1// hashtable.h header -*- C++ -*-
2
3// Copyright (C) 2007-2017 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.h
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly. @headername{unordered_map, unordered_set}
28 */
29
30#ifndef _HASHTABLE_H
31#define _HASHTABLE_H 1
32
33#pragma GCC system_header
34
35#include <bits/hashtable_policy.h>
36#if __cplusplus > 201402L
37# include <bits/node_handle.h>
38#endif
39
40namespace std _GLIBCXX_VISIBILITY(default)
41{
42_GLIBCXX_BEGIN_NAMESPACE_VERSION
43
44 template<typename _Tp, typename _Hash>
45 using __cache_default
46 = __not_<__and_<// Do not cache for fast hasher.
47 __is_fast_hash<_Hash>,
48 // Mandatory to have erase not throwing.
49 __detail::__is_noexcept_hash<_Tp, _Hash>>>;
50
51 /**
52 * Primary class template _Hashtable.
53 *
54 * @ingroup hashtable-detail
55 *
56 * @tparam _Value CopyConstructible type.
57 *
58 * @tparam _Key CopyConstructible type.
59 *
60 * @tparam _Alloc An allocator type
61 * ([lib.allocator.requirements]) whose _Alloc::value_type is
62 * _Value. As a conforming extension, we allow for
63 * _Alloc::value_type != _Value.
64 *
65 * @tparam _ExtractKey Function object that takes an object of type
66 * _Value and returns a value of type _Key.
67 *
68 * @tparam _Equal Function object that takes two objects of type k
69 * and returns a bool-like value that is true if the two objects
70 * are considered equal.
71 *
72 * @tparam _H1 The hash function. A unary function object with
73 * argument type _Key and result type size_t. Return values should
74 * be distributed over the entire range [0, numeric_limits<size_t>:::max()].
75 *
76 * @tparam _H2 The range-hashing function (in the terminology of
77 * Tavori and Dreizin). A binary function object whose argument
78 * types and result type are all size_t. Given arguments r and N,
79 * the return value is in the range [0, N).
80 *
81 * @tparam _Hash The ranged hash function (Tavori and Dreizin). A
82 * binary function whose argument types are _Key and size_t and
83 * whose result type is size_t. Given arguments k and N, the
84 * return value is in the range [0, N). Default: hash(k, N) =
85 * h2(h1(k), N). If _Hash is anything other than the default, _H1
86 * and _H2 are ignored.
87 *
88 * @tparam _RehashPolicy Policy class with three members, all of
89 * which govern the bucket count. _M_next_bkt(n) returns a bucket
90 * count no smaller than n. _M_bkt_for_elements(n) returns a
91 * bucket count appropriate for an element count of n.
92 * _M_need_rehash(n_bkt, n_elt, n_ins) determines whether, if the
93 * current bucket count is n_bkt and the current element count is
94 * n_elt, we need to increase the bucket count. If so, returns
95 * make_pair(true, n), where n is the new bucket count. If not,
96 * returns make_pair(false, <anything>)
97 *
98 * @tparam _Traits Compile-time class with three boolean
99 * std::integral_constant members: __cache_hash_code, __constant_iterators,
100 * __unique_keys.
101 *
102 * Each _Hashtable data structure has:
103 *
104 * - _Bucket[] _M_buckets
105 * - _Hash_node_base _M_before_begin
106 * - size_type _M_bucket_count
107 * - size_type _M_element_count
108 *
109 * with _Bucket being _Hash_node* and _Hash_node containing:
110 *
111 * - _Hash_node* _M_next
112 * - Tp _M_value
113 * - size_t _M_hash_code if cache_hash_code is true
114 *
115 * In terms of Standard containers the hashtable is like the aggregation of:
116 *
117 * - std::forward_list<_Node> containing the elements
118 * - std::vector<std::forward_list<_Node>::iterator> representing the buckets
119 *
120 * The non-empty buckets contain the node before the first node in the
121 * bucket. This design makes it possible to implement something like a
122 * std::forward_list::insert_after on container insertion and
123 * std::forward_list::erase_after on container erase
124 * calls. _M_before_begin is equivalent to
125 * std::forward_list::before_begin. Empty buckets contain
126 * nullptr. Note that one of the non-empty buckets contains
127 * &_M_before_begin which is not a dereferenceable node so the
128 * node pointer in a bucket shall never be dereferenced, only its
129 * next node can be.
130 *
131 * Walking through a bucket's nodes requires a check on the hash code to
132 * see if each node is still in the bucket. Such a design assumes a
133 * quite efficient hash functor and is one of the reasons it is
134 * highly advisable to set __cache_hash_code to true.
135 *
136 * The container iterators are simply built from nodes. This way
137 * incrementing the iterator is perfectly efficient independent of
138 * how many empty buckets there are in the container.
139 *
140 * On insert we compute the element's hash code and use it to find the
141 * bucket index. If the element must be inserted in an empty bucket
142 * we add it at the beginning of the singly linked list and make the
143 * bucket point to _M_before_begin. The bucket that used to point to
144 * _M_before_begin, if any, is updated to point to its new before
145 * begin node.
146 *
147 * On erase, the simple iterator design requires using the hash
148 * functor to get the index of the bucket to update. For this
149 * reason, when __cache_hash_code is set to false the hash functor must
150 * not throw and this is enforced by a static assertion.
151 *
152 * Functionality is implemented by decomposition into base classes,
153 * where the derived _Hashtable class is used in _Map_base,
154 * _Insert, _Rehash_base, and _Equality base classes to access the
155 * "this" pointer. _Hashtable_base is used in the base classes as a
156 * non-recursive, fully-completed-type so that detailed nested type
157 * information, such as iterator type and node type, can be
158 * used. This is similar to the "Curiously Recurring Template
159 * Pattern" (CRTP) technique, but uses a reconstructed, not
160 * explicitly passed, template pattern.
161 *
162 * Base class templates are:
163 * - __detail::_Hashtable_base
164 * - __detail::_Map_base
165 * - __detail::_Insert
166 * - __detail::_Rehash_base
167 * - __detail::_Equality
168 */
169 template<typename _Key, typename _Value, typename _Alloc,
170 typename _ExtractKey, typename _Equal,
171 typename _H1, typename _H2, typename _Hash,
172 typename _RehashPolicy, typename _Traits>
173 class _Hashtable
174 : public __detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal,
175 _H1, _H2, _Hash, _Traits>,
176 public __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
177 _H1, _H2, _Hash, _RehashPolicy, _Traits>,
178 public __detail::_Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
179 _H1, _H2, _Hash, _RehashPolicy, _Traits>,
180 public __detail::_Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
181 _H1, _H2, _Hash, _RehashPolicy, _Traits>,
182 public __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
183 _H1, _H2, _Hash, _RehashPolicy, _Traits>,
184 private __detail::_Hashtable_alloc<
185 __alloc_rebind<_Alloc,
186 __detail::_Hash_node<_Value,
187 _Traits::__hash_cached::value>>>
188 {
189 using __traits_type = _Traits;
190 using __hash_cached = typename __traits_type::__hash_cached;
191 using __node_type = __detail::_Hash_node<_Value, __hash_cached::value>;
192 using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>;
193
194 using __hashtable_alloc = __detail::_Hashtable_alloc<__node_alloc_type>;
195
196 using __value_alloc_traits =
197 typename __hashtable_alloc::__value_alloc_traits;
198 using __node_alloc_traits =
199 typename __hashtable_alloc::__node_alloc_traits;
200 using __node_base = typename __hashtable_alloc::__node_base;
201 using __bucket_type = typename __hashtable_alloc::__bucket_type;
202
203 public:
204 typedef _Key key_type;
205 typedef _Value value_type;
206 typedef _Alloc allocator_type;
207 typedef _Equal key_equal;
208
209 // mapped_type, if present, comes from _Map_base.
210 // hasher, if present, comes from _Hash_code_base/_Hashtable_base.
211 typedef typename __value_alloc_traits::pointer pointer;
212 typedef typename __value_alloc_traits::const_pointer const_pointer;
213 typedef value_type& reference;
214 typedef const value_type& const_reference;
215
216 private:
217 using __rehash_type = _RehashPolicy;
218 using __rehash_state = typename __rehash_type::_State;
219
220 using __constant_iterators = typename __traits_type::__constant_iterators;
221 using __unique_keys = typename __traits_type::__unique_keys;
222
223 using __key_extract = typename std::conditional<
224 __constant_iterators::value,
225 __detail::_Identity,
226 __detail::_Select1st>::type;
227
228 using __hashtable_base = __detail::
229 _Hashtable_base<_Key, _Value, _ExtractKey,
230 _Equal, _H1, _H2, _Hash, _Traits>;
231
232 using __hash_code_base = typename __hashtable_base::__hash_code_base;
233 using __hash_code = typename __hashtable_base::__hash_code;
234 using __ireturn_type = typename __hashtable_base::__ireturn_type;
235
236 using __map_base = __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey,
237 _Equal, _H1, _H2, _Hash,
238 _RehashPolicy, _Traits>;
239
240 using __rehash_base = __detail::_Rehash_base<_Key, _Value, _Alloc,
241 _ExtractKey, _Equal,
242 _H1, _H2, _Hash,
243 _RehashPolicy, _Traits>;
244
245 using __eq_base = __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey,
246 _Equal, _H1, _H2, _Hash,
247 _RehashPolicy, _Traits>;
248
249 using __reuse_or_alloc_node_type =
250 __detail::_ReuseOrAllocNode<__node_alloc_type>;
251
252 // Metaprogramming for picking apart hash caching.
