1// Allocator traits -*- C++ -*-
2
3// Copyright (C) 2011-2017 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 bits/alloc_traits.h
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly. @headername{memory}
28 */
29
30#ifndef _ALLOC_TRAITS_H
31#define _ALLOC_TRAITS_H 1
32
33#if __cplusplus >= 201103L
34
35#include <bits/memoryfwd.h>
36#include <bits/ptr_traits.h>
37#include <ext/numeric_traits.h>
38
39#define __cpp_lib_allocator_traits_is_always_equal 201411
40
41namespace std _GLIBCXX_VISIBILITY(default)
42{
43_GLIBCXX_BEGIN_NAMESPACE_VERSION
44
45 struct __allocator_traits_base
46 {
47 template<typename _Tp, typename _Up, typename = void>
48 struct __rebind : __replace_first_arg<_Tp, _Up> { };
49
50 template<typename _Tp, typename _Up>
51 struct __rebind<_Tp, _Up,
52 __void_t<typename _Tp::template rebind<_Up>::other>>
53 { using type = typename _Tp::template rebind<_Up>::other; };
54
55 protected:
56 template<typename _Tp>
57 using __pointer = typename _Tp::pointer;
58 template<typename _Tp>
59 using __c_pointer = typename _Tp::const_pointer;
60 template<typename _Tp>
61 using __v_pointer = typename _Tp::void_pointer;
62 template<typename _Tp>
63 using __cv_pointer = typename _Tp::const_void_pointer;
64 template<typename _Tp>
65 using __pocca = typename _Tp::propagate_on_container_copy_assignment;
66 template<typename _Tp>
67 using __pocma = typename _Tp::propagate_on_container_move_assignment;
68 template<typename _Tp>
69 using __pocs = typename _Tp::propagate_on_container_swap;
70 template<typename _Tp>
71 using __equal = typename _Tp::is_always_equal;
72 };
73
74 template<typename _Alloc, typename _Up>
75 using __alloc_rebind
76 = typename __allocator_traits_base::template __rebind<_Alloc, _Up>::type;
77
78 /**
79 * @brief Uniform interface to all allocator types.
80 * @ingroup allocators
81 */
82 template<typename _Alloc>
83 struct allocator_traits : __allocator_traits_base
84 {
85 /// The allocator type
86 typedef _Alloc allocator_type;
87 /// The allocated type
88 typedef typename _Alloc::value_type value_type;
89
90 /**
91 * @brief The allocator's pointer type.
92 *
93 * @c Alloc::pointer if that type exists, otherwise @c value_type*
94 */
95 using pointer = __detected_or_t<value_type*, __pointer, _Alloc>;
96
97 private:
98 // Select _Func<_Alloc> or pointer_traits<pointer>::rebind<_Tp>
99 template<template<typename> class _Func, typename _Tp, typename = void>
100 struct _Ptr
101 {
102 using type = typename pointer_traits<pointer>::template rebind<_Tp>;
103 };
104
105 template<template<typename> class _Func, typename _Tp>
106 struct _Ptr<_Func, _Tp, __void_t<_Func<_Alloc>>>
107 {
108 using type = _Func<_Alloc>;
109 };
110
111 // Select _A2::difference_type or pointer_traits<_Ptr>::difference_type
112 template<typename _A2, typename _PtrT, typename = void>
113 struct _Diff
114 { using type = typename pointer_traits<_PtrT>::difference_type; };
115
116 template<typename _A2, typename _PtrT>
117 struct _Diff<_A2, _PtrT, __void_t<typename _A2::difference_type>>
118 { using type = typename _A2::difference_type; };
119
120 // Select _A2::size_type or make_unsigned<_DiffT>::type
121 template<typename _A2, typename _DiffT, typename = void>
122 struct _Size : make_unsigned<_DiffT> { };
123
124 template<typename _A2, typename _DiffT>
125 struct _Size<_A2, _DiffT, __void_t<typename _A2::size_type>>
126 { using type = typename _A2::size_type; };
127
128 public:
129 /**
130 * @brief The allocator's const pointer type.
131 *
132 * @c Alloc::const_pointer if that type exists, otherwise
133 * <tt> pointer_traits<pointer>::rebind<const value_type> </tt>
134 */
135 using const_pointer = typename _Ptr<__c_pointer, const value_type>::type;
136
137 /**
138 * @brief The allocator's void pointer type.
