libstdc++
hashtable_policy.h
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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>
69 __distance_fw(_Iterator __first, _Iterator __last,
71 { return __first != __last ? 1 : 0; }
72
73 template<typename _Iterator>
75 __distance_fw(_Iterator __first, _Iterator __last,
77 { return std::distance(__first, __last); }
78
79 template<typename _Iterator>
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#if __cpp_impl_three_way_comparison >= 201907L
469 friend bool
470 operator==(const _Node_iterator&, const _Node_iterator&) = default;
471#else
472 friend bool
473 operator==(const _Node_iterator& __x, const _Node_iterator& __y) noexcept
474 {
475 const __base_type& __bx = __x;
476 const __base_type& __by = __y;
477 return __bx == __by;
478 }
479
480 friend bool
481 operator!=(const _Node_iterator& __x, const _Node_iterator& __y) noexcept
482 { return !(__x == __y); }
483#endif
484 };
485
486 /// Node const_iterators, used to iterate through all the hashtable.
487 template<typename _Value, bool __constant_iterators, bool __cache>
488 struct _Node_const_iterator
489 : public _Node_iterator_base<_Value, __cache>
490 {
491 private:
492 using __base_type = _Node_iterator_base<_Value, __cache>;
493 using __node_type = typename __base_type::__node_type;
494
495 // The corresponding non-const iterator.
496 using __iterator
497 = _Node_iterator<_Value, __constant_iterators, __cache>;
498
499 public:
500 typedef _Value value_type;
501 typedef std::ptrdiff_t difference_type;
502 typedef std::forward_iterator_tag iterator_category;
503
504 typedef const value_type* pointer;
505 typedef const value_type& reference;
506
507 _Node_const_iterator() = default;
508
509 explicit
510 _Node_const_iterator(__node_type* __p) noexcept
511 : __base_type(__p) { }
512
513 _Node_const_iterator(const __iterator& __x) noexcept
514 : __base_type(__x._M_cur) { }
515
516 reference
517 operator*() const noexcept
518 { return this->_M_cur->_M_v(); }
519
520 pointer
521 operator->() const noexcept
522 { return this->_M_cur->_M_valptr(); }
523
524 _Node_const_iterator&
525 operator++() noexcept
526 {
527 this->_M_incr();
528 return *this;
529 }
530
531 _Node_const_iterator
532 operator++(int) noexcept
533 {
534 _Node_const_iterator __tmp(*this);
535 this->_M_incr();
536 return __tmp;
537 }
538
539#if __cpp_impl_three_way_comparison >= 201907L
540 friend bool
541 operator==(const _Node_const_iterator&,
542 const _Node_const_iterator&) = default;
543
544 friend bool
545 operator==(const _Node_const_iterator& __x, const __iterator& __y)
546 {
547 const __base_type& __bx = __x;
548 const __base_type& __by = __y;
549 return __bx == __by;
550 }
551#else
552 friend bool
553 operator==(const _Node_const_iterator& __x,
554 const _Node_const_iterator& __y) noexcept
555 {
556 const __base_type& __bx = __x;
557 const __base_type& __by = __y;
558 return __bx == __by;
559 }
560
561 friend bool
562 operator!=(const _Node_const_iterator& __x,
563 const _Node_const_iterator& __y) noexcept
564 { return !(__x == __y); }
565
566 friend bool
567 operator==(const _Node_const_iterator& __x,
568 const __iterator& __y) noexcept
569 {
570 const __base_type& __bx = __x;
571 const __base_type& __by = __y;
572 return __bx == __by;
573 }
574
575 friend bool
576 operator!=(const _Node_const_iterator& __x,
577 const __iterator& __y) noexcept
578 { return !(__x == __y); }
579
580 friend bool
581 operator==(const __iterator& __x,
582 const _Node_const_iterator& __y) noexcept
583 {
584 const __base_type& __bx = __x;
585 const __base_type& __by = __y;
586 return __bx == __by;
587 }
588
589 friend bool
590 operator!=(const __iterator& __x,
591 const _Node_const_iterator& __y) noexcept
592 { return !(__x == __y); }
593#endif
594 };
595
596 // Many of class template _Hashtable's template parameters are policy
597 // classes. These are defaults for the policies.
598
599 /// Default range hashing function: use division to fold a large number
600 /// into the range [0, N).
601 struct _Mod_range_hashing
602 {
603 typedef std::size_t first_argument_type;
604 typedef std::size_t second_argument_type;
605 typedef std::size_t result_type;
606
607 result_type
608 operator()(first_argument_type __num,
609 second_argument_type __den) const noexcept
610 { return __num % __den; }
611 };
612
613 /// Default ranged hash function H. In principle it should be a
614 /// function object composed from objects of type H1 and H2 such that
615 /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
616 /// h1 and h2. So instead we'll just use a tag to tell class template
617 /// hashtable to do that composition.
618 struct _Default_ranged_hash { };
619
620 /// Default value for rehash policy. Bucket size is (usually) the
621 /// smallest prime that keeps the load factor small enough.
622 struct _Prime_rehash_policy
623 {
624 using __has_load_factor = true_type;
625
626 _Prime_rehash_policy(float __z = 1.0) noexcept
627 : _M_max_load_factor(__z), _M_next_resize(0) { }
628
629 float
630 max_load_factor() const noexcept
631 { return _M_max_load_factor; }
632
633 // Return a bucket size no smaller than n.
634 std::size_t
635 _M_next_bkt(std::size_t __n) const;
636
637 // Return a bucket count appropriate for n elements
638 std::size_t
639 _M_bkt_for_elements(std::size_t __n) const
640 { return __builtin_ceil(__n / (double)_M_max_load_factor); }
641
642 // __n_bkt is current bucket count, __n_elt is current element count,
643 // and __n_ins is number of elements to be inserted. Do we need to
644 // increase bucket count? If so, return make_pair(true, n), where n
645 // is the new bucket count. If not, return make_pair(false, 0).
647 _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
648 std::size_t __n_ins) const;
649
650 typedef std::size_t _State;
651
652 _State
653 _M_state() const
654 { return _M_next_resize; }
655
656 void
657 _M_reset() noexcept
658 { _M_next_resize = 0; }
659
660 void
661 _M_reset(_State __state)
662 { _M_next_resize = __state; }
663
664 static const std::size_t _S_growth_factor = 2;
665
666 float _M_max_load_factor;
667 mutable std::size_t _M_next_resize;
668 };
669
670 /// Range hashing function assuming that second arg is a power of 2.
671 struct _Mask_range_hashing
672 {
673 typedef std::size_t first_argument_type;
674 typedef std::size_t second_argument_type;
675 typedef std::size_t result_type;
676
677 result_type
678 operator()(first_argument_type __num,
679 second_argument_type __den) const noexcept
680 { return __num & (__den - 1); }
681 };
682
683 /// Compute closest power of 2 not less than __n
684 inline std::size_t
685 __clp2(std::size_t __n) noexcept
686 {
688 // Equivalent to return __n ? std::bit_ceil(__n) : 0;
689 if (__n < 2)
690 return __n;
691 const unsigned __lz = sizeof(size_t) > sizeof(long)
692 ? __builtin_clzll(__n - 1ull)
693 : __builtin_clzl(__n - 1ul);
694 // Doing two shifts avoids undefined behaviour when __lz == 0.
695 return (size_t(1) << (__int_traits<size_t>::__digits - __lz - 1)) << 1;
696 }
697
698 /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
699 /// operations.
700 struct _Power2_rehash_policy
701 {
702 using __has_load_factor = true_type;
703
704 _Power2_rehash_policy(float __z = 1.0) noexcept
705 : _M_max_load_factor(__z), _M_next_resize(0) { }
706
707 float
708 max_load_factor() const noexcept
709 { return _M_max_load_factor; }
710
711 // Return a bucket size no smaller than n (as long as n is not above the
712 // highest power of 2).
