1// Internal policy header for unordered_set and unordered_map -*- C++ -*-
2
3// Copyright (C) 2010-2024 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 bits/hashtable_policy.h
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly.
28 * @headername{unordered_map,unordered_set}
29 */
30
31#ifndef _HASHTABLE_POLICY_H
32#define _HASHTABLE_POLICY_H 1
33
34#include <tuple> // for std::tuple, std::forward_as_tuple
35#include <bits/functional_hash.h> // for __is_fast_hash
36#include <bits/stl_algobase.h> // for std::min, std::is_permutation.
37#include <bits/stl_pair.h> // for std::pair
38#include <ext/aligned_buffer.h> // for __gnu_cxx::__aligned_buffer
39#include <ext/alloc_traits.h> // for std::__alloc_rebind
40#include <ext/numeric_traits.h> // for __gnu_cxx::__int_traits
41
42namespace std _GLIBCXX_VISIBILITY(default)
43{
44_GLIBCXX_BEGIN_NAMESPACE_VERSION
45/// @cond undocumented
46
47 template<typename _Key, typename _Value, typename _Alloc,
48 typename _ExtractKey, typename _Equal,
49 typename _Hash, typename _RangeHash, typename _Unused,
50 typename _RehashPolicy, typename _Traits>
51 class _Hashtable;
52
53namespace __detail
54{
55 /**
56 * @defgroup hashtable-detail Base and Implementation Classes
57 * @ingroup unordered_associative_containers
58 * @{
59 */
60 template<typename _Key, typename _Value, typename _ExtractKey,
61 typename _Equal, typename _Hash, typename _RangeHash,
62 typename _Unused, typename _Traits>
63 struct _Hashtable_base;
64
65 // Helper function: return distance(first, last) for forward
66 // iterators, or 0/1 for input iterators.
67 template<typename _Iterator>
68 inline typename std::iterator_traits<_Iterator>::difference_type
69 __distance_fw(_Iterator __first, _Iterator __last,
70 std::input_iterator_tag)
71 { return __first != __last ? 1 : 0; }
72
73 template<typename _Iterator>
74 inline typename std::iterator_traits<_Iterator>::difference_type
75 __distance_fw(_Iterator __first, _Iterator __last,
76 std::forward_iterator_tag)
77 { return std::distance(__first, __last); }
78
79 template<typename _Iterator>
80 inline typename std::iterator_traits<_Iterator>::difference_type
81 __distance_fw(_Iterator __first, _Iterator __last)
82 { return __distance_fw(__first, __last,
83 std::__iterator_category(__first)); }
84
85 struct _Identity
86 {
87 template<typename _Tp>
88 _Tp&&
89 operator()(_Tp&& __x) const noexcept
90 { return std::forward<_Tp>(__x); }
91 };
92
93 struct _Select1st
94 {
95 template<typename _Pair>
96 struct __1st_type;
97
98 template<typename _Tp, typename _Up>
99 struct __1st_type<pair<_Tp, _Up>>
100 { using type = _Tp; };
101
102 template<typename _Tp, typename _Up>
103 struct __1st_type<const pair<_Tp, _Up>>
104 { using type = const _Tp; };
105
106 template<typename _Pair>
107 struct __1st_type<_Pair&>
108 { using type = typename __1st_type<_Pair>::type&; };
109
110 template<typename _Tp>
111 typename __1st_type<_Tp>::type&&
112 operator()(_Tp&& __x) const noexcept
113 { return std::forward<_Tp>(__x).first; }
114 };
115
116 template<typename _ExKey, typename _Value>
117 struct _ConvertToValueType;
118
119 template<typename _Value>
120 struct _ConvertToValueType<_Identity, _Value>
121 {
122 template<typename _Kt>
123 constexpr _Kt&&
124 operator()(_Kt&& __k) const noexcept
125 { return std::forward<_Kt>(__k); }
126 };
127
128 template<typename _Value>
129 struct _ConvertToValueType<_Select1st, _Value>
130 {
131 constexpr _Value&&
132 operator()(_Value&& __x) const noexcept
133 { return std::move(__x); }
134
135 constexpr const _Value&
136 operator()(const _Value& __x) const noexcept
137 { return __x; }
138
139 template<typename _Kt, typename _Val>
140 constexpr std::pair<_Kt, _Val>&&
141 operator()(std::pair<_Kt, _Val>&& __x) const noexcept
142 { return std::move(__x); }
143
144 template<typename _Kt, typename _Val>
145 constexpr const std::pair<_Kt, _Val>&
146 operator()(const std::pair<_Kt, _Val>& __x) const noexcept
147 { return __x; }
148 };
149
150 template<typename _ExKey>
151 struct _NodeBuilder;
152
153 template<>
154 struct _NodeBuilder<_Select1st>
155 {
156 template<typename _Kt, typename _Arg, typename _NodeGenerator>
157 static auto
158 _S_build(_Kt&& __k, _Arg&& __arg, const _NodeGenerator& __node_gen)
159 -> typename _NodeGenerator::__node_ptr
160 {
161 return __node_gen(std::forward<_Kt>(__k),
162 std::forward<_Arg>(__arg).second);
163 }
164 };
165
166 template<>
167 struct _NodeBuilder<_Identity>
168 {
169 template<typename _Kt, typename _Arg, typename _NodeGenerator>
170 static auto
171 _S_build(_Kt&& __k, _Arg&&, const _NodeGenerator& __node_gen)
172 -> typename _NodeGenerator::__node_ptr
173 { return __node_gen(std::forward<_Kt>(__k)); }
174 };
175
176 template<typename _HashtableAlloc, typename _NodePtr>
177 struct _NodePtrGuard
178 {
179 _HashtableAlloc& _M_h;
180 _NodePtr _M_ptr;
181
182 ~_NodePtrGuard()
183 {
184 if (_M_ptr)
185 _M_h._M_deallocate_node_ptr(_M_ptr);
186 }
187 };
188
189 template<typename _NodeAlloc>
190 struct _Hashtable_alloc;
191
192 // Functor recycling a pool of nodes and using allocation once the pool is
193 // empty.
194 template<typename _NodeAlloc>
195 struct _ReuseOrAllocNode
196 {
197 private:
198 using __node_alloc_type = _NodeAlloc;
199 using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
200 using __node_alloc_traits =
201 typename __hashtable_alloc::__node_alloc_traits;
202
203 public:
204 using __node_ptr = typename __hashtable_alloc::__node_ptr;
205
206 _ReuseOrAllocNode(__node_ptr __nodes, __hashtable_alloc& __h)
207 : _M_nodes(__nodes), _M_h(__h) { }
208 _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;
209
210 ~_ReuseOrAllocNode()
211 { _M_h._M_deallocate_nodes(_M_nodes); }
212
213 template<typename... _Args>
214 __node_ptr
215 operator()(_Args&&... __args) const
216 {
217 if (!_M_nodes)
218 return _M_h._M_allocate_node(std::forward<_Args>(__args)...);
219
220 __node_ptr __node = _M_nodes;
221 _M_nodes = _M_nodes->_M_next();
222 __node->_M_nxt = nullptr;
223 auto& __a = _M_h._M_node_allocator();
224 __node_alloc_traits::destroy(__a, __node->_M_valptr());
225 _NodePtrGuard<__hashtable_alloc, __node_ptr> __guard { _M_h, __node };
226 __node_alloc_traits::construct(__a, __node->_M_valptr(),
227 std::forward<_Args>(__args)...);
228 __guard._M_ptr = nullptr;
229 return __node;
230 }
231
232 private:
233 mutable __node_ptr _M_nodes;
234 __hashtable_alloc& _M_h;
235 };
236
237 // Functor similar to the previous one but without any pool of nodes to
238 // recycle.
239 template<typename _NodeAlloc>
240 struct _AllocNode
241 {
242 private:
243 using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
244
245 public:
246 using __node_ptr = typename __hashtable_alloc::__node_ptr;
247
248 _AllocNode(__hashtable_alloc& __h)
249 : _M_h(__h) { }
250
251 template<typename... _Args>
252 __node_ptr
253 operator()(_Args&&... __args) const
254 { return _M_h._M_allocate_node(std::forward<_Args>(__args)...); }
255
256 private:
257 __hashtable_alloc& _M_h;
258 };
259
260 // Auxiliary types used for all instantiations of _Hashtable nodes
261 // and iterators.
262
263 /**
264 * struct _Hashtable_traits
265 *
266 * Important traits for hash tables.
267 *
268 * @tparam _Cache_hash_code Boolean value. True if the value of
269 * the hash function is stored along with the value. This is a
270 * time-space tradeoff. Storing it may improve lookup speed by
271 * reducing the number of times we need to call the _Hash or _Equal
272 * functors.
273 *
274 * @tparam _Constant_iterators Boolean value. True if iterator and
275 * const_iterator are both constant iterator types. This is true
276 * for unordered_set and unordered_multiset, false for
277 * unordered_map and unordered_multimap.
278 *
279 * @tparam _Unique_keys Boolean value. True if the return value
280 * of _Hashtable::count(k) is always at most one, false if it may
281 * be an arbitrary number. This is true for unordered_set and
282 * unordered_map, false for unordered_multiset and
283 * unordered_multimap.
