stl_deque.h source code [include/c++/11/bits/stl_deque.h]

1	// Deque implementation -- C++ --
2
3	// Copyright (C) 2001-2021 Free Software Foundation, Inc.
4	//
5	// This file is part of the GNU ISO C++ Library. This library is free
6	// software; you can redistribute it and/or modify it under the
7	// terms of the GNU General Public License as published by the
8	// Free Software Foundation; either version 3, or (at your option)
9	// any later version.
10
11	// This library is distributed in the hope that it will be useful,
12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14	// GNU General Public License for more details.
15
16	// Under Section 7 of GPL version 3, you are granted additional
17	// permissions described in the GCC Runtime Library Exception, version
18	// 3.1, as published by the Free Software Foundation.
19
20	// You should have received a copy of the GNU General Public License and
21	// a copy of the GCC Runtime Library Exception along with this program;
22	// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23	// <http://www.gnu.org/licenses/>.
24
25	/*
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(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	reference
180	operator() const* _GLIBCXX_NOEXCEPT
181	{ return *_M_cur; }
182
183	pointer
184	operator->() const _GLIBCXX_NOEXCEPT
185	{ return _M_cur; }
186
187	_Self&
188	operator++() _GLIBCXX_NOEXCEPT
189	{
190	++_M_cur;
191	if (_M_cur == _M_last)
192	{
193	_M_set_node(new_node: _M_node + `1`);
194	_M_cur = _M_first;
195	}
196	return *this;
197	}
198
199	_Self
200	operator++(int) _GLIBCXX_NOEXCEPT
201	{
202	_Self __tmp = *this;
203	++*this;
204	return __tmp;
205	}
206
207	_Self&
208	operator--() _GLIBCXX_NOEXCEPT
209	{
210	if (_M_cur == _M_first)
211	{
212	_M_set_node(new_node: _M_node - `1`);
213	_M_cur = _M_last;
214	}
215	--_M_cur;
216	return *this;
217	}
218
219	_Self
220	operator--(int) _GLIBCXX_NOEXCEPT
221	{
222	_Self __tmp = *this;
223	--*this;
224	return __tmp;
225	}
226
227	_Self&
228	operator+=(difference_type __n) _GLIBCXX_NOEXCEPT
229	{
230	const difference_type __offset = __n + (_M_cur - _M_first);
231	if (__offset >= `0` && __offset < difference_type(_S_buffer_size()))
232	_M_cur += __n;
233	else
234	{
235	const difference_type __node_offset =
236	__offset > `0` ? __offset / difference_type(_S_buffer_size())
237	: -difference_type((-__offset - `1`)
238	/ _S_buffer_size()) - `1`;
239	_M_set_node(new_node: _M_node + __node_offset);
240	_M_cur = _M_first + (__offset - __node_offset
241	* difference_type(_S_buffer_size()));
242	}
243	return *this;
244	}
245
246	_Self&
247	operator-=(difference_type __n) _GLIBCXX_NOEXCEPT
248	{ return *this += -__n; }
249
250	reference
251	operator[](difference_type __n) const _GLIBCXX_NOEXCEPT
252	{ return (this + __n); }
253
254	/**
255	* Prepares to traverse new_node. Sets everything except
256	* _M_cur, which should therefore be set by the caller
257	* immediately afterwards, based on _M_first and _M_last.
258	*/
259	void
260	_M_set_node(_Map_pointer __new_node) _GLIBCXX_NOEXCEPT
261	{
262	_M_node = __new_node;
263	_M_first = *__new_node;
264	_M_last = _M_first + difference_type(_S_buffer_size());
265	}
266
267	friend bool
268	operator==(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
269	{ return __x._M_cur == __y._M_cur; }
270
271	// Note: we also provide overloads whose operands are of the same type in
272	// order to avoid ambiguous overload resolution when std::rel_ops
273	// operators are in scope (for additional details, see libstdc++/3628)
274	template<typename _RefR, typename _PtrR>
275	friend bool
276	operator==(const _Self& __x,
277	const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
278	_GLIBCXX_NOEXCEPT
279	{ return __x._M_cur == __y._M_cur; }
280
281	#if __cpp_lib_three_way_comparison
282	friend strong_ordering
283	operator<=>(const _Self& __x, const _Self& __y) noexcept
284	{
285	if (const auto __cmp = __x._M_node <=> __y._M_node; __cmp != `0`)
286	return __cmp;
287	return __x._M_cur <=> __y._M_cur;
288	}
289	#else
290	friend bool
291	operator!=(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
292	{ return !(__x == __y); }
293
294	template<typename _RefR, typename _PtrR>
295	friend bool
296	operator!=(const _Self& __x,
297	const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
298	_GLIBCXX_NOEXCEPT
299	{ return !(__x == __y); }
300
301	friend bool
302	operator<(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
303	{
304	return (__x._M_node == __y._M_node)
305	? (__x._M_cur < __y._M_cur) : (__x._M_node < __y._M_node);
306	}
307
308	template<typename _RefR, typename _PtrR>
309	friend bool
310	operator<(const _Self& __x,
311	const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
312	_GLIBCXX_NOEXCEPT
313	{
314	return (__x._M_node == __y._M_node)
315	? (__x._M_cur < __y._M_cur) : (__x._M_node < __y._M_node);
316	}
317
318	friend bool
319	operator>(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
320	{ return __y < __x; }
321
322	template<typename _RefR, typename _PtrR>
323	friend bool
324	operator>(const _Self& __x,
325	const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
326	_GLIBCXX_NOEXCEPT
327	{ return __y < __x; }
328
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	friend bool
335	operator<=(const _Self& __x,
336	const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
337	_GLIBCXX_NOEXCEPT
338	{ return !(__y < __x); }
339
340	friend bool
341	operator>=(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
342	{ return !(__x < __y); }
343
344	template<typename _RefR, typename _PtrR>
345	friend bool
346	operator>=(const _Self& __x,
347	const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
348	_GLIBCXX_NOEXCEPT
349	{ return !(__x < __y); }
350	#endif // three-way comparison
351
352	friend difference_type
353	operator-(const _Self& __x, const _Self& __y) _GLIBCXX_NOEXCEPT
354	{
355	return difference_type(_S_buffer_size())
356	* (__x._M_node - __y._M_node - bool(__x._M_node))
357	+ (__x._M_cur - __x._M_first)
358	+ (__y._M_last - __y._M_cur);
359	}
360
361	// _GLIBCXX_RESOLVE_LIB_DEFECTS
362	// According to the resolution of DR179 not only the various comparison
363	// operators but also operator- must accept mixed iterator/const_iterator
364	// parameters.
365	template<typename _RefR, typename _PtrR>
366	friend difference_type
367	operator-(const _Self& __x,
368	const _Deque_iterator<_Tp, _RefR, _PtrR>& __y)
369	_GLIBCXX_NOEXCEPT
370	{
371	return difference_type(_S_buffer_size())
372	* (__x._M_node - __y._M_node - bool(__x._M_node))
373	+ (__x._M_cur - __x._M_first)
374	+ (__y._M_last - __y._M_cur);
375	}
376
377	friend _Self
378	operator+(const _Self& __x, difference_type __n) _GLIBCXX_NOEXCEPT
379	{
380	_Self __tmp = __x;
381	__tmp += __n;
382	return __tmp;
383	}
384
385	friend _Self
386	operator-(const _Self& __x, difference_type __n) _GLIBCXX_NOEXCEPT
387	{
388	_Self __tmp = __x;
389	__tmp -= __n;
390	return __tmp;
391	}
392
393	friend _Self
394	operator+(difference_type __n, const _Self& __x) _GLIBCXX_NOEXCEPT
395	{ return __x + __n; }
396	};
397
398	/**
399	* Deque base class. This class provides the unified face for %deque's
400	* allocation. This class's constructor and destructor allocate and
401	* deallocate (but do not initialize) storage. This makes %exception
402	* safety easier.
403	*
404	* Nothing in this class ever constructs or destroys an actual Tp element.
405	* (Deque handles that itself.) Only/All memory management is performed
406	* here.
