libstdc++
hashtable_policy.h
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1// Internal policy header for unordered_set and unordered_map -*- C++ -*-
2
3// Copyright (C) 2010-2025 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
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#pragma GCC diagnostic push
66#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
67 // Helper function: return distance(first, last) for forward
68 // iterators, or 0/1 for input iterators.
69 template<typename _Iterator>
71 __distance_fw(_Iterator __first, _Iterator __last)
72 {
74 if constexpr (is_convertible<_Cat, forward_iterator_tag>::value)
75 return std::distance(__first, __last);
76 else
77 return __first != __last ? 1 : 0;
78 }
79#pragma GCC diagnostic pop
80
81 struct _Identity
82 {
83 template<typename _Tp>
84 _Tp&&
85 operator()(_Tp&& __x) const noexcept
86 { return std::forward<_Tp>(__x); }
87 };
88
89 struct _Select1st
90 {
91 template<typename _Pair>
92 struct __1st_type;
93
94 template<typename _Tp, typename _Up>
95 struct __1st_type<pair<_Tp, _Up>>
96 { using type = _Tp; };
97
98 template<typename _Tp, typename _Up>
99 struct __1st_type<const pair<_Tp, _Up>>
100 { using type = const _Tp; };
101
102 template<typename _Pair>
103 struct __1st_type<_Pair&>
104 { using type = typename __1st_type<_Pair>::type&; };
105
106 template<typename _Tp>
107 typename __1st_type<_Tp>::type&&
108 operator()(_Tp&& __x) const noexcept
109 { return std::forward<_Tp>(__x).first; }
110 };
111
112 template<typename _ExKey>
113 struct _NodeBuilder;
114
115 template<>
116 struct _NodeBuilder<_Select1st>
117 {
118 template<typename _Kt, typename _Arg, typename _NodeGenerator>
119 static auto
120 _S_build(_Kt&& __k, _Arg&& __arg, _NodeGenerator& __node_gen)
121 -> typename _NodeGenerator::__node_ptr
122 {
123 return __node_gen(std::forward<_Kt>(__k),
124 std::forward<_Arg>(__arg).second);
125 }
126 };
127
128 template<>
129 struct _NodeBuilder<_Identity>
130 {
131 template<typename _Kt, typename _Arg, typename _NodeGenerator>
132 static auto
133 _S_build(_Kt&& __k, _Arg&&, _NodeGenerator& __node_gen)
134 -> typename _NodeGenerator::__node_ptr
135 { return __node_gen(std::forward<_Kt>(__k)); }
136 };
137
138 template<typename _HashtableAlloc, typename _NodePtr>
139 struct _NodePtrGuard
140 {
141 _HashtableAlloc& _M_h;
142 _NodePtr _M_ptr;
143
144 ~_NodePtrGuard()
145 {
146 if (_M_ptr)
147 _M_h._M_deallocate_node_ptr(_M_ptr);
148 }
149 };
150
151 template<typename _NodeAlloc>
152 struct _Hashtable_alloc;
153
154 // Functor recycling a pool of nodes and using allocation once the pool is
155 // empty.
156 template<typename _NodeAlloc>
157 struct _ReuseOrAllocNode
158 {
159 private:
160 using __node_alloc_type = _NodeAlloc;
161 using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
162 using __node_alloc_traits =
163 typename __hashtable_alloc::__node_alloc_traits;
164
165 public:
166 using __node_ptr = typename __hashtable_alloc::__node_ptr;
167
168 _ReuseOrAllocNode(__node_ptr __nodes, __hashtable_alloc& __h)
169 : _M_nodes(__nodes), _M_h(__h) { }
170 _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;
171
172 ~_ReuseOrAllocNode()
173 { _M_h._M_deallocate_nodes(_M_nodes); }
174
175#pragma GCC diagnostic push
176#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
177 template<typename _Arg>
178 __node_ptr
179 operator()(_Arg&& __arg)
180 {
181 if (!_M_nodes)
182 return _M_h._M_allocate_node(std::forward<_Arg>(__arg));
183
184 using value_type = typename _NodeAlloc::value_type::value_type;
185
186 __node_ptr __node = _M_nodes;
187 if constexpr (is_assignable<value_type&, _Arg>::value)
188 {
189 __node->_M_v() = std::forward<_Arg>(__arg);
190 _M_nodes = _M_nodes->_M_next();
191 __node->_M_nxt = nullptr;
192 }
193 else
194 {
195 _M_nodes = _M_nodes->_M_next();
196 __node->_M_nxt = nullptr;
197 auto& __a = _M_h._M_node_allocator();
198 __node_alloc_traits::destroy(__a, __node->_M_valptr());
199 _NodePtrGuard<__hashtable_alloc, __node_ptr>
200 __guard{ _M_h, __node };
201 __node_alloc_traits::construct(__a, __node->_M_valptr(),
202 std::forward<_Arg>(__arg));
203 __guard._M_ptr = nullptr;
204 }
205 return __node;
206 }
207#pragma GCC diagnostic pop
208
209 private:
210 __node_ptr _M_nodes;
211 __hashtable_alloc& _M_h;
212 };
213
214 // Functor similar to the previous one but without any pool of nodes to
215 // recycle.
216 template<typename _NodeAlloc>
217 struct _AllocNode
218 {
219 private:
220 using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
221
222 public:
223 using __node_ptr = typename __hashtable_alloc::__node_ptr;
224
225 _AllocNode(__hashtable_alloc& __h)
226 : _M_h(__h) { }
227
228 template<typename... _Args>
229 __node_ptr
230 operator()(_Args&&... __args) const
231 { return _M_h._M_allocate_node(std::forward<_Args>(__args)...); }
232
233 private:
234 __hashtable_alloc& _M_h;
235 };
236
237 // Auxiliary types used for all instantiations of _Hashtable nodes
238 // and iterators.
239
240 /**
241 * struct _Hashtable_traits
242 *
243 * Important traits for hash tables.
244 *
245 * @tparam _Cache_hash_code Boolean value. True if the value of
246 * the hash function is stored along with the value. This is a
247 * time-space tradeoff. Storing it may improve lookup speed by
248 * reducing the number of times we need to call the _Hash or _Equal
249 * functors.
250 *
251 * @tparam _Constant_iterators Boolean value. True if iterator and
252 * const_iterator are both constant iterator types. This is true
253 * for unordered_set and unordered_multiset, false for
254 * unordered_map and unordered_multimap.
255 *
256 * @tparam _Unique_keys Boolean value. True if the return value
257 * of _Hashtable::count(k) is always at most one, false if it may
258 * be an arbitrary number. This is true for unordered_set and
259 * unordered_map, false for unordered_multiset and
260 * unordered_multimap.