284 */
285 template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
286 struct _Hashtable_traits
287 {
288 using __hash_cached = __bool_constant<_Cache_hash_code>;
289 using __constant_iterators = __bool_constant<_Constant_iterators>;
290 using __unique_keys = __bool_constant<_Unique_keys>;
291 };
292
293 /**
294 * struct _Hashtable_hash_traits
295 *
296 * Important traits for hash tables depending on associated hasher.
297 *
298 */
299 template<typename _Hash>
300 struct _Hashtable_hash_traits
301 {
302 static constexpr std::size_t
303 __small_size_threshold() noexcept
304 { return std::__is_fast_hash<_Hash>::value ? 0 : 20; }
305 };
306
307 /**
308 * struct _Hash_node_base
309 *
310 * Nodes, used to wrap elements stored in the hash table. A policy
311 * template parameter of class template _Hashtable controls whether
312 * nodes also store a hash code. In some cases (e.g. strings) this
313 * may be a performance win.
314 */
315 struct _Hash_node_base
316 {
317 _Hash_node_base* _M_nxt;
318
319 _Hash_node_base() noexcept : _M_nxt() { }
320
321 _Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
322 };
323
324 /**
325 * struct _Hash_node_value_base
326 *
327 * Node type with the value to store.
328 */
329 template<typename _Value>
330 struct _Hash_node_value_base
331 {
332 typedef _Value value_type;
333
334 __gnu_cxx::__aligned_buffer<_Value> _M_storage;
335
336 [[__gnu__::__always_inline__]]
337 _Value*
338 _M_valptr() noexcept
339 { return _M_storage._M_ptr(); }
340
341 [[__gnu__::__always_inline__]]
342 const _Value*
343 _M_valptr() const noexcept
344 { return _M_storage._M_ptr(); }
345
346 [[__gnu__::__always_inline__]]
347 _Value&
348 _M_v() noexcept
349 { return *_M_valptr(); }
350
351 [[__gnu__::__always_inline__]]
352 const _Value&
353 _M_v() const noexcept
354 { return *_M_valptr(); }
355 };
356
357 /**
358 * Primary template struct _Hash_node_code_cache.
359 */
360 template<bool _Cache_hash_code>
361 struct _Hash_node_code_cache
362 { };
363
364 /**
365 * Specialization for node with cache, struct _Hash_node_code_cache.
366 */
367 template<>
368 struct _Hash_node_code_cache<true>
369 { std::size_t _M_hash_code; };
370
371 template<typename _Value, bool _Cache_hash_code>
372 struct _Hash_node_value
373 : _Hash_node_value_base<_Value>
374 , _Hash_node_code_cache<_Cache_hash_code>
375 { };
376
377 /**
378 * Primary template struct _Hash_node.
379 */
380 template<typename _Value, bool _Cache_hash_code>
381 struct _Hash_node
382 : _Hash_node_base
383 , _Hash_node_value<_Value, _Cache_hash_code>
384 {
385 _Hash_node*
386 _M_next() const noexcept
387 { return static_cast<_Hash_node*>(this->_M_nxt); }
388 };
389
390 /// Base class for node iterators.
391 template<typename _Value, bool _Cache_hash_code>
392 struct _Node_iterator_base
393 {
394 using __node_type = _Hash_node<_Value, _Cache_hash_code>;
395
396 __node_type* _M_cur;
397
398 _Node_iterator_base() : _M_cur(nullptr) { }
399 _Node_iterator_base(__node_type* __p) noexcept
400 : _M_cur(__p) { }
401
402 void
403 _M_incr() noexcept
404 { _M_cur = _M_cur->_M_next(); }
405
406 friend bool
407 operator==(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
408 noexcept
409 { return __x._M_cur == __y._M_cur; }
410
411#if __cpp_impl_three_way_comparison < 201907L
412 friend bool
413 operator!=(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
414 noexcept
415 { return __x._M_cur != __y._M_cur; }
416#endif
417 };
418
419 /// Node iterators, used to iterate through all the hashtable.
420 template<typename _Value, bool __constant_iterators, bool __cache>
421 struct _Node_iterator
422 : public _Node_iterator_base<_Value, __cache>
423 {
424 private:
425 using __base_type = _Node_iterator_base<_Value, __cache>;
426 using __node_type = typename __base_type::__node_type;
427
428 public:
429 using value_type = _Value;
430 using difference_type = std::ptrdiff_t;
431 using iterator_category = std::forward_iterator_tag;
432
433 using pointer = __conditional_t<__constant_iterators,
434 const value_type*, value_type*>;
435
436 using reference = __conditional_t<__constant_iterators,
437 const value_type&, value_type&>;
438
439 _Node_iterator() = default;
440
441 explicit
442 _Node_iterator(__node_type* __p) noexcept
443 : __base_type(__p) { }
444
445 reference
446 operator*() const noexcept
447 { return this->_M_cur->_M_v(); }
448
449 pointer
450 operator->() const noexcept
451 { return this->_M_cur->_M_valptr(); }
452
453 _Node_iterator&
454 operator++() noexcept
455 {
456 this->_M_incr();
457 return *this;
458 }
459
460 _Node_iterator
461 operator++(int) noexcept
462 {
463 _Node_iterator __tmp(*this);
464 this->_M_incr();
465 return __tmp;
466 }
467 };
468
469 /// Node const_iterators, used to iterate through all the hashtable.
470 template<typename _Value, bool __constant_iterators, bool __cache>
471 struct _Node_const_iterator
472 : public _Node_iterator_base<_Value, __cache>
473 {
474 private:
475 using __base_type = _Node_iterator_base<_Value, __cache>;
476 using __node_type = typename __base_type::__node_type;
477
478 public:
479 typedef _Value value_type;
480 typedef std::ptrdiff_t difference_type;
481 typedef std::forward_iterator_tag iterator_category;
482
483 typedef const value_type* pointer;
484 typedef const value_type& reference;
485
486 _Node_const_iterator() = default;
487
488 explicit
489 _Node_const_iterator(__node_type* __p) noexcept
490 : __base_type(__p) { }
491
492 _Node_const_iterator(const _Node_iterator<_Value, __constant_iterators,
493 __cache>& __x) noexcept
494 : __base_type(__x._M_cur) { }
495
496 reference
497 operator*() const noexcept
498 { return this->_M_cur->_M_v(); }
499
500 pointer
501 operator->() const noexcept
502 { return this->_M_cur->_M_valptr(); }
503
504 _Node_const_iterator&
505 operator++() noexcept
506 {
507 this->_M_incr();
508 return *this;
509 }
510
511 _Node_const_iterator
512 operator++(int) noexcept
513 {
514 _Node_const_iterator __tmp(*this);
515 this->_M_incr();
516 return __tmp;
517 }
518 };
519
520 // Many of class template _Hashtable's template parameters are policy
521 // classes. These are defaults for the policies.
522
523 /// Default range hashing function: use division to fold a large number
524 /// into the range [0, N).
525 struct _Mod_range_hashing
526 {
527 typedef std::size_t first_argument_type;
528 typedef std::size_t second_argument_type;
529 typedef std::size_t result_type;
530
531 result_type
532 operator()(first_argument_type __num,
533 second_argument_type __den) const noexcept
534 { return __num % __den; }
535 };
536
537 /// Default ranged hash function H. In principle it should be a
538 /// function object composed from objects of type H1 and H2 such that
539 /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
540 /// h1 and h2. So instead we'll just use a tag to tell class template
541 /// hashtable to do that composition.
542 struct _Default_ranged_hash { };
543
544 /// Default value for rehash policy. Bucket size is (usually) the
545 /// smallest prime that keeps the load factor small enough.
546 struct _Prime_rehash_policy
547 {
548 using __has_load_factor = true_type;
549
550 _Prime_rehash_policy(float __z = 1.0) noexcept
551 : _M_max_load_factor(__z), _M_next_resize(0) { }
552
553 float
554 max_load_factor() const noexcept
555 { return _M_max_load_factor; }
556
557 // Return a bucket size no smaller than n.
558 std::size_t
559 _M_next_bkt(std::size_t __n) const;
560
561 // Return a bucket count appropriate for n elements
562 std::size_t
563 _M_bkt_for_elements(std::size_t __n) const
564 { return __builtin_ceil(__n / (double)_M_max_load_factor); }
565
566 // __n_bkt is current bucket count, __n_elt is current element count,
567 // and __n_ins is number of elements to be inserted. Do we need to
568 // increase bucket count? If so, return make_pair(true, n), where n
569 // is the new bucket count. If not, return make_pair(false, 0).
570 std::pair<bool, std::size_t>
571 _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
572 std::size_t __n_ins) const;
573
574 typedef std::size_t _State;
575
576 _State
577 _M_state() const
578 { return _M_next_resize; }
579
580 void
581 _M_reset() noexcept
582 { _M_next_resize = 0; }
583
584 void
585 _M_reset(_State __state)
586 { _M_next_resize = __state; }
587
588 static const std::size_t _S_growth_factor = 2;
589
590 float _M_max_load_factor;
591 mutable std::size_t _M_next_resize;
592 };
593
594 /// Range hashing function assuming that second arg is a power of 2.
