libstdc++: hashtable_policy.h Source File

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hashtable_policy.h
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1// Internal policy header for unordered_set and unordered_map -*- C++ -*-
2
3// Copyright (C) 2010-2026 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/stdexcept_throw.h>
36#include <bits/functional_hash.h> // for __is_fast_hash
37#include <bits/stl_algobase.h> // for std::min
38#include <bits/stl_pair.h> // for std::pair
39#include <ext/aligned_buffer.h> // for __gnu_cxx::__aligned_buffer
40#include <ext/alloc_traits.h> // for std::__alloc_rebind
41#include <ext/numeric_traits.h> // for __gnu_cxx::__int_traits
42
43namespace std _GLIBCXX_VISIBILITY(default)
44{
45_GLIBCXX_BEGIN_NAMESPACE_VERSION
46/// @cond undocumented
47
48 template<typename _Key, typename _Value, typename _Alloc,
49 typename _ExtractKey, typename _Equal,
50 typename _Hash, typename _RangeHash, typename _Unused,
51 typename _RehashPolicy, typename _Traits>
52 class _Hashtable;
53
54namespace __detail
55{
56 /**
57 * @defgroup hashtable-detail Base and Implementation Classes
58 * @ingroup unordered_associative_containers
59 * @{
60 */
61 template<typename _Key, typename _Value, typename _ExtractKey,
62 typename _Equal, typename _Hash, typename _RangeHash,
63 typename _Unused, typename _Traits>
64 struct _Hashtable_base;
65
66#pragma GCC diagnostic push
67#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
68 // Helper function: return distance(first, last) for forward
69 // iterators, or 0/1 for input iterators.
70 template<typename _Iterator>
71 inline typename std::iterator_traits<_Iterator>::difference_type
72 __distance_fw(_Iterator __first, _Iterator __last)
73 {
74 using _Cat = typename std::iterator_traits<_Iterator>::iterator_category;
75 if constexpr (is_convertible<_Cat, forward_iterator_tag>::value)
76 return std::distance(__first, __last);
77 else
78 return __first != __last ? 1 : 0;
79 }
80#pragma GCC diagnostic pop
81
82 struct _Identity
83 {
84 template<typename _Tp>
85 _Tp&&
86 operator()(_Tp&& __x) const noexcept
87 { return std::forward<_Tp>(__x); }
88 };
89
90 struct _Select1st
91 {
92 template<typename _Pair>
93 struct __1st_type;
94
95 template<typename _Tp, typename _Up>
96 struct __1st_type<pair<_Tp, _Up>>
97 { using type = _Tp; };
98
99 template<typename _Tp, typename _Up>
100 struct __1st_type<const pair<_Tp, _Up>>
101 { using type = const _Tp; };
102
103 template<typename _Pair>
104 struct __1st_type<_Pair&>
105 { using type = typename __1st_type<_Pair>::type&; };
106
107 template<typename _Tp>
108 typename __1st_type<_Tp>::type&&
109 operator()(_Tp&& __x) const noexcept
110 { return std::forward<_Tp>(__x).first; }
111 };
112
113 template<typename _ExKey>
114 struct _NodeBuilder;
115
116 template<>
117 struct _NodeBuilder<_Select1st>
118 {
119 template<typename _Kt, typename _Arg, typename _NodeGenerator>
120 static auto
121 _S_build(_Kt&& __k, _Arg&& __arg, _NodeGenerator& __node_gen)
122 -> typename _NodeGenerator::__node_ptr
123 {
124 return __node_gen(std::forward<_Kt>(__k),
125 std::forward<_Arg>(__arg).second);
126 }
127 };
128
129 template<>
130 struct _NodeBuilder<_Identity>
131 {
132 template<typename _Kt, typename _Arg, typename _NodeGenerator>
133 static auto
134 _S_build(_Kt&& __k, _Arg&&, _NodeGenerator& __node_gen)
135 -> typename _NodeGenerator::__node_ptr
136 { return __node_gen(std::forward<_Kt>(__k)); }
137 };
138
139 template<typename _HashtableAlloc, typename _NodePtr>
140 struct _NodePtrGuard
141 {
142 _HashtableAlloc& _M_h;
143 _NodePtr _M_ptr;
144
145 ~_NodePtrGuard()
146 {
147 if (_M_ptr)
148 _M_h._M_deallocate_node_ptr(_M_ptr);
149 }
150 };
151
152 template<typename _NodeAlloc>
153 struct _Hashtable_alloc;
154
155 // Functor recycling a pool of nodes and using allocation once the pool is
156 // empty.
157 template<typename _NodeAlloc>
158 struct _ReuseOrAllocNode
159 {
160 private:
161 using __node_alloc_type = _NodeAlloc;
162 using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
163 using __node_alloc_traits =
164 typename __hashtable_alloc::__node_alloc_traits;
165
166 public:
167 using __node_ptr = typename __hashtable_alloc::__node_ptr;
168
169 _ReuseOrAllocNode(__node_ptr __nodes, __hashtable_alloc& __h)
170 : _M_nodes(__nodes), _M_h(__h) { }
171 _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;
172
173 ~_ReuseOrAllocNode()
174 { _M_h._M_deallocate_nodes(_M_nodes); }
175
176#pragma GCC diagnostic push
177#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
178 template<typename _Arg>
179 __node_ptr
180 operator()(_Arg&& __arg)
181 {
182 if (!_M_nodes)
183 return _M_h._M_allocate_node(std::forward<_Arg>(__arg));
184
185 using value_type = typename _NodeAlloc::value_type::value_type;
186
187 __node_ptr __node = _M_nodes;
188 if constexpr (is_assignable<value_type&, _Arg>::value)
189 {
190 __node->_M_v() = std::forward<_Arg>(__arg);
191 _M_nodes = _M_nodes->_M_next();
192 __node->_M_nxt = nullptr;
193 }
194 else
195 {
196 _M_nodes = _M_nodes->_M_next();
197 __node->_M_nxt = nullptr;
198 auto& __a = _M_h._M_node_allocator();
199 __node_alloc_traits::destroy(__a, __node->_M_valptr());
200 _NodePtrGuard<__hashtable_alloc, __node_ptr>
201 __guard{ _M_h, __node };
202 __node_alloc_traits::construct(__a, __node->_M_valptr(),
203 std::forward<_Arg>(__arg));
204 __guard._M_ptr = nullptr;
205 }
206 return __node;
207 }
208#pragma GCC diagnostic pop
209
210 private:
211 __node_ptr _M_nodes;
212 __hashtable_alloc& _M_h;
213 };
214
215 // Functor similar to the previous one but without any pool of nodes to
216 // recycle.
217 template<typename _NodeAlloc>
218 struct _AllocNode
219 {
220 private:
221 using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
222
223 public:
224 using __node_ptr = typename __hashtable_alloc::__node_ptr;
225
226 _AllocNode(__hashtable_alloc& __h)
227 : _M_h(__h) { }
228
229 template<typename... _Args>
230 __node_ptr
231 operator()(_Args&&... __args) const
232 { return _M_h._M_allocate_node(std::forward<_Args>(__args)...); }
233
234 private:
235 __hashtable_alloc& _M_h;
236 };
237
238 // Auxiliary types used for all instantiations of _Hashtable nodes
239 // and iterators.
