1 // Vector 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) 1996
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_vector.h
52  *  This is an internal header file, included by other library headers.
53  *  Do not attempt to use it directly. @headername{vector}
54  */
55 
56 #ifndef _STL_VECTOR_H
57 #define _STL_VECTOR_H 1
58 
59 #include <bits/stl_iterator_base_funcs.h>
60 #include <bits/functexcept.h>
61 #include <bits/concept_check.h>
62 #if __cplusplus >= 201103L
63 #include <initializer_list>
64 #endif
65 #if __cplusplus > 201703L
66 # include <compare>
67 #endif
68 
69 #include <debug/assertions.h>
70 
71 #if _GLIBCXX_SANITIZE_STD_ALLOCATOR && _GLIBCXX_SANITIZE_VECTOR
72 extern "C" void
73 __sanitizer_annotate_contiguous_container(const void*, const void*,
74 					  const void*, const void*);
75 #endif
76 
_GLIBCXX_VISIBILITY(default)77 namespace std _GLIBCXX_VISIBILITY(default)
78 {
79 _GLIBCXX_BEGIN_NAMESPACE_VERSION
80 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
81 
82   /// See bits/stl_deque.h's _Deque_base for an explanation.
83   template<typename _Tp, typename _Alloc>
84     struct _Vector_base
85     {
86       typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
87 	rebind<_Tp>::other _Tp_alloc_type;
88       typedef typename __gnu_cxx::__alloc_traits<_Tp_alloc_type>::pointer
89        	pointer;
90 
91       struct _Vector_impl_data
92       {
93 	pointer _M_start;
94 	pointer _M_finish;
95 	pointer _M_end_of_storage;
96 
97 	_GLIBCXX20_CONSTEXPR
98 	_Vector_impl_data() _GLIBCXX_NOEXCEPT
99 	: _M_start(), _M_finish(), _M_end_of_storage()
100 	{ }
101 
102 #if __cplusplus >= 201103L
103 	_GLIBCXX20_CONSTEXPR
104 	_Vector_impl_data(_Vector_impl_data&& __x) noexcept
105 	: _M_start(__x._M_start), _M_finish(__x._M_finish),
106 	  _M_end_of_storage(__x._M_end_of_storage)
107 	{ __x._M_start = __x._M_finish = __x._M_end_of_storage = pointer(); }
108 #endif
109 
110 	_GLIBCXX20_CONSTEXPR
111 	void
112 	_M_copy_data(_Vector_impl_data const& __x) _GLIBCXX_NOEXCEPT
113 	{
114 	  _M_start = __x._M_start;
115 	  _M_finish = __x._M_finish;
116 	  _M_end_of_storage = __x._M_end_of_storage;
117 	}
118 
119 	_GLIBCXX20_CONSTEXPR
120 	void
121 	_M_swap_data(_Vector_impl_data& __x) _GLIBCXX_NOEXCEPT
122 	{
123 	  // Do not use std::swap(_M_start, __x._M_start), etc as it loses
124 	  // information used by TBAA.
125 	  _Vector_impl_data __tmp;
126 	  __tmp._M_copy_data(*this);
127 	  _M_copy_data(__x);
128 	  __x._M_copy_data(__tmp);
129 	}
130       };
131 
132       struct _Vector_impl
133 	: public _Tp_alloc_type, public _Vector_impl_data
134       {
135 	_GLIBCXX20_CONSTEXPR
136 	_Vector_impl() _GLIBCXX_NOEXCEPT_IF(
137 	    is_nothrow_default_constructible<_Tp_alloc_type>::value)
138 	: _Tp_alloc_type()
139 	{ }
140 
141 	_GLIBCXX20_CONSTEXPR
142 	_Vector_impl(_Tp_alloc_type const& __a) _GLIBCXX_NOEXCEPT
143 	: _Tp_alloc_type(__a)
144 	{ }
145 
146 #if __cplusplus >= 201103L
147 	// Not defaulted, to enforce noexcept(true) even when
148 	// !is_nothrow_move_constructible<_Tp_alloc_type>.
149 	_GLIBCXX20_CONSTEXPR
150 	_Vector_impl(_Vector_impl&& __x) noexcept
151 	: _Tp_alloc_type(std::move(__x)), _Vector_impl_data(std::move(__x))
152 	{ }
153 
154 	_GLIBCXX20_CONSTEXPR
155 	_Vector_impl(_Tp_alloc_type&& __a) noexcept
156 	: _Tp_alloc_type(std::move(__a))
157 	{ }
158 
159 	_GLIBCXX20_CONSTEXPR
160 	_Vector_impl(_Tp_alloc_type&& __a, _Vector_impl&& __rv) noexcept
161 	: _Tp_alloc_type(std::move(__a)), _Vector_impl_data(std::move(__rv))
162 	{ }
163 #endif
164 
165 #if _GLIBCXX_SANITIZE_STD_ALLOCATOR && _GLIBCXX_SANITIZE_VECTOR
166 	template<typename = _Tp_alloc_type>
167 	  struct _Asan
168 	  {
169 	    typedef typename __gnu_cxx::__alloc_traits<_Tp_alloc_type>
170 	      ::size_type size_type;
171 
172 	    static _GLIBCXX20_CONSTEXPR void
173 	    _S_shrink(_Vector_impl&, size_type) { }
174 	    static _GLIBCXX20_CONSTEXPR void
175 	    _S_on_dealloc(_Vector_impl&) { }
176 
177 	    typedef _Vector_impl& _Reinit;
178 
179 	    struct _Grow
180 	    {
181 	      _GLIBCXX20_CONSTEXPR _Grow(_Vector_impl&, size_type) { }
182 	      _GLIBCXX20_CONSTEXPR void _M_grew(size_type) { }
183 	    };
184 	  };
185 
186 	// Enable ASan annotations for memory obtained from std::allocator.
187 	template<typename _Up>
188 	  struct _Asan<allocator<_Up> >
189 	  {
190 	    typedef typename __gnu_cxx::__alloc_traits<_Tp_alloc_type>
191 	      ::size_type size_type;
192 
193 	    // Adjust ASan annotation for [_M_start, _M_end_of_storage) to
194 	    // mark end of valid region as __curr instead of __prev.
195 	    static _GLIBCXX20_CONSTEXPR void
196 	    _S_adjust(_Vector_impl& __impl, pointer __prev, pointer __curr)
197 	    {
198 #if __cpp_lib_is_constant_evaluated
199 	      if (std::is_constant_evaluated())
200 		return;
201 #endif
202 	      __sanitizer_annotate_contiguous_container(__impl._M_start,
203 		  __impl._M_end_of_storage, __prev, __curr);
204 	    }
205 
206 	    static _GLIBCXX20_CONSTEXPR void
207 	    _S_grow(_Vector_impl& __impl, size_type __n)
208 	    { _S_adjust(__impl, __impl._M_finish, __impl._M_finish + __n); }
209 
210 	    static _GLIBCXX20_CONSTEXPR void
211 	    _S_shrink(_Vector_impl& __impl, size_type __n)
212 	    { _S_adjust(__impl, __impl._M_finish + __n, __impl._M_finish); }
213 
214 	    static _GLIBCXX20_CONSTEXPR void
215 	    _S_on_dealloc(_Vector_impl& __impl)
216 	    {
217 	      if (__impl._M_start)
218 		_S_adjust(__impl, __impl._M_finish, __impl._M_end_of_storage);
219 	    }
220 
221 	    // Used on reallocation to tell ASan unused capacity is invalid.
222 	    struct _Reinit
223 	    {
224 	      explicit _GLIBCXX20_CONSTEXPR
225 	      _Reinit(_Vector_impl& __impl) : _M_impl(__impl)
226 	      {
227 		// Mark unused capacity as valid again before deallocating it.
228 		_S_on_dealloc(_M_impl);
229 	      }
230 
231 	      _GLIBCXX20_CONSTEXPR
232 	      ~_Reinit()
233 	      {
234 		// Mark unused capacity as invalid after reallocation.
235 		if (_M_impl._M_start)
236 		  _S_adjust(_M_impl, _M_impl._M_end_of_storage,
237 			    _M_impl._M_finish);
238 	      }
239 
240 	      _Vector_impl& _M_impl;
241 
242 #if __cplusplus >= 201103L
243 	      _Reinit(const _Reinit&) = delete;
244 	      _Reinit& operator=(const _Reinit&) = delete;
245 #endif
246 	    };
247 
248 	    // Tell ASan when unused capacity is initialized to be valid.