595 struct _Mask_range_hashing
596 {
597 typedef std::size_t first_argument_type;
598 typedef std::size_t second_argument_type;
599 typedef std::size_t result_type;
600
601 result_type
602 operator()(first_argument_type __num,
603 second_argument_type __den) const noexcept
604 { return __num & (__den - 1); }
605 };
606
607 /// Compute closest power of 2 not less than __n
608 inline std::size_t
609 __clp2(std::size_t __n) noexcept
610 {
611 using __gnu_cxx::__int_traits;
612 // Equivalent to return __n ? std::bit_ceil(__n) : 0;
613 if (__n < 2)
614 return __n;
615 const unsigned __lz = sizeof(size_t) > sizeof(long)
616 ? __builtin_clzll(__n - 1ull)
617 : __builtin_clzl(__n - 1ul);
618 // Doing two shifts avoids undefined behaviour when __lz == 0.
619 return (size_t(1) << (__int_traits<size_t>::__digits - __lz - 1)) << 1;
620 }
621
622 /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
623 /// operations.
624 struct _Power2_rehash_policy
625 {
626 using __has_load_factor = true_type;
627
628 _Power2_rehash_policy(float __z = 1.0) noexcept
629 : _M_max_load_factor(__z), _M_next_resize(0) { }
630
631 float
632 max_load_factor() const noexcept
633 { return _M_max_load_factor; }
634
635 // Return a bucket size no smaller than n (as long as n is not above the
636 // highest power of 2).
637 std::size_t
638 _M_next_bkt(std::size_t __n) noexcept
639 {
640 if (__n == 0)
641 // Special case on container 1st initialization with 0 bucket count
642 // hint. We keep _M_next_resize to 0 to make sure that next time we
643 // want to add an element allocation will take place.
644 return 1;
645
646 const auto __max_width = std::min<size_t>(a: sizeof(size_t), b: 8);
647 const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
648 std::size_t __res = __clp2(__n);
649
650 if (__res == 0)
651 __res = __max_bkt;
652 else if (__res == 1)
653 // If __res is 1 we force it to 2 to make sure there will be an
654 // allocation so that nothing need to be stored in the initial
655 // single bucket
656 __res = 2;
657
658 if (__res == __max_bkt)
659 // Set next resize to the max value so that we never try to rehash again
660 // as we already reach the biggest possible bucket number.
661 // Note that it might result in max_load_factor not being respected.
662 _M_next_resize = size_t(-1);
663 else
664 _M_next_resize
665 = __builtin_floor(__res * (double)_M_max_load_factor);
666
667 return __res;
668 }
669
670 // Return a bucket count appropriate for n elements
671 std::size_t
672 _M_bkt_for_elements(std::size_t __n) const noexcept
673 { return __builtin_ceil(__n / (double)_M_max_load_factor); }
674
675 // __n_bkt is current bucket count, __n_elt is current element count,
676 // and __n_ins is number of elements to be inserted. Do we need to
677 // increase bucket count? If so, return make_pair(true, n), where n
678 // is the new bucket count. If not, return make_pair(false, 0).
679 std::pair<bool, std::size_t>
680 _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
681 std::size_t __n_ins) noexcept
682 {
683 if (__n_elt + __n_ins > _M_next_resize)
684 {
685 // If _M_next_resize is 0 it means that we have nothing allocated so
686 // far and that we start inserting elements. In this case we start
687 // with an initial bucket size of 11.
688 double __min_bkts
689 = std::max<std::size_t>(a: __n_elt + __n_ins, b: _M_next_resize ? 0 : 11)
690 / (double)_M_max_load_factor;
691 if (__min_bkts >= __n_bkt)
692 return { true,
693 _M_next_bkt(n: std::max<std::size_t>(a: __builtin_floor(__min_bkts) + 1,
694 b: __n_bkt * _S_growth_factor)) };
695
696 _M_next_resize
697 = __builtin_floor(__n_bkt * (double)_M_max_load_factor);
698 return { false, 0 };
699 }
700 else
701 return { false, 0 };
702 }
703
704 typedef std::size_t _State;
705
706 _State
707 _M_state() const noexcept
708 { return _M_next_resize; }
709
710 void
711 _M_reset() noexcept
712 { _M_next_resize = 0; }
713
714 void
715 _M_reset(_State __state) noexcept
716 { _M_next_resize = __state; }
717
718 static const std::size_t _S_growth_factor = 2;
719
720 float _M_max_load_factor;
721 std::size_t _M_next_resize;
722 };
723
724 template<typename _RehashPolicy>
725 struct _RehashStateGuard
726 {
727 _RehashPolicy* _M_guarded_obj;
728 typename _RehashPolicy::_State _M_prev_state;
729
730 _RehashStateGuard(_RehashPolicy& __policy)
731 : _M_guarded_obj(std::__addressof(__policy))
732 , _M_prev_state(__policy._M_state())
733 { }
734 _RehashStateGuard(const _RehashStateGuard&) = delete;
735
736 ~_RehashStateGuard()
737 {
738 if (_M_guarded_obj)
739 _M_guarded_obj->_M_reset(_M_prev_state);
740 }
741 };
742
743 // Base classes for std::_Hashtable. We define these base classes
744 // because in some cases we want to do different things depending on
745 // the value of a policy class. In some cases the policy class
746 // affects which member functions and nested typedefs are defined;
747 // we handle that by specializing base class templates. Several of
748 // the base class templates need to access other members of class
749 // template _Hashtable, so we use a variant of the "Curiously
750 // Recurring Template Pattern" (CRTP) technique.
751
752 /**
753 * Primary class template _Map_base.
754 *
755 * If the hashtable has a value type of the form pair<const T1, T2> and
756 * a key extraction policy (_ExtractKey) that returns the first part
757 * of the pair, the hashtable gets a mapped_type typedef. If it
758 * satisfies those criteria and also has unique keys, then it also
759 * gets an operator[].
760 */
761 template<typename _Key, typename _Value, typename _Alloc,
762 typename _ExtractKey, typename _Equal,
763 typename _Hash, typename _RangeHash, typename _Unused,
764 typename _RehashPolicy, typename _Traits,
765 bool _Unique_keys = _Traits::__unique_keys::value>
766 struct _Map_base { };
767
768 /// Partial specialization, __unique_keys set to false, std::pair value type.
769 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
770 typename _Hash, typename _RangeHash, typename _Unused,
771 typename _RehashPolicy, typename _Traits>
772 struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
773 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
774 {
775 using mapped_type = _Val;
776 };
777
778 /// Partial specialization, __unique_keys set to true.
779 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
780 typename _Hash, typename _RangeHash, typename _Unused,
781 typename _RehashPolicy, typename _Traits>
782 struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
783 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
784 {
785 private:
786 using __hashtable_base = _Hashtable_base<_Key, pair<const _Key, _Val>,
787 _Select1st, _Equal, _Hash,
788 _RangeHash, _Unused,
789 _Traits>;
790
791 using __hashtable = _Hashtable<_Key, pair<const _Key, _Val>, _Alloc,
792 _Select1st, _Equal, _Hash, _RangeHash,
793 _Unused, _RehashPolicy, _Traits>;
794
795 using __hash_code = typename __hashtable_base::__hash_code;
796
797 public:
798 using key_type = typename __hashtable_base::key_type;
799 using mapped_type = _Val;
800
801 mapped_type&
802 operator[](const key_type& __k);
803
804 mapped_type&
805 operator[](key_type&& __k);
806
807 // _GLIBCXX_RESOLVE_LIB_DEFECTS
808 // DR 761. unordered_map needs an at() member function.
809 mapped_type&
810 at(const key_type& __k)
811 {
812 auto __ite = static_cast<__hashtable*>(this)->find(__k);
813 if (!__ite._M_cur)
814 __throw_out_of_range(__N("unordered_map::at"));
815 return __ite->second;
816 }
817
818 const mapped_type&
819 at(const key_type& __k) const
820 {
821 auto __ite = static_cast<const __hashtable*>(this)->find(__k);
822 if (!__ite._M_cur)
823 __throw_out_of_range(__N("unordered_map::at"));
824 return __ite->second;
825 }
826 };
827
828 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
829 typename _Hash, typename _RangeHash, typename _Unused,
830 typename _RehashPolicy, typename _Traits>
831 auto
832 _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
833 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
834 operator[](const key_type& __k)
835 -> mapped_type&
836 {
837 __hashtable* __h = static_cast<__hashtable*>(this);
838 __hash_code __code = __h->_M_hash_code(__k);
839 std::size_t __bkt = __h->_M_bucket_index(__code);
840 if (auto __node = __h->_M_find_node(__bkt, __k, __code))
841 return __node->_M_v().second;
842
843 typename __hashtable::_Scoped_node __node {
844 __h,
845 std::piecewise_construct,
846 std::tuple<const key_type&>(__k),
847 std::tuple<>()
848 };
849 auto __pos
850 = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
851 __node._M_node = nullptr;
852 return __pos->second;
853 }
854
855 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
856 typename _Hash, typename _RangeHash, typename _Unused,
857 typename _RehashPolicy, typename _Traits>
858 auto
859 _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
860 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
861 operator[](key_type&& __k)
862 -> mapped_type&
863 {
864 __hashtable* __h = static_cast<__hashtable*>(this);
865 __hash_code __code = __h->_M_hash_code(__k);
866 std::size_t __bkt = __h->_M_bucket_index(__code);
867 if (auto __node = __h->_M_find_node(__bkt, __k, __code))
868 return __node->_M_v().second;
869
870 typename __hashtable::_Scoped_node __node {
871 __h,
872 std::piecewise_construct,
873 std::forward_as_tuple(std::move(__k)),
874 std::tuple<>()
875 };
876 auto __pos
877 = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
878 __node._M_node = nullptr;
879 return __pos->second;
880 }
881
882 // Partial specialization for unordered_map<const T, U>, see PR 104174.
