1 // Allocator traits -*- C++ -*-
2
3 // Copyright (C) 2011-2013 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 namespace std _GLIBCXX_VISIBILITY(default)
40 {
41 _GLIBCXX_BEGIN_NAMESPACE_VERSION
42
43 template<typename _Alloc, typename _Tp>
44 class __alloctr_rebind_helper
45 {
46 template<typename _Alloc2, typename _Tp2>
47 static constexpr bool
48 _S_chk(typename _Alloc2::template rebind<_Tp2>::other*)
49 { return true; }
50
51 template<typename, typename>
52 static constexpr bool
53 _S_chk(...)
54 { return false; }
55
56 public:
57 static const bool __value = _S_chk<_Alloc, _Tp>(nullptr);
58 };
59
60 template<typename _Alloc, typename _Tp>
61 const bool __alloctr_rebind_helper<_Alloc, _Tp>::__value;
62
63 template<typename _Alloc, typename _Tp,
64 bool = __alloctr_rebind_helper<_Alloc, _Tp>::__value>
65 struct __alloctr_rebind;
66
67 template<typename _Alloc, typename _Tp>
68 struct __alloctr_rebind<_Alloc, _Tp, true>
69 {
70 typedef typename _Alloc::template rebind<_Tp>::other __type;
71 };
72
73 template<template<typename, typename...> class _Alloc, typename _Tp,
74 typename _Up, typename... _Args>
75 struct __alloctr_rebind<_Alloc<_Up, _Args...>, _Tp, false>
76 {
77 typedef _Alloc<_Tp, _Args...> __type;
78 };
79
80 /**
81 * @brief Uniform interface to all allocator types.
82 * @ingroup allocators
83 */
84 template<typename _Alloc>
85 struct allocator_traits
86 {
87 /// The allocator type
88 typedef _Alloc allocator_type;
89 /// The allocated type
90 typedef typename _Alloc::value_type value_type;
91
92 #define _GLIBCXX_ALLOC_TR_NESTED_TYPE(_NTYPE, _ALT) \
93 private: \
94 template<typename _Tp> \
95 static typename _Tp::_NTYPE _S_##_NTYPE##_helper(_Tp*); \
96 static _ALT _S_##_NTYPE##_helper(...); \
97 typedef decltype(_S_##_NTYPE##_helper((_Alloc*)0)) __##_NTYPE; \
98 public:
99
100 _GLIBCXX_ALLOC_TR_NESTED_TYPE(pointer, value_type*)
101
102 /**
103 * @brief The allocator's pointer type.
104 *
105 * @c Alloc::pointer if that type exists, otherwise @c value_type*
106 */
107 typedef __pointer pointer;
108
109 _GLIBCXX_ALLOC_TR_NESTED_TYPE(const_pointer,
110 typename pointer_traits<pointer>::template rebind<const value_type>)
111
112 /**
113 * @brief The allocator's const pointer type.
114 *
115 * @c Alloc::const_pointer if that type exists, otherwise
116 * <tt> pointer_traits<pointer>::rebind<const value_type> </tt>
117 */
118 typedef __const_pointer const_pointer;
119
120 _GLIBCXX_ALLOC_TR_NESTED_TYPE(void_pointer,
121 typename pointer_traits<pointer>::template rebind<void>)
122
123 /**
124 * @brief The allocator's void pointer type.
125 *
126 * @c Alloc::void_pointer if that type exists, otherwise
127 * <tt> pointer_traits<pointer>::rebind<void> </tt>
128 */
129 typedef __void_pointer void_pointer;
130
131 _GLIBCXX_ALLOC_TR_NESTED_TYPE(const_void_pointer,
132 typename pointer_traits<pointer>::template rebind<const void>)
133
134 /**
135 * @brief The allocator's const void pointer type.