240
241 /**
242 * struct _Hashtable_traits
243 *
244 * Important traits for hash tables.
245 *
246 * @tparam _Cache_hash_code Boolean value. True if the value of
247 * the hash function is stored along with the value. This is a
248 * time-space tradeoff. Storing it may improve lookup speed by
249 * reducing the number of times we need to call the _Hash or _Equal
250 * functors.
251 *
252 * @tparam _Constant_iterators Boolean value. True if iterator and
253 * const_iterator are both constant iterator types. This is true
254 * for unordered_set and unordered_multiset, false for
255 * unordered_map and unordered_multimap.
256 *
257 * @tparam _Unique_keys Boolean value. True if the return value
258 * of _Hashtable::count(k) is always at most one, false if it may
259 * be an arbitrary number. This is true for unordered_set and
260 * unordered_map, false for unordered_multiset and
261 * unordered_multimap.
262 */
263 template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
264 struct _Hashtable_traits
265 {
266 using __hash_cached = __bool_constant<_Cache_hash_code>;
267 using __constant_iterators = __bool_constant<_Constant_iterators>;
268 using __unique_keys = __bool_constant<_Unique_keys>;
269 };
270
271 /**
272 * struct _Hashtable_hash_traits
273 *
274 * Important traits for hash tables depending on associated hasher.
275 *
276 */
277 template<typename _Hash>
278 struct _Hashtable_hash_traits
279 {
280 static constexpr size_t
281 __small_size_threshold() noexcept
282 { return std::__is_fast_hash<_Hash>::value ? 0 : 20; }
283 };
284
285 /**
286 * struct _Hash_node_base
287 *
288 * Nodes, used to wrap elements stored in the hash table. A policy
289 * template parameter of class template _Hashtable controls whether
290 * nodes also store a hash code. In some cases (e.g. strings) this
291 * may be a performance win.
292 */
293 struct _Hash_node_base
294 {
295 _Hash_node_base* _M_nxt;
296
297 _Hash_node_base() noexcept : _M_nxt() { }
298
299 _Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
300 };
301
302 /**
303 * struct _Hash_node_value_base
304 *
305 * Node type with the value to store.
306 */
307 template<typename _Value>
308 struct _Hash_node_value_base
309 {
310 using value_type = _Value;
311
312 __gnu_cxx::__aligned_buffer<_Value> _M_storage;
313
314 // These member functions must be always_inline, see PR 111050
315
316 [[__gnu__::__always_inline__]]
317 _Value*
318 _M_valptr() noexcept
319 { return _M_storage._M_ptr(); }
320
321 [[__gnu__::__always_inline__]]
322 const _Value*
323 _M_valptr() const noexcept
324 { return _M_storage._M_ptr(); }
325
326 [[__gnu__::__always_inline__]]
327 _Value&
328 _M_v() noexcept
329 { return *_M_valptr(); }
330
331 [[__gnu__::__always_inline__]]
332 const _Value&
333 _M_v() const noexcept
334 { return *_M_valptr(); }
335 };
336
337 /**
338 * Primary template struct _Hash_node_code_cache.
339 */
340 template<bool _Cache_hash_code>
341 struct _Hash_node_code_cache
342 { };
343
344 /**
345 * Specialization for node with cache, struct _Hash_node_code_cache.
346 */
347 template<>
348 struct _Hash_node_code_cache<true>
349 { size_t _M_hash_code; };
350
351 template<typename _Value, bool _Cache_hash_code>
352 struct _Hash_node_value
353 : _Hash_node_value_base<_Value>
354 , _Hash_node_code_cache<_Cache_hash_code>
355 { };
356
357 /**
358 * Primary template struct _Hash_node.
359 */
360 template<typename _Value, bool _Cache_hash_code>
361 struct _Hash_node
362 : _Hash_node_base
363 , _Hash_node_value<_Value, _Cache_hash_code>
364 {
365 _Hash_node*
366 _M_next() const noexcept
367 { return static_cast<_Hash_node*>(this->_M_nxt); }
368 };
369
370 /// Base class for node iterators.
371 template<typename _Value, bool _Cache_hash_code>
372 struct _Node_iterator_base
373 {
374 using __node_type = _Hash_node<_Value, _Cache_hash_code>;
375
376 __node_type* _M_cur;
377
378 _Node_iterator_base() : _M_cur(nullptr) { }
379 _Node_iterator_base(__node_type* __p) noexcept
380 : _M_cur(__p) { }
381
382 void
383 _M_incr() noexcept
384 { _M_cur = _M_cur->_M_next(); }
385
386 friend bool
387 operator==(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
388 noexcept
389 { return __x._M_cur == __y._M_cur; }
390
391#if __cpp_impl_three_way_comparison < 201907L
392 friend bool
393 operator!=(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
394 noexcept
395 { return __x._M_cur != __y._M_cur; }
396#endif
397 };
398
399 /// Node iterators, used to iterate through all the hashtable.
400 template<typename _Value, bool __constant_iterators, bool __cache>
401 struct _Node_iterator
402 : public _Node_iterator_base<_Value, __cache>
403 {
404 private:
405 using __base_type = _Node_iterator_base<_Value, __cache>;
406 using __node_type = typename __base_type::__node_type;
407
408 public:
409 using value_type = _Value;
410 using difference_type = ptrdiff_t;
411 using iterator_category = forward_iterator_tag;
412
413 using pointer = __conditional_t<__constant_iterators,
414 const value_type*, value_type*>;
415
416 using reference = __conditional_t<__constant_iterators,
417 const value_type&, value_type&>;
418
419 _Node_iterator() = default;
420
421 explicit
422 _Node_iterator(__node_type* __p) noexcept
423 : __base_type(__p) { }
424
425 reference
426 operator*() const noexcept
427 { return this->_M_cur->_M_v(); }
428
429 pointer
430 operator->() const noexcept
431 { return this->_M_cur->_M_valptr(); }
432
433 _Node_iterator&
434 operator++() noexcept
435 {
436 this->_M_incr();
437 return *this;
438 }
439
440 _Node_iterator
441 operator++(int) noexcept
442 {
443 _Node_iterator __tmp(*this);
444 this->_M_incr();
445 return __tmp;
446 }
447
448#if __cpp_impl_three_way_comparison >= 201907L
449 friend bool
450 operator==(const _Node_iterator&, const _Node_iterator&) = default;
451#else
452 friend bool
453 operator==(const _Node_iterator& __x, const _Node_iterator& __y) noexcept
454 {
455 const __base_type& __bx = __x;
456 const __base_type& __by = __y;
457 return __bx == __by;
458 }
459
460 friend bool
461 operator!=(const _Node_iterator& __x, const _Node_iterator& __y) noexcept
462 { return !(__x == __y); }
463#endif
464 };
465
466 /// Node const_iterators, used to iterate through all the hashtable.
