Tp_allocator());
960 __x.clear();
961 }
962 }
963
964 public:
965 /**
966 * @brief Builds a %deque from an initializer list.
967 * @param __l An initializer_list.
968 * @param __a An allocator object.
969 *
970 * Create a %deque consisting of copies of the elements in the
971 * initializer_list @a __l.
972 *
973 * This will call the element type's copy constructor N times
974 * (where N is __l.size()) and do no memory reallocation.
975 */
976 deque(initializer_list<value_type> __l,
977 const allocator_type& __a = allocator_type())
978 : _Base(__a)
979 {
980 _M_range_initialize(__l.begin(), __l.end(),
981 random_access_iterator_tag());
982 }
983 #endif
984
985 /**
986 * @brief Builds a %deque from a range.
987 * @param __first An input iterator.
988 * @param __last An input iterator.
989 * @param __a An allocator object.
990 *
991 * Create a %deque consisting of copies of the elements from [__first,
992 * __last).
993 *
994 * If the iterators are forward, bidirectional, or random-access, then
995 * this will call the elements' copy constructor N times (where N is
996 * distance(__first,__last)) and do no memory reallocation. But if only
997 * input iterators are used, then this will do at most 2N calls to the
998 * copy constructor, and logN memory reallocations.
999 */
1000 #if __cplusplus >= 201103L
1001 template<typename _InputIterator,
1002 typename = std::_RequireInputIter<_InputIterator>>
1003 deque(_InputIterator __first, _InputIterator __last,
1004 const allocator_type& __a = allocator_type())
1005 : _Base(__a)
1006 {
1007 _M_range_initialize(__first, __last,
1008 std::__iterator_category(__first));
1009 }
1010 #else
1011 template<typename _InputIterator>
1012 deque(_InputIterator __first, _InputIterator __last,
1013 const allocator_type& __a = allocator_type())
1014 : _Base(__a)
1015 {
1016 // Check whether it's an integral type. If so, it's not an iterator.
1017 typedef typename std::__is_integer<_InputIterator>::__type _Integral;
1018 _M_initialize_dispatch(__first, __last, _Integral());
1019 }
1020 #endif
1021
1022 /**
1023 * The dtor only erases the elements, and note that if the elements
1024 * themselves are pointers, the pointed-to memory is not touched in any
1025 * way. Managing the pointer is the user's responsibility.
1026 */
1027 ~deque()
1028 { _M_destroy_data(begin(), end(), _M_get_Tp_allocator()); }
1029
1030 /**
1031 * @brief %Deque assignment operator.
1032 * @param __x A %deque of identical element and allocator types.
1033 *
1034 * All the elements of @a x are copied.
1035 *
1036 * The newly-created %deque uses a copy of the allocator object used
1037 * by @a __x (unless the allocator traits dictate a different object).
1038 */
1039 deque&
1040 operator=(const deque& __x);
1041
1042 #if __cplusplus >= 201103L
1043 /**
1044 * @brief %Deque move assignment operator.
1045 * @param __x A %deque of identical element and allocator types.
1046 *
1047 * The contents of @a __x are moved into this deque (without copying,
1048 * if the allocators permit it).
1049 * @a __x is a valid, but unspecified %deque.
1050 */
1051 deque&
1052 operator=(deque&& __x) noexcept(_Alloc_traits::_S_always_equal())
1053 {
1054 using __always_equal = typename _Alloc_traits::is_always_equal;
1055 _M_move_assign1(std::move(__x), __always_equal{});
1056 return *this;
1057 }
1058
1059 /**
1060 * @brief Assigns an initializer list to a %deque.
1061 * @param __l An initializer_list.
1062 *
1063 * This function fills a %deque with copies of the elements in the
1064 * initializer_list @a __l.
1065 *
1066 * Note that the assignment completely changes the %deque and that the
1067 * resulting %deque's size is the same as the number of elements
1068 * assigned.
1069 */
1070 deque&
1071 operator=(initializer_list<value_type> __l)
1072 {
1073 _M_assign_aux(__l.begin(), __l.end(),
1074 random_access_iterator_tag());
1075 return *this;
1076 }
1077 #endif
1078
1079 /**
1080 * @brief Assigns a given value to a %deque.
1081 * @param __n Number of elements to be assigned.
1082 * @param __val Value to be assigned.
1083 *
1084 * This function fills a %deque with @a n copies of the given
1085 * value. Note that the assignment completely changes the
1086 * %deque and that the resulting %deque's size is the same as
1087 * the number of elements assigned.
1088 */
1089 void
1090 assign(size_type __n, const value_type& __val)
1091 { _M_fill_assign(__n, __val); }
1092
1093 /**
1094 * @brief Assigns a range to a %deque.
1095 * @param __first An input iterator.
1096 * @param __last An input iterator.
1097 *
1098 * This function fills a %deque with copies of the elements in the
1099 * range [__first,__last).
1100 *
1101 * Note that the assignment completely changes the %deque and that the
1102 * resulting %deque's size is the same as the number of elements
1103 * assigned.
1104 */
1105 #if __cplusplus >= 201103L
1106 template<typename _InputIterator,
1107 typename = std::_RequireInputIter<_InputIterator>>
1108 void
1109 assign(_InputIterator __first, _InputIterator __last)
1110 { _M_assign_aux(__first, __last, std::__iterator_category(__first)); }
1111 #else
1112 template<typename _InputIterator>
1113 void
1114 assign(_InputIterator __first, _InputIterator __last)
1115 {
1116 typedef typename std::__is_integer<_InputIterator>::__type _Integral;
1117 _M_assign_dispatch(__first, __last, _Integral());
1118 }
1119 #endif
1120
1121 #if __cplusplus >= 201103L
1122 /**
1123 * @brief Assigns an initializer list to a %deque.
1124 * @param __l An initializer_list.
1125 *
1126 * This function fills a %deque with copies of the elements in the
1127 * initializer_list @a __l.
1128 *
1129 * Note that the assignment completely changes the %deque and that the
1130 * resulting %deque's size is the same as the number of elements
1131 * assigned.
1132 */
1133 void
1134 assign(initializer_list<value_type> __l)
1135 { _M_assign_aux(__l.begin(), __l.end(), random_access_iterator_tag()); }
1136 #endif
1137
1138 /// Get a copy of the memory allocation object.
