1// hashtable.h header -*- C++ -*-
2
3// Copyright (C) 2007-2019 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 __is_nothrow_invocable<const _Hash&, const _Tp&>>>;
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 static_assert(is_same<typename remove_cv<_Value>::type, _Value>::value,
190 "unordered container must have a non-const, non-volatile value_type");
191#ifdef __STRICT_ANSI__
192 static_assert(is_same<typename _Alloc::value_type, _Value>{},
193 "unordered container must have the same value_type as its allocator");
194#endif
195
196 using __traits_type = _Traits;
197 using __hash_cached = typename __traits_type::__hash_cached;
198 using __node_type = __detail::_Hash_node<_Value, __hash_cached::value>;
199 using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>;
200
201 using __hashtable_alloc = __detail::_Hashtable_alloc<__node_alloc_type>;
202
203 using __value_alloc_traits =
204 typename __hashtable_alloc::__value_alloc_traits;
205 using __node_alloc_traits =
206 typename __hashtable_alloc::__node_alloc_traits;
207 using __node_base = typename __hashtable_alloc::__node_base;
208 using __bucket_type = typename __hashtable_alloc::__bucket_type;
209
210 public:
211 typedef _Key key_type;
212 typedef _Value value_type;
213 typedef _Alloc allocator_type;
214 typedef _Equal key_equal;
215
216 // mapped_type, if present, comes from _Map_base.
217 // hasher, if present, comes from _Hash_code_base/_Hashtable_base.
218 typedef typename __value_alloc_traits::pointer pointer;
219 typedef typename __value_alloc_traits::const_pointer const_pointer;
220 typedef value_type& reference;
221 typedef const value_type& const_reference;
222
223 private:
224 using __rehash_type = _RehashPolicy;
225 using __rehash_state = typename __rehash_type::_State;
226
227 using __constant_iterators = typename __traits_type::__constant_iterators;
228 using __unique_keys = typename __traits_type::__unique_keys;
229
230 using __key_extract = typename std::conditional<
231 __constant_iterators::value,
232 __detail::_Identity,
233 __detail::_Select1st>::type;
234
235 using __hashtable_base = __detail::
236 _Hashtable_base<_Key, _Value, _ExtractKey,
237 _Equal, _H1, _H2, _Hash, _Traits>;
238
239 using __hash_code_base = typename __hashtable_base::__hash_code_base;
240 using __hash_code = typename __hashtable_base::__hash_code;
241 using __ireturn_type = typename __hashtable_base::__ireturn_type;
242
243 using __map_base = __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey,
244 _Equal, _H1, _H2, _Hash,
245 _RehashPolicy, _Traits>;
246
247 using __rehash_base = __detail::_Rehash_base<_Key, _Value, _Alloc,
248 _ExtractKey, _Equal,
249 _H1, _H2, _Hash,
250 _RehashPolicy, _Traits>;
251
252 using __eq_base = __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey,
253 _Equal, _H1, _H2, _Hash,
254 _RehashPolicy, _Traits>;
255
256 using __reuse_or_alloc_node_type =
257 __detail::_ReuseOrAllocNode<__node_alloc_type>;
258
259 // Metaprogramming for picking apart hash caching.
260 template<typename _Cond>
261 using __if_hash_cached = __or_<__not_<__hash_cached>, _Cond>;
262
263 template<typename _Cond>
264 using __if_hash_not_cached = __or_<__hash_cached, _Cond>;
265
266 // Compile-time diagnostics.
267
268 // _Hash_code_base has everything protected, so use this derived type to
269 // access it.
270 struct __hash_code_base_access : __hash_code_base
271 { using __hash_code_base::_M_bucket_index; };
272
273 // Getting a bucket index from a node shall not throw because it is used
274 // in methods (erase, swap...) that shall not throw.
275 static_assert(noexcept(declval<const __hash_code_base_access&>()
276 ._M_bucket_index((const __node_type*)nullptr,
277 (std::size_t)0)),
278 "Cache the hash code or qualify your functors involved"
279 " in hash code and bucket index computation with noexcept");
280
281 // Following two static assertions are necessary to guarantee
282 // that local_iterator will be default constructible.
283
284 // When hash codes are cached local iterator inherits from H2 functor
285 // which must then be default constructible.
286 static_assert(__if_hash_cached<is_default_constructible<_H2>>::value,
287 "Functor used to map hash code to bucket index"
288 " must be default constructible");
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 bool _Unique_keysa>
295 friend struct __detail::_Map_base;
296
297 template<typename _Keya, typename _Valuea, typename _Alloca,
298 typename _ExtractKeya, typename _Equala,
299 typename _H1a, typename _H2a, typename _Hasha,
300 typename _RehashPolicya, typename _Traitsa>
301 friend struct __detail::_Insert_base;
302
303 template<typename _Keya, typename _Valuea, typename _Alloca,
304 typename _ExtractKeya, typename _Equala,
305 typename _H1a, typename _H2a, typename _Hasha,
306 typename _RehashPolicya, typename _Traitsa,
307 bool _Constant_iteratorsa>
308 friend struct __detail::_Insert;
309
310 public:
311 using size_type = typename __hashtable_base::size_type;
312 using difference_type = typename __hashtable_base::difference_type;
313
314 using iterator = typename __hashtable_base::iterator;
315 using const_iterator = typename __hashtable_base::const_iterator;
316
317 using local_iterator = typename __hashtable_base::local_iterator;
318 using const_local_iterator = typename __hashtable_base::
319 const_local_iterator;
320
321#if __cplusplus > 201402L
322 using node_type = _Node_handle<_Key, _Value, __node_alloc_type>;
323 using insert_return_type = _Node_insert_return<iterator, node_type>;
324#endif
325
326 private:
327 __bucket_type* _M_buckets = &_M_single_bucket;
328 size_type _M_bucket_count = 1;
329 __node_base _M_before_begin;
330 size_type _M_element_count = 0;
331 _RehashPolicy _M_rehash_policy;
332
333 // A single bucket used when only need for 1 bucket. Especially
334 // interesting in move semantic to leave hashtable with only 1 buckets
335 // which is not allocated so that we can have those operations noexcept
336 // qualified.
337 // Note that we can't leave hashtable with 0 bucket without adding
338 // numerous checks in the code to avoid 0 modulus.
339 __bucket_type _M_single_bucket = nullptr;
340
341 bool
342 _M_uses_single_bucket(__bucket_type* __bkts) const
343 { return __builtin_expect(__bkts == &_M_single_bucket, false); }
344
345 bool
346 _M_uses_single_bucket() const
347 { return _M_uses_single_bucket(_M_buckets); }
348
349 __hashtable_alloc&
350 _M_base_alloc() { return *this; }
351
352 __bucket_type*
353 _M_allocate_buckets(size_type __n)
354 {
355 if (__builtin_expect(__n == 1, false))
356 {
357 _M_single_bucket = nullptr;
358 return &_M_single_bucket;
359 }
360
361 return __hashtable_alloc::_M_allocate_buckets(__n);
362 }
363
364 void
365 _M_deallocate_buckets(__bucket_type* __bkts, size_type __n)
366 {
367 if (_M_uses_single_bucket(__bkts))
368 return;
369
370 __hashtable_alloc::_M_deallocate_buckets(__bkts, __n);
371 }
372
373 void
374 _M_deallocate_buckets()
375 { _M_deallocate_buckets(_M_buckets, _M_bucket_count); }
376
377 // Gets bucket begin, deals with the fact that non-empty buckets contain
378 // their before begin node.
379 __node_type*
380 _M_bucket_begin(size_type __bkt) const;
381
382 __node_type*
383 _M_begin() const
384 { return static_cast<__node_type*>(_M_before_begin._M_nxt); }
385
386 // Assign *this using another _Hashtable instance. Either elements
387 // are copy or move depends on the _NodeGenerator.
388 template<typename _Ht, typename _NodeGenerator>
389 void
390 _M_assign_elements(_Ht&&, const _NodeGenerator&);
391
392 template<typename _NodeGenerator>
393 void
394 _M_assign(const _Hashtable&, const _NodeGenerator&);
395
396 void
397 _M_move_assign(_Hashtable&&, std::true_type);
398
399 void
400 _M_move_assign(_Hashtable&&, std::false_type);
401
402 void
403 _M_reset() noexcept;
404
405 _Hashtable(const _H1& __h1, const _H2& __h2, const _Hash& __h,
406 const _Equal& __eq, const _ExtractKey& __exk,
407 const allocator_type& __a)
408 : __hashtable_base(__exk, __h1, __h2, __h, __eq),
409 __hashtable_alloc(__node_alloc_type(__a))
410 { }
411
412 public:
413 // Constructor, destructor, assignment, swap
414 _Hashtable() = default;
415 _Hashtable(size_type __bucket_hint,
416 const _H1&, const _H2&, const _Hash&,
417 const _Equal&, const _ExtractKey&,
418 const allocator_type&);
419
420 template<typename _InputIterator>
421 _Hashtable(_InputIterator __first, _InputIterator __last,
422 size_type __bucket_hint,
423 const _H1&, const _H2&, const _Hash&,
424 const _Equal&, const _ExtractKey&,
425 const allocator_type&);
426
427 _Hashtable(const _Hashtable&);
428
429 _Hashtable(_Hashtable&&) noexcept;
430
431 _Hashtable(const _Hashtable&, const allocator_type&);
432
433 _Hashtable(_Hashtable&&, const allocator_type&);
434
435 // Use delegating constructors.