136 *
137 * @c Alloc::const_void_pointer if that type exists, otherwise
138 * <tt> pointer_traits<pointer>::rebind<const void> </tt>
139 */
140 typedef __const_void_pointer const_void_pointer;
141
142 _GLIBCXX_ALLOC_TR_NESTED_TYPE(difference_type,
143 typename pointer_traits<pointer>::difference_type)
144
145 /**
146 * @brief The allocator's difference type
147 *
148 * @c Alloc::difference_type if that type exists, otherwise
149 * <tt> pointer_traits<pointer>::difference_type </tt>
150 */
151 typedef __difference_type difference_type;
152
153 _GLIBCXX_ALLOC_TR_NESTED_TYPE(size_type,
154 typename make_unsigned<difference_type>::type)
155
156 /**
157 * @brief The allocator's size type
158 *
159 * @c Alloc::size_type if that type exists, otherwise
160 * <tt> make_unsigned<difference_type>::type </tt>
161 */
162 typedef __size_type size_type;
163
164 _GLIBCXX_ALLOC_TR_NESTED_TYPE(propagate_on_container_copy_assignment,
165 false_type)
166
167 /**
168 * @brief How the allocator is propagated on copy assignment
169 *
170 * @c Alloc::propagate_on_container_copy_assignment if that type exists,
171 * otherwise @c false_type
172 */
173 typedef __propagate_on_container_copy_assignment
174 propagate_on_container_copy_assignment;
175
176 _GLIBCXX_ALLOC_TR_NESTED_TYPE(propagate_on_container_move_assignment,
177 false_type)
178
179 /**
180 * @brief How the allocator is propagated on move assignment
181 *
182 * @c Alloc::propagate_on_container_move_assignment if that type exists,
183 * otherwise @c false_type
184 */
185 typedef __propagate_on_container_move_assignment
186 propagate_on_container_move_assignment;
187
188 _GLIBCXX_ALLOC_TR_NESTED_TYPE(propagate_on_container_swap,
189 false_type)
190
191 /**
192 * @brief How the allocator is propagated on swap
193 *
194 * @c Alloc::propagate_on_container_swap if that type exists,
195 * otherwise @c false_type
196 */
197 typedef __propagate_on_container_swap propagate_on_container_swap;
198
199 #undef _GLIBCXX_ALLOC_TR_NESTED_TYPE
200
201 template<typename _Tp>
202 using rebind_alloc = typename __alloctr_rebind<_Alloc, _Tp>::__type;
203 template<typename _Tp>
204 using rebind_traits = allocator_traits<rebind_alloc<_Tp>>;
205
206 private:
207 template<typename _Alloc2>
208 struct __allocate_helper
209 {
210 template<typename _Alloc3,
211 typename = decltype(std::declval<_Alloc3*>()->allocate(
212 std::declval<size_type>(),
213 std::declval<const_void_pointer>()))>
214 static true_type __test(int);
215
216 template<typename>
217 static false_type __test(...);
218
219 typedef decltype(__test<_Alloc>(0)) type;
220 static const bool value = type::value;
221 };
222
223 template<typename _Alloc2>
224 static typename
225 enable_if<__allocate_helper<_Alloc2>::value, pointer>::type
226 _S_allocate(_Alloc2& __a, size_type __n, const_void_pointer __hint)
227 { return __a.allocate(__n, __hint); }
228
229 template<typename _Alloc2>
230 static typename
231 enable_if<!__allocate_helper<_Alloc2>::value, pointer>::type
232 _S_allocate(_Alloc2& __a, size_type __n, ...)