1139 _GLIBCXX_NODISCARD
1140 allocator_type
1141 get_allocator() const _GLIBCXX_NOEXCEPT
1142 { return _Base::get_allocator(); }
1143
1144 // iterators
1145 /**
1146 * Returns a read/write iterator that points to the first element in the
1147 * %deque. Iteration is done in ordinary element order.
1148 */
1149 _GLIBCXX_NODISCARD
1150 iterator
1151 begin() _GLIBCXX_NOEXCEPT
1152 { return this->_M_impl._M_start; }
1153
1154 /**
1155 * Returns a read-only (constant) iterator that points to the first
1156 * element in the %deque. Iteration is done in ordinary element order.
1157 */
1158 _GLIBCXX_NODISCARD
1159 const_iterator
1160 begin() const _GLIBCXX_NOEXCEPT
1161 { return this->_M_impl._M_start; }
1162
1163 /**
1164 * Returns a read/write iterator that points one past the last
1165 * element in the %deque. Iteration is done in ordinary
1166 * element order.
1167 */
1168 _GLIBCXX_NODISCARD
1169 iterator
1170 end() _GLIBCXX_NOEXCEPT
1171 { return this->_M_impl._M_finish; }
1172
1173 /**
1174 * Returns a read-only (constant) iterator that points one past
1175 * the last element in the %deque. Iteration is done in
1176 * ordinary element order.
1177 */
1178 _GLIBCXX_NODISCARD
1179 const_iterator
1180 end() const _GLIBCXX_NOEXCEPT
1181 { return this->_M_impl._M_finish; }
1182
1183 /**
1184 * Returns a read/write reverse iterator that points to the
1185 * last element in the %deque. Iteration is done in reverse
1186 * element order.
1187 */
1188 _GLIBCXX_NODISCARD
1189 reverse_iterator
1190 rbegin() _GLIBCXX_NOEXCEPT
1191 { return reverse_iterator(this->_M_impl._M_finish); }
1192
1193 /**
1194 * Returns a read-only (constant) reverse iterator that points
1195 * to the last element in the %deque. Iteration is done in
1196 * reverse element order.
1197 */
1198 _GLIBCXX_NODISCARD
1199 const_reverse_iterator
1200 rbegin() const _GLIBCXX_NOEXCEPT
1201 { return const_reverse_iterator(this->_M_impl._M_finish); }
1202
1203 /**
1204 * Returns a read/write reverse iterator that points to one
1205 * before the first element in the %deque. Iteration is done
1206 * in reverse element order.
1207 */
1208 _GLIBCXX_NODISCARD
1209 reverse_iterator
1210 rend() _GLIBCXX_NOEXCEPT
1211 { return reverse_iterator(this->_M_impl._M_start); }
1212
1213 /**
1214 * Returns a read-only (constant) reverse iterator that points
1215 * to one before the first element in the %deque. Iteration is
1216 * done in reverse element order.
1217 */
1218 _GLIBCXX_NODISCARD
1219 const_reverse_iterator
1220 rend() const _GLIBCXX_NOEXCEPT
1221 { return const_reverse_iterator(this->_M_impl._M_start); }
1222
1223 #if __cplusplus >= 201103L
1224 /**
1225 * Returns a read-only (constant) iterator that points to the first
1226 * element in the %deque. Iteration is done in ordinary element order.
1227 */
1228 [[__nodiscard__]]
1229 const_iterator
1230 cbegin() const noexcept
1231 { return this->_M_impl._M_start; }
1232
1233 /**
1234 * Returns a read-only (constant) iterator that points one past
1235 * the last element in the %deque. Iteration is done in
1236 * ordinary element order.
1237 */
1238 [[__nodiscard__]]
1239 const_iterator
1240 cend() const noexcept
1241 { return this->_M_impl._M_finish; }
1242
1243 /**
1244 * Returns a read-only (constant) reverse iterator that points
1245 * to the last element in the %deque. Iteration is done in
1246 * reverse element order.
1247 */
1248 [[__nodiscard__]]
1249 const_reverse_iterator
1250 crbegin() const noexcept
1251 { return const_reverse_iterator(this->_M_impl._M_finish); }
1252
1253 /**
1254 * Returns a read-only (constant) reverse iterator that points
1255 * to one before the first element in the %deque. Iteration is
1256 * done in reverse element order.
1257 */
1258 [[__nodiscard__]]
1259 const_reverse_iterator
1260 crend() const noexcept
1261 { return const_reverse_iterator(this->_M_impl._M_start); }
1262 #endif
1263
1264 // [23.2.1.2] capacity
1265 /** Returns the number of elements in the %deque. */
1266 _GLIBCXX_NODISCARD
1267 size_type
1268 size() const _GLIBCXX_NOEXCEPT
1269 { return this->_M_impl._M_finish - this->_M_impl._M_start; }
1270
1271 /** Returns the size() of the largest possible %deque. */
1272 _GLIBCXX_NODISCARD
1273 size_type
1274 max_size() const _GLIBCXX_NOEXCEPT
1275 { return _S_max_size(_M_get_Tp_allocator()); }
1276
1277 #if __cplusplus >= 201103L
1278 /**
1279 * @brief Resizes the %deque to the specified number of elements.
1280 * @param __new_size Number of elements the %deque should contain.
1281 *
1282 * This function will %resize the %deque to the specified
1283 * number of elements. If the number is smaller than the
1284 * %deque's current size the %deque is truncated, otherwise
1285 * default constructed elements are appended.
1286 */
1287 void
1288 resize(size_type __new_size)
1289 {
1290 const size_type __len = size();
1291 if (__new_size > __len)
1292 _M_default_append(__new_size - __len);
1293 else if (__new_size < __len)
1294 _M_erase_at_end(this->_M_impl._M_start
1295 + difference_type(__new_size));
1296 }
1297
1298 /**
1299 * @brief Resizes the %deque to the specified number of elements.
1300 * @param __new_size Number of elements the %deque should contain.
1301 * @param __x Data with which new elements should be populated.
1302 *
1303 * This function will %resize the %deque to the specified
1304 * number of elements. If the number is smaller than the
1305 * %deque's current size the %deque is truncated, otherwise the
1306 * %deque is extended and new elements are populated with given
1307 * data.
1308 */
1309 void
1310 resize(size_type __new_size, const value_type& __x)
1311 #else
1312 /**
1313 * @brief Resizes the %deque to the specified number of elements.
1314 * @param __new_size Number of elements the %deque should contain.
1315 * @param __x Data with which new elements should be populated.