713 std::size_t
714 _M_next_bkt(std::size_t __n) noexcept
715 {
716 if (__n == 0)
717 // Special case on container 1st initialization with 0 bucket count
718 // hint. We keep _M_next_resize to 0 to make sure that next time we
719 // want to add an element allocation will take place.
720 return 1;
721
722 const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
723 const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
724 std::size_t __res = __clp2(__n);
725
726 if (__res == 0)
727 __res = __max_bkt;
728 else if (__res == 1)
729 // If __res is 1 we force it to 2 to make sure there will be an
730 // allocation so that nothing need to be stored in the initial
731 // single bucket
732 __res = 2;
733
734 if (__res == __max_bkt)
735 // Set next resize to the max value so that we never try to rehash again
736 // as we already reach the biggest possible bucket number.
737 // Note that it might result in max_load_factor not being respected.
738 _M_next_resize = size_t(-1);
739 else
740 _M_next_resize
741 = __builtin_floor(__res * (double)_M_max_load_factor);
742
743 return __res;
744 }
745
746 // Return a bucket count appropriate for n elements
747 std::size_t
748 _M_bkt_for_elements(std::size_t __n) const noexcept
749 { return __builtin_ceil(__n / (double)_M_max_load_factor); }
750
751 // __n_bkt is current bucket count, __n_elt is current element count,
752 // and __n_ins is number of elements to be inserted. Do we need to
753 // increase bucket count? If so, return make_pair(true, n), where n
754 // is the new bucket count. If not, return make_pair(false, 0).
756 _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
757 std::size_t __n_ins) noexcept
758 {
759 if (__n_elt + __n_ins > _M_next_resize)
760 {
761 // If _M_next_resize is 0 it means that we have nothing allocated so
762 // far and that we start inserting elements. In this case we start
763 // with an initial bucket size of 11.
764 double __min_bkts
765 = std::max<std::size_t>(__n_elt + __n_ins, _M_next_resize ? 0 : 11)
766 / (double)_M_max_load_factor;
767 if (__min_bkts >= __n_bkt)
768 return { true,
769 _M_next_bkt(std::max<std::size_t>(__builtin_floor(__min_bkts) + 1,
770 __n_bkt * _S_growth_factor)) };
771
772 _M_next_resize
773 = __builtin_floor(__n_bkt * (double)_M_max_load_factor);
774 return { false, 0 };
775 }
776 else
777 return { false, 0 };
778 }
779
780 typedef std::size_t _State;
781
782 _State
783 _M_state() const noexcept
784 { return _M_next_resize; }
785
786 void
787 _M_reset() noexcept
788 { _M_next_resize = 0; }
789
790 void
791 _M_reset(_State __state) noexcept
792 { _M_next_resize = __state; }
793
794 static const std::size_t _S_growth_factor = 2;
795
796 float _M_max_load_factor;
797 std::size_t _M_next_resize;
798 };
799
800 template<typename _RehashPolicy>
801 struct _RehashStateGuard
802 {
803 _RehashPolicy* _M_guarded_obj;
804 typename _RehashPolicy::_State _M_prev_state;
805
806 _RehashStateGuard(_RehashPolicy& __policy)
807 : _M_guarded_obj(std::__addressof(__policy))
808 , _M_prev_state(__policy._M_state())
809 { }
810 _RehashStateGuard(const _RehashStateGuard&) = delete;
811
812 ~_RehashStateGuard()
813 {
814 if (_M_guarded_obj)
815 _M_guarded_obj->_M_reset(_M_prev_state);
816 }
817 };
818
819 // Base classes for std::_Hashtable. We define these base classes
820 // because in some cases we want to do different things depending on
821 // the value of a policy class. In some cases the policy class
822 // affects which member functions and nested typedefs are defined;
823 // we handle that by specializing base class templates. Several of
824 // the base class templates need to access other members of class
825 // template _Hashtable, so we use a variant of the "Curiously
826 // Recurring Template Pattern" (CRTP) technique.
827
828 /**
829 * Primary class template _Map_base.
830 *
831 * If the hashtable has a value type of the form pair<const T1, T2> and
832 * a key extraction policy (_ExtractKey) that returns the first part
833 * of the pair, the hashtable gets a mapped_type typedef. If it
834 * satisfies those criteria and also has unique keys, then it also
835 * gets an operator[].
836 */
837 template<typename _Key, typename _Value, typename _Alloc,
838 typename _ExtractKey, typename _Equal,
839 typename _Hash, typename _RangeHash, typename _Unused,
840 typename _RehashPolicy, typename _Traits,
841 bool _Unique_keys = _Traits::__unique_keys::value>
842 struct _Map_base { };
843
844 /// Partial specialization, __unique_keys set to false, std::pair value type.
845 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
846 typename _Hash, typename _RangeHash, typename _Unused,
847 typename _RehashPolicy, typename _Traits>
848 struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
849 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
850 {
851 using mapped_type = _Val;
852 };
853
854 /// Partial specialization, __unique_keys set to true.
855 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
856 typename _Hash, typename _RangeHash, typename _Unused,
857 typename _RehashPolicy, typename _Traits>
858 struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
859 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
860 {
861 private:
862 using __hashtable_base = _Hashtable_base<_Key, pair<const _Key, _Val>,
863 _Select1st, _Equal, _Hash,
864 _RangeHash, _Unused,
865 _Traits>;
866
867 using __hashtable = _Hashtable<_Key, pair<const _Key, _Val>, _Alloc,
868 _Select1st, _Equal, _Hash, _RangeHash,
869 _Unused, _RehashPolicy, _Traits>;
870
871 using __hash_code = typename __hashtable_base::__hash_code;
872
873 public:
874 using key_type = typename __hashtable_base::key_type;
875 using mapped_type = _Val;
876
877 mapped_type&
878 operator[](const key_type& __k);
879
880 mapped_type&
881 operator[](key_type&& __k);
882
883 // _GLIBCXX_RESOLVE_LIB_DEFECTS
884 // DR 761. unordered_map needs an at() member function.
885 mapped_type&
886 at(const key_type& __k)
887 {
888 auto __ite = static_cast<__hashtable*>(this)->find(__k);
889 if (!__ite._M_cur)
890 __throw_out_of_range(__N("unordered_map::at"));
891 return __ite->second;
892 }
893
894 const mapped_type&
895 at(const key_type& __k) const
896 {
897 auto __ite = static_cast<const __hashtable*>(this)->find(__k);
898 if (!__ite._M_cur)
899 __throw_out_of_range(__N("unordered_map::at"));
900 return __ite->second;
901 }
902 };
903
904 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
905 typename _Hash, typename _RangeHash, typename _Unused,
906 typename _RehashPolicy, typename _Traits>
907 auto
908 _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
909 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
910 operator[](const key_type& __k)
911 -> mapped_type&
912 {
913 __hashtable* __h = static_cast<__hashtable*>(this);
914 __hash_code __code = __h->_M_hash_code(__k);
915 std::size_t __bkt = __h->_M_bucket_index(__code);
916 if (auto __node = __h->_M_find_node(__bkt, __k, __code))
917 return __node->_M_v().second;
918
919 typename __hashtable::_Scoped_node __node {
920 __h,
924 };
925 auto __pos
926 = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
927 __node._M_node = nullptr;
928 return __pos->second;
929 }
930
931 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
932 typename _Hash, typename _RangeHash, typename _Unused,
933 typename _RehashPolicy, typename _Traits>
934 auto
935 _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
936 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
937 operator[](key_type&& __k)
938 -> mapped_type&
939 {
940 __hashtable* __h = static_cast<__hashtable*>(this);
941 __hash_code __code = __h->_M_hash_code(__k);
942 std::size_t __bkt = __h->_M_bucket_index(__code);
943 if (auto __node = __h->_M_find_node(__bkt, __k, __code))
944 return __node->_M_v().second;
945
946 typename __hashtable::_Scoped_node __node {
947 __h,
951 };
952 auto __pos
953 = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
954 __node._M_node = nullptr;
955 return __pos->second;
956 }
957
958 // Partial specialization for unordered_map<const T, U>, see PR 104174.