249 	    struct _Grow
250 	    {
251 	      _GLIBCXX20_CONSTEXPR
252 	      _Grow(_Vector_impl& __impl, size_type __n)
253 	      : _M_impl(__impl), _M_n(__n)
254 	      { _S_grow(_M_impl, __n); }
255 
256 	      _GLIBCXX20_CONSTEXPR
257 	      ~_Grow() { if (_M_n) _S_shrink(_M_impl, _M_n); }
258 
259 	      _GLIBCXX20_CONSTEXPR
260 	      void _M_grew(size_type __n) { _M_n -= __n; }
261 
262 #if __cplusplus >= 201103L
263 	      _Grow(const _Grow&) = delete;
264 	      _Grow& operator=(const _Grow&) = delete;
265 #endif
266 	    private:
267 	      _Vector_impl& _M_impl;
268 	      size_type _M_n;
269 	    };
270 	  };
271 
272 #define _GLIBCXX_ASAN_ANNOTATE_REINIT \
273   typename _Base::_Vector_impl::template _Asan<>::_Reinit const \
274 	__attribute__((__unused__)) __reinit_guard(this->_M_impl)
275 #define _GLIBCXX_ASAN_ANNOTATE_GROW(n) \
276   typename _Base::_Vector_impl::template _Asan<>::_Grow \
277 	__attribute__((__unused__)) __grow_guard(this->_M_impl, (n))
278 #define _GLIBCXX_ASAN_ANNOTATE_GREW(n) __grow_guard._M_grew(n)
279 #define _GLIBCXX_ASAN_ANNOTATE_SHRINK(n) \
280   _Base::_Vector_impl::template _Asan<>::_S_shrink(this->_M_impl, n)
281 #define _GLIBCXX_ASAN_ANNOTATE_BEFORE_DEALLOC \
282   _Base::_Vector_impl::template _Asan<>::_S_on_dealloc(this->_M_impl)
283 #else // ! (_GLIBCXX_SANITIZE_STD_ALLOCATOR && _GLIBCXX_SANITIZE_VECTOR)
284 #define _GLIBCXX_ASAN_ANNOTATE_REINIT
285 #define _GLIBCXX_ASAN_ANNOTATE_GROW(n)
286 #define _GLIBCXX_ASAN_ANNOTATE_GREW(n)
287 #define _GLIBCXX_ASAN_ANNOTATE_SHRINK(n)
288 #define _GLIBCXX_ASAN_ANNOTATE_BEFORE_DEALLOC
289 #endif // _GLIBCXX_SANITIZE_STD_ALLOCATOR && _GLIBCXX_SANITIZE_VECTOR
290       };
291 
292     public:
293       typedef _Alloc allocator_type;
294 
295       _GLIBCXX20_CONSTEXPR
296       _Tp_alloc_type&
297       _M_get_Tp_allocator() _GLIBCXX_NOEXCEPT
298       { return this->_M_impl; }
299 
300       _GLIBCXX20_CONSTEXPR
301       const _Tp_alloc_type&
302       _M_get_Tp_allocator() const _GLIBCXX_NOEXCEPT
303       { return this->_M_impl; }
304 
305       _GLIBCXX20_CONSTEXPR
306       allocator_type
307       get_allocator() const _GLIBCXX_NOEXCEPT
308       { return allocator_type(_M_get_Tp_allocator()); }
309 
310 #if __cplusplus >= 201103L
311       _Vector_base() = default;
312 #else
313       _Vector_base() { }
314 #endif
315 
316       _GLIBCXX20_CONSTEXPR
317       _Vector_base(const allocator_type& __a) _GLIBCXX_NOEXCEPT
318       : _M_impl(__a) { }
319 
320       // Kept for ABI compatibility.
321 #if !_GLIBCXX_INLINE_VERSION
322       _GLIBCXX20_CONSTEXPR
323       _Vector_base(size_t __n)
324       : _M_impl()
325       { _M_create_storage(__n); }
326 #endif
327 
328       _GLIBCXX20_CONSTEXPR
329       _Vector_base(size_t __n, const allocator_type& __a)
330       : _M_impl(__a)
331       { _M_create_storage(__n); }
332 
333 #if __cplusplus >= 201103L
334       _Vector_base(_Vector_base&&) = default;
335 
336       // Kept for ABI compatibility.
337 # if !_GLIBCXX_INLINE_VERSION
338       _GLIBCXX20_CONSTEXPR
339       _Vector_base(_Tp_alloc_type&& __a) noexcept
340       : _M_impl(std::move(__a)) { }
341 
342       _GLIBCXX20_CONSTEXPR
343       _Vector_base(_Vector_base&& __x, const allocator_type& __a)
344       : _M_impl(__a)
345       {
346 	if (__x.get_allocator() == __a)
347 	  this->_M_impl._M_swap_data(__x._M_impl);
348 	else
349 	  {
350 	    size_t __n = __x._M_impl._M_finish - __x._M_impl._M_start;
351 	    _M_create_storage(__n);
352 	  }
353       }
354 # endif
355 
356       _GLIBCXX20_CONSTEXPR
357       _Vector_base(const allocator_type& __a, _Vector_base&& __x)
358       : _M_impl(_Tp_alloc_type(__a), std::move(__x._M_impl))
359       { }
360 #endif
361 
362       _GLIBCXX20_CONSTEXPR
363       ~_Vector_base() _GLIBCXX_NOEXCEPT
364       {
365 	_M_deallocate(_M_impl._M_start,
366 		      _M_impl._M_end_of_storage - _M_impl._M_start);
367       }
368 
369     public:
370       _Vector_impl _M_impl;
371 
372       _GLIBCXX20_CONSTEXPR
373       pointer
374       _M_allocate(size_t __n)
375       {
376 	typedef __gnu_cxx::__alloc_traits<_Tp_alloc_type> _Tr;
377 	return __n != 0 ? _Tr::allocate(_M_impl, __n) : pointer();
378       }
379 
380       _GLIBCXX20_CONSTEXPR
381       void
382       _M_deallocate(pointer __p, size_t __n)
383       {
384 	typedef __gnu_cxx::__alloc_traits<_Tp_alloc_type> _Tr;
385 	if (__p)
386 	  _Tr::deallocate(_M_impl, __p, __n);
387       }
388 
389     protected:
390       _GLIBCXX20_CONSTEXPR
391       void
392       _M_create_storage(size_t __n)
393       {
394 	this->_M_impl._M_start = this->_M_allocate(__n);
395 	this->_M_impl._M_finish = this->_M_impl._M_start;
396 	this->_M_impl._M_end_of_storage = this->_M_impl._M_start + __n;
397       }
398     };
399 
400   /**
401    *  @brief A standard container which offers fixed time access to
402    *  individual elements in any order.
403    *
404    *  @ingroup sequences
405    *
406    *  @tparam _Tp  Type of element.
407    *  @tparam _Alloc  Allocator type, defaults to allocator<_Tp>.
408    *
409    *  Meets the requirements of a <a href="tables.html#65">container</a>, a
410    *  <a href="tables.html#66">reversible container</a>, and a
411    *  <a href="tables.html#67">sequence</a>, including the
412    *  <a href="tables.html#68">optional sequence requirements</a> with the
413    *  %exception of @c push_front and @c pop_front.
414    *
415    *  In some terminology a %vector can be described as a dynamic
416    *  C-style array, it offers fast and efficient access to individual
417    *  elements in any order and saves the user from worrying about
418    *  memory and size allocation.  Subscripting ( @c [] ) access is
419    *  also provided as with C-style arrays.
420   */
421   template<typename _Tp, typename _Alloc = std::allocator<_Tp> >
422     class vector : protected _Vector_base<_Tp, _Alloc>
423     {
424 #ifdef _GLIBCXX_CONCEPT_CHECKS
425       // Concept requirements.
426       typedef typename _Alloc::value_type		_Alloc_value_type;
427 # if __cplusplus < 201103L
428       __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
429 # endif
430       __glibcxx_class_requires2(_Tp, _Alloc_value_type, _SameTypeConcept)
431 #endif
432 
433 #if __cplusplus >= 201103L
434       static_assert(is_same<typename remove_cv<_Tp>::type, _Tp>::value,
435 	  "std::vector must have a non-const, non-volatile value_type");
436 # if __cplusplus > 201703L || defined __STRICT_ANSI__
437       static_assert(is_same<typename _Alloc::value_type, _Tp>::value,
438 	  "std::vector must have the same value_type as its allocator");
439 # endif
440 #endif
441 
442       typedef _Vector_base<_Tp, _Alloc>			_Base;
443       typedef typename _Base::_Tp_alloc_type		_Tp_alloc_type;
444       typedef __gnu_cxx::__alloc_traits<_Tp_alloc_type>	_Alloc_traits;
445 
446     public:
447       typedef _Tp					value_type;
448       typedef typename _Base::pointer			pointer;
449       typedef typename _Alloc_traits::const_pointer	const_pointer;
450       typedef typename _Alloc_traits::reference		reference;
451       typedef typename _Alloc_traits::const_reference	const_reference;
452       typedef __gnu_cxx::__normal_iterator<pointer, vector> iterator;
453       typedef __gnu_cxx::__normal_iterator<const_pointer, vector>
454       const_iterator;
455       typedef std::reverse_iterator<const_iterator>	const_reverse_iterator;
456       typedef std::reverse_iterator<iterator>		reverse_iterator;
457       typedef size_t					size_type;
458       typedef ptrdiff_t					difference_type;
459       typedef _Alloc					allocator_type;
460 
461     private:
462 #if __cplusplus >= 201103L
463       static constexpr bool
464       _S_nothrow_relocate(true_type)
465       {
466 	return noexcept(std::__relocate_a(std::declval<pointer>(),
467 					  std::declval<pointer>(),
468 					  std::declval<pointer>(),
469 					  std::declval<_Tp_alloc_type&>()));
470       }
471 
472       static constexpr bool
473       _S_nothrow_relocate(false_type)
474       { return false; }
475 
476       static constexpr bool
477       _S_use_relocate()
478       {
479 	// Instantiating std::__relocate_a might cause an error outside the
480 	// immediate context (in __relocate_object_a's noexcept-specifier),
481 	// so only do it if we know the type can be move-inserted into *this.
482 	return _S_nothrow_relocate(__is_move_insertable<_Tp_alloc_type>{});
483       }
484 
485       static pointer
486       _S_do_relocate(pointer __first, pointer __last, pointer __result,
487 		     _Tp_alloc_type& __alloc, true_type) noexcept
488       {
489 	return std::__relocate_a(__first, __last, __result, __alloc);
490       }
491 
492       static pointer
493       _S_do_relocate(pointer, pointer, pointer __result,
494 		     _Tp_alloc_type&, false_type) noexcept
495       { return __result; }
496 
497       static _GLIBCXX20_CONSTEXPR pointer
498       _S_relocate(pointer __first, pointer __last, pointer __result,
499 		  _Tp_alloc_type& __alloc) noexcept
500       {
501 #if __cpp_if_constexpr
502 	// All callers have already checked _S_use_relocate() so just do it.
503 	return std::__relocate_a(__first, __last, __result, __alloc);
504 #else
505 	using __do_it = __bool_constant<_S_use_relocate()>;
506 	return _S_do_relocate(__first, __last, __result, __alloc, __do_it{});
507 #endif
508       }
509 #endif // C++11
510 
511     protected:
512       using _Base::_M_allocate;
513       using _Base::_M_deallocate;
514       using _Base::_M_impl;
515       using _Base::_M_get_Tp_allocator;
516 
517     public:
518       // [23.2.4.1] construct/copy/destroy
519       // (assign() and get_allocator() are also listed in this section)
520 
521       /**
522        *  @brief  Creates a %vector with no elements.
523        */
524 #if __cplusplus >= 201103L
525       vector() = default;
526 #else
527       vector() { }
528 #endif
529 
530       /**
531        *  @brief  Creates a %vector with no elements.