1316 *
1317 * This function will %resize the %deque to the specified
1318 * number of elements. If the number is smaller than the
1319 * %deque's current size the %deque is truncated, otherwise the
1320 * %deque is extended and new elements are populated with given
1321 * data.
1322 */
1323 void
1324 resize(size_type __new_size, value_type __x = value_type())
1325 #endif
1326 {
1327 const size_type __len = size();
1328 if (__new_size > __len)
1329 _M_fill_insert(this->_M_impl._M_finish, __new_size - __len, __x);
1330 else if (__new_size < __len)
1331 _M_erase_at_end(this->_M_impl._M_start
1332 + difference_type(__new_size));
1333 }
1334
1335 #if __cplusplus >= 201103L
1336 /** A non-binding request to reduce memory use. */
1337 void
1338 shrink_to_fit() noexcept
1339 { _M_shrink_to_fit(); }
1340 #endif
1341
1342 /**
1343 * Returns true if the %deque is empty. (Thus begin() would
1344 * equal end().)
1345 */
1346 _GLIBCXX_NODISCARD bool
1347 empty() const _GLIBCXX_NOEXCEPT
1348 { return this->_M_impl._M_finish == this->_M_impl._M_start; }
1349
1350 // element access
1351 /**
1352 * @brief Subscript access to the data contained in the %deque.
1353 * @param __n The index of the element for which data should be
1354 * accessed.
1355 * @return Read/write reference to data.
1356 *
1357 * This operator allows for easy, array-style, data access.
1358 * Note that data access with this operator is unchecked and
1359 * out_of_range lookups are not defined. (For checked lookups
1360 * see at().)
1361 */
1362 _GLIBCXX_NODISCARD
1363 reference
1364 operator[](size_type __n) _GLIBCXX_NOEXCEPT
1365 {
1366 __glibcxx_requires_subscript(__n);
1367 return this->_M_impl._M_start[difference_type(__n)];
1368 }
1369
1370 /**
1371 * @brief Subscript access to the data contained in the %deque.
1372 * @param __n The index of the element for which data should be
1373 * accessed.
1374 * @return Read-only (constant) reference to data.
1375 *
1376 * This operator allows for easy, array-style, data access.
1377 * Note that data access with this operator is unchecked and
1378 * out_of_range lookups are not defined. (For checked lookups
1379 * see at().)
1380 */
1381 _GLIBCXX_NODISCARD
1382 const_reference
1383 operator[](size_type __n) const _GLIBCXX_NOEXCEPT
1384 {
1385 __glibcxx_requires_subscript(__n);
1386 return this->_M_impl._M_start[difference_type(__n)];
1387 }
1388
1389 protected:
1390 /// Safety check used only from at().
1391 void
1392 _M_range_check(size_type __n) const
1393 {
1394 if (__n >= this->size())
1395 __throw_out_of_range_fmt(__N("deque::_M_range_check: __n "
1396 "(which is %zu)>= this->size() "
1397 "(which is %zu)"),
1398 __n, this->size());
1399 }
1400
1401 public:
1402 /**
1403 * @brief Provides access to the data contained in the %deque.
1404 * @param __n The index of the element for which data should be
1405 * accessed.
1406 * @return Read/write reference to data.
1407 * @throw std::out_of_range If @a __n is an invalid index.
1408 *
1409 * This function provides for safer data access. The parameter
1410 * is first checked that it is in the range of the deque. The
1411 * function throws out_of_range if the check fails.
1412 */
1413 reference
1414 at(size_type __n)
1415 {
1416 _M_range_check(__n);
1417 return (*this)[__n];
1418 }
1419
1420 /**
1421 * @brief Provides access to the data contained in the %deque.
1422 * @param __n The index of the element for which data should be
1423 * accessed.
1424 * @return Read-only (constant) reference to data.
1425 * @throw std::out_of_range If @a __n is an invalid index.
1426 *
1427 * This function provides for safer data access. The parameter is first
1428 * checked that it is in the range of the deque. The function throws
1429 * out_of_range if the check fails.
1430 */
1431 const_reference
1432 at(size_type __n) const
1433 {
1434 _M_range_check(__n);
1435 return (*this)[__n];
1436 }
1437
1438 /**
1439 * Returns a read/write reference to the data at the first
1440 * element of the %deque.
1441 */
1442 _GLIBCXX_NODISCARD
1443 reference
1444 front() _GLIBCXX_NOEXCEPT
1445 {
1446 __glibcxx_requires_nonempty();
1447 return *begin();
1448 }
1449
1450 /**
1451 * Returns a read-only (constant) reference to the data at the first
1452 * element of the %deque.
1453 */
1454 _GLIBCXX_NODISCARD
1455 const_reference
1456 front() const _GLIBCXX_NOEXCEPT
1457 {
1458 __glibcxx_requires_nonempty();
1459 return *begin();
1460 }
1461
1462 /**
1463 * Returns a read/write reference to the data at the last element of the
1464 * %deque.
1465 */
1466 _GLIBCXX_NODISCARD
1467 reference
1468 back() _GLIBCXX_NOEXCEPT
1469 {
1470 __glibcxx_requires_nonempty();
1471 iterator __tmp = end();
1472 --__tmp;
1473 return *__tmp;
1474 }
1475
1476 /**
1477 * Returns a read-only (constant) reference to the data at the last
1478 * element of the %deque.
1479 */
1480 _GLIBCXX_NODISCARD
1481 const_reference
1482 back() const _GLIBCXX_NOEXCEPT
1483 {
1484 __glibcxx_requires_nonempty();
1485 const_iterator __tmp = end();
1486 --__tmp;
1487 return *__tmp;
1488 }
1489
1490 // [23.2.1.2] modifiers
1491 /**
1492 * @brief Add data to the front of the %deque.
1493 * @param __x Data to be added.
1494 *
1495 * This is a typical stack operation. The function creates an
1496 * element at the front of the %deque and assigns the given
1497 * data to it. Due to the nature of a %deque this operation
1498 * can be done in constant time.
1499 */
1500 void
1501 push_front(const value_type& __x)
1502 {
1503 if (this->_M_impl._M_start._M_cur != this->_M_impl._M_start._M_first)
1504 {
1505 _Alloc_traits::construct(this->_M_impl,
1506 this->_M_impl._M_start._M_cur - 1,
1507 __x);
1508 --this->_M_impl._M_start._M_cur;
1509 }
1510 else
1511 _M_push_front_aux(__x);
1512 }
1513
1514 #if __cplusplus >= 201103L
1515 void
1516 push_front(value_type&& __x)
1517 { emplace_front(std::move(__x)); }
1518
1519 template<typename... _Args>
1520 #if __cplusplus > 201402L
1521 reference
1522 #else
1523 void
1524 #endif
1525 emplace_front(_Args&&... __args);
1526 #endif
1527
1528 /**
1529 * @brief Add data to the end of the %deque.