467 template<typename _Value, bool __constant_iterators, bool __cache>
468 struct _Node_const_iterator
469 : public _Node_iterator_base<_Value, __cache>
470 {
471 private:
472 using __base_type = _Node_iterator_base<_Value, __cache>;
473 using __node_type = typename __base_type::__node_type;
474
475 // The corresponding non-const iterator.
476 using __iterator
477 = _Node_iterator<_Value, __constant_iterators, __cache>;
478
479 public:
480 using value_type = _Value;
481 using difference_type = ptrdiff_t;
482 using iterator_category = forward_iterator_tag;
483
484 using pointer = const value_type*;
485 using reference = const value_type&;
486
487 _Node_const_iterator() = default;
488
489 explicit
490 _Node_const_iterator(__node_type* __p) noexcept
491 : __base_type(__p) { }
492
493 _Node_const_iterator(const __iterator& __x) noexcept
494 : __base_type(__x._M_cur) { }
495
496 reference
497 operator*() const noexcept
498 { return this->_M_cur->_M_v(); }
499
500 pointer
501 operator->() const noexcept
502 { return this->_M_cur->_M_valptr(); }
503
504 _Node_const_iterator&
505 operator++() noexcept
506 {
507 this->_M_incr();
508 return *this;
509 }
510
511 _Node_const_iterator
512 operator++(int) noexcept
513 {
514 _Node_const_iterator __tmp(*this);
515 this->_M_incr();
516 return __tmp;
517 }
518
519#if __cpp_impl_three_way_comparison >= 201907L
520 friend bool
521 operator==(const _Node_const_iterator&,
522 const _Node_const_iterator&) = default;
523
524 friend bool
525 operator==(const _Node_const_iterator& __x, const __iterator& __y)
526 {
527 const __base_type& __bx = __x;
528 const __base_type& __by = __y;
529 return __bx == __by;
530 }
531#else
532 friend bool
533 operator==(const _Node_const_iterator& __x,
534 const _Node_const_iterator& __y) noexcept
535 {
536 const __base_type& __bx = __x;
537 const __base_type& __by = __y;
538 return __bx == __by;
539 }
540
541 friend bool
542 operator!=(const _Node_const_iterator& __x,
543 const _Node_const_iterator& __y) noexcept
544 { return !(__x == __y); }
545
546 friend bool
547 operator==(const _Node_const_iterator& __x,
548 const __iterator& __y) noexcept
549 {
550 const __base_type& __bx = __x;
551 const __base_type& __by = __y;
552 return __bx == __by;
553 }
554
555 friend bool
556 operator!=(const _Node_const_iterator& __x,
557 const __iterator& __y) noexcept
558 { return !(__x == __y); }
559
560 friend bool
561 operator==(const __iterator& __x,
562 const _Node_const_iterator& __y) noexcept
563 {
564 const __base_type& __bx = __x;
565 const __base_type& __by = __y;
566 return __bx == __by;
567 }
568
569 friend bool
570 operator!=(const __iterator& __x,
571 const _Node_const_iterator& __y) noexcept
572 { return !(__x == __y); }
573#endif
574 };
575
576 // Many of class template _Hashtable's template parameters are policy
577 // classes. These are defaults for the policies.
578
579 /// Default range hashing function: use division to fold a large number
580 /// into the range [0, N).
581 struct _Mod_range_hashing
582 {
583 size_t
584 operator()(size_t __num, size_t __den) const noexcept
585 { return __num % __den; }
586 };
587
588 /// Default ranged hash function H. In principle it should be a
589 /// function object composed from objects of type H1 and H2 such that
590 /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
591 /// h1 and h2. So instead we'll just use a tag to tell class template
592 /// hashtable to do that composition.
593 struct _Default_ranged_hash { };
594
595 /// Default value for rehash policy. Bucket size is (usually) the
596 /// smallest prime that keeps the load factor small enough.
597 struct _Prime_rehash_policy
598 {
599 using __has_load_factor = true_type;
600
601 _Prime_rehash_policy(float __z = 1.0) noexcept
602 : _M_max_load_factor(__z), _M_next_resize(0) { }
603
604 float
605 max_load_factor() const noexcept
606 { return _M_max_load_factor; }
607
608 // Return a bucket size no smaller than n.
609 // TODO: 'const' qualifier is kept for abi compatibility reason.
610 size_t
611 _M_next_bkt(size_t __n) const;
612
613 // Return a bucket count appropriate for n elements
614 size_t
615 _M_bkt_for_elements(size_t __n) const
616 { return __builtin_ceil(__n / (double)_M_max_load_factor); }
617
618 // __n_bkt is current bucket count, __n_elt is current element count,
619 // and __n_ins is number of elements to be inserted. Do we need to
620 // increase bucket count? If so, return make_pair(true, n), where n
621 // is the new bucket count. If not, return make_pair(false, 0).
622 // TODO: 'const' qualifier is kept for abi compatibility reason.
623 std::pair<bool, size_t>
624 _M_need_rehash(size_t __n_bkt, size_t __n_elt,
625 size_t __n_ins) const;
626
627 using _State = size_t;
628
629 _State
630 _M_state() const
631 { return _M_next_resize; }
632
633 void
634 _M_reset() noexcept
635 { _M_next_resize = 0; }
636
637 void
638 _M_reset(_State __state)
639 { _M_next_resize = __state; }
640
641 static const size_t _S_growth_factor = 2;
642
643 float _M_max_load_factor;
644
645 // TODO: 'mutable' kept for abi compatibility reason.
646 mutable size_t _M_next_resize;
647 };
648
649 /// Range hashing function assuming that second arg is a power of 2.
650 struct _Mask_range_hashing
651 {
652 size_t
653 operator()(size_t __num, size_t __den) const noexcept
654 { return __num & (__den - 1); }
655 };
656
657 /// Compute closest power of 2 not less than __n
658 inline size_t
659 __clp2(size_t __n) noexcept
660 {
661 using __gnu_cxx::__int_traits;
662 // Equivalent to return __n ? std::bit_ceil(__n) : 0;
663 if (__n < 2)
664 return __n;
665 const unsigned __lz = sizeof(size_t) > sizeof(long)
666 ? __builtin_clzll(__n - 1ull)
667 : __builtin_clzl(__n - 1ul);
668 // Doing two shifts avoids undefined behaviour when __lz == 0.
669 return (size_t(1) << (__int_traits<size_t>::__digits - __lz - 1)) << 1;
670 }
671
672 /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
673 /// operations.
674 struct _Power2_rehash_policy
675 {
676 using __has_load_factor = true_type;
677
678 _Power2_rehash_policy(float __z = 1.0) noexcept
679 : _M_max_load_factor(__z), _M_next_resize(0) { }
680
681 float
682 max_load_factor() const noexcept
683 { return _M_max_load_factor; }
684
685 // Return a bucket size no smaller than n (as long as n is not above the
686 // highest power of 2).
687 size_t
688 _M_next_bkt(size_t __n) noexcept
689 {
690 if (__n == 0)
691 // Special case on container 1st initialization with 0 bucket count
692 // hint. We keep _M_next_resize to 0 to make sure that next time we
693 // want to add an element allocation will take place.
