1 // hashtable.h header -*- C++ -*-
2
3 // Copyright (C) 2007-2018 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
_GLIBCXX_VISIBILITY(default)40 namespace 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 static_assert(__is_invocable<const _H1&, const _Key&>{},
196 "hash function must be invocable with an argument of key type");
197 static_assert(__is_invocable<const _Equal&, const _Key&, const _Key&>{},
198 "key equality predicate must be invocable with two arguments of "
199 "key type");
200
201 using __traits_type = _Traits;
202 using __hash_cached = typename __traits_type::__hash_cached;
203 using __node_type = __detail::_Hash_node<_Value, __hash_cached::value>;
204 using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>;
205
206 using __hashtable_alloc = __detail::_Hashtable_alloc<__node_alloc_type>;
207
208 using __value_alloc_traits =
209 typename __hashtable_alloc::__value_alloc_traits;
210 using __node_alloc_traits =
211 typename __hashtable_alloc::__node_alloc_traits;
212 using __node_base = typename __hashtable_alloc::__node_base;
213 using __bucket_type = typename __hashtable_alloc::__bucket_type;
214
215 public:
216 typedef _Key key_type;
217 typedef _Value value_type;
218 typedef _Alloc allocator_type;
219 typedef _Equal key_equal;
220
221 // mapped_type, if present, comes from _Map_base.
222 // hasher, if present, comes from _Hash_code_base/_Hashtable_base.
223 typedef typename __value_alloc_traits::pointer pointer;
224 typedef typename __value_alloc_traits::const_pointer const_pointer;
225 typedef value_type& reference;
226 typedef const value_type& const_reference;
227
228 private:
229 using __rehash_type = _RehashPolicy;
230 using __rehash_state = typename __rehash_type::_State;
231
232 using __constant_iterators = typename __traits_type::__constant_iterators;
233 using __unique_keys = typename __traits_type::__unique_keys;
234
235 using __key_extract = typename std::conditional<
236 __constant_iterators::value,
237 __detail::_Identity,
238 __detail::_Select1st>::type;
239
240 using __hashtable_base = __detail::
241 _Hashtable_base<_Key, _Value, _ExtractKey,
242 _Equal, _H1, _H2, _Hash, _Traits>;
243
244 using __hash_code_base = typename __hashtable_base::__hash_code_base;
245 using __hash_code = typename __hashtable_base::__hash_code;
246 using __ireturn_type = typename __hashtable_base::__ireturn_type;
247
248 using __map_base = __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey,
249 _Equal, _H1, _H2, _Hash,
250 _RehashPolicy, _Traits>;
251
252 using __rehash_base = __detail::_Rehash_base<_Key, _Value, _Alloc,
253 _ExtractKey, _Equal,
254 _H1, _H2, _Hash,
255 _RehashPolicy, _Traits>;
256
257 using __eq_base = __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey,
258 _Equal, _H1, _H2, _Hash,
259 _RehashPolicy, _Traits>;
260
261 using __reuse_or_alloc_node_type =
262 __detail::_ReuseOrAllocNode<__node_alloc_type>;
263
264 // Metaprogramming for picking apart hash caching.
265 template<typename _Cond>
266 using __if_hash_cached = __or_<__not_<__hash_cached>, _Cond>;
267
268 template<typename _Cond>
269 using __if_hash_not_cached = __or_<__hash_cached, _Cond>;
270
271 // Compile-time diagnostics.
272
273 // _Hash_code_base has everything protected, so use this derived type to
274 // access it.
275 struct __hash_code_base_access : __hash_code_base
276 { using __hash_code_base::_M_bucket_index; };
277
278 // Getting a bucket index from a node shall not throw because it is used
279 // in methods (erase, swap...) that shall not throw.
280 static_assert(noexcept(declval<const __hash_code_base_access&>()
281 ._M_bucket_index((const __node_type*)nullptr,
282 (std::size_t)0)),
283 "Cache the hash code or qualify your functors involved"
284 " in hash code and bucket index computation with noexcept");
285
286 // Following two static assertions are necessary to guarantee
287 // that local_iterator will be default constructible.
288
289 // When hash codes are cached local iterator inherits from H2 functor
290 // which must then be default constructible.