261 */
262 template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
263 struct _Hashtable_traits
264 {
265 using __hash_cached = __bool_constant<_Cache_hash_code>;
266 using __constant_iterators = __bool_constant<_Constant_iterators>;
267 using __unique_keys = __bool_constant<_Unique_keys>;
268 };
269
270 /**
271 * struct _Hashtable_hash_traits
272 *
273 * Important traits for hash tables depending on associated hasher.
274 *
275 */
276 template<typename _Hash>
277 struct _Hashtable_hash_traits
278 {
279 static constexpr size_t
280 __small_size_threshold() noexcept
281 { return std::__is_fast_hash<_Hash>::value ? 0 : 20; }
282 };
283
284 /**
285 * struct _Hash_node_base
286 *
287 * Nodes, used to wrap elements stored in the hash table. A policy
288 * template parameter of class template _Hashtable controls whether
289 * nodes also store a hash code. In some cases (e.g. strings) this
290 * may be a performance win.
291 */
292 struct _Hash_node_base
293 {
294 _Hash_node_base* _M_nxt;
295
296 _Hash_node_base() noexcept : _M_nxt() { }
297
298 _Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
299 };
300
301 /**
302 * struct _Hash_node_value_base
303 *
304 * Node type with the value to store.
305 */
306 template<typename _Value>
307 struct _Hash_node_value_base
308 {
309 using value_type = _Value;
310
311 __gnu_cxx::__aligned_buffer<_Value> _M_storage;
312
313 [[__gnu__::__always_inline__]]
314 _Value*
315 _M_valptr() noexcept
316 { return _M_storage._M_ptr(); }
317
318 [[__gnu__::__always_inline__]]
319 const _Value*
320 _M_valptr() const noexcept
321 { return _M_storage._M_ptr(); }
322
323 [[__gnu__::__always_inline__]]
324 _Value&
325 _M_v() noexcept
326 { return *_M_valptr(); }
327
328 [[__gnu__::__always_inline__]]
329 const _Value&
330 _M_v() const noexcept
331 { return *_M_valptr(); }
332 };
333
334 /**
335 * Primary template struct _Hash_node_code_cache.
336 */
337 template<bool _Cache_hash_code>
338 struct _Hash_node_code_cache
339 { };
340
341 /**
342 * Specialization for node with cache, struct _Hash_node_code_cache.
343 */
344 template<>
345 struct _Hash_node_code_cache<true>
346 { size_t _M_hash_code; };
347
348 template<typename _Value, bool _Cache_hash_code>
349 struct _Hash_node_value
350 : _Hash_node_value_base<_Value>
351 , _Hash_node_code_cache<_Cache_hash_code>
352 { };
353
354 /**
355 * Primary template struct _Hash_node.
356 */
357 template<typename _Value, bool _Cache_hash_code>
358 struct _Hash_node
359 : _Hash_node_base
360 , _Hash_node_value<_Value, _Cache_hash_code>
361 {
362 _Hash_node*
363 _M_next() const noexcept
364 { return static_cast<_Hash_node*>(this->_M_nxt); }
365 };
366
367 /// Base class for node iterators.
368 template<typename _Value, bool _Cache_hash_code>
369 struct _Node_iterator_base
370 {
371 using __node_type = _Hash_node<_Value, _Cache_hash_code>;
372
373 __node_type* _M_cur;
374
375 _Node_iterator_base() : _M_cur(nullptr) { }
376 _Node_iterator_base(__node_type* __p) noexcept
377 : _M_cur(__p) { }
378
379 void
380 _M_incr() noexcept
381 { _M_cur = _M_cur->_M_next(); }
382
383 friend bool
384 operator==(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
385 noexcept
386 { return __x._M_cur == __y._M_cur; }
387
388#if __cpp_impl_three_way_comparison < 201907L
389 friend bool
390 operator!=(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
391 noexcept
392 { return __x._M_cur != __y._M_cur; }
393#endif
394 };
395
396 /// Node iterators, used to iterate through all the hashtable.
397 template<typename _Value, bool __constant_iterators, bool __cache>
398 struct _Node_iterator
399 : public _Node_iterator_base<_Value, __cache>
400 {
401 private:
402 using __base_type = _Node_iterator_base<_Value, __cache>;
403 using __node_type = typename __base_type::__node_type;
404
405 public:
406 using value_type = _Value;
407 using difference_type = ptrdiff_t;
408 using iterator_category = forward_iterator_tag;
409
410 using pointer = __conditional_t<__constant_iterators,
411 const value_type*, value_type*>;
412
413 using reference = __conditional_t<__constant_iterators,
414 const value_type&, value_type&>;
415
416 _Node_iterator() = default;
417
418 explicit
419 _Node_iterator(__node_type* __p) noexcept
420 : __base_type(__p) { }
421
422 reference
423 operator*() const noexcept
424 { return this->_M_cur->_M_v(); }
425
426 pointer
427 operator->() const noexcept
428 { return this->_M_cur->_M_valptr(); }
429
430 _Node_iterator&
431 operator++() noexcept
432 {
433 this->_M_incr();
434 return *this;
435 }
436
437 _Node_iterator
438 operator++(int) noexcept
439 {
440 _Node_iterator __tmp(*this);
441 this->_M_incr();
442 return __tmp;
443 }
444
445#if __cpp_impl_three_way_comparison >= 201907L
446 friend bool
447 operator==(const _Node_iterator&, const _Node_iterator&) = default;
448#else
449 friend bool
450 operator==(const _Node_iterator& __x, const _Node_iterator& __y) noexcept
451 {
452 const __base_type& __bx = __x;
453 const __base_type& __by = __y;
454 return __bx == __by;
455 }
456
457 friend bool
458 operator!=(const _Node_iterator& __x, const _Node_iterator& __y) noexcept
459 { return !(__x == __y); }
460#endif
461 };
462
463 /// Node const_iterators, used to iterate through all the hashtable.
464 template<typename _Value, bool __constant_iterators, bool __cache>
465 struct _Node_const_iterator
466 : public _Node_iterator_base<_Value, __cache>
467 {
468 private:
469 using __base_type = _Node_iterator_base<_Value, __cache>;
470 using __node_type = typename __base_type::__node_type;
471
472 // The corresponding non-const iterator.