436 explicit
437 _Hashtable(const allocator_type& __a)
438 : __hashtable_alloc(__node_alloc_type(__a))
439 { }
440
441 explicit
442 _Hashtable(size_type __n,
443 const _H1& __hf = _H1(),
444 const key_equal& __eql = key_equal(),
445 const allocator_type& __a = allocator_type())
446 : _Hashtable(__n, __hf, _H2(), _Hash(), __eql,
447 __key_extract(), __a)
448 { }
449
450 template<typename _InputIterator>
451 _Hashtable(_InputIterator __f, _InputIterator __l,
452 size_type __n = 0,
453 const _H1& __hf = _H1(),
454 const key_equal& __eql = key_equal(),
455 const allocator_type& __a = allocator_type())
456 : _Hashtable(__f, __l, __n, __hf, _H2(), _Hash(), __eql,
457 __key_extract(), __a)
458 { }
459
460 _Hashtable(initializer_list<value_type> __l,
461 size_type __n = 0,
462 const _H1& __hf = _H1(),
463 const key_equal& __eql = key_equal(),
464 const allocator_type& __a = allocator_type())
465 : _Hashtable(__l.begin(), __l.end(), __n, __hf, _H2(), _Hash(), __eql,
466 __key_extract(), __a)
467 { }
468
469 _Hashtable&
470 operator=(const _Hashtable& __ht);
471
472 _Hashtable&
473 operator=(_Hashtable&& __ht)
474 noexcept(__node_alloc_traits::_S_nothrow_move()
475 && is_nothrow_move_assignable<_H1>::value
476 && is_nothrow_move_assignable<_Equal>::value)
477 {
478 constexpr bool __move_storage =
479 __node_alloc_traits::_S_propagate_on_move_assign()
480 || __node_alloc_traits::_S_always_equal();
481 _M_move_assign(std::move(__ht), __bool_constant<__move_storage>());
482 return *this;
483 }
484
485 _Hashtable&
486 operator=(initializer_list<value_type> __l)
487 {
488 __reuse_or_alloc_node_type __roan(_M_begin(), *this);
489 _M_before_begin._M_nxt = nullptr;
490 clear();
491 this->_M_insert_range(__l.begin(), __l.end(), __roan, __unique_keys());
492 return *this;
493 }
494
495 ~_Hashtable() noexcept;
496
497 void
498 swap(_Hashtable&)
499 noexcept(__and_<__is_nothrow_swappable<_H1>,
500 __is_nothrow_swappable<_Equal>>::value);
501
502 // Basic container operations
503 iterator
504 begin() noexcept
505 { return iterator(_M_begin()); }
506
507 const_iterator
508 begin() const noexcept
509 { return const_iterator(_M_begin()); }
510
511 iterator
512 end() noexcept
513 { return iterator(nullptr); }
514
515 const_iterator
516 end() const noexcept
517 { return const_iterator(nullptr); }
518
519 const_iterator
520 cbegin() const noexcept
521 { return const_iterator(_M_begin()); }
522
523 const_iterator
524 cend() const noexcept
525 { return const_iterator(nullptr); }
526
527 size_type
528 size() const noexcept
529 { return _M_element_count; }
530
531 _GLIBCXX_NODISCARD bool
532 empty() const noexcept
533 { return size() == 0; }
534
535 allocator_type
536 get_allocator() const noexcept
537 { return allocator_type(this->_M_node_allocator()); }
538
539 size_type
540 max_size() const noexcept
541 { return __node_alloc_traits::max_size(this->_M_node_allocator()); }
542
543 // Observers
544 key_equal
545 key_eq() const
546 { return this->_M_eq(); }
547
548 // hash_function, if present, comes from _Hash_code_base.
549
550 // Bucket operations
551 size_type
552 bucket_count() const noexcept
553 { return _M_bucket_count; }
554
555 size_type
556 max_bucket_count() const noexcept
557 { return max_size(); }
558
559 size_type
560 bucket_size(size_type __n) const
561 { return std::distance(begin(__n), end(__n)); }
562
563 size_type
564 bucket(const key_type& __k) const
565 { return _M_bucket_index(__k, this->_M_hash_code(__k)); }
566
567 local_iterator
568 begin(size_type __n)
569 {
570 return local_iterator(*this, _M_bucket_begin(__n),
571 __n, _M_bucket_count);
572 }
573
574 local_iterator
575 end(size_type __n)
576 { return local_iterator(*this, nullptr, __n, _M_bucket_count); }
577
578 const_local_iterator
579 begin(size_type __n) const
580 {
581 return const_local_iterator(*this, _M_bucket_begin(__n),
582 __n, _M_bucket_count);
583 }
584
585 const_local_iterator
586 end(size_type __n) const
587 { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
588
589 // DR 691.
590 const_local_iterator
591 cbegin(size_type __n) const
592 {
593 return const_local_iterator(*this, _M_bucket_begin(__n),
594 __n, _M_bucket_count);
595 }
596
597 const_local_iterator
598 cend(size_type __n) const
599 { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
600
601 float
602 load_factor() const noexcept
603 {
604 return static_cast<float>(size()) / static_cast<float>(bucket_count());
605 }
606
607 // max_load_factor, if present, comes from _Rehash_base.
608
609 // Generalization of max_load_factor. Extension, not found in
610 // TR1. Only useful if _RehashPolicy is something other than
611 // the default.
612 const _RehashPolicy&
613 __rehash_policy() const
614 { return _M_rehash_policy; }
615
616 void
617 __rehash_policy(const _RehashPolicy& __pol)
618 { _M_rehash_policy = __pol; }
619
620 // Lookup.
621 iterator
622 find(const key_type& __k);
623
624 const_iterator
625 find(const key_type& __k) const;
626
627 size_type
628 count(const key_type& __k) const;
629
630 std::pair<iterator, iterator>
631 equal_range(const key_type& __k);
632
633 std::pair<const_iterator, const_iterator>
634 equal_range(const key_type& __k) const;
635
636 protected:
637 // Bucket index computation helpers.
638 size_type
639 _M_bucket_index(__node_type* __n) const noexcept
640 { return __hash_code_base::_M_bucket_index(__n, _M_bucket_count); }
641
642 size_type
643 _M_bucket_index(const key_type& __k, __hash_code __c) const
644 { return __hash_code_base::_M_bucket_index(__k, __c, _M_bucket_count); }
645
646 // Find and insert helper functions and types
647 // Find the node before the one matching the criteria.
648 __node_base*
649 _M_find_before_node(size_type, const key_type&, __hash_code) const;
650
651 __node_type*
652 _M_find_node(size_type __bkt, const key_type& __key,
653 __hash_code __c) const
654 {
655 __node_base* __before_n = _M_find_before_node(__bkt, __key, __c);
656 if (__before_n)
657 return static_cast<__node_type*>(__before_n->_M_nxt);
658 return nullptr;
659 }
660
661 // Insert a node at the beginning of a bucket.
662 void
663 _M_insert_bucket_begin(size_type, __node_type*);
664
665 // Remove the bucket first node
666 void
667 _M_remove_bucket_begin(size_type __bkt, __node_type* __next_n,
668 size_type __next_bkt);
669
670 // Get the node before __n in the bucket __bkt
671 __node_base*
672 _M_get_previous_node(size_type __bkt, __node_base* __n);
673
674 // Insert node with hash code __code, in bucket bkt if no rehash (assumes
675 // no element with its key already present). Take ownership of the node,
676 // deallocate it on exception.
677 iterator
678 _M_insert_unique_node(size_type __bkt, __hash_code __code,
679 __node_type* __n, size_type __n_elt = 1);
680
681 // Insert node with hash code __code. Take ownership of the node,
682 // deallocate it on exception.
683 iterator
684 _M_insert_multi_node(__node_type* __hint,
685 __hash_code __code, __node_type* __n);
686
687 template<typename... _Args>
688 std::pair<iterator, bool>
689 _M_emplace(std::true_type, _Args&&... __args);
690
691 template<typename... _Args>
692 iterator
693 _M_emplace(std::false_type __uk, _Args&&... __args)
694 { return _M_emplace(cend(), __uk, std::forward<_Args>(__args)...); }
695
696 // Emplace with hint, useless when keys are unique.
