libstdc++
scoped_allocator
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1// <scoped_allocator> -*- C++ -*-
2
3// Copyright (C) 2011-2024 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#pragma GCC system_header
33
34#if __cplusplus < 201103L
35# include <bits/c++0x_warning.h>
36#else
37
38#include <tuple>
39#include <bits/alloc_traits.h>
40#include <bits/stl_pair.h>
41#include <bits/uses_allocator.h>
42#if __cplusplus > 201703L
43# include <bits/uses_allocator_args.h>
44#endif
45
46namespace std _GLIBCXX_VISIBILITY(default)
47{
48_GLIBCXX_BEGIN_NAMESPACE_VERSION
49
50 /**
51 * @addtogroup allocators
52 * @{
53 */
54
55 template<typename _OuterAlloc, typename... _InnerAllocs>
56 class scoped_allocator_adaptor;
57
58 /// @cond undocumented
59
60 template<typename _Alloc>
61 using __outer_allocator_t
62 = decltype(std::declval<_Alloc>().outer_allocator());
63
64 template<typename _Alloc, typename = void>
65 struct __outermost_type
66 {
67 using type = _Alloc;
68 static type& _S_outermost(_Alloc& __a) noexcept { return __a; }
69 };
70
71 template<typename _Alloc>
72 struct __outermost_type<_Alloc, __void_t<__outer_allocator_t<_Alloc>>>
73 : __outermost_type<
74 typename remove_reference<__outer_allocator_t<_Alloc>>::type
75 >
76 {
77 using __base = __outermost_type<
78 typename remove_reference<__outer_allocator_t<_Alloc>>::type
79 >;
80
81 static typename __base::type&
82 _S_outermost(_Alloc& __a) noexcept
83 { return __base::_S_outermost(__a.outer_allocator()); }
84 };
85
86 // Implementation of the OUTERMOST pseudofunction
87 template<typename _Alloc>
88 inline typename __outermost_type<_Alloc>::type&
89 __outermost(_Alloc& __a)
90 { return __outermost_type<_Alloc>::_S_outermost(__a); }
91
92 template<typename...>
93 struct __inner_type_impl;
94
95 template<typename _Outer>
96 struct __inner_type_impl<_Outer>
97 {
98 typedef scoped_allocator_adaptor<_Outer> __type;
99
100 __inner_type_impl() = default;
101 __inner_type_impl(const __inner_type_impl&) = default;
102 __inner_type_impl(__inner_type_impl&&) = default;
103 __inner_type_impl& operator=(const __inner_type_impl&) = default;
104 __inner_type_impl& operator=(__inner_type_impl&&) = default;
105
106 template<typename _Alloc>
107 __inner_type_impl(const __inner_type_impl<_Alloc>&) noexcept
108 { }
109
110 template<typename _Alloc>
111 __inner_type_impl(__inner_type_impl<_Alloc>&&) noexcept
112 { }
113
114 __type&
115 _M_get(__type* __p) noexcept { return *__p; }
116
117 const __type&
118 _M_get(const __type* __p) const noexcept { return *__p; }
119
120 tuple<>
121 _M_tie() const noexcept { return tuple<>(); }
122
123 bool
124 operator==(const __inner_type_impl&) const noexcept
125 { return true; }
126 };
127
128 template<typename _Outer, typename _InnerHead, typename... _InnerTail>
129 struct __inner_type_impl<_Outer, _InnerHead, _InnerTail...>
130 {
131 typedef scoped_allocator_adaptor<_InnerHead, _InnerTail...> __type;
132
133 __inner_type_impl() = default;
134 __inner_type_impl(const __inner_type_impl&) = default;
135 __inner_type_impl(__inner_type_impl&&) = default;
136 __inner_type_impl& operator=(const __inner_type_impl&) = default;
137 __inner_type_impl& operator=(__inner_type_impl&&) = default;
138
139 template<typename... _Allocs>
140 __inner_type_impl(const __inner_type_impl<_Allocs...>& __other) noexcept
141 : _M_inner(__other._M_inner) { }
142
143 template<typename... _Allocs>