233 { return __a.allocate(__n); }
234
235 template<typename _Tp, typename... _Args>
236 struct __construct_helper
237 {
238 template<typename _Alloc2,
239 typename = decltype(std::declval<_Alloc2*>()->construct(
240 std::declval<_Tp*>(), std::declval<_Args>()...))>
241 static true_type __test(int);
242
243 template<typename>
244 static false_type __test(...);
245
246 typedef decltype(__test<_Alloc>(0)) type;
247 static const bool value = type::value;
248 };
249
250 template<typename _Tp, typename... _Args>
251 static typename
252 enable_if<__construct_helper<_Tp, _Args...>::value, void>::type
253 _S_construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
254 { __a.construct(__p, std::forward<_Args>(__args)...); }
255
256 template<typename _Tp, typename... _Args>
257 static typename
258 enable_if<__and_<__not_<__construct_helper<_Tp, _Args...>>,
259 is_constructible<_Tp, _Args...>>::value, void>::type
260 _S_construct(_Alloc&, _Tp* __p, _Args&&... __args)
261 { ::new((void*)__p) _Tp(std::forward<_Args>(__args)...); }
262
263 template<typename _Tp>
264 struct __destroy_helper
265 {
266 template<typename _Alloc2,
267 typename = decltype(std::declval<_Alloc2*>()->destroy(
268 std::declval<_Tp*>()))>
269 static true_type __test(int);
270
271 template<typename>
272 static false_type __test(...);
273
274 typedef decltype(__test<_Alloc>(0)) type;
275 static const bool value = type::value;
276 };
277
278 template<typename _Tp>
279 static typename enable_if<__destroy_helper<_Tp>::value, void>::type
280 _S_destroy(_Alloc& __a, _Tp* __p)
281 { __a.destroy(__p); }
282
283 template<typename _Tp>
284 static typename enable_if<!__destroy_helper<_Tp>::value, void>::type
285 _S_destroy(_Alloc&, _Tp* __p)
286 { __p->~_Tp(); }
287
288 template<typename _Alloc2>
289 struct __maxsize_helper
290 {
291 template<typename _Alloc3,
292 typename = decltype(std::declval<_Alloc3*>()->max_size())>
293 static true_type __test(int);
294
295 template<typename>
296 static false_type __test(...);
297
298 typedef decltype(__test<_Alloc2>(0)) type;
299 static const bool value = type::value;
300 };
301
302 template<typename _Alloc2>
303 static typename
304 enable_if<__maxsize_helper<_Alloc2>::value, size_type>::type
305 _S_max_size(_Alloc2& __a)
306 { return __a.max_size(); }
307
308 template<typename _Alloc2>
309 static typename
310 enable_if<!__maxsize_helper<_Alloc2>::value, size_type>::type
311 _S_max_size(_Alloc2&)
312 { return __gnu_cxx::__numeric_traits<size_type>::__max; }
313
314 template<typename _Alloc2>
315 struct __select_helper
316 {
317 template<typename _Alloc3, typename
318 = decltype(std::declval<_Alloc3*>()
319 ->select_on_container_copy_construction())>
320 static true_type __test(int);
321
322 template<typename>
323 static false_type __test(...);
324
325 typedef decltype(__test<_Alloc2>(0)) type;
326 static const bool value = type::value;
327 };
328 template<typename _Alloc2>
329 static typename
330 enable_if<__select_helper<_Alloc2>::value, _Alloc2>::type
331 _S_select(_Alloc2& __a)
332 { return __a.select_on_container_copy_construction(); }
333
334 template<typename _Alloc2>
335 static typename
336 enable_if<!__select_helper<_Alloc2>::value, _Alloc2>::type
337 _S_select(_Alloc2& __a)
338 { return __a; }
339
340 public:
341
342 /**
343 * @brief Allocate memory.
344 * @param __a An allocator.
345 * @param __n The number of objects to allocate space for.
346 *
347 * Calls @c a.allocate(n)
348 */
349 static pointer
350 allocate(_Alloc& __a, size_type __n)
351 { return __a.allocate(__n); }
352
353 /**
354 * @brief Allocate memory.
355 * @param __a An allocator.
356 * @param __n The number of objects to allocate space for.
357 * @param __hint Aid to locality.