407	*/
408	template<typename _Tp, typename _Alloc>
409	class _Deque_base
410	{
411	protected:
412	typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
413	rebind<_Tp>::other _Tp_alloc_type;
414	typedef __gnu_cxx::__alloc_traits<_Tp_alloc_type> _Alloc_traits;
415
416	#if __cplusplus < 201103L
417	typedef _Tp* _Ptr;
418	typedef const _Tp* _Ptr_const;
419	#else
420	typedef typename _Alloc_traits::pointer _Ptr;
421	typedef typename _Alloc_traits::const_pointer _Ptr_const;
422	#endif
423
424	typedef typename _Alloc_traits::template rebind<_Ptr>::other
425	_Map_alloc_type;
426	typedef __gnu_cxx::__alloc_traits<_Map_alloc_type> _Map_alloc_traits;
427
428	typedef _Alloc allocator_type;
429
430	allocator_type
431	get_allocator() const _GLIBCXX_NOEXCEPT
432	{ return allocator_type(_M_get_Tp_allocator()); }
433
434	typedef _Deque_iterator<_Tp, _Tp&, _Ptr> iterator;
435	typedef _Deque_iterator<_Tp, const _Tp&, _Ptr_const> const_iterator;
436
437	_Deque_base()
438	: _M_impl()
439	{ _M_initialize_map(`0`); }
440
441	_Deque_base(size_t __num_elements)
442	: _M_impl()
443	{ _M_initialize_map(__num_elements); }
444
445	_Deque_base(const allocator_type& __a, size_t __num_elements)
446	: _M_impl(__a)
447	{ _M_initialize_map(__num_elements); }
448
449	_Deque_base(const allocator_type& __a)
450	: _M_impl(__a)
451	{ / Caller must initialize map. / }
452
453	#if __cplusplus >= 201103L
454	_Deque_base(_Deque_base&& __x)
455	: _M_impl(std::move(__x._M_get_Tp_allocator()))
456	{
457	_M_initialize_map(`0`);
458	if (__x._M_impl._M_map)
459	this->_M_impl._M_swap_data(__x._M_impl);
460	}
461
462	_Deque_base(_Deque_base&& __x, const allocator_type& __a)
463	: _M_impl(std::move(__x._M_impl), _Tp_alloc_type(__a))
464	{ __x._M_initialize_map(`0`); }
465
466	_Deque_base(_Deque_base&& __x, const allocator_type& __a, size_t __n)
467	: _M_impl(__a)
468	{
469	if (__x.get_allocator() == __a)
470	{
471	if (__x._M_impl._M_map)
472	{
473	_M_initialize_map(`0`);
474	this->_M_impl._M_swap_data(__x._M_impl);
475	}
476	}
477	else
478	{
479	_M_initialize_map(__n);
480	}
481	}
482	#endif
483
484	~_Deque_base() _GLIBCXX_NOEXCEPT;
485
486	typedef typename iterator::_Map_pointer _Map_pointer;
487
488	struct _Deque_impl_data
489	{
490	_Map_pointer _M_map;
491	size_t _M_map_size;
492	iterator _M_start;
493	iterator _M_finish;
494
495	_Deque_impl_data() _GLIBCXX_NOEXCEPT
496	: _M_map(), _M_map_size(), _M_start(), _M_finish()
497	{ }
498
499	#if __cplusplus >= 201103L
500	_Deque_impl_data(const _Deque_impl_data&) = default;
501	_Deque_impl_data&
502	operator=(const _Deque_impl_data&) = default;
503
504	_Deque_impl_data(_Deque_impl_data&& __x) noexcept
505	: _Deque_impl_data(__x)
506	{ __x = _Deque_impl_data(); }
507	#endif
508
509	void
510	_M_swap_data(_Deque_impl_data& __x) _GLIBCXX_NOEXCEPT
511	{
512	// Do not use std::swap(_M_start, __x._M_start), etc as it loses
513	// information used by TBAA.
514	std::swap(*this, __x);
515	}
516	};
517
518	// This struct encapsulates the implementation of the std::deque
519	// standard container and at the same time makes use of the EBO
520	// for empty allocators.
521	struct _Deque_impl
522	: public _Tp_alloc_type, public _Deque_impl_data
523	{
524	_Deque_impl() _GLIBCXX_NOEXCEPT_IF(
525	is_nothrow_default_constructible<_Tp_alloc_type>::value)
526	: _Tp_alloc_type()
527	{ }
528
529	_Deque_impl(const _Tp_alloc_type& __a) _GLIBCXX_NOEXCEPT
530	: _Tp_alloc_type(__a)
531	{ }
532
533	#if __cplusplus >= 201103L
534	_Deque_impl(_Deque_impl&&) = default;
535
536	_Deque_impl(_Tp_alloc_type&& __a) noexcept
537	: _Tp_alloc_type(std::move(__a))
538	{ }
539
540	_Deque_impl(_Deque_impl&& __d, _Tp_alloc_type&& __a)
541	: _Tp_alloc_type(std::move(__a)), _Deque_impl_data(std::move(__d))
542	{ }
543	#endif
544	};
545
546	_Tp_alloc_type&
547	_M_get_Tp_allocator() _GLIBCXX_NOEXCEPT
548	{ return this->_M_impl; }
549
550	const _Tp_alloc_type&
551	_M_get_Tp_allocator() const _GLIBCXX_NOEXCEPT
552	{ return this->_M_impl; }
553
554	_Map_alloc_type
555	_M_get_map_allocator() const _GLIBCXX_NOEXCEPT
556	{ return _Map_alloc_type(_M_get_Tp_allocator()); }
557
558	_Ptr
559	_M_allocate_node()
560	{
561	typedef __gnu_cxx::__alloc_traits<_Tp_alloc_type> _Traits;
562	return _Traits::allocate(_M_impl, __deque_buf_size(size: sizeof(_Tp)));
563	}
564
565	void
566	_M_deallocate_node(_Ptr __p) _GLIBCXX_NOEXCEPT
567	{
568	typedef __gnu_cxx::__alloc_traits<_Tp_alloc_type> _Traits;
569	_Traits::deallocate(_M_impl, __p, __deque_buf_size(size: sizeof(_Tp)));
570	}
571
572	_Map_pointer
573	_M_allocate_map(size_t __n)
574	{
575	_Map_alloc_type __map_alloc = _M_get_map_allocator();
576	return _Map_alloc_traits::allocate(__map_alloc, __n);
577	}
578
579	void
580	_M_deallocate_map(_Map_pointer __p, size_t __n) _GLIBCXX_NOEXCEPT
581	{
582	_Map_alloc_type __map_alloc = _M_get_map_allocator();
583	_Map_alloc_traits::deallocate(__map_alloc, __p, __n);
584	}
585
586	void _M_initialize_map(size_t);
587	void _M_create_nodes(_Map_pointer __nstart, _Map_pointer __nfinish);
588	void _M_destroy_nodes(_Map_pointer __nstart,
589	_Map_pointer __nfinish) _GLIBCXX_NOEXCEPT;
590	enum { _S_initial_map_size = `8` };
591
592	_Deque_impl _M_impl;
593	};
594
595	template<typename _Tp, typename _Alloc>
596	_Deque_base<_Tp, _Alloc>::
597	~_Deque_base() _GLIBCXX_NOEXCEPT
598	{
599	if (this->_M_impl._M_map)
600	{
601	_M_destroy_nodes(nstart: this->_M_impl._M_start._M_node,
602	nfinish: this->_M_impl._M_finish._M_node + `1`);
603	_M_deallocate_map(p: this->_M_impl._M_map, n: this->_M_impl._M_map_size);
604	}
605	}
606
607	/**
608	* @brief Layout storage.
609	* @param __num_elements The count of T's for which to allocate space
610	* at first.
611	* @return Nothing.
612	*
613	* The initial underlying memory layout is a bit complicated...
614	*/
615	template<typename _Tp, typename _Alloc>
616	void
617	_Deque_base<_Tp, _Alloc>::
618	_M_initialize_map(size_t __num_elements)
619	{
620	const size_t __num_nodes = (__num_elements / __deque_buf_size(size: sizeof(_Tp))
621	+ `1`);
622
623	this->_M_impl._M_map_size = std::max(a: (size_t) _S_initial_map_size,
624	b: size_t(__num_nodes + `2`));
625	this->_M_impl._M_map = _M_allocate_map(n: this->_M_impl._M_map_size);
626
627	// For "small" maps (needing less than _M_map_size nodes), allocation
628	// starts in the middle elements and grows outwards. So nstart may be
629	// the beginning of _M_map, but for small maps it may be as far in as
630	// _M_map+3.
631
632	_Map_pointer __nstart = (this->_M_impl._M_map
633	+ (this->_M_impl._M_map_size - __num_nodes) / `2`);
634	_Map_pointer __nfinish = __nstart + __num_nodes;
635
636	__try
637	{ _M_create_nodes(__nstart, __nfinish); }
638	__catch(...)
639	{
640	_M_deallocate_map(p: this->_M_impl._M_map, n: this->_M_impl._M_map_size);
641	this->_M_impl._M_map = _Map_pointer();
642	this->_M_impl._M_map_size = `0`;
643	__throw_exception_again;
644	}
645
646	this->_M_impl._M_start._M_set_node(__nstart);
647	this->_M_impl._M_finish._M_set_node(__nfinish - `1`);
648	this->_M_impl._M_start._M_cur = _M_impl._M_start._M_first;
649	this->_M_impl._M_finish._M_cur = (this->_M_impl._M_finish._M_first
650	+ __num_elements
651	% __deque_buf_size(size: sizeof(_Tp)));
652	}
653
654	template<typename _Tp, typename _Alloc>
655	void
656	_Deque_base<_Tp, _Alloc>::
657	_M_create_nodes(_Map_pointer __nstart, _Map_pointer __nfinish)
658	{
659	_Map_pointer __cur;
660	__try
661	{
662	for (__cur = __nstart; __cur < __nfinish; ++__cur)
663	__cur = this*->_M_allocate_node();
664	}
665	__catch(...)
666	{
667	_M_destroy_nodes(__nstart, nfinish: __cur);
668	__throw_exception_again;
669	}
670	}
671
672	template<typename _Tp, typename _Alloc>
673	void
674	_Deque_base<_Tp, _Alloc>::
675	_M_destroy_nodes(_Map_pointer __nstart,
676	_Map_pointer __nfinish) _GLIBCXX_NOEXCEPT
677	{
678	for (_Map_pointer __n = __nstart; __n < __nfinish; ++__n)
679	_M_deallocate_node(p: *__n);
680	}
681
682	/**
683	* @brief A standard container using fixed-size memory allocation and
684	* constant-time manipulation of elements at either end.
685	*
686	* @ingroup sequences
687	*
688	* @tparam _Tp Type of element.
689	* @tparam _Alloc Allocator type, defaults to allocator<_Tp>.
690	*
691	* Meets the requirements of a <a href="tables.html#65">container</a>, a
692	* <a href="tables.html#66">reversible container</a>, and a
693	* <a href="tables.html#67">sequence</a>, including the
694	* <a href="tables.html#68">optional sequence requirements</a>.
695	*
696	* In previous HP/SGI versions of deque, there was an extra template
697	* parameter so users could control the node size. This extension turned
698	* out to violate the C++ standard (it can be detected using template
699	* template parameters), and it was removed.
700	*
701	* Here's how a deque<Tp> manages memory. Each deque has 4 members:
702	*
703	* - Tp** _M_map
704	* - size_t _M_map_size
705	* - iterator _M_start, _M_finish
706	*
707	* map_size is at least 8. %map is an array of map_size
708	* pointers-to-@a nodes. (The name %map has nothing to do with the
709	* std::map class, and @b nodes should not be confused with
710	* std::list's usage of @a node.)