253 template<typename _Cond>
254 using __if_hash_cached = __or_<__not_<__hash_cached>, _Cond>;
255
256 template<typename _Cond>
257 using __if_hash_not_cached = __or_<__hash_cached, _Cond>;
258
259 // Compile-time diagnostics.
260
261 // _Hash_code_base has everything protected, so use this derived type to
262 // access it.
263 struct __hash_code_base_access : __hash_code_base
264 { using __hash_code_base::_M_bucket_index; };
265
266 // Getting a bucket index from a node shall not throw because it is used
267 // in methods (erase, swap...) that shall not throw.
268 static_assert(noexcept(declval<const __hash_code_base_access&>()
269 ._M_bucket_index((const __node_type*)nullptr,
270 (std::size_t)0)),
271 "Cache the hash code or qualify your functors involved"
272 " in hash code and bucket index computation with noexcept");
273
274 // Following two static assertions are necessary to guarantee
275 // that local_iterator will be default constructible.
276
277 // When hash codes are cached local iterator inherits from H2 functor
278 // which must then be default constructible.
279 static_assert(__if_hash_cached<is_default_constructible<_H2>>::value,
280 "Functor used to map hash code to bucket index"
281 " must be default constructible");
282
283 template<typename _Keya, typename _Valuea, typename _Alloca,
284 typename _ExtractKeya, typename _Equala,
285 typename _H1a, typename _H2a, typename _Hasha,
286 typename _RehashPolicya, typename _Traitsa,
287 bool _Unique_keysa>
288 friend struct __detail::_Map_base;
289
290 template<typename _Keya, typename _Valuea, typename _Alloca,
291 typename _ExtractKeya, typename _Equala,
292 typename _H1a, typename _H2a, typename _Hasha,
293 typename _RehashPolicya, typename _Traitsa>
294 friend struct __detail::_Insert_base;
295
296 template<typename _Keya, typename _Valuea, typename _Alloca,
297 typename _ExtractKeya, typename _Equala,
298 typename _H1a, typename _H2a, typename _Hasha,
299 typename _RehashPolicya, typename _Traitsa,
300 bool _Constant_iteratorsa>
301 friend struct __detail::_Insert;
302
303 public:
304 using size_type = typename __hashtable_base::size_type;
305 using difference_type = typename __hashtable_base::difference_type;
306
307 using iterator = typename __hashtable_base::iterator;
308 using const_iterator = typename __hashtable_base::const_iterator;
309
310 using local_iterator = typename __hashtable_base::local_iterator;
311 using const_local_iterator = typename __hashtable_base::
312 const_local_iterator;
313
314#if __cplusplus > 201402L
315 using node_type = _Node_handle<_Key, _Value, __node_alloc_type>;
316 using insert_return_type = _Node_insert_return<iterator, node_type>;
317#endif
318
319 private:
320 __bucket_type* _M_buckets = &_M_single_bucket;
321 size_type _M_bucket_count = 1;
322 __node_base _M_before_begin;
323 size_type _M_element_count = 0;
324 _RehashPolicy _M_rehash_policy;
325
326 // A single bucket used when only need for 1 bucket. Especially
327 // interesting in move semantic to leave hashtable with only 1 buckets
328 // which is not allocated so that we can have those operations noexcept
329 // qualified.
330 // Note that we can't leave hashtable with 0 bucket without adding
331 // numerous checks in the code to avoid 0 modulus.
332 __bucket_type _M_single_bucket = nullptr;
333
334 bool
335 _M_uses_single_bucket(__bucket_type* __bkts) const
336 { return __builtin_expect(__bkts == &_M_single_bucket, false); }
337
338 bool
339 _M_uses_single_bucket() const
340 { return _M_uses_single_bucket(_M_buckets); }
341
342 __hashtable_alloc&
343 _M_base_alloc() { return *this; }
344
345 __bucket_type*
346 _M_allocate_buckets(size_type __n)
347 {
348 if (__builtin_expect(__n == 1, false))
349 {
350 _M_single_bucket = nullptr;
351 return &_M_single_bucket;
352 }
353
354 return __hashtable_alloc::_M_allocate_buckets(__n);
355 }
356
357 void
358 _M_deallocate_buckets(__bucket_type* __bkts, size_type __n)
359 {
360 if (_M_uses_single_bucket(__bkts))
361 return;
362
363 __hashtable_alloc::_M_deallocate_buckets(__bkts, __n);
364 }
365
366 void
367 _M_deallocate_buckets()
368 { _M_deallocate_buckets(_M_buckets, _M_bucket_count); }
369
370 // Gets bucket begin, deals with the fact that non-empty buckets contain
371 // their before begin node.
372 __node_type*
373 _M_bucket_begin(size_type __bkt) const;
374
375 __node_type*
376 _M_begin() const
377 { return static_cast<__node_type*>(_M_before_begin._M_nxt); }
378
379 template<typename _NodeGenerator>
380 void
381 _M_assign(const _Hashtable&, const _NodeGenerator&);
382
383 void
384 _M_move_assign(_Hashtable&&, std::true_type);
385
386 void
387 _M_move_assign(_Hashtable&&, std::false_type);
388
389 void
390 _M_reset() noexcept;
391
392 _Hashtable(const _H1& __h1, const _H2& __h2, const _Hash& __h,
393 const _Equal& __eq, const _ExtractKey& __exk,
394 const allocator_type& __a)
395 : __hashtable_base(__exk, __h1, __h2, __h, __eq),
396 __hashtable_alloc(__node_alloc_type(__a))
397 { }
398
399 public:
400 // Constructor, destructor, assignment, swap
401 _Hashtable() = default;
402 _Hashtable(size_type __bucket_hint,
403 const _H1&, const _H2&, const _Hash&,
404 const _Equal&, const _ExtractKey&,
405 const allocator_type&);
406
407 template<typename _InputIterator>
408 _Hashtable(_InputIterator __first, _InputIterator __last,
409 size_type __bucket_hint,
410 const _H1&, const _H2&, const _Hash&,
411 const _Equal&, const _ExtractKey&,
412 const allocator_type&);
413
414 _Hashtable(const _Hashtable&);
415
416 _Hashtable(_Hashtable&&) noexcept;
417
418 _Hashtable(const _Hashtable&, const allocator_type&);
419
420 _Hashtable(_Hashtable&&, const allocator_type&);
421
422 // Use delegating constructors.
423 explicit
424 _Hashtable(const allocator_type& __a)
425 : __hashtable_alloc(__node_alloc_type(__a))
426 { }
427
428 explicit
429 _Hashtable(size_type __n,
430 const _H1& __hf = _H1(),
431 const key_equal& __eql = key_equal(),
432 const allocator_type& __a = allocator_type())
433 : _Hashtable(__n, __hf, _H2(), _Hash(), __eql,
434 __key_extract(), __a)
435 { }
436
437 template<typename _InputIterator>
438 _Hashtable(_InputIterator __f, _InputIterator __l,
439 size_type __n = 0,
440 const _H1& __hf = _H1(),
441 const key_equal& __eql = key_equal(),
442 const allocator_type& __a = allocator_type())
443 : _Hashtable(__f, __l, __n, __hf, _H2(), _Hash(), __eql,
444 __key_extract(), __a)
445 { }
446
447 _Hashtable(initializer_list<value_type> __l,
448 size_type __n = 0,
449 const _H1& __hf = _H1(),
450 const key_equal& __eql = key_equal(),
451 const allocator_type& __a = allocator_type())
452 : _Hashtable(__l.begin(), __l.end(), __n, __hf, _H2(), _Hash(), __eql,
453 __key_extract(), __a)
454 { }
455
456 _Hashtable&
457 operator=(const _Hashtable& __ht);
458
459 _Hashtable&
460 operator=(_Hashtable&& __ht)
461 noexcept(__node_alloc_traits::_S_nothrow_move()
462 && is_nothrow_move_assignable<_H1>::value
463 && is_nothrow_move_assignable<_Equal>::value)
464 {
465 constexpr bool __move_storage =
466 __node_alloc_traits::_S_propagate_on_move_assign()
467 || __node_alloc_traits::_S_always_equal();
468 _M_move_assign(std::move(__ht), __bool_constant<__move_storage>());
469 return *this;
470 }
471
472 _Hashtable&
473 operator=(initializer_list<value_type> __l)
474 {
475 __reuse_or_alloc_node_type __roan(_M_begin(), *this);
476 _M_before_begin._M_nxt = nullptr;
477 clear();
478 this->_M_insert_range(__l.begin(), __l.end(), __roan);
479 return *this;
480 }
481
482 ~_Hashtable() noexcept;
483
484 void
485 swap(_Hashtable&)
486 noexcept(__and_<__is_nothrow_swappable<_H1>,
487 __is_nothrow_swappable<_Equal>>::value);
488
489 // Basic container operations
490 iterator
491 begin() noexcept
492 { return iterator(_M_begin()); }
493
494 const_iterator
495 begin() const noexcept
496 { return const_iterator(_M_begin()); }
497
498 iterator
499 end() noexcept
500 { return iterator(nullptr); }
501
502 const_iterator
503 end() const noexcept
504 { return const_iterator(nullptr); }
505
506 const_iterator
507 cbegin() const noexcept
508 { return const_iterator(_M_begin()); }
509
510 const_iterator
511 cend() const noexcept
512 { return const_iterator(nullptr); }
513
514 size_type
515 size() const noexcept
516 { return _M_element_count; }
517
518 bool
519 empty() const noexcept
520 { return size() == 0; }
521
522 allocator_type
523 get_allocator() const noexcept
524 { return allocator_type(this->_M_node_allocator()); }
525
526 size_type
527 max_size() const noexcept
528 { return __node_alloc_traits::max_size(this->_M_node_allocator()); }
529
530 // Observers
531 key_equal
532 key_eq() const
533 { return this->_M_eq(); }
534
535 // hash_function, if present, comes from _Hash_code_base.