358 * @return Memory of suitable size and alignment for @a n objects
359 * of type @c value_type
360 *
361 * Returns <tt> a.allocate(n, hint) </tt> if that expression is
362 * well-formed, otherwise returns @c a.allocate(n)
363 */
364 static pointer
365 allocate(_Alloc& __a, size_type __n, const_void_pointer __hint)
366 { return _S_allocate(__a, __n, __hint); }
367
368 /**
369 * @brief Deallocate memory.
370 * @param __a An allocator.
371 * @param __p Pointer to the memory to deallocate.
372 * @param __n The number of objects space was allocated for.
373 *
374 * Calls <tt> a.deallocate(p, n) </tt>
375 */
376 static void deallocate(_Alloc& __a, pointer __p, size_type __n)
377 { __a.deallocate(__p, __n); }
378
379 /**
380 * @brief Construct an object of type @a _Tp
381 * @param __a An allocator.
382 * @param __p Pointer to memory of suitable size and alignment for Tp
383 * @param __args Constructor arguments.
384 *
385 * Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt>
386 * if that expression is well-formed, otherwise uses placement-new
387 * to construct an object of type @a _Tp at location @a __p from the
388 * arguments @a __args...
389 */
390 template<typename _Tp, typename... _Args>
391 static auto construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
392 -> decltype(_S_construct(__a, __p, std::forward<_Args>(__args)...))
393 { _S_construct(__a, __p, std::forward<_Args>(__args)...); }
394
395 /**
396 * @brief Destroy an object of type @a _Tp
397 * @param __a An allocator.
398 * @param __p Pointer to the object to destroy
399 *
400 * Calls @c __a.destroy(__p) if that expression is well-formed,
401 * otherwise calls @c __p->~_Tp()
402 */
403 template <class _Tp>
404 static void destroy(_Alloc& __a, _Tp* __p)
405 { _S_destroy(__a, __p); }
406
407 /**
408 * @brief The maximum supported allocation size
409 * @param __a An allocator.
410 * @return @c __a.max_size() or @c numeric_limits<size_type>::max()
411 *
412 * Returns @c __a.max_size() if that expression is well-formed,
413 * otherwise returns @c numeric_limits<size_type>::max()
414 */
415 static size_type max_size(const _Alloc& __a)
416 { return _S_max_size(__a); }
417
418 /**
419 * @brief Obtain an allocator to use when copying a container.
420 * @param __rhs An allocator.
421 * @return @c __rhs.select_on_container_copy_construction() or @a __rhs
422 *
423 * Returns @c __rhs.select_on_container_copy_construction() if that
424 * expression is well-formed, otherwise returns @a __rhs
425 */
426 static _Alloc
427 select_on_container_copy_construction(const _Alloc& __rhs)
428 { return _S_select(__rhs); }
429 };
430
431 template<typename _Alloc>
432 template<typename _Alloc2>
433 const bool allocator_traits<_Alloc>::__allocate_helper<_Alloc2>::value;
434
435 template<typename _Alloc>
436 template<typename _Tp, typename... _Args>
437 const bool
438 allocator_traits<_Alloc>::__construct_helper<_Tp, _Args...>::value;
439
440 template<typename _Alloc>
441 template<typename _Tp>
442 const bool allocator_traits<_Alloc>::__destroy_helper<_Tp>::value;
443
444 template<typename _Alloc>
445 template<typename _Alloc2>
446 const bool allocator_traits<_Alloc>::__maxsize_helper<_Alloc2>::value;
447
448 template<typename _Alloc>
449 template<typename _Alloc2>
450 const bool allocator_traits<_Alloc>::__select_helper<_Alloc2>::value;
451
452 template<typename _Alloc>
453 inline void