711	*
712	* A @a node has no specific type name as such, but it is referred
713	* to as @a node in this file. It is a simple array-of-Tp. If Tp
714	* is very large, there will be one Tp element per node (i.e., an
715	* @a array of one). For non-huge Tp's, node size is inversely
716	* related to Tp size: the larger the Tp, the fewer Tp's will fit
717	* in a node. The goal here is to keep the total size of a node
718	* relatively small and constant over different Tp's, to improve
719	* allocator efficiency.
720	*
721	* Not every pointer in the %map array will point to a node. If
722	* the initial number of elements in the deque is small, the
723	* /middle/ %map pointers will be valid, and the ones at the edges
724	* will be unused. This same situation will arise as the %map
725	* grows: available %map pointers, if any, will be on the ends. As
726	* new nodes are created, only a subset of the %map's pointers need
727	* to be copied @a outward.
728	*
729	* Class invariants:
730	* - For any nonsingular iterator i:
731	* - i.node points to a member of the %map array. (Yes, you read that
732	* correctly: i.node does not actually point to a node.) The member of
733	* the %map array is what actually points to the node.
734	* - i.first == *(i.node) (This points to the node (first Tp element).)
735	* - i.last == i.first + node_size
736	* - i.cur is a pointer in the range [i.first, i.last). NOTE:
737	* the implication of this is that i.cur is always a dereferenceable
738	* pointer, even if i is a past-the-end iterator.
739	* - Start and Finish are always nonsingular iterators. NOTE: this
740	* means that an empty deque must have one node, a deque with <N
741	* elements (where N is the node buffer size) must have one node, a
742	* deque with N through (2N-1) elements must have two nodes, etc.
743	* - For every node other than start.node and finish.node, every
744	* element in the node is an initialized object. If start.node ==
745	* finish.node, then [start.cur, finish.cur) are initialized
746	* objects, and the elements outside that range are uninitialized
747	* storage. Otherwise, [start.cur, start.last) and [finish.first,
748	* finish.cur) are initialized objects, and [start.first, start.cur)
749	* and [finish.cur, finish.last) are uninitialized storage.
750	* - [%map, %map + map_size) is a valid, non-empty range.
751	* - [start.node, finish.node] is a valid range contained within
752	* [%map, %map + map_size).
753	* - A pointer in the range [%map, %map + map_size) points to an allocated
754	* node if and only if the pointer is in the range
755	* [start.node, finish.node].
756	*
757	* Here's the magic: nothing in deque is @b aware of the discontiguous
758	* storage!
759	*
760	* The memory setup and layout occurs in the parent, _Base, and the iterator
761	* class is entirely responsible for @a leaping from one node to the next.
762	* All the implementation routines for deque itself work only through the
763	* start and finish iterators. This keeps the routines simple and sane,
764	* and we can use other standard algorithms as well.
765	*/
766	template<typename _Tp, typename _Alloc = std::allocator<_Tp> >
767	class deque : protected _Deque_base<_Tp, _Alloc>
768	{
769	#ifdef _GLIBCXX_CONCEPT_CHECKS
770	// concept requirements
771	typedef typename _Alloc::value_type _Alloc_value_type;
772	# if __cplusplus < 201103L
773	__glibcxx_class_requires(_Tp, _SGIAssignableConcept)
774	# endif
775	__glibcxx_class_requires2(_Tp, _Alloc_value_type, _SameTypeConcept)
776	#endif
777
778	#if __cplusplus >= 201103L
779	static_assert(is_same<typename remove_cv<_Tp>::type, _Tp>::value,
780	"std::deque must have a non-const, non-volatile value_type");
781	# if __cplusplus > 201703L \|\| defined __STRICT_ANSI__
782	static_assert(is_same<typename _Alloc::value_type, _Tp>::value,
783	"std::deque must have the same value_type as its allocator");
784	# endif
785	#endif
786
787	typedef _Deque_base<_Tp, _Alloc> _Base;
788	typedef typename _Base::_Tp_alloc_type _Tp_alloc_type;
789	typedef typename _Base::_Alloc_traits _Alloc_traits;
790	typedef typename _Base::_Map_pointer _Map_pointer;
791
792	public:
793	typedef _Tp value_type;
794	typedef typename _Alloc_traits::pointer pointer;
795	typedef typename _Alloc_traits::const_pointer const_pointer;
796	typedef typename _Alloc_traits::reference reference;
797	typedef typename _Alloc_traits::const_reference const_reference;
798	typedef typename _Base::iterator iterator;
799	typedef typename _Base::const_iterator const_iterator;
800	typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
801	typedef std::reverse_iterator<iterator> reverse_iterator;
802	typedef size_t size_type;
803	typedef ptrdiff_t difference_type;
804	typedef _Alloc allocator_type;
805
806	private:
807	static size_t _S_buffer_size() _GLIBCXX_NOEXCEPT
808	{ return __deque_buf_size(size: sizeof(_Tp)); }
809
810	// Functions controlling memory layout, and nothing else.
811	using _Base::_M_initialize_map;
812	using _Base::_M_create_nodes;
813	using _Base::_M_destroy_nodes;
814	using _Base::_M_allocate_node;
815	using _Base::_M_deallocate_node;
816	using _Base::_M_allocate_map;
817	using _Base::_M_deallocate_map;
818	using _Base::_M_get_Tp_allocator;
819
820	/**
821	* A total of four data members accumulated down the hierarchy.
822	* May be accessed via _M_impl.*
823	*/
824	using _Base::_M_impl;
825
826	public:
827	// [23.2.1.1] construct/copy/destroy
828	// (assign() and get_allocator() are also listed in this section)
829
830	/**
831	* @brief Creates a %deque with no elements.
832	*/
833	#if __cplusplus >= 201103L
834	deque() = default;
835	#else
836	deque() { }
837	#endif
838
839	/**
840	* @brief Creates a %deque with no elements.
841	* @param __a An allocator object.
842	*/
843	explicit
844	deque(const allocator_type& __a)
845	: _Base(__a, `0`) { }
846
847	#if __cplusplus >= 201103L
848	/**
849	* @brief Creates a %deque with default constructed elements.
850	* @param __n The number of elements to initially create.
851	* @param __a An allocator.
852	*
853	* This constructor fills the %deque with @a n default
854	* constructed elements.
855	*/
856	explicit
857	deque(size_type __n, const allocator_type& __a = allocator_type())
858	: _Base(__a, _S_check_init_len(__n, __a))
859	{ _M_default_initialize(); }
860
861	/**
862	* @brief Creates a %deque with copies of an exemplar element.
863	* @param __n The number of elements to initially create.
864	* @param __value An element to copy.
865	* @param __a An allocator.
866	*
867	* This constructor fills the %deque with @a __n copies of @a __value.
868	*/
869	deque(size_type __n, const value_type& __value,
870	const allocator_type& __a = allocator_type())
871	: _Base(__a, _S_check_init_len(__n, __a))
872	{ _M_fill_initialize(__value); }
873	#else
874	/**
875	* @brief Creates a %deque with copies of an exemplar element.
876	* @param __n The number of elements to initially create.
877	* @param __value An element to copy.
878	* @param __a An allocator.
879	*
880	* This constructor fills the %deque with @a __n copies of @a __value.
881	*/
882	explicit
883	deque(size_type __n, const value_type& __value = value_type(),
884	const allocator_type& __a = allocator_type())
885	: _Base(__a, _S_check_init_len(__n, __a))
886	{ _M_fill_initialize(__value); }
887	#endif
888
889	/**
890	* @brief %Deque copy constructor.
891	* @param __x A %deque of identical element and allocator types.
892	*
893	* The newly-created %deque uses a copy of the allocator object used
894	* by @a __x (unless the allocator traits dictate a different object).
895	*/
896	deque(const deque& __x)
897	: _Base(_Alloc_traits::_S_select_on_copy(__x._M_get_Tp_allocator()),
898	__x.size())
899	{ std::__uninitialized_copy_a(__x.begin(), __x.end(),
900	this->_M_impl._M_start,
901	_M_get_Tp_allocator()); }
902
903	#if __cplusplus >= 201103L
904	/**
905	* @brief %Deque move constructor.
906	*
907	* The newly-created %deque contains the exact contents of the
908	* moved instance.
909	* The contents of the moved instance are a valid, but unspecified
910	* %deque.
911	*/
912	deque(deque&&) = default;
913
914	/// Copy constructor with alternative allocator
915	deque(const deque& __x, const allocator_type& __a)
916	: _Base(__a, __x.size())
917	{ std::__uninitialized_copy_a(__x.begin(), __x.end(),
918	this->_M_impl._M_start,
919	_M_get_Tp_allocator()); }
920
921	/// Move constructor with alternative allocator
922	deque(deque&& __x, const allocator_type& __a)
923	: deque(std::move(__x), __a, typename _Alloc_traits::is_always_equal{})
924	{ }
925
926	private:
927	deque(deque&& __x, const allocator_type& __a, true_type)
928	: _Base(std::move(__x), __a)
929	{ }
930
931	deque(deque&& __x, const allocator_type& __a, false_type)
932	: _Base(std::move(__x), __a, __x.size())
933	{
934	if (__x.get_allocator() != __a && !__x.empty())
935	{
936	std::__uninitialized_move_a(__x.begin(), __x.end(),
937	this->_M_impl._M_start,
938	_M_get_Tp_allocator());
939	__x.clear();
940	}
941	}
942
943	public:
944	/**
945	* @brief Builds a %deque from an initializer list.
946	* @param __l An initializer_list.
947	* @param __a An allocator object.
948	*
949	* Create a %deque consisting of copies of the elements in the
950	* initializer_list @a __l.
951	*
952	* This will call the element type's copy constructor N times
953	* (where N is __l.size()) and do no memory reallocation.
954	*/
955	deque(initializer_list<value_type> __l,
956	const allocator_type& __a = allocator_type())
957	: _Base(__a)
958	{
959	_M_range_initialize(__l.begin(), __l.end(),
960	random_access_iterator_tag ());
961	}
962	#endif
963
964	/**
965	* @brief Builds a %deque from a range.