139 *
140 * @c Alloc::void_pointer if that type exists, otherwise
141 * <tt> pointer_traits<pointer>::rebind<void> </tt>
142 */
143 using void_pointer = typename _Ptr<__v_pointer, void>::type;
144
145 /**
146 * @brief The allocator's const void pointer type.
147 *
148 * @c Alloc::const_void_pointer if that type exists, otherwise
149 * <tt> pointer_traits<pointer>::rebind<const void> </tt>
150 */
151 using const_void_pointer = typename _Ptr<__cv_pointer, const void>::type;
152
153 /**
154 * @brief The allocator's difference type
155 *
156 * @c Alloc::difference_type if that type exists, otherwise
157 * <tt> pointer_traits<pointer>::difference_type </tt>
158 */
159 using difference_type = typename _Diff<_Alloc, pointer>::type;
160
161 /**
162 * @brief The allocator's size type
163 *
164 * @c Alloc::size_type if that type exists, otherwise
165 * <tt> make_unsigned<difference_type>::type </tt>
166 */
167 using size_type = typename _Size<_Alloc, difference_type>::type;
168
169 /**
170 * @brief How the allocator is propagated on copy assignment
171 *
172 * @c Alloc::propagate_on_container_copy_assignment if that type exists,
173 * otherwise @c false_type
174 */
175 using propagate_on_container_copy_assignment
176 = __detected_or_t<false_type, __pocca, _Alloc>;
177
178 /**
179 * @brief How the allocator is propagated on move assignment
180 *
181 * @c Alloc::propagate_on_container_move_assignment if that type exists,
182 * otherwise @c false_type
183 */
184 using propagate_on_container_move_assignment
185 = __detected_or_t<false_type, __pocma, _Alloc>;
186
187 /**
188 * @brief How the allocator is propagated on swap
189 *
190 * @c Alloc::propagate_on_container_swap if that type exists,
191 * otherwise @c false_type
192 */
193 using propagate_on_container_swap
194 = __detected_or_t<false_type, __pocs, _Alloc>;
195
196 /**
197 * @brief Whether all instances of the allocator type compare equal.
198 *
199 * @c Alloc::is_always_equal if that type exists,
200 * otherwise @c is_empty<Alloc>::type
201 */
202 using is_always_equal
203 = __detected_or_t<typename is_empty<_Alloc>::type, __equal, _Alloc>;
204
205 template<typename _Tp>
206 using rebind_alloc = __alloc_rebind<_Alloc, _Tp>;
207 template<typename _Tp>
208 using rebind_traits = allocator_traits<rebind_alloc<_Tp>>;
209
210 private:
211 template<typename _Alloc2>
212 static auto
213 _S_allocate(_Alloc2& __a, size_type __n, const_void_pointer __hint, int)
214 -> decltype(__a.allocate(__n, __hint))
215 { return __a.allocate(__n, __hint); }
216
217 template<typename _Alloc2>
218 static pointer
219 _S_allocate(_Alloc2& __a, size_type __n, const_void_pointer, ...)
220 { return __a.allocate(__n); }
221
222 template<typename _Tp, typename... _Args>
223 struct __construct_helper
224 {
225 template<typename _Alloc2,
226 typename = decltype(std::declval<_Alloc2*>()->construct(
227 std::declval<_Tp*>(), std::declval<_Args>()...))>
228 static true_type __test(int);
229
230 template<typename>
231 static false_type __test(...);
232
233 using type = decltype(__test<_Alloc>(0));
234 };
235
236 template<typename _Tp, typename... _Args>
237 using __has_construct
238 = typename __construct_helper<_Tp, _Args...>::type;
239
240 template<typename _Tp, typename... _Args>
241 static _Require<__has_construct<_Tp, _Args...>>
242 _S_construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
243 { __a.construct(__p, std::forward<_Args>(__args)...); }
244
245 template<typename _Tp, typename... _Args>
246 static
247 _Require<__and_<__not_<__has_construct<_Tp, _Args...>>,
248 is_constructible<_Tp, _Args...>>>
249 _S_construct(_Alloc&, _Tp* __p, _Args&&... __args)
250 { ::new((void*)__p) _Tp(std::forward<_Args>(__args)...); }
251
252 template<typename _Alloc2, typename _Tp>
253 static auto
254 _S_destroy(_Alloc2& __a, _Tp* __p, int)
255 -> decltype(__a.destroy(__p))
256 { __a.destroy(__p); }
257
258 template<typename _Alloc2, typename _Tp>
259 static void
260 _S_destroy(_Alloc2&, _Tp* __p, ...)