694 return 1;
695
696 const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
697 const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
698 size_t __res = __clp2(__n);
699
700 if (__res == 0)
701 __res = __max_bkt;
702 else if (__res == 1)
703 // If __res is 1 we force it to 2 to make sure there will be an
704 // allocation so that nothing need to be stored in the initial
705 // single bucket
706 __res = 2;
707
708 if (__res == __max_bkt)
709 // Set next resize to the max value so that we never try to rehash again
710 // as we already reach the biggest possible bucket number.
711 // Note that it might result in max_load_factor not being respected.
712 _M_next_resize = size_t(-1);
713 else
714 _M_next_resize
715 = __builtin_floor(__res * (double)_M_max_load_factor);
716
717 return __res;
718 }
719
720 // Return a bucket count appropriate for n elements
721 size_t
722 _M_bkt_for_elements(size_t __n) const noexcept
723 { return __builtin_ceil(__n / (double)_M_max_load_factor); }
724
725 // __n_bkt is current bucket count, __n_elt is current element count,
726 // and __n_ins is number of elements to be inserted. Do we need to
727 // increase bucket count? If so, return make_pair(true, n), where n
728 // is the new bucket count. If not, return make_pair(false, 0).
729 std::pair<bool, size_t>
730 _M_need_rehash(size_t __n_bkt, size_t __n_elt, size_t __n_ins) noexcept
731 {
732 if (__n_elt + __n_ins > _M_next_resize)
733 {
734 // If _M_next_resize is 0 it means that we have nothing allocated so
735 // far and that we start inserting elements. In this case we start
736 // with an initial bucket size of 11.
737 double __min_bkts
738 = std::max<size_t>(__n_elt + __n_ins, _M_next_resize ? 0 : 11)
739 / (double)_M_max_load_factor;
740 if (__min_bkts >= __n_bkt)
741 return { true,
742 _M_next_bkt(std::max<size_t>(__builtin_floor(__min_bkts) + 1,
743 __n_bkt * _S_growth_factor)) };
744
745 _M_next_resize
746 = __builtin_floor(__n_bkt * (double)_M_max_load_factor);
747 return { false, 0 };
748 }
749 else
750 return { false, 0 };
751 }
752
753 using _State = size_t;
754
755 _State
756 _M_state() const noexcept
757 { return _M_next_resize; }
758
759 void
760 _M_reset() noexcept
761 { _M_next_resize = 0; }
762
763 void
764 _M_reset(_State __state) noexcept
765 { _M_next_resize = __state; }
766
767 static const size_t _S_growth_factor = 2;
768
769 float _M_max_load_factor;
770 size_t _M_next_resize;
771 };
772
773 template<typename _RehashPolicy>
774 struct _RehashStateGuard
775 {
776 _RehashPolicy* _M_guarded_obj;
777 typename _RehashPolicy::_State _M_prev_state;
778
779 _RehashStateGuard(_RehashPolicy& __policy)
780 : _M_guarded_obj(std::addressof(__policy))
781 , _M_prev_state(__policy._M_state())
782 { }
783 _RehashStateGuard(const _RehashStateGuard&) = delete;
784
785 ~_RehashStateGuard()
786 {
787 if (_M_guarded_obj)
788 _M_guarded_obj->_M_reset(_M_prev_state);
789 }
790 };
791
792 // Base classes for std::_Hashtable. We define these base classes
793 // because in some cases we want to do different things depending on
794 // the value of a policy class. In some cases the policy class
795 // affects which member functions and nested typedefs are defined;
796 // we handle that by specializing base class templates. Several of
797 // the base class templates need to access other members of class
798 // template _Hashtable, so we use a variant of the "Curiously
799 // Recurring Template Pattern" (CRTP) technique.
800
801 /**
802 * Primary class template _Map_base.
803 *
804 * If the hashtable has a value type of the form pair<const T1, T2> and
805 * a key extraction policy (_ExtractKey) that returns the first part
806 * of the pair, the hashtable gets a mapped_type typedef. If it
807 * satisfies those criteria and also has unique keys, then it also
808 * gets an operator[].
809 */
810 template<typename _Key, typename _Value, typename _Alloc,
811 typename _ExtractKey, typename _Equal,
812 typename _Hash, typename _RangeHash, typename _Unused,
813 typename _RehashPolicy, typename _Traits,
814 bool _Unique_keys = _Traits::__unique_keys::value>
815 struct _Map_base { };
816
817 /// Partial specialization, __unique_keys set to false, std::pair value type.
818 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
819 typename _Hash, typename _RangeHash, typename _Unused,
820 typename _RehashPolicy, typename _Traits>
821 struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
822 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
823 {
824 using mapped_type = _Val;
825 };
826
827 /// Partial specialization, __unique_keys set to true.
828 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
829 typename _Hash, typename _RangeHash, typename _Unused,
830 typename _RehashPolicy, typename _Traits>
831 struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
832 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
833 {
834 private:
835 using __hashtable_base = _Hashtable_base<_Key, pair<const _Key, _Val>,
836 _Select1st, _Equal, _Hash,
837 _RangeHash, _Unused,
838 _Traits>;
839
840 using __hashtable = _Hashtable<_Key, pair<const _Key, _Val>, _Alloc,
841 _Select1st, _Equal, _Hash, _RangeHash,
842 _Unused, _RehashPolicy, _Traits>;
843
844 using __hash_code = typename __hashtable_base::__hash_code;
845
846 public:
847 using key_type = typename __hashtable_base::key_type;
848 using mapped_type = _Val;
849
850 mapped_type&
851 operator[](const key_type& __k);
852
853 mapped_type&
854 operator[](key_type&& __k);
855
856 // _GLIBCXX_RESOLVE_LIB_DEFECTS
857 // DR 761. unordered_map needs an at() member function.