454 __do_alloc_on_copy(_Alloc& __one, const _Alloc& __two, true_type)
455 { __one = __two; }
456
457 template<typename _Alloc>
458 inline void
459 __do_alloc_on_copy(_Alloc&, const _Alloc&, false_type)
460 { }
461
462 template<typename _Alloc>
463 inline void __alloc_on_copy(_Alloc& __one, const _Alloc& __two)
464 {
465 typedef allocator_traits<_Alloc> __traits;
466 typedef typename __traits::propagate_on_container_copy_assignment __pocca;
467 __do_alloc_on_copy(__one, __two, __pocca());
468 }
469
470 template<typename _Alloc>
471 inline _Alloc __alloc_on_copy(const _Alloc& __a)
472 {
473 typedef allocator_traits<_Alloc> __traits;
474 return __traits::select_on_container_copy_construction(__a);
475 }
476
477 template<typename _Alloc>
478 inline void __do_alloc_on_move(_Alloc& __one, _Alloc& __two, true_type)
479 { __one = std::move(__two); }
480
481 template<typename _Alloc>
482 inline void __do_alloc_on_move(_Alloc&, _Alloc&, false_type)
483 { }
484
485 template<typename _Alloc>
486 inline void __alloc_on_move(_Alloc& __one, _Alloc& __two)
487 {
488 typedef allocator_traits<_Alloc> __traits;
489 typedef typename __traits::propagate_on_container_move_assignment __pocma;
490 __do_alloc_on_move(__one, __two, __pocma());
491 }
492
493 template<typename _Alloc>
494 inline void __do_alloc_on_swap(_Alloc& __one, _Alloc& __two, true_type)
495 {
496 using std::swap;
497 swap(__one, __two);
498 }
499
500 template<typename _Alloc>
501 inline void __do_alloc_on_swap(_Alloc&, _Alloc&, false_type)
502 { }
503
504 template<typename _Alloc>
505 inline void __alloc_on_swap(_Alloc& __one, _Alloc& __two)
506 {
507 typedef allocator_traits<_Alloc> __traits;
508 typedef typename __traits::propagate_on_container_swap __pocs;
509 __do_alloc_on_swap(__one, __two, __pocs());
510 }
511
512 template<typename _Alloc>
513 class __is_copy_insertable_impl
514 {
515 typedef allocator_traits<_Alloc> _Traits;
516
517 template<typename _Up, typename
518 = decltype(_Traits::construct(std::declval<_Alloc&>(),
519 std::declval<_Up*>(),
520 std::declval<const _Up&>()))>
521 static true_type
522 _M_select(int);
523
524 template<typename _Up>
525 static false_type
526 _M_select(...);
527
528 public:
529 typedef decltype(_M_select<typename _Alloc::value_type>(0)) type;
530 };
531
532 // true if _Alloc::value_type is CopyInsertable into containers using _Alloc
533 template<typename _Alloc>
534 struct __is_copy_insertable
535 : __is_copy_insertable_impl<_Alloc>::type
536 { };
537
538 // std::allocator<_Tp> just requires CopyConstructible
539 template<typename _Tp>
540 struct __is_copy_insertable<allocator<_Tp>>
541 : is_copy_constructible<_Tp>
542 { };
543
544 // Used to allow copy construction of unordered containers
545 template<bool> struct __allow_copy_cons { };
546
547 // Used to delete copy constructor of unordered containers
548 template<>
549 struct __allow_copy_cons<false>
550 {
551 __allow_copy_cons() = default;
552 __allow_copy_cons(const __allow_copy_cons&) = delete;
553 __allow_copy_cons(__allow_copy_cons&&) = default;
554 __allow_copy_cons& operator=(const __allow_copy_cons&) = default;
555 __allow_copy_cons& operator=(__allow_copy_cons&&) = default;
556 };
557
558 template<typename _Alloc>
559 using __check_copy_constructible
560 = __allow_copy_cons<__is_copy_insertable<_Alloc>::value>;
561
562 _GLIBCXX_END_NAMESPACE_VERSION
563 } // namespace std
564
565 #endif
566 #endif
567