536
537 // Bucket operations
538 size_type
539 bucket_count() const noexcept
540 { return _M_bucket_count; }
541
542 size_type
543 max_bucket_count() const noexcept
544 { return max_size(); }
545
546 size_type
547 bucket_size(size_type __n) const
548 { return std::distance(begin(__n), end(__n)); }
549
550 size_type
551 bucket(const key_type& __k) const
552 { return _M_bucket_index(__k, this->_M_hash_code(__k)); }
553
554 local_iterator
555 begin(size_type __n)
556 {
557 return local_iterator(*this, _M_bucket_begin(__n),
558 __n, _M_bucket_count);
559 }
560
561 local_iterator
562 end(size_type __n)
563 { return local_iterator(*this, nullptr, __n, _M_bucket_count); }
564
565 const_local_iterator
566 begin(size_type __n) const
567 {
568 return const_local_iterator(*this, _M_bucket_begin(__n),
569 __n, _M_bucket_count);
570 }
571
572 const_local_iterator
573 end(size_type __n) const
574 { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
575
576 // DR 691.
577 const_local_iterator
578 cbegin(size_type __n) const
579 {
580 return const_local_iterator(*this, _M_bucket_begin(__n),
581 __n, _M_bucket_count);
582 }
583
584 const_local_iterator
585 cend(size_type __n) const
586 { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
587
588 float
589 load_factor() const noexcept
590 {
591 return static_cast<float>(size()) / static_cast<float>(bucket_count());
592 }
593
594 // max_load_factor, if present, comes from _Rehash_base.
595
596 // Generalization of max_load_factor. Extension, not found in
597 // TR1. Only useful if _RehashPolicy is something other than
598 // the default.
599 const _RehashPolicy&
600 __rehash_policy() const
601 { return _M_rehash_policy; }
602
603 void
604 __rehash_policy(const _RehashPolicy& __pol)
605 { _M_rehash_policy = __pol; }
606
607 // Lookup.
608 iterator
609 find(const key_type& __k);
610
611 const_iterator
612 find(const key_type& __k) const;
613
614 size_type
615 count(const key_type& __k) const;
616
617 std::pair<iterator, iterator>
618 equal_range(const key_type& __k);
619
620 std::pair<const_iterator, const_iterator>
621 equal_range(const key_type& __k) const;
622
623 protected:
624 // Bucket index computation helpers.
625 size_type
626 _M_bucket_index(__node_type* __n) const noexcept
627 { return __hash_code_base::_M_bucket_index(__n, _M_bucket_count); }
628
629 size_type
630 _M_bucket_index(const key_type& __k, __hash_code __c) const
631 { return __hash_code_base::_M_bucket_index(__k, __c, _M_bucket_count); }
632
633 // Find and insert helper functions and types
634 // Find the node before the one matching the criteria.
635 __node_base*
636 _M_find_before_node(size_type, const key_type&, __hash_code) const;
637
638 __node_type*
639 _M_find_node(size_type __bkt, const key_type& __key,
640 __hash_code __c) const
641 {
642 __node_base* __before_n = _M_find_before_node(__bkt, __key, __c);
643 if (__before_n)
644 return static_cast<__node_type*>(__before_n->_M_nxt);
645 return nullptr;
646 }
647
648 // Insert a node at the beginning of a bucket.
649 void
650 _M_insert_bucket_begin(size_type, __node_type*);
651
652 // Remove the bucket first node
653 void
654 _M_remove_bucket_begin(size_type __bkt, __node_type* __next_n,
655 size_type __next_bkt);
656
657 // Get the node before __n in the bucket __bkt
658 __node_base*
659 _M_get_previous_node(size_type __bkt, __node_base* __n);
660
661 // Insert node with hash code __code, in bucket bkt if no rehash (assumes
662 // no element with its key already present). Take ownership of the node,
663 // deallocate it on exception.
664 iterator
665 _M_insert_unique_node(size_type __bkt, __hash_code __code,
666 __node_type* __n);
667
668 // Insert node with hash code __code. Take ownership of the node,
669 // deallocate it on exception.
670 iterator
671 _M_insert_multi_node(__node_type* __hint,
672 __hash_code __code, __node_type* __n);
673
674 template<typename... _Args>
675 std::pair<iterator, bool>
676 _M_emplace(std::true_type, _Args&&... __args);
677
678 template<typename... _Args>
679 iterator
680 _M_emplace(std::false_type __uk, _Args&&... __args)
681 { return _M_emplace(cend(), __uk, std::forward<_Args>(__args)...); }
682
683 // Emplace with hint, useless when keys are unique.
684 template<typename... _Args>
685 iterator
686 _M_emplace(const_iterator, std::true_type __uk, _Args&&... __args)
687 { return _M_emplace(__uk, std::forward<_Args>(__args)...).first; }
688
689 template<typename... _Args>
690 iterator
691 _M_emplace(const_iterator, std::false_type, _Args&&... __args);
692
693 template<typename _Arg, typename _NodeGenerator>
694 std::pair<iterator, bool>
695 _M_insert(_Arg&&, const _NodeGenerator&, std::true_type);
696
697 template<typename _Arg, typename _NodeGenerator>
698 iterator
699 _M_insert(_Arg&& __arg, const _NodeGenerator& __node_gen,
700 std::false_type __uk)
701 {
702 return _M_insert(cend(), std::forward<_Arg>(__arg), __node_gen,
703 __uk);
704 }
705
706 // Insert with hint, not used when keys are unique.
707 template<typename _Arg, typename _NodeGenerator>
708 iterator
709 _M_insert(const_iterator, _Arg&& __arg,
710 const _NodeGenerator& __node_gen, std::true_type __uk)
711 {
712 return
713 _M_insert(std::forward<_Arg>(__arg), __node_gen, __uk).first;
714 }
715
716 // Insert with hint when keys are not unique.
717 template<typename _Arg, typename _NodeGenerator>
718 iterator
719 _M_insert(const_iterator, _Arg&&,
720 const _NodeGenerator&, std::false_type);
721
722 size_type
723 _M_erase(std::true_type, const key_type&);
724
725 size_type
726 _M_erase(std::false_type, const key_type&);
727
728 iterator
729 _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n);
730
731 public:
732 // Emplace
733 template<typename... _Args>
734 __ireturn_type
735 emplace(_Args&&... __args)
736 { return _M_emplace(__unique_keys(), std::forward<_Args>(__args)...); }
737
738 template<typename... _Args>
739 iterator
740 emplace_hint(const_iterator __hint, _Args&&... __args)
741 {
742 return _M_emplace(__hint, __unique_keys(),
743 std::forward<_Args>(__args)...);
744 }
745
746 // Insert member functions via inheritance.
747
748 // Erase
749 iterator
750 erase(const_iterator);
751
752 // LWG 2059.
753 iterator
754 erase(iterator __it)
755 { return erase(const_iterator(__it)); }
756
757 size_type
758 erase(const key_type& __k)
759 { return _M_erase(__unique_keys(), __k); }
760
761 iterator
762 erase(const_iterator, const_iterator);
763
764 void
765 clear() noexcept;
766
767 // Set number of buckets to be appropriate for container of n element.
768 void rehash(size_type __n);
769
770 // DR 1189.
771 // reserve, if present, comes from _Rehash_base.
772
773#if __cplusplus > 201402L
774 /// Re-insert an extracted node into a container with unique keys.
775 insert_return_type
776 _M_reinsert_node(node_type&& __nh)
777 {
778 insert_return_type __ret;
779 if (__nh.empty())
780 __ret.position = end();
781 else
782 {
783 __glibcxx_assert(get_allocator() == __nh.get_allocator());
784
785 const key_type& __k = __nh._M_key();
786 __hash_code __code = this->_M_hash_code(__k);
787 size_type __bkt = _M_bucket_index(__k, __code);
788 if (__node_type* __n = _M_find_node(__bkt, __k, __code))
789 {
790 __ret.node = std::move(__nh);
791 __ret.position = iterator(__n);
792 __ret.inserted = false;
793 }
794 else
795 {
796 __ret.position
797 = _M_insert_unique_node(__bkt, __code, __nh._M_ptr);
798 __nh._M_ptr = nullptr;
799 __ret.inserted = true;
800 }
801 }
802 return __ret;
803 }
804
805 /// Re-insert an extracted node into a container with equivalent keys.
806 iterator
807 _M_reinsert_node_multi(const_iterator __hint, node_type&& __nh)
808 {
809 iterator __ret;
810 if (__nh.empty())
811 __ret = end();
812 else
813 {
814 __glibcxx_assert(get_allocator() == __nh.get_allocator());
815
816 auto __code = this->_M_hash_code(__nh._M_key());
817 auto __node = std::exchange(__nh._M_ptr, nullptr);
818 // FIXME: this deallocates the node on exception.
819 __ret = _M_insert_multi_node(__hint._M_cur, __code, __node);
820 }
821 return __ret;
822 }
823
824 /// Extract a node.
825 node_type
826 extract(const_iterator __pos)
827 {
828 __node_type* __n = __pos._M_cur;
829 size_t __bkt = _M_bucket_index(__n);
830
831 // Look for previous node to unlink it from the erased one, this
832 // is why we need buckets to contain the before begin to make
833 // this search fast.