532        *  @param  __a  An allocator object.
533        */
534       explicit
535       _GLIBCXX20_CONSTEXPR
536       vector(const allocator_type& __a) _GLIBCXX_NOEXCEPT
537       : _Base(__a) { }
538 
539 #if __cplusplus >= 201103L
540       /**
541        *  @brief  Creates a %vector with default constructed elements.
542        *  @param  __n  The number of elements to initially create.
543        *  @param  __a  An allocator.
544        *
545        *  This constructor fills the %vector with @a __n default
546        *  constructed elements.
547        */
548       explicit
549       _GLIBCXX20_CONSTEXPR
550       vector(size_type __n, const allocator_type& __a = allocator_type())
551       : _Base(_S_check_init_len(__n, __a), __a)
552       { _M_default_initialize(__n); }
553 
554       /**
555        *  @brief  Creates a %vector with copies of an exemplar element.
556        *  @param  __n  The number of elements to initially create.
557        *  @param  __value  An element to copy.
558        *  @param  __a  An allocator.
559        *
560        *  This constructor fills the %vector with @a __n copies of @a __value.
561        */
562       _GLIBCXX20_CONSTEXPR
563       vector(size_type __n, const value_type& __value,
564 	     const allocator_type& __a = allocator_type())
565       : _Base(_S_check_init_len(__n, __a), __a)
566       { _M_fill_initialize(__n, __value); }
567 #else
568       /**
569        *  @brief  Creates a %vector with copies of an exemplar element.
570        *  @param  __n  The number of elements to initially create.
571        *  @param  __value  An element to copy.
572        *  @param  __a  An allocator.
573        *
574        *  This constructor fills the %vector with @a __n copies of @a __value.
575        */
576       explicit
577       vector(size_type __n, const value_type& __value = value_type(),
578 	     const allocator_type& __a = allocator_type())
579       : _Base(_S_check_init_len(__n, __a), __a)
580       { _M_fill_initialize(__n, __value); }
581 #endif
582 
583       /**
584        *  @brief  %Vector copy constructor.
585        *  @param  __x  A %vector of identical element and allocator types.
586        *
587        *  All the elements of @a __x are copied, but any unused capacity in
588        *  @a __x  will not be copied
589        *  (i.e. capacity() == size() in the new %vector).
590        *
591        *  The newly-created %vector uses a copy of the allocator object used
592        *  by @a __x (unless the allocator traits dictate a different object).
593        */
594       _GLIBCXX20_CONSTEXPR
595       vector(const vector& __x)
596       : _Base(__x.size(),
597 	_Alloc_traits::_S_select_on_copy(__x._M_get_Tp_allocator()))
598       {
599 	this->_M_impl._M_finish =
600 	  std::__uninitialized_copy_a(__x.begin(), __x.end(),
601 				      this->_M_impl._M_start,
602 				      _M_get_Tp_allocator());
603       }
604 
605 #if __cplusplus >= 201103L
606       /**
607        *  @brief  %Vector move constructor.
608        *
609        *  The newly-created %vector contains the exact contents of the
610        *  moved instance.
611        *  The contents of the moved instance are a valid, but unspecified
612        *  %vector.
613        */
614       vector(vector&&) noexcept = default;
615 
616       /// Copy constructor with alternative allocator
617       _GLIBCXX20_CONSTEXPR
618       vector(const vector& __x, const __type_identity_t<allocator_type>& __a)
619       : _Base(__x.size(), __a)
620       {
621 	this->_M_impl._M_finish =
622 	  std::__uninitialized_copy_a(__x.begin(), __x.end(),
623 				      this->_M_impl._M_start,
624 				      _M_get_Tp_allocator());
625       }
626 
627     private:
628       _GLIBCXX20_CONSTEXPR
629       vector(vector&& __rv, const allocator_type& __m, true_type) noexcept
630       : _Base(__m, std::move(__rv))
631       { }
632 
633       _GLIBCXX20_CONSTEXPR
634       vector(vector&& __rv, const allocator_type& __m, false_type)
635       : _Base(__m)
636       {
637 	if (__rv.get_allocator() == __m)
638 	  this->_M_impl._M_swap_data(__rv._M_impl);
639 	else if (!__rv.empty())
640 	  {
641 	    this->_M_create_storage(__rv.size());
642 	    this->_M_impl._M_finish =
643 	      std::__uninitialized_move_a(__rv.begin(), __rv.end(),
644 					  this->_M_impl._M_start,
645 					  _M_get_Tp_allocator());
646 	    __rv.clear();
647 	  }
648       }
649 
650     public:
651       /// Move constructor with alternative allocator
652       _GLIBCXX20_CONSTEXPR
653       vector(vector&& __rv, const __type_identity_t<allocator_type>& __m)
654       noexcept( noexcept(
655 	vector(std::declval<vector&&>(), std::declval<const allocator_type&>(),
656 	       std::declval<typename _Alloc_traits::is_always_equal>())) )
657       : vector(std::move(__rv), __m, typename _Alloc_traits::is_always_equal{})
658       { }
659 
660       /**
661        *  @brief  Builds a %vector from an initializer list.
662        *  @param  __l  An initializer_list.
663        *  @param  __a  An allocator.
664        *
665        *  Create a %vector consisting of copies of the elements in the
666        *  initializer_list @a __l.
667        *
668        *  This will call the element type's copy constructor N times
669        *  (where N is @a __l.size()) and do no memory reallocation.
670        */
671       _GLIBCXX20_CONSTEXPR
672       vector(initializer_list<value_type> __l,
673 	     const allocator_type& __a = allocator_type())
674       : _Base(__a)
675       {
676 	_M_range_initialize(__l.begin(), __l.end(),
677 			    random_access_iterator_tag());
678       }
679 #endif
680 
681       /**
682        *  @brief  Builds a %vector from a range.
683        *  @param  __first  An input iterator.
684        *  @param  __last  An input iterator.
685        *  @param  __a  An allocator.
686        *
687        *  Create a %vector consisting of copies of the elements from
688        *  [first,last).
689        *
690        *  If the iterators are forward, bidirectional, or
691        *  random-access, then this will call the elements' copy
692        *  constructor N times (where N is distance(first,last)) and do
693        *  no memory reallocation.  But if only input iterators are
694        *  used, then this will do at most 2N calls to the copy
695        *  constructor, and logN memory reallocations.
696        */
697 #if __cplusplus >= 201103L
698       template<typename _InputIterator,
699 	       typename = std::_RequireInputIter<_InputIterator>>
700 	_GLIBCXX20_CONSTEXPR
701 	vector(_InputIterator __first, _InputIterator __last,
702 	       const allocator_type& __a = allocator_type())
703 	: _Base(__a)
704 	{
705 	  _M_range_initialize(__first, __last,
706 			      std::__iterator_category(__first));
707 	}
708 #else
709       template<typename _InputIterator>
710 	vector(_InputIterator __first, _InputIterator __last,
711 	       const allocator_type& __a = allocator_type())
712 	: _Base(__a)
713 	{
714 	  // Check whether it's an integral type.  If so, it's not an iterator.
715 	  typedef typename std::__is_integer<_InputIterator>::__type _Integral;
716 	  _M_initialize_dispatch(__first, __last, _Integral());
717 	}
718 #endif
719 
720       /**
721        *  The dtor only erases the elements, and note that if the
722        *  elements themselves are pointers, the pointed-to memory is
723        *  not touched in any way.  Managing the pointer is the user's
724        *  responsibility.
725        */
726       _GLIBCXX20_CONSTEXPR
727       ~vector() _GLIBCXX_NOEXCEPT
728       {
729 	std::_Destroy(this->_M_impl._M_start, this->_M_impl._M_finish,
730 		      _M_get_Tp_allocator());
731 	_GLIBCXX_ASAN_ANNOTATE_BEFORE_DEALLOC;
732       }
733 
734       /**
735        *  @brief  %Vector assignment operator.
736        *  @param  __x  A %vector of identical element and allocator types.
737        *
738        *  All the elements of @a __x are copied, but any unused capacity in
739        *  @a __x will not be copied.
740        *
741        *  Whether the allocator is copied depends on the allocator traits.
742        */
743       _GLIBCXX20_CONSTEXPR
744       vector&
745       operator=(const vector& __x);
746 
747 #if __cplusplus >= 201103L
748       /**
749        *  @brief  %Vector move assignment operator.
750        *  @param  __x  A %vector of identical element and allocator types.
751        *
752        *  The contents of @a __x are moved into this %vector (without copying,
753        *  if the allocators permit it).
754        *  Afterwards @a __x is a valid, but unspecified %vector.
755        *
756        *  Whether the allocator is moved depends on the allocator traits.
757        */
758       _GLIBCXX20_CONSTEXPR
759       vector&
760       operator=(vector&& __x) noexcept(_Alloc_traits::_S_nothrow_move())
761       {
762 	constexpr bool __move_storage =
763 	  _Alloc_traits::_S_propagate_on_move_assign()
764 	  || _Alloc_traits::_S_always_equal();
765 	_M_move_assign(std::move(__x), __bool_constant<__move_storage>());
766 	return *this;
767       }
768 
769       /**
770        *  @brief  %Vector list assignment operator.
771        *  @param  __l  An initializer_list.
772        *
773        *  This function fills a %vector with copies of the elements in the
774        *  initializer list @a __l.
775        *
776        *  Note that the assignment completely changes the %vector and
777        *  that the resulting %vector's size is the same as the number
778        *  of elements assigned.
779        */
780       _GLIBCXX20_CONSTEXPR
781       vector&
782       operator=(initializer_list<value_type> __l)
783       {
784 	this->_M_assign_aux(__l.begin(), __l.end(),
785 			    random_access_iterator_tag());
786 	return *this;
787       }
788 #endif
789 
790       /**
791        *  @brief  Assigns a given value to a %vector.
792        *  @param  __n  Number of elements to be assigned.
793        *  @param  __val  Value to be assigned.
794        *
795        *  This function fills a %vector with @a __n copies of the given
796        *  value.  Note that the assignment completely changes the
797        *  %vector and that the resulting %vector's size is the same as
798        *  the number of elements assigned.