473 using __iterator
474 = _Node_iterator<_Value, __constant_iterators, __cache>;
475
476 public:
477 using value_type = _Value;
478 using difference_type = ptrdiff_t;
479 using iterator_category = forward_iterator_tag;
480
481 using pointer = const value_type*;
482 using reference = const value_type&;
483
484 _Node_const_iterator() = default;
485
486 explicit
487 _Node_const_iterator(__node_type* __p) noexcept
488 : __base_type(__p) { }
489
490 _Node_const_iterator(const __iterator& __x) noexcept
491 : __base_type(__x._M_cur) { }
492
493 reference
494 operator*() const noexcept
495 { return this->_M_cur->_M_v(); }
496
497 pointer
498 operator->() const noexcept
499 { return this->_M_cur->_M_valptr(); }
500
501 _Node_const_iterator&
502 operator++() noexcept
503 {
504 this->_M_incr();
505 return *this;
506 }
507
508 _Node_const_iterator
509 operator++(int) noexcept
510 {
511 _Node_const_iterator __tmp(*this);
512 this->_M_incr();
513 return __tmp;
514 }
515
516#if __cpp_impl_three_way_comparison >= 201907L
517 friend bool
518 operator==(const _Node_const_iterator&,
519 const _Node_const_iterator&) = default;
520
521 friend bool
522 operator==(const _Node_const_iterator& __x, const __iterator& __y)
523 {
524 const __base_type& __bx = __x;
525 const __base_type& __by = __y;
526 return __bx == __by;
527 }
528#else
529 friend bool
530 operator==(const _Node_const_iterator& __x,
531 const _Node_const_iterator& __y) noexcept
532 {
533 const __base_type& __bx = __x;
534 const __base_type& __by = __y;
535 return __bx == __by;
536 }
537
538 friend bool
539 operator!=(const _Node_const_iterator& __x,
540 const _Node_const_iterator& __y) noexcept
541 { return !(__x == __y); }
542
543 friend bool
544 operator==(const _Node_const_iterator& __x,
545 const __iterator& __y) noexcept
546 {
547 const __base_type& __bx = __x;
548 const __base_type& __by = __y;
549 return __bx == __by;
550 }
551
552 friend bool
553 operator!=(const _Node_const_iterator& __x,
554 const __iterator& __y) noexcept
555 { return !(__x == __y); }
556
557 friend bool
558 operator==(const __iterator& __x,
559 const _Node_const_iterator& __y) noexcept
560 {
561 const __base_type& __bx = __x;
562 const __base_type& __by = __y;
563 return __bx == __by;
564 }
565
566 friend bool
567 operator!=(const __iterator& __x,
568 const _Node_const_iterator& __y) noexcept
569 { return !(__x == __y); }
570#endif
571 };
572
573 // Many of class template _Hashtable's template parameters are policy
574 // classes. These are defaults for the policies.
575
576 /// Default range hashing function: use division to fold a large number
577 /// into the range [0, N).
578 struct _Mod_range_hashing
579 {
580 size_t
581 operator()(size_t __num, size_t __den) const noexcept
582 { return __num % __den; }
583 };
584
585 /// Default ranged hash function H. In principle it should be a
586 /// function object composed from objects of type H1 and H2 such that
587 /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
588 /// h1 and h2. So instead we'll just use a tag to tell class template
589 /// hashtable to do that composition.
590 struct _Default_ranged_hash { };
591
592 /// Default value for rehash policy. Bucket size is (usually) the
593 /// smallest prime that keeps the load factor small enough.
594 struct _Prime_rehash_policy
595 {
596 using __has_load_factor = true_type;
597
598 _Prime_rehash_policy(float __z = 1.0) noexcept
599 : _M_max_load_factor(__z), _M_next_resize(0) { }
600
601 float
602 max_load_factor() const noexcept
603 { return _M_max_load_factor; }
604
605 // Return a bucket size no smaller than n.
606 // TODO: 'const' qualifier is kept for abi compatibility reason.
607 size_t
608 _M_next_bkt(size_t __n) const;
609
610 // Return a bucket count appropriate for n elements
611 size_t
612 _M_bkt_for_elements(size_t __n) const
613 { return __builtin_ceil(__n / (double)_M_max_load_factor); }
614
615 // __n_bkt is current bucket count, __n_elt is current element count,
616 // and __n_ins is number of elements to be inserted. Do we need to
617 // increase bucket count? If so, return make_pair(true, n), where n
618 // is the new bucket count. If not, return make_pair(false, 0).
619 // TODO: 'const' qualifier is kept for abi compatibility reason.
621 _M_need_rehash(size_t __n_bkt, size_t __n_elt,
622 size_t __n_ins) const;
623
624 using _State = size_t;
625
626 _State
627 _M_state() const
628 { return _M_next_resize; }
629
630 void
631 _M_reset() noexcept
632 { _M_next_resize = 0; }
633
634 void
635 _M_reset(_State __state)
636 { _M_next_resize = __state; }
637
638 static const size_t _S_growth_factor = 2;
639
640 float _M_max_load_factor;
641
642 // TODO: 'mutable' kept for abi compatibility reason.
643 mutable size_t _M_next_resize;
644 };
645
646 /// Range hashing function assuming that second arg is a power of 2.
647 struct _Mask_range_hashing
648 {
649 size_t
650 operator()(size_t __num, size_t __den) const noexcept
651 { return __num & (__den - 1); }
652 };
653
654 /// Compute closest power of 2 not less than __n
655 inline size_t
656 __clp2(size_t __n) noexcept
657 {
659 // Equivalent to return __n ? std::bit_ceil(__n) : 0;
660 if (__n < 2)
661 return __n;
662 const unsigned __lz = sizeof(size_t) > sizeof(long)
663 ? __builtin_clzll(__n - 1ull)
664 : __builtin_clzl(__n - 1ul);
665 // Doing two shifts avoids undefined behaviour when __lz == 0.
666 return (size_t(1) << (__int_traits<size_t>::__digits - __lz - 1)) << 1;
667 }
668
669 /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
670 /// operations.
671 struct _Power2_rehash_policy
672 {
673 using __has_load_factor = true_type;
674
675 _Power2_rehash_policy(float __z = 1.0) noexcept
676 : _M_max_load_factor(__z), _M_next_resize(0) { }
677
678 float
679 max_load_factor() const noexcept
680 { return _M_max_load_factor; }
681
682 // Return a bucket size no smaller than n (as long as n is not above the
683 // highest power of 2).
684 size_t
685 _M_next_bkt(size_t __n) noexcept
686 {
687 if (__n == 0)
688 // Special case on container 1st initialization with 0 bucket count
689 // hint. We keep _M_next_resize to 0 to make sure that next time we
690 // want to add an element allocation will take place.
691 return 1;
692
693 const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
694 const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
695 size_t __res = __clp2(__n);
696
697 if (__res == 0)
698 __res = __max_bkt;
699 else if (__res == 1)
700 // If __res is 1 we force it to 2 to make sure there will be an
701 // allocation so that nothing need to be stored in the initial
702 // single bucket
703 __res = 2;
704
705 if (__res == __max_bkt)
706 // Set next resize to the max value so that we never try to rehash again
707 // as we already reach the biggest possible bucket number.