883 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
884 typename _Hash, typename _RangeHash, typename _Unused,
885 typename _RehashPolicy, typename _Traits, bool __uniq>
886 struct _Map_base<const _Key, pair<const _Key, _Val>,
887 _Alloc, _Select1st, _Equal, _Hash,
888 _RangeHash, _Unused, _RehashPolicy, _Traits, __uniq>
889 : _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal, _Hash,
890 _RangeHash, _Unused, _RehashPolicy, _Traits, __uniq>
891 { };
892
893 /**
894 * Primary class template _Insert_base.
895 *
896 * Defines @c insert member functions appropriate to all _Hashtables.
897 */
898 template<typename _Key, typename _Value, typename _Alloc,
899 typename _ExtractKey, typename _Equal,
900 typename _Hash, typename _RangeHash, typename _Unused,
901 typename _RehashPolicy, typename _Traits>
902 struct _Insert_base
903 {
904 protected:
905 using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
906 _Equal, _Hash, _RangeHash,
907 _Unused, _Traits>;
908
909 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
910 _Hash, _RangeHash,
911 _Unused, _RehashPolicy, _Traits>;
912
913 using __hash_cached = typename _Traits::__hash_cached;
914 using __constant_iterators = typename _Traits::__constant_iterators;
915
916 using __hashtable_alloc = _Hashtable_alloc<
917 __alloc_rebind<_Alloc, _Hash_node<_Value,
918 __hash_cached::value>>>;
919
920 using value_type = typename __hashtable_base::value_type;
921 using size_type = typename __hashtable_base::size_type;
922
923 using __unique_keys = typename _Traits::__unique_keys;
924 using __node_alloc_type = typename __hashtable_alloc::__node_alloc_type;
925 using __node_gen_type = _AllocNode<__node_alloc_type>;
926
927 __hashtable&
928 _M_conjure_hashtable()
929 { return *(static_cast<__hashtable*>(this)); }
930
931 template<typename _InputIterator, typename _NodeGetter>
932 void
933 _M_insert_range(_InputIterator __first, _InputIterator __last,
934 const _NodeGetter&, true_type __uks);
935
936 template<typename _InputIterator, typename _NodeGetter>
937 void
938 _M_insert_range(_InputIterator __first, _InputIterator __last,
939 const _NodeGetter&, false_type __uks);
940
941 public:
942 using iterator = _Node_iterator<_Value, __constant_iterators::value,
943 __hash_cached::value>;
944
945 using const_iterator = _Node_const_iterator<_Value,
946 __constant_iterators::value,
947 __hash_cached::value>;
948
949 using __ireturn_type = __conditional_t<__unique_keys::value,
950 std::pair<iterator, bool>,
951 iterator>;
952
953 __ireturn_type
954 insert(const value_type& __v)
955 {
956 __hashtable& __h = _M_conjure_hashtable();
957 __node_gen_type __node_gen(__h);
958 return __h._M_insert(__v, __node_gen, __unique_keys{});
959 }
960
961 iterator
962 insert(const_iterator __hint, const value_type& __v)
963 {
964 __hashtable& __h = _M_conjure_hashtable();
965 __node_gen_type __node_gen(__h);
966 return __h._M_insert(__hint, __v, __node_gen, __unique_keys{});
967 }
968
969 template<typename _KType, typename... _Args>
970 std::pair<iterator, bool>
971 try_emplace(const_iterator, _KType&& __k, _Args&&... __args)
972 {
973 __hashtable& __h = _M_conjure_hashtable();
974 auto __code = __h._M_hash_code(__k);
975 std::size_t __bkt = __h._M_bucket_index(__code);
976 if (auto __node = __h._M_find_node(__bkt, __k, __code))
977 return { iterator(__node), false };
978
979 typename __hashtable::_Scoped_node __node {
980 &__h,
981 std::piecewise_construct,
982 std::forward_as_tuple(std::forward<_KType>(__k)),
983 std::forward_as_tuple(std::forward<_Args>(__args)...)
984 };
985 auto __it
986 = __h._M_insert_unique_node(__bkt, __code, __node._M_node);
987 __node._M_node = nullptr;
988 return { __it, true };
989 }
990
991 void
992 insert(initializer_list<value_type> __l)
993 { this->insert(__l.begin(), __l.end()); }
994
995 template<typename _InputIterator>
996 void
997 insert(_InputIterator __first, _InputIterator __last)
998 {
999 __hashtable& __h = _M_conjure_hashtable();
1000 __node_gen_type __node_gen(__h);
1001 return _M_insert_range(__first, __last, __node_gen, __unique_keys{});
1002 }
1003 };
1004
1005 template<typename _Key, typename _Value, typename _Alloc,
1006 typename _ExtractKey, typename _Equal,
1007 typename _Hash, typename _RangeHash, typename _Unused,
1008 typename _RehashPolicy, typename _Traits>
1009 template<typename _InputIterator, typename _NodeGetter>
1010 void
1011 _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1012 _Hash, _RangeHash, _Unused,
1013 _RehashPolicy, _Traits>::
1014 _M_insert_range(_InputIterator __first, _InputIterator __last,
1015 const _NodeGetter& __node_gen, true_type __uks)
1016 {
1017 __hashtable& __h = _M_conjure_hashtable();
1018 for (; __first != __last; ++__first)
1019 __h._M_insert(*__first, __node_gen, __uks);
1020 }
1021
1022 template<typename _Key, typename _Value, typename _Alloc,
1023 typename _ExtractKey, typename _Equal,
1024 typename _Hash, typename _RangeHash, typename _Unused,
1025 typename _RehashPolicy, typename _Traits>
1026 template<typename _InputIterator, typename _NodeGetter>
1027 void
1028 _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1029 _Hash, _RangeHash, _Unused,
1030 _RehashPolicy, _Traits>::
1031 _M_insert_range(_InputIterator __first, _InputIterator __last,
1032 const _NodeGetter& __node_gen, false_type __uks)
1033 {
1034 using __rehash_guard_t = typename __hashtable::__rehash_guard_t;
1035 using __pair_type = std::pair<bool, std::size_t>;
1036
1037 size_type __n_elt = __detail::__distance_fw(__first, __last);
1038 if (__n_elt == 0)
1039 return;
1040
1041 __hashtable& __h = _M_conjure_hashtable();
1042 __rehash_guard_t __rehash_guard(__h._M_rehash_policy);
1043 __pair_type __do_rehash
1044 = __h._M_rehash_policy._M_need_rehash(__h._M_bucket_count,
1045 __h._M_element_count,
1046 __n_elt);
1047
1048 if (__do_rehash.first)
1049 __h._M_rehash(__do_rehash.second, __uks);
1050
1051 __rehash_guard._M_guarded_obj = nullptr;
1052 for (; __first != __last; ++__first)
1053 __h._M_insert(*__first, __node_gen, __uks);
1054 }
1055
1056 /**
1057 * Primary class template _Insert.
1058 *
1059 * Defines @c insert member functions that depend on _Hashtable policies,
1060 * via partial specializations.
1061 */
1062 template<typename _Key, typename _Value, typename _Alloc,
1063 typename _ExtractKey, typename _Equal,
1064 typename _Hash, typename _RangeHash, typename _Unused,
1065 typename _RehashPolicy, typename _Traits,
1066 bool _Constant_iterators = _Traits::__constant_iterators::value>
1067 struct _Insert;
1068
1069 /// Specialization.
1070 template<typename _Key, typename _Value, typename _Alloc,
1071 typename _ExtractKey, typename _Equal,
1072 typename _Hash, typename _RangeHash, typename _Unused,
1073 typename _RehashPolicy, typename _Traits>
1074 struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1075 _Hash, _RangeHash, _Unused,
1076 _RehashPolicy, _Traits, true>
1077 : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1078 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>
1079 {
1080 using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
1081 _Equal, _Hash, _RangeHash, _Unused,
1082 _RehashPolicy, _Traits>;
1083
1084 using value_type = typename __base_type::value_type;
1085 using iterator = typename __base_type::iterator;
1086 using const_iterator = typename __base_type::const_iterator;
1087 using __ireturn_type = typename __base_type::__ireturn_type;
1088
1089 using __unique_keys = typename __base_type::__unique_keys;
1090 using __hashtable = typename __base_type::__hashtable;
1091 using __node_gen_type = typename __base_type::__node_gen_type;
1092
1093 using __base_type::insert;
1094
1095 __ireturn_type
1096 insert(value_type&& __v)
1097 {
1098 __hashtable& __h = this->_M_conjure_hashtable();
1099 __node_gen_type __node_gen(__h);
1100 return __h._M_insert(std::move(__v), __node_gen, __unique_keys{});
1101 }
1102
1103 iterator
1104 insert(const_iterator __hint, value_type&& __v)
1105 {
1106 __hashtable& __h = this->_M_conjure_hashtable();
1107 __node_gen_type __node_gen(__h);
1108 return __h._M_insert(__hint, std::move(__v), __node_gen,
1109 __unique_keys{});
1110 }
1111 };
1112
1113 /// Specialization.
