libstdc++: scoped_allocator Source File

libstdc++

scoped_allocator
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1// <scoped_allocator> -*- C++ -*-
2
3// Copyright (C) 2011-2026 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25/** @file include/scoped_allocator
26 * This is a Standard C++ Library header.
27 */
28
29#ifndef _SCOPED_ALLOCATOR
30#define _SCOPED_ALLOCATOR 1
31
32#ifdef _GLIBCXX_SYSHDR
33#pragma GCC system_header
34#endif
35
36#if __cplusplus < 201103L
37# include <bits/c++0x_warning.h>
38#else
39
40#include <tuple>
41#include <bits/alloc_traits.h>
42#include <bits/stl_pair.h>
43#include <bits/uses_allocator.h>
44#if __cplusplus > 201703L
45# include <bits/uses_allocator_args.h>
46#endif
47
48#define __glibcxx_want_allocator_traits_is_always_equal
49#include <bits/version.h>
50
51namespace std _GLIBCXX_VISIBILITY(default)
52{
53_GLIBCXX_BEGIN_NAMESPACE_VERSION
54
55 /**
56 * @addtogroup allocators
57 * @{
58 */
59
60 template<typename _OuterAlloc, typename... _InnerAllocs>
61 class scoped_allocator_adaptor;
62
63 /// @cond undocumented
64
65 template<typename _Alloc>
66 using __outer_allocator_t
67 = decltype(std::declval<_Alloc>().outer_allocator());
68
69 template<typename _Alloc, typename = void>
70 struct __outermost_type
71 {
72 using type = _Alloc;
73 static type& _S_outermost(_Alloc& __a) noexcept { return __a; }
74 };
75
76 template<typename _Alloc>
77 struct __outermost_type<_Alloc, __void_t<__outer_allocator_t<_Alloc>>>
78 : __outermost_type<
79 typename remove_reference<__outer_allocator_t<_Alloc>>::type
80 >
81 {
82 using __base = __outermost_type<
83 typename remove_reference<__outer_allocator_t<_Alloc>>::type
84 >;
85
86 static typename __base::type&
87 _S_outermost(_Alloc& __a) noexcept
88 { return __base::_S_outermost(__a.outer_allocator()); }
89 };
90
91 // Implementation of the OUTERMOST pseudofunction
92 template<typename _Alloc>
93 inline typename __outermost_type<_Alloc>::type&
94 __outermost(_Alloc& __a)
95 { return __outermost_type<_Alloc>::_S_outermost(__a); }
96
97 template<typename...>
98 struct __inner_type_impl;
99
100 template<typename _Outer>
101 struct __inner_type_impl<_Outer>
102 {
103 typedef scoped_allocator_adaptor<_Outer> __type;
104
105 __inner_type_impl() = default;
106 __inner_type_impl(const __inner_type_impl&) = default;
107 __inner_type_impl(__inner_type_impl&&) = default;
108 __inner_type_impl& operator=(const __inner_type_impl&) = default;
109 __inner_type_impl& operator=(__inner_type_impl&&) = default;
110
111 template<typename _Alloc>
112 __inner_type_impl(const __inner_type_impl<_Alloc>&) noexcept
113 { }
114
115 template<typename _Alloc>
116 __inner_type_impl(__inner_type_impl<_Alloc>&&) noexcept
117 { }
118
119 __type&
120 _M_get(__type* __p) noexcept { return *__p; }
121
122 const __type&
123 _M_get(const __type* __p) const noexcept { return *__p; }
124
125 tuple<>
126 _M_tie() const noexcept { return tuple<>(); }
127
128 bool
129 operator==(const __inner_type_impl&) const noexcept
130 { return true; }
131 };
132
133 template<typename _Outer, typename _InnerHead, typename... _InnerTail>
134 struct __inner_type_impl<_Outer, _InnerHead, _InnerTail...>
135 {
136 typedef scoped_allocator_adaptor<_InnerHead, _InnerTail...> __type;
137
138 __inner_type_impl() = default;
139 __inner_type_impl(const __inner_type_impl&) = default;
140 __inner_type_impl(__inner_type_impl&&) = default;
141 __inner_type_impl& operator=(const __inner_type_impl&) = default;
142 __inner_type_impl& operator=(__inner_type_impl&&) = default;