261 { __p->~_Tp(); }
262
263 template<typename _Alloc2>
264 static auto
265 _S_max_size(_Alloc2& __a, int)
266 -> decltype(__a.max_size())
267 { return __a.max_size(); }
268
269 template<typename _Alloc2>
270 static size_type
271 _S_max_size(_Alloc2&, ...)
272 {
273 // _GLIBCXX_RESOLVE_LIB_DEFECTS
274 // 2466. allocator_traits::max_size() default behavior is incorrect
275 return __gnu_cxx::__numeric_traits<size_type>::__max
276 / sizeof(value_type);
277 }
278
279 template<typename _Alloc2>
280 static auto
281 _S_select(_Alloc2& __a, int)
282 -> decltype(__a.select_on_container_copy_construction())
283 { return __a.select_on_container_copy_construction(); }
284
285 template<typename _Alloc2>
286 static _Alloc2
287 _S_select(_Alloc2& __a, ...)
288 { return __a; }
289
290 public:
291
292 /**
293 * @brief Allocate memory.
294 * @param __a An allocator.
295 * @param __n The number of objects to allocate space for.
296 *
297 * Calls @c a.allocate(n)
298 */
299 static pointer
300 allocate(_Alloc& __a, size_type __n)
301 { return __a.allocate(__n); }
302
303 /**
304 * @brief Allocate memory.
305 * @param __a An allocator.
306 * @param __n The number of objects to allocate space for.
307 * @param __hint Aid to locality.
308 * @return Memory of suitable size and alignment for @a n objects
309 * of type @c value_type
310 *
311 * Returns <tt> a.allocate(n, hint) </tt> if that expression is
312 * well-formed, otherwise returns @c a.allocate(n)
313 */
314 static pointer
315 allocate(_Alloc& __a, size_type __n, const_void_pointer __hint)
316 { return _S_allocate(__a, __n, __hint, 0); }
317
318 /**
319 * @brief Deallocate memory.
320 * @param __a An allocator.
321 * @param __p Pointer to the memory to deallocate.
322 * @param __n The number of objects space was allocated for.
323 *
324 * Calls <tt> a.deallocate(p, n) </tt>
325 */
326 static void
327 deallocate(_Alloc& __a, pointer __p, size_type __n)
328 { __a.deallocate(__p, __n); }
329
330 /**
331 * @brief Construct an object of type @a _Tp
332 * @param __a An allocator.
333 * @param __p Pointer to memory of suitable size and alignment for Tp
334 * @param __args Constructor arguments.
335 *
336 * Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt>
337 * if that expression is well-formed, otherwise uses placement-new
338 * to construct an object of type @a _Tp at location @a __p from the
339 * arguments @a __args...
340 */
341 template<typename _Tp, typename... _Args>
342 static auto construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
343 -> decltype(_S_construct(__a, __p, std::forward<_Args>(__args)...))
344 { _S_construct(__a, __p, std::forward<_Args>(__args)...); }
345
346 /**
347 * @brief Destroy an object of type @a _Tp
348 * @param __a An allocator.
349 * @param __p Pointer to the object to destroy
350 *
351 * Calls @c __a.destroy(__p) if that expression is well-formed,
352 * otherwise calls @c __p->~_Tp()
353 */
354 template<typename _Tp>
355 static void destroy(_Alloc& __a, _Tp* __p)
356 { _S_destroy(__a, __p, 0); }
357
358 /**
359 * @brief The maximum supported allocation size
360 * @param __a An allocator.
361 * @return @c __a.max_size() or @c numeric_limits<size_type>::max()
362 *
363 * Returns @c __a.max_size() if that expression is well-formed,
364 * otherwise returns @c numeric_limits<size_type>::max()
365 */
366 static size_type max_size(const _Alloc& __a) noexcept
367 { return _S_max_size(__a, 0); }
368
369 /**
370 * @brief Obtain an allocator to use when copying a container.