708 // Note that it might result in max_load_factor not being respected.
709 _M_next_resize = size_t(-1);
710 else
711 _M_next_resize
712 = __builtin_floor(__res * (double)_M_max_load_factor);
713
714 return __res;
715 }
716
717 // Return a bucket count appropriate for n elements
718 size_t
719 _M_bkt_for_elements(size_t __n) const noexcept
720 { return __builtin_ceil(__n / (double)_M_max_load_factor); }
721
722 // __n_bkt is current bucket count, __n_elt is current element count,
723 // and __n_ins is number of elements to be inserted. Do we need to
724 // increase bucket count? If so, return make_pair(true, n), where n
725 // is the new bucket count. If not, return make_pair(false, 0).
727 _M_need_rehash(size_t __n_bkt, size_t __n_elt, size_t __n_ins) noexcept
728 {
729 if (__n_elt + __n_ins > _M_next_resize)
730 {
731 // If _M_next_resize is 0 it means that we have nothing allocated so
732 // far and that we start inserting elements. In this case we start
733 // with an initial bucket size of 11.
734 double __min_bkts
735 = std::max<size_t>(__n_elt + __n_ins, _M_next_resize ? 0 : 11)
736 / (double)_M_max_load_factor;
737 if (__min_bkts >= __n_bkt)
738 return { true,
739 _M_next_bkt(std::max<size_t>(__builtin_floor(__min_bkts) + 1,
740 __n_bkt * _S_growth_factor)) };
741
742 _M_next_resize
743 = __builtin_floor(__n_bkt * (double)_M_max_load_factor);
744 return { false, 0 };
745 }
746 else
747 return { false, 0 };
748 }
749
750 using _State = size_t;
751
752 _State
753 _M_state() const noexcept
754 { return _M_next_resize; }
755
756 void
757 _M_reset() noexcept
758 { _M_next_resize = 0; }
759
760 void
761 _M_reset(_State __state) noexcept
762 { _M_next_resize = __state; }
763
764 static const size_t _S_growth_factor = 2;
765
766 float _M_max_load_factor;
767 size_t _M_next_resize;
768 };
769
770 template<typename _RehashPolicy>
771 struct _RehashStateGuard
772 {
773 _RehashPolicy* _M_guarded_obj;
774 typename _RehashPolicy::_State _M_prev_state;
775
776 _RehashStateGuard(_RehashPolicy& __policy)
777 : _M_guarded_obj(std::__addressof(__policy))
778 , _M_prev_state(__policy._M_state())
779 { }
780 _RehashStateGuard(const _RehashStateGuard&) = delete;
781
782 ~_RehashStateGuard()
783 {
784 if (_M_guarded_obj)
785 _M_guarded_obj->_M_reset(_M_prev_state);
786 }
787 };
788
789 // Base classes for std::_Hashtable. We define these base classes
790 // because in some cases we want to do different things depending on
791 // the value of a policy class. In some cases the policy class
792 // affects which member functions and nested typedefs are defined;
793 // we handle that by specializing base class templates. Several of
794 // the base class templates need to access other members of class
795 // template _Hashtable, so we use a variant of the "Curiously
796 // Recurring Template Pattern" (CRTP) technique.
797
798 /**
799 * Primary class template _Map_base.
800 *
801 * If the hashtable has a value type of the form pair<const T1, T2> and
802 * a key extraction policy (_ExtractKey) that returns the first part
803 * of the pair, the hashtable gets a mapped_type typedef. If it
804 * satisfies those criteria and also has unique keys, then it also
805 * gets an operator[].
806 */
807 template<typename _Key, typename _Value, typename _Alloc,
808 typename _ExtractKey, typename _Equal,
809 typename _Hash, typename _RangeHash, typename _Unused,
810 typename _RehashPolicy, typename _Traits,
811 bool _Unique_keys = _Traits::__unique_keys::value>
812 struct _Map_base { };
813
814 /// Partial specialization, __unique_keys set to false, std::pair value type.
815 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
816 typename _Hash, typename _RangeHash, typename _Unused,
817 typename _RehashPolicy, typename _Traits>
818 struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
819 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
820 {
821 using mapped_type = _Val;
822 };
823
824 /// Partial specialization, __unique_keys set to true.
825 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
826 typename _Hash, typename _RangeHash, typename _Unused,
827 typename _RehashPolicy, typename _Traits>
828 struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
829 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
830 {
831 private:
832 using __hashtable_base = _Hashtable_base<_Key, pair<const _Key, _Val>,
833 _Select1st, _Equal, _Hash,
834 _RangeHash, _Unused,
835 _Traits>;
836
837 using __hashtable = _Hashtable<_Key, pair<const _Key, _Val>, _Alloc,
838 _Select1st, _Equal, _Hash, _RangeHash,
839 _Unused, _RehashPolicy, _Traits>;
840
841 using __hash_code = typename __hashtable_base::__hash_code;
842
843 public:
844 using key_type = typename __hashtable_base::key_type;
845 using mapped_type = _Val;
846
847 mapped_type&
848 operator[](const key_type& __k);
849
850 mapped_type&
851 operator[](key_type&& __k);
852
853 // _GLIBCXX_RESOLVE_LIB_DEFECTS
854 // DR 761. unordered_map needs an at() member function.
855 mapped_type&
856 at(const key_type& __k)
857 {
858 auto __ite = static_cast<__hashtable*>(this)->find(__k);
859 if (!__ite._M_cur)
860 __throw_out_of_range(__N("unordered_map::at"));
861 return __ite->second;
862 }
863
864 const mapped_type&
865 at(const key_type& __k) const
866 {
867 auto __ite = static_cast<const __hashtable*>(this)->find(__k);
868 if (!__ite._M_cur)
869 __throw_out_of_range(__N("unordered_map::at"));
870 return __ite->second;
871 }
872 };
873
874 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
875 typename _Hash, typename _RangeHash, typename _Unused,
876 typename _RehashPolicy, typename _Traits>
877 auto
878 _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
879 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
880 operator[](const key_type& __k)
881 -> mapped_type&
882 {
883 __hashtable* __h = static_cast<__hashtable*>(this);
884 __hash_code __code = __h->_M_hash_code(__k);
885 size_t __bkt = __h->_M_bucket_index(__code);
886 if (auto __node = __h->_M_find_node(__bkt, __k, __code))
887 return __node->_M_v().second;
888
889 typename __hashtable::_Scoped_node __node {
890 __h,
894 };
895 auto __pos
896 = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
897 __node._M_node = nullptr;
898 return __pos->second;
899 }
900
901 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
902 typename _Hash, typename _RangeHash, typename _Unused,
903 typename _RehashPolicy, typename _Traits>
904 auto
905 _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
906 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
907 operator[](key_type&& __k)
908 -> mapped_type&
909 {
910 __hashtable* __h = static_cast<__hashtable*>(this);
911 __hash_code __code = __h->_M_hash_code(__k);
912 size_t __bkt = __h->_M_bucket_index(__code);
913 if (auto __node = __h->_M_find_node(__bkt, __k, __code))
914 return __node->_M_v().second;
915
916 typename __hashtable::_Scoped_node __node {
917 __h,
921 };
922 auto __pos
923 = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
924 __node._M_node = nullptr;
925 return __pos->second;
926 }
927
928 // Partial specialization for unordered_map<const T, U>, see PR 104174.