143
144 template<typename... _Allocs>
145 __inner_type_impl(const __inner_type_impl<_Allocs...>& __other) noexcept
146 : _M_inner(__other._M_inner) { }
147
148 template<typename... _Allocs>
149 __inner_type_impl(__inner_type_impl<_Allocs...>&& __other) noexcept
150 : _M_inner(std::move(__other._M_inner)) { }
151
152 template<typename... _Args>
153 explicit
154 __inner_type_impl(_Args&&... __args) noexcept
155 : _M_inner(std::forward<_Args>(__args)...) { }
156
157 __type&
158 _M_get(void*) noexcept { return _M_inner; }
159
160 const __type&
161 _M_get(const void*) const noexcept { return _M_inner; }
162
163 tuple<const _InnerHead&, const _InnerTail&...>
164 _M_tie() const noexcept
165 { return _M_inner._M_tie(); }
166
167 bool
168 operator==(const __inner_type_impl& __other) const noexcept
169 { return _M_inner == __other._M_inner; }
170
171 private:
172 template<typename...> friend struct __inner_type_impl;
173 template<typename, typename...> friend class scoped_allocator_adaptor;
174
175 __type _M_inner;
176 };
177
178 /// @endcond
179
180 /// An adaptor to recursively pass an allocator to the objects it constructs
181 template<typename _OuterAlloc, typename... _InnerAllocs>
182 class scoped_allocator_adaptor
183 : public _OuterAlloc
184 {
185 typedef allocator_traits<_OuterAlloc> __traits;
186
187 typedef __inner_type_impl<_OuterAlloc, _InnerAllocs...> __inner_type;
188 __inner_type _M_inner;
189
190 template<typename _Outer, typename... _Inner>
191 friend class scoped_allocator_adaptor;
192
193 template<typename...>
194 friend struct __inner_type_impl;
195
196 tuple<const _OuterAlloc&, const _InnerAllocs&...>
197 _M_tie() const noexcept
198 { return std::tuple_cat(std::tie(outer_allocator()), _M_inner._M_tie()); }
199
200 template<typename _Alloc>
201 using __outermost_alloc_traits
202 = allocator_traits<typename __outermost_type<_Alloc>::type>;
203
204#if ! __glibcxx_make_obj_using_allocator
205 template<typename _Tp, typename... _Args>
206 void
207 _M_construct(__uses_alloc0, _Tp* __p, _Args&&... __args)
208 {
209 typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
210 _O_traits::construct(__outermost(*this), __p,
211 std::forward<_Args>(__args)...);
212 }
213
214 typedef __uses_alloc1<typename __inner_type::__type> __uses_alloc1_;
215 typedef __uses_alloc2<typename __inner_type::__type> __uses_alloc2_;
216
217 template<typename _Tp, typename... _Args>
218 void
219 _M_construct(__uses_alloc1_, _Tp* __p, _Args&&... __args)
220 {
221 typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
222 _O_traits::construct(__outermost(*this), __p,
223 allocator_arg, inner_allocator(),
224 std::forward<_Args>(__args)...);
225 }
226
227 template<typename _Tp, typename... _Args>
228 void
229 _M_construct(__uses_alloc2_, _Tp* __p, _Args&&... __args)
230 {
231 typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
232 _O_traits::construct(__outermost(*this), __p,
233 std::forward<_Args>(__args)...,
234 inner_allocator());
235 }
236#endif // ! make_obj_using_allocator
237
238 template<typename _Alloc>
239 static _Alloc
240 _S_select_on_copy(const _Alloc& __a)
241 {
242 typedef allocator_traits<_Alloc> __a_traits;
243 return __a_traits::select_on_container_copy_construction(__a);
244 }
245
246 template<std::size_t... _Indices>
247 scoped_allocator_adaptor(tuple<const _OuterAlloc&,
248 const _InnerAllocs&...> __refs,
249 _Index_tuple<_Indices...>)
250 : _OuterAlloc(_S_select_on_copy(std::get<0>(__refs))),
251 _M_inner(_S_select_on_copy(std::get<_Indices+1>(__refs))...)