371 * @param __rhs An allocator.
372 * @return @c __rhs.select_on_container_copy_construction() or @a __rhs
373 *
374 * Returns @c __rhs.select_on_container_copy_construction() if that
375 * expression is well-formed, otherwise returns @a __rhs
376 */
377 static _Alloc
378 select_on_container_copy_construction(const _Alloc& __rhs)
379 { return _S_select(__rhs, 0); }
380 };
381
382 /// Partial specialization for std::allocator.
383 template<typename _Tp>
384 struct allocator_traits<allocator<_Tp>>
385 {
386 /// The allocator type
387 using allocator_type = allocator<_Tp>;
388 /// The allocated type
389 using value_type = _Tp;
390
391 /// The allocator's pointer type.
392 using pointer = _Tp*;
393
394 /// The allocator's const pointer type.
395 using const_pointer = const _Tp*;
396
397 /// The allocator's void pointer type.
398 using void_pointer = void*;
399
400 /// The allocator's const void pointer type.
401 using const_void_pointer = const void*;
402
403 /// The allocator's difference type
404 using difference_type = std::ptrdiff_t;
405
406 /// The allocator's size type
407 using size_type = std::size_t;
408
409 /// How the allocator is propagated on copy assignment
410 using propagate_on_container_copy_assignment = false_type;
411
412 /// How the allocator is propagated on move assignment
413 using propagate_on_container_move_assignment = true_type;
414
415 /// How the allocator is propagated on swap
416 using propagate_on_container_swap = false_type;
417
418 /// Whether all instances of the allocator type compare equal.
419 using is_always_equal = true_type;
420
421 template<typename _Up>
422 using rebind_alloc = allocator<_Up>;
423
424 template<typename _Up>
425 using rebind_traits = allocator_traits<allocator<_Up>>;
426
427 /**
428 * @brief Allocate memory.
429 * @param __a An allocator.
430 * @param __n The number of objects to allocate space for.
431 *
432 * Calls @c a.allocate(n)
433 */
434 static pointer
435 allocate(allocator_type& __a, size_type __n)
436 { return __a.allocate(__n); }
437
438 /**
439 * @brief Allocate memory.
440 * @param __a An allocator.
441 * @param __n The number of objects to allocate space for.
442 * @param __hint Aid to locality.
443 * @return Memory of suitable size and alignment for @a n objects
444 * of type @c value_type
445 *
446 * Returns <tt> a.allocate(n, hint) </tt>
447 */
448 static pointer
449 allocate(allocator_type& __a, size_type __n, const_void_pointer __hint)
450 { return __a.allocate(__n, __hint); }
451
452 /**
453 * @brief Deallocate memory.
454 * @param __a An allocator.
455 * @param __p Pointer to the memory to deallocate.
456 * @param __n The number of objects space was allocated for.
457 *
458 * Calls <tt> a.deallocate(p, n) </tt>
459 */
460 static void
461 deallocate(allocator_type& __a, pointer __p, size_type __n)
462 { __a.deallocate(__p, __n); }
463
464 /**
465 * @brief Construct an object of type @a _Up
466 * @param __a An allocator.
467 * @param __p Pointer to memory of suitable size and alignment for Tp
468 * @param __args Constructor arguments.
469 *
470 * Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt>
471 */
472 template<typename _Up, typename... _Args>
473 static void
474 construct(allocator_type& __a, _Up* __p, _Args&&... __args)
475 { __a.construct(__p, std::forward<_Args>(__args)...); }
476
477 /**
478 * @brief Destroy an object of type @a _Up
479 * @param __a An allocator.
480 * @param __p Pointer to the object to destroy
481 *
482 * Calls @c __a.destroy(__p).
483 */
484 template<typename _Up>
485 static void
486 destroy(allocator_type& __a, _Up* __p)
487 { __a.destroy(__p); }
488
489 /**
490 * @brief The maximum supported allocation size
491 * @param __a An allocator.
492 * @return @c __a.max_size()
493 */
494 static size_type
495 max_size(const allocator_type& __a) noexcept
496 { return __a.max_size(); }
497
498 /**
499 * @brief Obtain an allocator to use when copying a container.