697 template<typename... _Args>
698 iterator
699 _M_emplace(const_iterator, std::true_type __uk, _Args&&... __args)
700 { return _M_emplace(__uk, std::forward<_Args>(__args)...).first; }
701
702 template<typename... _Args>
703 iterator
704 _M_emplace(const_iterator, std::false_type, _Args&&... __args);
705
706 template<typename _Arg, typename _NodeGenerator>
707 std::pair<iterator, bool>
708 _M_insert(_Arg&&, const _NodeGenerator&, true_type, size_type = 1);
709
710 template<typename _Arg, typename _NodeGenerator>
711 iterator
712 _M_insert(_Arg&& __arg, const _NodeGenerator& __node_gen,
713 false_type __uk)
714 {
715 return _M_insert(cend(), std::forward<_Arg>(__arg), __node_gen,
716 __uk);
717 }
718
719 // Insert with hint, not used when keys are unique.
720 template<typename _Arg, typename _NodeGenerator>
721 iterator
722 _M_insert(const_iterator, _Arg&& __arg,
723 const _NodeGenerator& __node_gen, true_type __uk)
724 {
725 return
726 _M_insert(std::forward<_Arg>(__arg), __node_gen, __uk).first;
727 }
728
729 // Insert with hint when keys are not unique.
730 template<typename _Arg, typename _NodeGenerator>
731 iterator
732 _M_insert(const_iterator, _Arg&&,
733 const _NodeGenerator&, false_type);
734
735 size_type
736 _M_erase(std::true_type, const key_type&);
737
738 size_type
739 _M_erase(std::false_type, const key_type&);
740
741 iterator
742 _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n);
743
744 public:
745 // Emplace
746 template<typename... _Args>
747 __ireturn_type
748 emplace(_Args&&... __args)
749 { return _M_emplace(__unique_keys(), std::forward<_Args>(__args)...); }
750
751 template<typename... _Args>
752 iterator
753 emplace_hint(const_iterator __hint, _Args&&... __args)
754 {
755 return _M_emplace(__hint, __unique_keys(),
756 std::forward<_Args>(__args)...);
757 }
758
759 // Insert member functions via inheritance.
760
761 // Erase
762 iterator
763 erase(const_iterator);
764
765 // LWG 2059.
766 iterator
767 erase(iterator __it)
768 { return erase(const_iterator(__it)); }
769
770 size_type
771 erase(const key_type& __k)
772 { return _M_erase(__unique_keys(), __k); }
773
774 iterator
775 erase(const_iterator, const_iterator);
776
777 void
778 clear() noexcept;
779
780 // Set number of buckets to be appropriate for container of n element.
781 void rehash(size_type __n);
782
783 // DR 1189.
784 // reserve, if present, comes from _Rehash_base.
785
786#if __cplusplus > 201402L
787 /// Re-insert an extracted node into a container with unique keys.
788 insert_return_type
789 _M_reinsert_node(node_type&& __nh)
790 {
791 insert_return_type __ret;
792 if (__nh.empty())
793 __ret.position = end();
794 else
795 {
796 __glibcxx_assert(get_allocator() == __nh.get_allocator());
797
798 const key_type& __k = __nh._M_key();
799 __hash_code __code = this->_M_hash_code(__k);
800 size_type __bkt = _M_bucket_index(__k, __code);
801 if (__node_type* __n = _M_find_node(__bkt, __k, __code))
802 {
803 __ret.node = std::move(__nh);
804 __ret.position = iterator(__n);
805 __ret.inserted = false;
806 }
807 else
808 {
809 __ret.position
810 = _M_insert_unique_node(__bkt, __code, __nh._M_ptr);
811 __nh._M_ptr = nullptr;
812 __ret.inserted = true;
813 }
814 }
815 return __ret;
816 }
817
818 /// Re-insert an extracted node into a container with equivalent keys.
819 iterator
820 _M_reinsert_node_multi(const_iterator __hint, node_type&& __nh)
821 {
822 iterator __ret;
823 if (__nh.empty())
824 __ret = end();
825 else
826 {
827 __glibcxx_assert(get_allocator() == __nh.get_allocator());
828
829 auto __code = this->_M_hash_code(__nh._M_key());
830 auto __node = std::exchange(__nh._M_ptr, nullptr);
831 // FIXME: this deallocates the node on exception.
832 __ret = _M_insert_multi_node(__hint._M_cur, __code, __node);
833 }
834 return __ret;
835 }
836
837 /// Extract a node.
838 node_type
839 extract(const_iterator __pos)
840 {
841 __node_type* __n = __pos._M_cur;
842 size_t __bkt = _M_bucket_index(__n);
843
844 // Look for previous node to unlink it from the erased one, this
845 // is why we need buckets to contain the before begin to make
846 // this search fast.
847 __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
848
849 if (__prev_n == _M_buckets[__bkt])
850 _M_remove_bucket_begin(__bkt, __n->_M_next(),
851 __n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
852 else if (__n->_M_nxt)
853 {
854 size_type __next_bkt = _M_bucket_index(__n->_M_next());
855 if (__next_bkt != __bkt)
856 _M_buckets[__next_bkt] = __prev_n;
857 }
858
859 __prev_n->_M_nxt = __n->_M_nxt;
860 __n->_M_nxt = nullptr;
861 --_M_element_count;
862 return { __n, this->_M_node_allocator() };
863 }
864
865 /// Extract a node.
866 node_type
867 extract(const _Key& __k)
868 {
869 node_type __nh;
870 auto __pos = find(__k);
871 if (__pos != end())
872 __nh = extract(const_iterator(__pos));
873 return __nh;
874 }
875
876 /// Merge from a compatible container into one with unique keys.
877 template<typename _Compatible_Hashtable>
878 void
879 _M_merge_unique(_Compatible_Hashtable& __src) noexcept
880 {
881 static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
882 node_type>, "Node types are compatible");
883 __glibcxx_assert(get_allocator() == __src.get_allocator());
884
885 auto __n_elt = __src.size();
886 for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
887 {
888 auto __pos = __i++;
889 const key_type& __k = this->_M_extract()(__pos._M_cur->_M_v());
890 __hash_code __code = this->_M_hash_code(__k);
891 size_type __bkt = _M_bucket_index(__k, __code);
892 if (_M_find_node(__bkt, __k, __code) == nullptr)
893 {
894 auto __nh = __src.extract(__pos);
895 _M_insert_unique_node(__bkt, __code, __nh._M_ptr, __n_elt);
896 __nh._M_ptr = nullptr;
897 __n_elt = 1;
898 }
899 else if (__n_elt != 1)
900 --__n_elt;
901 }
902 }
903
904 /// Merge from a compatible container into one with equivalent keys.
905 template<typename _Compatible_Hashtable>
906 void
907 _M_merge_multi(_Compatible_Hashtable& __src) noexcept
908 {
909 static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
910 node_type>, "Node types are compatible");
911 __glibcxx_assert(get_allocator() == __src.get_allocator());
912
913 this->reserve(size() + __src.size());
914 for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
915 _M_reinsert_node_multi(cend(), __src.extract(__i++));
916 }
917#endif // C++17
918
919 private:
920 // Helper rehash method used when keys are unique.
921 void _M_rehash_aux(size_type __n, std::true_type);
922
923 // Helper rehash method used when keys can be non-unique.
924 void _M_rehash_aux(size_type __n, std::false_type);
925
926 // Unconditionally change size of bucket array to n, restore
927 // hash policy state to __state on exception.
928 void _M_rehash(size_type __n, const __rehash_state& __state);
929 };
930
931
932 // Definitions of class template _Hashtable's out-of-line member functions.