144 __inner_type_impl(__inner_type_impl<_Allocs...>&& __other) noexcept
145 : _M_inner(std::move(__other._M_inner)) { }
146
147 template<typename... _Args>
148 explicit
149 __inner_type_impl(_Args&&... __args) noexcept
150 : _M_inner(std::forward<_Args>(__args)...) { }
151
152 __type&
153 _M_get(void*) noexcept { return _M_inner; }
154
155 const __type&
156 _M_get(const void*) const noexcept { return _M_inner; }
157
158 tuple<const _InnerHead&, const _InnerTail&...>
159 _M_tie() const noexcept
160 { return _M_inner._M_tie(); }
161
162 bool
163 operator==(const __inner_type_impl& __other) const noexcept
164 { return _M_inner == __other._M_inner; }
165
166 private:
167 template<typename...> friend struct __inner_type_impl;
168 template<typename, typename...> friend class scoped_allocator_adaptor;
169
170 __type _M_inner;
171 };
172
173 /// @endcond
174
175 /// An adaptor to recursively pass an allocator to the objects it constructs
176 template<typename _OuterAlloc, typename... _InnerAllocs>
177 class scoped_allocator_adaptor
178 : public _OuterAlloc
179 {
180 typedef allocator_traits<_OuterAlloc> __traits;
181
182 typedef __inner_type_impl<_OuterAlloc, _InnerAllocs...> __inner_type;
183 __inner_type _M_inner;
184
185 template<typename _Outer, typename... _Inner>
186 friend class scoped_allocator_adaptor;
187
188 template<typename...>
189 friend struct __inner_type_impl;
190
191 tuple<const _OuterAlloc&, const _InnerAllocs&...>
192 _M_tie() const noexcept
193 { return std::tuple_cat(std::tie(outer_allocator()), _M_inner._M_tie()); }
194
195 template<typename _Alloc>
196 using __outermost_alloc_traits
197 = allocator_traits<typename __outermost_type<_Alloc>::type>;
198
199#if ! __glibcxx_make_obj_using_allocator
200 template<typename _Tp, typename... _Args>
201 void
202 _M_construct(__uses_alloc0, _Tp* __p, _Args&&... __args)
203 {
204 typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
205 _O_traits::construct(__outermost(*this), __p,
206 std::forward<_Args>(__args)...);
207 }
208
209 typedef __uses_alloc1<typename __inner_type::__type> __uses_alloc1_;
210 typedef __uses_alloc2<typename __inner_type::__type> __uses_alloc2_;
211
212 template<typename _Tp, typename... _Args>
213 void
214 _M_construct(__uses_alloc1_, _Tp* __p, _Args&&... __args)
215 {
216 typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
217 _O_traits::construct(__outermost(*this), __p,
218 allocator_arg, inner_allocator(),
219 std::forward<_Args>(__args)...);
220 }
221
222 template<typename _Tp, typename... _Args>
223 void
224 _M_construct(__uses_alloc2_, _Tp* __p, _Args&&... __args)
225 {
226 typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
227 _O_traits::construct(__outermost(*this), __p,
228 std::forward<_Args>(__args)...,
229 inner_allocator());
230 }
231#endif // ! make_obj_using_allocator
232
233 template<typename _Alloc>
234 static _Alloc
235 _S_select_on_copy(const _Alloc& __a)
236 {
237 typedef allocator_traits<_Alloc> __a_traits;
238 return __a_traits::select_on_container_copy_construction(__a);
239 }
240
241 template<std::size_t... _Indices>
242 scoped_allocator_adaptor(tuple<const _OuterAlloc&,
243 const _InnerAllocs&...> __refs,
244 _Index_tuple<_Indices...>)
245 : _OuterAlloc(_S_select_on_copy(std::get<0>(__refs))),
246 _M_inner(_S_select_on_copy(std::get<_Indices+1>(__refs))...)
247 { }
248
249 // Used to constrain constructors to disallow invalid conversions.