929 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
930 typename _Hash, typename _RangeHash, typename _Unused,
931 typename _RehashPolicy, typename _Traits, bool __uniq>
932 struct _Map_base<const _Key, pair<const _Key, _Val>,
933 _Alloc, _Select1st, _Equal, _Hash,
934 _RangeHash, _Unused, _RehashPolicy, _Traits, __uniq>
935 : _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal, _Hash,
936 _RangeHash, _Unused, _RehashPolicy, _Traits, __uniq>
937 { };
938
939 template<typename _Policy>
940 using __has_load_factor = typename _Policy::__has_load_factor;
941
942 /**
943 * Primary class template _Rehash_base.
944 *
945 * Give hashtable the max_load_factor functions and reserve iff the
946 * rehash policy supports it.
947 */
948 template<typename _Key, typename _Value, typename _Alloc,
949 typename _ExtractKey, typename _Equal,
950 typename _Hash, typename _RangeHash, typename _Unused,
951 typename _RehashPolicy, typename _Traits,
952 typename =
953 __detected_or_t<false_type, __has_load_factor, _RehashPolicy>>
954 struct _Rehash_base;
955
956 /// Specialization when rehash policy doesn't provide load factor management.
957 template<typename _Key, typename _Value, typename _Alloc,
958 typename _ExtractKey, typename _Equal,
959 typename _Hash, typename _RangeHash, typename _Unused,
960 typename _RehashPolicy, typename _Traits>
961 struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
962 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
963 false_type /* Has load factor */>
964 {
965 };
966
967 /// Specialization when rehash policy provide load factor management.
968 template<typename _Key, typename _Value, typename _Alloc,
969 typename _ExtractKey, typename _Equal,
970 typename _Hash, typename _RangeHash, typename _Unused,
971 typename _RehashPolicy, typename _Traits>
972 struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
973 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
974 true_type /* Has load factor */>
975 {
976 private:
977 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
978 _Equal, _Hash, _RangeHash, _Unused,
979 _RehashPolicy, _Traits>;
980
981 public:
982 float
983 max_load_factor() const noexcept
984 {
985 const __hashtable* __this = static_cast<const __hashtable*>(this);
986 return __this->__rehash_policy().max_load_factor();
987 }
988
989 void
990 max_load_factor(float __z)
991 {
992 __hashtable* __this = static_cast<__hashtable*>(this);
993 __this->__rehash_policy(_RehashPolicy(__z));
994 }
995
996 void
997 reserve(size_t __n)
998 {
999 __hashtable* __this = static_cast<__hashtable*>(this);
1000 __this->rehash(__this->__rehash_policy()._M_bkt_for_elements(__n));
1001 }
1002 };
1003
1004 /**
1005 * Primary class template _Hashtable_ebo_helper.
1006 *
1007 * Helper class using [[no_unique_address]] to reduce object size.
1008 */
1009 template<typename _Tp,
1010 bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
1011 struct _Hashtable_ebo_helper
1012 {
1013 [[__no_unique_address__]] _Tp _M_obj;
1014 };
1015
1016#if ! _GLIBCXX_INLINE_VERSION
1017 // For ABI compatibility reasons, [[no_unique_address]] is only used
1018 // for empty non-final types.
1019 template<typename _Tp>
1020 struct _Hashtable_ebo_helper<_Tp, false>
1021 {
1022 _Tp _M_obj;
1023 };
1024#endif
1025
1026 /**
1027 * Primary class template _Local_iterator_base.
1028 *
1029 * Base class for local iterators, used to iterate within a bucket
1030 * but not between buckets.
1031 */
1032 template<typename _Key, typename _Value, typename _ExtractKey,
1033 typename _Hash, typename _RangeHash, typename _Unused,
1034 bool __cache_hash_code>
1035 struct _Local_iterator_base;
1036
1037 // Wraps the _Hash object and provides some utility functions for using it.
1038 template<typename _Key, typename _Value, typename _ExtractKey,
1039 typename _Hash, typename _RangeHash, typename _Unused,
1040 bool /* __cache_hash_code */>
1041 struct _Hash_code_base
1042 {
1043 // Gives the local iterator implementation access to _M_bucket_index().
1044 friend struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1045 _Hash, _RangeHash, _Unused, false>;
1046 public:
1047 using hasher = _Hash;
1048
1049 hasher
1050 hash_function() const
1051 { return _M_hash._M_obj; }
1052
1053 protected:
1054 [[__no_unique_address__]] _Hashtable_ebo_helper<_Hash> _M_hash{};
1055
1056 using __hash_code = size_t;
1057
1058 // We need the default constructor for the local iterators and _Hashtable
1059 // default constructor.
1060 _Hash_code_base() = default;
1061
1062 _Hash_code_base(const _Hash& __hash) : _M_hash{__hash} { }
1063
1064 __hash_code
1065 _M_hash_code(const _Key& __k) const
1066 {
1067 static_assert(__is_invocable<const _Hash&, const _Key&>{},
1068 "hash function must be invocable with an argument of key type");
1069 return _M_hash._M_obj(__k);
1070 }
1071
1072 template<typename _Kt>
1073 __hash_code
1074 _M_hash_code_tr(const _Kt& __k) const
1075 {
1076 static_assert(__is_invocable<const _Hash&, const _Kt&>{},
1077 "hash function must be invocable with an argument of key type");
1078 return _M_hash._M_obj(__k);
1079 }
1080
1081 __hash_code
1082 _M_hash_code(const _Hash_node_value<_Value, false>& __n) const
1083 { return _M_hash_code(_ExtractKey{}(__n._M_v())); }
1084
1085 __hash_code
1086 _M_hash_code(const _Hash_node_value<_Value, true>& __n) const
1087 { return __n._M_hash_code; }
1088
1089 size_t
1090 _M_bucket_index(__hash_code __c, size_t __bkt_count) const
1091 { return _RangeHash{}(__c, __bkt_count); }
1092
1093 size_t
1094 _M_bucket_index(const _Hash_node_value<_Value, false>& __n,
1095 size_t __bkt_count) const
1096 noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>())) )
1097 {
1098 return _RangeHash{}(_M_hash_code(_ExtractKey{}(__n._M_v())),
1099 __bkt_count);
1100 }
1101
1102 size_t
1103 _M_bucket_index(const _Hash_node_value<_Value, true>& __n,
1104 size_t __bkt_count) const noexcept
1105 { return _RangeHash{}(__n._M_hash_code, __bkt_count); }
1106
1107 void
1108 _M_store_code(_Hash_node_code_cache<false>&, __hash_code) const
1109 { }
1110
1111 void
1112 _M_copy_code(_Hash_node_code_cache<false>&,
1113 const _Hash_node_code_cache<false>&) const
1114 { }
1115
1116 void
1117 _M_store_code(_Hash_node_code_cache<true>& __n, __hash_code __c) const
1118 { __n._M_hash_code = __c; }
1119
1120 void
1121 _M_copy_code(_Hash_node_code_cache<true>& __to,
1122 const _Hash_node_code_cache<true>& __from) const
1123 { __to._M_hash_code = __from._M_hash_code; }
1124 };
1125
1126 /// Partial specialization used when nodes contain a cached hash code.