291 static_assert(__if_hash_cached<is_default_constructible<_H2>>::value,
292 "Functor used to map hash code to bucket index"
293 " must be default constructible");
294
295 template<typename _Keya, typename _Valuea, typename _Alloca,
296 typename _ExtractKeya, typename _Equala,
297 typename _H1a, typename _H2a, typename _Hasha,
298 typename _RehashPolicya, typename _Traitsa,
299 bool _Unique_keysa>
300 friend struct __detail::_Map_base;
301
302 template<typename _Keya, typename _Valuea, typename _Alloca,
303 typename _ExtractKeya, typename _Equala,
304 typename _H1a, typename _H2a, typename _Hasha,
305 typename _RehashPolicya, typename _Traitsa>
306 friend struct __detail::_Insert_base;
307
308 template<typename _Keya, typename _Valuea, typename _Alloca,
309 typename _ExtractKeya, typename _Equala,
310 typename _H1a, typename _H2a, typename _Hasha,
311 typename _RehashPolicya, typename _Traitsa,
312 bool _Constant_iteratorsa>
313 friend struct __detail::_Insert;
314
315 public:
316 using size_type = typename __hashtable_base::size_type;
317 using difference_type = typename __hashtable_base::difference_type;
318
319 using iterator = typename __hashtable_base::iterator;
320 using const_iterator = typename __hashtable_base::const_iterator;
321
322 using local_iterator = typename __hashtable_base::local_iterator;
323 using const_local_iterator = typename __hashtable_base::
324 const_local_iterator;
325
326 #if __cplusplus > 201402L
327 using node_type = _Node_handle<_Key, _Value, __node_alloc_type>;
328 using insert_return_type = _Node_insert_return<iterator, node_type>;
329 #endif
330
331 private:
332 __bucket_type* _M_buckets = &_M_single_bucket;
333 size_type _M_bucket_count = 1;
334 __node_base _M_before_begin;
335 size_type _M_element_count = 0;
336 _RehashPolicy _M_rehash_policy;
337
338 // A single bucket used when only need for 1 bucket. Especially
339 // interesting in move semantic to leave hashtable with only 1 buckets
340 // which is not allocated so that we can have those operations noexcept
341 // qualified.
342 // Note that we can't leave hashtable with 0 bucket without adding
343 // numerous checks in the code to avoid 0 modulus.
344 __bucket_type _M_single_bucket = nullptr;
345
346 bool
347 _M_uses_single_bucket(__bucket_type* __bkts) const
348 { return __builtin_expect(__bkts == &_M_single_bucket, false); }
349
350 bool
351 _M_uses_single_bucket() const
352 { return _M_uses_single_bucket(_M_buckets); }
353
354 __hashtable_alloc&
355 _M_base_alloc() { return *this; }
356
357 __bucket_type*
358 _M_allocate_buckets(size_type __n)
359 {
360 if (__builtin_expect(__n == 1, false))
361 {
362 _M_single_bucket = nullptr;
363 return &_M_single_bucket;
364 }
365
366 return __hashtable_alloc::_M_allocate_buckets(__n);
367 }
368
369 void
370 _M_deallocate_buckets(__bucket_type* __bkts, size_type __n)
371 {
372 if (_M_uses_single_bucket(__bkts))
373 return;
374
375 __hashtable_alloc::_M_deallocate_buckets(__bkts, __n);
376 }
377
378 void
379 _M_deallocate_buckets()
380 { _M_deallocate_buckets(_M_buckets, _M_bucket_count); }
381
382 // Gets bucket begin, deals with the fact that non-empty buckets contain
383 // their before begin node.
384 __node_type*
385 _M_bucket_begin(size_type __bkt) const;
386
387 __node_type*
388 _M_begin() const
389 { return static_cast<__node_type*>(_M_before_begin._M_nxt); }
390
391 template<typename _NodeGenerator>
392 void
393 _M_assign(const _Hashtable&, const _NodeGenerator&);
394
395 void
396 _M_move_assign(_Hashtable&&, std::true_type);
397
398 void
399 _M_move_assign(_Hashtable&&, std::false_type);
400
401 void
402 _M_reset() noexcept;
403
404 _Hashtable(const _H1& __h1, const _H2& __h2, const _Hash& __h,
405 const _Equal& __eq, const _ExtractKey& __exk,
406 const allocator_type& __a)
407 : __hashtable_base(__exk, __h1, __h2, __h, __eq),
408 __hashtable_alloc(__node_alloc_type(__a))
409 { }
410
411 public:
412 // Constructor, destructor, assignment, swap
413 _Hashtable() = default;
414 _Hashtable(size_type __bucket_hint,
415 const _H1&, const _H2&, const _Hash&,
416 const _Equal&, const _ExtractKey&,
417 const allocator_type&);
418
419 template<typename _InputIterator>
420 _Hashtable(_InputIterator __first, _InputIterator __last,
421 size_type __bucket_hint,
422 const _H1&, const _H2&, const _Hash&,
423 const _Equal&, const _ExtractKey&,
424 const allocator_type&);
425
426 _Hashtable(const _Hashtable&);
427
428 _Hashtable(_Hashtable&&) noexcept;
429
430 _Hashtable(const _Hashtable&, const allocator_type&);
431
432 _Hashtable(_Hashtable&&, const allocator_type&);
433
434 // Use delegating constructors.