933 template<typename _Key, typename _Value,
934 typename _Alloc, typename _ExtractKey, typename _Equal,
935 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
936 typename _Traits>
937 auto
938 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
939 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
940 _M_bucket_begin(size_type __bkt) const
941 -> __node_type*
942 {
943 __node_base* __n = _M_buckets[__bkt];
944 return __n ? static_cast<__node_type*>(__n->_M_nxt) : nullptr;
945 }
946
947 template<typename _Key, typename _Value,
948 typename _Alloc, typename _ExtractKey, typename _Equal,
949 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
950 typename _Traits>
951 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
952 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
953 _Hashtable(size_type __bucket_hint,
954 const _H1& __h1, const _H2& __h2, const _Hash& __h,
955 const _Equal& __eq, const _ExtractKey& __exk,
956 const allocator_type& __a)
957 : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
958 {
959 auto __bkt = _M_rehash_policy._M_next_bkt(__bucket_hint);
960 if (__bkt > _M_bucket_count)
961 {
962 _M_buckets = _M_allocate_buckets(__bkt);
963 _M_bucket_count = __bkt;
964 }
965 }
966
967 template<typename _Key, typename _Value,
968 typename _Alloc, typename _ExtractKey, typename _Equal,
969 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
970 typename _Traits>
971 template<typename _InputIterator>
972 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
973 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
974 _Hashtable(_InputIterator __f, _InputIterator __l,
975 size_type __bucket_hint,
976 const _H1& __h1, const _H2& __h2, const _Hash& __h,
977 const _Equal& __eq, const _ExtractKey& __exk,
978 const allocator_type& __a)
979 : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
980 {
981 auto __nb_elems = __detail::__distance_fw(__f, __l);
982 auto __bkt_count =
983 _M_rehash_policy._M_next_bkt(
984 std::max(_M_rehash_policy._M_bkt_for_elements(__nb_elems),
985 __bucket_hint));
986
987 if (__bkt_count > _M_bucket_count)
988 {
989 _M_buckets = _M_allocate_buckets(__bkt_count);
990 _M_bucket_count = __bkt_count;
991 }
992
993 for (; __f != __l; ++__f)
994 this->insert(*__f);
995 }
996
997 template<typename _Key, typename _Value,
998 typename _Alloc, typename _ExtractKey, typename _Equal,
999 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1000 typename _Traits>
1001 auto
1002 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1003 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1004 operator=(const _Hashtable& __ht)
1005 -> _Hashtable&
1006 {
1007 if (&__ht == this)
1008 return *this;
1009
1010 if (__node_alloc_traits::_S_propagate_on_copy_assign())
1011 {
1012 auto& __this_alloc = this->_M_node_allocator();
1013 auto& __that_alloc = __ht._M_node_allocator();
1014 if (!__node_alloc_traits::_S_always_equal()
1015 && __this_alloc != __that_alloc)
1016 {
1017 // Replacement allocator cannot free existing storage.
1018 this->_M_deallocate_nodes(_M_begin());
1019 _M_before_begin._M_nxt = nullptr;
1020 _M_deallocate_buckets();
1021 _M_buckets = nullptr;
1022 std::__alloc_on_copy(__this_alloc, __that_alloc);
1023 __hashtable_base::operator=(__ht);
1024 _M_bucket_count = __ht._M_bucket_count;
1025 _M_element_count = __ht._M_element_count;
1026 _M_rehash_policy = __ht._M_rehash_policy;
1027 __try
1028 {
1029 _M_assign(__ht,
1030 [this](const __node_type* __n)
1031 { return this->_M_allocate_node(__n->_M_v()); });
1032 }
1033 __catch(...)
1034 {
1035 // _M_assign took care of deallocating all memory. Now we
1036 // must make sure this instance remains in a usable state.
1037 _M_reset();
1038 __throw_exception_again;
1039 }
1040 return *this;
1041 }
1042 std::__alloc_on_copy(__this_alloc, __that_alloc);
1043 }
1044
1045 // Reuse allocated buckets and nodes.
1046 _M_assign_elements(__ht,
1047 [](const __reuse_or_alloc_node_type& __roan, const __node_type* __n)
1048 { return __roan(__n->_M_v()); });
1049 return *this;
1050 }
1051
1052 template<typename _Key, typename _Value,
1053 typename _Alloc, typename _ExtractKey, typename _Equal,
1054 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1055 typename _Traits>
1056 template<typename _Ht, typename _NodeGenerator>
1057 void
1058 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1059 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1060 _M_assign_elements(_Ht&& __ht, const _NodeGenerator& __node_gen)
1061 {
1062 __bucket_type* __former_buckets = nullptr;
1063 std::size_t __former_bucket_count = _M_bucket_count;
1064 const __rehash_state& __former_state = _M_rehash_policy._M_state();
1065
1066 if (_M_bucket_count != __ht._M_bucket_count)
1067 {
1068 __former_buckets = _M_buckets;
1069 _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
1070 _M_bucket_count = __ht._M_bucket_count;
1071 }
1072 else
1073 __builtin_memset(_M_buckets, 0,
1074 _M_bucket_count * sizeof(__bucket_type));
1075
1076 __try
1077 {
1078 __hashtable_base::operator=(std::forward<_Ht>(__ht));
1079 _M_element_count = __ht._M_element_count;
1080 _M_rehash_policy = __ht._M_rehash_policy;
1081 __reuse_or_alloc_node_type __roan(_M_begin(), *this);
1082 _M_before_begin._M_nxt = nullptr;
1083 _M_assign(__ht,
1084 [&__node_gen, &__roan](__node_type* __n)
1085 { return __node_gen(__roan, __n); });
1086 if (__former_buckets)
1087 _M_deallocate_buckets(__former_buckets, __former_bucket_count);
1088 }
1089 __catch(...)
1090 {
1091 if (__former_buckets)
1092 {
1093 // Restore previous buckets.
1094 _M_deallocate_buckets();
1095 _M_rehash_policy._M_reset(__former_state);
1096 _M_buckets = __former_buckets;
1097 _M_bucket_count = __former_bucket_count;
1098 }
1099 __builtin_memset(_M_buckets, 0,
1100 _M_bucket_count * sizeof(__bucket_type));
1101 __throw_exception_again;
1102 }
1103 }
1104
1105 template<typename _Key, typename _Value,
1106 typename _Alloc, typename _ExtractKey, typename _Equal,
1107 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1108 typename _Traits>
1109 template<typename _NodeGenerator>
1110 void
1111 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1112 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1113 _M_assign(const _Hashtable& __ht, const _NodeGenerator& __node_gen)
1114 {
1115 __bucket_type* __buckets = nullptr;
1116 if (!_M_buckets)
1117 _M_buckets = __buckets = _M_allocate_buckets(_M_bucket_count);
1118
1119 __try
1120 {
1121 if (!__ht._M_before_begin._M_nxt)
1122 return;
1123
1124 // First deal with the special first node pointed to by
1125 // _M_before_begin.
1126 __node_type* __ht_n = __ht._M_begin();
1127 __node_type* __this_n = __node_gen(__ht_n);
1128 this->_M_copy_code(__this_n, __ht_n);
1129 _M_before_begin._M_nxt = __this_n;
1130 _M_buckets[_M_bucket_index(__this_n)] = &_M_before_begin;
1131
1132 // Then deal with other nodes.
1133 __node_base* __prev_n = __this_n;
1134 for (__ht_n = __ht_n->_M_next(); __ht_n; __ht_n = __ht_n->_M_next())
1135 {
1136 __this_n = __node_gen(__ht_n);
1137 __prev_n->_M_nxt = __this_n;
1138 this->_M_copy_code(__this_n, __ht_n);
1139 size_type __bkt = _M_bucket_index(__this_n);
1140 if (!_M_buckets[__bkt])
1141 _M_buckets[__bkt] = __prev_n;
1142 __prev_n = __this_n;
1143 }
1144 }
1145 __catch(...)
1146 {
1147 clear();
1148 if (__buckets)
1149 _M_deallocate_buckets();
1150 __throw_exception_again;
1151 }
1152 }
1153
1154 template<typename _Key, typename _Value,
1155 typename _Alloc, typename _ExtractKey, typename _Equal,
1156 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1157 typename _Traits>
1158 void
1159 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1160 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1161 _M_reset() noexcept
1162 {
1163 _M_rehash_policy._M_reset();
1164 _M_bucket_count = 1;
1165 _M_single_bucket = nullptr;
1166 _M_buckets = &_M_single_bucket;
1167 _M_before_begin._M_nxt = nullptr;
1168 _M_element_count = 0;
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::true_type)
1179 {
1180 this->_M_deallocate_nodes(_M_begin());
1181 _M_deallocate_buckets();
1182 __hashtable_base::operator=(std::move(__ht));
1183 _M_rehash_policy = __ht._M_rehash_policy;
1184 if (!__ht._M_uses_single_bucket())
1185 _M_buckets = __ht._M_buckets;
1186 else
1187 {
1188 _M_buckets = &_M_single_bucket;
1189 _M_single_bucket = __ht._M_single_bucket;
1190 }
1191 _M_bucket_count = __ht._M_bucket_count;
1192 _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
1193 _M_element_count = __ht._M_element_count;
1194 std::__alloc_on_move(this->_M_node_allocator(), __ht._M_node_allocator());
1195
1196 // Fix buckets containing the _M_before_begin pointers that can't be
1197 // moved.