1127 template<typename _Key, typename _Value, typename _ExtractKey,
1128 typename _Hash, typename _RangeHash, typename _Unused>
1129 struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1130 _Hash, _RangeHash, _Unused, true>
1131 : public _Node_iterator_base<_Value, true>
1132 {
1133 protected:
1134 using __base_node_iter = _Node_iterator_base<_Value, true>;
1135 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1136 _Hash, _RangeHash, _Unused, true>;
1137
1138 _Local_iterator_base() = default;
1139
1140 _Local_iterator_base(const __hash_code_base&,
1141 _Hash_node<_Value, true>* __p,
1142 size_t __bkt, size_t __bkt_count)
1143 : __base_node_iter(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1144 { }
1145
1146 void
1147 _M_incr()
1148 {
1149 __base_node_iter::_M_incr();
1150 if (this->_M_cur)
1151 {
1152 size_t __bkt
1153 = _RangeHash{}(this->_M_cur->_M_hash_code, _M_bucket_count);
1154 if (__bkt != _M_bucket)
1155 this->_M_cur = nullptr;
1156 }
1157 }
1158
1159 size_t _M_bucket = 0;
1160 size_t _M_bucket_count = 0;
1161
1162 public:
1163 size_t
1164 _M_get_bucket() const { return _M_bucket; } // for debug mode
1165 };
1166
1167 // Uninitialized storage for a _Hash object in a local iterator.
1168 // This type is DefaultConstructible even if the _Hash type isn't,
1169 // so that _Local_iterator_base<..., false> can be DefaultConstructible.
1170 template<typename _Hash>
1171 struct _Hash_obj_storage
1172 {
1173 union _Uninit_storage
1174 {
1175 _Uninit_storage() noexcept { }
1176 ~_Uninit_storage() { }
1177
1178 [[__no_unique_address__]] _Hash _M_h;
1179 };
1180
1181 [[__no_unique_address__]] _Uninit_storage _M_u;
1182 };
1183
1184 // Partial specialization used when hash codes are not cached
1185 template<typename _Key, typename _Value, typename _ExtractKey,
1186 typename _Hash, typename _RangeHash, typename _Unused>
1187 struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1188 _Hash, _RangeHash, _Unused, false>
1189 : _Hash_obj_storage<_Hash>, _Node_iterator_base<_Value, false>
1190 {
1191 protected:
1192 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1193 _Hash, _RangeHash, _Unused, false>;
1194 using __hash_obj_storage = _Hash_obj_storage<_Hash>;
1195 using __node_iter_base = _Node_iterator_base<_Value, false>;
1196
1197 _Local_iterator_base() = default;
1198
1199 _Local_iterator_base(const __hash_code_base& __base,
1200 _Hash_node<_Value, false>* __p,
1201 size_t __bkt, size_t __bkt_count)
1202 : __node_iter_base(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1203 { _M_init(__base._M_hash._M_obj); }
1204
1205 ~_Local_iterator_base()
1206 {
1207 if (_M_bucket_count != size_t(-1))
1208 _M_destroy();
1209 }
1210
1211 _Local_iterator_base(const _Local_iterator_base& __iter)
1212 : __node_iter_base(__iter._M_cur), _M_bucket(__iter._M_bucket)
1213 , _M_bucket_count(__iter._M_bucket_count)
1214 {
1215 if (_M_bucket_count != size_t(-1))
1216 _M_init(__iter._M_h());
1217 }
1218
1219 _Local_iterator_base&
1220 operator=(const _Local_iterator_base& __iter)
1221 {
1222 if (_M_bucket_count != size_t(-1))
1223 _M_destroy();
1224 this->_M_cur = __iter._M_cur;
1225 _M_bucket = __iter._M_bucket;
1226 _M_bucket_count = __iter._M_bucket_count;
1227 if (_M_bucket_count != size_t(-1))
1228 _M_init(__iter._M_h());
1229 return *this;
1230 }
1231
1232 void
1233 _M_incr()
1234 {
1235 __node_iter_base::_M_incr();
1236 if (this->_M_cur)
1237 {
1238 const auto __code = _M_h()(_ExtractKey{}(this->_M_cur->_M_v()));
1239 size_t __bkt = _RangeHash{}(__code, _M_bucket_count);
1240 if (__bkt != _M_bucket)
1241 this->_M_cur = nullptr;
1242 }
1243 }
1244
1245 size_t _M_bucket = 0;
1246 size_t _M_bucket_count = -1;
1247
1248 void
1249 _M_init(const _Hash& __h)
1250 { std::_Construct(std::__addressof(__hash_obj_storage::_M_u._M_h), __h); }
1251
1252 void
1253 _M_destroy() { __hash_obj_storage::_M_u._M_h.~_Hash(); }
1254
1255 const _Hash&
1256 _M_h() const { return __hash_obj_storage::_M_u._M_h; }
1257
1258 public:
1259 size_t
1260 _M_get_bucket() const { return _M_bucket; } // for debug mode
1261 };
1262
1263 /// local iterators
1264 template<typename _Key, typename _Value, typename _ExtractKey,
1265 typename _Hash, typename _RangeHash, typename _Unused,
1266 bool __constant_iterators, bool __cache>
1267 struct _Local_iterator
1268 : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1269 _Hash, _RangeHash, _Unused, __cache>
1270 {
1271 private:
1272 using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1273 _Hash, _RangeHash, _Unused, __cache>;
1274 using __hash_code_base = typename __base_type::__hash_code_base;
1275
1276 public:
1277 using value_type = _Value;
1278 using pointer = __conditional_t<__constant_iterators,
1279 const value_type*, value_type*>;
1280 using reference = __conditional_t<__constant_iterators,
1281 const value_type&, value_type&>;
1282 using difference_type = ptrdiff_t;
1283 using iterator_category = forward_iterator_tag;
1284
1285 _Local_iterator() = default;
1286
1287 _Local_iterator(const __hash_code_base& __base,
1288 _Hash_node<_Value, __cache>* __n,
1289 size_t __bkt, size_t __bkt_count)
1290 : __base_type(__base, __n, __bkt, __bkt_count)
1291 { }
1292
1293 reference
1294 operator*() const
1295 { return this->_M_cur->_M_v(); }
1296
1297 pointer