959 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
960 typename _Hash, typename _RangeHash, typename _Unused,
961 typename _RehashPolicy, typename _Traits, bool __uniq>
962 struct _Map_base<const _Key, pair<const _Key, _Val>,
963 _Alloc, _Select1st, _Equal, _Hash,
964 _RangeHash, _Unused, _RehashPolicy, _Traits, __uniq>
965 : _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal, _Hash,
966 _RangeHash, _Unused, _RehashPolicy, _Traits, __uniq>
967 { };
968
969 /**
970 * Primary class template _Insert_base.
971 *
972 * Defines @c insert member functions appropriate to all _Hashtables.
973 */
974 template<typename _Key, typename _Value, typename _Alloc,
975 typename _ExtractKey, typename _Equal,
976 typename _Hash, typename _RangeHash, typename _Unused,
977 typename _RehashPolicy, typename _Traits>
978 struct _Insert_base
979 {
980 protected:
981 using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
982 _Equal, _Hash, _RangeHash,
983 _Unused, _Traits>;
984
985 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
986 _Hash, _RangeHash,
987 _Unused, _RehashPolicy, _Traits>;
988
989 using __hash_cached = typename _Traits::__hash_cached;
990 using __constant_iterators = typename _Traits::__constant_iterators;
991
992 using __hashtable_alloc = _Hashtable_alloc<
993 __alloc_rebind<_Alloc, _Hash_node<_Value,
994 __hash_cached::value>>>;
995
996 using value_type = typename __hashtable_base::value_type;
997 using size_type = typename __hashtable_base::size_type;
998
999 using __unique_keys = typename _Traits::__unique_keys;
1000 using __node_alloc_type = typename __hashtable_alloc::__node_alloc_type;
1001 using __node_gen_type = _AllocNode<__node_alloc_type>;
1002
1003 __hashtable&
1004 _M_conjure_hashtable()
1005 { return *(static_cast<__hashtable*>(this)); }
1006
1007 template<typename _InputIterator, typename _NodeGetter>
1008 void
1009 _M_insert_range(_InputIterator __first, _InputIterator __last,
1010 const _NodeGetter&, true_type __uks);
1011
1012 template<typename _InputIterator, typename _NodeGetter>
1013 void
1014 _M_insert_range(_InputIterator __first, _InputIterator __last,
1015 const _NodeGetter&, false_type __uks);
1016
1017 public:
1018 using iterator = _Node_iterator<_Value, __constant_iterators::value,
1019 __hash_cached::value>;
1020
1021 using const_iterator = _Node_const_iterator<_Value,
1022 __constant_iterators::value,
1023 __hash_cached::value>;
1024
1025 using __ireturn_type = __conditional_t<__unique_keys::value,
1027 iterator>;
1028
1029 __ireturn_type
1030 insert(const value_type& __v)
1031 {
1032 __hashtable& __h = _M_conjure_hashtable();
1033 __node_gen_type __node_gen(__h);
1034 return __h._M_insert(__v, __node_gen, __unique_keys{});
1035 }
1036
1037 iterator
1038 insert(const_iterator __hint, const value_type& __v)
1039 {
1040 __hashtable& __h = _M_conjure_hashtable();
1041 __node_gen_type __node_gen(__h);
1042 return __h._M_insert(__hint, __v, __node_gen, __unique_keys{});
1043 }
1044
1045#ifdef __glibcxx_unordered_map_try_emplace // C++ >= 17 && HOSTED
1046 template<typename _KType, typename... _Args>
1048 try_emplace(const_iterator, _KType&& __k, _Args&&... __args)
1049 {
1050 __hashtable& __h = _M_conjure_hashtable();
1051 auto __code = __h._M_hash_code(__k);
1052 std::size_t __bkt = __h._M_bucket_index(__code);
1053 if (auto __node = __h._M_find_node(__bkt, __k, __code))
1054 return { iterator(__node), false };
1055
1056 typename __hashtable::_Scoped_node __node {
1057 &__h,
1061 };
1062 auto __it
1063 = __h._M_insert_unique_node(__bkt, __code, __node._M_node);
1064 __node._M_node = nullptr;
1065 return { __it, true };
1066 }
1067#endif
1068
1069 void
1070 insert(initializer_list<value_type> __l)
1071 { this->insert(__l.begin(), __l.end()); }
1072
1073 template<typename _InputIterator>
1074 void
1075 insert(_InputIterator __first, _InputIterator __last)
1076 {
1077 __hashtable& __h = _M_conjure_hashtable();
1078 __node_gen_type __node_gen(__h);
1079 return _M_insert_range(__first, __last, __node_gen, __unique_keys{});
1080 }
1081 };
1082
1083 template<typename _Key, typename _Value, typename _Alloc,
1084 typename _ExtractKey, typename _Equal,
1085 typename _Hash, typename _RangeHash, typename _Unused,
1086 typename _RehashPolicy, typename _Traits>
1087 template<typename _InputIterator, typename _NodeGetter>
1088 void
1089 _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1090 _Hash, _RangeHash, _Unused,
1091 _RehashPolicy, _Traits>::
1092 _M_insert_range(_InputIterator __first, _InputIterator __last,
1093 const _NodeGetter& __node_gen, true_type __uks)
1094 {
1095 __hashtable& __h = _M_conjure_hashtable();
1096 for (; __first != __last; ++__first)
1097 __h._M_insert(*__first, __node_gen, __uks);
1098 }
1099
1100 template<typename _Key, typename _Value, typename _Alloc,
1101 typename _ExtractKey, typename _Equal,
1102 typename _Hash, typename _RangeHash, typename _Unused,
1103 typename _RehashPolicy, typename _Traits>
1104 template<typename _InputIterator, typename _NodeGetter>
1105 void
1106 _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1107 _Hash, _RangeHash, _Unused,
1108 _RehashPolicy, _Traits>::
1109 _M_insert_range(_InputIterator __first, _InputIterator __last,
1110 const _NodeGetter& __node_gen, false_type __uks)
1111 {
1112 using __rehash_guard_t = typename __hashtable::__rehash_guard_t;
1113 using __pair_type = std::pair<bool, std::size_t>;
1114
1115 size_type __n_elt = __detail::__distance_fw(__first, __last);
1116 if (__n_elt == 0)
1117 return;
1118
1119 __hashtable& __h = _M_conjure_hashtable();
1120 __rehash_guard_t __rehash_guard(__h._M_rehash_policy);
1121 __pair_type __do_rehash
1122 = __h._M_rehash_policy._M_need_rehash(__h._M_bucket_count,
1123 __h._M_element_count,
1124 __n_elt);
1125
1126 if (__do_rehash.first)
1127 __h._M_rehash(__do_rehash.second, __uks);
1128
1129 __rehash_guard._M_guarded_obj = nullptr;
1130 for (; __first != __last; ++__first)
1131 __h._M_insert(*__first, __node_gen, __uks);
1132 }
1133
1134 /**
1135 * Primary class template _Insert.
1136 *
1137 * Defines @c insert member functions that depend on _Hashtable policies,
1138 * via partial specializations.
1139 */
1140 template<typename _Key, typename _Value, typename _Alloc,
1141 typename _ExtractKey, typename _Equal,
1142 typename _Hash, typename _RangeHash, typename _Unused,
1143 typename _RehashPolicy, typename _Traits,
1144 bool _Constant_iterators = _Traits::__constant_iterators::value>
1145 struct _Insert;
1146
1147 /// Specialization.