966	* @param __first An input iterator.
967	* @param __last An input iterator.
968	* @param __a An allocator object.
969	*
970	* Create a %deque consisting of copies of the elements from [__first,
971	* __last).
972	*
973	* If the iterators are forward, bidirectional, or random-access, then
974	* this will call the elements' copy constructor N times (where N is
975	* distance(__first,__last)) and do no memory reallocation. But if only
976	* input iterators are used, then this will do at most 2N calls to the
977	* copy constructor, and logN memory reallocations.
978	*/
979	#if __cplusplus >= 201103L
980	template<typename _InputIterator,
981	typename = std::_RequireInputIter<_InputIterator>>
982	deque(_InputIterator __first, _InputIterator __last,
983	const allocator_type& __a = allocator_type())
984	: _Base(__a)
985	{
986	_M_range_initialize(__first, __last,
987	std::__iterator_category(__first));
988	}
989	#else
990	template<typename _InputIterator>
991	deque(_InputIterator __first, _InputIterator __last,
992	const allocator_type& __a = allocator_type())
993	: _Base(__a)
994	{
995	// Check whether it's an integral type. If so, it's not an iterator.
996	typedef typename std::__is_integer<_InputIterator>::__type _Integral;
997	_M_initialize_dispatch(__first, __last, _Integral());
998	}
999	#endif
1000
1001	/**
1002	* The dtor only erases the elements, and note that if the elements
1003	* themselves are pointers, the pointed-to memory is not touched in any
1004	* way. Managing the pointer is the user's responsibility.
1005	*/
1006	~deque()
1007	{ _M_destroy_data(begin(), end(), _M_get_Tp_allocator()); }
1008
1009	/**
1010	* @brief %Deque assignment operator.
1011	* @param __x A %deque of identical element and allocator types.
1012	*
1013	* All the elements of @a x are copied.
1014	*
1015	* The newly-created %deque uses a copy of the allocator object used
1016	* by @a __x (unless the allocator traits dictate a different object).
1017	*/
1018	deque&
1019	operator=(const deque& __x);
1020
1021	#if __cplusplus >= 201103L
1022	/**
1023	* @brief %Deque move assignment operator.
1024	* @param __x A %deque of identical element and allocator types.
1025	*
1026	* The contents of @a __x are moved into this deque (without copying,
1027	* if the allocators permit it).
1028	* @a __x is a valid, but unspecified %deque.
1029	*/
1030	deque&
1031	operator=(deque&& __x) noexcept(_Alloc_traits::_S_always_equal())
1032	{
1033	using __always_equal = typename _Alloc_traits::is_always_equal;
1034	_M_move_assign1(std::move(__x), __always_equal{});
1035	return *this;
1036	}
1037
1038	/**
1039	* @brief Assigns an initializer list to a %deque.
1040	* @param __l An initializer_list.
1041	*
1042	* This function fills a %deque with copies of the elements in the
1043	* initializer_list @a __l.
1044	*
1045	* Note that the assignment completely changes the %deque and that the
1046	* resulting %deque's size is the same as the number of elements
1047	* assigned.
1048	*/
1049	deque&
1050	operator=(initializer_list<value_type> __l)
1051	{
1052	_M_assign_aux(__l.begin(), __l.end(),
1053	random_access_iterator_tag ());
1054	return *this;
1055	}
1056	#endif
1057
1058	/**
1059	* @brief Assigns a given value to a %deque.
1060	* @param __n Number of elements to be assigned.
1061	* @param __val Value to be assigned.
1062	*
1063	* This function fills a %deque with @a n copies of the given
1064	* value. Note that the assignment completely changes the
1065	* %deque and that the resulting %deque's size is the same as
1066	* the number of elements assigned.
1067	*/
1068	void
1069	assign(size_type __n, const value_type& __val)
1070	{ _M_fill_assign(__n, __val); }
1071
1072	/**
1073	* @brief Assigns a range to a %deque.
1074	* @param __first An input iterator.
1075	* @param __last An input iterator.
1076	*
1077	* This function fills a %deque with copies of the elements in the
1078	* range [__first,__last).
1079	*
1080	* Note that the assignment completely changes the %deque and that the
1081	* resulting %deque's size is the same as the number of elements
1082	* assigned.
1083	*/
1084	#if __cplusplus >= 201103L
1085	template<typename _InputIterator,
1086	typename = std::_RequireInputIter<_InputIterator>>
1087	void
1088	assign(_InputIterator __first, _InputIterator __last)
1089	{ _M_assign_aux(__first, __last, std::__iterator_category(__first)); }
1090	#else
1091	template<typename _InputIterator>
1092	void
1093	assign(_InputIterator __first, _InputIterator __last)
1094	{
1095	typedef typename std::__is_integer<_InputIterator>::__type _Integral;
1096	_M_assign_dispatch(__first, __last, _Integral());
1097	}
1098	#endif
1099
1100	#if __cplusplus >= 201103L
1101	/**
1102	* @brief Assigns an initializer list to a %deque.
1103	* @param __l An initializer_list.
1104	*
1105	* This function fills a %deque with copies of the elements in the
1106	* initializer_list @a __l.
1107	*
1108	* Note that the assignment completely changes the %deque and that the
1109	* resulting %deque's size is the same as the number of elements
1110	* assigned.
1111	*/
1112	void
1113	assign(initializer_list<value_type> __l)
1114	{ _M_assign_aux(__l.begin(), __l.end(), random_access_iterator_tag ()); }
1115	#endif
1116
1117	/// Get a copy of the memory allocation object.
1118	allocator_type
1119	get_allocator() const _GLIBCXX_NOEXCEPT
1120	{ return _Base::get_allocator(); }
1121
1122	// iterators
1123	/**
1124	* Returns a read/write iterator that points to the first element in the
1125	* %deque. Iteration is done in ordinary element order.
1126	*/
1127	iterator
1128	begin() _GLIBCXX_NOEXCEPT
1129	{ return this->_M_impl._M_start; }
1130
1131	/**
1132	* Returns a read-only (constant) iterator that points to the first
1133	* element in the %deque. Iteration is done in ordinary element order.
1134	*/
1135	const_iterator
1136	begin() const _GLIBCXX_NOEXCEPT
1137	{ return this->_M_impl._M_start; }
1138
1139	/**
1140	* Returns a read/write iterator that points one past the last
1141	* element in the %deque. Iteration is done in ordinary
1142	* element order.
1143	*/
1144	iterator
1145	end() _GLIBCXX_NOEXCEPT
1146	{ return this->_M_impl._M_finish; }
1147
1148	/**
1149	* Returns a read-only (constant) iterator that points one past
1150	* the last element in the %deque. Iteration is done in
1151	* ordinary element order.
1152	*/
1153	const_iterator
1154	end() const _GLIBCXX_NOEXCEPT
1155	{ return this->_M_impl._M_finish; }
1156
1157	/**
1158	* Returns a read/write reverse iterator that points to the
1159	* last element in the %deque. Iteration is done in reverse
1160	* element order.
1161	*/
1162	reverse_iterator
1163	rbegin() _GLIBCXX_NOEXCEPT
1164	{ return reverse_iterator(this->_M_impl._M_finish); }
1165
1166	/**
1167	* Returns a read-only (constant) reverse iterator that points
1168	* to the last element in the %deque. Iteration is done in
1169	* reverse element order.
1170	*/
1171	const_reverse_iterator
1172	rbegin() const _GLIBCXX_NOEXCEPT
1173	{ return const_reverse_iterator(this->_M_impl._M_finish); }
1174
1175	/**
1176	* Returns a read/write reverse iterator that points to one
1177	* before the first element in the %deque. Iteration is done
1178	* in reverse element order.
1179	*/
1180	reverse_iterator
1181	rend() _GLIBCXX_NOEXCEPT
1182	{ return reverse_iterator(this->_M_impl._M_start); }
1183
1184	/**
1185	* Returns a read-only (constant) reverse iterator that points
1186	* to one before the first element in the %deque. Iteration is
1187	* done in reverse element order.
1188	*/
1189	const_reverse_iterator
1190	rend() const _GLIBCXX_NOEXCEPT
1191	{ return const_reverse_iterator(this->_M_impl._M_start); }
1192
1193	#if __cplusplus >= 201103L
1194	/**
1195	* Returns a read-only (constant) iterator that points to the first
1196	* element in the %deque. Iteration is done in ordinary element order.
1197	*/
1198	const_iterator
1199	cbegin() const noexcept
1200	{ return this->_M_impl._M_start; }
1201
1202	/**
1203	* Returns a read-only (constant) iterator that points one past
1204	* the last element in the %deque. Iteration is done in
1205	* ordinary element order.
1206	*/
1207	const_iterator
1208	cend() const noexcept
1209	{ return this->_M_impl._M_finish; }
1210
1211	/**
1212	* Returns a read-only (constant) reverse iterator that points
1213	* to the last element in the %deque. Iteration is done in
1214	* reverse element order.
1215	*/
1216	const_reverse_iterator
1217	crbegin() const noexcept
1218	{ return const_reverse_iterator(this->_M_impl._M_finish); }
1219
1220	/**
1221	* Returns a read-only (constant) reverse iterator that points
1222	* to one before the first element in the %deque. Iteration is
1223	* done in reverse element order.
1224	*/
1225	const_reverse_iterator
1226	crend() const noexcept
1227	{ return const_reverse_iterator(this->_M_impl._M_start); }
1228	#endif
1229
1230	// [23.2.1.2] capacity
1231	/* Returns the number of elements in the %deque. /
1232	size_type
1233	size() const _GLIBCXX_NOEXCEPT
1234	{ return this->_M_impl._M_finish - this->_M_impl._M_start; }
1235
1236	/* Returns the size() of the largest possible %deque. /
1237	size_type
1238	max_size() const _GLIBCXX_NOEXCEPT
1239	{ return _S_max_size(a: _M_get_Tp_allocator()); }
1240
1241	#if __cplusplus >= 201103L
1242	/**
1243	* @brief Resizes the %deque to the specified number of elements.