834 __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
835
836 if (__prev_n == _M_buckets[__bkt])
837 _M_remove_bucket_begin(__bkt, __n->_M_next(),
838 __n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
839 else if (__n->_M_nxt)
840 {
841 size_type __next_bkt = _M_bucket_index(__n->_M_next());
842 if (__next_bkt != __bkt)
843 _M_buckets[__next_bkt] = __prev_n;
844 }
845
846 __prev_n->_M_nxt = __n->_M_nxt;
847 __n->_M_nxt = nullptr;
848 --_M_element_count;
849 return { __n, this->_M_node_allocator() };
850 }
851
852 /// Extract a node.
853 node_type
854 extract(const _Key& __k)
855 {
856 node_type __nh;
857 auto __pos = find(__k);
858 if (__pos != end())
859 __nh = extract(const_iterator(__pos));
860 return __nh;
861 }
862
863 /// Merge from a compatible container into one with unique keys.
864 template<typename _Compatible_Hashtable>
865 void
866 _M_merge_unique(_Compatible_Hashtable& __src) noexcept
867 {
868 static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
869 node_type>, "Node types are compatible");
870 __glibcxx_assert(get_allocator() == __src.get_allocator());
871
872 for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
873 {
874 auto __pos = __i++;
875 const key_type& __k = this->_M_extract()(__pos._M_cur->_M_v());
876 __hash_code __code = this->_M_hash_code(__k);
877 size_type __bkt = _M_bucket_index(__k, __code);
878 if (_M_find_node(__bkt, __k, __code) == nullptr)
879 {
880 auto __nh = __src.extract(__pos);
881 _M_insert_unique_node(__bkt, __code, __nh._M_ptr);
882 __nh._M_ptr = nullptr;
883 }
884 }
885 }
886
887 /// Merge from a compatible container into one with equivalent keys.
888 template<typename _Compatible_Hashtable>
889 void
890 _M_merge_multi(_Compatible_Hashtable& __src) noexcept
891 {
892 static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
893 node_type>, "Node types are compatible");
894 __glibcxx_assert(get_allocator() == __src.get_allocator());
895
896 this->reserve(size() + __src.size());
897 for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
898 _M_reinsert_node_multi(cend(), __src.extract(__i++));
899 }
900#endif // C++17
901
902 private:
903 // Helper rehash method used when keys are unique.
904 void _M_rehash_aux(size_type __n, std::true_type);
905
906 // Helper rehash method used when keys can be non-unique.
907 void _M_rehash_aux(size_type __n, std::false_type);
908
909 // Unconditionally change size of bucket array to n, restore
910 // hash policy state to __state on exception.
911 void _M_rehash(size_type __n, const __rehash_state& __state);
912 };
913
914
915 // Definitions of class template _Hashtable's out-of-line member functions.
916 template<typename _Key, typename _Value,
917 typename _Alloc, typename _ExtractKey, typename _Equal,
918 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
919 typename _Traits>
920 auto
921 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
922 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
923 _M_bucket_begin(size_type __bkt) const
924 -> __node_type*
925 {
926 __node_base* __n = _M_buckets[__bkt];
927 return __n ? static_cast<__node_type*>(__n->_M_nxt) : nullptr;
928 }
929
930 template<typename _Key, typename _Value,
931 typename _Alloc, typename _ExtractKey, typename _Equal,
932 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
933 typename _Traits>
934 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
935 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
936 _Hashtable(size_type __bucket_hint,
937 const _H1& __h1, const _H2& __h2, const _Hash& __h,
938 const _Equal& __eq, const _ExtractKey& __exk,
939 const allocator_type& __a)
940 : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
941 {
942 auto __bkt = _M_rehash_policy._M_next_bkt(__bucket_hint);
943 if (__bkt > _M_bucket_count)
944 {
945 _M_buckets = _M_allocate_buckets(__bkt);
946 _M_bucket_count = __bkt;
947 }
948 }
949
950 template<typename _Key, typename _Value,
951 typename _Alloc, typename _ExtractKey, typename _Equal,
952 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
953 typename _Traits>
954 template<typename _InputIterator>
955 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
956 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
957 _Hashtable(_InputIterator __f, _InputIterator __l,
958 size_type __bucket_hint,
959 const _H1& __h1, const _H2& __h2, const _Hash& __h,
960 const _Equal& __eq, const _ExtractKey& __exk,
961 const allocator_type& __a)
962 : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
963 {
964 auto __nb_elems = __detail::__distance_fw(__f, __l);
965 auto __bkt_count =
966 _M_rehash_policy._M_next_bkt(
967 std::max(_M_rehash_policy._M_bkt_for_elements(__nb_elems),
968 __bucket_hint));
969
970 if (__bkt_count > _M_bucket_count)
971 {
972 _M_buckets = _M_allocate_buckets(__bkt_count);
973 _M_bucket_count = __bkt_count;
974 }
975
976 for (; __f != __l; ++__f)
977 this->insert(*__f);
978 }
979
980 template<typename _Key, typename _Value,
981 typename _Alloc, typename _ExtractKey, typename _Equal,
982 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
983 typename _Traits>
984 auto
985 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
986 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
987 operator=(const _Hashtable& __ht)
988 -> _Hashtable&
989 {
990 if (&__ht == this)
991 return *this;
992
993 if (__node_alloc_traits::_S_propagate_on_copy_assign())
994 {
995 auto& __this_alloc = this->_M_node_allocator();
996 auto& __that_alloc = __ht._M_node_allocator();
997 if (!__node_alloc_traits::_S_always_equal()
998 && __this_alloc != __that_alloc)
999 {
1000 // Replacement allocator cannot free existing storage.
1001 this->_M_deallocate_nodes(_M_begin());
1002 _M_before_begin._M_nxt = nullptr;
1003 _M_deallocate_buckets();
1004 _M_buckets = nullptr;
1005 std::__alloc_on_copy(__this_alloc, __that_alloc);
1006 __hashtable_base::operator=(__ht);
1007 _M_bucket_count = __ht._M_bucket_count;
1008 _M_element_count = __ht._M_element_count;
1009 _M_rehash_policy = __ht._M_rehash_policy;
1010 __try
1011 {
1012 _M_assign(__ht,
1013 [this](const __node_type* __n)
1014 { return this->_M_allocate_node(__n->_M_v()); });
1015 }
1016 __catch(...)
1017 {
1018 // _M_assign took care of deallocating all memory. Now we
1019 // must make sure this instance remains in a usable state.
1020 _M_reset();
1021 __throw_exception_again;
1022 }
1023 return *this;
1024 }
1025 std::__alloc_on_copy(__this_alloc, __that_alloc);
1026 }
1027
1028 // Reuse allocated buckets and nodes.
1029 __bucket_type* __former_buckets = nullptr;
1030 std::size_t __former_bucket_count = _M_bucket_count;
1031 const __rehash_state& __former_state = _M_rehash_policy._M_state();
1032
1033 if (_M_bucket_count != __ht._M_bucket_count)
1034 {
1035 __former_buckets = _M_buckets;
1036 _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
1037 _M_bucket_count = __ht._M_bucket_count;
1038 }
1039 else
1040 __builtin_memset(_M_buckets, 0,
1041 _M_bucket_count * sizeof(__bucket_type));
1042
1043 __try
1044 {
1045 __hashtable_base::operator=(__ht);
1046 _M_element_count = __ht._M_element_count;
1047 _M_rehash_policy = __ht._M_rehash_policy;
1048 __reuse_or_alloc_node_type __roan(_M_begin(), *this);
1049 _M_before_begin._M_nxt = nullptr;
1050 _M_assign(__ht,
1051 [&__roan](const __node_type* __n)
1052 { return __roan(__n->_M_v()); });
1053 if (__former_buckets)
1054 _M_deallocate_buckets(__former_buckets, __former_bucket_count);
1055 }
1056 __catch(...)
1057 {
1058 if (__former_buckets)
1059 {
1060 // Restore previous buckets.
1061 _M_deallocate_buckets();
1062 _M_rehash_policy._M_reset(__former_state);
1063 _M_buckets = __former_buckets;
1064 _M_bucket_count = __former_bucket_count;
1065 }
1066 __builtin_memset(_M_buckets, 0,
1067 _M_bucket_count * sizeof(__bucket_type));
1068 __throw_exception_again;
1069 }
1070 return *this;
1071 }
1072
1073 template<typename _Key, typename _Value,
1074 typename _Alloc, typename _ExtractKey, typename _Equal,
1075 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1076 typename _Traits>
1077 template<typename _NodeGenerator>
1078 void
1079 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1080 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1081 _M_assign(const _Hashtable& __ht, const _NodeGenerator& __node_gen)
1082 {
1083 __bucket_type* __buckets = nullptr;
1084 if (!_M_buckets)
1085 _M_buckets = __buckets = _M_allocate_buckets(_M_bucket_count);
1086
1087 __try
1088 {
1089 if (!__ht._M_before_begin._M_nxt)
1090 return;
1091
1092 // First deal with the special first node pointed to by
1093 // _M_before_begin.
1094 __node_type* __ht_n = __ht._M_begin();
1095 __node_type* __this_n = __node_gen(__ht_n);
1096 this->_M_copy_code(__this_n, __ht_n);
1097 _M_before_begin._M_nxt = __this_n;
1098 _M_buckets[_M_bucket_index(__this_n)] = &_M_before_begin;
1099
1100 // Then deal with other nodes.