250 template<typename _Alloc>
251 using _Constructible = typename enable_if<
252 is_constructible<_OuterAlloc, _Alloc>::value
253 >::type;
254
255 // _GLIBCXX_RESOLVE_LIB_DEFECTS
256 // 2975. Missing case for pair construction in scoped [...] allocators
257 template<typename _Tp>
258 struct __not_pair { using type = void; };
259
260 template<typename _Tp, typename _Up>
261 struct __not_pair<pair<_Tp, _Up>> { };
262
263 public:
264 typedef _OuterAlloc outer_allocator_type;
265 typedef typename __inner_type::__type inner_allocator_type;
266
267 typedef typename __traits::value_type value_type;
268 typedef typename __traits::size_type size_type;
269 typedef typename __traits::difference_type difference_type;
270 typedef typename __traits::pointer pointer;
271 typedef typename __traits::const_pointer const_pointer;
272 typedef typename __traits::void_pointer void_pointer;
273 typedef typename __traits::const_void_pointer const_void_pointer;
274
275 typedef typename __or_<
276 typename __traits::propagate_on_container_copy_assignment,
277 typename allocator_traits<_InnerAllocs>::
278 propagate_on_container_copy_assignment...>::type
279 propagate_on_container_copy_assignment;
280
281 typedef typename __or_<
282 typename __traits::propagate_on_container_move_assignment,
283 typename allocator_traits<_InnerAllocs>::
284 propagate_on_container_move_assignment...>::type
285 propagate_on_container_move_assignment;
286
287 typedef typename __or_<
288 typename __traits::propagate_on_container_swap,
289 typename allocator_traits<_InnerAllocs>::
290 propagate_on_container_swap...>::type
291 propagate_on_container_swap;
292
293 typedef typename __and_<
294 typename __traits::is_always_equal,
295 typename allocator_traits<_InnerAllocs>::is_always_equal...>::type
296 is_always_equal;
297
298 template <class _Tp>
299 struct rebind
300 {
301 typedef scoped_allocator_adaptor<
302 typename __traits::template rebind_alloc<_Tp>,
303 _InnerAllocs...> other;
304 };
305
306 scoped_allocator_adaptor() : _OuterAlloc(), _M_inner() { }
307
308 template<typename _Outer2, typename = _Constructible<_Outer2>>
309 scoped_allocator_adaptor(_Outer2&& __outer,
310 const _InnerAllocs&... __inner) noexcept
311 : _OuterAlloc(std::forward<_Outer2>(__outer)),
312 _M_inner(__inner...)
313 { }
314
315 scoped_allocator_adaptor(const scoped_allocator_adaptor& __other) noexcept
316 : _OuterAlloc(__other.outer_allocator()),
317 _M_inner(__other._M_inner)
318 { }
319
320 scoped_allocator_adaptor(scoped_allocator_adaptor&& __other) noexcept
321 : _OuterAlloc(std::move(__other.outer_allocator())),
322 _M_inner(std::move(__other._M_inner))
323 { }
324
325 template<typename _Outer2, typename = _Constructible<const _Outer2&>>
326 scoped_allocator_adaptor(
327 const scoped_allocator_adaptor<_Outer2, _InnerAllocs...>& __other
328 ) noexcept
329 : _OuterAlloc(__other.outer_allocator()),
330 _M_inner(__other._M_inner)
331 { }
332
333 template<typename _Outer2, typename = _Constructible<_Outer2>>
334 scoped_allocator_adaptor(
335 scoped_allocator_adaptor<_Outer2, _InnerAllocs...>&& __other) noexcept
336 : _OuterAlloc(std::move(__other.outer_allocator())),
337 _M_inner(std::move(__other._M_inner))
338 { }
339
340 scoped_allocator_adaptor&
341 operator=(const scoped_allocator_adaptor&) = default;
342
343 scoped_allocator_adaptor&
344 operator=(scoped_allocator_adaptor&&) = default;
345
346 inner_allocator_type&
347 inner_allocator() noexcept
348 { return _M_inner._M_get(this); }
349
350 const inner_allocator_type&
351 inner_allocator() const noexcept
352 { return _M_inner._M_get(this); }
353
354 outer_allocator_type&
355 outer_allocator() noexcept
356 { return static_cast<_OuterAlloc&>(*this); }
357
358 const outer_allocator_type&
359 outer_allocator() const noexcept
360 { return static_cast<const _OuterAlloc&>(*this); }
361
362 _GLIBCXX_NODISCARD pointer
363 allocate(size_type __n)
364 { return __traits::allocate(outer_allocator(), __n); }
365
366 _GLIBCXX_NODISCARD pointer
367 allocate(size_type __n, const_void_pointer __hint)
368 { return __traits::allocate(outer_allocator(), __n, __hint); }
369
370 void deallocate(pointer __p, size_type __n) noexcept