1198 if (_M_begin())
1199 _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1200 __ht._M_reset();
1201 }
1202
1203 template<typename _Key, typename _Value,
1204 typename _Alloc, typename _ExtractKey, typename _Equal,
1205 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1206 typename _Traits>
1207 void
1208 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1209 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1210 _M_move_assign(_Hashtable&& __ht, std::false_type)
1211 {
1212 if (__ht._M_node_allocator() == this->_M_node_allocator())
1213 _M_move_assign(std::move(__ht), std::true_type());
1214 else
1215 {
1216 // Can't move memory, move elements then.
1217 _M_assign_elements(std::move(__ht),
1218 [](const __reuse_or_alloc_node_type& __roan, __node_type* __n)
1219 { return __roan(std::move_if_noexcept(__n->_M_v())); });
1220 __ht.clear();
1221 }
1222 }
1223
1224 template<typename _Key, typename _Value,
1225 typename _Alloc, typename _ExtractKey, typename _Equal,
1226 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1227 typename _Traits>
1228 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1229 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1230 _Hashtable(const _Hashtable& __ht)
1231 : __hashtable_base(__ht),
1232 __map_base(__ht),
1233 __rehash_base(__ht),
1234 __hashtable_alloc(
1235 __node_alloc_traits::_S_select_on_copy(__ht._M_node_allocator())),
1236 _M_buckets(nullptr),
1237 _M_bucket_count(__ht._M_bucket_count),
1238 _M_element_count(__ht._M_element_count),
1239 _M_rehash_policy(__ht._M_rehash_policy)
1240 {
1241 _M_assign(__ht,
1242 [this](const __node_type* __n)
1243 { return this->_M_allocate_node(__n->_M_v()); });
1244 }
1245
1246 template<typename _Key, typename _Value,
1247 typename _Alloc, typename _ExtractKey, typename _Equal,
1248 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1249 typename _Traits>
1250 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1251 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1252 _Hashtable(_Hashtable&& __ht) noexcept
1253 : __hashtable_base(__ht),
1254 __map_base(__ht),
1255 __rehash_base(__ht),
1256 __hashtable_alloc(std::move(__ht._M_base_alloc())),
1257 _M_buckets(__ht._M_buckets),
1258 _M_bucket_count(__ht._M_bucket_count),
1259 _M_before_begin(__ht._M_before_begin._M_nxt),
1260 _M_element_count(__ht._M_element_count),
1261 _M_rehash_policy(__ht._M_rehash_policy)
1262 {
1263 // Update, if necessary, buckets if __ht is using its single bucket.
1264 if (__ht._M_uses_single_bucket())
1265 {
1266 _M_buckets = &_M_single_bucket;
1267 _M_single_bucket = __ht._M_single_bucket;
1268 }
1269
1270 // Update, if necessary, bucket pointing to before begin that hasn't
1271 // moved.
1272 if (_M_begin())
1273 _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1274
1275 __ht._M_reset();
1276 }
1277
1278 template<typename _Key, typename _Value,
1279 typename _Alloc, typename _ExtractKey, typename _Equal,
1280 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1281 typename _Traits>
1282 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1283 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1284 _Hashtable(const _Hashtable& __ht, const allocator_type& __a)
1285 : __hashtable_base(__ht),
1286 __map_base(__ht),
1287 __rehash_base(__ht),
1288 __hashtable_alloc(__node_alloc_type(__a)),
1289 _M_buckets(),
1290 _M_bucket_count(__ht._M_bucket_count),
1291 _M_element_count(__ht._M_element_count),
1292 _M_rehash_policy(__ht._M_rehash_policy)
1293 {
1294 _M_assign(__ht,
1295 [this](const __node_type* __n)
1296 { return this->_M_allocate_node(__n->_M_v()); });
1297 }
1298
1299 template<typename _Key, typename _Value,
1300 typename _Alloc, typename _ExtractKey, typename _Equal,
1301 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1302 typename _Traits>
1303 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1304 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1305 _Hashtable(_Hashtable&& __ht, const allocator_type& __a)
1306 : __hashtable_base(__ht),
1307 __map_base(__ht),
1308 __rehash_base(__ht),
1309 __hashtable_alloc(__node_alloc_type(__a)),
1310 _M_buckets(nullptr),
1311 _M_bucket_count(__ht._M_bucket_count),
1312 _M_element_count(__ht._M_element_count),
1313 _M_rehash_policy(__ht._M_rehash_policy)
1314 {
1315 if (__ht._M_node_allocator() == this->_M_node_allocator())
1316 {
1317 if (__ht._M_uses_single_bucket())
1318 {
1319 _M_buckets = &_M_single_bucket;
1320 _M_single_bucket = __ht._M_single_bucket;
1321 }
1322 else
1323 _M_buckets = __ht._M_buckets;
1324
1325 _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
1326 // Update, if necessary, bucket pointing to before begin that hasn't
1327 // moved.
1328 if (_M_begin())
1329 _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1330 __ht._M_reset();
1331 }
1332 else
1333 {
1334 _M_assign(__ht,
1335 [this](__node_type* __n)
1336 {
1337 return this->_M_allocate_node(
1338 std::move_if_noexcept(__n->_M_v()));
1339 });
1340 __ht.clear();
1341 }
1342 }
1343
1344 template<typename _Key, typename _Value,
1345 typename _Alloc, typename _ExtractKey, typename _Equal,
1346 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1347 typename _Traits>
1348 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1349 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1350 ~_Hashtable() noexcept
1351 {
1352 clear();
1353 _M_deallocate_buckets();
1354 }
1355
1356 template<typename _Key, typename _Value,
1357 typename _Alloc, typename _ExtractKey, typename _Equal,
1358 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1359 typename _Traits>
1360 void
1361 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1362 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1363 swap(_Hashtable& __x)
1364 noexcept(__and_<__is_nothrow_swappable<_H1>,
1365 __is_nothrow_swappable<_Equal>>::value)
1366 {
1367 // The only base class with member variables is hash_code_base.
1368 // We define _Hash_code_base::_M_swap because different
1369 // specializations have different members.
1370 this->_M_swap(__x);
1371
1372 std::__alloc_on_swap(this->_M_node_allocator(), __x._M_node_allocator());
1373 std::swap(_M_rehash_policy, __x._M_rehash_policy);
1374
1375 // Deal properly with potentially moved instances.
1376 if (this->_M_uses_single_bucket())
1377 {
1378 if (!__x._M_uses_single_bucket())
1379 {
1380 _M_buckets = __x._M_buckets;
1381 __x._M_buckets = &__x._M_single_bucket;
1382 }
1383 }
1384 else if (__x._M_uses_single_bucket())
1385 {
1386 __x._M_buckets = _M_buckets;
1387 _M_buckets = &_M_single_bucket;
1388 }
1389 else
1390 std::swap(_M_buckets, __x._M_buckets);
1391
1392 std::swap(_M_bucket_count, __x._M_bucket_count);
1393 std::swap(_M_before_begin._M_nxt, __x._M_before_begin._M_nxt);
1394 std::swap(_M_element_count, __x._M_element_count);
1395 std::swap(_M_single_bucket, __x._M_single_bucket);
1396
1397 // Fix buckets containing the _M_before_begin pointers that can't be
1398 // swapped.
1399 if (_M_begin())
1400 _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1401
1402 if (__x._M_begin())
1403 __x._M_buckets[__x._M_bucket_index(__x._M_begin())]
1404 = &__x._M_before_begin;
1405 }
1406
1407 template<typename _Key, typename _Value,
1408 typename _Alloc, typename _ExtractKey, typename _Equal,
1409 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1410 typename _Traits>
1411 auto
1412 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1413 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1414 find(const key_type& __k)
1415 -> iterator
1416 {
1417 __hash_code __code = this->_M_hash_code(__k);
1418 std::size_t __n = _M_bucket_index(__k, __code);
1419 __node_type* __p = _M_find_node(__n, __k, __code);
1420 return __p ? iterator(__p) : end();
1421 }
1422
1423 template<typename _Key, typename _Value,
1424 typename _Alloc, typename _ExtractKey, typename _Equal,
1425 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1426 typename _Traits>
1427 auto
1428 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1429 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1430 find(const key_type& __k) const
1431 -> const_iterator
1432 {
1433 __hash_code __code = this->_M_hash_code(__k);
1434 std::size_t __n = _M_bucket_index(__k, __code);
1435 __node_type* __p = _M_find_node(__n, __k, __code);
1436 return __p ? const_iterator(__p) : end();
1437 }
1438
1439 template<typename _Key, typename _Value,
1440 typename _Alloc, typename _ExtractKey, typename _Equal,
1441 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1442 typename _Traits>
1443 auto
1444 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1445 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1446 count(const key_type& __k) const
1447 -> size_type
1448 {
1449 __hash_code __code = this->_M_hash_code(__k);
1450 std::size_t __n = _M_bucket_index(__k, __code);
1451 __node_type* __p = _M_bucket_begin(__n);
1452 if (!__p)
1453 return 0;
1454
1455 std::size_t __result = 0;
1456 for (;; __p = __p->_M_next())
1457 {
1458 if (this->_M_equals(__k, __code, __p))
1459 ++__result;
1460 else if (__result)
1461 // All equivalent values are next to each other, if we
1462 // found a non-equivalent value after an equivalent one it
1463 // means that we won't find any new equivalent value.