1101 __node_base* __prev_n = __this_n;
1102 for (__ht_n = __ht_n->_M_next(); __ht_n; __ht_n = __ht_n->_M_next())
1103 {
1104 __this_n = __node_gen(__ht_n);
1105 __prev_n->_M_nxt = __this_n;
1106 this->_M_copy_code(__this_n, __ht_n);
1107 size_type __bkt = _M_bucket_index(__this_n);
1108 if (!_M_buckets[__bkt])
1109 _M_buckets[__bkt] = __prev_n;
1110 __prev_n = __this_n;
1111 }
1112 }
1113 __catch(...)
1114 {
1115 clear();
1116 if (__buckets)
1117 _M_deallocate_buckets();
1118 __throw_exception_again;
1119 }
1120 }
1121
1122 template<typename _Key, typename _Value,
1123 typename _Alloc, typename _ExtractKey, typename _Equal,
1124 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1125 typename _Traits>
1126 void
1127 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1128 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1129 _M_reset() noexcept
1130 {
1131 _M_rehash_policy._M_reset();
1132 _M_bucket_count = 1;
1133 _M_single_bucket = nullptr;
1134 _M_buckets = &_M_single_bucket;
1135 _M_before_begin._M_nxt = nullptr;
1136 _M_element_count = 0;
1137 }
1138
1139 template<typename _Key, typename _Value,
1140 typename _Alloc, typename _ExtractKey, typename _Equal,
1141 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1142 typename _Traits>
1143 void
1144 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1145 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1146 _M_move_assign(_Hashtable&& __ht, std::true_type)
1147 {
1148 this->_M_deallocate_nodes(_M_begin());
1149 _M_deallocate_buckets();
1150 __hashtable_base::operator=(std::move(__ht));
1151 _M_rehash_policy = __ht._M_rehash_policy;
1152 if (!__ht._M_uses_single_bucket())
1153 _M_buckets = __ht._M_buckets;
1154 else
1155 {
1156 _M_buckets = &_M_single_bucket;
1157 _M_single_bucket = __ht._M_single_bucket;
1158 }
1159 _M_bucket_count = __ht._M_bucket_count;
1160 _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
1161 _M_element_count = __ht._M_element_count;
1162 std::__alloc_on_move(this->_M_node_allocator(), __ht._M_node_allocator());
1163
1164 // Fix buckets containing the _M_before_begin pointers that can't be
1165 // moved.
1166 if (_M_begin())
1167 _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1168 __ht._M_reset();
1169 }
1170
1171 template<typename _Key, typename _Value,
1172 typename _Alloc, typename _ExtractKey, typename _Equal,
1173 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1174 typename _Traits>
1175 void
1176 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1177 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1178 _M_move_assign(_Hashtable&& __ht, std::false_type)
1179 {
1180 if (__ht._M_node_allocator() == this->_M_node_allocator())
1181 _M_move_assign(std::move(__ht), std::true_type());
1182 else
1183 {
1184 // Can't move memory, move elements then.
1185 __bucket_type* __former_buckets = nullptr;
1186 size_type __former_bucket_count = _M_bucket_count;
1187 const __rehash_state& __former_state = _M_rehash_policy._M_state();
1188
1189 if (_M_bucket_count != __ht._M_bucket_count)
1190 {
1191 __former_buckets = _M_buckets;
1192 _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
1193 _M_bucket_count = __ht._M_bucket_count;
1194 }
1195 else
1196 __builtin_memset(_M_buckets, 0,
1197 _M_bucket_count * sizeof(__bucket_type));
1198
1199 __try
1200 {
1201 __hashtable_base::operator=(std::move(__ht));
1202 _M_element_count = __ht._M_element_count;
1203 _M_rehash_policy = __ht._M_rehash_policy;
1204 __reuse_or_alloc_node_type __roan(_M_begin(), *this);
1205 _M_before_begin._M_nxt = nullptr;
1206 _M_assign(__ht,
1207 [&__roan](__node_type* __n)
1208 { return __roan(std::move_if_noexcept(__n->_M_v())); });
1209
1210 if (__former_buckets)
1211 _M_deallocate_buckets(__former_buckets, __former_bucket_count);
1212 __ht.clear();
1213 }
1214 __catch(...)
1215 {
1216 if (__former_buckets)
1217 {
1218 _M_deallocate_buckets();
1219 _M_rehash_policy._M_reset(__former_state);
1220 _M_buckets = __former_buckets;
1221 _M_bucket_count = __former_bucket_count;
1222 }
1223 __builtin_memset(_M_buckets, 0,
1224 _M_bucket_count * sizeof(__bucket_type));
1225 __throw_exception_again;
1226 }
1227 }
1228 }
1229
1230 template<typename _Key, typename _Value,
1231 typename _Alloc, typename _ExtractKey, typename _Equal,
1232 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1233 typename _Traits>
1234 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1235 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1236 _Hashtable(const _Hashtable& __ht)
1237 : __hashtable_base(__ht),
1238 __map_base(__ht),
1239 __rehash_base(__ht),
1240 __hashtable_alloc(
1241 __node_alloc_traits::_S_select_on_copy(__ht._M_node_allocator())),
1242 _M_buckets(nullptr),
1243 _M_bucket_count(__ht._M_bucket_count),
1244 _M_element_count(__ht._M_element_count),
1245 _M_rehash_policy(__ht._M_rehash_policy)
1246 {
1247 _M_assign(__ht,
1248 [this](const __node_type* __n)
1249 { return this->_M_allocate_node(__n->_M_v()); });
1250 }
1251
1252 template<typename _Key, typename _Value,
1253 typename _Alloc, typename _ExtractKey, typename _Equal,
1254 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1255 typename _Traits>
1256 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1257 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1258 _Hashtable(_Hashtable&& __ht) noexcept
1259 : __hashtable_base(__ht),
1260 __map_base(__ht),
1261 __rehash_base(__ht),
1262 __hashtable_alloc(std::move(__ht._M_base_alloc())),
1263 _M_buckets(__ht._M_buckets),
1264 _M_bucket_count(__ht._M_bucket_count),
1265 _M_before_begin(__ht._M_before_begin._M_nxt),
1266 _M_element_count(__ht._M_element_count),
1267 _M_rehash_policy(__ht._M_rehash_policy)
1268 {
1269 // Update, if necessary, buckets if __ht is using its single bucket.
1270 if (__ht._M_uses_single_bucket())
1271 {
1272 _M_buckets = &_M_single_bucket;
1273 _M_single_bucket = __ht._M_single_bucket;
1274 }
1275
1276 // Update, if necessary, bucket pointing to before begin that hasn't
1277 // moved.
1278 if (_M_begin())
1279 _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1280
1281 __ht._M_reset();
1282 }
1283
1284 template<typename _Key, typename _Value,
1285 typename _Alloc, typename _ExtractKey, typename _Equal,
1286 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1287 typename _Traits>
1288 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1289 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1290 _Hashtable(const _Hashtable& __ht, const allocator_type& __a)
1291 : __hashtable_base(__ht),
1292 __map_base(__ht),
1293 __rehash_base(__ht),
1294 __hashtable_alloc(__node_alloc_type(__a)),
1295 _M_buckets(),
1296 _M_bucket_count(__ht._M_bucket_count),
1297 _M_element_count(__ht._M_element_count),
1298 _M_rehash_policy(__ht._M_rehash_policy)
1299 {
1300 _M_assign(__ht,
1301 [this](const __node_type* __n)
1302 { return this->_M_allocate_node(__n->_M_v()); });
1303 }
1304
1305 template<typename _Key, typename _Value,
1306 typename _Alloc, typename _ExtractKey, typename _Equal,
1307 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1308 typename _Traits>
1309 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1310 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1311 _Hashtable(_Hashtable&& __ht, const allocator_type& __a)
1312 : __hashtable_base(__ht),
1313 __map_base(__ht),
1314 __rehash_base(__ht),
1315 __hashtable_alloc(__node_alloc_type(__a)),
1316 _M_buckets(nullptr),
1317 _M_bucket_count(__ht._M_bucket_count),
1318 _M_element_count(__ht._M_element_count),
1319 _M_rehash_policy(__ht._M_rehash_policy)
1320 {
1321 if (__ht._M_node_allocator() == this->_M_node_allocator())
1322 {
1323 if (__ht._M_uses_single_bucket())
1324 {
1325 _M_buckets = &_M_single_bucket;
1326 _M_single_bucket = __ht._M_single_bucket;
1327 }
1328 else
1329 _M_buckets = __ht._M_buckets;
1330
1331 _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
1332 // Update, if necessary, bucket pointing to before begin that hasn't
1333 // moved.
1334 if (_M_begin())
1335 _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1336 __ht._M_reset();
1337 }
1338 else
1339 {
1340 _M_assign(__ht,
1341 [this](__node_type* __n)
1342 {
1343 return this->_M_allocate_node(
1344 std::move_if_noexcept(__n->_M_v()));
1345 });
1346 __ht.clear();
1347 }
1348 }
1349
1350 template<typename _Key, typename _Value,
1351 typename _Alloc, typename _ExtractKey, typename _Equal,
1352 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1353 typename _Traits>
1354 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1355 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1356 ~_Hashtable() noexcept
1357 {
1358 clear();
1359 _M_deallocate_buckets();
1360 }
1361
1362 template<typename _Key, typename _Value,
1363 typename _Alloc, typename _ExtractKey, typename _Equal,
1364 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1365 typename _Traits>
1366 void
1367 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1368 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1369 swap(_Hashtable& __x)
1370 noexcept(__and_<__is_nothrow_swappable<_H1>,
1371 __is_nothrow_swappable<_Equal>>::value)
1372 {
1373 // The only base class with member variables is hash_code_base.