1530 * @param __x Data to be added.
1531 *
1532 * This is a typical stack operation. The function creates an
1533 * element at the end of the %deque and assigns the given data
1534 * to it. Due to the nature of a %deque this operation can be
1535 * done in constant time.
1536 */
1537 void
1538 push_back(const value_type& __x)
1539 {
1540 if (this->_M_impl._M_finish._M_cur
1541 != this->_M_impl._M_finish._M_last - 1)
1542 {
1543 _Alloc_traits::construct(this->_M_impl,
1544 this->_M_impl._M_finish._M_cur, __x);
1545 ++this->_M_impl._M_finish._M_cur;
1546 }
1547 else
1548 _M_push_back_aux(__x);
1549 }
1550
1551 #if __cplusplus >= 201103L
1552 void
1553 push_back(value_type&& __x)
1554 { emplace_back(std::move(__x)); }
1555
1556 template<typename... _Args>
1557 #if __cplusplus > 201402L
1558 reference
1559 #else
1560 void
1561 #endif
1562 emplace_back(_Args&&... __args);
1563 #endif
1564
1565 /**
1566 * @brief Removes first element.
1567 *
1568 * This is a typical stack operation. It shrinks the %deque by one.
1569 *
1570 * Note that no data is returned, and if the first element's data is
1571 * needed, it should be retrieved before pop_front() is called.
1572 */
1573 void
1574 pop_front() _GLIBCXX_NOEXCEPT
1575 {
1576 __glibcxx_requires_nonempty();
1577 if (this->_M_impl._M_start._M_cur
1578 != this->_M_impl._M_start._M_last - 1)
1579 {
1580 _Alloc_traits::destroy(_M_get_Tp_allocator(),
1581 this->_M_impl._M_start._M_cur);
1582 ++this->_M_impl._M_start._M_cur;
1583 }
1584 else
1585 _M_pop_front_aux();
1586 }
1587
1588 /**
1589 * @brief Removes last element.
1590 *
1591 * This is a typical stack operation. It shrinks the %deque by one.
1592 *
1593 * Note that no data is returned, and if the last element's data is
1594 * needed, it should be retrieved before pop_back() is called.
1595 */
1596 void
1597 pop_back() _GLIBCXX_NOEXCEPT
1598 {
1599 __glibcxx_requires_nonempty();
1600 if (this->_M_impl._M_finish._M_cur
1601 != this->_M_impl._M_finish._M_first)
1602 {
1603 --this->_M_impl._M_finish._M_cur;
1604 _Alloc_traits::destroy(_M_get_Tp_allocator(),
1605 this->_M_impl._M_finish._M_cur);
1606 }
1607 else
1608 _M_pop_back_aux();
1609 }
1610
1611 #if __cplusplus >= 201103L
1612 /**
1613 * @brief Inserts an object in %deque before specified iterator.
1614 * @param __position A const_iterator into the %deque.
1615 * @param __args Arguments.
1616 * @return An iterator that points to the inserted data.
1617 *
1618 * This function will insert an object of type T constructed
1619 * with T(std::forward<Args>(args)...) before the specified location.
1620 */
1621 template<typename... _Args>
1622 iterator
1623 emplace(const_iterator __position, _Args&&... __args);
1624
1625 /**
1626 * @brief Inserts given value into %deque before specified iterator.
1627 * @param __position A const_iterator into the %deque.
1628 * @param __x Data to be inserted.
1629 * @return An iterator that points to the inserted data.
1630 *
1631 * This function will insert a copy of the given value before the
1632 * specified location.
1633 */
1634 iterator
1635 insert(const_iterator __position, const value_type& __x);
1636 #else
1637 /**
1638 * @brief Inserts given value into %deque before specified iterator.
1639 * @param __position An iterator into the %deque.
1640 * @param __x Data to be inserted.
1641 * @return An iterator that points to the inserted data.
1642 *
1643 * This function will insert a copy of the given value before the
1644 * specified location.
1645 */
1646 iterator
1647 insert(iterator __position, const value_type& __x);
1648 #endif
1649
1650 #if __cplusplus >= 201103L
1651 /**
1652 * @brief Inserts given rvalue into %deque before specified iterator.
1653 * @param __position A const_iterator into the %deque.
1654 * @param __x Data to be inserted.
1655 * @return An iterator that points to the inserted data.
1656 *
1657 * This function will insert a copy of the given rvalue before the
1658 * specified location.
1659 */
1660 iterator
1661 insert(const_iterator __position, value_type&& __x)
1662 { return emplace(__position, std::move(__x)); }
1663
1664 /**
1665 * @brief Inserts an initializer list into the %deque.
1666 * @param __p An iterator into the %deque.
1667 * @param __l An initializer_list.
1668 * @return An iterator that points to the inserted data.
1669 *
1670 * This function will insert copies of the data in the
1671 * initializer_list @a __l into the %deque before the location
1672 * specified by @a __p. This is known as <em>list insert</em>.
1673 */
1674 iterator
1675 insert(const_iterator __p, initializer_list<value_type> __l)
1676 {
1677 auto __offset = __p - cbegin();
1678 _M_range_insert_aux(__p._M_const_cast(), __l.begin(), __l.end(),
1679 std::random_access_iterator_tag());
1680 return begin() + __offset;
1681 }
1682
1683 /**
1684 * @brief Inserts a number of copies of given data into the %deque.
1685 * @param __position A const_iterator into the %deque.
1686 * @param __n Number of elements to be inserted.
1687 * @param __x Data to be inserted.
1688 * @return An iterator that points to the inserted data.
1689 *
1690 * This function will insert a specified number of copies of the given
1691 * data before the location specified by @a __position.
1692 */
1693 iterator
1694 insert(const_iterator __position, size_type __n, const value_type& __x)
1695 {
1696 difference_type __offset = __position - cbegin();
1697 _M_fill_insert(__position._M_const_cast(), __n, __x);
1698 return begin() + __offset;
1699 }
1700 #else
1701 /**
1702 * @brief Inserts a number of copies of given data into the %deque.