1464 break;
1465 if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
1466 break;
1467 }
1468 return __result;
1469 }
1470
1471 template<typename _Key, typename _Value,
1472 typename _Alloc, typename _ExtractKey, typename _Equal,
1473 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1474 typename _Traits>
1475 auto
1476 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1477 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1478 equal_range(const key_type& __k)
1479 -> pair<iterator, iterator>
1480 {
1481 __hash_code __code = this->_M_hash_code(__k);
1482 std::size_t __n = _M_bucket_index(__k, __code);
1483 __node_type* __p = _M_find_node(__n, __k, __code);
1484
1485 if (__p)
1486 {
1487 __node_type* __p1 = __p->_M_next();
1488 while (__p1 && _M_bucket_index(__p1) == __n
1489 && this->_M_equals(__k, __code, __p1))
1490 __p1 = __p1->_M_next();
1491
1492 return std::make_pair(iterator(__p), iterator(__p1));
1493 }
1494 else
1495 return std::make_pair(end(), end());
1496 }
1497
1498 template<typename _Key, typename _Value,
1499 typename _Alloc, typename _ExtractKey, typename _Equal,
1500 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1501 typename _Traits>
1502 auto
1503 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1504 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1505 equal_range(const key_type& __k) const
1506 -> pair<const_iterator, const_iterator>
1507 {
1508 __hash_code __code = this->_M_hash_code(__k);
1509 std::size_t __n = _M_bucket_index(__k, __code);
1510 __node_type* __p = _M_find_node(__n, __k, __code);
1511
1512 if (__p)
1513 {
1514 __node_type* __p1 = __p->_M_next();
1515 while (__p1 && _M_bucket_index(__p1) == __n
1516 && this->_M_equals(__k, __code, __p1))
1517 __p1 = __p1->_M_next();
1518
1519 return std::make_pair(const_iterator(__p), const_iterator(__p1));
1520 }
1521 else
1522 return std::make_pair(end(), end());
1523 }
1524
1525 // Find the node whose key compares equal to k in the bucket n.
1526 // Return nullptr if no node is found.
1527 template<typename _Key, typename _Value,
1528 typename _Alloc, typename _ExtractKey, typename _Equal,
1529 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1530 typename _Traits>
1531 auto
1532 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1533 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1534 _M_find_before_node(size_type __n, const key_type& __k,
1535 __hash_code __code) const
1536 -> __node_base*
1537 {
1538 __node_base* __prev_p = _M_buckets[__n];
1539 if (!__prev_p)
1540 return nullptr;
1541
1542 for (__node_type* __p = static_cast<__node_type*>(__prev_p->_M_nxt);;
1543 __p = __p->_M_next())
1544 {
1545 if (this->_M_equals(__k, __code, __p))
1546 return __prev_p;
1547
1548 if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
1549 break;
1550 __prev_p = __p;
1551 }
1552 return nullptr;
1553 }
1554
1555 template<typename _Key, typename _Value,
1556 typename _Alloc, typename _ExtractKey, typename _Equal,
1557 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1558 typename _Traits>
1559 void
1560 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1561 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1562 _M_insert_bucket_begin(size_type __bkt, __node_type* __node)
1563 {
1564 if (_M_buckets[__bkt])
1565 {
1566 // Bucket is not empty, we just need to insert the new node
1567 // after the bucket before begin.
1568 __node->_M_nxt = _M_buckets[__bkt]->_M_nxt;
1569 _M_buckets[__bkt]->_M_nxt = __node;
1570 }
1571 else
1572 {
1573 // The bucket is empty, the new node is inserted at the
1574 // beginning of the singly-linked list and the bucket will
1575 // contain _M_before_begin pointer.
1576 __node->_M_nxt = _M_before_begin._M_nxt;
1577 _M_before_begin._M_nxt = __node;
1578 if (__node->_M_nxt)
1579 // We must update former begin bucket that is pointing to
1580 // _M_before_begin.
1581 _M_buckets[_M_bucket_index(__node->_M_next())] = __node;
1582 _M_buckets[__bkt] = &_M_before_begin;
1583 }
1584 }
1585
1586 template<typename _Key, typename _Value,
1587 typename _Alloc, typename _ExtractKey, typename _Equal,
1588 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1589 typename _Traits>
1590 void
1591 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1592 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1593 _M_remove_bucket_begin(size_type __bkt, __node_type* __next,
1594 size_type __next_bkt)
1595 {
1596 if (!__next || __next_bkt != __bkt)
1597 {
1598 // Bucket is now empty
1599 // First update next bucket if any
1600 if (__next)
1601 _M_buckets[__next_bkt] = _M_buckets[__bkt];
1602
1603 // Second update before begin node if necessary
1604 if (&_M_before_begin == _M_buckets[__bkt])
1605 _M_before_begin._M_nxt = __next;
1606 _M_buckets[__bkt] = nullptr;
1607 }
1608 }
1609
1610 template<typename _Key, typename _Value,
1611 typename _Alloc, typename _ExtractKey, typename _Equal,
1612 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1613 typename _Traits>
1614 auto
1615 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1616 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1617 _M_get_previous_node(size_type __bkt, __node_base* __n)
1618 -> __node_base*
1619 {
1620 __node_base* __prev_n = _M_buckets[__bkt];
1621 while (__prev_n->_M_nxt != __n)
1622 __prev_n = __prev_n->_M_nxt;
1623 return __prev_n;
1624 }
1625
1626 template<typename _Key, typename _Value,
1627 typename _Alloc, typename _ExtractKey, typename _Equal,
1628 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1629 typename _Traits>
1630 template<typename... _Args>
1631 auto
1632 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1633 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1634 _M_emplace(std::true_type, _Args&&... __args)
1635 -> pair<iterator, bool>
1636 {
1637 // First build the node to get access to the hash code
1638 __node_type* __node = this->_M_allocate_node(std::forward<_Args>(__args)...);
1639 const key_type& __k = this->_M_extract()(__node->_M_v());
1640 __hash_code __code;
1641 __try
1642 {
1643 __code = this->_M_hash_code(__k);
1644 }
1645 __catch(...)
1646 {
1647 this->_M_deallocate_node(__node);
1648 __throw_exception_again;
1649 }
1650
1651 size_type __bkt = _M_bucket_index(__k, __code);
1652 if (__node_type* __p = _M_find_node(__bkt, __k, __code))
1653 {
1654 // There is already an equivalent node, no insertion
1655 this->_M_deallocate_node(__node);
1656 return std::make_pair(iterator(__p), false);
1657 }
1658
1659 // Insert the node
1660 return std::make_pair(_M_insert_unique_node(__bkt, __code, __node),
1661 true);
1662 }
1663
1664 template<typename _Key, typename _Value,
1665 typename _Alloc, typename _ExtractKey, typename _Equal,
1666 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1667 typename _Traits>
1668 template<typename... _Args>
1669 auto
1670 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1671 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1672 _M_emplace(const_iterator __hint, std::false_type, _Args&&... __args)
1673 -> iterator
1674 {
1675 // First build the node to get its hash code.
1676 __node_type* __node =
1677 this->_M_allocate_node(std::forward<_Args>(__args)...);
1678
1679 __hash_code __code;
1680 __try
1681 {
1682 __code = this->_M_hash_code(this->_M_extract()(__node->_M_v()));
1683 }
1684 __catch(...)
1685 {
1686 this->_M_deallocate_node(__node);
1687 __throw_exception_again;
1688 }
1689
1690 return _M_insert_multi_node(__hint._M_cur, __code, __node);
1691 }
1692
1693 template<typename _Key, typename _Value,
1694 typename _Alloc, typename _ExtractKey, typename _Equal,
1695 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1696 typename _Traits>
1697 auto
1698 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1699 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1700 _M_insert_unique_node(size_type __bkt, __hash_code __code,
1701 __node_type* __node, size_type __n_elt)
1702 -> iterator
1703 {
1704 const __rehash_state& __saved_state = _M_rehash_policy._M_state();
1705 std::pair<bool, std::size_t> __do_rehash
1706 = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count,
1707 __n_elt);
1708
1709 __try
1710 {
1711 if (__do_rehash.first)
1712 {
1713 _M_rehash(__do_rehash.second, __saved_state);
1714 __bkt = _M_bucket_index(this->_M_extract()(__node->_M_v()), __code);
1715 }
1716
1717 this->_M_store_code(__node, __code);
1718
1719 // Always insert at the beginning of the bucket.