1374 // We define _Hash_code_base::_M_swap because different
1375 // specializations have different members.
1376 this->_M_swap(__x);
1377
1378 std::__alloc_on_swap(this->_M_node_allocator(), __x._M_node_allocator());
1379 std::swap(_M_rehash_policy, __x._M_rehash_policy);
1380
1381 // Deal properly with potentially moved instances.
1382 if (this->_M_uses_single_bucket())
1383 {
1384 if (!__x._M_uses_single_bucket())
1385 {
1386 _M_buckets = __x._M_buckets;
1387 __x._M_buckets = &__x._M_single_bucket;
1388 }
1389 }
1390 else if (__x._M_uses_single_bucket())
1391 {
1392 __x._M_buckets = _M_buckets;
1393 _M_buckets = &_M_single_bucket;
1394 }
1395 else
1396 std::swap(_M_buckets, __x._M_buckets);
1397
1398 std::swap(_M_bucket_count, __x._M_bucket_count);
1399 std::swap(_M_before_begin._M_nxt, __x._M_before_begin._M_nxt);
1400 std::swap(_M_element_count, __x._M_element_count);
1401 std::swap(_M_single_bucket, __x._M_single_bucket);
1402
1403 // Fix buckets containing the _M_before_begin pointers that can't be
1404 // swapped.
1405 if (_M_begin())
1406 _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1407
1408 if (__x._M_begin())
1409 __x._M_buckets[__x._M_bucket_index(__x._M_begin())]
1410 = &__x._M_before_begin;
1411 }
1412
1413 template<typename _Key, typename _Value,
1414 typename _Alloc, typename _ExtractKey, typename _Equal,
1415 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1416 typename _Traits>
1417 auto
1418 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1419 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1420 find(const key_type& __k)
1421 -> iterator
1422 {
1423 __hash_code __code = this->_M_hash_code(__k);
1424 std::size_t __n = _M_bucket_index(__k, __code);
1425 __node_type* __p = _M_find_node(__n, __k, __code);
1426 return __p ? iterator(__p) : end();
1427 }
1428
1429 template<typename _Key, typename _Value,
1430 typename _Alloc, typename _ExtractKey, typename _Equal,
1431 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1432 typename _Traits>
1433 auto
1434 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1435 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1436 find(const key_type& __k) const
1437 -> const_iterator
1438 {
1439 __hash_code __code = this->_M_hash_code(__k);
1440 std::size_t __n = _M_bucket_index(__k, __code);
1441 __node_type* __p = _M_find_node(__n, __k, __code);
1442 return __p ? const_iterator(__p) : end();
1443 }
1444
1445 template<typename _Key, typename _Value,
1446 typename _Alloc, typename _ExtractKey, typename _Equal,
1447 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1448 typename _Traits>
1449 auto
1450 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1451 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1452 count(const key_type& __k) const
1453 -> size_type
1454 {
1455 __hash_code __code = this->_M_hash_code(__k);
1456 std::size_t __n = _M_bucket_index(__k, __code);
1457 __node_type* __p = _M_bucket_begin(__n);
1458 if (!__p)
1459 return 0;
1460
1461 std::size_t __result = 0;
1462 for (;; __p = __p->_M_next())
1463 {
1464 if (this->_M_equals(__k, __code, __p))
1465 ++__result;
1466 else if (__result)
1467 // All equivalent values are next to each other, if we
1468 // found a non-equivalent value after an equivalent one it
1469 // means that we won't find any new equivalent value.
1470 break;
1471 if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
1472 break;
1473 }
1474 return __result;
1475 }
1476
1477 template<typename _Key, typename _Value,
1478 typename _Alloc, typename _ExtractKey, typename _Equal,
1479 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1480 typename _Traits>
1481 auto
1482 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1483 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1484 equal_range(const key_type& __k)
1485 -> pair<iterator, iterator>
1486 {
1487 __hash_code __code = this->_M_hash_code(__k);
1488 std::size_t __n = _M_bucket_index(__k, __code);
1489 __node_type* __p = _M_find_node(__n, __k, __code);
1490
1491 if (__p)
1492 {
1493 __node_type* __p1 = __p->_M_next();
1494 while (__p1 && _M_bucket_index(__p1) == __n
1495 && this->_M_equals(__k, __code, __p1))
1496 __p1 = __p1->_M_next();
1497
1498 return std::make_pair(iterator(__p), iterator(__p1));
1499 }
1500 else
1501 return std::make_pair(end(), end());
1502 }
1503
1504 template<typename _Key, typename _Value,
1505 typename _Alloc, typename _ExtractKey, typename _Equal,
1506 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1507 typename _Traits>
1508 auto
1509 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1510 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1511 equal_range(const key_type& __k) const
1512 -> pair<const_iterator, const_iterator>
1513 {
1514 __hash_code __code = this->_M_hash_code(__k);
1515 std::size_t __n = _M_bucket_index(__k, __code);
1516 __node_type* __p = _M_find_node(__n, __k, __code);
1517
1518 if (__p)
1519 {
1520 __node_type* __p1 = __p->_M_next();
1521 while (__p1 && _M_bucket_index(__p1) == __n
1522 && this->_M_equals(__k, __code, __p1))
1523 __p1 = __p1->_M_next();
1524
1525 return std::make_pair(const_iterator(__p), const_iterator(__p1));
1526 }
1527 else
1528 return std::make_pair(end(), end());
1529 }
1530
1531 // Find the node whose key compares equal to k in the bucket n.
1532 // Return nullptr if no node is found.
1533 template<typename _Key, typename _Value,
1534 typename _Alloc, typename _ExtractKey, typename _Equal,
1535 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1536 typename _Traits>
1537 auto
1538 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1539 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1540 _M_find_before_node(size_type __n, const key_type& __k,
1541 __hash_code __code) const
1542 -> __node_base*
1543 {
1544 __node_base* __prev_p = _M_buckets[__n];
1545 if (!__prev_p)
1546 return nullptr;
1547
1548 for (__node_type* __p = static_cast<__node_type*>(__prev_p->_M_nxt);;
1549 __p = __p->_M_next())
1550 {
1551 if (this->_M_equals(__k, __code, __p))
1552 return __prev_p;
1553
1554 if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
1555 break;
1556 __prev_p = __p;
1557 }
1558 return nullptr;
1559 }
1560
1561 template<typename _Key, typename _Value,
1562 typename _Alloc, typename _ExtractKey, typename _Equal,
1563 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1564 typename _Traits>
1565 void
1566 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1567 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1568 _M_insert_bucket_begin(size_type __bkt, __node_type* __node)
1569 {
1570 if (_M_buckets[__bkt])
1571 {
1572 // Bucket is not empty, we just need to insert the new node
1573 // after the bucket before begin.
1574 __node->_M_nxt = _M_buckets[__bkt]->_M_nxt;
1575 _M_buckets[__bkt]->_M_nxt = __node;
1576 }
1577 else
1578 {
1579 // The bucket is empty, the new node is inserted at the
1580 // beginning of the singly-linked list and the bucket will
1581 // contain _M_before_begin pointer.
1582 __node->_M_nxt = _M_before_begin._M_nxt;
1583 _M_before_begin._M_nxt = __node;
1584 if (__node->_M_nxt)
1585 // We must update former begin bucket that is pointing to
1586 // _M_before_begin.
1587 _M_buckets[_M_bucket_index(__node->_M_next())] = __node;
1588 _M_buckets[__bkt] = &_M_before_begin;
1589 }
1590 }
1591
1592 template<typename _Key, typename _Value,
1593 typename _Alloc, typename _ExtractKey, typename _Equal,
1594 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1595 typename _Traits>
1596 void
1597 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1598 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1599 _M_remove_bucket_begin(size_type __bkt, __node_type* __next,
1600 size_type __next_bkt)
1601 {
1602 if (!__next || __next_bkt != __bkt)
1603 {
1604 // Bucket is now empty
1605 // First update next bucket if any
1606 if (__next)
1607 _M_buckets[__next_bkt] = _M_buckets[__bkt];
1608
1609 // Second update before begin node if necessary
1610 if (&_M_before_begin == _M_buckets[__bkt])
1611 _M_before_begin._M_nxt = __next;
1612 _M_buckets[__bkt] = nullptr;
1613 }
1614 }
1615
1616 template<typename _Key, typename _Value,
1617 typename _Alloc, typename _ExtractKey, typename _Equal,
1618 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1619 typename _Traits>
1620 auto
1621 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1622 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1623 _M_get_previous_node(size_type __bkt, __node_base* __n)
1624 -> __node_base*
1625 {
1626 __node_base* __prev_n = _M_buckets[__bkt];
1627 while (__prev_n->_M_nxt != __n)
1628 __prev_n = __prev_n->_M_nxt;
1629 return __prev_n;
1630 }
1631
1632 template<typename _Key, typename _Value,
1633 typename _Alloc, typename _ExtractKey, typename _Equal,
1634 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1635 typename _Traits>
1636 template<typename... _Args>
1637 auto
1638 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1639 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1640 _M_emplace(std::true_type, _Args&&... __args)
1641 -> pair<iterator, bool>
1642 {
1643 // First build the node to get access to the hash code
1644 __node_type* __node = this->_M_allocate_node(std::forward<_Args>(__args)...);
1645 const key_type& __k = this->_M_extract()(__node->_M_v());
1646 __hash_code __code;
1647 __try
1648 {
1649 __code = this->_M_hash_code(__k);
1650 }
1651 __catch(...)