799        */
800       _GLIBCXX20_CONSTEXPR
801       void
802       assign(size_type __n, const value_type& __val)
803       { _M_fill_assign(__n, __val); }
804 
805       /**
806        *  @brief  Assigns a range to a %vector.
807        *  @param  __first  An input iterator.
808        *  @param  __last   An input iterator.
809        *
810        *  This function fills a %vector with copies of the elements in the
811        *  range [__first,__last).
812        *
813        *  Note that the assignment completely changes the %vector and
814        *  that the resulting %vector's size is the same as the number
815        *  of elements assigned.
816        */
817 #if __cplusplus >= 201103L
818       template<typename _InputIterator,
819 	       typename = std::_RequireInputIter<_InputIterator>>
820 	_GLIBCXX20_CONSTEXPR
821 	void
822 	assign(_InputIterator __first, _InputIterator __last)
823 	{ _M_assign_dispatch(__first, __last, __false_type()); }
824 #else
825       template<typename _InputIterator>
826 	void
827 	assign(_InputIterator __first, _InputIterator __last)
828 	{
829 	  // Check whether it's an integral type.  If so, it's not an iterator.
830 	  typedef typename std::__is_integer<_InputIterator>::__type _Integral;
831 	  _M_assign_dispatch(__first, __last, _Integral());
832 	}
833 #endif
834 
835 #if __cplusplus >= 201103L
836       /**
837        *  @brief  Assigns an initializer list to a %vector.
838        *  @param  __l  An initializer_list.
839        *
840        *  This function fills a %vector with copies of the elements in the
841        *  initializer list @a __l.
842        *
843        *  Note that the assignment completely changes the %vector and
844        *  that the resulting %vector's size is the same as the number
845        *  of elements assigned.
846        */
847       _GLIBCXX20_CONSTEXPR
848       void
849       assign(initializer_list<value_type> __l)
850       {
851 	this->_M_assign_aux(__l.begin(), __l.end(),
852 			    random_access_iterator_tag());
853       }
854 #endif
855 
856       /// Get a copy of the memory allocation object.
857       using _Base::get_allocator;
858 
859       // iterators
860       /**
861        *  Returns a read/write iterator that points to the first
862        *  element in the %vector.  Iteration is done in ordinary
863        *  element order.
864        */
865       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
866       iterator
867       begin() _GLIBCXX_NOEXCEPT
868       { return iterator(this->_M_impl._M_start); }
869 
870       /**
871        *  Returns a read-only (constant) iterator that points to the
872        *  first element in the %vector.  Iteration is done in ordinary
873        *  element order.
874        */
875       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
876       const_iterator
877       begin() const _GLIBCXX_NOEXCEPT
878       { return const_iterator(this->_M_impl._M_start); }
879 
880       /**
881        *  Returns a read/write iterator that points one past the last
882        *  element in the %vector.  Iteration is done in ordinary
883        *  element order.
884        */
885       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
886       iterator
887       end() _GLIBCXX_NOEXCEPT
888       { return iterator(this->_M_impl._M_finish); }
889 
890       /**
891        *  Returns a read-only (constant) iterator that points one past
892        *  the last element in the %vector.  Iteration is done in
893        *  ordinary element order.
894        */
895       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
896       const_iterator
897       end() const _GLIBCXX_NOEXCEPT
898       { return const_iterator(this->_M_impl._M_finish); }
899 
900       /**
901        *  Returns a read/write reverse iterator that points to the
902        *  last element in the %vector.  Iteration is done in reverse
903        *  element order.
904        */
905       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
906       reverse_iterator
907       rbegin() _GLIBCXX_NOEXCEPT
908       { return reverse_iterator(end()); }
909 
910       /**
911        *  Returns a read-only (constant) reverse iterator that points
912        *  to the last element in the %vector.  Iteration is done in
913        *  reverse element order.
914        */
915       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
916       const_reverse_iterator
917       rbegin() const _GLIBCXX_NOEXCEPT
918       { return const_reverse_iterator(end()); }
919 
920       /**
921        *  Returns a read/write reverse iterator that points to one
922        *  before the first element in the %vector.  Iteration is done
923        *  in reverse element order.
924        */
925       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
926       reverse_iterator
927       rend() _GLIBCXX_NOEXCEPT
928       { return reverse_iterator(begin()); }
929 
930       /**
931        *  Returns a read-only (constant) reverse iterator that points
932        *  to one before the first element in the %vector.  Iteration
933        *  is done in reverse element order.
934        */
935       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
936       const_reverse_iterator
937       rend() const _GLIBCXX_NOEXCEPT
938       { return const_reverse_iterator(begin()); }
939 
940 #if __cplusplus >= 201103L
941       /**
942        *  Returns a read-only (constant) iterator that points to the
943        *  first element in the %vector.  Iteration is done in ordinary
944        *  element order.
945        */
946       [[__nodiscard__]] _GLIBCXX20_CONSTEXPR
947       const_iterator
948       cbegin() const noexcept
949       { return const_iterator(this->_M_impl._M_start); }
950 
951       /**
952        *  Returns a read-only (constant) iterator that points one past
953        *  the last element in the %vector.  Iteration is done in
954        *  ordinary element order.
955        */
956       [[__nodiscard__]] _GLIBCXX20_CONSTEXPR
957       const_iterator
958       cend() const noexcept
959       { return const_iterator(this->_M_impl._M_finish); }
960 
961       /**
962        *  Returns a read-only (constant) reverse iterator that points
963        *  to the last element in the %vector.  Iteration is done in
964        *  reverse element order.
965        */
966       [[__nodiscard__]] _GLIBCXX20_CONSTEXPR
967       const_reverse_iterator
968       crbegin() const noexcept
969       { return const_reverse_iterator(end()); }
970 
971       /**
972        *  Returns a read-only (constant) reverse iterator that points
973        *  to one before the first element in the %vector.  Iteration
974        *  is done in reverse element order.
975        */
976       [[__nodiscard__]] _GLIBCXX20_CONSTEXPR
977       const_reverse_iterator
978       crend() const noexcept
979       { return const_reverse_iterator(begin()); }
980 #endif
981 
982       // [23.2.4.2] capacity
983       /**  Returns the number of elements in the %vector.  */
984       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
985       size_type
986       size() const _GLIBCXX_NOEXCEPT
987       { return size_type(this->_M_impl._M_finish - this->_M_impl._M_start); }
988 
989       /**  Returns the size() of the largest possible %vector.  */
990       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
991       size_type
992       max_size() const _GLIBCXX_NOEXCEPT
993       { return _S_max_size(_M_get_Tp_allocator()); }
994 
995 #if __cplusplus >= 201103L
996       /**
997        *  @brief  Resizes the %vector to the specified number of elements.
998        *  @param  __new_size  Number of elements the %vector should contain.
999        *
1000        *  This function will %resize the %vector to the specified
1001        *  number of elements.  If the number is smaller than the
1002        *  %vector's current size the %vector is truncated, otherwise
1003        *  default constructed elements are appended.
1004        */
1005       _GLIBCXX20_CONSTEXPR
1006       void
1007       resize(size_type __new_size)
1008       {
1009 	if (__new_size > size())
1010 	  _M_default_append(__new_size - size());
1011 	else if (__new_size < size())
1012 	  _M_erase_at_end(this->_M_impl._M_start + __new_size);
1013       }
1014 
1015       /**
1016        *  @brief  Resizes the %vector to the specified number of elements.
1017        *  @param  __new_size  Number of elements the %vector should contain.
1018        *  @param  __x  Data with which new elements should be populated.
1019        *
1020        *  This function will %resize the %vector to the specified
1021        *  number of elements.  If the number is smaller than the
1022        *  %vector's current size the %vector is truncated, otherwise
1023        *  the %vector is extended and new elements are populated with
1024        *  given data.
1025        */
1026       _GLIBCXX20_CONSTEXPR
1027       void
1028       resize(size_type __new_size, const value_type& __x)
1029       {
1030 	if (__new_size > size())
1031 	  _M_fill_insert(end(), __new_size - size(), __x);
1032 	else if (__new_size < size())
1033 	  _M_erase_at_end(this->_M_impl._M_start + __new_size);
1034       }
1035 #else
1036       /**
1037        *  @brief  Resizes the %vector to the specified number of elements.
1038        *  @param  __new_size  Number of elements the %vector should contain.
1039        *  @param  __x  Data with which new elements should be populated.
1040        *
1041        *  This function will %resize the %vector to the specified
1042        *  number of elements.  If the number is smaller than the
1043        *  %vector's current size the %vector is truncated, otherwise
1044        *  the %vector is extended and new elements are populated with
1045        *  given data.
1046        */
1047       _GLIBCXX20_CONSTEXPR
1048       void
1049       resize(size_type __new_size, value_type __x = value_type())
1050       {
1051 	if (__new_size > size())
1052 	  _M_fill_insert(end(), __new_size - size(), __x);
1053 	else if (__new_size < size())
1054 	  _M_erase_at_end(this->_M_impl._M_start + __new_size);
1055       }
1056 #endif
1057 
1058 #if __cplusplus >= 201103L
1059       /**  A non-binding request to reduce capacity() to size().  */
1060       _GLIBCXX20_CONSTEXPR
1061       void
1062       shrink_to_fit()
1063       { _M_shrink_to_fit(); }
1064 #endif
1065 
1066       /**
1067        *  Returns the total number of elements that the %vector can
1068        *  hold before needing to allocate more memory.
1069        */
1070       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1071       size_type
1072       capacity() const _GLIBCXX_NOEXCEPT
1073       { return size_type(this->_M_impl._M_end_of_storage
1074 			 - this->_M_impl._M_start); }
1075 
1076       /**
1077        *  Returns true if the %vector is empty.  (Thus begin() would
1078        *  equal end().)
1079        */
1080       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1081       bool
1082       empty() const _GLIBCXX_NOEXCEPT
1083       { return begin() == end(); }
1084 
1085       /**
1086        *  @brief  Attempt to preallocate enough memory for specified number of
1087        *          elements.
1088        *  @param  __n  Number of elements required.
1089        *  @throw  std::length_error  If @a n exceeds @c max_size().
1090        *
1091        *  This function attempts to reserve enough memory for the
1092        *  %vector to hold the specified number of elements.  If the
1093        *  number requested is more than max_size(), length_error is
1094        *  thrown.