1703 * @param __position An iterator into the %deque.
1704 * @param __n Number of elements to be inserted.
1705 * @param __x Data to be inserted.
1706 *
1707 * This function will insert a specified number of copies of the given
1708 * data before the location specified by @a __position.
1709 */
1710 void
1711 insert(iterator __position, size_type __n, const value_type& __x)
1712 { _M_fill_insert(__position, __n, __x); }
1713 #endif
1714
1715 #if __cplusplus >= 201103L
1716 /**
1717 * @brief Inserts a range into the %deque.
1718 * @param __position A const_iterator into the %deque.
1719 * @param __first An input iterator.
1720 * @param __last An input iterator.
1721 * @return An iterator that points to the inserted data.
1722 *
1723 * This function will insert copies of the data in the range
1724 * [__first,__last) into the %deque before the location specified
1725 * by @a __position. This is known as <em>range insert</em>.
1726 */
1727 template<typename _InputIterator,
1728 typename = std::_RequireInputIter<_InputIterator>>
1729 iterator
1730 insert(const_iterator __position, _InputIterator __first,
1731 _InputIterator __last)
1732 {
1733 difference_type __offset = __position - cbegin();
1734 _M_range_insert_aux(__position._M_const_cast(), __first, __last,
1735 std::__iterator_category(__first));
1736 return begin() + __offset;
1737 }
1738 #else
1739 /**
1740 * @brief Inserts a range into the %deque.
1741 * @param __position An iterator into the %deque.
1742 * @param __first An input iterator.
1743 * @param __last An input iterator.
1744 *
1745 * This function will insert copies of the data in the range
1746 * [__first,__last) into the %deque before the location specified
1747 * by @a __position. This is known as <em>range insert</em>.
1748 */
1749 template<typename _InputIterator>
1750 void
1751 insert(iterator __position, _InputIterator __first,
1752 _InputIterator __last)
1753 {
1754 // Check whether it's an integral type. If so, it's not an iterator.
1755 typedef typename std::__is_integer<_InputIterator>::__type _Integral;
1756 _M_insert_dispatch(__position, __first, __last, _Integral());
1757 }
1758 #endif
1759
1760 /**
1761 * @brief Remove element at given position.
1762 * @param __position Iterator pointing to element to be erased.
1763 * @return An iterator pointing to the next element (or end()).
1764 *
1765 * This function will erase the element at the given position and thus
1766 * shorten the %deque by one.
1767 *
1768 * The user is cautioned that
1769 * this function only erases the element, and that if the element is
1770 * itself a pointer, the pointed-to memory is not touched in any way.
1771 * Managing the pointer is the user's responsibility.
1772 */
1773 iterator
1774 #if __cplusplus >= 201103L
1775 erase(const_iterator __position)
1776 #else
1777 erase(iterator __position)
1778 #endif
1779 { return _M_erase(__position._M_const_cast()); }
1780
1781 /**
1782 * @brief Remove a range of elements.
1783 * @param __first Iterator pointing to the first element to be erased.
1784 * @param __last Iterator pointing to one past the last element to be
1785 * erased.
1786 * @return An iterator pointing to the element pointed to by @a last
1787 * prior to erasing (or end()).
1788 *
1789 * This function will erase the elements in the range
1790 * [__first,__last) and shorten the %deque accordingly.
1791 *
1792 * The user is cautioned that
1793 * this function only erases the elements, and that if the elements
1794 * themselves are pointers, the pointed-to memory is not touched in any
1795 * way. Managing the pointer is the user's responsibility.
1796 */
1797 iterator
1798 #if __cplusplus >= 201103L
1799 erase(const_iterator __first, const_iterator __last)
1800 #else
1801 erase(iterator __first, iterator __last)
1802 #endif
1803 { return _M_erase(__first._M_const_cast(), __last._M_const_cast()); }
1804
1805 /**
1806 * @brief Swaps data with another %deque.
1807 * @param __x A %deque of the same element and allocator types.
1808 *
1809 * This exchanges the elements between two deques in constant time.
1810 * (Four pointers, so it should be quite fast.)
1811 * Note that the global std::swap() function is specialized such that
1812 * std::swap(d1,d2) will feed to this function.
1813 *
1814 * Whether the allocators are swapped depends on the allocator traits.
1815 */
1816 void
1817 swap(deque& __x) _GLIBCXX_NOEXCEPT
1818 {
1819 #if __cplusplus >= 201103L
1820 __glibcxx_assert(_Alloc_traits::propagate_on_container_swap::value
1821 || _M_get_Tp_allocator() == __x._M_get_Tp_allocator());
1822 #endif
1823 _M_impl._M_swap_data(__x._M_impl);
1824 _Alloc_traits::_S_on_swap(_M_get_Tp_allocator(),
1825 __x._M_get_Tp_allocator());
1826 }
1827
1828 /**
1829 * Erases all the elements. Note that this function only erases the
1830 * elements, and that if the elements themselves are pointers, the
1831 * pointed-to memory is not touched in any way. Managing the pointer is
1832 * the user's responsibility.
1833 */
1834 void
1835 clear() _GLIBCXX_NOEXCEPT
1836 { _M_erase_at_end(begin()); }
1837
1838 protected:
1839 // Internal constructor functions follow.
1840
1841 #if __cplusplus < 201103L
1842 // called by the range constructor to implement [23.1.1]/9
1843
1844 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1845 // 438. Ambiguity in the "do the right thing" clause
1846 template<typename _Integer>
1847 void
1848 _M_initialize_dispatch(_Integer __n, _Integer __x, __true_type)
1849 {
1850 _M_initialize_map(_S_check_init_len(static_cast<size_type>(__n),
1851 _M_get_Tp_allocator()));
1852 _M_fill_initialize(__x);
1853 }
1854
1855 // called by the range constructor to implement [23.1.1]/9
1856 template<typename _InputIterator>
1857 void
1858 _M_initialize_dispatch(_InputIterator __first, _InputIterator __last,
1859 __false_type)
1860 {
1861 _M_range_initialize(__first, __last,
1862 std::__iterator_category(__first));
1863 }
1864 #endif
1865
1866 static size_t
1867 _S_check_init_len(size_t __n, const allocator_type& __a)
1868 {
1869 if (__n > _S_max_size(__a))
1870 __throw_length_error(
1871 __N("cannot create std::deque larger than max_size()"));
1872 return __n;
1873 }
1874
1875 static size_type
1876 _S_max_size(const _Tp_alloc_type& __a) _GLIBCXX_NOEXCEPT
1877 {
1878 const size_t __diffmax = __gnu_cxx::__numeric_traits<ptrdiff_t>::__max;
1879 const size_t __allocmax = _Alloc_traits::max_size(__a);
1880 return (std::min)(__diffmax, __allocmax);
1881 }
1882
1883 // called by the second initialize_dispatch above
1884 ///@{
1885 /**
1886 * @brief Fills the deque with whatever is in [first,last).