1652 {
1653 this->_M_deallocate_node(__node);
1654 __throw_exception_again;
1655 }
1656
1657 size_type __bkt = _M_bucket_index(__k, __code);
1658 if (__node_type* __p = _M_find_node(__bkt, __k, __code))
1659 {
1660 // There is already an equivalent node, no insertion
1661 this->_M_deallocate_node(__node);
1662 return std::make_pair(iterator(__p), false);
1663 }
1664
1665 // Insert the node
1666 return std::make_pair(_M_insert_unique_node(__bkt, __code, __node),
1667 true);
1668 }
1669
1670 template<typename _Key, typename _Value,
1671 typename _Alloc, typename _ExtractKey, typename _Equal,
1672 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1673 typename _Traits>
1674 template<typename... _Args>
1675 auto
1676 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1677 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1678 _M_emplace(const_iterator __hint, std::false_type, _Args&&... __args)
1679 -> iterator
1680 {
1681 // First build the node to get its hash code.
1682 __node_type* __node =
1683 this->_M_allocate_node(std::forward<_Args>(__args)...);
1684
1685 __hash_code __code;
1686 __try
1687 {
1688 __code = this->_M_hash_code(this->_M_extract()(__node->_M_v()));
1689 }
1690 __catch(...)
1691 {
1692 this->_M_deallocate_node(__node);
1693 __throw_exception_again;
1694 }
1695
1696 return _M_insert_multi_node(__hint._M_cur, __code, __node);
1697 }
1698
1699 template<typename _Key, typename _Value,
1700 typename _Alloc, typename _ExtractKey, typename _Equal,
1701 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1702 typename _Traits>
1703 auto
1704 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1705 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1706 _M_insert_unique_node(size_type __bkt, __hash_code __code,
1707 __node_type* __node)
1708 -> iterator
1709 {
1710 const __rehash_state& __saved_state = _M_rehash_policy._M_state();
1711 std::pair<bool, std::size_t> __do_rehash
1712 = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count, 1);
1713
1714 __try
1715 {
1716 if (__do_rehash.first)
1717 {
1718 _M_rehash(__do_rehash.second, __saved_state);
1719 __bkt = _M_bucket_index(this->_M_extract()(__node->_M_v()), __code);
1720 }
1721
1722 this->_M_store_code(__node, __code);
1723
1724 // Always insert at the beginning of the bucket.
1725 _M_insert_bucket_begin(__bkt, __node);
1726 ++_M_element_count;
1727 return iterator(__node);
1728 }
1729 __catch(...)
1730 {
1731 this->_M_deallocate_node(__node);
1732 __throw_exception_again;
1733 }
1734 }
1735
1736 // Insert node, in bucket bkt if no rehash (assumes no element with its key
1737 // already present). Take ownership of the node, deallocate it on exception.
1738 template<typename _Key, typename _Value,
1739 typename _Alloc, typename _ExtractKey, typename _Equal,
1740 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1741 typename _Traits>
1742 auto
1743 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1744 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1745 _M_insert_multi_node(__node_type* __hint, __hash_code __code,
1746 __node_type* __node)
1747 -> iterator
1748 {
1749 const __rehash_state& __saved_state = _M_rehash_policy._M_state();
1750 std::pair<bool, std::size_t> __do_rehash
1751 = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count, 1);
1752
1753 __try
1754 {
1755 if (__do_rehash.first)
1756 _M_rehash(__do_rehash.second, __saved_state);
1757
1758 this->_M_store_code(__node, __code);
1759 const key_type& __k = this->_M_extract()(__node->_M_v());
1760 size_type __bkt = _M_bucket_index(__k, __code);
1761
1762 // Find the node before an equivalent one or use hint if it exists and
1763 // if it is equivalent.
1764 __node_base* __prev
1765 = __builtin_expect(__hint != nullptr, false)
1766 && this->_M_equals(__k, __code, __hint)
1767 ? __hint
1768 : _M_find_before_node(__bkt, __k, __code);
1769 if (__prev)
1770 {
1771 // Insert after the node before the equivalent one.
1772 __node->_M_nxt = __prev->_M_nxt;
1773 __prev->_M_nxt = __node;
1774 if (__builtin_expect(__prev == __hint, false))
1775 // hint might be the last bucket node, in this case we need to
1776 // update next bucket.
1777 if (__node->_M_nxt
1778 && !this->_M_equals(__k, __code, __node->_M_next()))
1779 {
1780 size_type __next_bkt = _M_bucket_index(__node->_M_next());
1781 if (__next_bkt != __bkt)
1782 _M_buckets[__next_bkt] = __node;
1783 }
1784 }
1785 else
1786 // The inserted node has no equivalent in the
1787 // hashtable. We must insert the new node at the
1788 // beginning of the bucket to preserve equivalent
1789 // elements' relative positions.
1790 _M_insert_bucket_begin(__bkt, __node);
1791 ++_M_element_count;
1792 return iterator(__node);
1793 }
1794 __catch(...)
1795 {
1796 this->_M_deallocate_node(__node);
1797 __throw_exception_again;
1798 }
1799 }
1800
1801 // Insert v if no element with its key is already present.
1802 template<typename _Key, typename _Value,
1803 typename _Alloc, typename _ExtractKey, typename _Equal,
1804 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1805 typename _Traits>
1806 template<typename _Arg, typename _NodeGenerator>
1807 auto
1808 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1809 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1810 _M_insert(_Arg&& __v, const _NodeGenerator& __node_gen, std::true_type)
1811 -> pair<iterator, bool>
1812 {
1813 const key_type& __k = this->_M_extract()(__v);
1814 __hash_code __code = this->_M_hash_code(__k);
1815 size_type __bkt = _M_bucket_index(__k, __code);
1816
1817 __node_type* __n = _M_find_node(__bkt, __k, __code);
1818 if (__n)
1819 return std::make_pair(iterator(__n), false);
1820
1821 __n = __node_gen(std::forward<_Arg>(__v));
1822 return std::make_pair(_M_insert_unique_node(__bkt, __code, __n), true);
1823 }
1824
1825 // Insert v unconditionally.
1826 template<typename _Key, typename _Value,
1827 typename _Alloc, typename _ExtractKey, typename _Equal,
1828 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1829 typename _Traits>
1830 template<typename _Arg, typename _NodeGenerator>
1831 auto
1832 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1833 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1834 _M_insert(const_iterator __hint, _Arg&& __v,
1835 const _NodeGenerator& __node_gen, std::false_type)
1836 -> iterator
1837 {
1838 // First compute the hash code so that we don't do anything if it
1839 // throws.
1840 __hash_code __code = this->_M_hash_code(this->_M_extract()(__v));
1841
1842 // Second allocate new node so that we don't rehash if it throws.
1843 __node_type* __node = __node_gen(std::forward<_Arg>(__v));
1844
1845 return _M_insert_multi_node(__hint._M_cur, __code, __node);
1846 }
1847
1848 template<typename _Key, typename _Value,
1849 typename _Alloc, typename _ExtractKey, typename _Equal,
1850 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1851 typename _Traits>
1852 auto
1853 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1854 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1855 erase(const_iterator __it)
1856 -> iterator
1857 {
1858 __node_type* __n = __it._M_cur;
1859 std::size_t __bkt = _M_bucket_index(__n);
1860
1861 // Look for previous node to unlink it from the erased one, this
1862 // is why we need buckets to contain the before begin to make
1863 // this search fast.
1864 __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
1865 return _M_erase(__bkt, __prev_n, __n);
1866 }
1867
1868 template<typename _Key, typename _Value,
1869 typename _Alloc, typename _ExtractKey, typename _Equal,
1870 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1871 typename _Traits>
1872 auto
1873 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1874 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1875 _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n)
1876 -> iterator
1877 {
1878 if (__prev_n == _M_buckets[__bkt])
1879 _M_remove_bucket_begin(__bkt, __n->_M_next(),
1880 __n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
1881 else if (__n->_M_nxt)
1882 {
1883 size_type __next_bkt = _M_bucket_index(__n->_M_next());
1884 if (__next_bkt != __bkt)
1885 _M_buckets[__next_bkt] = __prev_n;
1886 }
1887
1888 __prev_n->_M_nxt = __n->_M_nxt;
1889 iterator __result(__n->_M_next());
1890 this->_M_deallocate_node(__n);
1891 --_M_element_count;
1892
1893 return __result;
1894 }
1895
1896 template<typename _Key, typename _Value,
1897 typename _Alloc, typename _ExtractKey, typename _Equal,
1898 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1899 typename _Traits>
1900 auto
1901 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1902 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1903 _M_erase(std::true_type, const key_type& __k)
1904 -> size_type
1905 {
1906 __hash_code __code = this->_M_hash_code(__k);
1907 std::size_t __bkt = _M_bucket_index(__k, __code);
1908
1909 // Look for the node before the first matching node.
1910 __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
1911 if (!__prev_n)
1912 return 0;
1913
1914 // We found a matching node, erase it.
1915 __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
1916 _M_erase(__bkt, __prev_n, __n);
1917 return 1;
1918 }
1919
1920 template<typename _Key, typename _Value,
1921 typename _Alloc, typename _ExtractKey, typename _Equal,
1922 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1923 typename _Traits>
1924 auto
1925 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1926 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1927 _M_erase(std::false_type, const key_type& __k)
1928 -> size_type
1929 {
1930 __hash_code __code = this->_M_hash_code(__k);
1931 std::size_t __bkt = _M_bucket_index(__k, __code);
1932
1933 // Look for the node before the first matching node.
1934 __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
1935 if (!__prev_n)
1936 return 0;
1937
1938 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1939 // 526. Is it undefined if a function in the standard changes
1940 // in parameters?