1114 template<typename _Key, typename _Value, typename _Alloc,
1115 typename _ExtractKey, typename _Equal,
1116 typename _Hash, typename _RangeHash, typename _Unused,
1117 typename _RehashPolicy, typename _Traits>
1118 struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1119 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
1120 : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1121 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>
1122 {
1123 using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
1124 _Equal, _Hash, _RangeHash, _Unused,
1125 _RehashPolicy, _Traits>;
1126 using value_type = typename __base_type::value_type;
1127 using iterator = typename __base_type::iterator;
1128 using const_iterator = typename __base_type::const_iterator;
1129
1130 using __unique_keys = typename __base_type::__unique_keys;
1131 using __hashtable = typename __base_type::__hashtable;
1132 using __ireturn_type = typename __base_type::__ireturn_type;
1133
1134 using __base_type::insert;
1135
1136 template<typename _Pair>
1137 using __is_cons = std::is_constructible<value_type, _Pair&&>;
1138
1139 template<typename _Pair>
1140 using _IFcons = std::enable_if<__is_cons<_Pair>::value>;
1141
1142 template<typename _Pair>
1143 using _IFconsp = typename _IFcons<_Pair>::type;
1144
1145 template<typename _Pair, typename = _IFconsp<_Pair>>
1146 __ireturn_type
1147 insert(_Pair&& __v)
1148 {
1149 __hashtable& __h = this->_M_conjure_hashtable();
1150 return __h._M_emplace(__unique_keys{}, std::forward<_Pair>(__v));
1151 }
1152
1153 template<typename _Pair, typename = _IFconsp<_Pair>>
1154 iterator
1155 insert(const_iterator __hint, _Pair&& __v)
1156 {
1157 __hashtable& __h = this->_M_conjure_hashtable();
1158 return __h._M_emplace(__hint, __unique_keys{},
1159 std::forward<_Pair>(__v));
1160 }
1161 };
1162
1163 template<typename _Policy>
1164 using __has_load_factor = typename _Policy::__has_load_factor;
1165
1166 /**
1167 * Primary class template _Rehash_base.
1168 *
1169 * Give hashtable the max_load_factor functions and reserve iff the
1170 * rehash policy supports it.
1171 */
1172 template<typename _Key, typename _Value, typename _Alloc,
1173 typename _ExtractKey, typename _Equal,
1174 typename _Hash, typename _RangeHash, typename _Unused,
1175 typename _RehashPolicy, typename _Traits,
1176 typename =
1177 __detected_or_t<false_type, __has_load_factor, _RehashPolicy>>
1178 struct _Rehash_base;
1179
1180 /// Specialization when rehash policy doesn't provide load factor management.
1181 template<typename _Key, typename _Value, typename _Alloc,
1182 typename _ExtractKey, typename _Equal,
1183 typename _Hash, typename _RangeHash, typename _Unused,
1184 typename _RehashPolicy, typename _Traits>
1185 struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1186 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
1187 false_type /* Has load factor */>
1188 {
1189 };
1190
1191 /// Specialization when rehash policy provide load factor management.
1192 template<typename _Key, typename _Value, typename _Alloc,
1193 typename _ExtractKey, typename _Equal,
1194 typename _Hash, typename _RangeHash, typename _Unused,
1195 typename _RehashPolicy, typename _Traits>
1196 struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1197 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
1198 true_type /* Has load factor */>
1199 {
1200 private:
1201 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
1202 _Equal, _Hash, _RangeHash, _Unused,
1203 _RehashPolicy, _Traits>;
1204
1205 public:
1206 float
1207 max_load_factor() const noexcept
1208 {
1209 const __hashtable* __this = static_cast<const __hashtable*>(this);
1210 return __this->__rehash_policy().max_load_factor();
1211 }
1212
1213 void
1214 max_load_factor(float __z)
1215 {
1216 __hashtable* __this = static_cast<__hashtable*>(this);
1217 __this->__rehash_policy(_RehashPolicy(__z));
1218 }
1219
1220 void
1221 reserve(std::size_t __n)
1222 {
1223 __hashtable* __this = static_cast<__hashtable*>(this);
1224 __this->rehash(__this->__rehash_policy()._M_bkt_for_elements(__n));
1225 }
1226 };
1227
1228 /**
1229 * Primary class template _Hashtable_ebo_helper.
1230 *
1231 * Helper class using EBO when it is not forbidden (the type is not
1232 * final) and when it is worth it (the type is empty.)
1233 */
1234 template<int _Nm, typename _Tp,
1235 bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
1236 struct _Hashtable_ebo_helper;
1237
1238 /// Specialization using EBO.
1239 template<int _Nm, typename _Tp>
1240 struct _Hashtable_ebo_helper<_Nm, _Tp, true>
1241 : private _Tp
1242 {
1243 _Hashtable_ebo_helper() noexcept(noexcept(_Tp())) : _Tp() { }
1244
1245 template<typename _OtherTp>
1246 _Hashtable_ebo_helper(_OtherTp&& __tp)
1247 : _Tp(std::forward<_OtherTp>(__tp))
1248 { }
1249
1250 const _Tp& _M_cget() const { return static_cast<const _Tp&>(*this); }
1251 _Tp& _M_get() { return static_cast<_Tp&>(*this); }
1252 };
1253
1254 /// Specialization not using EBO.
1255 template<int _Nm, typename _Tp>
1256 struct _Hashtable_ebo_helper<_Nm, _Tp, false>
1257 {
1258 _Hashtable_ebo_helper() = default;
1259
1260 template<typename _OtherTp>
1261 _Hashtable_ebo_helper(_OtherTp&& __tp)
1262 : _M_tp(std::forward<_OtherTp>(__tp))
1263 { }
1264
1265 const _Tp& _M_cget() const { return _M_tp; }
1266 _Tp& _M_get() { return _M_tp; }
1267
1268 private:
1269 _Tp _M_tp{};
1270 };
1271
1272 /**
1273 * Primary class template _Local_iterator_base.
1274 *
1275 * Base class for local iterators, used to iterate within a bucket
1276 * but not between buckets.
1277 */
1278 template<typename _Key, typename _Value, typename _ExtractKey,
1279 typename _Hash, typename _RangeHash, typename _Unused,
1280 bool __cache_hash_code>
1281 struct _Local_iterator_base;
1282
1283 /**
1284 * Primary class template _Hash_code_base.
1285 *
1286 * Encapsulates two policy issues that aren't quite orthogonal.
1287 * (1) the difference between using a ranged hash function and using
1288 * the combination of a hash function and a range-hashing function.
1289 * In the former case we don't have such things as hash codes, so
1290 * we have a dummy type as placeholder.
1291 * (2) Whether or not we cache hash codes. Caching hash codes is
1292 * meaningless if we have a ranged hash function.
1293 *
1294 * We also put the key extraction objects here, for convenience.
1295 * Each specialization derives from one or more of the template
1296 * parameters to benefit from Ebo. This is important as this type
1297 * is inherited in some cases by the _Local_iterator_base type used
1298 * to implement local_iterator and const_local_iterator. As with
1299 * any iterator type we prefer to make it as small as possible.
1300 */
1301 template<typename _Key, typename _Value, typename _ExtractKey,
1302 typename _Hash, typename _RangeHash, typename _Unused,
1303 bool __cache_hash_code>
1304 struct _Hash_code_base
1305 : private _Hashtable_ebo_helper<1, _Hash>
1306 {
1307 private:
1308 using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>;
1309
1310 // Gives the local iterator implementation access to _M_bucket_index().
1311 friend struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1312 _Hash, _RangeHash, _Unused, false>;
1313
1314 public:
1315 typedef _Hash hasher;
1316
1317 hasher
1318 hash_function() const
1319 { return _M_hash(); }
1320
1321 protected:
1322 typedef std::size_t __hash_code;
1323
1324 // We need the default constructor for the local iterators and _Hashtable
1325 // default constructor.