1095        *
1096        *  The advantage of this function is that if optimal code is a
1097        *  necessity and the user can determine the number of elements
1098        *  that will be required, the user can reserve the memory in
1099        *  %advance, and thus prevent a possible reallocation of memory
1100        *  and copying of %vector data.
1101        */
1102       _GLIBCXX20_CONSTEXPR
1103       void
1104       reserve(size_type __n);
1105 
1106       // element access
1107       /**
1108        *  @brief  Subscript access to the data contained in the %vector.
1109        *  @param __n The index of the element for which data should be
1110        *  accessed.
1111        *  @return  Read/write reference to data.
1112        *
1113        *  This operator allows for easy, array-style, data access.
1114        *  Note that data access with this operator is unchecked and
1115        *  out_of_range lookups are not defined. (For checked lookups
1116        *  see at().)
1117        */
1118       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1119       reference
1120       operator[](size_type __n) _GLIBCXX_NOEXCEPT
1121       {
1122 	__glibcxx_requires_subscript(__n);
1123 	return *(this->_M_impl._M_start + __n);
1124       }
1125 
1126       /**
1127        *  @brief  Subscript access to the data contained in the %vector.
1128        *  @param __n The index of the element for which data should be
1129        *  accessed.
1130        *  @return  Read-only (constant) reference to data.
1131        *
1132        *  This operator allows for easy, array-style, data access.
1133        *  Note that data access with this operator is unchecked and
1134        *  out_of_range lookups are not defined. (For checked lookups
1135        *  see at().)
1136        */
1137       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1138       const_reference
1139       operator[](size_type __n) const _GLIBCXX_NOEXCEPT
1140       {
1141 	__glibcxx_requires_subscript(__n);
1142 	return *(this->_M_impl._M_start + __n);
1143       }
1144 
1145     protected:
1146       /// Safety check used only from at().
1147       _GLIBCXX20_CONSTEXPR
1148       void
1149       _M_range_check(size_type __n) const
1150       {
1151 	if (__n >= this->size())
1152 	  __throw_out_of_range_fmt(__N("vector::_M_range_check: __n "
1153 				       "(which is %zu) >= this->size() "
1154 				       "(which is %zu)"),
1155 				   __n, this->size());
1156       }
1157 
1158     public:
1159       /**
1160        *  @brief  Provides access to the data contained in the %vector.
1161        *  @param __n The index of the element for which data should be
1162        *  accessed.
1163        *  @return  Read/write reference to data.
1164        *  @throw  std::out_of_range  If @a __n is an invalid index.
1165        *
1166        *  This function provides for safer data access.  The parameter
1167        *  is first checked that it is in the range of the vector.  The
1168        *  function throws out_of_range if the check fails.
1169        */
1170       _GLIBCXX20_CONSTEXPR
1171       reference
1172       at(size_type __n)
1173       {
1174 	_M_range_check(__n);
1175 	return (*this)[__n];
1176       }
1177 
1178       /**
1179        *  @brief  Provides access to the data contained in the %vector.
1180        *  @param __n The index of the element for which data should be
1181        *  accessed.
1182        *  @return  Read-only (constant) reference to data.
1183        *  @throw  std::out_of_range  If @a __n is an invalid index.
1184        *
1185        *  This function provides for safer data access.  The parameter
1186        *  is first checked that it is in the range of the vector.  The
1187        *  function throws out_of_range if the check fails.
1188        */
1189       _GLIBCXX20_CONSTEXPR
1190       const_reference
1191       at(size_type __n) const
1192       {
1193 	_M_range_check(__n);
1194 	return (*this)[__n];
1195       }
1196 
1197       /**
1198        *  Returns a read/write reference to the data at the first
1199        *  element of the %vector.
1200        */
1201       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1202       reference
1203       front() _GLIBCXX_NOEXCEPT
1204       {
1205 	__glibcxx_requires_nonempty();
1206 	return *begin();
1207       }
1208 
1209       /**
1210        *  Returns a read-only (constant) reference to the data at the first
1211        *  element of the %vector.
1212        */
1213       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1214       const_reference
1215       front() const _GLIBCXX_NOEXCEPT
1216       {
1217 	__glibcxx_requires_nonempty();
1218 	return *begin();
1219       }
1220 
1221       /**
1222        *  Returns a read/write reference to the data at the last
1223        *  element of the %vector.
1224        */
1225       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1226       reference
1227       back() _GLIBCXX_NOEXCEPT
1228       {
1229 	__glibcxx_requires_nonempty();
1230 	return *(end() - 1);
1231       }
1232 
1233       /**
1234        *  Returns a read-only (constant) reference to the data at the
1235        *  last element of the %vector.
1236        */
1237       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1238       const_reference
1239       back() const _GLIBCXX_NOEXCEPT
1240       {
1241 	__glibcxx_requires_nonempty();
1242 	return *(end() - 1);
1243       }
1244 
1245       // _GLIBCXX_RESOLVE_LIB_DEFECTS
1246       // DR 464. Suggestion for new member functions in standard containers.
1247       // data access
1248       /**
1249        *   Returns a pointer such that [data(), data() + size()) is a valid
1250        *   range.  For a non-empty %vector, data() == &front().
1251        */
1252       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1253       _Tp*
1254       data() _GLIBCXX_NOEXCEPT
1255       { return _M_data_ptr(this->_M_impl._M_start); }
1256 
1257       _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1258       const _Tp*
1259       data() const _GLIBCXX_NOEXCEPT
1260       { return _M_data_ptr(this->_M_impl._M_start); }
1261 
1262       // [23.2.4.3] modifiers
1263       /**
1264        *  @brief  Add data to the end of the %vector.
1265        *  @param  __x  Data to be added.
1266        *
1267        *  This is a typical stack operation.  The function creates an
1268        *  element at the end of the %vector and assigns the given data
1269        *  to it.  Due to the nature of a %vector this operation can be
1270        *  done in constant time if the %vector has preallocated space
1271        *  available.
1272        */
1273       _GLIBCXX20_CONSTEXPR
1274       void
1275       push_back(const value_type& __x)
1276       {
1277 	if (this->_M_impl._M_finish != this->_M_impl._M_end_of_storage)
1278 	  {
1279 	    _GLIBCXX_ASAN_ANNOTATE_GROW(1);
1280 	    _Alloc_traits::construct(this->_M_impl, this->_M_impl._M_finish,
1281 				     __x);
1282 	    ++this->_M_impl._M_finish;
1283 	    _GLIBCXX_ASAN_ANNOTATE_GREW(1);
1284 	  }
1285 	else
1286 	  _M_realloc_insert(end(), __x);
1287       }
1288 
1289 #if __cplusplus >= 201103L
1290       _GLIBCXX20_CONSTEXPR
1291       void
1292       push_back(value_type&& __x)
1293       { emplace_back(std::move(__x)); }
1294 
1295       template<typename... _Args>
1296 #if __cplusplus > 201402L
1297 	_GLIBCXX20_CONSTEXPR
1298 	reference
1299 #else
1300 	void
1301 #endif
1302 	emplace_back(_Args&&... __args);
1303 #endif
1304 
1305       /**
1306        *  @brief  Removes last element.
1307        *
1308        *  This is a typical stack operation. It shrinks the %vector by one.
1309        *
1310        *  Note that no data is returned, and if the last element's
1311        *  data is needed, it should be retrieved before pop_back() is
1312        *  called.
1313        */
1314       _GLIBCXX20_CONSTEXPR
1315       void
1316       pop_back() _GLIBCXX_NOEXCEPT
1317       {
1318 	__glibcxx_requires_nonempty();
1319 	--this->_M_impl._M_finish;
1320 	_Alloc_traits::destroy(this->_M_impl, this->_M_impl._M_finish);
1321 	_GLIBCXX_ASAN_ANNOTATE_SHRINK(1);
1322       }
1323 
1324 #if __cplusplus >= 201103L
1325       /**
1326        *  @brief  Inserts an object in %vector before specified iterator.
1327        *  @param  __position  A const_iterator into the %vector.
1328        *  @param  __args  Arguments.
1329        *  @return  An iterator that points to the inserted data.
1330        *
1331        *  This function will insert an object of type T constructed
1332        *  with T(std::forward<Args>(args)...) before the specified location.
1333        *  Note that this kind of operation could be expensive for a %vector
1334        *  and if it is frequently used the user should consider using
1335        *  std::list.
1336        */
1337       template<typename... _Args>
1338 	_GLIBCXX20_CONSTEXPR
1339 	iterator
1340 	emplace(const_iterator __position, _Args&&... __args)
1341 	{ return _M_emplace_aux(__position, std::forward<_Args>(__args)...); }
1342 
1343       /**
1344        *  @brief  Inserts given value into %vector before specified iterator.
1345        *  @param  __position  A const_iterator into the %vector.
1346        *  @param  __x  Data to be inserted.
1347        *  @return  An iterator that points to the inserted data.
1348        *
1349        *  This function will insert a copy of the given value before
1350        *  the specified location.  Note that this kind of operation
1351        *  could be expensive for a %vector and if it is frequently
1352        *  used the user should consider using std::list.
1353        */
1354       _GLIBCXX20_CONSTEXPR
1355       iterator
1356       insert(const_iterator __position, const value_type& __x);
1357 #else
1358       /**
1359        *  @brief  Inserts given value into %vector before specified iterator.
1360        *  @param  __position  An iterator into the %vector.
1361        *  @param  __x  Data to be inserted.
1362        *  @return  An iterator that points to the inserted data.
1363        *
1364        *  This function will insert a copy of the given value before
1365        *  the specified location.  Note that this kind of operation
1366        *  could be expensive for a %vector and if it is frequently
1367        *  used the user should consider using std::list.
1368        */
1369       iterator
1370       insert(iterator __position, const value_type& __x);
1371 #endif
1372 
1373 #if __cplusplus >= 201103L
1374       /**
1375        *  @brief  Inserts given rvalue into %vector before specified iterator.
1376        *  @param  __position  A const_iterator into the %vector.
1377        *  @param  __x  Data to be inserted.
1378        *  @return  An iterator that points to the inserted data.