1887 * @param __first An input iterator.
1888 * @param __last An input iterator.
1889 * @return Nothing.
1890 *
1891 * If the iterators are actually forward iterators (or better), then the
1892 * memory layout can be done all at once. Else we move forward using
1893 * push_back on each value from the iterator.
1894 */
1895 template<typename _InputIterator>
1896 void
1897 _M_range_initialize(_InputIterator __first, _InputIterator __last,
1898 std::input_iterator_tag);
1899
1900 // called by the second initialize_dispatch above
1901 template<typename _ForwardIterator>
1902 void
1903 _M_range_initialize(_ForwardIterator __first, _ForwardIterator __last,
1904 std::forward_iterator_tag);
1905 ///@}
1906
1907 /**
1908 * @brief Fills the %deque with copies of value.
1909 * @param __value Initial value.
1910 * @return Nothing.
1911 * @pre _M_start and _M_finish have already been initialized,
1912 * but none of the %deque's elements have yet been constructed.
1913 *
1914 * This function is called only when the user provides an explicit size
1915 * (with or without an explicit exemplar value).
1916 */
1917 void
1918 _M_fill_initialize(const value_type& __value);
1919
1920 #if __cplusplus >= 201103L
1921 // called by deque(n).
1922 void
1923 _M_default_initialize();
1924 #endif
1925
1926 // Internal assign functions follow. The *_aux functions do the actual
1927 // assignment work for the range versions.
1928
1929 #if __cplusplus < 201103L
1930 // called by the range assign to implement [23.1.1]/9
1931
1932 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1933 // 438. Ambiguity in the "do the right thing" clause
1934 template<typename _Integer>
1935 void
1936 _M_assign_dispatch(_Integer __n, _Integer __val, __true_type)
1937 { _M_fill_assign(__n, __val); }
1938
1939 // called by the range assign to implement [23.1.1]/9
1940 template<typename _InputIterator>
1941 void
1942 _M_assign_dispatch(_InputIterator __first, _InputIterator __last,
1943 __false_type)
1944 { _M_assign_aux(__first, __last, std::__iterator_category(__first)); }
1945 #endif
1946
1947 // called by the second assign_dispatch above
1948 template<typename _InputIterator>
1949 void
1950 _M_assign_aux(_InputIterator __first, _InputIterator __last,
1951 std::input_iterator_tag);
1952
1953 // called by the second assign_dispatch above
1954 template<typename _ForwardIterator>
1955 void
1956 _M_assign_aux(_ForwardIterator __first, _ForwardIterator __last,
1957 std::forward_iterator_tag)
1958 {
1959 const size_type __len = std::distance(__first, __last);
1960 if (__len > size())
1961 {
1962 _ForwardIterator __mid = __first;
1963 std::advance(__mid, size());
1964 std::copy(__first, __mid, begin());
1965 _M_range_insert_aux(end(), __mid, __last,
1966 std::__iterator_category(__first));
1967 }
1968 else
1969 _M_erase_at_end(std::copy(__first, __last, begin()));
1970 }
1971
1972 // Called by assign(n,t), and the range assign when it turns out
1973 // to be the same thing.
1974 void
1975 _M_fill_assign(size_type __n, const value_type& __val)
1976 {
1977 if (__n > size())
1978 {
1979 std::fill(begin(), end(), __val);
1980 _M_fill_insert(end(), __n - size(), __val);
1981 }
1982 else
1983 {
1984 _M_erase_at_end(begin() + difference_type(__n));
1985 std::fill(begin(), end(), __val);
1986 }
1987 }
1988
1989 ///@{
1990 /// Helper functions for push_* and pop_*.
1991 #if __cplusplus < 201103L
1992 void _M_push_back_aux(const value_type&);
1993
1994 void _M_push_front_aux(const value_type&);
1995 #else
1996 template<typename... _Args>
1997 void _M_push_back_aux(_Args&&... __args);
1998
1999 template<typename... _Args>
2000 void _M_push_front_aux(_Args&&... __args);
2001 #endif
2002
2003 void _M_pop_back_aux();
2004
2005 void _M_pop_front_aux();
2006 ///@}
2007
2008 // Internal insert functions follow. The *_aux functions do the actual
2009 // insertion work when all shortcuts fail.
2010
2011 #if __cplusplus < 201103L
2012 // called by the range insert to implement [23.1.1]/9
2013
2014 // _GLIBCXX_RESOLVE_LIB_DEFECTS
2015 // 438. Ambiguity in the "do the right thing" clause
2016 template<typename _Integer>
2017 void
2018 _M_insert_dispatch(iterator __pos,
2019 _Integer __n, _Integer __x, __true_type)
2020 { _M_fill_insert(__pos, __n, __x); }
2021
2022 // called by the range insert to implement [23.1.1]/9
2023 template<typename _InputIterator>
2024 void
2025 _M_insert_dispatch(iterator __pos,
2026 _InputIterator __first, _InputIterator __last,
2027 __false_type)
2028 {
2029 _M_range_insert_aux(__pos, __first, __last,
2030 std::__iterator_category(__first));
2031 }
2032 #endif
2033
2034 // called by the second insert_dispatch above
2035 template<typename _InputIterator>
2036 void
2037 _M_range_insert_aux(iterator __pos, _InputIterator __first,
2038 _InputIterator __last, std::input_iterator_tag);
2039
2040 // called by the second insert_dispatch above
2041 template<typename _ForwardIterator>
2042 void
2043 _M_range_insert_aux(iterator __pos, _ForwardIterator __first,
2044 _ForwardIterator __last, std::forward_iterator_tag);
2045
2046 // Called by insert(p,n,x), and the range insert when it turns out to be
2047 // the same thing. Can use fill functions in optimal situations,
2048 // otherwise passes off to insert_aux(p,n,x).