1326 _Hash_code_base() = default;
1327
1328 _Hash_code_base(const _Hash& __hash) : __ebo_hash(__hash) { }
1329
1330 __hash_code
1331 _M_hash_code(const _Key& __k) const
1332 {
1333 static_assert(__is_invocable<const _Hash&, const _Key&>{},
1334 "hash function must be invocable with an argument of key type");
1335 return _M_hash()(__k);
1336 }
1337
1338 template<typename _Kt>
1339 __hash_code
1340 _M_hash_code_tr(const _Kt& __k) const
1341 {
1342 static_assert(__is_invocable<const _Hash&, const _Kt&>{},
1343 "hash function must be invocable with an argument of key type");
1344 return _M_hash()(__k);
1345 }
1346
1347 __hash_code
1348 _M_hash_code(const _Hash_node_value<_Value, false>& __n) const
1349 { return _M_hash_code(_ExtractKey{}(__n._M_v())); }
1350
1351 __hash_code
1352 _M_hash_code(const _Hash_node_value<_Value, true>& __n) const
1353 { return __n._M_hash_code; }
1354
1355 std::size_t
1356 _M_bucket_index(__hash_code __c, std::size_t __bkt_count) const
1357 { return _RangeHash{}(__c, __bkt_count); }
1358
1359 std::size_t
1360 _M_bucket_index(const _Hash_node_value<_Value, false>& __n,
1361 std::size_t __bkt_count) const
1362 noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>()))
1363 && noexcept(declval<const _RangeHash&>()((__hash_code)0,
1364 (std::size_t)0)) )
1365 {
1366 return _RangeHash{}(_M_hash_code(_ExtractKey{}(__n._M_v())),
1367 __bkt_count);
1368 }
1369
1370 std::size_t
1371 _M_bucket_index(const _Hash_node_value<_Value, true>& __n,
1372 std::size_t __bkt_count) const
1373 noexcept( noexcept(declval<const _RangeHash&>()((__hash_code)0,
1374 (std::size_t)0)) )
1375 { return _RangeHash{}(__n._M_hash_code, __bkt_count); }
1376
1377 void
1378 _M_store_code(_Hash_node_code_cache<false>&, __hash_code) const
1379 { }
1380
1381 void
1382 _M_copy_code(_Hash_node_code_cache<false>&,
1383 const _Hash_node_code_cache<false>&) const
1384 { }
1385
1386 void
1387 _M_store_code(_Hash_node_code_cache<true>& __n, __hash_code __c) const
1388 { __n._M_hash_code = __c; }
1389
1390 void
1391 _M_copy_code(_Hash_node_code_cache<true>& __to,
1392 const _Hash_node_code_cache<true>& __from) const
1393 { __to._M_hash_code = __from._M_hash_code; }
1394
1395 void
1396 _M_swap(_Hash_code_base& __x)
1397 { std::swap(__ebo_hash::_M_get(), __x.__ebo_hash::_M_get()); }
1398
1399 const _Hash&
1400 _M_hash() const { return __ebo_hash::_M_cget(); }
1401 };
1402
1403 /// Partial specialization used when nodes contain a cached hash code.
1404 template<typename _Key, typename _Value, typename _ExtractKey,
1405 typename _Hash, typename _RangeHash, typename _Unused>
1406 struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1407 _Hash, _RangeHash, _Unused, true>
1408 : public _Node_iterator_base<_Value, true>
1409 {
1410 protected:
1411 using __base_node_iter = _Node_iterator_base<_Value, true>;
1412 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1413 _Hash, _RangeHash, _Unused, true>;
1414
1415 _Local_iterator_base() = default;
1416 _Local_iterator_base(const __hash_code_base&,
1417 _Hash_node<_Value, true>* __p,
1418 std::size_t __bkt, std::size_t __bkt_count)
1419 : __base_node_iter(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1420 { }
1421
1422 void
1423 _M_incr()
1424 {
1425 __base_node_iter::_M_incr();
1426 if (this->_M_cur)
1427 {
1428 std::size_t __bkt
1429 = _RangeHash{}(this->_M_cur->_M_hash_code, _M_bucket_count);
1430 if (__bkt != _M_bucket)
1431 this->_M_cur = nullptr;
1432 }
1433 }
1434
1435 std::size_t _M_bucket;
1436 std::size_t _M_bucket_count;
1437
1438 public:
1439 std::size_t
1440 _M_get_bucket() const { return _M_bucket; } // for debug mode
1441 };
1442
1443 // Uninitialized storage for a _Hash_code_base.
1444 // This type is DefaultConstructible and Assignable even if the
1445 // _Hash_code_base type isn't, so that _Local_iterator_base<..., false>
1446 // can be DefaultConstructible and Assignable.
1447 template<typename _Tp, bool _IsEmpty = std::is_empty<_Tp>::value>
1448 struct _Hash_code_storage
1449 {
1450 __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
1451
1452 _Tp*
1453 _M_h() { return _M_storage._M_ptr(); }
1454
1455 const _Tp*
1456 _M_h() const { return _M_storage._M_ptr(); }
1457 };
1458
1459 // Empty partial specialization for empty _Hash_code_base types.
1460 template<typename _Tp>
1461 struct _Hash_code_storage<_Tp, true>
1462 {
1463 static_assert( std::is_empty<_Tp>::value, "Type must be empty" );
1464
1465 // As _Tp is an empty type there will be no bytes written/read through
1466 // the cast pointer, so no strict-aliasing violation.
1467 _Tp*
1468 _M_h() { return reinterpret_cast<_Tp*>(this); }
1469
1470 const _Tp*
1471 _M_h() const { return reinterpret_cast<const _Tp*>(this); }
1472 };
1473
1474 template<typename _Key, typename _Value, typename _ExtractKey,
1475 typename _Hash, typename _RangeHash, typename _Unused>
1476 using __hash_code_for_local_iter
1477 = _Hash_code_storage<_Hash_code_base<_Key, _Value, _ExtractKey,
1478 _Hash, _RangeHash, _Unused, false>>;
1479
1480 // Partial specialization used when hash codes are not cached
1481 template<typename _Key, typename _Value, typename _ExtractKey,
1482 typename _Hash, typename _RangeHash, typename _Unused>
1483 struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1484 _Hash, _RangeHash, _Unused, false>
1485 : __hash_code_for_local_iter<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1486 _Unused>
1487 , _Node_iterator_base<_Value, false>
1488 {
1489 protected:
1490 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1491 _Hash, _RangeHash, _Unused, false>;
1492 using __node_iter_base = _Node_iterator_base<_Value, false>;
1493
1494 _Local_iterator_base() : _M_bucket_count(-1) { }
1495
1496 _Local_iterator_base(const __hash_code_base& __base,
1497 _Hash_node<_Value, false>* __p,
1498 std::size_t __bkt, std::size_t __bkt_count)
1499 : __node_iter_base(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1500 { _M_init(__base); }
1501
1502 ~_Local_iterator_base()
1503 {
1504 if (_M_bucket_count != size_t(-1))
1505 _M_destroy();
1506 }
1507
1508 _Local_iterator_base(const _Local_iterator_base& __iter)
1509 : __node_iter_base(__iter._M_cur), _M_bucket(__iter._M_bucket)
1510 , _M_bucket_count(__iter._M_bucket_count)
1511 {
1512 if (_M_bucket_count != size_t(-1))
1513 _M_init(base: *__iter._M_h());
1514 }
1515
1516 _Local_iterator_base&
1517 operator=(const _Local_iterator_base& __iter)
1518 {
1519 if (_M_bucket_count != -1)
1520 _M_destroy();
1521 this->_M_cur = __iter._M_cur;
1522 _M_bucket = __iter._M_bucket;
1523 _M_bucket_count = __iter._M_bucket_count;
1524 if (_M_bucket_count != -1)
1525 _M_init(base: *__iter._M_h());
1526 return *this;
1527 }
1528
1529 void
1530 _M_incr()
1531 {
1532 __node_iter_base::_M_incr();
1533 if (this->_M_cur)
1534 {
1535 std::size_t __bkt = this->_M_h()->_M_bucket_index(*this->_M_cur,
1536 _M_bucket_count);
1537 if (__bkt != _M_bucket)
1538 this->_M_cur = nullptr;
1539 }
1540 }
1541
1542 std::size_t _M_bucket;
1543 std::size_t _M_bucket_count;
1544
1545 void
1546 _M_init(const __hash_code_base& __base)
1547 { ::new(this->_M_h()) __hash_code_base(__base); }
1548
1549 void
1550 _M_destroy() { this->_M_h()->~__hash_code_base(); }
1551
1552 public:
1553 std::size_t
1554 _M_get_bucket() const { return _M_bucket; } // for debug mode
1555 };
1556
1557 /// local iterators
1558 template<typename _Key, typename _Value, typename _ExtractKey,
1559 typename _Hash, typename _RangeHash, typename _Unused,
1560 bool __constant_iterators, bool __cache>
1561 struct _Local_iterator
1562 : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1563 _Hash, _RangeHash, _Unused, __cache>
1564 {
1565 private:
1566 using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1567 _Hash, _RangeHash, _Unused, __cache>;
1568 using __hash_code_base = typename __base_type::__hash_code_base;
1569
1570 public:
1571 using value_type = _Value;
1572 using pointer = __conditional_t<__constant_iterators,
1573 const value_type*, value_type*>;
1574 using reference = __conditional_t<__constant_iterators,
1575 const value_type&, value_type&>;
1576 using difference_type = ptrdiff_t;
1577 using iterator_category = forward_iterator_tag;
1578
1579 _Local_iterator() = default;
1580
1581 _Local_iterator(const __hash_code_base& __base,
1582 _Hash_node<_Value, __cache>* __n,
1583 std::size_t __bkt, std::size_t __bkt_count)
1584 : __base_type(__base, __n, __bkt, __bkt_count)
1585 { }
1586
1587 reference
1588 operator*() const
1589 { return this->_M_cur->_M_v(); }
1590
1591 pointer
1592 operator->() const
1593 { return this->_M_cur->_M_valptr(); }
1594
1595 _Local_iterator&
1596 operator++()
1597 {
1598 this->_M_incr();
1599 return *this;
1600 }
1601
1602 _Local_iterator
1603 operator++(int)
1604 {
1605 _Local_iterator __tmp(*this);
1606 this->_M_incr();
1607 return __tmp;
1608 }
1609 };
1610
1611 /// local const_iterators
1612 template<typename _Key, typename _Value, typename _ExtractKey,
1613 typename _Hash, typename _RangeHash, typename _Unused,
1614 bool __constant_iterators, bool __cache>
1615 struct _Local_const_iterator
1616 : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1617 _Hash, _RangeHash, _Unused, __cache>
1618 {
1619 private:
1620 using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1621 _Hash, _RangeHash, _Unused, __cache>;
1622 using __hash_code_base = typename __base_type::__hash_code_base;
1623
1624 public:
1625 typedef _Value value_type;
1626 typedef const value_type* pointer;
1627 typedef const value_type& reference;
1628 typedef std::ptrdiff_t difference_type;
1629 typedef std::forward_iterator_tag iterator_category;
1630
1631 _Local_const_iterator() = default;
1632
1633 _Local_const_iterator(const __hash_code_base& __base,
1634 _Hash_node<_Value, __cache>* __n,
1635 std::size_t __bkt, std::size_t __bkt_count)
1636 : __base_type(__base, __n, __bkt, __bkt_count)
1637 { }
1638
1639 _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
1640 _Hash, _RangeHash, _Unused,
1641 __constant_iterators,
1642 __cache>& __x)
1643 : __base_type(__x)
1644 { }
1645
1646 reference
1647 operator*() const
1648 { return this->_M_cur->_M_v(); }
1649
1650 pointer
1651 operator->() const
1652 { return this->_M_cur->_M_valptr(); }
1653
1654 _Local_const_iterator&
1655 operator++()
1656 {
1657 this->_M_incr();
1658 return *this;
1659 }
1660
1661 _Local_const_iterator
1662 operator++(int)
1663 {
1664 _Local_const_iterator __tmp(*this);
1665 this->_M_incr();
1666 return __tmp;
1667 }
1668 };
1669
1670 /**
1671 * Primary class template _Hashtable_base.