500 * @param __rhs An allocator.
501 * @return @c __rhs
502 */
503 static allocator_type
504 select_on_container_copy_construction(const allocator_type& __rhs)
505 { return __rhs; }
506 };
507
508
509 template<typename _Alloc>
510 inline void
511 __do_alloc_on_copy(_Alloc& __one, const _Alloc& __two, true_type)
512 { __one = __two; }
513
514 template<typename _Alloc>
515 inline void
516 __do_alloc_on_copy(_Alloc&, const _Alloc&, false_type)
517 { }
518
519 template<typename _Alloc>
520 inline void __alloc_on_copy(_Alloc& __one, const _Alloc& __two)
521 {
522 typedef allocator_traits<_Alloc> __traits;
523 typedef typename __traits::propagate_on_container_copy_assignment __pocca;
524 __do_alloc_on_copy(__one, __two, __pocca());
525 }
526
527 template<typename _Alloc>
528 inline _Alloc __alloc_on_copy(const _Alloc& __a)
529 {
530 typedef allocator_traits<_Alloc> __traits;
531 return __traits::select_on_container_copy_construction(__a);
532 }
533
534 template<typename _Alloc>
535 inline void __do_alloc_on_move(_Alloc& __one, _Alloc& __two, true_type)
536 { __one = std::move(__two); }
537
538 template<typename _Alloc>
539 inline void __do_alloc_on_move(_Alloc&, _Alloc&, false_type)
540 { }
541
542 template<typename _Alloc>
543 inline void __alloc_on_move(_Alloc& __one, _Alloc& __two)
544 {
545 typedef allocator_traits<_Alloc> __traits;
546 typedef typename __traits::propagate_on_container_move_assignment __pocma;
547 __do_alloc_on_move(__one, __two, __pocma());
548 }
549
550 template<typename _Alloc>
551 inline void __do_alloc_on_swap(_Alloc& __one, _Alloc& __two, true_type)
552 {
553 using std::swap;
554 swap(__one, __two);
555 }
556
557 template<typename _Alloc>
558 inline void __do_alloc_on_swap(_Alloc&, _Alloc&, false_type)
559 { }
560
561 template<typename _Alloc>
562 inline void __alloc_on_swap(_Alloc& __one, _Alloc& __two)
563 {
564 typedef allocator_traits<_Alloc> __traits;
565 typedef typename __traits::propagate_on_container_swap __pocs;
566 __do_alloc_on_swap(__one, __two, __pocs());
567 }
568
569 template<typename _Alloc>
570 class __is_copy_insertable_impl
571 {
572 typedef allocator_traits<_Alloc> _Traits;
573
574 template<typename _Up, typename
575 = decltype(_Traits::construct(std::declval<_Alloc&>(),
576 std::declval<_Up*>(),
577 std::declval<const _Up&>()))>
578 static true_type
579 _M_select(int);
580
581 template<typename _Up>
582 static false_type
583 _M_select(...);
584
585 public:
586 typedef decltype(_M_select<typename _Alloc::value_type>(0)) type;
587 };
588
589 // true if _Alloc::value_type is CopyInsertable into containers using _Alloc
590 template<typename _Alloc>
591 struct __is_copy_insertable
592 : __is_copy_insertable_impl<_Alloc>::type
593 { };
594
595 // std::allocator<_Tp> just requires CopyConstructible
596 template<typename _Tp>
597 struct __is_copy_insertable<allocator<_Tp>>
598 : is_copy_constructible<_Tp>
599 { };
600
601#if __cplusplus >= 201103L
602 // Trait to detect Allocator-like types.
603 template<typename _Alloc, typename = void>
604 struct __is_allocator : false_type { };
605
606 template<typename _Alloc>
607 struct __is_allocator<_Alloc,
608 __void_t<typename _Alloc::value_type,
609 decltype(std::declval<_Alloc&>().allocate(size_t{}))>>
610 : true_type { };
611
612 template<typename _Alloc>
613 using _RequireAllocator
614 = typename enable_if<__is_allocator<_Alloc>::value, _Alloc>::type;
615#endif
616
617_GLIBCXX_END_NAMESPACE_VERSION
618} // namespace std
619
620#endif
621#endif
622