1379        *
1380        *  This function will insert a copy of the given rvalue before
1381        *  the specified location.  Note that this kind of operation
1382        *  could be expensive for a %vector and if it is frequently
1383        *  used the user should consider using std::list.
1384        */
1385       _GLIBCXX20_CONSTEXPR
1386       iterator
1387       insert(const_iterator __position, value_type&& __x)
1388       { return _M_insert_rval(__position, std::move(__x)); }
1389 
1390       /**
1391        *  @brief  Inserts an initializer_list into the %vector.
1392        *  @param  __position  An iterator into the %vector.
1393        *  @param  __l  An initializer_list.
1394        *
1395        *  This function will insert copies of the data in the
1396        *  initializer_list @a l into the %vector before the location
1397        *  specified by @a position.
1398        *
1399        *  Note that this kind of operation could be expensive for a
1400        *  %vector and if it is frequently used the user should
1401        *  consider using std::list.
1402        */
1403       _GLIBCXX20_CONSTEXPR
1404       iterator
1405       insert(const_iterator __position, initializer_list<value_type> __l)
1406       {
1407 	auto __offset = __position - cbegin();
1408 	_M_range_insert(begin() + __offset, __l.begin(), __l.end(),
1409 			std::random_access_iterator_tag());
1410 	return begin() + __offset;
1411       }
1412 #endif
1413 
1414 #if __cplusplus >= 201103L
1415       /**
1416        *  @brief  Inserts a number of copies of given data into the %vector.
1417        *  @param  __position  A const_iterator into the %vector.
1418        *  @param  __n  Number of elements to be inserted.
1419        *  @param  __x  Data to be inserted.
1420        *  @return  An iterator that points to the inserted data.
1421        *
1422        *  This function will insert a specified number of copies of
1423        *  the given data before the location specified by @a position.
1424        *
1425        *  Note that this kind of operation could be expensive for a
1426        *  %vector and if it is frequently used the user should
1427        *  consider using std::list.
1428        */
1429       _GLIBCXX20_CONSTEXPR
1430       iterator
1431       insert(const_iterator __position, size_type __n, const value_type& __x)
1432       {
1433 	difference_type __offset = __position - cbegin();
1434 	_M_fill_insert(begin() + __offset, __n, __x);
1435 	return begin() + __offset;
1436       }
1437 #else
1438       /**
1439        *  @brief  Inserts a number of copies of given data into the %vector.
1440        *  @param  __position  An iterator into the %vector.
1441        *  @param  __n  Number of elements to be inserted.
1442        *  @param  __x  Data to be inserted.
1443        *
1444        *  This function will insert a specified number of copies of
1445        *  the given data before the location specified by @a position.
1446        *
1447        *  Note that this kind of operation could be expensive for a
1448        *  %vector and if it is frequently used the user should
1449        *  consider using std::list.
1450        */
1451       void
1452       insert(iterator __position, size_type __n, const value_type& __x)
1453       { _M_fill_insert(__position, __n, __x); }
1454 #endif
1455 
1456 #if __cplusplus >= 201103L
1457       /**
1458        *  @brief  Inserts a range into the %vector.
1459        *  @param  __position  A const_iterator into the %vector.
1460        *  @param  __first  An input iterator.
1461        *  @param  __last   An input iterator.
1462        *  @return  An iterator that points to the inserted data.
1463        *
1464        *  This function will insert copies of the data in the range
1465        *  [__first,__last) into the %vector before the location specified
1466        *  by @a pos.
1467        *
1468        *  Note that this kind of operation could be expensive for a
1469        *  %vector and if it is frequently used the user should
1470        *  consider using std::list.
1471        */
1472       template<typename _InputIterator,
1473 	       typename = std::_RequireInputIter<_InputIterator>>
1474 	_GLIBCXX20_CONSTEXPR
1475 	iterator
1476 	insert(const_iterator __position, _InputIterator __first,
1477 	       _InputIterator __last)
1478 	{
1479 	  difference_type __offset = __position - cbegin();
1480 	  _M_insert_dispatch(begin() + __offset,
1481 			     __first, __last, __false_type());
1482 	  return begin() + __offset;
1483 	}
1484 #else
1485       /**
1486        *  @brief  Inserts a range into the %vector.
1487        *  @param  __position  An iterator into the %vector.
1488        *  @param  __first  An input iterator.
1489        *  @param  __last   An input iterator.
1490        *
1491        *  This function will insert copies of the data in the range
1492        *  [__first,__last) into the %vector before the location specified
1493        *  by @a pos.
1494        *
1495        *  Note that this kind of operation could be expensive for a
1496        *  %vector and if it is frequently used the user should
1497        *  consider using std::list.
1498        */
1499       template<typename _InputIterator>
1500 	void
1501 	insert(iterator __position, _InputIterator __first,
1502 	       _InputIterator __last)
1503 	{
1504 	  // Check whether it's an integral type.  If so, it's not an iterator.
1505 	  typedef typename std::__is_integer<_InputIterator>::__type _Integral;
1506 	  _M_insert_dispatch(__position, __first, __last, _Integral());
1507 	}
1508 #endif
1509 
1510       /**
1511        *  @brief  Remove element at given position.
1512        *  @param  __position  Iterator pointing to element to be erased.
1513        *  @return  An iterator pointing to the next element (or end()).
1514        *
1515        *  This function will erase the element at the given position and thus
1516        *  shorten the %vector by one.
1517        *
1518        *  Note This operation could be expensive and if it is
1519        *  frequently used the user should consider using std::list.
1520        *  The user is also cautioned that this function only erases
1521        *  the element, and that if the element is itself a pointer,
1522        *  the pointed-to memory is not touched in any way.  Managing
1523        *  the pointer is the user's responsibility.
1524        */
1525       _GLIBCXX20_CONSTEXPR
1526       iterator
1527 #if __cplusplus >= 201103L
1528       erase(const_iterator __position)
1529       { return _M_erase(begin() + (__position - cbegin())); }
1530 #else
1531       erase(iterator __position)
1532       { return _M_erase(__position); }
1533 #endif
1534 
1535       /**
1536        *  @brief  Remove a range of elements.
1537        *  @param  __first  Iterator pointing to the first element to be erased.
1538        *  @param  __last  Iterator pointing to one past the last element to be
1539        *                  erased.
1540        *  @return  An iterator pointing to the element pointed to by @a __last
1541        *           prior to erasing (or end()).
1542        *
1543        *  This function will erase the elements in the range
1544        *  [__first,__last) and shorten the %vector accordingly.
1545        *
1546        *  Note This operation could be expensive and if it is
1547        *  frequently used the user should consider using std::list.
1548        *  The user is also cautioned that this function only erases
1549        *  the elements, and that if the elements themselves are
1550        *  pointers, the pointed-to memory is not touched in any way.
1551        *  Managing the pointer is the user's responsibility.
1552        */
1553       _GLIBCXX20_CONSTEXPR
1554       iterator
1555 #if __cplusplus >= 201103L
1556       erase(const_iterator __first, const_iterator __last)
1557       {
1558 	const auto __beg = begin();
1559 	const auto __cbeg = cbegin();
1560 	return _M_erase(__beg + (__first - __cbeg), __beg + (__last - __cbeg));
1561       }
1562 #else
1563       erase(iterator __first, iterator __last)
1564       { return _M_erase(__first, __last); }
1565 #endif
1566 
1567       /**
1568        *  @brief  Swaps data with another %vector.
1569        *  @param  __x  A %vector of the same element and allocator types.
1570        *
1571        *  This exchanges the elements between two vectors in constant time.
1572        *  (Three pointers, so it should be quite fast.)
1573        *  Note that the global std::swap() function is specialized such that
1574        *  std::swap(v1,v2) will feed to this function.
1575        *
1576        *  Whether the allocators are swapped depends on the allocator traits.
1577        */
1578       _GLIBCXX20_CONSTEXPR
1579       void
1580       swap(vector& __x) _GLIBCXX_NOEXCEPT
1581       {
1582 #if __cplusplus >= 201103L
1583 	__glibcxx_assert(_Alloc_traits::propagate_on_container_swap::value
1584 			 || _M_get_Tp_allocator() == __x._M_get_Tp_allocator());
1585 #endif
1586 	this->_M_impl._M_swap_data(__x._M_impl);
1587 	_Alloc_traits::_S_on_swap(_M_get_Tp_allocator(),
1588 				  __x._M_get_Tp_allocator());
1589       }
1590 
1591       /**
1592        *  Erases all the elements.  Note that this function only erases the
1593        *  elements, and that if the elements themselves are pointers, the
1594        *  pointed-to memory is not touched in any way.  Managing the pointer is
1595        *  the user's responsibility.
1596        */
1597       _GLIBCXX20_CONSTEXPR
1598       void
1599       clear() _GLIBCXX_NOEXCEPT
1600       { _M_erase_at_end(this->_M_impl._M_start); }
1601 
1602     protected:
1603       /**
1604        *  Memory expansion handler.  Uses the member allocation function to
1605        *  obtain @a n bytes of memory, and then copies [first,last) into it.
1606        */
1607       template<typename _ForwardIterator>
1608 	_GLIBCXX20_CONSTEXPR
1609 	pointer
1610 	_M_allocate_and_copy(size_type __n,
1611 			     _ForwardIterator __first, _ForwardIterator __last)
1612 	{
1613 	  pointer __result = this->_M_allocate(__n);
1614 	  __try
1615 	    {
1616 	      std::__uninitialized_copy_a(__first, __last, __result,
1617 					  _M_get_Tp_allocator());
1618 	      return __result;
1619 	    }
1620 	  __catch(...)
1621 	    {
1622 	      _M_deallocate(__result, __n);
1623 	      __throw_exception_again;
1624 	    }
1625 	}
1626 
1627 
1628       // Internal constructor functions follow.