1148 template<typename _Key, typename _Value, typename _Alloc,
1149 typename _ExtractKey, typename _Equal,
1150 typename _Hash, typename _RangeHash, typename _Unused,
1151 typename _RehashPolicy, typename _Traits>
1152 struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1153 _Hash, _RangeHash, _Unused,
1154 _RehashPolicy, _Traits, true>
1155 : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1156 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>
1157 {
1158 using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
1159 _Equal, _Hash, _RangeHash, _Unused,
1160 _RehashPolicy, _Traits>;
1161
1162 using value_type = typename __base_type::value_type;
1163 using iterator = typename __base_type::iterator;
1164 using const_iterator = typename __base_type::const_iterator;
1165 using __ireturn_type = typename __base_type::__ireturn_type;
1166
1167 using __unique_keys = typename __base_type::__unique_keys;
1168 using __hashtable = typename __base_type::__hashtable;
1169 using __node_gen_type = typename __base_type::__node_gen_type;
1170
1171 using __base_type::insert;
1172
1173 __ireturn_type
1174 insert(value_type&& __v)
1175 {
1176 __hashtable& __h = this->_M_conjure_hashtable();
1177 __node_gen_type __node_gen(__h);
1178 return __h._M_insert(std::move(__v), __node_gen, __unique_keys{});
1179 }
1180
1181 iterator
1182 insert(const_iterator __hint, value_type&& __v)
1183 {
1184 __hashtable& __h = this->_M_conjure_hashtable();
1185 __node_gen_type __node_gen(__h);
1186 return __h._M_insert(__hint, std::move(__v), __node_gen,
1187 __unique_keys{});
1188 }
1189 };
1190
1191 /// Specialization.
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 _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1197 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
1198 : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1199 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>
1200 {
1201 using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
1202 _Equal, _Hash, _RangeHash, _Unused,
1203 _RehashPolicy, _Traits>;
1204 using value_type = typename __base_type::value_type;
1205 using iterator = typename __base_type::iterator;
1206 using const_iterator = typename __base_type::const_iterator;
1207
1208 using __unique_keys = typename __base_type::__unique_keys;
1209 using __hashtable = typename __base_type::__hashtable;
1210 using __ireturn_type = typename __base_type::__ireturn_type;
1211
1212 using __base_type::insert;
1213
1214 template<typename _Pair>
1216
1217 template<typename _Pair>
1219
1220 template<typename _Pair>
1221 using _IFconsp = typename _IFcons<_Pair>::type;
1222
1223 template<typename _Pair, typename = _IFconsp<_Pair>>
1224 __ireturn_type
1225 insert(_Pair&& __v)
1226 {
1227 __hashtable& __h = this->_M_conjure_hashtable();
1228 return __h._M_emplace(__unique_keys{}, std::forward<_Pair>(__v));
1229 }
1230
1231 template<typename _Pair, typename = _IFconsp<_Pair>>
1232 iterator
1233 insert(const_iterator __hint, _Pair&& __v)
1234 {
1235 __hashtable& __h = this->_M_conjure_hashtable();
1236 return __h._M_emplace(__hint, __unique_keys{},
1237 std::forward<_Pair>(__v));
1238 }
1239 };
1240
1241 template<typename _Policy>
1242 using __has_load_factor = typename _Policy::__has_load_factor;
1243
1244 /**
1245 * Primary class template _Rehash_base.
1246 *
1247 * Give hashtable the max_load_factor functions and reserve iff the
1248 * rehash policy supports it.
1249 */
1250 template<typename _Key, typename _Value, typename _Alloc,
1251 typename _ExtractKey, typename _Equal,
1252 typename _Hash, typename _RangeHash, typename _Unused,
1253 typename _RehashPolicy, typename _Traits,
1254 typename =
1255 __detected_or_t<false_type, __has_load_factor, _RehashPolicy>>
1256 struct _Rehash_base;
1257
1258 /// Specialization when rehash policy doesn't provide load factor management.
1259 template<typename _Key, typename _Value, typename _Alloc,
1260 typename _ExtractKey, typename _Equal,
1261 typename _Hash, typename _RangeHash, typename _Unused,
1262 typename _RehashPolicy, typename _Traits>
1263 struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1264 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
1265 false_type /* Has load factor */>
1266 {
1267 };
1268
1269 /// Specialization when rehash policy provide load factor management.
1270 template<typename _Key, typename _Value, typename _Alloc,
1271 typename _ExtractKey, typename _Equal,
1272 typename _Hash, typename _RangeHash, typename _Unused,
1273 typename _RehashPolicy, typename _Traits>
1274 struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1275 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
1276 true_type /* Has load factor */>
1277 {
1278 private:
1279 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
1280 _Equal, _Hash, _RangeHash, _Unused,
1281 _RehashPolicy, _Traits>;
1282
1283 public:
1284 float
1285 max_load_factor() const noexcept
1286 {
1287 const __hashtable* __this = static_cast<const __hashtable*>(this);
1288 return __this->__rehash_policy().max_load_factor();
1289 }
1290
1291 void
1292 max_load_factor(float __z)
1293 {
1294 __hashtable* __this = static_cast<__hashtable*>(this);
1295 __this->__rehash_policy(_RehashPolicy(__z));
1296 }
1297
1298 void
1299 reserve(std::size_t __n)
1300 {
1301 __hashtable* __this = static_cast<__hashtable*>(this);
1302 __this->rehash(__this->__rehash_policy()._M_bkt_for_elements(__n));
1303 }
1304 };
1305
1306 /**
1307 * Primary class template _Hashtable_ebo_helper.
1308 *
1309 * Helper class using EBO when it is not forbidden (the type is not
1310 * final) and when it is worth it (the type is empty.)
1311 */
1312 template<int _Nm, typename _Tp,
1313 bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
1314 struct _Hashtable_ebo_helper;
1315
1316 /// Specialization using EBO.
1317 template<int _Nm, typename _Tp>
1318 struct _Hashtable_ebo_helper<_Nm, _Tp, true>
1319 : private _Tp
1320 {
1321 _Hashtable_ebo_helper() noexcept(noexcept(_Tp())) : _Tp() { }
1322
1323 template<typename _OtherTp>
1324 _Hashtable_ebo_helper(_OtherTp&& __tp)
1325 : _Tp(std::forward<_OtherTp>(__tp))
1326 { }
1327
1328 const _Tp& _M_cget() const { return static_cast<const _Tp&>(*this); }
1329 _Tp& _M_get() { return static_cast<_Tp&>(*this); }
1330 };
1331
1332 /// Specialization not using EBO.
1333 template<int _Nm, typename _Tp>
1334 struct _Hashtable_ebo_helper<_Nm, _Tp, false>
1335 {
1336 _Hashtable_ebo_helper() = default;
1337
1338 template<typename _OtherTp>
1339 _Hashtable_ebo_helper(_OtherTp&& __tp)
1340 : _M_tp(std::forward<_OtherTp>(__tp))
1341 { }
1342
1343 const _Tp& _M_cget() const { return _M_tp; }
1344 _Tp& _M_get() { return _M_tp; }
1345
1346 private:
1347 _Tp _M_tp{};
1348 };
1349
1350 /**
1351 * Primary class template _Local_iterator_base.
1352 *
1353 * Base class for local iterators, used to iterate within a bucket
1354 * but not between buckets.
1355 */
1356 template<typename _Key, typename _Value, typename _ExtractKey,
1357 typename _Hash, typename _RangeHash, typename _Unused,
1358 bool __cache_hash_code>
1359 struct _Local_iterator_base;
1360
1361 /**
1362 * Primary class template _Hash_code_base.