858 mapped_type&
859 at(const key_type& __k)
860 {
861 auto __ite = static_cast<__hashtable*>(this)->find(__k);
862 if (!__ite._M_cur)
863 __throw_out_of_range(__N("unordered_map::at"));
864 return __ite->second;
865 }
866
867 const mapped_type&
868 at(const key_type& __k) const
869 {
870 auto __ite = static_cast<const __hashtable*>(this)->find(__k);
871 if (!__ite._M_cur)
872 __throw_out_of_range(__N("unordered_map::at"));
873 return __ite->second;
874 }
875
876 template <typename _Kt>
877 mapped_type&
878 _M_at_tr(const _Kt& __k)
879 {
880 auto __ite = static_cast<__hashtable*>(this)->_M_find_tr(__k);
881 if (!__ite._M_cur)
882 __throw_out_of_range(__N("unordered_map::at"));
883 return __ite->second;
884 }
885
886 template <typename _Kt>
887 const mapped_type&
888 _M_at_tr(const _Kt& __k) const
889 {
890 auto __ite = static_cast<const __hashtable*>(this)->_M_find_tr(__k);
891 if (!__ite._M_cur)
892 __throw_out_of_range(__N("unordered_map::at"));
893 return __ite->second;
894 }
895 };
896
897 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
898 typename _Hash, typename _RangeHash, typename _Unused,
899 typename _RehashPolicy, typename _Traits>
900 auto
901 _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
902 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
903 operator[](const key_type& __k)
904 -> mapped_type&
905 {
906 __hashtable* __h = static_cast<__hashtable*>(this);
907 __hash_code __code = __h->_M_hash_code(__k);
908 size_t __bkt = __h->_M_bucket_index(__code);
909 if (auto __node = __h->_M_find_node(__bkt, __k, __code))
910 return __node->_M_v().second;
911
912 typename __hashtable::_Scoped_node __node {
913 __h,
914 std::piecewise_construct,
915 std::tuple<const key_type&>(__k),
916 std::tuple<>()
917 };
918 auto __pos
919 = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
920 __node._M_node = nullptr;
921 return __pos->second;
922 }
923
924 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
925 typename _Hash, typename _RangeHash, typename _Unused,
926 typename _RehashPolicy, typename _Traits>
927 auto
928 _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
929 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
930 operator[](key_type&& __k)
931 -> mapped_type&
932 {
933 __hashtable* __h = static_cast<__hashtable*>(this);
934 __hash_code __code = __h->_M_hash_code(__k);
935 size_t __bkt = __h->_M_bucket_index(__code);
936 if (auto __node = __h->_M_find_node(__bkt, __k, __code))
937 return __node->_M_v().second;
938
939 typename __hashtable::_Scoped_node __node {
940 __h,
941 std::piecewise_construct,
942 std::forward_as_tuple(std::move(__k)),
943 std::tuple<>()
944 };
945 auto __pos
946 = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
947 __node._M_node = nullptr;
948 return __pos->second;
949 }
950
951 // Partial specialization for unordered_map<const T, U>, see PR 104174.
952 template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
953 typename _Hash, typename _RangeHash, typename _Unused,
954 typename _RehashPolicy, typename _Traits, bool __uniq>
955 struct _Map_base<const _Key, pair<const _Key, _Val>,
956 _Alloc, _Select1st, _Equal, _Hash,
957 _RangeHash, _Unused, _RehashPolicy, _Traits, __uniq>
958 : _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal, _Hash,
959 _RangeHash, _Unused, _RehashPolicy, _Traits, __uniq>
960 { };
961
962 template<typename _Policy>
963 using __has_load_factor = typename _Policy::__has_load_factor;
964
965 /**
966 * Primary class template _Rehash_base.
967 *
968 * Give hashtable the max_load_factor functions and reserve iff the
969 * rehash policy supports it.
970 */
971 template<typename _Key, typename _Value, typename _Alloc,
972 typename _ExtractKey, typename _Equal,
973 typename _Hash, typename _RangeHash, typename _Unused,
974 typename _RehashPolicy, typename _Traits,
975 typename =
976 __detected_or_t<false_type, __has_load_factor, _RehashPolicy>>
977 struct _Rehash_base;
978
979 /// Specialization when rehash policy doesn't provide load factor management.
980 template<typename _Key, typename _Value, typename _Alloc,
981 typename _ExtractKey, typename _Equal,
982 typename _Hash, typename _RangeHash, typename _Unused,
983 typename _RehashPolicy, typename _Traits>
984 struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
985 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
986 false_type /* Has load factor */>
987 {
988 };
989
990 /// Specialization when rehash policy provide load factor management.
991 template<typename _Key, typename _Value, typename _Alloc,
992 typename _ExtractKey, typename _Equal,
993 typename _Hash, typename _RangeHash, typename _Unused,
994 typename _RehashPolicy, typename _Traits>
995 struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
996 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
997 true_type /* Has load factor */>
998 {
999 private:
1000 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
1001 _Equal, _Hash, _RangeHash, _Unused,
1002 _RehashPolicy, _Traits>;
1003
1004 public:
1005 float
1006 max_load_factor() const noexcept
1007 {
1008 const __hashtable* __this = static_cast<const __hashtable*>(this);
1009 return __this->__rehash_policy().max_load_factor();
1010 }
1011
1012 void
1013 max_load_factor(float __z)
1014 {
1015 __hashtable* __this = static_cast<__hashtable*>(this);
1016 __this->__rehash_policy(_RehashPolicy(__z));
1017 }
1018
1019 void
1020 reserve(size_t __n)
1021 {
1022 __hashtable* __this = static_cast<__hashtable*>(this);
1023 __this->rehash(__this->__rehash_policy()._M_bkt_for_elements(__n));
1024 }
1025 };
1026
1027 /**
1028 * Primary class template _Hashtable_ebo_helper.
1029 *
1030 * Helper class using [[no_unique_address]] to reduce object size.
1031 */
1032 template<typename _Tp,
1033 bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
1034 struct _Hashtable_ebo_helper
1035 {
1036 [[__no_unique_address__]] _Tp _M_obj;
1037 };
1038
1039#if ! _GLIBCXX_INLINE_VERSION
1040 // For ABI compatibility reasons, [[no_unique_address]] is only used
1041 // for empty non-final types.
1042 template<typename _Tp>
1043 struct _Hashtable_ebo_helper<_Tp, false>
1044 {
1045 _Tp _M_obj;
1046 };
1047#endif
1048
1049 /**
1050 * Primary class template _Local_iterator_base.
1051 *
1052 * Base class for local iterators, used to iterate within a bucket
1053 * but not between buckets.
1054 */
1055 template<typename _Key, typename _Value, typename _ExtractKey,
1056 typename _Hash, typename _RangeHash, typename _Unused,
1057 bool __cache_hash_code>
1058 struct _Local_iterator_base;
1059
1060 // Wraps the _Hash object and provides some utility functions for using it.
1061 template<typename _Key, typename _Value, typename _ExtractKey,
1062 typename _Hash, typename _RangeHash, typename _Unused,
1063 bool /* __cache_hash_code */>
1064 struct _Hash_code_base
1065 {
1066 // Gives the local iterator implementation access to _M_bucket_index().
1067 friend struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1068 _Hash, _RangeHash, _Unused, false>;
1069 public:
1070 using hasher = _Hash;
1071
1072 hasher
1073 hash_function() const
1074 { return _M_hash._M_obj; }
1075
1076 protected:
1077 [[__no_unique_address__]] _Hashtable_ebo_helper<_Hash> _M_hash{};
1078
1079 using __hash_code = size_t;
1080
1081 // We need the default constructor for the local iterators and _Hashtable
1082 // default constructor.