252 { }
253
254 // Used to constrain constructors to disallow invalid conversions.
255 template<typename _Alloc>
256 using _Constructible = typename enable_if<
257 is_constructible<_OuterAlloc, _Alloc>::value
258 >::type;
259
260 // _GLIBCXX_RESOLVE_LIB_DEFECTS
261 // 2975. Missing case for pair construction in scoped [...] allocators
262 template<typename _Tp>
263 struct __not_pair { using type = void; };
264
265 template<typename _Tp, typename _Up>
266 struct __not_pair<pair<_Tp, _Up>> { };
267
268 public:
269 typedef _OuterAlloc outer_allocator_type;
270 typedef typename __inner_type::__type inner_allocator_type;
271
272 typedef typename __traits::value_type value_type;
273 typedef typename __traits::size_type size_type;
274 typedef typename __traits::difference_type difference_type;
275 typedef typename __traits::pointer pointer;
276 typedef typename __traits::const_pointer const_pointer;
277 typedef typename __traits::void_pointer void_pointer;
278 typedef typename __traits::const_void_pointer const_void_pointer;
279
280 typedef typename __or_<
281 typename __traits::propagate_on_container_copy_assignment,
282 typename allocator_traits<_InnerAllocs>::
283 propagate_on_container_copy_assignment...>::type
284 propagate_on_container_copy_assignment;
285
286 typedef typename __or_<
287 typename __traits::propagate_on_container_move_assignment,
288 typename allocator_traits<_InnerAllocs>::
289 propagate_on_container_move_assignment...>::type
290 propagate_on_container_move_assignment;
291
292 typedef typename __or_<
293 typename __traits::propagate_on_container_swap,
294 typename allocator_traits<_InnerAllocs>::
295 propagate_on_container_swap...>::type
296 propagate_on_container_swap;
297
298 typedef typename __and_<
299 typename __traits::is_always_equal,
300 typename allocator_traits<_InnerAllocs>::is_always_equal...>::type
301 is_always_equal;
302
303 template <class _Tp>
304 struct rebind
305 {
306 typedef scoped_allocator_adaptor<
307 typename __traits::template rebind_alloc<_Tp>,
308 _InnerAllocs...> other;
309 };
310
311 scoped_allocator_adaptor() : _OuterAlloc(), _M_inner() { }
312
313 template<typename _Outer2, typename = _Constructible<_Outer2>>
314 scoped_allocator_adaptor(_Outer2&& __outer,
315 const _InnerAllocs&... __inner) noexcept
316 : _OuterAlloc(std::forward<_Outer2>(__outer)),
317 _M_inner(__inner...)
318 { }
319
320 scoped_allocator_adaptor(const scoped_allocator_adaptor& __other) noexcept
321 : _OuterAlloc(__other.outer_allocator()),
322 _M_inner(__other._M_inner)
323 { }
324
325 scoped_allocator_adaptor(scoped_allocator_adaptor&& __other) noexcept
326 : _OuterAlloc(std::move(__other.outer_allocator())),
327 _M_inner(std::move(__other._M_inner))
328 { }
329
330 template<typename _Outer2, typename = _Constructible<const _Outer2&>>
331 scoped_allocator_adaptor(
332 const scoped_allocator_adaptor<_Outer2, _InnerAllocs...>& __other
333 ) noexcept
334 : _OuterAlloc(__other.outer_allocator()),
335 _M_inner(__other._M_inner)
336 { }
337
338 template<typename _Outer2, typename = _Constructible<_Outer2>>
339 scoped_allocator_adaptor(
340 scoped_allocator_adaptor<_Outer2, _InnerAllocs...>&& __other) noexcept
341 : _OuterAlloc(std::move(__other.outer_allocator())),
342 _M_inner(std::move(__other._M_inner))
343 { }
344
345 scoped_allocator_adaptor&
346 operator=(const scoped_allocator_adaptor&) = default;