1629 
1630       // Called by the range constructor to implement [23.1.1]/9
1631 
1632 #if __cplusplus < 201103L
1633       // _GLIBCXX_RESOLVE_LIB_DEFECTS
1634       // 438. Ambiguity in the "do the right thing" clause
1635       template<typename _Integer>
1636 	void
1637 	_M_initialize_dispatch(_Integer __n, _Integer __value, __true_type)
1638 	{
1639 	  this->_M_impl._M_start = _M_allocate(_S_check_init_len(
1640 		static_cast<size_type>(__n), _M_get_Tp_allocator()));
1641 	  this->_M_impl._M_end_of_storage =
1642 	    this->_M_impl._M_start + static_cast<size_type>(__n);
1643 	  _M_fill_initialize(static_cast<size_type>(__n), __value);
1644 	}
1645 
1646       // Called by the range constructor to implement [23.1.1]/9
1647       template<typename _InputIterator>
1648 	void
1649 	_M_initialize_dispatch(_InputIterator __first, _InputIterator __last,
1650 			       __false_type)
1651 	{
1652 	  _M_range_initialize(__first, __last,
1653 			      std::__iterator_category(__first));
1654 	}
1655 #endif
1656 
1657       // Called by the second initialize_dispatch above
1658       template<typename _InputIterator>
1659 	_GLIBCXX20_CONSTEXPR
1660 	void
1661 	_M_range_initialize(_InputIterator __first, _InputIterator __last,
1662 			    std::input_iterator_tag)
1663 	{
1664 	  __try {
1665 	    for (; __first != __last; ++__first)
1666 #if __cplusplus >= 201103L
1667 	      emplace_back(*__first);
1668 #else
1669 	      push_back(*__first);
1670 #endif
1671 	  } __catch(...) {
1672 	    clear();
1673 	    __throw_exception_again;
1674 	  }
1675 	}
1676 
1677       // Called by the second initialize_dispatch above
1678       template<typename _ForwardIterator>
1679 	_GLIBCXX20_CONSTEXPR
1680 	void
1681 	_M_range_initialize(_ForwardIterator __first, _ForwardIterator __last,
1682 			    std::forward_iterator_tag)
1683 	{
1684 	  const size_type __n = std::distance(__first, __last);
1685 	  this->_M_impl._M_start
1686 	    = this->_M_allocate(_S_check_init_len(__n, _M_get_Tp_allocator()));
1687 	  this->_M_impl._M_end_of_storage = this->_M_impl._M_start + __n;
1688 	  this->_M_impl._M_finish =
1689 	    std::__uninitialized_copy_a(__first, __last,
1690 					this->_M_impl._M_start,
1691 					_M_get_Tp_allocator());
1692 	}
1693 
1694       // Called by the first initialize_dispatch above and by the
1695       // vector(n,value,a) constructor.
1696       _GLIBCXX20_CONSTEXPR
1697       void
1698       _M_fill_initialize(size_type __n, const value_type& __value)
1699       {
1700 	this->_M_impl._M_finish =
1701 	  std::__uninitialized_fill_n_a(this->_M_impl._M_start, __n, __value,
1702 					_M_get_Tp_allocator());
1703       }
1704 
1705 #if __cplusplus >= 201103L
1706       // Called by the vector(n) constructor.
1707       _GLIBCXX20_CONSTEXPR
1708       void
1709       _M_default_initialize(size_type __n)
1710       {
1711 	this->_M_impl._M_finish =
1712 	  std::__uninitialized_default_n_a(this->_M_impl._M_start, __n,
1713 					   _M_get_Tp_allocator());
1714       }
1715 #endif
1716 
1717       // Internal assign functions follow.  The *_aux functions do the actual
1718       // assignment work for the range versions.
1719 
1720       // Called by the range assign to implement [23.1.1]/9
1721 
1722       // _GLIBCXX_RESOLVE_LIB_DEFECTS
1723       // 438. Ambiguity in the "do the right thing" clause
1724       template<typename _Integer>
1725 	_GLIBCXX20_CONSTEXPR
1726 	void
1727 	_M_assign_dispatch(_Integer __n, _Integer __val, __true_type)
1728 	{ _M_fill_assign(__n, __val); }
1729 
1730       // Called by the range assign to implement [23.1.1]/9
1731       template<typename _InputIterator>
1732 	_GLIBCXX20_CONSTEXPR
1733 	void
1734 	_M_assign_dispatch(_InputIterator __first, _InputIterator __last,
1735 			   __false_type)
1736 	{ _M_assign_aux(__first, __last, std::__iterator_category(__first)); }
1737 
1738       // Called by the second assign_dispatch above
1739       template<typename _InputIterator>
1740 	_GLIBCXX20_CONSTEXPR
1741 	void
1742 	_M_assign_aux(_InputIterator __first, _InputIterator __last,
1743 		      std::input_iterator_tag);
1744 
1745       // Called by the second assign_dispatch above
1746       template<typename _ForwardIterator>
1747 	_GLIBCXX20_CONSTEXPR
1748 	void
1749 	_M_assign_aux(_ForwardIterator __first, _ForwardIterator __last,
1750 		      std::forward_iterator_tag);
1751 
1752       // Called by assign(n,t), and the range assign when it turns out
1753       // to be the same thing.
1754       _GLIBCXX20_CONSTEXPR
1755       void
1756       _M_fill_assign(size_type __n, const value_type& __val);
1757 
1758       // Internal insert functions follow.
1759 
1760       // Called by the range insert to implement [23.1.1]/9
1761 
1762       // _GLIBCXX_RESOLVE_LIB_DEFECTS
1763       // 438. Ambiguity in the "do the right thing" clause
1764       template<typename _Integer>
1765 	_GLIBCXX20_CONSTEXPR
1766 	void
1767 	_M_insert_dispatch(iterator __pos, _Integer __n, _Integer __val,
1768 			   __true_type)
1769 	{ _M_fill_insert(__pos, __n, __val); }
1770 
1771       // Called by the range insert to implement [23.1.1]/9
1772       template<typename _InputIterator>
1773 	_GLIBCXX20_CONSTEXPR
1774 	void
1775 	_M_insert_dispatch(iterator __pos, _InputIterator __first,
1776 			   _InputIterator __last, __false_type)
1777 	{
1778 	  _M_range_insert(__pos, __first, __last,
1779 			  std::__iterator_category(__first));
1780 	}
1781 
1782       // Called by the second insert_dispatch above
1783       template<typename _InputIterator>
1784 	_GLIBCXX20_CONSTEXPR
1785 	void
1786 	_M_range_insert(iterator __pos, _InputIterator __first,
1787 			_InputIterator __last, std::input_iterator_tag);
1788 
1789       // Called by the second insert_dispatch above
1790       template<typename _ForwardIterator>
1791 	_GLIBCXX20_CONSTEXPR
1792 	void
1793 	_M_range_insert(iterator __pos, _ForwardIterator __first,
1794 			_ForwardIterator __last, std::forward_iterator_tag);
1795 
1796       // Called by insert(p,n,x), and the range insert when it turns out to be
1797       // the same thing.
1798       _GLIBCXX20_CONSTEXPR
1799       void
1800       _M_fill_insert(iterator __pos, size_type __n, const value_type& __x);
1801 
1802 #if __cplusplus >= 201103L
1803       // Called by resize(n).
1804       _GLIBCXX20_CONSTEXPR
1805       void
1806       _M_default_append(size_type __n);
1807 
1808       _GLIBCXX20_CONSTEXPR
1809       bool
1810       _M_shrink_to_fit();
1811 #endif
1812 
1813 #if __cplusplus < 201103L
1814       // Called by insert(p,x)
1815       void
1816       _M_insert_aux(iterator __position, const value_type& __x);
1817 
1818       void
1819       _M_realloc_insert(iterator __position, const value_type& __x);
1820 #else
1821       // A value_type object constructed with _Alloc_traits::construct()
1822       // and destroyed with _Alloc_traits::destroy().
1823       struct _Temporary_value
1824       {
1825 	template<typename... _Args>
1826 	  _GLIBCXX20_CONSTEXPR explicit
1827 	  _Temporary_value(vector* __vec, _Args&&... __args) : _M_this(__vec)
1828 	  {
1829 	    _Alloc_traits::construct(_M_this->_M_impl, _M_ptr(),
1830 				     std::forward<_Args>(__args)...);
1831 	  }
1832 
1833 	_GLIBCXX20_CONSTEXPR
1834 	~_Temporary_value()
1835 	{ _Alloc_traits::destroy(_M_this->_M_impl, _M_ptr()); }
1836 
1837 	_GLIBCXX20_CONSTEXPR value_type&
1838 	_M_val() noexcept { return _M_storage._M_val; }
1839 
1840       private:
1841 	_GLIBCXX20_CONSTEXPR _Tp*
1842 	_M_ptr() noexcept { return std::__addressof(_M_storage._M_val); }
1843 
1844 	union _Storage
1845 	{
1846 	  constexpr _Storage() : _M_byte() { }
1847 	  _GLIBCXX20_CONSTEXPR ~_Storage() { }
1848 	  _Storage& operator=(const _Storage&) = delete;
1849 	  unsigned char _M_byte;
1850 	  _Tp _M_val;
1851 	};
1852 
1853 	vector*  _M_this;
1854 	_Storage _M_storage;
1855       };
1856 
1857       // Called by insert(p,x) and other functions when insertion needs to
1858       // reallocate or move existing elements. _Arg is either _Tp& or _Tp.
1859       template<typename _Arg>
1860 	_GLIBCXX20_CONSTEXPR
1861 	void
1862 	_M_insert_aux(iterator __position, _Arg&& __arg);
1863 
1864       template<typename... _Args>
1865 	_GLIBCXX20_CONSTEXPR
1866 	void
1867 	_M_realloc_insert(iterator __position, _Args&&... __args);
1868 
1869       // Either move-construct at the end, or forward to _M_insert_aux.
1870       _GLIBCXX20_CONSTEXPR
1871       iterator
1872       _M_insert_rval(const_iterator __position, value_type&& __v);
1873 
1874       // Try to emplace at the end, otherwise forward to _M_insert_aux.
1875       template<typename... _Args>
1876 	_GLIBCXX20_CONSTEXPR
1877 	iterator
1878 	_M_emplace_aux(const_iterator __position, _Args&&... __args);
1879 
1880       // Emplacing an rvalue of the correct type can use _M_insert_rval.
1881       _GLIBCXX20_CONSTEXPR
1882       iterator
1883       _M_emplace_aux(const_iterator __position, value_type&& __v)
1884       { return _M_insert_rval(__position, std::move(__v)); }
1885 #endif
1886 
1887       // Called by _M_fill_insert, _M_insert_aux etc.