1244	* @param __new_size Number of elements the %deque should contain.
1245	*
1246	* This function will %resize the %deque to the specified
1247	* number of elements. If the number is smaller than the
1248	* %deque's current size the %deque is truncated, otherwise
1249	* default constructed elements are appended.
1250	*/
1251	void
1252	resize(size_type __new_size)
1253	{
1254	const size_type __len = size();
1255	if (__new_size > __len)
1256	_M_default_append(n: __new_size - __len);
1257	else if (__new_size < __len)
1258	_M_erase_at_end(pos: this->_M_impl._M_start
1259	+ difference_type(__new_size));
1260	}
1261
1262	/**
1263	* @brief Resizes the %deque to the specified number of elements.
1264	* @param __new_size Number of elements the %deque should contain.
1265	* @param __x Data with which new elements should be populated.
1266	*
1267	* This function will %resize the %deque to the specified
1268	* number of elements. If the number is smaller than the
1269	* %deque's current size the %deque is truncated, otherwise the
1270	* %deque is extended and new elements are populated with given
1271	* data.
1272	*/
1273	void
1274	resize(size_type __new_size, const value_type& __x)
1275	#else
1276	/**
1277	* @brief Resizes the %deque to the specified number of elements.
1278	* @param __new_size Number of elements the %deque should contain.
1279	* @param __x Data with which new elements should be populated.
1280	*
1281	* This function will %resize the %deque to the specified
1282	* number of elements. If the number is smaller than the
1283	* %deque's current size the %deque is truncated, otherwise the
1284	* %deque is extended and new elements are populated with given
1285	* data.
1286	*/
1287	void
1288	resize(size_type __new_size, value_type __x = value_type())
1289	#endif
1290	{
1291	const size_type __len = size();
1292	if (__new_size > __len)
1293	_M_fill_insert(pos: this->_M_impl._M_finish, n: __new_size - __len, __x);
1294	else if (__new_size < __len)
1295	_M_erase_at_end(pos: this->_M_impl._M_start
1296	+ difference_type(__new_size));
1297	}
1298
1299	#if __cplusplus >= 201103L
1300	/* A non-binding request to reduce memory use. /
1301	void
1302	shrink_to_fit() noexcept
1303	{ _M_shrink_to_fit(); }
1304	#endif
1305
1306	/**
1307	* Returns true if the %deque is empty. (Thus begin() would
1308	* equal end().)
1309	*/
1310	_GLIBCXX_NODISCARD bool
1311	empty() const _GLIBCXX_NOEXCEPT
1312	{ return this->_M_impl._M_finish == this->_M_impl._M_start; }
1313
1314	// element access
1315	/**
1316	* @brief Subscript access to the data contained in the %deque.
1317	* @param __n The index of the element for which data should be
1318	* accessed.
1319	* @return Read/write reference to data.
1320	*
1321	* This operator allows for easy, array-style, data access.
1322	* Note that data access with this operator is unchecked and
1323	* out_of_range lookups are not defined. (For checked lookups
1324	* see at().)
1325	*/
1326	reference
1327	operator[](size_type __n) _GLIBCXX_NOEXCEPT
1328	{
1329	__glibcxx_requires_subscript(__n);
1330	return this->_M_impl._M_start[difference_type(__n)];
1331	}
1332
1333	/**
1334	* @brief Subscript access to the data contained in the %deque.
1335	* @param __n The index of the element for which data should be
1336	* accessed.
1337	* @return Read-only (constant) reference to data.
1338	*
1339	* This operator allows for easy, array-style, data access.
1340	* Note that data access with this operator is unchecked and
1341	* out_of_range lookups are not defined. (For checked lookups
1342	* see at().)
1343	*/
1344	const_reference
1345	operator[](size_type __n) const _GLIBCXX_NOEXCEPT
1346	{
1347	__glibcxx_requires_subscript(__n);
1348	return this->_M_impl._M_start[difference_type(__n)];
1349	}
1350
1351	protected:
1352	/// Safety check used only from at().
1353	void
1354	_M_range_check(size_type __n) const
1355	{
1356	if (__n >= this->size())
1357	__throw_out_of_range_fmt(__N("deque::_M_range_check: __n "
1358	"(which is %zu)>= this->size() "
1359	"(which is %zu)"),
1360	__n, this->size());
1361	}
1362
1363	public:
1364	/**
1365	* @brief Provides access to the data contained in the %deque.
1366	* @param __n The index of the element for which data should be
1367	* accessed.
1368	* @return Read/write reference to data.
1369	* @throw std::out_of_range If @a __n is an invalid index.
1370	*
1371	* This function provides for safer data access. The parameter
1372	* is first checked that it is in the range of the deque. The
1373	* function throws out_of_range if the check fails.
1374	*/
1375	reference
1376	at(size_type __n)
1377	{
1378	_M_range_check(__n);
1379	return (*this)[__n];
1380	}
1381
1382	/**
1383	* @brief Provides access to the data contained in the %deque.
1384	* @param __n The index of the element for which data should be
1385	* accessed.
1386	* @return Read-only (constant) reference to data.
1387	* @throw std::out_of_range If @a __n is an invalid index.
1388	*
1389	* This function provides for safer data access. The parameter is first
1390	* checked that it is in the range of the deque. The function throws
1391	* out_of_range if the check fails.
1392	*/
1393	const_reference
1394	at(size_type __n) const
1395	{
1396	_M_range_check(__n);
1397	return (*this)[__n];
1398	}
1399
1400	/**
1401	* Returns a read/write reference to the data at the first
1402	* element of the %deque.
1403	*/
1404	reference
1405	front() _GLIBCXX_NOEXCEPT
1406	{
1407	__glibcxx_requires_nonempty();
1408	return *begin();
1409	}
1410
1411	/**
1412	* Returns a read-only (constant) reference to the data at the first
1413	* element of the %deque.
1414	*/
1415	const_reference
1416	front() const _GLIBCXX_NOEXCEPT
1417	{
1418	__glibcxx_requires_nonempty();
1419	return *begin();
1420	}
1421
1422	/**
1423	* Returns a read/write reference to the data at the last element of the
1424	* %deque.
1425	*/
1426	reference
1427	back() _GLIBCXX_NOEXCEPT
1428	{
1429	__glibcxx_requires_nonempty();
1430	iterator __tmp = end();
1431	--__tmp;
1432	return *__tmp;
1433	}
1434
1435	/**
1436	* Returns a read-only (constant) reference to the data at the last
1437	* element of the %deque.
1438	*/
1439	const_reference
1440	back() const _GLIBCXX_NOEXCEPT
1441	{
1442	__glibcxx_requires_nonempty();
1443	const_iterator __tmp = end();
1444	--__tmp;
1445	return *__tmp;
1446	}
1447
1448	// [23.2.1.2] modifiers
1449	/**
1450	* @brief Add data to the front of the %deque.
1451	* @param __x Data to be added.
1452	*
1453	* This is a typical stack operation. The function creates an
1454	* element at the front of the %deque and assigns the given
1455	* data to it. Due to the nature of a %deque this operation
1456	* can be done in constant time.
1457	*/
1458	void
1459	push_front(const value_type& __x)
1460	{
1461	if (this->_M_impl._M_start._M_cur != this->_M_impl._M_start._M_first)
1462	{
1463	_Alloc_traits::construct(this->_M_impl,
1464	this->_M_impl._M_start._M_cur - `1`,
1465	__x);
1466	--this->_M_impl._M_start._M_cur;
1467	}
1468	else
1469	_M_push_front_aux(__x);
1470	}
1471
1472	#if __cplusplus >= 201103L
1473	void
1474	push_front(value_type&& __x)
1475	{ emplace_front(std::move(__x)); }
1476
1477	template<typename... _Args>
1478	#if __cplusplus > 201402L
1479	reference
1480	#else
1481	void
1482	#endif
1483	emplace_front(_Args&&... __args);
1484	#endif
1485
1486	/**
1487	* @brief Add data to the end of the %deque.
1488	* @param __x Data to be added.
1489	*
1490	* This is a typical stack operation. The function creates an
1491	* element at the end of the %deque and assigns the given data
1492	* to it. Due to the nature of a %deque this operation can be
1493	* done in constant time.
1494	*/
1495	void
1496	push_back(const value_type& __x)
1497	{
1498	if (this->_M_impl._M_finish._M_cur
1499	!= this->_M_impl._M_finish._M_last - `1`)
1500	{
1501	_Alloc_traits::construct(this->_M_impl,
1502	this->_M_impl._M_finish._M_cur, __x);
1503	++this->_M_impl._M_finish._M_cur;
1504	}
1505	else
1506	_M_push_back_aux(__x);
1507	}
1508
1509	#if __cplusplus >= 201103L
1510	void
1511	push_back(value_type&& __x)
1512	{ emplace_back(std::move(__x)); }
1513
1514	template<typename... _Args>
1515	#if __cplusplus > 201402L
1516	reference
1517	#else
1518	void
1519	#endif
1520	emplace_back(_Args&&... __args);
1521	#endif
1522
1523	/**
1524	* @brief Removes first element.
1525	*
1526	* This is a typical stack operation. It shrinks the %deque by one.
1527	*
1528	* Note that no data is returned, and if the first element's data is
1529	* needed, it should be retrieved before pop_front() is called.
1530	*/
1531	void
1532	pop_front() _GLIBCXX_NOEXCEPT
1533	{
1534	__glibcxx_requires_nonempty();
1535	if (this->_M_impl._M_start._M_cur
1536	!= this->_M_impl._M_start._M_last - `1`)
1537	{
1538	_Alloc_traits::destroy(_M_get_Tp_allocator(),
1539	this->_M_impl._M_start._M_cur);
1540	++this->_M_impl._M_start._M_cur;
1541	}
1542	else
1543	_M_pop_front_aux();
1544	}
1545
1546	/**
1547	* @brief Removes last element.