1363 *
1364 * Encapsulates two policy issues that aren't quite orthogonal.
1365 * (1) the difference between using a ranged hash function and using
1366 * the combination of a hash function and a range-hashing function.
1367 * In the former case we don't have such things as hash codes, so
1368 * we have a dummy type as placeholder.
1369 * (2) Whether or not we cache hash codes. Caching hash codes is
1370 * meaningless if we have a ranged hash function.
1371 *
1372 * We also put the key extraction objects here, for convenience.
1373 * Each specialization derives from one or more of the template
1374 * parameters to benefit from Ebo. This is important as this type
1375 * is inherited in some cases by the _Local_iterator_base type used
1376 * to implement local_iterator and const_local_iterator. As with
1377 * any iterator type we prefer to make it as small as possible.
1378 */
1379 template<typename _Key, typename _Value, typename _ExtractKey,
1380 typename _Hash, typename _RangeHash, typename _Unused,
1381 bool __cache_hash_code>
1382 struct _Hash_code_base
1383 : private _Hashtable_ebo_helper<1, _Hash>
1384 {
1385 private:
1386 using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>;
1387
1388 // Gives the local iterator implementation access to _M_bucket_index().
1389 friend struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1390 _Hash, _RangeHash, _Unused, false>;
1391
1392 public:
1393 typedef _Hash hasher;
1394
1395 hasher
1396 hash_function() const
1397 { return _M_hash(); }
1398
1399 protected:
1400 typedef std::size_t __hash_code;
1401
1402 // We need the default constructor for the local iterators and _Hashtable
1403 // default constructor.
1404 _Hash_code_base() = default;
1405
1406 _Hash_code_base(const _Hash& __hash) : __ebo_hash(__hash) { }
1407
1408 __hash_code
1409 _M_hash_code(const _Key& __k) const
1410 {
1411 static_assert(__is_invocable<const _Hash&, const _Key&>{},
1412 "hash function must be invocable with an argument of key type");
1413 return _M_hash()(__k);
1414 }
1415
1416 template<typename _Kt>
1417 __hash_code
1418 _M_hash_code_tr(const _Kt& __k) const
1419 {
1420 static_assert(__is_invocable<const _Hash&, const _Kt&>{},
1421 "hash function must be invocable with an argument of key type");
1422 return _M_hash()(__k);
1423 }
1424
1425 __hash_code
1426 _M_hash_code(const _Hash_node_value<_Value, false>& __n) const
1427 { return _M_hash_code(_ExtractKey{}(__n._M_v())); }
1428
1429 __hash_code
1430 _M_hash_code(const _Hash_node_value<_Value, true>& __n) const
1431 { return __n._M_hash_code; }
1432
1433 std::size_t
1434 _M_bucket_index(__hash_code __c, std::size_t __bkt_count) const
1435 { return _RangeHash{}(__c, __bkt_count); }
1436
1437 std::size_t
1438 _M_bucket_index(const _Hash_node_value<_Value, false>& __n,
1439 std::size_t __bkt_count) const
1440 noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>()))
1441 && noexcept(declval<const _RangeHash&>()((__hash_code)0,
1442 (std::size_t)0)) )
1443 {
1444 return _RangeHash{}(_M_hash_code(_ExtractKey{}(__n._M_v())),
1445 __bkt_count);
1446 }
1447
1448 std::size_t
1449 _M_bucket_index(const _Hash_node_value<_Value, true>& __n,
1450 std::size_t __bkt_count) const
1451 noexcept( noexcept(declval<const _RangeHash&>()((__hash_code)0,
1452 (std::size_t)0)) )
1453 { return _RangeHash{}(__n._M_hash_code, __bkt_count); }
1454
1455 void
1456 _M_store_code(_Hash_node_code_cache<false>&, __hash_code) const
1457 { }
1458
1459 void
1460 _M_copy_code(_Hash_node_code_cache<false>&,
1461 const _Hash_node_code_cache<false>&) const
1462 { }
1463
1464 void
1465 _M_store_code(_Hash_node_code_cache<true>& __n, __hash_code __c) const
1466 { __n._M_hash_code = __c; }
1467
1468 void
1469 _M_copy_code(_Hash_node_code_cache<true>& __to,
1470 const _Hash_node_code_cache<true>& __from) const
1471 { __to._M_hash_code = __from._M_hash_code; }
1472
1473 void
1474 _M_swap(_Hash_code_base& __x)
1475 {
1476 using std::swap;
1477 swap(__ebo_hash::_M_get(), __x.__ebo_hash::_M_get());
1478 }
1479
1480 const _Hash&
1481 _M_hash() const { return __ebo_hash::_M_cget(); }
1482 };
1483
1484 /// Partial specialization used when nodes contain a cached hash code.
1485 template<typename _Key, typename _Value, typename _ExtractKey,
1486 typename _Hash, typename _RangeHash, typename _Unused>
1487 struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1488 _Hash, _RangeHash, _Unused, true>
1489 : public _Node_iterator_base<_Value, true>
1490 {
1491 protected:
1492 using __base_node_iter = _Node_iterator_base<_Value, true>;
1493 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1494 _Hash, _RangeHash, _Unused, true>;
1495
1496 _Local_iterator_base() = default;
1497 _Local_iterator_base(const __hash_code_base&,
1498 _Hash_node<_Value, true>* __p,
1499 std::size_t __bkt, std::size_t __bkt_count)
1500 : __base_node_iter(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1501 { }
1502
1503 void
1504 _M_incr()
1505 {
1506 __base_node_iter::_M_incr();
1507 if (this->_M_cur)
1508 {
1509 std::size_t __bkt
1510 = _RangeHash{}(this->_M_cur->_M_hash_code, _M_bucket_count);
1511 if (__bkt != _M_bucket)
1512 this->_M_cur = nullptr;
1513 }
1514 }
1515
1516 std::size_t _M_bucket;
1517 std::size_t _M_bucket_count;
1518
1519 public:
1520 std::size_t
1521 _M_get_bucket() const { return _M_bucket; } // for debug mode
1522 };
1523
1524 // Uninitialized storage for a _Hash_code_base.
1525 // This type is DefaultConstructible and Assignable even if the
1526 // _Hash_code_base type isn't, so that _Local_iterator_base<..., false>
1527 // can be DefaultConstructible and Assignable.
1528 template<typename _Tp, bool _IsEmpty = std::is_empty<_Tp>::value>
1529 struct _Hash_code_storage
1530 {
1531 __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
1532
1533 _Tp*
1534 _M_h() { return _M_storage._M_ptr(); }
1535
1536 const _Tp*
1537 _M_h() const { return _M_storage._M_ptr(); }
1538 };
1539
1540 // Empty partial specialization for empty _Hash_code_base types.
1541 template<typename _Tp>
1542 struct _Hash_code_storage<_Tp, true>
1543 {
1544 static_assert( std::is_empty<_Tp>::value, "Type must be empty" );
1545
1546 // As _Tp is an empty type there will be no bytes written/read through
1547 // the cast pointer, so no strict-aliasing violation.