1941 // We use one loop to find all matching nodes and another to deallocate
1942 // them so that the key stays valid during the first loop. It might be
1943 // invalidated indirectly when destroying nodes.
1944 __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
1945 __node_type* __n_last = __n;
1946 std::size_t __n_last_bkt = __bkt;
1947 do
1948 {
1949 __n_last = __n_last->_M_next();
1950 if (!__n_last)
1951 break;
1952 __n_last_bkt = _M_bucket_index(__n_last);
1953 }
1954 while (__n_last_bkt == __bkt && this->_M_equals(__k, __code, __n_last));
1955
1956 // Deallocate nodes.
1957 size_type __result = 0;
1958 do
1959 {
1960 __node_type* __p = __n->_M_next();
1961 this->_M_deallocate_node(__n);
1962 __n = __p;
1963 ++__result;
1964 --_M_element_count;
1965 }
1966 while (__n != __n_last);
1967
1968 if (__prev_n == _M_buckets[__bkt])
1969 _M_remove_bucket_begin(__bkt, __n_last, __n_last_bkt);
1970 else if (__n_last && __n_last_bkt != __bkt)
1971 _M_buckets[__n_last_bkt] = __prev_n;
1972 __prev_n->_M_nxt = __n_last;
1973 return __result;
1974 }
1975
1976 template<typename _Key, typename _Value,
1977 typename _Alloc, typename _ExtractKey, typename _Equal,
1978 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1979 typename _Traits>
1980 auto
1981 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1982 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1983 erase(const_iterator __first, const_iterator __last)
1984 -> iterator
1985 {
1986 __node_type* __n = __first._M_cur;
1987 __node_type* __last_n = __last._M_cur;
1988 if (__n == __last_n)
1989 return iterator(__n);
1990
1991 std::size_t __bkt = _M_bucket_index(__n);
1992
1993 __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
1994 bool __is_bucket_begin = __n == _M_bucket_begin(__bkt);
1995 std::size_t __n_bkt = __bkt;
1996 for (;;)
1997 {
1998 do
1999 {
2000 __node_type* __tmp = __n;
2001 __n = __n->_M_next();
2002 this->_M_deallocate_node(__tmp);
2003 --_M_element_count;
2004 if (!__n)
2005 break;
2006 __n_bkt = _M_bucket_index(__n);
2007 }
2008 while (__n != __last_n && __n_bkt == __bkt);
2009 if (__is_bucket_begin)
2010 _M_remove_bucket_begin(__bkt, __n, __n_bkt);
2011 if (__n == __last_n)
2012 break;
2013 __is_bucket_begin = true;
2014 __bkt = __n_bkt;
2015 }
2016
2017 if (__n && (__n_bkt != __bkt || __is_bucket_begin))
2018 _M_buckets[__n_bkt] = __prev_n;
2019 __prev_n->_M_nxt = __n;
2020 return iterator(__n);
2021 }
2022
2023 template<typename _Key, typename _Value,
2024 typename _Alloc, typename _ExtractKey, typename _Equal,
2025 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2026 typename _Traits>
2027 void
2028 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2029 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2030 clear() noexcept
2031 {
2032 this->_M_deallocate_nodes(_M_begin());
2033 __builtin_memset(_M_buckets, 0, _M_bucket_count * sizeof(__bucket_type));
2034 _M_element_count = 0;
2035 _M_before_begin._M_nxt = nullptr;
2036 }
2037
2038 template<typename _Key, typename _Value,
2039 typename _Alloc, typename _ExtractKey, typename _Equal,
2040 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2041 typename _Traits>
2042 void
2043 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2044 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2045 rehash(size_type __n)
2046 {
2047 const __rehash_state& __saved_state = _M_rehash_policy._M_state();
2048 std::size_t __buckets
2049 = std::max(_M_rehash_policy._M_bkt_for_elements(_M_element_count + 1),
2050 __n);
2051 __buckets = _M_rehash_policy._M_next_bkt(__buckets);
2052
2053 if (__buckets != _M_bucket_count)
2054 _M_rehash(__buckets, __saved_state);
2055 else
2056 // No rehash, restore previous state to keep a consistent state.
2057 _M_rehash_policy._M_reset(__saved_state);
2058 }
2059
2060 template<typename _Key, typename _Value,
2061 typename _Alloc, typename _ExtractKey, typename _Equal,
2062 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2063 typename _Traits>
2064 void
2065 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2066 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2067 _M_rehash(size_type __n, const __rehash_state& __state)
2068 {
2069 __try
2070 {
2071 _M_rehash_aux(__n, __unique_keys());
2072 }
2073 __catch(...)
2074 {
2075 // A failure here means that buckets allocation failed. We only
2076 // have to restore hash policy previous state.
2077 _M_rehash_policy._M_reset(__state);
2078 __throw_exception_again;
2079 }
2080 }
2081
2082 // Rehash when there is no equivalent elements.
2083 template<typename _Key, typename _Value,
2084 typename _Alloc, typename _ExtractKey, typename _Equal,
2085 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2086 typename _Traits>
2087 void
2088 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2089 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2090 _M_rehash_aux(size_type __n, std::true_type)
2091 {
2092 __bucket_type* __new_buckets = _M_allocate_buckets(__n);
2093 __node_type* __p = _M_begin();
2094 _M_before_begin._M_nxt = nullptr;
2095 std::size_t __bbegin_bkt = 0;
2096 while (__p)
2097 {
2098 __node_type* __next = __p->_M_next();
2099 std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
2100 if (!__new_buckets[__bkt])
2101 {
2102 __p->_M_nxt = _M_before_begin._M_nxt;
2103 _M_before_begin._M_nxt = __p;
2104 __new_buckets[__bkt] = &_M_before_begin;
2105 if (__p->_M_nxt)
2106 __new_buckets[__bbegin_bkt] = __p;
2107 __bbegin_bkt = __bkt;
2108 }
2109 else
2110 {
2111 __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2112 __new_buckets[__bkt]->_M_nxt = __p;
2113 }
2114 __p = __next;
2115 }
2116
2117 _M_deallocate_buckets();
2118 _M_bucket_count = __n;
2119 _M_buckets = __new_buckets;
2120 }
2121
2122 // Rehash when there can be equivalent elements, preserve their relative
2123 // order.
2124 template<typename _Key, typename _Value,
2125 typename _Alloc, typename _ExtractKey, typename _Equal,
2126 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2127 typename _Traits>
2128 void
2129 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2130 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2131 _M_rehash_aux(size_type __n, std::false_type)
2132 {
2133 __bucket_type* __new_buckets = _M_allocate_buckets(__n);
2134
2135 __node_type* __p = _M_begin();
2136 _M_before_begin._M_nxt = nullptr;
2137 std::size_t __bbegin_bkt = 0;
2138 std::size_t __prev_bkt = 0;
2139 __node_type* __prev_p = nullptr;
2140 bool __check_bucket = false;
2141
2142 while (__p)
2143 {
2144 __node_type* __next = __p->_M_next();
2145 std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
2146
2147 if (__prev_p && __prev_bkt == __bkt)
2148 {
2149 // Previous insert was already in this bucket, we insert after
2150 // the previously inserted one to preserve equivalent elements
2151 // relative order.
2152 __p->_M_nxt = __prev_p->_M_nxt;
2153 __prev_p->_M_nxt = __p;
2154
2155 // Inserting after a node in a bucket require to check that we
2156 // haven't change the bucket last node, in this case next
2157 // bucket containing its before begin node must be updated. We
2158 // schedule a check as soon as we move out of the sequence of
2159 // equivalent nodes to limit the number of checks.
2160 __check_bucket = true;
2161 }
2162 else
2163 {
2164 if (__check_bucket)
2165 {
2166 // Check if we shall update the next bucket because of
2167 // insertions into __prev_bkt bucket.
2168 if (__prev_p->_M_nxt)
2169 {
2170 std::size_t __next_bkt
2171 = __hash_code_base::_M_bucket_index(__prev_p->_M_next(),
2172 __n);
2173 if (__next_bkt != __prev_bkt)
2174 __new_buckets[__next_bkt] = __prev_p;
2175 }
2176 __check_bucket = false;
2177 }
2178
2179 if (!__new_buckets[__bkt])
2180 {
2181 __p->_M_nxt = _M_before_begin._M_nxt;
2182 _M_before_begin._M_nxt = __p;
2183 __new_buckets[__bkt] = &_M_before_begin;
2184 if (__p->_M_nxt)
2185 __new_buckets[__bbegin_bkt] = __p;
2186 __bbegin_bkt = __bkt;
2187 }
2188 else
2189 {
2190 __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2191 __new_buckets[__bkt]->_M_nxt = __p;
2192 }
2193 }
2194 __prev_p = __p;
2195 __prev_bkt = __bkt;
2196 __p = __next;
2197 }
2198
2199 if (__check_bucket && __prev_p->_M_nxt)
2200 {
2201 std::size_t __next_bkt
2202 = __hash_code_base::_M_bucket_index(__prev_p->_M_next(), __n);
2203 if (__next_bkt != __prev_bkt)
2204 __new_buckets[__next_bkt] = __prev_p;
2205 }
2206
2207 _M_deallocate_buckets();
2208 _M_bucket_count = __n;
2209 _M_buckets = __new_buckets;
2210 }
2211
2212#if __cplusplus > 201402L
2213 template<typename, typename, typename> class _Hash_merge_helper { };
2214#endif // C++17
2215
2216_GLIBCXX_END_NAMESPACE_VERSION
2217} // namespace std
2218
2219#endif // _HASHTABLE_H
2220