1548	*
1549	* This is a typical stack operation. It shrinks the %deque by one.
1550	*
1551	* Note that no data is returned, and if the last element's data is
1552	* needed, it should be retrieved before pop_back() is called.
1553	*/
1554	void
1555	pop_back() _GLIBCXX_NOEXCEPT
1556	{
1557	__glibcxx_requires_nonempty();
1558	if (this->_M_impl._M_finish._M_cur
1559	!= this->_M_impl._M_finish._M_first)
1560	{
1561	--this->_M_impl._M_finish._M_cur;
1562	_Alloc_traits::destroy(_M_get_Tp_allocator(),
1563	this->_M_impl._M_finish._M_cur);
1564	}
1565	else
1566	_M_pop_back_aux();
1567	}
1568
1569	#if __cplusplus >= 201103L
1570	/**
1571	* @brief Inserts an object in %deque before specified iterator.
1572	* @param __position A const_iterator into the %deque.
1573	* @param __args Arguments.
1574	* @return An iterator that points to the inserted data.
1575	*
1576	* This function will insert an object of type T constructed
1577	* with T(std::forward<Args>(args)...) before the specified location.
1578	*/
1579	template<typename... _Args>
1580	iterator
1581	emplace(const_iterator __position, _Args&&... __args);
1582
1583	/**
1584	* @brief Inserts given value into %deque before specified iterator.
1585	* @param __position A const_iterator into the %deque.
1586	* @param __x Data to be inserted.
1587	* @return An iterator that points to the inserted data.
1588	*
1589	* This function will insert a copy of the given value before the
1590	* specified location.
1591	*/
1592	iterator
1593	insert(const_iterator __position, const value_type& __x);
1594	#else
1595	/**
1596	* @brief Inserts given value into %deque before specified iterator.
1597	* @param __position An iterator into the %deque.
1598	* @param __x Data to be inserted.
1599	* @return An iterator that points to the inserted data.
1600	*
1601	* This function will insert a copy of the given value before the
1602	* specified location.
1603	*/
1604	iterator
1605	insert(iterator __position, const value_type& __x);
1606	#endif
1607
1608	#if __cplusplus >= 201103L
1609	/**
1610	* @brief Inserts given rvalue into %deque before specified iterator.
1611	* @param __position A const_iterator into the %deque.
1612	* @param __x Data to be inserted.
1613	* @return An iterator that points to the inserted data.
1614	*
1615	* This function will insert a copy of the given rvalue before the
1616	* specified location.
1617	*/
1618	iterator
1619	insert(const_iterator __position, value_type&& __x)
1620	{ return emplace(__position, std::move(__x)); }
1621
1622	/**
1623	* @brief Inserts an initializer list into the %deque.
1624	* @param __p An iterator into the %deque.
1625	* @param __l An initializer_list.
1626	* @return An iterator that points to the inserted data.
1627	*
1628	* This function will insert copies of the data in the
1629	* initializer_list @a __l into the %deque before the location
1630	* specified by @a __p. This is known as <em>list insert</em>.
1631	*/
1632	iterator
1633	insert(const_iterator __p, initializer_list<value_type> __l)
1634	{
1635	auto __offset = __p - cbegin();
1636	_M_range_insert_aux(__p._M_const_cast(), __l.begin(), __l.end(),
1637	std::random_access_iterator_tag ());
1638	return begin() + __offset;
1639	}
1640
1641	/**
1642	* @brief Inserts a number of copies of given data into the %deque.
1643	* @param __position A const_iterator into the %deque.
1644	* @param __n Number of elements to be inserted.
1645	* @param __x Data to be inserted.
1646	* @return An iterator that points to the inserted data.
1647	*
1648	* This function will insert a specified number of copies of the given
1649	* data before the location specified by @a __position.
1650	*/
1651	iterator
1652	insert(const_iterator __position, size_type __n, const value_type& __x)
1653	{
1654	difference_type __offset = __position - cbegin();
1655	_M_fill_insert(pos: __position._M_const_cast(), __n, __x);
1656	return begin() + __offset;
1657	}
1658	#else
1659	/**
1660	* @brief Inserts a number of copies of given data into the %deque.
1661	* @param __position An iterator into the %deque.
1662	* @param __n Number of elements to be inserted.
1663	* @param __x Data to be inserted.
1664	*
1665	* This function will insert a specified number of copies of the given
1666	* data before the location specified by @a __position.
1667	*/
1668	void
1669	insert(iterator __position, size_type __n, const value_type& __x)
1670	{ _M_fill_insert(__position, __n, __x); }
1671	#endif
1672
1673	#if __cplusplus >= 201103L
1674	/**
1675	* @brief Inserts a range into the %deque.
1676	* @param __position A const_iterator into the %deque.
1677	* @param __first An input iterator.
1678	* @param __last An input iterator.
1679	* @return An iterator that points to the inserted data.
1680	*
1681	* This function will insert copies of the data in the range
1682	* [__first,__last) into the %deque before the location specified
1683	* by @a __position. This is known as <em>range insert</em>.
1684	*/
1685	template<typename _InputIterator,
1686	typename = std::_RequireInputIter<_InputIterator>>
1687	iterator
1688	insert(const_iterator __position, _InputIterator __first,
1689	_InputIterator __last)
1690	{
1691	difference_type __offset = __position - cbegin();
1692	_M_range_insert_aux(__position._M_const_cast(), __first, __last,
1693	std::__iterator_category(__first));
1694	return begin() + __offset;
1695	}
1696	#else
1697	/**
1698	* @brief Inserts a range into the %deque.
1699	* @param __position An iterator into the %deque.
1700	* @param __first An input iterator.
1701	* @param __last An input iterator.
1702	*
1703	* This function will insert copies of the data in the range
1704	* [__first,__last) into the %deque before the location specified
1705	* by @a __position. This is known as <em>range insert</em>.
1706	*/
1707	template<typename _InputIterator>
1708	void
1709	insert(iterator __position, _InputIterator __first,
1710	_InputIterator __last)
1711	{
1712	// Check whether it's an integral type. If so, it's not an iterator.
1713	typedef typename std::__is_integer<_InputIterator>::__type _Integral;
1714	_M_insert_dispatch(__position, __first, __last, _Integral());
1715	}
1716	#endif
1717
1718	/**
1719	* @brief Remove element at given position.
1720	* @param __position Iterator pointing to element to be erased.
1721	* @return An iterator pointing to the next element (or end()).
1722	*
1723	* This function will erase the element at the given position and thus
1724	* shorten the %deque by one.
1725	*
1726	* The user is cautioned that
1727	* this function only erases the element, and that if the element is
1728	* itself a pointer, the pointed-to memory is not touched in any way.
1729	* Managing the pointer is the user's responsibility.
1730	*/
1731	iterator
1732	#if __cplusplus >= 201103L
1733	erase(const_iterator __position)
1734	#else
1735	erase(iterator __position)
1736	#endif
1737	{ return _M_erase(__position._M_const_cast()); }
1738
1739	/**
1740	* @brief Remove a range of elements.
1741	* @param __first Iterator pointing to the first element to be erased.
1742	* @param __last Iterator pointing to one past the last element to be
1743	* erased.
1744	* @return An iterator pointing to the element pointed to by @a last
1745	* prior to erasing (or end()).
1746	*
1747	* This function will erase the elements in the range
1748	* [__first,__last) and shorten the %deque accordingly.
1749	*
1750	* The user is cautioned that
1751	* this function only erases the elements, and that if the elements
1752	* themselves are pointers, the pointed-to memory is not touched in any
1753	* way. Managing the pointer is the user's responsibility.
1754	*/
1755	iterator
1756	#if __cplusplus >= 201103L
1757	erase(const_iterator __first, const_iterator __last)
1758	#else
1759	erase(iterator __first, iterator __last)
1760	#endif
1761	{ return _M_erase(__first._M_const_cast(), __last._M_const_cast()); }
1762
1763	/**
1764	* @brief Swaps data with another %deque.
1765	* @param __x A %deque of the same element and allocator types.
1766	*
1767	* This exchanges the elements between two deques in constant time.
1768	* (Four pointers, so it should be quite fast.)
1769	* Note that the global std::swap() function is specialized such that
1770	* std::swap(d1,d2) will feed to this function.
1771	*
1772	* Whether the allocators are swapped depends on the allocator traits.
1773	*/
1774	void
1775	swap(deque& __x) _GLIBCXX_NOEXCEPT
1776	{
1777	#if __cplusplus >= 201103L
1778	__glibcxx_assert(_Alloc_traits::propagate_on_container_swap::value
1779	\|\| _M_get_Tp_allocator() == __x._M_get_Tp_allocator());
1780	#endif
1781	_M_impl._M_swap_data(__x._M_impl);
1782	_Alloc_traits::_S_on_swap(_M_get_Tp_allocator(),
1783	__x._M_get_Tp_allocator());
1784	}
1785
1786	/**
1787	* Erases all the elements. Note that this function only erases the
1788	* elements, and that if the elements themselves are pointers, the
1789	* pointed-to memory is not touched in any way. Managing the pointer is
1790	* the user's responsibility.
1791	*/
1792	void
1793	clear() _GLIBCXX_NOEXCEPT
1794	{ _M_erase_at_end(pos: begin()); }
1795
1796	protected:
1797	// Internal constructor functions follow.