1548 _Tp*
1549 _M_h() { return reinterpret_cast<_Tp*>(this); }
1550
1551 const _Tp*
1552 _M_h() const { return reinterpret_cast<const _Tp*>(this); }
1553 };
1554
1555 template<typename _Key, typename _Value, typename _ExtractKey,
1556 typename _Hash, typename _RangeHash, typename _Unused>
1557 using __hash_code_for_local_iter
1558 = _Hash_code_storage<_Hash_code_base<_Key, _Value, _ExtractKey,
1559 _Hash, _RangeHash, _Unused, false>>;
1560
1561 // Partial specialization used when hash codes are not cached
1562 template<typename _Key, typename _Value, typename _ExtractKey,
1563 typename _Hash, typename _RangeHash, typename _Unused>
1564 struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1565 _Hash, _RangeHash, _Unused, false>
1566 : __hash_code_for_local_iter<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1567 _Unused>
1568 , _Node_iterator_base<_Value, false>
1569 {
1570 protected:
1571 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1572 _Hash, _RangeHash, _Unused, false>;
1573 using __node_iter_base = _Node_iterator_base<_Value, false>;
1574
1575 _Local_iterator_base() : _M_bucket_count(-1) { }
1576
1577 _Local_iterator_base(const __hash_code_base& __base,
1578 _Hash_node<_Value, false>* __p,
1579 std::size_t __bkt, std::size_t __bkt_count)
1580 : __node_iter_base(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1581 { _M_init(__base); }
1582
1583 ~_Local_iterator_base()
1584 {
1585 if (_M_bucket_count != size_t(-1))
1586 _M_destroy();
1587 }
1588
1589 _Local_iterator_base(const _Local_iterator_base& __iter)
1590 : __node_iter_base(__iter._M_cur), _M_bucket(__iter._M_bucket)
1591 , _M_bucket_count(__iter._M_bucket_count)
1592 {
1593 if (_M_bucket_count != size_t(-1))
1594 _M_init(*__iter._M_h());
1595 }
1596
1597 _Local_iterator_base&
1598 operator=(const _Local_iterator_base& __iter)
1599 {
1600 if (_M_bucket_count != -1)
1601 _M_destroy();
1602 this->_M_cur = __iter._M_cur;
1603 _M_bucket = __iter._M_bucket;
1604 _M_bucket_count = __iter._M_bucket_count;
1605 if (_M_bucket_count != -1)
1606 _M_init(*__iter._M_h());
1607 return *this;
1608 }
1609
1610 void
1611 _M_incr()
1612 {
1613 __node_iter_base::_M_incr();
1614 if (this->_M_cur)
1615 {
1616 std::size_t __bkt = this->_M_h()->_M_bucket_index(*this->_M_cur,
1617 _M_bucket_count);
1618 if (__bkt != _M_bucket)
1619 this->_M_cur = nullptr;
1620 }
1621 }
1622
1623 std::size_t _M_bucket;
1624 std::size_t _M_bucket_count;
1625
1626 void
1627 _M_init(const __hash_code_base& __base)
1628 { ::new(this->_M_h()) __hash_code_base(__base); }
1629
1630 void
1631 _M_destroy() { this->_M_h()->~__hash_code_base(); }
1632
1633 public:
1634 std::size_t
1635 _M_get_bucket() const { return _M_bucket; } // for debug mode
1636 };
1637
1638 /// local iterators
1639 template<typename _Key, typename _Value, typename _ExtractKey,
1640 typename _Hash, typename _RangeHash, typename _Unused,
1641 bool __constant_iterators, bool __cache>
1642 struct _Local_iterator
1643 : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1644 _Hash, _RangeHash, _Unused, __cache>
1645 {
1646 private:
1647 using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1648 _Hash, _RangeHash, _Unused, __cache>;
1649 using __hash_code_base = typename __base_type::__hash_code_base;
1650
1651 public:
1652 using value_type = _Value;
1653 using pointer = __conditional_t<__constant_iterators,
1654 const value_type*, value_type*>;
1655 using reference = __conditional_t<__constant_iterators,
1656 const value_type&, value_type&>;
1657 using difference_type = ptrdiff_t;
1658 using iterator_category = forward_iterator_tag;
1659
1660 _Local_iterator() = default;
1661
1662 _Local_iterator(const __hash_code_base& __base,
1663 _Hash_node<_Value, __cache>* __n,
1664 std::size_t __bkt, std::size_t __bkt_count)
1665 : __base_type(__base, __n, __bkt, __bkt_count)
1666 { }
1667
1668 reference
1669 operator*() const
1670 { return this->_M_cur->_M_v(); }
1671
1672 pointer
1673 operator->() const
1674 { return this->_M_cur->_M_valptr(); }
1675
1676 _Local_iterator&
1677 operator++()
1678 {
1679 this->_M_incr();
1680 return *this;
1681 }
1682
1683 _Local_iterator
1684 operator++(int)
1685 {
1686 _Local_iterator __tmp(*this);
1687 this->_M_incr();
1688 return __tmp;
1689 }
1690 };
1691
1692 /// local const_iterators
1693 template<typename _Key, typename _Value, typename _ExtractKey,
1694 typename _Hash, typename _RangeHash, typename _Unused,
1695 bool __constant_iterators, bool __cache>
1696 struct _Local_const_iterator
1697 : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1698 _Hash, _RangeHash, _Unused, __cache>
1699 {
1700 private:
1701 using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1702 _Hash, _RangeHash, _Unused, __cache>;
1703 using __hash_code_base = typename __base_type::__hash_code_base;
1704
1705 public:
1706 typedef _Value value_type;
1707 typedef const value_type* pointer;
1708 typedef const value_type& reference;
1709 typedef std::ptrdiff_t difference_type;
1710 typedef std::forward_iterator_tag iterator_category;
1711
1712 _Local_const_iterator() = default;
1713
1714 _Local_const_iterator(const __hash_code_base& __base,
1715 _Hash_node<_Value, __cache>* __n,
1716 std::size_t __bkt, std::size_t __bkt_count)
1717 : __base_type(__base, __n, __bkt, __bkt_count)
1718 { }
1719
1720 _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
1721 _Hash, _RangeHash, _Unused,
1722 __constant_iterators,
1723 __cache>& __x)
1724 : __base_type(__x)
1725 { }
1726
1727 reference
1728 operator*() const
1729 { return this->_M_cur->_M_v(); }
1730
1731 pointer
1732 operator->() const
1733 { return this->_M_cur->_M_valptr(); }
1734
1735 _Local_const_iterator&
1736 operator++()
1737 {
1738 this->_M_incr();
1739 return *this;
1740 }
1741
1742 _Local_const_iterator
1743 operator++(int)
1744 {
1745 _Local_const_iterator __tmp(*this);
1746 this->_M_incr();
1747 return __tmp;
1748 }
1749 };
1750
1751 /**
1752 * Primary class template _Hashtable_base.
1753 *
1754 * Helper class adding management of _Equal functor to
1755 * _Hash_code_base type.