347
348 scoped_allocator_adaptor&
349 operator=(scoped_allocator_adaptor&&) = default;
350
351 inner_allocator_type&
352 inner_allocator() noexcept
353 { return _M_inner._M_get(this); }
354
355 const inner_allocator_type&
356 inner_allocator() const noexcept
357 { return _M_inner._M_get(this); }
358
359 outer_allocator_type&
360 outer_allocator() noexcept
361 { return static_cast<_OuterAlloc&>(*this); }
362
363 const outer_allocator_type&
364 outer_allocator() const noexcept
365 { return static_cast<const _OuterAlloc&>(*this); }
366
367 _GLIBCXX_NODISCARD pointer
368 allocate(size_type __n)
369 { return __traits::allocate(outer_allocator(), __n); }
370
371 _GLIBCXX_NODISCARD pointer
372 allocate(size_type __n, const_void_pointer __hint)
373 { return __traits::allocate(outer_allocator(), __n, __hint); }
374
375 void deallocate(pointer __p, size_type __n) noexcept
376 { return __traits::deallocate(outer_allocator(), __p, __n); }
377
378 size_type max_size() const
379 { return __traits::max_size(outer_allocator()); }
380
381#if ! __glibcxx_make_obj_using_allocator
382 template<typename _Tp, typename... _Args>
383 typename __not_pair<_Tp>::type
384 construct(_Tp* __p, _Args&&... __args)
385 {
386 auto& __inner = inner_allocator();
387 auto __use_tag
388 = std::__use_alloc<_Tp, inner_allocator_type, _Args...>(__inner);
389 _M_construct(__use_tag, __p, std::forward<_Args>(__args)...);
390 }
391
392 template<typename _T1, typename _T2, typename... _Args1,
393 typename... _Args2>
394 void
395 construct(pair<_T1, _T2>* __p, piecewise_construct_t,
396 tuple<_Args1...> __x, tuple<_Args2...> __y)
397 {
398 // _GLIBCXX_RESOLVE_LIB_DEFECTS
399 // 2203. wrong argument types for piecewise construction
400 auto& __inner = inner_allocator();
401 auto __x_use_tag
402 = std::__use_alloc<_T1, inner_allocator_type, _Args1...>(__inner);
403 auto __y_use_tag
404 = std::__use_alloc<_T2, inner_allocator_type, _Args2...>(__inner);
405 typename _Build_index_tuple<sizeof...(_Args1)>::__type __x_indices;
406 typename _Build_index_tuple<sizeof...(_Args2)>::__type __y_indices;
407 typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
408 _O_traits::construct(__outermost(*this), __p, piecewise_construct,
409 _M_construct_p(__x_use_tag, __x_indices, __x),
410 _M_construct_p(__y_use_tag, __y_indices, __y));
411 }
412
413 template<typename _T1, typename _T2>
414 void
415 construct(pair<_T1, _T2>* __p)
416 { construct(__p, piecewise_construct, tuple<>(), tuple<>()); }
417
418 template<typename _T1, typename _T2, typename _Up, typename _Vp>
419 void
420 construct(pair<_T1, _T2>* __p, _Up&& __u, _Vp&& __v)
421 {
422 construct(__p, piecewise_construct,
423 std::forward_as_tuple(std::forward<_Up>(__u)),
424 std::forward_as_tuple(std::forward<_Vp>(__v)));
425 }
426
427 template<typename _T1, typename _T2, typename _Up, typename _Vp>
428 void
429 construct(pair<_T1, _T2>* __p, const pair<_Up, _Vp>& __x)
430 {
431 construct(__p, piecewise_construct,
432 std::forward_as_tuple(__x.first),
433 std::forward_as_tuple(__x.second));
434 }
435
436 template<typename _T1, typename _T2, typename _Up, typename _Vp>
437 void
438 construct(pair<_T1, _T2>* __p, pair<_Up, _Vp>&& __x)
439 {
440 construct(__p, piecewise_construct,
441 std::forward_as_tuple(std::forward<_Up>(__x.first)),
442 std::forward_as_tuple(std::forward<_Vp>(__x.second)));
443 }