1888       _GLIBCXX20_CONSTEXPR
1889       size_type
1890       _M_check_len(size_type __n, const char* __s) const
1891       {
1892 	if (max_size() - size() < __n)
1893 	  __throw_length_error(__N(__s));
1894 
1895 	const size_type __len = size() + (std::max)(size(), __n);
1896 	return (__len < size() || __len > max_size()) ? max_size() : __len;
1897       }
1898 
1899       // Called by constructors to check initial size.
1900       static _GLIBCXX20_CONSTEXPR size_type
1901       _S_check_init_len(size_type __n, const allocator_type& __a)
1902       {
1903 	if (__n > _S_max_size(_Tp_alloc_type(__a)))
1904 	  __throw_length_error(
1905 	      __N("cannot create std::vector larger than max_size()"));
1906 	return __n;
1907       }
1908 
1909       static _GLIBCXX20_CONSTEXPR size_type
1910       _S_max_size(const _Tp_alloc_type& __a) _GLIBCXX_NOEXCEPT
1911       {
1912 	// std::distance(begin(), end()) cannot be greater than PTRDIFF_MAX,
1913 	// and realistically we can't store more than PTRDIFF_MAX/sizeof(T)
1914 	// (even if std::allocator_traits::max_size says we can).
1915 	const size_t __diffmax
1916 	  = __gnu_cxx::__numeric_traits<ptrdiff_t>::__max / sizeof(_Tp);
1917 	const size_t __allocmax = _Alloc_traits::max_size(__a);
1918 	return (std::min)(__diffmax, __allocmax);
1919       }
1920 
1921       // Internal erase functions follow.
1922 
1923       // Called by erase(q1,q2), clear(), resize(), _M_fill_assign,
1924       // _M_assign_aux.
1925       _GLIBCXX20_CONSTEXPR
1926       void
1927       _M_erase_at_end(pointer __pos) _GLIBCXX_NOEXCEPT
1928       {
1929 	if (size_type __n = this->_M_impl._M_finish - __pos)
1930 	  {
1931 	    std::_Destroy(__pos, this->_M_impl._M_finish,
1932 			  _M_get_Tp_allocator());
1933 	    this->_M_impl._M_finish = __pos;
1934 	    _GLIBCXX_ASAN_ANNOTATE_SHRINK(__n);
1935 	  }
1936       }
1937 
1938       _GLIBCXX20_CONSTEXPR
1939       iterator
1940       _M_erase(iterator __position);
1941 
1942       _GLIBCXX20_CONSTEXPR
1943       iterator
1944       _M_erase(iterator __first, iterator __last);
1945 
1946 #if __cplusplus >= 201103L
1947     private:
1948       // Constant-time move assignment when source object's memory can be
1949       // moved, either because the source's allocator will move too
1950       // or because the allocators are equal.
1951       _GLIBCXX20_CONSTEXPR
1952       void
1953       _M_move_assign(vector&& __x, true_type) noexcept
1954       {
1955 	vector __tmp(get_allocator());
1956 	this->_M_impl._M_swap_data(__x._M_impl);
1957 	__tmp._M_impl._M_swap_data(__x._M_impl);
1958 	std::__alloc_on_move(_M_get_Tp_allocator(), __x._M_get_Tp_allocator());
1959       }
1960 
1961       // Do move assignment when it might not be possible to move source
1962       // object's memory, resulting in a linear-time operation.
1963       _GLIBCXX20_CONSTEXPR
1964       void
1965       _M_move_assign(vector&& __x, false_type)
1966       {
1967 	if (__x._M_get_Tp_allocator() == this->_M_get_Tp_allocator())
1968 	  _M_move_assign(std::move(__x), true_type());
1969 	else
1970 	  {
1971 	    // The rvalue's allocator cannot be moved and is not equal,
1972 	    // so we need to individually move each element.
1973 	    this->_M_assign_aux(std::make_move_iterator(__x.begin()),
1974 			        std::make_move_iterator(__x.end()),
1975 				std::random_access_iterator_tag());
1976 	    __x.clear();
1977 	  }
1978       }
1979 #endif
1980 
1981       template<typename _Up>
1982 	_GLIBCXX20_CONSTEXPR
1983 	_Up*
1984 	_M_data_ptr(_Up* __ptr) const _GLIBCXX_NOEXCEPT
1985 	{ return __ptr; }
1986 
1987 #if __cplusplus >= 201103L
1988       template<typename _Ptr>
1989 	_GLIBCXX20_CONSTEXPR
1990 	typename std::pointer_traits<_Ptr>::element_type*
1991 	_M_data_ptr(_Ptr __ptr) const
1992 	{ return empty() ? nullptr : std::__to_address(__ptr); }
1993 #else
1994       template<typename _Up>
1995 	_Up*
1996 	_M_data_ptr(_Up* __ptr) _GLIBCXX_NOEXCEPT
1997 	{ return __ptr; }
1998 
1999       template<typename _Ptr>
2000 	value_type*
2001 	_M_data_ptr(_Ptr __ptr)
2002 	{ return empty() ? (value_type*)0 : __ptr.operator->(); }
2003 
2004       template<typename _Ptr>
2005 	const value_type*
2006 	_M_data_ptr(_Ptr __ptr) const
2007 	{ return empty() ? (const value_type*)0 : __ptr.operator->(); }
2008 #endif
2009     };
2010 
2011 #if __cpp_deduction_guides >= 201606
2012   template<typename _InputIterator, typename _ValT
2013 	     = typename iterator_traits<_InputIterator>::value_type,
2014 	   typename _Allocator = allocator<_ValT>,
2015 	   typename = _RequireInputIter<_InputIterator>,
2016 	   typename = _RequireAllocator<_Allocator>>
2017     vector(_InputIterator, _InputIterator, _Allocator = _Allocator())
2018       -> vector<_ValT, _Allocator>;
2019 #endif
2020 
2021   /**
2022    *  @brief  Vector equality comparison.
2023    *  @param  __x  A %vector.
2024    *  @param  __y  A %vector of the same type as @a __x.
2025    *  @return  True iff the size and elements of the vectors are equal.
2026    *
2027    *  This is an equivalence relation.  It is linear in the size of the
2028    *  vectors.  Vectors are considered equivalent if their sizes are equal,
2029    *  and if corresponding elements compare equal.
2030   */
2031   template<typename _Tp, typename _Alloc>
2032     _GLIBCXX20_CONSTEXPR
2033     inline bool
2034     operator==(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
2035     { return (__x.size() == __y.size()
2036 	      && std::equal(__x.begin(), __x.end(), __y.begin())); }
2037 
2038 #if __cpp_lib_three_way_comparison
2039   /**
2040    *  @brief  Vector ordering relation.
2041    *  @param  __x  A `vector`.
2042    *  @param  __y  A `vector` of the same type as `__x`.
2043    *  @return  A value indicating whether `__x` is less than, equal to,
2044    *           greater than, or incomparable with `__y`.
2045    *
2046    *  See `std::lexicographical_compare_three_way()` for how the determination
2047    *  is made. This operator is used to synthesize relational operators like
2048    *  `<` and `>=` etc.
2049   */
2050   template<typename _Tp, typename _Alloc>
2051     _GLIBCXX20_CONSTEXPR
2052     inline __detail::__synth3way_t<_Tp>
2053     operator<=>(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
2054     {
2055       return std::lexicographical_compare_three_way(__x.begin(), __x.end(),
2056 						    __y.begin(), __y.end(),
2057 						    __detail::__synth3way);
2058     }
2059 #else
2060   /**
2061    *  @brief  Vector ordering relation.
2062    *  @param  __x  A %vector.
2063    *  @param  __y  A %vector of the same type as @a __x.
2064    *  @return  True iff @a __x is lexicographically less than @a __y.
2065    *
2066    *  This is a total ordering relation.  It is linear in the size of the
2067    *  vectors.  The elements must be comparable with @c <.
2068    *
2069    *  See std::lexicographical_compare() for how the determination is made.
2070   */
2071   template<typename _Tp, typename _Alloc>
2072     inline bool
2073     operator<(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
2074     { return std::lexicographical_compare(__x.begin(), __x.end(),
2075 					  __y.begin(), __y.end()); }
2076 
2077   /// Based on operator==
2078   template<typename _Tp, typename _Alloc>
2079     inline bool
2080     operator!=(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
2081     { return !(__x == __y); }
2082 
2083   /// Based on operator<
2084   template<typename _Tp, typename _Alloc>
2085     inline bool
2086     operator>(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
2087     { return __y < __x; }
2088 
2089   /// Based on operator<
2090   template<typename _Tp, typename _Alloc>
2091     inline bool
2092     operator<=(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
2093     { return !(__y < __x); }
2094 
2095   /// Based on operator<
2096   template<typename _Tp, typename _Alloc>
2097     inline bool
2098     operator>=(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
2099     { return !(__x < __y); }
2100 #endif // three-way comparison
2101 
2102   /// See std::vector::swap().
2103   template<typename _Tp, typename _Alloc>
2104     _GLIBCXX20_CONSTEXPR
2105     inline void
2106     swap(vector<_Tp, _Alloc>& __x, vector<_Tp, _Alloc>& __y)
2107     _GLIBCXX_NOEXCEPT_IF(noexcept(__x.swap(__y)))
2108     { __x.swap(__y); }
2109 
2110 _GLIBCXX_END_NAMESPACE_CONTAINER
2111 
2112 #if __cplusplus >= 201703L
2113   namespace __detail::__variant
2114   {
2115     template<typename> struct _Never_valueless_alt; // see <variant>
2116 
2117     // Provide the strong exception-safety guarantee when emplacing a
2118     // vector into a variant, but only if move assignment cannot throw.
2119     template<typename _Tp, typename _Alloc>
2120       struct _Never_valueless_alt<_GLIBCXX_STD_C::vector<_Tp, _Alloc>>
2121       : std::is_nothrow_move_assignable<_GLIBCXX_STD_C::vector<_Tp, _Alloc>>
2122       { };
2123   }  // namespace __detail::__variant
2124 #endif // C++17
2125 
2126 _GLIBCXX_END_NAMESPACE_VERSION
2127 } // namespace std
2128 
2129 #endif /* _STL_VECTOR_H */
2130