1798
1799	#if __cplusplus < 201103L
1800	// called by the range constructor to implement [23.1.1]/9
1801
1802	// _GLIBCXX_RESOLVE_LIB_DEFECTS
1803	// 438. Ambiguity in the "do the right thing" clause
1804	template<typename _Integer>
1805	void
1806	_M_initialize_dispatch(_Integer __n, _Integer __x, __true_type)
1807	{
1808	_M_initialize_map(_S_check_init_len(static_cast<size_type>(__n),
1809	_M_get_Tp_allocator()));
1810	_M_fill_initialize(__x);
1811	}
1812
1813	// called by the range constructor to implement [23.1.1]/9
1814	template<typename _InputIterator>
1815	void
1816	_M_initialize_dispatch(_InputIterator __first, _InputIterator __last,
1817	__false_type)
1818	{
1819	_M_range_initialize(__first, __last,
1820	std::__iterator_category(__first));
1821	}
1822	#endif
1823
1824	static size_t
1825	_S_check_init_len(size_t __n, const allocator_type& __a)
1826	{
1827	if (__n > _S_max_size(__a))
1828	__throw_length_error(
1829	__N("cannot create std::deque larger than max_size()"));
1830	return __n;
1831	}
1832
1833	static size_type
1834	_S_max_size(const _Tp_alloc_type& __a) _GLIBCXX_NOEXCEPT
1835	{
1836	const size_t __diffmax = __gnu_cxx::__numeric_traits<ptrdiff_t>::__max;
1837	const size_t __allocmax = _Alloc_traits::max_size(__a);
1838	return (std::min)(a: __diffmax, b: __allocmax);
1839	}
1840
1841	// called by the second initialize_dispatch above
1842	///@{
1843	/**
1844	* @brief Fills the deque with whatever is in [first,last).
1845	* @param __first An input iterator.
1846	* @param __last An input iterator.
1847	* @return Nothing.
1848	*
1849	* If the iterators are actually forward iterators (or better), then the
1850	* memory layout can be done all at once. Else we move forward using
1851	* push_back on each value from the iterator.
1852	*/
1853	template<typename _InputIterator>
1854	void
1855	_M_range_initialize(_InputIterator __first, _InputIterator __last,
1856	std::input_iterator_tag);
1857
1858	// called by the second initialize_dispatch above
1859	template<typename _ForwardIterator>
1860	void
1861	_M_range_initialize(_ForwardIterator __first, _ForwardIterator __last,
1862	std::forward_iterator_tag);
1863	///@}
1864
1865	/**
1866	* @brief Fills the %deque with copies of value.
1867	* @param __value Initial value.
1868	* @return Nothing.
1869	* @pre _M_start and _M_finish have already been initialized,
1870	* but none of the %deque's elements have yet been constructed.
1871	*
1872	* This function is called only when the user provides an explicit size
1873	* (with or without an explicit exemplar value).
1874	*/
1875	void
1876	_M_fill_initialize(const value_type& __value);
1877
1878	#if __cplusplus >= 201103L
1879	// called by deque(n).
1880	void
1881	_M_default_initialize();
1882	#endif
1883
1884	// Internal assign functions follow. The _aux functions do the actual*
1885	// assignment work for the range versions.
1886
1887	#if __cplusplus < 201103L
1888	// called by the range assign to implement [23.1.1]/9
1889
1890	// _GLIBCXX_RESOLVE_LIB_DEFECTS
1891	// 438. Ambiguity in the "do the right thing" clause
1892	template<typename _Integer>
1893	void
1894	_M_assign_dispatch(_Integer __n, _Integer __val, __true_type)
1895	{ _M_fill_assign(__n, __val); }
1896
1897	// called by the range assign to implement [23.1.1]/9
1898	template<typename _InputIterator>
1899	void
1900	_M_assign_dispatch(_InputIterator __first, _InputIterator __last,
1901	__false_type)
1902	{ _M_assign_aux(__first, __last, std::__iterator_category(__first)); }
1903	#endif
1904
1905	// called by the second assign_dispatch above
1906	template<typename _InputIterator>
1907	void
1908	_M_assign_aux(_InputIterator __first, _InputIterator __last,
1909	std::input_iterator_tag);
1910
1911	// called by the second assign_dispatch above
1912	template<typename _ForwardIterator>
1913	void
1914	_M_assign_aux(_ForwardIterator __first, _ForwardIterator __last,
1915	std::forward_iterator_tag)
1916	{
1917	const size_type __len = std::distance(__first, __last);
1918	if (__len > size())
1919	{
1920	_ForwardIterator __mid = __first;
1921	std::advance(__mid, size());
1922	std::copy(__first, __mid, begin());
1923	_M_range_insert_aux(end(), __mid, __last,
1924	std::__iterator_category(__first));
1925	}
1926	else
1927	_M_erase_at_end(pos: std::copy(__first, __last, begin()));
1928	}
1929
1930	// Called by assign(n,t), and the range assign when it turns out
1931	// to be the same thing.
1932	void
1933	_M_fill_assign(size_type __n, const value_type& __val)
1934	{
1935	if (__n > size())
1936	{
1937	std::fill(begin(), end(), __val);
1938	_M_fill_insert(pos: end(), n: __n - size(), x: __val);
1939	}
1940	else
1941	{
1942	_M_erase_at_end(pos: begin() + difference_type(__n));
1943	std::fill(begin(), end(), __val);
1944	}
1945	}
1946
1947	///@{
1948	/// Helper functions for push_ and pop_.
1949	#if __cplusplus < 201103L
1950	void _M_push_back_aux(const value_type&);
1951
1952	void _M_push_front_aux(const value_type&);
1953	#else
1954	template<typename... _Args>
1955	void _M_push_back_aux(_Args&&... __args);
1956
1957	template<typename... _Args>
1958	void _M_push_front_aux(_Args&&... __args);
1959	#endif
1960
1961	void _M_pop_back_aux();
1962
1963	void _M_pop_front_aux();
1964	///@}
1965
1966	// Internal insert functions follow. The _aux functions do the actual*
1967	// insertion work when all shortcuts fail.
1968
1969	#if __cplusplus < 201103L
1970	// called by the range insert to implement [23.1.1]/9
1971
1972	// _GLIBCXX_RESOLVE_LIB_DEFECTS
1973	// 438. Ambiguity in the "do the right thing" clause
1974	template<typename _Integer>
1975	void
1976	_M_insert_dispatch(iterator __pos,
1977	_Integer __n, _Integer __x, __true_type)
1978	{ _M_fill_insert(__pos, __n, __x); }
1979
1980	// called by the range insert to implement [23.1.1]/9
1981	template<typename _InputIterator>
1982	void
1983	_M_insert_dispatch(iterator __pos,
1984	_InputIterator __first, _InputIterator __last,
1985	__false_type)
1986	{
1987	_M_range_insert_aux(__pos, __first, __last,
1988	std::__iterator_category(__first));
1989	}
1990	#endif
1991
1992	// called by the second insert_dispatch above
1993	template<typename _InputIterator>
1994	void
1995	_M_range_insert_aux(iterator __pos, _InputIterator __first,
1996	_InputIterator __last, std::input_iterator_tag);
1997
1998	// called by the second insert_dispatch above
1999	template<typename _ForwardIterator>
2000	void
2001	_M_range_insert_aux(iterator __pos, _ForwardIterator __first,
2002	_ForwardIterator __last, std::forward_iterator_tag);
2003
2004	// Called by insert(p,n,x), and the range insert when it turns out to be
2005	// the same thing. Can use fill functions in optimal situations,
2006	// otherwise passes off to insert_aux(p,n,x).
2007	void
2008	_M_fill_insert(iterator __pos, size_type __n, const value_type& __x);
2009
2010	// called by insert(p,x)
2011	#if __cplusplus < 201103L
2012	iterator
2013	_M_insert_aux(iterator __pos, const value_type& __x);
2014	#else
2015	template<typename... _Args>
2016	iterator
2017	_M_insert_aux(iterator __pos, _Args&&... __args);
2018	#endif
2019
2020	// called by insert(p,n,x) via fill_insert
2021	void
2022	_M_insert_aux(iterator __pos, size_type __n, const value_type& __x);
2023
2024	// called by range_insert_aux for forward iterators
2025	template<typename _ForwardIterator>
2026	void
2027	_M_insert_aux(iterator __pos,
2028	_ForwardIterator __first, _ForwardIterator __last,
2029	size_type __n);
2030
2031
2032	// Internal erase functions follow.
2033
2034	void
2035	_M_destroy_data_aux(iterator __first, iterator __last);
2036
2037	// Called by ~deque().
2038	// NB: Doesn't deallocate the nodes.
2039	template<typename _Alloc1>
2040	void
2041	_M_destroy_data(iterator __first, iterator __last, const _Alloc1&)
2042	{ _M_destroy_data_aux(__first, __last); }
2043
2044	void
2045	_M_destroy_data(iterator __first, iterator __last,
2046	const std::allocator<_Tp>&)
2047	{
2048	if (!__has_trivial_destructor(value_type))
2049	_M_destroy_data_aux(__first, __last);
2050	}
2051
2052	// Called by erase(q1, q2).
2053	void
2054	_M_erase_at_begin(iterator __pos)
2055	{
2056	_M_destroy_data(begin(), __pos, _M_get_Tp_allocator());
2057	_M_destroy_nodes(this->_M_impl._M_start._M_node, __pos._M_node);
2058	this->_M_impl._M_start = __pos;
2059	}
2060
2061	// Called by erase(q1, q2), resize(), clear(), _M_assign_aux,
2062	// _M_fill_assign, operator=.
2063	void
2064	_M_erase_at_end(iterator __pos)
2065	{
2066	_M_destroy_data(__pos, end(), _M_get_Tp_allocator());
2067	_M_destroy_nodes(__pos._M_node + `1`,
2068	this->_M_impl._M_finish._M_node + `1`);
2069	this->_M_impl._M_finish = __pos;
2070	}
2071
2072	iterator
2073	_M_erase(iterator __pos);
2074
2075	iterator
2076	_M_erase(iterator __first, iterator __last);
2077
2078	#if __cplusplus >= 201103L
2079	// Called by resize(sz).
2080	void
2081	_M_default_append(size_type __n);
2082
2083	bool
2084	_M_shrink_to_fit();
2085	#endif
2086
2087	///@{
2088	/// Memory-handling helpers for the previous internal insert functions.