444#else // make_obj_using_allocator
445 template<typename _Tp, typename... _Args>
446 __attribute__((__nonnull__))
447 void
448 construct(_Tp* __p, _Args&&... __args)
449 {
450 typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
451 std::apply([__p, this](auto&&... __newargs) {
452 _O_traits::construct(__outermost(*this), __p,
453 std::forward<decltype(__newargs)>(__newargs)...);
454 },
455 uses_allocator_construction_args<_Tp>(inner_allocator(),
456 std::forward<_Args>(__args)...));
457 }
458#endif
459
460 template<typename _Tp>
461 void destroy(_Tp* __p)
462 {
463 typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
464 _O_traits::destroy(__outermost(*this), __p);
465 }
466
467 scoped_allocator_adaptor
468 select_on_container_copy_construction() const
469 {
470 typedef typename _Build_index_tuple<sizeof...(_InnerAllocs)>::__type
471 _Indices;
472 return scoped_allocator_adaptor(_M_tie(), _Indices());
473 }
474
475 template <typename _OutA1, typename _OutA2, typename... _InA>
476 friend bool
477 operator==(const scoped_allocator_adaptor<_OutA1, _InA...>& __a,
478 const scoped_allocator_adaptor<_OutA2, _InA...>& __b) noexcept;
479
480 private:
481#if ! __glibcxx_make_obj_using_allocator
482 template<typename _Ind, typename... _Args>
483 tuple<_Args&&...>
484 _M_construct_p(__uses_alloc0, _Ind, tuple<_Args...>& __t)
485 { return std::move(__t); }
486
487 template<size_t... _Ind, typename... _Args>
488 tuple<allocator_arg_t, inner_allocator_type&, _Args&&...>
489 _M_construct_p(__uses_alloc1_, _Index_tuple<_Ind...>,
490 tuple<_Args...>& __t)
491 {
492 return { allocator_arg, inner_allocator(),
493 std::get<_Ind>(std::move(__t))...
494 };
495 }
496
497 template<size_t... _Ind, typename... _Args>
498 tuple<_Args&&..., inner_allocator_type&>
499 _M_construct_p(__uses_alloc2_, _Index_tuple<_Ind...>,
500 tuple<_Args...>& __t)
501 {
502 return { std::get<_Ind>(std::move(__t))..., inner_allocator() };
503 }
504#endif // ! make_obj_using_allocator
505 };
506
507 /// @related std::scoped_allocator_adaptor
508 template <typename _OutA1, typename _OutA2, typename... _InA>
509 inline bool
510 operator==(const scoped_allocator_adaptor<_OutA1, _InA...>& __a,
511 const scoped_allocator_adaptor<_OutA2, _InA...>& __b) noexcept
512 {
513 return __a.outer_allocator() == __b.outer_allocator()
514 && __a._M_inner == __b._M_inner;
515 }
516
517#if __cpp_impl_three_way_comparison < 201907L
518 /// @related std::scoped_allocator_adaptor
519 template <typename _OutA1, typename _OutA2, typename... _InA>
520 inline bool
521 operator!=(const scoped_allocator_adaptor<_OutA1, _InA...>& __a,
522 const scoped_allocator_adaptor<_OutA2, _InA...>& __b) noexcept
523 { return !(__a == __b); }
524#endif
525
526 /// @}
527
528_GLIBCXX_END_NAMESPACE_VERSION
529} // namespace
530
531#endif // C++11
532
533#endif // _SCOPED_ALLOCATOR
tuple
c++0x_warning.h
stl_pair.h
version.h
uses_allocator_args.h
std::tuple_cat
constexpr auto tuple_cat(_Tpls &&... __tpls) -> typename __tuple_cat_result< _Tpls... >::__type
Create a tuple containing all elements from multiple tuple-like objects.
Definition tuple:2829
std::declval
auto declval() noexcept -> decltype(__declval< _Tp >(0))
Definition type_traits:2741
std::forward_as_tuple
constexpr tuple< _Elements &&... > forward_as_tuple(_Elements &&... __args) noexcept
Create a tuple of lvalue or rvalue references to the arguments.