1298 operator->() const
1299 { return this->_M_cur->_M_valptr(); }
1300
1301 _Local_iterator&
1302 operator++()
1303 {
1304 this->_M_incr();
1305 return *this;
1306 }
1307
1308 _Local_iterator
1309 operator++(int)
1310 {
1311 _Local_iterator __tmp(*this);
1312 this->_M_incr();
1313 return __tmp;
1314 }
1315 };
1316
1317 /// local const_iterators
1318 template<typename _Key, typename _Value, typename _ExtractKey,
1319 typename _Hash, typename _RangeHash, typename _Unused,
1320 bool __constant_iterators, bool __cache>
1321 struct _Local_const_iterator
1322 : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1323 _Hash, _RangeHash, _Unused, __cache>
1324 {
1325 private:
1326 using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1327 _Hash, _RangeHash, _Unused, __cache>;
1328 using __hash_code_base = typename __base_type::__hash_code_base;
1329
1330 public:
1331 using value_type = _Value;
1332 using pointer = const value_type*;
1333 using reference = const value_type&;
1334 using difference_type = ptrdiff_t;
1335 using iterator_category = forward_iterator_tag;
1336
1337 _Local_const_iterator() = default;
1338
1339 _Local_const_iterator(const __hash_code_base& __base,
1340 _Hash_node<_Value, __cache>* __n,
1341 size_t __bkt, size_t __bkt_count)
1342 : __base_type(__base, __n, __bkt, __bkt_count)
1343 { }
1344
1345 _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
1346 _Hash, _RangeHash, _Unused,
1347 __constant_iterators,
1348 __cache>& __x)
1349 : __base_type(__x)
1350 { }
1351
1352 reference
1353 operator*() const
1354 { return this->_M_cur->_M_v(); }
1355
1356 pointer
1357 operator->() const
1358 { return this->_M_cur->_M_valptr(); }
1359
1360 _Local_const_iterator&
1361 operator++()
1362 {
1363 this->_M_incr();
1364 return *this;
1365 }
1366
1367 _Local_const_iterator
1368 operator++(int)
1369 {
1370 _Local_const_iterator __tmp(*this);
1371 this->_M_incr();
1372 return __tmp;
1373 }
1374 };
1375
1376 /**
1377 * Primary class template _Hashtable_base.
1378 *
1379 * Helper class adding management of _Equal functor to
1380 * _Hash_code_base type.
1381 *
1382 * Base class templates are:
1383 * - __detail::_Hash_code_base
1384 */
1385 template<typename _Key, typename _Value, typename _ExtractKey,
1386 typename _Equal, typename _Hash, typename _RangeHash,
1387 typename _Unused, typename _Traits>
1388 struct _Hashtable_base
1389 : public _Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1390 _Unused, _Traits::__hash_cached::value>
1391 {
1392 public:
1393 using key_type = _Key;
1394 using value_type = _Value;
1395 using key_equal = _Equal;
1396 using size_type = size_t;
1397 using difference_type = ptrdiff_t;
1398
1399 using __traits_type = _Traits;
1400 using __hash_cached = typename __traits_type::__hash_cached;
1401
1402 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1403 _Hash, _RangeHash, _Unused,
1404 __hash_cached::value>;
1405
1406 using __hash_code = typename __hash_code_base::__hash_code;
1407
1408 protected:
1409 [[__no_unique_address__]] _Hashtable_ebo_helper<_Equal> _M_equal{};
1410
1411 _Hashtable_base() = default;
1412
1413 _Hashtable_base(const _Hash& __hash, const _Equal& __eq)
1414 : __hash_code_base(__hash), _M_equal{__eq}
1415 { }
1416
1417 bool
1418 _M_key_equals(const _Key& __k,
1419 const _Hash_node_value<_Value,
1420 __hash_cached::value>& __n) const
1421 {
1422 static_assert(__is_invocable<const _Equal&, const _Key&, const _Key&>{},
1423 "key equality predicate must be invocable with two arguments of "
1424 "key type");
1425 return _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1426 }
1427
1428 template<typename _Kt>
1429 bool
1430 _M_key_equals_tr(const _Kt& __k,
1431 const _Hash_node_value<_Value,
1432 __hash_cached::value>& __n) const
1433 {
1434 static_assert(
1435 __is_invocable<const _Equal&, const _Kt&, const _Key&>{},
1436 "key equality predicate must be invocable with the argument type "
1437 "and the key type");
1438 return _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1439 }
1440
1441#pragma GCC diagnostic push
1442#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
1443 bool
1444 _M_equals(const _Key& __k, __hash_code __c,
1445 const _Hash_node_value<_Value, __hash_cached::value>& __n) const
1446 {
1447 if constexpr (__hash_cached::value)
1448 if (__c != __n._M_hash_code)
1449 return false;
1450
1451 return _M_key_equals(__k, __n);
1452 }
1453
1454 template<typename _Kt>
1455 bool
1456 _M_equals_tr(const _Kt& __k, __hash_code __c,
1457 const _Hash_node_value<_Value,
1458 __hash_cached::value>& __n) const
1459 {
1460 if constexpr (__hash_cached::value)
1461 if (__c != __n._M_hash_code)
1462 return false;
1463
1464 return _M_key_equals_tr(__k, __n);
1465 }
1466
1467 bool
1468 _M_node_equals(
1469 const _Hash_node_value<_Value, __hash_cached::value>& __lhn,
1470 const _Hash_node_value<_Value, __hash_cached::value>& __rhn) const
1471 {
1472 if constexpr (__hash_cached::value)
1473 if (__lhn._M_hash_code != __rhn._M_hash_code)
1474 return false;
1475
1476 return _M_key_equals(_ExtractKey{}(__lhn._M_v()), __rhn);
1477 }
1478#pragma GCC diagnostic pop
1479
1480 const _Equal&
1481 _M_eq() const noexcept { return _M_equal._M_obj; }
1482 };
1483
1484 /**
1485 * This type deals with all allocation and keeps an allocator instance.