1672 *
1673 * Helper class adding management of _Equal functor to
1674 * _Hash_code_base type.
1675 *
1676 * Base class templates are:
1677 * - __detail::_Hash_code_base
1678 * - __detail::_Hashtable_ebo_helper
1679 */
1680 template<typename _Key, typename _Value, typename _ExtractKey,
1681 typename _Equal, typename _Hash, typename _RangeHash,
1682 typename _Unused, typename _Traits>
1683 struct _Hashtable_base
1684 : public _Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1685 _Unused, _Traits::__hash_cached::value>,
1686 private _Hashtable_ebo_helper<0, _Equal>
1687 {
1688 public:
1689 typedef _Key key_type;
1690 typedef _Value value_type;
1691 typedef _Equal key_equal;
1692 typedef std::size_t size_type;
1693 typedef std::ptrdiff_t difference_type;
1694
1695 using __traits_type = _Traits;
1696 using __hash_cached = typename __traits_type::__hash_cached;
1697
1698 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1699 _Hash, _RangeHash, _Unused,
1700 __hash_cached::value>;
1701
1702 using __hash_code = typename __hash_code_base::__hash_code;
1703
1704 private:
1705 using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>;
1706
1707 static bool
1708 _S_equals(__hash_code, const _Hash_node_code_cache<false>&)
1709 { return true; }
1710
1711 static bool
1712 _S_node_equals(const _Hash_node_code_cache<false>&,
1713 const _Hash_node_code_cache<false>&)
1714 { return true; }
1715
1716 static bool
1717 _S_equals(__hash_code __c, const _Hash_node_code_cache<true>& __n)
1718 { return __c == __n._M_hash_code; }
1719
1720 static bool
1721 _S_node_equals(const _Hash_node_code_cache<true>& __lhn,
1722 const _Hash_node_code_cache<true>& __rhn)
1723 { return __lhn._M_hash_code == __rhn._M_hash_code; }
1724
1725 protected:
1726 _Hashtable_base() = default;
1727
1728 _Hashtable_base(const _Hash& __hash, const _Equal& __eq)
1729 : __hash_code_base(__hash), _EqualEBO(__eq)
1730 { }
1731
1732 bool
1733 _M_key_equals(const _Key& __k,
1734 const _Hash_node_value<_Value,
1735 __hash_cached::value>& __n) const
1736 {
1737 static_assert(__is_invocable<const _Equal&, const _Key&, const _Key&>{},
1738 "key equality predicate must be invocable with two arguments of "
1739 "key type");
1740 return _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1741 }
1742
1743 template<typename _Kt>
1744 bool
1745 _M_key_equals_tr(const _Kt& __k,
1746 const _Hash_node_value<_Value,
1747 __hash_cached::value>& __n) const
1748 {
1749 static_assert(
1750 __is_invocable<const _Equal&, const _Kt&, const _Key&>{},
1751 "key equality predicate must be invocable with two arguments of "
1752 "key type");
1753 return _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1754 }
1755
1756 bool
1757 _M_equals(const _Key& __k, __hash_code __c,
1758 const _Hash_node_value<_Value, __hash_cached::value>& __n) const
1759 { return _S_equals(__c, __n) && _M_key_equals(__k, __n); }
1760
1761 template<typename _Kt>
1762 bool
1763 _M_equals_tr(const _Kt& __k, __hash_code __c,
1764 const _Hash_node_value<_Value,
1765 __hash_cached::value>& __n) const
1766 { return _S_equals(__c, __n) && _M_key_equals_tr(__k, __n); }
1767
1768 bool
1769 _M_node_equals(
1770 const _Hash_node_value<_Value, __hash_cached::value>& __lhn,
1771 const _Hash_node_value<_Value, __hash_cached::value>& __rhn) const
1772 {
1773 return _S_node_equals(__lhn, __rhn)
1774 && _M_key_equals(k: _ExtractKey{}(__lhn._M_v()), n: __rhn);
1775 }
1776
1777 void
1778 _M_swap(_Hashtable_base& __x)
1779 {
1780 __hash_code_base::_M_swap(__x);
1781 std::swap(_EqualEBO::_M_get(), __x._EqualEBO::_M_get());
1782 }
1783
1784 const _Equal&
1785 _M_eq() const { return _EqualEBO::_M_cget(); }
1786 };
1787
1788 /**
1789 * Primary class template _Equality.
1790 *
1791 * This is for implementing equality comparison for unordered
1792 * containers, per N3068, by John Lakos and Pablo Halpern.
1793 * Algorithmically, we follow closely the reference implementations
1794 * therein.
1795 */
1796 template<typename _Key, typename _Value, typename _Alloc,
1797 typename _ExtractKey, typename _Equal,
1798 typename _Hash, typename _RangeHash, typename _Unused,
1799 typename _RehashPolicy, typename _Traits,
1800 bool _Unique_keys = _Traits::__unique_keys::value>
1801 struct _Equality;
1802
1803 /// unordered_map and unordered_set specializations.
1804 template<typename _Key, typename _Value, typename _Alloc,
1805 typename _ExtractKey, typename _Equal,
1806 typename _Hash, typename _RangeHash, typename _Unused,
1807 typename _RehashPolicy, typename _Traits>
1808 struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1809 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
1810 {
1811 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1812 _Hash, _RangeHash, _Unused,
1813 _RehashPolicy, _Traits>;
1814
1815 bool
1816 _M_equal(const __hashtable&) const;
1817 };
1818
1819 template<typename _Key, typename _Value, typename _Alloc,
1820 typename _ExtractKey, typename _Equal,
1821 typename _Hash, typename _RangeHash, typename _Unused,
1822 typename _RehashPolicy, typename _Traits>
1823 bool
1824 _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1825 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
1826 _M_equal(const __hashtable& __other) const
1827 {
1828 using __node_ptr = typename __hashtable::__node_ptr;
1829 const __hashtable* __this = static_cast<const __hashtable*>(this);
1830 if (__this->size() != __other.size())
1831 return false;
1832
1833 for (auto __x_n = __this->_M_begin(); __x_n; __x_n = __x_n->_M_next())
1834 {
1835 std::size_t __ybkt = __other._M_bucket_index(*__x_n);
1836 auto __prev_n = __other._M_buckets[__ybkt];
1837 if (!__prev_n)
1838 return false;
1839
1840 for (__node_ptr __n = static_cast<__node_ptr>(__prev_n->_M_nxt);;
1841 __n = __n->_M_next())
1842 {
1843 if (__n->_M_v() == __x_n->_M_v())
1844 break;
1845
1846 if (!__n->_M_nxt
1847 || __other._M_bucket_index(*__n->_M_next()) != __ybkt)
1848 return false;
1849 }
1850 }
1851
1852 return true;
1853 }
1854
1855 /// unordered_multiset and unordered_multimap specializations.