1083 _Hash_code_base() = default;
1084
1085 _Hash_code_base(const _Hash& __hash) : _M_hash{__hash} { }
1086
1087 __hash_code
1088 _M_hash_code(const _Key& __k) const
1089 {
1090 static_assert(__is_invocable<const _Hash&, const _Key&>{},
1091 "hash function must be invocable with an argument of key type");
1092 return _M_hash._M_obj(__k);
1093 }
1094
1095 template<typename _Kt>
1096 __hash_code
1097 _M_hash_code_tr(const _Kt& __k) const
1098 {
1099 static_assert(__is_invocable<const _Hash&, const _Kt&>{},
1100 "hash function must be invocable with an argument of key type");
1101 return _M_hash._M_obj(__k);
1102 }
1103
1104 __hash_code
1105 _M_hash_code(const _Hash_node_value<_Value, false>& __n) const
1106 { return _M_hash_code(_ExtractKey{}(__n._M_v())); }
1107
1108 __hash_code
1109 _M_hash_code(const _Hash_node_value<_Value, true>& __n) const
1110 { return __n._M_hash_code; }
1111
1112 size_t
1113 _M_bucket_index(__hash_code __c, size_t __bkt_count) const
1114 { return _RangeHash{}(__c, __bkt_count); }
1115
1116 size_t
1117 _M_bucket_index(const _Hash_node_value<_Value, false>& __n,
1118 size_t __bkt_count) const
1119 noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>())) )
1120 {
1121 return _RangeHash{}(_M_hash_code(_ExtractKey{}(__n._M_v())),
1122 __bkt_count);
1123 }
1124
1125 size_t
1126 _M_bucket_index(const _Hash_node_value<_Value, true>& __n,
1127 size_t __bkt_count) const noexcept
1128 { return _RangeHash{}(__n._M_hash_code, __bkt_count); }
1129 };
1130
1131 /// Partial specialization used when nodes contain a cached hash code.
1132 template<typename _Key, typename _Value, typename _ExtractKey,
1133 typename _Hash, typename _RangeHash, typename _Unused>
1134 struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1135 _Hash, _RangeHash, _Unused, true>
1136 : public _Node_iterator_base<_Value, true>
1137 {
1138 protected:
1139 using __base_node_iter = _Node_iterator_base<_Value, true>;
1140 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1141 _Hash, _RangeHash, _Unused, true>;
1142
1143 _Local_iterator_base() = default;
1144
1145 _Local_iterator_base(const __hash_code_base&,
1146 _Hash_node<_Value, true>* __p,
1147 size_t __bkt, size_t __bkt_count)
1148 : __base_node_iter(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1149 { }
1150
1151 void
1152 _M_incr()
1153 {
1154 __base_node_iter::_M_incr();
1155 if (this->_M_cur)
1156 {
1157 size_t __bkt
1158 = _RangeHash{}(this->_M_cur->_M_hash_code, _M_bucket_count);
1159 if (__bkt != _M_bucket)
1160 this->_M_cur = nullptr;
1161 }
1162 }
1163
1164 size_t _M_bucket = 0;
1165 size_t _M_bucket_count = 0;
1166
1167 public:
1168 size_t
1169 _M_get_bucket() const { return _M_bucket; } // for debug mode
1170 };
1171
1172 // Uninitialized storage for a _Hash object in a local iterator.
1173 // This type is DefaultConstructible even if the _Hash type isn't,
1174 // so that _Local_iterator_base<..., false> can be DefaultConstructible.
1175 template<typename _Hash>
1176 struct _Hash_obj_storage
1177 {
1178 union _Uninit_storage
1179 {
1180 _Uninit_storage() noexcept { }
1181 ~_Uninit_storage() { }
1182
1183 [[__no_unique_address__]] _Hash _M_h;
1184 };
1185
1186 [[__no_unique_address__]] _Uninit_storage _M_u;
1187 };
1188
1189 // Partial specialization used when hash codes are not cached
1190 template<typename _Key, typename _Value, typename _ExtractKey,
1191 typename _Hash, typename _RangeHash, typename _Unused>
1192 struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1193 _Hash, _RangeHash, _Unused, false>
1194 : _Hash_obj_storage<_Hash>, _Node_iterator_base<_Value, false>
1195 {
1196 protected:
1197 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1198 _Hash, _RangeHash, _Unused, false>;
1199 using __hash_obj_storage = _Hash_obj_storage<_Hash>;
1200 using __node_iter_base = _Node_iterator_base<_Value, false>;
1201
1202 _Local_iterator_base() = default;
1203
1204 _Local_iterator_base(const __hash_code_base& __base,
1205 _Hash_node<_Value, false>* __p,
1206 size_t __bkt, size_t __bkt_count)
1207 : __node_iter_base(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1208 { _M_init(__base._M_hash._M_obj); }
1209
1210 ~_Local_iterator_base()
1211 {
1212 if (_M_bucket_count != size_t(-1))
1213 _M_destroy();
1214 }
1215
1216 _Local_iterator_base(const _Local_iterator_base& __iter)
1217 : __node_iter_base(__iter._M_cur), _M_bucket(__iter._M_bucket)
1218 , _M_bucket_count(__iter._M_bucket_count)
1219 {
1220 if (_M_bucket_count != size_t(-1))
1221 _M_init(__iter._M_h());
1222 }
1223
1224 _Local_iterator_base&
1225 operator=(const _Local_iterator_base& __iter)
1226 {
1227 if (_M_bucket_count != size_t(-1))
1228 _M_destroy();
1229 this->_M_cur = __iter._M_cur;
1230 _M_bucket = __iter._M_bucket;
1231 _M_bucket_count = __iter._M_bucket_count;
1232 if (_M_bucket_count != size_t(-1))
1233 _M_init(__iter._M_h());
1234 return *this;
1235 }
1236
1237 void
1238 _M_incr()
1239 {
1240 __node_iter_base::_M_incr();
1241 if (this->_M_cur)
1242 {
1243 const auto __code = _M_h()(_ExtractKey{}(this->_M_cur->_M_v()));
1244 size_t __bkt = _RangeHash{}(__code, _M_bucket_count);
1245 if (__bkt != _M_bucket)
1246 this->_M_cur = nullptr;
1247 }
1248 }
1249
1250 size_t _M_bucket = 0;
1251 size_t _M_bucket_count = -1;
1252
1253 void
1254 _M_init(const _Hash& __h)
1255 { std::_Construct(std::addressof(__hash_obj_storage::_M_u._M_h), __h); }
1256
1257 void
1258 _M_destroy() { __hash_obj_storage::_M_u._M_h.~_Hash(); }
1259
1260 const _Hash&
1261 _M_h() const { return __hash_obj_storage::_M_u._M_h; }
1262
1263 public:
1264 size_t
1265 _M_get_bucket() const { return _M_bucket; } // for debug mode
1266 };
1267
1268 /// local iterators
1269 template<typename _Key, typename _Value, typename _ExtractKey,
1270 typename _Hash, typename _RangeHash, typename _Unused,
1271 bool __constant_iterators, bool __cache>
1272 struct _Local_iterator
1273 : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1274 _Hash, _RangeHash, _Unused, __cache>
1275 {
1276 private:
1277 using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1278 _Hash, _RangeHash, _Unused, __cache>;
1279 using __hash_code_base = typename __base_type::__hash_code_base;
1280
1281 public:
1282 using value_type = _Value;
1283 using pointer = __conditional_t<__constant_iterators,
1284 const value_type*, value_type*>;