1756 *
1757 * Base class templates are:
1758 * - __detail::_Hash_code_base
1759 * - __detail::_Hashtable_ebo_helper
1760 */
1761 template<typename _Key, typename _Value, typename _ExtractKey,
1762 typename _Equal, typename _Hash, typename _RangeHash,
1763 typename _Unused, typename _Traits>
1764 struct _Hashtable_base
1765 : public _Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1766 _Unused, _Traits::__hash_cached::value>,
1767 private _Hashtable_ebo_helper<0, _Equal>
1768 {
1769 public:
1770 typedef _Key key_type;
1771 typedef _Value value_type;
1772 typedef _Equal key_equal;
1773 typedef std::size_t size_type;
1774 typedef std::ptrdiff_t difference_type;
1775
1776 using __traits_type = _Traits;
1777 using __hash_cached = typename __traits_type::__hash_cached;
1778
1779 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1780 _Hash, _RangeHash, _Unused,
1781 __hash_cached::value>;
1782
1783 using __hash_code = typename __hash_code_base::__hash_code;
1784
1785 private:
1786 using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>;
1787
1788 static bool
1789 _S_equals(__hash_code, const _Hash_node_code_cache<false>&)
1790 { return true; }
1791
1792 static bool
1793 _S_node_equals(const _Hash_node_code_cache<false>&,
1794 const _Hash_node_code_cache<false>&)
1795 { return true; }
1796
1797 static bool
1798 _S_equals(__hash_code __c, const _Hash_node_code_cache<true>& __n)
1799 { return __c == __n._M_hash_code; }
1800
1801 static bool
1802 _S_node_equals(const _Hash_node_code_cache<true>& __lhn,
1803 const _Hash_node_code_cache<true>& __rhn)
1804 { return __lhn._M_hash_code == __rhn._M_hash_code; }
1805
1806 protected:
1807 _Hashtable_base() = default;
1808
1809 _Hashtable_base(const _Hash& __hash, const _Equal& __eq)
1810 : __hash_code_base(__hash), _EqualEBO(__eq)
1811 { }
1812
1813 bool
1814 _M_key_equals(const _Key& __k,
1815 const _Hash_node_value<_Value,
1816 __hash_cached::value>& __n) const
1817 {
1818 static_assert(__is_invocable<const _Equal&, const _Key&, const _Key&>{},
1819 "key equality predicate must be invocable with two arguments of "
1820 "key type");
1821 return _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1822 }
1823
1824 template<typename _Kt>
1825 bool
1826 _M_key_equals_tr(const _Kt& __k,
1827 const _Hash_node_value<_Value,
1828 __hash_cached::value>& __n) const
1829 {
1830 static_assert(
1831 __is_invocable<const _Equal&, const _Kt&, const _Key&>{},
1832 "key equality predicate must be invocable with two arguments of "
1833 "key type");
1834 return _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1835 }
1836
1837 bool
1838 _M_equals(const _Key& __k, __hash_code __c,
1839 const _Hash_node_value<_Value, __hash_cached::value>& __n) const
1840 { return _S_equals(__c, __n) && _M_key_equals(__k, __n); }
1841
1842 template<typename _Kt>
1843 bool
1844 _M_equals_tr(const _Kt& __k, __hash_code __c,
1845 const _Hash_node_value<_Value,
1846 __hash_cached::value>& __n) const
1847 { return _S_equals(__c, __n) && _M_key_equals_tr(__k, __n); }
1848
1849 bool
1850 _M_node_equals(
1851 const _Hash_node_value<_Value, __hash_cached::value>& __lhn,
1852 const _Hash_node_value<_Value, __hash_cached::value>& __rhn) const
1853 {
1854 return _S_node_equals(__lhn, __rhn)
1855 && _M_key_equals(_ExtractKey{}(__lhn._M_v()), __rhn);
1856 }
1857
1858 void
1859 _M_swap(_Hashtable_base& __x)
1860 {
1861 __hash_code_base::_M_swap(__x);
1862 using std::swap;
1863 swap(_EqualEBO::_M_get(), __x._EqualEBO::_M_get());
1864 }
1865
1866 const _Equal&
1867 _M_eq() const { return _EqualEBO::_M_cget(); }
1868 };
1869
1870 /**
1871 * Primary class template _Equality.
1872 *
1873 * This is for implementing equality comparison for unordered
1874 * containers, per N3068, by John Lakos and Pablo Halpern.
1875 * Algorithmically, we follow closely the reference implementations
1876 * therein.
1877 */
1878 template<typename _Key, typename _Value, typename _Alloc,
1879 typename _ExtractKey, typename _Equal,
1880 typename _Hash, typename _RangeHash, typename _Unused,
1881 typename _RehashPolicy, typename _Traits,
1882 bool _Unique_keys = _Traits::__unique_keys::value>
1883 struct _Equality;
1884
1885 /// unordered_map and unordered_set specializations.
1886 template<typename _Key, typename _Value, typename _Alloc,
1887 typename _ExtractKey, typename _Equal,
1888 typename _Hash, typename _RangeHash, typename _Unused,
1889 typename _RehashPolicy, typename _Traits>
1890 struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1891 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
1892 {
1893 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1894 _Hash, _RangeHash, _Unused,
1895 _RehashPolicy, _Traits>;
1896
1897 bool
1898 _M_equal(const __hashtable&) const;
1899 };
1900
1901 template<typename _Key, typename _Value, typename _Alloc,
1902 typename _ExtractKey, typename _Equal,
1903 typename _Hash, typename _RangeHash, typename _Unused,
1904 typename _RehashPolicy, typename _Traits>
1905 bool
1906 _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1907 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
1908 _M_equal(const __hashtable& __other) const
1909 {
1910 using __node_ptr = typename __hashtable::__node_ptr;
1911 const __hashtable* __this = static_cast<const __hashtable*>(this);
1912 if (__this->size() != __other.size())
1913 return false;
1914
1915 for (auto __x_n = __this->_M_begin(); __x_n; __x_n = __x_n->_M_next())
1916 {
1917 std::size_t __ybkt = __other._M_bucket_index(*__x_n);
1918 auto __prev_n = __other._M_buckets[__ybkt];
1919 if (!__prev_n)
1920 return false;
1921
1922 for (__node_ptr __n = static_cast<__node_ptr>(__prev_n->_M_nxt);;
1923 __n = __n->_M_next())
1924 {
1925 if (__n->_M_v() == __x_n->_M_v())
1926 break;
1927
1928 if (!__n->_M_nxt
1929 || __other._M_bucket_index(*__n->_M_next()) != __ybkt)
1930 return false;
1931 }
1932 }
1933
1934 return true;
1935 }
1936
1937 /// unordered_multiset and unordered_multimap specializations.
1938 template<typename _Key, typename _Value, typename _Alloc,
1939 typename _ExtractKey, typename _Equal,
1940 typename _Hash, typename _RangeHash, typename _Unused,
1941 typename _RehashPolicy, typename _Traits>
1942 struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1943 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
1944 {
1945 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1946 _Hash, _RangeHash, _Unused,
1947 _RehashPolicy, _Traits>;
1948
1949 bool
1950 _M_equal(const __hashtable&) const;
1951 };
1952
1953 template<typename _Key, typename _Value, typename _Alloc,
1954 typename _ExtractKey, typename _Equal,
1955 typename _Hash, typename _RangeHash, typename _Unused,
1956 typename _RehashPolicy, typename _Traits>
1957 bool
1958 _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1959 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>::
1960 _M_equal(const __hashtable& __other) const
1961 {
1962 using __node_ptr = typename __hashtable::__node_ptr;
1963 using const_iterator = typename __hashtable::const_iterator;
1964 const __hashtable* __this = static_cast<const __hashtable*>(this);
1965 if (__this->size() != __other.size())
1966 return false;
1967
1968 for (auto __x_n = __this->_M_begin(); __x_n;)
1969 {
1970 std::size_t __x_count = 1;
1971 auto __x_n_end = __x_n->_M_next();
1972 for (; __x_n_end
1973 && __this->key_eq()(_ExtractKey{}(__x_n->_M_v()),
1974 _ExtractKey{}(__x_n_end->_M_v()));
1975 __x_n_end = __x_n_end->_M_next())
1976 ++__x_count;
1977
1978 std::size_t __ybkt = __other._M_bucket_index(*__x_n);
1979 auto __y_prev_n = __other._M_buckets[__ybkt];
1980 if (!__y_prev_n)
1981 return false;
1982
1983 __node_ptr __y_n = static_cast<__node_ptr>(__y_prev_n->_M_nxt);
1984 for (;;)
1985 {
1986 if (__this->key_eq()(_ExtractKey{}(__y_n->_M_v()),
1987 _ExtractKey{}(__x_n->_M_v())))
1988 break;
1989
1990 auto __y_ref_n = __y_n;
1991 for (__y_n = __y_n->_M_next(); __y_n; __y_n = __y_n->_M_next())
1992 if (!__other._M_node_equals(*__y_ref_n, *__y_n))
1993 break;
1994
1995 if (!__y_n || __other._M_bucket_index(*__y_n) != __ybkt)
1996 return false;
1997 }
1998
1999 auto __y_n_end = __y_n;
2000 for (; __y_n_end; __y_n_end = __y_n_end->_M_next())
2001 if (--__x_count == 0)
2002 break;
2003
2004 if (__x_count != 0)
2005 return false;
2006
2007 const_iterator __itx(__x_n), __itx_end(__x_n_end);
2008 const_iterator __ity(__y_n);
2009 if (!std::is_permutation(__itx, __itx_end, __ity))
2010 return false;
2011
2012 __x_n = __x_n_end;
2013 }
2014 return true;
2015 }
2016
2017 /**
2018 * This type deals with all allocation and keeps an allocator instance
2019 * through inheritance to benefit from EBO when possible.