1856 template<typename _Key, typename _Value, typename _Alloc,
1857 typename _ExtractKey, typename _Equal,
1858 typename _Hash, typename _RangeHash, typename _Unused,
1859 typename _RehashPolicy, typename _Traits>
1860 struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1861 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
1862 {
1863 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1864 _Hash, _RangeHash, _Unused,
1865 _RehashPolicy, _Traits>;
1866
1867 bool
1868 _M_equal(const __hashtable&) const;
1869 };
1870
1871 template<typename _Key, typename _Value, typename _Alloc,
1872 typename _ExtractKey, typename _Equal,
1873 typename _Hash, typename _RangeHash, typename _Unused,
1874 typename _RehashPolicy, typename _Traits>
1875 bool
1876 _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1877 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>::
1878 _M_equal(const __hashtable& __other) const
1879 {
1880 using __node_ptr = typename __hashtable::__node_ptr;
1881 using const_iterator = typename __hashtable::const_iterator;
1882 const __hashtable* __this = static_cast<const __hashtable*>(this);
1883 if (__this->size() != __other.size())
1884 return false;
1885
1886 for (auto __x_n = __this->_M_begin(); __x_n;)
1887 {
1888 std::size_t __x_count = 1;
1889 auto __x_n_end = __x_n->_M_next();
1890 for (; __x_n_end
1891 && __this->key_eq()(_ExtractKey{}(__x_n->_M_v()),
1892 _ExtractKey{}(__x_n_end->_M_v()));
1893 __x_n_end = __x_n_end->_M_next())
1894 ++__x_count;
1895
1896 std::size_t __ybkt = __other._M_bucket_index(*__x_n);
1897 auto __y_prev_n = __other._M_buckets[__ybkt];
1898 if (!__y_prev_n)
1899 return false;
1900
1901 __node_ptr __y_n = static_cast<__node_ptr>(__y_prev_n->_M_nxt);
1902 for (;;)
1903 {
1904 if (__this->key_eq()(_ExtractKey{}(__y_n->_M_v()),
1905 _ExtractKey{}(__x_n->_M_v())))
1906 break;
1907
1908 auto __y_ref_n = __y_n;
1909 for (__y_n = __y_n->_M_next(); __y_n; __y_n = __y_n->_M_next())
1910 if (!__other._M_node_equals(*__y_ref_n, *__y_n))
1911 break;
1912
1913 if (!__y_n || __other._M_bucket_index(*__y_n) != __ybkt)
1914 return false;
1915 }
1916
1917 auto __y_n_end = __y_n;
1918 for (; __y_n_end; __y_n_end = __y_n_end->_M_next())
1919 if (--__x_count == 0)
1920 break;
1921
1922 if (__x_count != 0)
1923 return false;
1924
1925 const_iterator __itx(__x_n), __itx_end(__x_n_end);
1926 const_iterator __ity(__y_n);
1927 if (!std::is_permutation(__itx, __itx_end, __ity))
1928 return false;
1929
1930 __x_n = __x_n_end;
1931 }
1932 return true;
1933 }
1934
1935 /**
1936 * This type deals with all allocation and keeps an allocator instance
1937 * through inheritance to benefit from EBO when possible.
1938 */
1939 template<typename _NodeAlloc>
1940 struct _Hashtable_alloc : private _Hashtable_ebo_helper<0, _NodeAlloc>
1941 {
1942 private:
1943 using __ebo_node_alloc = _Hashtable_ebo_helper<0, _NodeAlloc>;
1944
1945 template<typename>
1946 struct __get_value_type;
1947 template<typename _Val, bool _Cache_hash_code>
1948 struct __get_value_type<_Hash_node<_Val, _Cache_hash_code>>
1949 { using type = _Val; };
1950
1951 public:
1952 using __node_type = typename _NodeAlloc::value_type;
1953 using __node_alloc_type = _NodeAlloc;
1954 // Use __gnu_cxx to benefit from _S_always_equal and al.
1955 using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
1956
1957 using __value_alloc_traits = typename __node_alloc_traits::template
1958 rebind_traits<typename __get_value_type<__node_type>::type>;
1959
1960 using __node_ptr = __node_type*;
1961 using __node_base = _Hash_node_base;
1962 using __node_base_ptr = __node_base*;
1963 using __buckets_alloc_type =
1964 __alloc_rebind<__node_alloc_type, __node_base_ptr>;
1965 using __buckets_alloc_traits = std::allocator_traits<__buckets_alloc_type>;
1966 using __buckets_ptr = __node_base_ptr*;
1967
1968 _Hashtable_alloc() = default;
1969 _Hashtable_alloc(const _Hashtable_alloc&) = default;
1970 _Hashtable_alloc(_Hashtable_alloc&&) = default;
1971
1972 template<typename _Alloc>
1973 _Hashtable_alloc(_Alloc&& __a)
1974 : __ebo_node_alloc(std::forward<_Alloc>(__a))
1975 { }
1976
1977 __node_alloc_type&
1978 _M_node_allocator()
1979 { return __ebo_node_alloc::_M_get(); }
1980
1981 const __node_alloc_type&
1982 _M_node_allocator() const
1983 { return __ebo_node_alloc::_M_cget(); }
1984
1985 // Allocate a node and construct an element within it.
1986 template<typename... _Args>
1987 __node_ptr
1988 _M_allocate_node(_Args&&... __args);
1989
1990 // Destroy the element within a node and deallocate the node.
1991 void
1992 _M_deallocate_node(__node_ptr __n);
1993
1994 // Deallocate a node.
1995 void
1996 _M_deallocate_node_ptr(__node_ptr __n);
1997
1998 // Deallocate the linked list of nodes pointed to by __n.
1999 // The elements within the nodes are destroyed.
2000 void
2001 _M_deallocate_nodes(__node_ptr __n);
2002
2003 __buckets_ptr
2004 _M_allocate_buckets(std::size_t __bkt_count);
2005
2006 void
2007 _M_deallocate_buckets(__buckets_ptr, std::size_t __bkt_count);
2008 };
2009
2010 // Definitions of class template _Hashtable_alloc's out-of-line member
2011 // functions.
2012 template<typename _NodeAlloc>
2013 template<typename... _Args>
2014 auto
2015 _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
2016 -> __node_ptr
2017 {
2018 auto& __alloc = _M_node_allocator();
2019 auto __nptr = __node_alloc_traits::allocate(__alloc, 1);
2020 __node_ptr __n = std::__to_address(__nptr);
2021 __try
2022 {
2023 ::new ((void*)__n) __node_type;
2024 __node_alloc_traits::construct(__alloc, __n->_M_valptr(),
2025 std::forward<_Args>(__args)...);
2026 return __n;
2027 }
2028 __catch(...)
2029 {
2030 __n->~__node_type();
2031 __node_alloc_traits::deallocate(__alloc, __nptr, 1);
2032 __throw_exception_again;
2033 }
2034 }
2035
2036 template<typename _NodeAlloc>
2037 void
2038 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_ptr __n)
2039 {
2040 __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
2041 _M_deallocate_node_ptr(__n);
2042 }
2043
2044 template<typename _NodeAlloc>
2045 void
2046 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node_ptr(__node_ptr __n)
2047 {
2048 typedef typename __node_alloc_traits::pointer _Ptr;
2049 auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
2050 __n->~__node_type();
2051 __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
2052 }
2053
2054 template<typename _NodeAlloc>
2055 void
2056 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_ptr __n)
2057 {
2058 while (__n)
2059 {
2060 __node_ptr __tmp = __n;
2061 __n = __n->_M_next();
2062 _M_deallocate_node(n: __tmp);
2063 }
2064 }
2065
2066 template<typename _NodeAlloc>
2067 auto
2068 _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(std::size_t __bkt_count)
2069 -> __buckets_ptr
2070 {
2071 __buckets_alloc_type __alloc(_M_node_allocator());
2072
2073 auto __ptr = __buckets_alloc_traits::allocate(__alloc, __bkt_count);
2074 __buckets_ptr __p = std::__to_address(__ptr);
2075 __builtin_memset(__p, 0, __bkt_count * sizeof(__node_base_ptr));
2076 return __p;
2077 }
2078
2079 template<typename _NodeAlloc>
2080 void
2081 _Hashtable_alloc<_NodeAlloc>::
2082 _M_deallocate_buckets(__buckets_ptr __bkts,
2083 std::size_t __bkt_count)
2084 {
2085 typedef typename __buckets_alloc_traits::pointer _Ptr;
2086 auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
2087 __buckets_alloc_type __alloc(_M_node_allocator());
2088 __buckets_alloc_traits::deallocate(__alloc, __ptr, __bkt_count);
2089 }
2090
2091 ///@} hashtable-detail
2092} // namespace __detail
2093/// @endcond
2094_GLIBCXX_END_NAMESPACE_VERSION
2095} // namespace std
2096
2097#endif // _HASHTABLE_POLICY_H
2098