1285 using reference = __conditional_t<__constant_iterators,
1286 const value_type&, value_type&>;
1287 using difference_type = ptrdiff_t;
1288 using iterator_category = forward_iterator_tag;
1289
1290 _Local_iterator() = default;
1291
1292 _Local_iterator(const __hash_code_base& __base,
1293 _Hash_node<_Value, __cache>* __n,
1294 size_t __bkt, size_t __bkt_count)
1295 : __base_type(__base, __n, __bkt, __bkt_count)
1296 { }
1297
1298 reference
1299 operator*() const
1300 { return this->_M_cur->_M_v(); }
1301
1302 pointer
1303 operator->() const
1304 { return this->_M_cur->_M_valptr(); }
1305
1306 _Local_iterator&
1307 operator++()
1308 {
1309 this->_M_incr();
1310 return *this;
1311 }
1312
1313 _Local_iterator
1314 operator++(int)
1315 {
1316 _Local_iterator __tmp(*this);
1317 this->_M_incr();
1318 return __tmp;
1319 }
1320 };
1321
1322 /// local const_iterators
1323 template<typename _Key, typename _Value, typename _ExtractKey,
1324 typename _Hash, typename _RangeHash, typename _Unused,
1325 bool __constant_iterators, bool __cache>
1326 struct _Local_const_iterator
1327 : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1328 _Hash, _RangeHash, _Unused, __cache>
1329 {
1330 private:
1331 using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1332 _Hash, _RangeHash, _Unused, __cache>;
1333 using __hash_code_base = typename __base_type::__hash_code_base;
1334
1335 public:
1336 using value_type = _Value;
1337 using pointer = const value_type*;
1338 using reference = const value_type&;
1339 using difference_type = ptrdiff_t;
1340 using iterator_category = forward_iterator_tag;
1341
1342 _Local_const_iterator() = default;
1343
1344 _Local_const_iterator(const __hash_code_base& __base,
1345 _Hash_node<_Value, __cache>* __n,
1346 size_t __bkt, size_t __bkt_count)
1347 : __base_type(__base, __n, __bkt, __bkt_count)
1348 { }
1349
1350 _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
1351 _Hash, _RangeHash, _Unused,
1352 __constant_iterators,
1353 __cache>& __x)
1354 : __base_type(__x)
1355 { }
1356
1357 reference
1358 operator*() const
1359 { return this->_M_cur->_M_v(); }
1360
1361 pointer
1362 operator->() const
1363 { return this->_M_cur->_M_valptr(); }
1364
1365 _Local_const_iterator&
1366 operator++()
1367 {
1368 this->_M_incr();
1369 return *this;
1370 }
1371
1372 _Local_const_iterator
1373 operator++(int)
1374 {
1375 _Local_const_iterator __tmp(*this);
1376 this->_M_incr();
1377 return __tmp;
1378 }
1379 };
1380
1381 /**
1382 * Primary class template _Hashtable_base.
1383 *
1384 * Helper class adding management of _Equal functor to
1385 * _Hash_code_base type.
1386 *
1387 * Base class templates are:
1388 * - __detail::_Hash_code_base
1389 */
1390 template<typename _Key, typename _Value, typename _ExtractKey,
1391 typename _Equal, typename _Hash, typename _RangeHash,
1392 typename _Unused, typename _Traits>
1393 struct _Hashtable_base
1394 : public _Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1395 _Unused, _Traits::__hash_cached::value>
1396 {
1397 public:
1398 using key_type = _Key;
1399 using value_type = _Value;
1400 using key_equal = _Equal;
1401 using size_type = size_t;
1402 using difference_type = ptrdiff_t;
1403
1404 using __traits_type = _Traits;
1405 using __hash_cached = typename __traits_type::__hash_cached;
1406
1407 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1408 _Hash, _RangeHash, _Unused,
1409 __hash_cached::value>;
1410
1411 using __hash_code = typename __hash_code_base::__hash_code;
1412
1413 protected:
1414 [[__no_unique_address__]] _Hashtable_ebo_helper<_Equal> _M_equal{};
1415
1416 _Hashtable_base() = default;
1417
1418 _Hashtable_base(const _Hash& __hash, const _Equal& __eq)
1419 : __hash_code_base(__hash), _M_equal{__eq}
1420 { }
1421
1422 bool
1423 _M_key_equals(const _Key& __k,
1424 const _Hash_node_value<_Value,
1425 __hash_cached::value>& __n) const
1426 {
1427 static_assert(__is_invocable<const _Equal&, const _Key&, const _Key&>{},
1428 "key equality predicate must be invocable with two arguments of "
1429 "key type");
1430 return _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1431 }
1432
1433 template<typename _Kt>
1434 bool
1435 _M_key_equals_tr(const _Kt& __k,
1436 const _Hash_node_value<_Value, __hash_cached::value>& __n) const
1437 {
1438 static_assert(
1439 __is_invocable<const _Equal&, const _Kt&, const _Key&>{},
1440 "key equality predicate must be invocable with the argument type "
1441 "and the key type");
1442 return _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1443 }
1444
1445#pragma GCC diagnostic push
1446#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
1447 bool
1448 _M_equals(const _Key& __k, __hash_code __c,
1449 const _Hash_node_value<_Value, __hash_cached::value>& __n) const
1450 {
1451 if constexpr (__hash_cached::value)
1452 if (__c != __n._M_hash_code)
1453 return false;
1454
1455 return _M_key_equals(__k, __n);
1456 }
1457
1458 template<typename _Kt>
1459 bool
1460 _M_equals_tr(const _Kt& __k, __hash_code __c,
1461 const _Hash_node_value<_Value, __hash_cached::value>& __n) const
1462 {
1463 if constexpr (__hash_cached::value)
1464 if (__c != __n._M_hash_code)
1465 return false;
1466
1467 return _M_key_equals_tr(__k, __n);
1468 }
1469
1470 bool
1471 _M_node_equals(
1472 const _Hash_node_value<_Value, __hash_cached::value>& __lhn,
1473 const _Hash_node_value<_Value, __hash_cached::value>& __rhn) const
1474 {
1475 if constexpr (__hash_cached::value)
1476 if (__lhn._M_hash_code != __rhn._M_hash_code)
1477 return false;
1478
1479 return _M_key_equals(_ExtractKey{}(__lhn._M_v()), __rhn);
1480 }
1481#pragma GCC diagnostic pop
1482
1483 const _Equal&
1484 _M_eq() const noexcept { return _M_equal._M_obj; }
1485 };
1486
1487 /**
1488 * This type deals with all allocation and keeps an allocator instance.
1489 */
1490 template<typename _NodeAlloc>
1491 struct _Hashtable_alloc
1492 {
1493 private:
1494 [[__no_unique_address__]] _Hashtable_ebo_helper<_NodeAlloc> _M_alloc{};
1495
1496 template<typename>
1497 struct __get_value_type;
1498 template<typename _Val, bool _Cache_hash_code>
1499 struct __get_value_type<_Hash_node<_Val, _Cache_hash_code>>
1500 { using type = _Val; };
1501
1502 public:
1503 using __node_type = typename _NodeAlloc::value_type;
1504 using __node_alloc_type = _NodeAlloc;
1505 // Use __gnu_cxx to benefit from _S_always_equal and al.