371 { return __traits::deallocate(outer_allocator(), __p, __n); }
372
373 size_type max_size() const
374 { return __traits::max_size(outer_allocator()); }
375
376#if ! __glibcxx_make_obj_using_allocator
377 template<typename _Tp, typename... _Args>
378 typename __not_pair<_Tp>::type
379 construct(_Tp* __p, _Args&&... __args)
380 {
381 auto& __inner = inner_allocator();
382 auto __use_tag
383 = std::__use_alloc<_Tp, inner_allocator_type, _Args...>(__inner);
384 _M_construct(__use_tag, __p, std::forward<_Args>(__args)...);
385 }
386
387 template<typename _T1, typename _T2, typename... _Args1,
388 typename... _Args2>
389 void
390 construct(pair<_T1, _T2>* __p, piecewise_construct_t,
391 tuple<_Args1...> __x, tuple<_Args2...> __y)
392 {
393 // _GLIBCXX_RESOLVE_LIB_DEFECTS
394 // 2203. wrong argument types for piecewise construction
395 auto& __inner = inner_allocator();
396 auto __x_use_tag
397 = std::__use_alloc<_T1, inner_allocator_type, _Args1...>(__inner);
398 auto __y_use_tag
399 = std::__use_alloc<_T2, inner_allocator_type, _Args2...>(__inner);
400 typename _Build_index_tuple<sizeof...(_Args1)>::__type __x_indices;
401 typename _Build_index_tuple<sizeof...(_Args2)>::__type __y_indices;
402 typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
403 _O_traits::construct(__outermost(*this), __p, piecewise_construct,
404 _M_construct_p(__x_use_tag, __x_indices, __x),
405 _M_construct_p(__y_use_tag, __y_indices, __y));
406 }
407
408 template<typename _T1, typename _T2>
409 void
410 construct(pair<_T1, _T2>* __p)
411 { construct(__p, piecewise_construct, tuple<>(), tuple<>()); }
412
413 template<typename _T1, typename _T2, typename _Up, typename _Vp>
414 void
415 construct(pair<_T1, _T2>* __p, _Up&& __u, _Vp&& __v)
416 {
417 construct(__p, piecewise_construct,
418 std::forward_as_tuple(std::forward<_Up>(__u)),
419 std::forward_as_tuple(std::forward<_Vp>(__v)));
420 }
421
422 template<typename _T1, typename _T2, typename _Up, typename _Vp>
423 void
424 construct(pair<_T1, _T2>* __p, const pair<_Up, _Vp>& __x)
425 {
426 construct(__p, piecewise_construct,
427 std::forward_as_tuple(__x.first),
428 std::forward_as_tuple(__x.second));
429 }
430
431 template<typename _T1, typename _T2, typename _Up, typename _Vp>
432 void
433 construct(pair<_T1, _T2>* __p, pair<_Up, _Vp>&& __x)
434 {
435 construct(__p, piecewise_construct,
436 std::forward_as_tuple(std::forward<_Up>(__x.first)),
437 std::forward_as_tuple(std::forward<_Vp>(__x.second)));
438 }
439#else // make_obj_using_allocator
440 template<typename _Tp, typename... _Args>
441 __attribute__((__nonnull__))
442 void
443 construct(_Tp* __p, _Args&&... __args)
444 {
445 typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
446 std::apply([__p, this](auto&&... __newargs) {
447 _O_traits::construct(__outermost(*this), __p,
448 std::forward<decltype(__newargs)>(__newargs)...);
449 },
450 uses_allocator_construction_args<_Tp>(inner_allocator(),
451 std::forward<_Args>(__args)...));
452 }
453#endif
454
455 template<typename _Tp>
456 void destroy(_Tp* __p)
457 {
458 typedef __outermost_alloc_traits<scoped_allocator_adaptor> _O_traits;
459 _O_traits::destroy(__outermost(*this), __p);
460 }
461
462 scoped_allocator_adaptor
463 select_on_container_copy_construction() const
464 {
465 typedef typename _Build_index_tuple<sizeof...(_InnerAllocs)>::__type
466 _Indices;
467 return scoped_allocator_adaptor(_M_tie(), _Indices());
468 }
469
470 template <typename _OutA1, typename _OutA2, typename... _InA>
471 friend bool
472 operator==(const scoped_allocator_adaptor<_OutA1, _InA...>& __a,
473 const scoped_allocator_adaptor<_OutA2, _InA...>& __b) noexcept;
474
475 private:
476#if ! __glibcxx_make_obj_using_allocator
477 template<typename _Ind, typename... _Args>
478 tuple<_Args&&...>
479 _M_construct_p(__uses_alloc0, _Ind, tuple<_Args...>& __t)
480 { return std::move(__t); }
481
482 template<size_t... _Ind, typename... _Args>
483 tuple<allocator_arg_t, inner_allocator_type&, _Args&&...>
484 _M_construct_p(__uses_alloc1_, _Index_tuple<_Ind...>,
485 tuple<_Args...>& __t)
486 {
487 return { allocator_arg, inner_allocator(),
488 std::get<_Ind>(std::move(__t))...