Definition tuple:2705
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition move.h:138
std::piecewise_construct
constexpr piecewise_construct_t piecewise_construct
Tag for piecewise construction of std::pair objects.
Definition stl_pair.h:82
std::tie
constexpr tuple< _Elements &... > tie(_Elements &... __args) noexcept
Return a tuple of lvalue references bound to the arguments.
Definition tuple:2843
std::forward
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition move.h:72
std
ISO C++ entities toplevel namespace is std.
__gnu_debug::__base
constexpr _Iterator __base(_Iterator __it)
Definition helper_functions.h:339
std::scoped_allocator_adaptor
An adaptor to recursively pass an allocator to the objects it constructs.
Definition scoped_allocator:184
std::tuple
Primary class template, tuple.
Definition tuple:799
std::enable_if
Define a member typedef type only if a boolean constant is true.
Definition type_traits:137
std::is_constructible
is_constructible
Definition type_traits:1265
std::allocator_traits
Uniform interface to all allocator types.
Definition bits/alloc_traits.h:257
std::allocator_traits< _OuterAlloc >::propagate_on_container_move_assignment
__detected_or_t< false_type, __pocma, _OuterAlloc > propagate_on_container_move_assignment
Definition bits/alloc_traits.h:356
std::allocator_traits< _OuterAlloc >::void_pointer
typename _Ptr< __v_pointer, void >::type void_pointer
Definition bits/alloc_traits.h:316
std::allocator_traits< _OuterAlloc >::pointer
__detected_or_t< value_type *, __pointer, _OuterAlloc > pointer
Definition bits/alloc_traits.h:268
std::allocator_traits< _OuterAlloc >::allocate
static constexpr pointer allocate(_OuterAlloc &__a, size_type __n)
Definition bits/alloc_traits.h:387
std::allocator_traits< _OuterAlloc >::size_type
typename _Size< _OuterAlloc, difference_type >::type size_type
Definition bits/alloc_traits.h:340
std::allocator_traits< _OuterAlloc >::const_void_pointer
typename _Ptr< __cv_pointer, const void >::type const_void_pointer
Definition bits/alloc_traits.h:324
std::allocator_traits< _OuterAlloc >::difference_type
typename _Diff< _OuterAlloc, pointer >::type difference_type
Definition bits/alloc_traits.h:332
std::allocator_traits< _OuterAlloc >::const_pointer
typename _Ptr< __c_pointer, const value_type >::type const_pointer
Definition bits/alloc_traits.h:308
std::allocator_traits< _OuterAlloc >::value_type
_OuterAlloc::value_type value_type
Definition bits/alloc_traits.h:261
std::allocator_traits< _OuterAlloc >::deallocate
static constexpr void deallocate(_OuterAlloc &__a, pointer __p, size_type __n)
Definition bits/alloc_traits.h:442
std::allocator_traits< _OuterAlloc >::is_always_equal
typename __detected_or_t< is_empty< _OuterAlloc >, __equal, _OuterAlloc >::type is_always_equal
Definition bits/alloc_traits.h:372
std::allocator_traits< _OuterAlloc >::max_size
static constexpr size_type max_size(const _OuterAlloc &__a) noexcept
Definition bits/alloc_traits.h:500
std::allocator_traits< _OuterAlloc >::propagate_on_container_copy_assignment
__detected_or_t< false_type, __pocca, _OuterAlloc > propagate_on_container_copy_assignment
Definition bits/alloc_traits.h:348
std::allocator_traits< _OuterAlloc >::propagate_on_container_swap
__detected_or_t< false_type, __pocs, _OuterAlloc > propagate_on_container_swap
Definition bits/alloc_traits.h:364
std::pair
Struct holding two objects (or references) of arbitrary type.
Definition stl_pair.h:307
std::pair::first
_T1 first
The first member.
Definition stl_pair.h:311
std::pair::second
_T2 second
The second member.
Definition stl_pair.h:312
std::piecewise_construct_t
Tag type for piecewise construction of std::pair objects.
Definition stl_pair.h:79
alloc_traits.h