2089	iterator
2090	_M_reserve_elements_at_front(size_type __n)
2091	{
2092	const size_type __vacancies = this->_M_impl._M_start._M_cur
2093	- this->_M_impl._M_start._M_first;
2094	if (__n > __vacancies)
2095	_M_new_elements_at_front(new_elements: __n - __vacancies);
2096	return this->_M_impl._M_start - difference_type(__n);
2097	}
2098
2099	iterator
2100	_M_reserve_elements_at_back(size_type __n)
2101	{
2102	const size_type __vacancies = (this->_M_impl._M_finish._M_last
2103	- this->_M_impl._M_finish._M_cur) - `1`;
2104	if (__n > __vacancies)
2105	_M_new_elements_at_back(new_elements: __n - __vacancies);
2106	return this->_M_impl._M_finish + difference_type(__n);
2107	}
2108
2109	void
2110	_M_new_elements_at_front(size_type __new_elements);
2111
2112	void
2113	_M_new_elements_at_back(size_type __new_elements);
2114	///@}
2115
2116
2117	///@{
2118	/**
2119	* @brief Memory-handling helpers for the major %map.
2120	*
2121	* Makes sure the _M_map has space for new nodes. Does not
2122	* actually add the nodes. Can invalidate _M_map pointers.
2123	* (And consequently, %deque iterators.)
2124	*/
2125	void
2126	_M_reserve_map_at_back(size_type __nodes_to_add = `1`)
2127	{
2128	if (__nodes_to_add + `1` > this->_M_impl._M_map_size
2129	- (this->_M_impl._M_finish._M_node - this->_M_impl._M_map))
2130	_M_reallocate_map(__nodes_to_add, add_at_front: false);
2131	}
2132
2133	void
2134	_M_reserve_map_at_front(size_type __nodes_to_add = `1`)
2135	{
2136	if (__nodes_to_add > size_type(this->_M_impl._M_start._M_node
2137	- this->_M_impl._M_map))
2138	_M_reallocate_map(__nodes_to_add, add_at_front: true);
2139	}
2140
2141	void
2142	_M_reallocate_map(size_type __nodes_to_add, bool __add_at_front);
2143	///@}
2144
2145	#if __cplusplus >= 201103L
2146	// Constant-time, nothrow move assignment when source object's memory
2147	// can be moved because the allocators are equal.
2148	void
2149	_M_move_assign1(deque&& __x, / always equal: / true_type) noexcept
2150	{
2151	this->_M_impl._M_swap_data(__x._M_impl);
2152	__x.clear();
2153	std::__alloc_on_move(_M_get_Tp_allocator(), __x._M_get_Tp_allocator());
2154	}
2155
2156	// When the allocators are not equal the operation could throw, because
2157	// we might need to allocate a new map for __x after moving from it
2158	// or we might need to allocate new elements for this.*
2159	void
2160	_M_move_assign1(deque&& __x, / always equal: / false_type)
2161	{
2162	if (_M_get_Tp_allocator() == __x._M_get_Tp_allocator())
2163	return _M_move_assign1(std::move(__x), true_type ());
2164
2165	constexpr bool __move_storage =
2166	_Alloc_traits::_S_propagate_on_move_assign();
2167	_M_move_assign2(std::move(__x), __bool_constant<__move_storage>());
2168	}
2169
2170	// Destroy all elements and deallocate all memory, then replace
2171	// with elements created from __args.
2172	template<typename... _Args>
2173	void
2174	_M_replace_map(_Args&&... __args)
2175	{
2176	// Create new data first, so if allocation fails there are no effects.
2177	deque __newobj(std::forward<_Args>(__args)...);
2178	// Free existing storage using existing allocator.
2179	clear();
2180	_M_deallocate_node(begin()._M_node); // one node left after clear()*
2181	_M_deallocate_map(this->_M_impl._M_map, this->_M_impl._M_map_size);
2182	this->_M_impl._M_map = nullptr;
2183	this->_M_impl._M_map_size = `0`;
2184	// Take ownership of replacement memory.
2185	this->_M_impl._M_swap_data(__newobj._M_impl);
2186	}
2187
2188	// Do move assignment when the allocator propagates.
2189	void
2190	_M_move_assign2(deque&& __x, / propagate: / true_type)
2191	{
2192	// Make a copy of the original allocator state.
2193	auto __alloc = __x._M_get_Tp_allocator();
2194	// The allocator propagates so storage can be moved from __x,
2195	// leaving __x in a valid empty state with a moved-from allocator.
2196	_M_replace_map(std::move(__x));
2197	// Move the corresponding allocator state too.
2198	_M_get_Tp_allocator() = std::move(__alloc);
2199	}
2200
2201	// Do move assignment when it may not be possible to move source
2202	// object's memory, resulting in a linear-time operation.
2203	void
2204	_M_move_assign2(deque&& __x, / propagate: / false_type)
2205	{
2206	if (__x._M_get_Tp_allocator() == this->_M_get_Tp_allocator())
2207	{
2208	// The allocators are equal so storage can be moved from __x,
2209	// leaving __x in a valid empty state with its current allocator.
2210	_M_replace_map(std::move(__x), __x.get_allocator());
2211	}
2212	else
2213	{
2214	// The rvalue's allocator cannot be moved and is not equal,
2215	// so we need to individually move each element.
2216	_M_assign_aux(std::make_move_iterator(__x.begin()),
2217	std::make_move_iterator(__x.end()),
2218	std::random_access_iterator_tag ());
2219	__x.clear();
2220	}
2221	}
2222	#endif
2223	};
2224
2225	#if __cpp_deduction_guides >= 201606
2226	template<typename _InputIterator, typename _ValT
2227	= typename iterator_traits<_InputIterator>::value_type,
2228	typename _Allocator = allocator<_ValT>,
2229	typename = _RequireInputIter<_InputIterator>,
2230	typename = _RequireAllocator<_Allocator>>
2231	deque(_InputIterator, _InputIterator, _Allocator = _Allocator())
2232	-> deque<_ValT, _Allocator>;
2233	#endif
2234
2235	/**
2236	* @brief Deque equality comparison.
2237	* @param __x A %deque.
2238	* @param __y A %deque of the same type as @a __x.
2239	* @return True iff the size and elements of the deques are equal.
2240	*
2241	* This is an equivalence relation. It is linear in the size of the
2242	* deques. Deques are considered equivalent if their sizes are equal,
2243	* and if corresponding elements compare equal.
2244	*/
2245	template<typename _Tp, typename _Alloc>
2246	inline bool
2247	operator==(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2248	{ return __x.size() == __y.size()
2249	&& std::equal(__x.begin(), __x.end(), __y.begin()); }
2250
2251	#if __cpp_lib_three_way_comparison
2252	/**
2253	* @brief Deque ordering relation.
2254	* @param __x A `deque`.
2255	* @param __y A `deque` of the same type as `__x`.
2256	* @return A value indicating whether `__x` is less than, equal to,
2257	* greater than, or incomparable with `__y`.
2258	*
2259	* See `std::lexicographical_compare_three_way()` for how the determination
2260	* is made. This operator is used to synthesize relational operators like
2261	* `<` and `>=` etc.
2262	*/
2263	template<typename _Tp, typename _Alloc>
2264	inline __detail::__synth3way_t<_Tp>
2265	operator<=>(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2266	{
2267	return std::lexicographical_compare_three_way(__x.begin(), __x.end(),
2268	__y.begin(), __y.end(),
2269	__detail::__synth3way);
2270	}
2271	#else
2272	/**
2273	* @brief Deque ordering relation.
2274	* @param __x A %deque.
2275	* @param __y A %deque of the same type as @a __x.
2276	* @return True iff @a x is lexicographically less than @a __y.
2277	*
2278	* This is a total ordering relation. It is linear in the size of the
2279	* deques. The elements must be comparable with @c <.
2280	*
2281	* See std::lexicographical_compare() for how the determination is made.
2282	*/
2283	template<typename _Tp, typename _Alloc>
2284	inline bool
2285	operator<(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2286	{ return std::lexicographical_compare(__x.begin(), __x.end(),
2287	__y.begin(), __y.end()); }
2288
2289	/// Based on operator==
2290	template<typename _Tp, typename _Alloc>
2291	inline bool
2292	operator!=(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2293	{ return !(__x == __y); }
2294
2295	/// Based on operator<
2296	template<typename _Tp, typename _Alloc>
2297	inline bool
2298	operator>(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2299	{ return __y < __x; }
2300
2301	/// Based on operator<
2302	template<typename _Tp, typename _Alloc>
2303	inline bool
2304	operator<=(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2305	{ return !(__y < __x); }
2306
2307	/// Based on operator<
2308	template<typename _Tp, typename _Alloc>
2309	inline bool
2310	operator>=(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
2311	{ return !(__x < __y); }
2312	#endif // three-way comparison
2313
2314	/// See std::deque::swap().
2315	template<typename _Tp, typename _Alloc>
2316	inline void
2317	swap(deque<_Tp,_Alloc>& __x, deque<_Tp,_Alloc>& __y)
2318	_GLIBCXX_NOEXCEPT_IF(noexcept(__x.swap(__y)))
2319	{ __x.swap(__y); }
2320
2321	#undef _GLIBCXX_DEQUE_BUF_SIZE
2322
2323	_GLIBCXX_END_NAMESPACE_CONTAINER
2324
2325	#if __cplusplus >= 201103L
2326	// std::allocator is safe, but it is not the only allocator
2327	// for which this is valid.
2328	template<class _Tp>
2329	struct __is_bitwise_relocatable<_GLIBCXX_STD_C::deque<_Tp>>
2330	: true_type { };
2331	#endif
2332
2333	_GLIBCXX_END_NAMESPACE_VERSION
2334	} // namespace std
2335
2336	#endif /* _STL_DEQUE_H */
2337

Source File include/c++/11/bits/stl_deque.hHome Page Browse Root

Source File include/c++/11/bits/stl_deque.h
Home Page Browse Root