1720 _M_insert_bucket_begin(__bkt, __node);
1721 ++_M_element_count;
1722 return iterator(__node);
1723 }
1724 __catch(...)
1725 {
1726 this->_M_deallocate_node(__node);
1727 __throw_exception_again;
1728 }
1729 }
1730
1731 // Insert node, in bucket bkt if no rehash (assumes no element with its key
1732 // already present). Take ownership of the node, deallocate it on exception.
1733 template<typename _Key, typename _Value,
1734 typename _Alloc, typename _ExtractKey, typename _Equal,
1735 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1736 typename _Traits>
1737 auto
1738 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1739 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1740 _M_insert_multi_node(__node_type* __hint, __hash_code __code,
1741 __node_type* __node)
1742 -> iterator
1743 {
1744 const __rehash_state& __saved_state = _M_rehash_policy._M_state();
1745 std::pair<bool, std::size_t> __do_rehash
1746 = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count, 1);
1747
1748 __try
1749 {
1750 if (__do_rehash.first)
1751 _M_rehash(__do_rehash.second, __saved_state);
1752
1753 this->_M_store_code(__node, __code);
1754 const key_type& __k = this->_M_extract()(__node->_M_v());
1755 size_type __bkt = _M_bucket_index(__k, __code);
1756
1757 // Find the node before an equivalent one or use hint if it exists and
1758 // if it is equivalent.
1759 __node_base* __prev
1760 = __builtin_expect(__hint != nullptr, false)
1761 && this->_M_equals(__k, __code, __hint)
1762 ? __hint
1763 : _M_find_before_node(__bkt, __k, __code);
1764 if (__prev)
1765 {
1766 // Insert after the node before the equivalent one.
1767 __node->_M_nxt = __prev->_M_nxt;
1768 __prev->_M_nxt = __node;
1769 if (__builtin_expect(__prev == __hint, false))
1770 // hint might be the last bucket node, in this case we need to
1771 // update next bucket.
1772 if (__node->_M_nxt
1773 && !this->_M_equals(__k, __code, __node->_M_next()))
1774 {
1775 size_type __next_bkt = _M_bucket_index(__node->_M_next());
1776 if (__next_bkt != __bkt)
1777 _M_buckets[__next_bkt] = __node;
1778 }
1779 }
1780 else
1781 // The inserted node has no equivalent in the
1782 // hashtable. We must insert the new node at the
1783 // beginning of the bucket to preserve equivalent
1784 // elements' relative positions.
1785 _M_insert_bucket_begin(__bkt, __node);
1786 ++_M_element_count;
1787 return iterator(__node);
1788 }
1789 __catch(...)
1790 {
1791 this->_M_deallocate_node(__node);
1792 __throw_exception_again;
1793 }
1794 }
1795
1796 // Insert v if no element with its key is already present.
1797 template<typename _Key, typename _Value,
1798 typename _Alloc, typename _ExtractKey, typename _Equal,
1799 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1800 typename _Traits>
1801 template<typename _Arg, typename _NodeGenerator>
1802 auto
1803 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1804 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1805 _M_insert(_Arg&& __v, const _NodeGenerator& __node_gen, true_type,
1806 size_type __n_elt)
1807 -> pair<iterator, bool>
1808 {
1809 const key_type& __k = this->_M_extract()(__v);
1810 __hash_code __code = this->_M_hash_code(__k);
1811 size_type __bkt = _M_bucket_index(__k, __code);
1812
1813 __node_type* __n = _M_find_node(__bkt, __k, __code);
1814 if (__n)
1815 return std::make_pair(iterator(__n), false);
1816
1817 __n = __node_gen(std::forward<_Arg>(__v));
1818 return { _M_insert_unique_node(__bkt, __code, __n, __n_elt), true };
1819 }
1820
1821 // Insert v unconditionally.
1822 template<typename _Key, typename _Value,
1823 typename _Alloc, typename _ExtractKey, typename _Equal,
1824 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1825 typename _Traits>
1826 template<typename _Arg, typename _NodeGenerator>
1827 auto
1828 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1829 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1830 _M_insert(const_iterator __hint, _Arg&& __v,
1831 const _NodeGenerator& __node_gen, false_type)
1832 -> iterator
1833 {
1834 // First compute the hash code so that we don't do anything if it
1835 // throws.
1836 __hash_code __code = this->_M_hash_code(this->_M_extract()(__v));
1837
1838 // Second allocate new node so that we don't rehash if it throws.
1839 __node_type* __node = __node_gen(std::forward<_Arg>(__v));
1840
1841 return _M_insert_multi_node(__hint._M_cur, __code, __node);
1842 }
1843
1844 template<typename _Key, typename _Value,
1845 typename _Alloc, typename _ExtractKey, typename _Equal,
1846 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1847 typename _Traits>
1848 auto
1849 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1850 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1851 erase(const_iterator __it)
1852 -> iterator
1853 {
1854 __node_type* __n = __it._M_cur;
1855 std::size_t __bkt = _M_bucket_index(__n);
1856
1857 // Look for previous node to unlink it from the erased one, this
1858 // is why we need buckets to contain the before begin to make
1859 // this search fast.
1860 __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
1861 return _M_erase(__bkt, __prev_n, __n);
1862 }
1863
1864 template<typename _Key, typename _Value,
1865 typename _Alloc, typename _ExtractKey, typename _Equal,
1866 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1867 typename _Traits>
1868 auto
1869 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1870 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1871 _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n)
1872 -> iterator
1873 {
1874 if (__prev_n == _M_buckets[__bkt])
1875 _M_remove_bucket_begin(__bkt, __n->_M_next(),
1876 __n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
1877 else if (__n->_M_nxt)
1878 {
1879 size_type __next_bkt = _M_bucket_index(__n->_M_next());
1880 if (__next_bkt != __bkt)
1881 _M_buckets[__next_bkt] = __prev_n;
1882 }
1883
1884 __prev_n->_M_nxt = __n->_M_nxt;
1885 iterator __result(__n->_M_next());
1886 this->_M_deallocate_node(__n);
1887 --_M_element_count;
1888
1889 return __result;
1890 }
1891
1892 template<typename _Key, typename _Value,
1893 typename _Alloc, typename _ExtractKey, typename _Equal,
1894 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1895 typename _Traits>
1896 auto
1897 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1898 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1899 _M_erase(std::true_type, const key_type& __k)
1900 -> size_type
1901 {
1902 __hash_code __code = this->_M_hash_code(__k);
1903 std::size_t __bkt = _M_bucket_index(__k, __code);
1904
1905 // Look for the node before the first matching node.
1906 __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
1907 if (!__prev_n)
1908 return 0;
1909
1910 // We found a matching node, erase it.
1911 __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
1912 _M_erase(__bkt, __prev_n, __n);
1913 return 1;
1914 }
1915
1916 template<typename _Key, typename _Value,
1917 typename _Alloc, typename _ExtractKey, typename _Equal,
1918 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1919 typename _Traits>
1920 auto
1921 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1922 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1923 _M_erase(std::false_type, const key_type& __k)
1924 -> size_type
1925 {
1926 __hash_code __code = this->_M_hash_code(__k);
1927 std::size_t __bkt = _M_bucket_index(__k, __code);
1928
1929 // Look for the node before the first matching node.
1930 __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
1931 if (!__prev_n)
1932 return 0;
1933
1934 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1935 // 526. Is it undefined if a function in the standard changes
1936 // in parameters?
1937 // We use one loop to find all matching nodes and another to deallocate
1938 // them so that the key stays valid during the first loop. It might be
1939 // invalidated indirectly when destroying nodes.
1940 __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
1941 __node_type* __n_last = __n;
1942 std::size_t __n_last_bkt = __bkt;
1943 do
1944 {
1945 __n_last = __n_last->_M_next();
1946 if (!__n_last)
1947 break;
1948 __n_last_bkt = _M_bucket_index(__n_last);
1949 }
1950 while (__n_last_bkt == __bkt && this->_M_equals(__k, __code, __n_last));
1951
1952 // Deallocate nodes.