2049 void
2050 _M_fill_insert(iterator __pos, size_type __n, const value_type& __x);
2051
2052 // called by insert(p,x)
2053 #if __cplusplus < 201103L
2054 iterator
2055 _M_insert_aux(iterator __pos, const value_type& __x);
2056 #else
2057 template<typename... _Args>
2058 iterator
2059 _M_insert_aux(iterator __pos, _Args&&... __args);
2060 #endif
2061
2062 // called by insert(p,n,x) via fill_insert
2063 void
2064 _M_insert_aux(iterator __pos, size_type __n, const value_type& __x);
2065
2066 // called by range_insert_aux for forward iterators
2067 template<typename _ForwardIterator>
2068 void
2069 _M_insert_aux(iterator __pos,
2070 _ForwardIterator __first, _ForwardIterator __last,
2071 size_type __n);
2072
2073
2074 // Internal erase functions follow.
2075
2076 void
2077 _M_destroy_data_aux(iterator __first, iterator __last);
2078
2079 // Called by ~deque().
2080 // NB: Doesn't deallocate the nodes.
2081 template<typename _Alloc1>
2082 void
2083 _M_destroy_data(iterator __first, iterator __last, const _Alloc1&)
2084 { _M_destroy_data_aux(__first, __last); }
2085
2086 void
2087 _M_destroy_data(iterator __first, iterator __last,
2088 const std::allocator<_Tp>&)
2089 {
2090 if (!__has_trivial_destructor(value_type))
2091 _M_destroy_data_aux(__first, __last);
2092 }
2093
2094 // Called by erase(q1, q2).
2095 void
2096 _M_erase_at_begin(iterator __pos)
2097 {
2098 _M_destroy_data(begin(), __pos, _M_get_Tp_allocator());
2099 _M_destroy_nodes(this->_M_impl._M_start._M_node, __pos._M_node);
2100 this->_M_impl._M_start = __pos;
2101 }
2102
2103 // Called by erase(q1, q2), resize(), clear(), _M_assign_aux,
2104 // _M_fill_assign, operator=.
2105 void
2106 _M_erase_at_end(iterator __pos)
2107 {
2108 _M_destroy_data(__pos, end(), _M_get_Tp_allocator());
2109 _M_destroy_nodes(__pos._M_node + 1,
2110 this->_M_impl._M_finish._M_node + 1);
2111 this->_M_impl._M_finish = __pos;
2112 }
2113
2114 iterator
2115 _M_erase(iterator __pos);
2116
2117 iterator
2118 _M_erase(iterator __first, iterator __last);
2119
2120 #if __cplusplus >= 201103L
2121 // Called by resize(sz).
2122 void
2123 _M_default_append(size_type __n);
2124
2125 bool
2126 _M_shrink_to_fit();
2127 #endif
2128
2129 ///@{
2130 /// Memory-handling helpers for the previous internal insert functions.
2131 iterator
2132 _M_reserve_elements_at_front(size_type __n)
2133 {
2134 const size_type __vacancies = this->_M_impl._M_start._M_cur
2135 - this->_M_impl._M_start._M_first;
2136 if (__n > __vacancies)
2137 _M_new_elements_at_front(__n - __vacancies);
2138 return this->_M_impl._M_start - difference_type(__n);
2139 }
2140
2141 iterator
2142 _M_reserve_elements_at_back(size_type __n)
2143 {
2144 const size_type __vacancies = (this->_M_impl._M_finish._M_last
2145 - this->_M_impl._M_finish._M_cur) - 1;
2146 if (__n > __vacancies)
2147 _M_new_elements_at_back(__n - __vacancies);
2148 return this->_M_impl._M_finish + difference_type(__n);
2149 }
2150
2151 void
2152 _M_new_elements_at_front(size_type __new_elements);
2153
2154 void
2155 _M_new_elements_at_back(size_type __new_elements);
2156 ///@}
2157
2158
2159 ///@{
2160 /**
2161 * @brief Memory-handling helpers for the major %map.
2162 *
2163 * Makes sure the _M_map has space for new nodes. Does not
2164 * actually add the nodes. Can invalidate _M_map pointers.
2165 * (And consequently, %deque iterators.)
2166 */
2167 void
2168 _M_reserve_map_at_back(size_type __nodes_to_add = 1)
2169 {
2170 if (__nodes_to_add + 1 > this->_M_impl._M_map_size
2171 - (this->_M_impl._M_finish._M_node - this->_M_impl._M_map))
2172 _M_reallocate_map(__nodes_to_add, false);
2173 }
2174
2175 void
2176 _M_reserve_map_at_front(size_type __nodes_to_add = 1)
2177 {
2178 if (__nodes_to_add > size_type(this->_M_impl._M_start._M_node
2179 - this->_M_impl._M_map))
2180 _M_reallocate_map(__nodes_to_add, true);
2181 }
2182
2183 void
2184 _M_reallocate_map(size_type __nodes_to_add, bool __add_at_front);
2185 ///@}
2186
2187 #if __cplusplus >= 201103L
2188 // Constant-time, nothrow move assignment when source object's memory
2189 // can be moved because the allocators are equal.
2190 void
2191 _M_move_assign1(deque&& __x, /* always equal: */ true_type) noexcept
2192 {
2193 this->_M_impl._M_swap_data(__x._M_impl);
2194 __x.clear();
2195 std::__alloc_on_move(_M_get_Tp_allocator(), __x._M_get_Tp_allocator());
2196 }
2197
2198 // When the allocators are not equal the operation could throw, because
2199 // we might need to allocate a new map for __x after moving from it
2200 // or we might need to allocate new elements for *this.
2201 void
2202 _M_move_assign1(deque&& __x, /* always equal: */ false_type)
2203 {
2204 if (_M_get_Tp_allocator() == __x._M_get_Tp_allocator())
2205 return _M_move_assign1(std::move(__x), true_type());
2206
2207 constexpr bool __move_storage =
2208 _Alloc_traits::_S_propagate_on_move_assign();
2209 _M_move_assign2(std::move(__x), __bool_constant<__move_storage>());
2210 }
2211
2212 // Destroy all elements and deallocate all memory, then replace
2213 // with elements created from __args.
2214 template<typename... _Args>
2215 void
2216 _M_replace_map(_Args&&... __args)
2217 {
2218 // Create new data first, so if allocation fails there are no effects.
2219 deque __newobj(std::forward<_Args>(__args)...);
2220 // Free existing storage using existing allocator.