489 };
490 }
491
492 template<size_t... _Ind, typename... _Args>
493 tuple<_Args&&..., inner_allocator_type&>
494 _M_construct_p(__uses_alloc2_, _Index_tuple<_Ind...>,
495 tuple<_Args...>& __t)
496 {
497 return { std::get<_Ind>(std::move(__t))..., inner_allocator() };
498 }
499#endif // ! make_obj_using_allocator
500 };
501
502 /// @related std::scoped_allocator_adaptor
503 template <typename _OutA1, typename _OutA2, typename... _InA>
504 inline bool
505 operator==(const scoped_allocator_adaptor<_OutA1, _InA...>& __a,
506 const scoped_allocator_adaptor<_OutA2, _InA...>& __b) noexcept
507 {
508 return __a.outer_allocator() == __b.outer_allocator()
509 && __a._M_inner == __b._M_inner;
510 }
511
512#if __cpp_impl_three_way_comparison < 201907L
513 /// @related std::scoped_allocator_adaptor
514 template <typename _OutA1, typename _OutA2, typename... _InA>
515 inline bool
516 operator!=(const scoped_allocator_adaptor<_OutA1, _InA...>& __a,
517 const scoped_allocator_adaptor<_OutA2, _InA...>& __b) noexcept
518 { return !(__a == __b); }
519#endif
520
521 /// @}
522
523_GLIBCXX_END_NAMESPACE_VERSION
524} // namespace
525
526#endif // C++11
527
528#endif // _SCOPED_ALLOCATOR
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:2801
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:2676
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition move.h:127
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:2815
std::forward
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition move.h:70
std
ISO C++ entities toplevel namespace is std.
__gnu_debug::__base
constexpr _Iterator __base(_Iterator __it)
Definition helper_functions.h:315
std::scoped_allocator_adaptor
An adaptor to recursively pass an allocator to the objects it constructs.
Definition scoped_allocator:179
std::tuple
Primary class template, tuple.
Definition tuple:832
std::enable_if
Define a member typedef type only if a boolean constant is true.
Definition type_traits:131
std::is_constructible
is_constructible
Definition type_traits:1147
std::allocator_traits
Uniform interface to all allocator types.
Definition bits/alloc_traits.h:250
std::allocator_traits::propagate_on_container_move_assignment
__detected_or_t< false_type, __pocma, _Alloc > propagate_on_container_move_assignment
How the allocator is propagated on move assignment.
Definition bits/alloc_traits.h:351
std::allocator_traits::void_pointer
typename _Ptr< __v_pointer, void >::type void_pointer
The allocator's void pointer type.
Definition bits/alloc_traits.h:309
std::allocator_traits::pointer
__detected_or_t< value_type *, __pointer, _Alloc > pointer
The allocator's pointer type.
Definition bits/alloc_traits.h:261
std::allocator_traits::allocate
static constexpr pointer allocate(_Alloc &__a, size_type __n)
Allocate memory.
Definition bits/alloc_traits.h:384
std::allocator_traits::size_type
typename _Size< _Alloc, difference_type >::type size_type
The allocator's size type.
Definition bits/alloc_traits.h:333
std::allocator_traits::const_void_pointer
typename _Ptr< __cv_pointer, const void >::type const_void_pointer
The allocator's const void pointer type.
Definition bits/alloc_traits.h:317
std::allocator_traits::difference_type
typename _Diff< _Alloc, pointer >::type difference_type
The allocator's difference type.
Definition bits/alloc_traits.h:325
std::allocator_traits::const_pointer
typename _Ptr< __c_pointer, const value_type >::type const_pointer
The allocator's const pointer type.
Definition bits/alloc_traits.h:301
std::allocator_traits::value_type
_Alloc::value_type value_type
The allocated type.
Definition bits/alloc_traits.h:254
std::allocator_traits::deallocate
static constexpr void deallocate(_Alloc &__a, pointer __p, size_type __n)
Deallocate memory.
Definition bits/alloc_traits.h:416
std::allocator_traits::is_always_equal
typename __detected_or_t< is_empty< _Alloc >, __equal, _Alloc >::type is_always_equal
Whether all instances of the allocator type compare equal.
Definition bits/alloc_traits.h:369
std::allocator_traits::max_size
static constexpr size_type max_size(const _Alloc &__a) noexcept
The maximum supported allocation size.
Definition bits/alloc_traits.h:474
std::allocator_traits::propagate_on_container_copy_assignment
__detected_or_t< false_type, __pocca, _Alloc > propagate_on_container_copy_assignment
How the allocator is propagated on copy assignment.
Definition bits/alloc_traits.h:342
std::allocator_traits::propagate_on_container_swap
__detected_or_t< false_type, __pocs, _Alloc > propagate_on_container_swap
How the allocator is propagated on swap.
Definition bits/alloc_traits.h:360
std::pair
Struct holding two objects of arbitrary type.
Definition stl_pair.h:286
std::pair::first
_T1 first
The first member.
Definition stl_pair.h:290
std::pair::second
_T2 second
The second member.
Definition stl_pair.h:291
std::piecewise_construct_t
Tag type for piecewise construction of std::pair objects.
Definition stl_pair.h:79