1953 size_type __result = 0;
1954 do
1955 {
1956 __node_type* __p = __n->_M_next();
1957 this->_M_deallocate_node(__n);
1958 __n = __p;
1959 ++__result;
1960 --_M_element_count;
1961 }
1962 while (__n != __n_last);
1963
1964 if (__prev_n == _M_buckets[__bkt])
1965 _M_remove_bucket_begin(__bkt, __n_last, __n_last_bkt);
1966 else if (__n_last && __n_last_bkt != __bkt)
1967 _M_buckets[__n_last_bkt] = __prev_n;
1968 __prev_n->_M_nxt = __n_last;
1969 return __result;
1970 }
1971
1972 template<typename _Key, typename _Value,
1973 typename _Alloc, typename _ExtractKey, typename _Equal,
1974 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1975 typename _Traits>
1976 auto
1977 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1978 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1979 erase(const_iterator __first, const_iterator __last)
1980 -> iterator
1981 {
1982 __node_type* __n = __first._M_cur;
1983 __node_type* __last_n = __last._M_cur;
1984 if (__n == __last_n)
1985 return iterator(__n);
1986
1987 std::size_t __bkt = _M_bucket_index(__n);
1988
1989 __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
1990 bool __is_bucket_begin = __n == _M_bucket_begin(__bkt);
1991 std::size_t __n_bkt = __bkt;
1992 for (;;)
1993 {
1994 do
1995 {
1996 __node_type* __tmp = __n;
1997 __n = __n->_M_next();
1998 this->_M_deallocate_node(__tmp);
1999 --_M_element_count;
2000 if (!__n)
2001 break;
2002 __n_bkt = _M_bucket_index(__n);
2003 }
2004 while (__n != __last_n && __n_bkt == __bkt);
2005 if (__is_bucket_begin)
2006 _M_remove_bucket_begin(__bkt, __n, __n_bkt);
2007 if (__n == __last_n)
2008 break;
2009 __is_bucket_begin = true;
2010 __bkt = __n_bkt;
2011 }
2012
2013 if (__n && (__n_bkt != __bkt || __is_bucket_begin))
2014 _M_buckets[__n_bkt] = __prev_n;
2015 __prev_n->_M_nxt = __n;
2016 return iterator(__n);
2017 }
2018
2019 template<typename _Key, typename _Value,
2020 typename _Alloc, typename _ExtractKey, typename _Equal,
2021 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2022 typename _Traits>
2023 void
2024 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2025 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2026 clear() noexcept
2027 {
2028 this->_M_deallocate_nodes(_M_begin());
2029 __builtin_memset(_M_buckets, 0, _M_bucket_count * sizeof(__bucket_type));
2030 _M_element_count = 0;
2031 _M_before_begin._M_nxt = nullptr;
2032 }
2033
2034 template<typename _Key, typename _Value,
2035 typename _Alloc, typename _ExtractKey, typename _Equal,
2036 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2037 typename _Traits>
2038 void
2039 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2040 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2041 rehash(size_type __n)
2042 {
2043 const __rehash_state& __saved_state = _M_rehash_policy._M_state();
2044 std::size_t __buckets
2045 = std::max(_M_rehash_policy._M_bkt_for_elements(_M_element_count + 1),
2046 __n);
2047 __buckets = _M_rehash_policy._M_next_bkt(__buckets);
2048
2049 if (__buckets != _M_bucket_count)
2050 _M_rehash(__buckets, __saved_state);
2051 else
2052 // No rehash, restore previous state to keep a consistent state.
2053 _M_rehash_policy._M_reset(__saved_state);
2054 }
2055
2056 template<typename _Key, typename _Value,
2057 typename _Alloc, typename _ExtractKey, typename _Equal,
2058 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2059 typename _Traits>
2060 void
2061 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2062 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2063 _M_rehash(size_type __n, const __rehash_state& __state)
2064 {
2065 __try
2066 {
2067 _M_rehash_aux(__n, __unique_keys());
2068 }
2069 __catch(...)
2070 {
2071 // A failure here means that buckets allocation failed. We only
2072 // have to restore hash policy previous state.
2073 _M_rehash_policy._M_reset(__state);
2074 __throw_exception_again;
2075 }
2076 }
2077
2078 // Rehash when there is no equivalent elements.
2079 template<typename _Key, typename _Value,
2080 typename _Alloc, typename _ExtractKey, typename _Equal,
2081 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2082 typename _Traits>
2083 void
2084 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2085 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2086 _M_rehash_aux(size_type __n, std::true_type)
2087 {
2088 __bucket_type* __new_buckets = _M_allocate_buckets(__n);
2089 __node_type* __p = _M_begin();
2090 _M_before_begin._M_nxt = nullptr;
2091 std::size_t __bbegin_bkt = 0;
2092 while (__p)
2093 {
2094 __node_type* __next = __p->_M_next();
2095 std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
2096 if (!__new_buckets[__bkt])
2097 {
2098 __p->_M_nxt = _M_before_begin._M_nxt;
2099 _M_before_begin._M_nxt = __p;
2100 __new_buckets[__bkt] = &_M_before_begin;
2101 if (__p->_M_nxt)
2102 __new_buckets[__bbegin_bkt] = __p;
2103 __bbegin_bkt = __bkt;
2104 }
2105 else
2106 {
2107 __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2108 __new_buckets[__bkt]->_M_nxt = __p;
2109 }
2110 __p = __next;
2111 }
2112
2113 _M_deallocate_buckets();
2114 _M_bucket_count = __n;
2115 _M_buckets = __new_buckets;
2116 }
2117
2118 // Rehash when there can be equivalent elements, preserve their relative
2119 // order.
2120 template<typename _Key, typename _Value,
2121 typename _Alloc, typename _ExtractKey, typename _Equal,
2122 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2123 typename _Traits>
2124 void
2125 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2126 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2127 _M_rehash_aux(size_type __n, std::false_type)
2128 {
2129 __bucket_type* __new_buckets = _M_allocate_buckets(__n);
2130
2131 __node_type* __p = _M_begin();
2132 _M_before_begin._M_nxt = nullptr;
2133 std::size_t __bbegin_bkt = 0;
2134 std::size_t __prev_bkt = 0;
2135 __node_type* __prev_p = nullptr;
2136 bool __check_bucket = false;
2137
2138 while (__p)
2139 {
2140 __node_type* __next = __p->_M_next();
2141 std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
2142
2143 if (__prev_p && __prev_bkt == __bkt)
2144 {
2145 // Previous insert was already in this bucket, we insert after
2146 // the previously inserted one to preserve equivalent elements
2147 // relative order.
2148 __p->_M_nxt = __prev_p->_M_nxt;
2149 __prev_p->_M_nxt = __p;
2150
2151 // Inserting after a node in a bucket require to check that we
2152 // haven't change the bucket last node, in this case next
2153 // bucket containing its before begin node must be updated. We
2154 // schedule a check as soon as we move out of the sequence of
2155 // equivalent nodes to limit the number of checks.
2156 __check_bucket = true;
2157 }
2158 else
2159 {
2160 if (__check_bucket)
2161 {
2162 // Check if we shall update the next bucket because of
2163 // insertions into __prev_bkt bucket.
2164 if (__prev_p->_M_nxt)
2165 {
2166 std::size_t __next_bkt
2167 = __hash_code_base::_M_bucket_index(__prev_p->_M_next(),
2168 __n);
2169 if (__next_bkt != __prev_bkt)
2170 __new_buckets[__next_bkt] = __prev_p;
2171 }
2172 __check_bucket = false;
2173 }
2174
2175 if (!__new_buckets[__bkt])
2176 {
2177 __p->_M_nxt = _M_before_begin._M_nxt;
2178 _M_before_begin._M_nxt = __p;
2179 __new_buckets[__bkt] = &_M_before_begin;
2180 if (__p->_M_nxt)
2181 __new_buckets[__bbegin_bkt] = __p;
2182 __bbegin_bkt = __bkt;
2183 }
2184 else
2185 {
2186 __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2187 __new_buckets[__bkt]->_M_nxt = __p;
2188 }
2189 }
2190 __prev_p = __p;
2191 __prev_bkt = __bkt;
2192 __p = __next;
2193 }
2194
2195 if (__check_bucket && __prev_p->_M_nxt)
2196 {
2197 std::size_t __next_bkt
2198 = __hash_code_base::_M_bucket_index(__prev_p->_M_next(), __n);
2199 if (__next_bkt != __prev_bkt)
2200 __new_buckets[__next_bkt] = __prev_p;
2201 }
2202
2203 _M_deallocate_buckets();
2204 _M_bucket_count = __n;
2205 _M_buckets = __new_buckets;
2206 }
2207
2208#if __cplusplus > 201402L
2209 template<typename, typename, typename> class _Hash_merge_helper { };
2210#endif // C++17
2211
2212#if __cpp_deduction_guides >= 201606
2213 // Used to constrain deduction guides
2214 template<typename _Hash>
2215 using _RequireNotAllocatorOrIntegral
2216 = __enable_if_t<!__or_<is_integral<_Hash>, __is_allocator<_Hash>>::value>;
2217#endif
2218
2219_GLIBCXX_END_NAMESPACE_VERSION
2220} // namespace std
2221
2222#endif // _HASHTABLE_H
2223