2221 clear();
2222 _M_deallocate_node(*begin()._M_node); // one node left after clear()
2223 _M_deallocate_map(this->_M_impl._M_map, this->_M_impl._M_map_size);
2224 this->_M_impl._M_map = nullptr;
2225 this->_M_impl._M_map_size = 0;
2226 // Take ownership of replacement memory.
2227 this->_M_impl._M_swap_data(__newobj._M_impl);
2228 }
2229
2230 // Do move assignment when the allocator propagates.
2231 void
2232 _M_move_assign2(deque&& __x, /* propagate: */ true_type)
2233 {
2234 // Make a copy of the original allocator state.
2235 auto __alloc = __x._M_get_Tp_allocator();
2236 // The allocator propagates so storage can be moved from __x,
2237 // leaving __x in a valid empty state with a moved-from allocator.
2238 _M_replace_map(std::move(__x));
2239 // Move the corresponding allocator state too.
2240 _M_get_Tp_allocator() = std::move(__alloc);
2241 }
2242
2243 // Do move assignment when it may not be possible to move source
2244 // object's memory, resulting in a linear-time operation.
2245 void
2246 _M_move_assign2(deque&& __x, /* propagate: */ false_type)
2247 {
2248 if (__x._M_get_Tp_allocator() == this->_M_get_Tp_allocator())
2249 {
2250 // The allocators are equal so storage can be moved from __x,
2251 // leaving __x in a valid empty state with its current allocator.
2252 _M_replace_map(std::move(__x), __x.get_allocator());
2253 }
2254 else
2255 {
2256 // The rvalue's allocator cannot be moved and is not equal,
2257 // so we need to individually move each element.
2258 _M_assign_aux(std::make_move_iterator(__x.begin()),
2259 std::make_move_iterator(__x.end()),
2260 std::random_access_iterator_tag());
2261 __x.clear();
2262 }
2263 }
2264 #endif
2265 };
2266
2267 #if __cpp_deduction_guides >= 201606
2268 template<typename _InputIterator, typename _ValT
2269 = typename iterator_traits<_InputIterator>::value_type,
2270 typename _Allocator = allocator<_ValT>,
2271 typename = _RequireInputIter<_InputIterator>,
2272 typename = _RequireAllocator<_Allocator>>
2273 deque(_InputIterator, _InputIterator, _Allocator = _Allocator())
2274 -> deque<_ValT, _Allocator>;
2275 #endif
2276
2277 /**
2278 * @brief Deque equality comparison.
2279 * @param __x A %deque.
2280 * @param __y A %deque of the same type as @a __x.
2281 * @return True iff the size and elements of the deques are equal.
2282 *
2283 * This is an equivalence relation. It is linear in the size of the
2284 * deques. Deques are considered equivalent if their sizes are equal,
2285 * and if corresponding elements compare equal.
2286 */
2287 template<typename _Tp, typename _Alloc>
2288 _GLIBCXX_NODISCARD
2289 inline bool
2290 operator==(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2291 { return __x.size() == __y.size()
2292 && std::equal(__x.begin(), __x.end(), __y.begin()); }
2293
2294 #if __cpp_lib_three_way_comparison
2295 /**
2296 * @brief Deque ordering relation.
2297 * @param __x A `deque`.
2298 * @param __y A `deque` of the same type as `__x`.
2299 * @return A value indicating whether `__x` is less than, equal to,
2300 * greater than, or incomparable with `__y`.
2301 *
2302 * See `std::lexicographical_compare_three_way()` for how the determination
2303 * is made. This operator is used to synthesize relational operators like
2304 * `<` and `>=` etc.
2305 */
2306 template<typename _Tp, typename _Alloc>
2307 [[nodiscard]]
2308 inline __detail::__synth3way_t<_Tp>
2309 operator<=>(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2310 {
2311 return std::lexicographical_compare_three_way(__x.begin(), __x.end(),
2312 __y.begin(), __y.end(),
2313 __detail::__synth3way);
2314 }
2315 #else
2316 /**
2317 * @brief Deque ordering relation.
2318 * @param __x A %deque.
2319 * @param __y A %deque of the same type as @a __x.
2320 * @return True iff @a x is lexicographically less than @a __y.
2321 *
2322 * This is a total ordering relation. It is linear in the size of the
2323 * deques. The elements must be comparable with @c <.
2324 *
2325 * See std::lexicographical_compare() for how the determination is made.
2326 */
2327 template<typename _Tp, typename _Alloc>
2328 _GLIBCXX_NODISCARD
2329 inline bool
2330 operator<(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2331 { return std::lexicographical_compare(__x.begin(), __x.end(),
2332 __y.begin(), __y.end()); }
2333
2334 /// Based on operator==
2335 template<typename _Tp, typename _Alloc>
2336 _GLIBCXX_NODISCARD
2337 inline bool
2338 operator!=(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2339 { return !(__x == __y); }
2340
2341 /// Based on operator<
2342 template<typename _Tp, typename _Alloc>
2343 _GLIBCXX_NODISCARD
2344 inline bool
2345 operator>(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2346 { return __y < __x; }
2347
2348 /// Based on operator<
2349 template<typename _Tp, typename _Alloc>
2350 _GLIBCXX_NODISCARD
2351 inline bool
2352 operator<=(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2353 { return !(__y < __x); }
2354
2355 /// Based on operator<
2356 template<typename _Tp, typename _Alloc>
2357 _GLIBCXX_NODISCARD
2358 inline bool
2359 operator>=(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2360 { return !(__x < __y); }
2361 #endif // three-way comparison
2362
2363 /// See std::deque::swap().
2364 template<typename _Tp, typename _Alloc>
2365 inline void
2366 swap(deque<_Tp,_Alloc>& __x, deque<_Tp,_Alloc>& __y)
2367 _GLIBCXX_NOEXCEPT_IF(noexcept(__x.swap(__y)))
2368 { __x.swap(__y); }
2369
2370 #undef _GLIBCXX_DEQUE_BUF_SIZE
2371
2372 _GLIBCXX_END_NAMESPACE_CONTAINER
2373
2374 #if __cplusplus >= 201103L
2375 // std::allocator is safe, but it is not the only allocator
2376 // for which this is valid.
2377 template<class _Tp>
2378 struct __is_bitwise_relocatable<_GLIBCXX_STD_C::deque<_Tp>>
2379 : true_type { };
2380 #endif
2381
2382 _GLIBCXX_END_NAMESPACE_VERSION
2383 } // namespace std
2384
2385 #endif /* _STL_DEQUE_H */