1486 */
1487 template<typename _NodeAlloc>
1488 struct _Hashtable_alloc
1489 {
1490 private:
1491 [[__no_unique_address__]] _Hashtable_ebo_helper<_NodeAlloc> _M_alloc{};
1492
1493 template<typename>
1494 struct __get_value_type;
1495 template<typename _Val, bool _Cache_hash_code>
1496 struct __get_value_type<_Hash_node<_Val, _Cache_hash_code>>
1497 { using type = _Val; };
1498
1499 public:
1500 using __node_type = typename _NodeAlloc::value_type;
1501 using __node_alloc_type = _NodeAlloc;
1502 // Use __gnu_cxx to benefit from _S_always_equal and al.
1503 using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
1504
1505 using __value_alloc_traits = typename __node_alloc_traits::template
1506 rebind_traits<typename __get_value_type<__node_type>::type>;
1507
1508 using __node_ptr = __node_type*;
1509 using __node_base = _Hash_node_base;
1510 using __node_base_ptr = __node_base*;
1511 using __buckets_alloc_type =
1512 __alloc_rebind<__node_alloc_type, __node_base_ptr>;
1513 using __buckets_alloc_traits = std::allocator_traits<__buckets_alloc_type>;
1514 using __buckets_ptr = __node_base_ptr*;
1515
1516 _Hashtable_alloc() = default;
1517 _Hashtable_alloc(const _Hashtable_alloc&) = default;
1518 _Hashtable_alloc(_Hashtable_alloc&&) = default;
1519
1520 template<typename _Alloc>
1521 _Hashtable_alloc(_Alloc&& __a)
1522 : _M_alloc{std::forward<_Alloc>(__a)}
1523 { }
1524
1525 __node_alloc_type&
1526 _M_node_allocator()
1527 { return _M_alloc._M_obj; }
1528
1529 const __node_alloc_type&
1530 _M_node_allocator() const
1531 { return _M_alloc._M_obj; }
1532
1533 // Allocate a node and construct an element within it.
1534 template<typename... _Args>
1535 __node_ptr
1536 _M_allocate_node(_Args&&... __args);
1537
1538 // Destroy the element within a node and deallocate the node.
1539 void
1540 _M_deallocate_node(__node_ptr __n);
1541
1542 // Deallocate a node.
1543 void
1544 _M_deallocate_node_ptr(__node_ptr __n);
1545
1546 // Deallocate the linked list of nodes pointed to by __n.
1547 // The elements within the nodes are destroyed.
1548 void
1549 _M_deallocate_nodes(__node_ptr __n);
1550
1551 __buckets_ptr
1552 _M_allocate_buckets(size_t __bkt_count);
1553
1554 void
1555 _M_deallocate_buckets(__buckets_ptr, size_t __bkt_count);
1556 };
1557
1558 // Definitions of class template _Hashtable_alloc's out-of-line member
1559 // functions.
1560 template<typename _NodeAlloc>
1561 template<typename... _Args>
1562 auto
1563 _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
1564 -> __node_ptr
1565 {
1566 auto& __alloc = _M_node_allocator();
1567 auto __nptr = __node_alloc_traits::allocate(__alloc, 1);
1568 __node_ptr __n = std::__to_address(__nptr);
1569 __try
1570 {
1571 ::new ((void*)__n) __node_type;
1572 __node_alloc_traits::construct(__alloc, __n->_M_valptr(),
1573 std::forward<_Args>(__args)...);
1574 return __n;
1575 }
1576 __catch(...)
1577 {
1578 __n->~__node_type();
1579 __node_alloc_traits::deallocate(__alloc, __nptr, 1);
1580 __throw_exception_again;
1581 }
1582 }
1583
1584 template<typename _NodeAlloc>
1585 void
1586 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_ptr __n)
1587 {
1588 __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
1589 _M_deallocate_node_ptr(__n);
1590 }
1591
1592 template<typename _NodeAlloc>
1593 void
1594 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node_ptr(__node_ptr __n)
1595 {
1596 using _Ptr = typename __node_alloc_traits::pointer;
1597 auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
1598 __n->~__node_type();
1599 __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
1600 }
1601
1602 template<typename _NodeAlloc>
1603 void
1604 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_ptr __n)
1605 {
1606 while (__n)
1607 {
1608 __node_ptr __tmp = __n;
1609 __n = __n->_M_next();
1610 _M_deallocate_node(__tmp);
1611 }
1612 }
1613
1614 template<typename _NodeAlloc>
1615 auto
1616 _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(size_t __bkt_count)
1617 -> __buckets_ptr
1618 {
1619 __buckets_alloc_type __alloc(_M_node_allocator());
1620
1621 auto __ptr = __buckets_alloc_traits::allocate(__alloc, __bkt_count);
1622 __buckets_ptr __p = std::__to_address(__ptr);
1623 __builtin_memset(__p, 0, __bkt_count * sizeof(__node_base_ptr));
1624 return __p;
1625 }
1626
1627 template<typename _NodeAlloc>
1628 void
1629 _Hashtable_alloc<_NodeAlloc>::
1630 _M_deallocate_buckets(__buckets_ptr __bkts, size_t __bkt_count)
1631 {
1632 using _Ptr = typename __buckets_alloc_traits::pointer;
1633 auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
1634 __buckets_alloc_type __alloc(_M_node_allocator());
1635 __buckets_alloc_traits::deallocate(__alloc, __ptr, __bkt_count);
1636 }
1637
1638 ///@} hashtable-detail
1639} // namespace __detail
1640/// @endcond
1641_GLIBCXX_END_NAMESPACE_VERSION
1642} // namespace std
1643
1644#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:405
__bool_constant< true > true_type
The type used as a compile-time boolean with true value.
Definition type_traits:116
__bool_constant< false > false_type
The type used as a compile-time boolean with false value.
Definition type_traits:119
constexpr tuple< _Elements &&... > forward_as_tuple(_Elements &&... __args) noexcept
Create a tuple of lvalue or rvalue references to the arguments.
Definition tuple:2678
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition move.h:138
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:52
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition move.h:72
ISO C++ entities toplevel namespace is std.
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
constexpr void _Construct(_Tp *__p, _Args &&... __args)
__numeric_traits_integer< _Tp > __int_traits
Convenience alias for __numeric_traits<integer-type>.
constexpr _Iterator __base(_Iterator __it)
Primary class template, tuple.
Definition tuple:834
Uniform interface to all allocator types.
Uniform interface to all pointer-like types.
Definition ptr_traits.h:178
Struct holding two objects of arbitrary type.
Definition stl_pair.h:286
Traits class for iterators.
Uniform interface to C++98 and C++11 allocators.