2020 */
2021 template<typename _NodeAlloc>
2022 struct _Hashtable_alloc : private _Hashtable_ebo_helper<0, _NodeAlloc>
2023 {
2024 private:
2025 using __ebo_node_alloc = _Hashtable_ebo_helper<0, _NodeAlloc>;
2026
2027 template<typename>
2028 struct __get_value_type;
2029 template<typename _Val, bool _Cache_hash_code>
2030 struct __get_value_type<_Hash_node<_Val, _Cache_hash_code>>
2031 { using type = _Val; };
2032
2033 public:
2034 using __node_type = typename _NodeAlloc::value_type;
2035 using __node_alloc_type = _NodeAlloc;
2036 // Use __gnu_cxx to benefit from _S_always_equal and al.
2037 using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
2038
2039 using __value_alloc_traits = typename __node_alloc_traits::template
2040 rebind_traits<typename __get_value_type<__node_type>::type>;
2041
2042 using __node_ptr = __node_type*;
2043 using __node_base = _Hash_node_base;
2044 using __node_base_ptr = __node_base*;
2045 using __buckets_alloc_type =
2046 __alloc_rebind<__node_alloc_type, __node_base_ptr>;
2047 using __buckets_alloc_traits = std::allocator_traits<__buckets_alloc_type>;
2048 using __buckets_ptr = __node_base_ptr*;
2049
2050 _Hashtable_alloc() = default;
2051 _Hashtable_alloc(const _Hashtable_alloc&) = default;
2052 _Hashtable_alloc(_Hashtable_alloc&&) = default;
2053
2054 template<typename _Alloc>
2055 _Hashtable_alloc(_Alloc&& __a)
2056 : __ebo_node_alloc(std::forward<_Alloc>(__a))
2057 { }
2058
2059 __node_alloc_type&
2060 _M_node_allocator()
2061 { return __ebo_node_alloc::_M_get(); }
2062
2063 const __node_alloc_type&
2064 _M_node_allocator() const
2065 { return __ebo_node_alloc::_M_cget(); }
2066
2067 // Allocate a node and construct an element within it.
2068 template<typename... _Args>
2069 __node_ptr
2070 _M_allocate_node(_Args&&... __args);
2071
2072 // Destroy the element within a node and deallocate the node.
2073 void
2074 _M_deallocate_node(__node_ptr __n);
2075
2076 // Deallocate a node.
2077 void
2078 _M_deallocate_node_ptr(__node_ptr __n);
2079
2080 // Deallocate the linked list of nodes pointed to by __n.
2081 // The elements within the nodes are destroyed.
2082 void
2083 _M_deallocate_nodes(__node_ptr __n);
2084
2085 __buckets_ptr
2086 _M_allocate_buckets(std::size_t __bkt_count);
2087
2088 void
2089 _M_deallocate_buckets(__buckets_ptr, std::size_t __bkt_count);
2090 };
2091
2092 // Definitions of class template _Hashtable_alloc's out-of-line member
2093 // functions.
2094 template<typename _NodeAlloc>
2095 template<typename... _Args>
2096 auto
2097 _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
2098 -> __node_ptr
2099 {
2100 auto& __alloc = _M_node_allocator();
2101 auto __nptr = __node_alloc_traits::allocate(__alloc, 1);
2102 __node_ptr __n = std::__to_address(__nptr);
2103 __try
2104 {
2105 ::new ((void*)__n) __node_type;
2106 __node_alloc_traits::construct(__alloc, __n->_M_valptr(),
2107 std::forward<_Args>(__args)...);
2108 return __n;
2109 }
2110 __catch(...)
2111 {
2112 __n->~__node_type();
2113 __node_alloc_traits::deallocate(__alloc, __nptr, 1);
2114 __throw_exception_again;
2115 }
2116 }
2117
2118 template<typename _NodeAlloc>
2119 void
2120 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_ptr __n)
2121 {
2122 __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
2123 _M_deallocate_node_ptr(__n);
2124 }
2125
2126 template<typename _NodeAlloc>
2127 void
2128 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node_ptr(__node_ptr __n)
2129 {
2130 typedef typename __node_alloc_traits::pointer _Ptr;
2131 auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
2132 __n->~__node_type();
2133 __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
2134 }
2135
2136 template<typename _NodeAlloc>
2137 void
2138 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_ptr __n)
2139 {
2140 while (__n)
2141 {
2142 __node_ptr __tmp = __n;
2143 __n = __n->_M_next();
2144 _M_deallocate_node(__tmp);
2145 }
2146 }
2147
2148 template<typename _NodeAlloc>
2149 auto
2150 _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(std::size_t __bkt_count)
2151 -> __buckets_ptr
2152 {
2153 __buckets_alloc_type __alloc(_M_node_allocator());
2154
2155 auto __ptr = __buckets_alloc_traits::allocate(__alloc, __bkt_count);
2156 __buckets_ptr __p = std::__to_address(__ptr);
2157 __builtin_memset(__p, 0, __bkt_count * sizeof(__node_base_ptr));
2158 return __p;
2159 }
2160
2161 template<typename _NodeAlloc>
2162 void
2163 _Hashtable_alloc<_NodeAlloc>::
2164 _M_deallocate_buckets(__buckets_ptr __bkts,
2165 std::size_t __bkt_count)
2166 {
2167 typedef typename __buckets_alloc_traits::pointer _Ptr;
2168 auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
2169 __buckets_alloc_type __alloc(_M_node_allocator());
2170 __buckets_alloc_traits::deallocate(__alloc, __ptr, __bkt_count);
2171 }
2172
2173 ///@} hashtable-detail
2174} // namespace __detail
2175/// @endcond
2176_GLIBCXX_END_NAMESPACE_VERSION
2177} // namespace std
2178
2179#endif // _HASHTABLE_POLICY_H
constexpr complex< _Tp > operator*(const complex< _Tp > &__x, const complex< _Tp > &__y)
Return new complex value x times y.
Definition complex:400
__bool_constant< true > true_type
The type used as a compile-time boolean with true value.
Definition type_traits:111
__bool_constant< false > false_type
The type used as a compile-time boolean with false value.
Definition type_traits:114
constexpr tuple< _Elements &&... > forward_as_tuple(_Elements &&... __args) noexcept
Create a tuple of lvalue or rvalue references to the arguments.
Definition tuple:2652
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition move.h:137
constexpr piecewise_construct_t piecewise_construct
Tag for piecewise construction of std::pair objects.
Definition stl_pair.h:82
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition move.h:51
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition move.h:71
constexpr iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
ISO C++ entities toplevel namespace is std.
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
__numeric_traits_integer< _Tp > __int_traits
Convenience alias for __numeric_traits<integer-type>.
constexpr _Iterator __base(_Iterator __it)
Primary class template, tuple.
Definition tuple:837
is_empty
Definition type_traits:915
Traits class for iterators.
Uniform interface to all pointer-like types.
Definition ptr_traits.h:178
Marking input iterators.
Forward iterators support a superset of input iterator operations.
Uniform interface to C++98 and C++11 allocators.