1506 using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
1507
1508 using __value_alloc_traits = typename __node_alloc_traits::template
1509 rebind_traits<typename __get_value_type<__node_type>::type>;
1510
1511 using __node_ptr = __node_type*;
1512 using __node_base = _Hash_node_base;
1513 using __node_base_ptr = __node_base*;
1514 using __buckets_alloc_type =
1515 __alloc_rebind<__node_alloc_type, __node_base_ptr>;
1516 using __buckets_alloc_traits = std::allocator_traits<__buckets_alloc_type>;
1517 using __buckets_ptr = __node_base_ptr*;
1518
1519 _Hashtable_alloc() = default;
1520 _Hashtable_alloc(const _Hashtable_alloc&) = default;
1521 _Hashtable_alloc(_Hashtable_alloc&&) = default;
1522
1523 template<typename _Alloc>
1524 _Hashtable_alloc(_Alloc&& __a)
1525 : _M_alloc{std::forward<_Alloc>(__a)}
1526 { }
1527
1528 __node_alloc_type&
1529 _M_node_allocator()
1530 { return _M_alloc._M_obj; }
1531
1532 const __node_alloc_type&
1533 _M_node_allocator() const
1534 { return _M_alloc._M_obj; }
1535
1536 // Allocate a node and construct an element within it.
1537 template<typename... _Args>
1538 __node_ptr
1539 _M_allocate_node(_Args&&... __args);
1540
1541 // Destroy the element within a node and deallocate the node.
1542 void
1543 _M_deallocate_node(__node_ptr __n);
1544
1545 // Deallocate a node.
1546 void
1547 _M_deallocate_node_ptr(__node_ptr __n);
1548
1549 // Deallocate the linked list of nodes pointed to by __n.
1550 // The elements within the nodes are destroyed.
1551 void
1552 _M_deallocate_nodes(__node_ptr __n);
1553
1554 __buckets_ptr
1555 _M_allocate_buckets(size_t __bkt_count);
1556
1557 void
1558 _M_deallocate_buckets(__buckets_ptr, size_t __bkt_count);
1559 };
1560
1561 // Definitions of class template _Hashtable_alloc's out-of-line member
1562 // functions.
1563 template<typename _NodeAlloc>
1564 template<typename... _Args>
1565 auto
1566 _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
1567 -> __node_ptr
1568 {
1569 auto& __alloc = _M_node_allocator();
1570 auto __nptr = __node_alloc_traits::allocate(__alloc, 1);
1571 __node_ptr __n = std::__to_address(__nptr);
1572 __try
1573 {
1574 ::new ((void*)__n) __node_type;
1575 __node_alloc_traits::construct(__alloc, __n->_M_valptr(),
1576 std::forward<_Args>(__args)...);
1577 return __n;
1578 }
1579 __catch(...)
1580 {
1581 __n->~__node_type();
1582 __node_alloc_traits::deallocate(__alloc, __nptr, 1);
1583 __throw_exception_again;
1584 }
1585 }
1586
1587 template<typename _NodeAlloc>
1588 void
1589 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_ptr __n)
1590 {
1591 __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
1592 _M_deallocate_node_ptr(__n);
1593 }
1594
1595 template<typename _NodeAlloc>
1596 void
1597 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node_ptr(__node_ptr __n)
1598 {
1599 using _Ptr = typename __node_alloc_traits::pointer;
1600 auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
1601 __n->~__node_type();
1602 __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
1603 }
1604
1605 template<typename _NodeAlloc>
1606 void
1607 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_ptr __n)
1608 {
1609 while (__n)
1610 {
1611 __node_ptr __tmp = __n;
1612 __n = __n->_M_next();
1613 _M_deallocate_node(__tmp);
1614 }
1615 }
1616
1617 template<typename _NodeAlloc>
1618 auto
1619 _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(size_t __bkt_count)
1620 -> __buckets_ptr
1621 {
1622 __buckets_alloc_type __alloc(_M_node_allocator());
1623
1624 auto __ptr = __buckets_alloc_traits::allocate(__alloc, __bkt_count);
1625 __buckets_ptr __p = std::__to_address(__ptr);
1626 __builtin_memset(__p, 0, __bkt_count * sizeof(__node_base_ptr));
1627 return __p;
1628 }
1629
1630 template<typename _NodeAlloc>
1631 void
1632 _Hashtable_alloc<_NodeAlloc>::
1633 _M_deallocate_buckets(__buckets_ptr __bkts, size_t __bkt_count)
1634 {
1635 using _Ptr = typename __buckets_alloc_traits::pointer;
1636 auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
1637 __buckets_alloc_type __alloc(_M_node_allocator());
1638 __buckets_alloc_traits::deallocate(__alloc, __ptr, __bkt_count);
1639 }
1640
1641 ///@} hashtable-detail
1642} // namespace __detail
1643/// @endcond
1644_GLIBCXX_END_NAMESPACE_VERSION
1645} // namespace std
1646
1647#endif // _HASHTABLE_POLICY_H
tuple
functional_hash.h
stdexcept_throw.h
stl_algobase.h
stl_pair.h
aligned_buffer.h
std::operator*
constexpr complex< _Tp > operator*(const complex< _Tp > &__x, const complex< _Tp > &__y)
Return new complex value x times y.
Definition complex:434
std::true_type
__bool_constant< true > true_type
The type used as a compile-time boolean with true value.
Definition type_traits:119
std::false_type
__bool_constant< false > false_type
The type used as a compile-time boolean with false value.
Definition type_traits:122
std::pair::pair
pair(_T1, _T2) -> pair< _T1, _T2 >
Two pairs are equal iff their members are equal.
std::forward_as_tuple
constexpr tuple< _Elements &&... > forward_as_tuple(_Elements &&... __args) noexcept
Create a tuple of lvalue or rvalue references to the arguments.
Definition tuple:2705
std::addressof
constexpr _Tp * addressof(_Tp &__r) noexcept
Returns the actual address of the object or function referenced by r, even in the presence of an over...
Definition move.h:176
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition move.h:138
std::piecewise_construct
constexpr piecewise_construct_t piecewise_construct
Tag for piecewise construction of std::pair objects.
Definition stl_pair.h:82
std::forward
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition move.h:72
std::max
constexpr const _Tp & max(const _Tp &, const _Tp &)
This does what you think it does.
Definition stl_algobase.h:256
std::min
constexpr const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition stl_algobase.h:232
std
ISO C++ entities toplevel namespace is std.
std::distance
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
Definition stl_iterator_base_funcs.h:178
std::_Construct
constexpr void _Construct(_Tp *__p, _Args &&... __args)
Definition stl_construct.h:123
std::__detail
Implementation details not part of the namespace std interface.
__gnu_cxx::__int_traits
__numeric_traits_integer< _Tp > __int_traits
Convenience alias for __numeric_traits<integer-type>.
Definition ext/numeric_traits.h:134
__gnu_debug::__base
constexpr _Iterator __base(_Iterator __it)
Definition helper_functions.h:339
alloc_traits.h
numeric_traits.h