435 explicit
436 _Hashtable(const allocator_type& __a)
437 : __hashtable_alloc(__node_alloc_type(__a))
438 { }
439
440 explicit
441 _Hashtable(size_type __n,
442 const _H1& __hf = _H1(),
443 const key_equal& __eql = key_equal(),
444 const allocator_type& __a = allocator_type())
445 : _Hashtable(__n, __hf, _H2(), _Hash(), __eql,
446 __key_extract(), __a)
447 { }
448
449 template<typename _InputIterator>
450 _Hashtable(_InputIterator __f, _InputIterator __l,
451 size_type __n = 0,
452 const _H1& __hf = _H1(),
453 const key_equal& __eql = key_equal(),
454 const allocator_type& __a = allocator_type())
455 : _Hashtable(__f, __l, __n, __hf, _H2(), _Hash(), __eql,
456 __key_extract(), __a)
457 { }
458
459 _Hashtable(initializer_list<value_type> __l,
460 size_type __n = 0,
461 const _H1& __hf = _H1(),
462 const key_equal& __eql = key_equal(),
463 const allocator_type& __a = allocator_type())
464 : _Hashtable(__l.begin(), __l.end(), __n, __hf, _H2(), _Hash(), __eql,
465 __key_extract(), __a)
466 { }
467
468 _Hashtable&
469 operator=(const _Hashtable& __ht);
470
471 _Hashtable&
472 operator=(_Hashtable&& __ht)
473 noexcept(__node_alloc_traits::_S_nothrow_move()
474 && is_nothrow_move_assignable<_H1>::value
475 && is_nothrow_move_assignable<_Equal>::value)
476 {
477 constexpr bool __move_storage =
478 __node_alloc_traits::_S_propagate_on_move_assign()
479 || __node_alloc_traits::_S_always_equal();
480 _M_move_assign(std::move(__ht), __bool_constant<__move_storage>());
481 return *this;
482 }
483
484 _Hashtable&
485 operator=(initializer_list<value_type> __l)
486 {
487 __reuse_or_alloc_node_type __roan(_M_begin(), *this);
488 _M_before_begin._M_nxt = nullptr;
489 clear();
490 this->_M_insert_range(__l.begin(), __l.end(), __roan, __unique_keys());
491 return *this;
492 }
493
494 ~_Hashtable() noexcept;
495
496 void
497 swap(_Hashtable&)
498 noexcept(__and_<__is_nothrow_swappable<_H1>,
499 __is_nothrow_swappable<_Equal>>::value);
500
501 // Basic container operations
502 iterator
503 begin() noexcept
504 { return iterator(_M_begin()); }
505
506 const_iterator
507 begin() const noexcept
508 { return const_iterator(_M_begin()); }
509
510 iterator
511 end() noexcept
512 { return iterator(nullptr); }
513
514 const_iterator
515 end() const noexcept
516 { return const_iterator(nullptr); }
517
518 const_iterator
519 cbegin() const noexcept
520 { return const_iterator(_M_begin()); }
521
522 const_iterator
523 cend() const noexcept
524 { return const_iterator(nullptr); }
525
526 size_type
527 size() const noexcept
528 { return _M_element_count; }
529
530 bool
531 empty() const noexcept
532 { return size() == 0; }
533
534 allocator_type
535 get_allocator() const noexcept
536 { return allocator_type(this->_M_node_allocator()); }
537
538 size_type
539 max_size() const noexcept
540 { return __node_alloc_traits::max_size(this->_M_node_allocator()); }
541
542 // Observers
543 key_equal
544 key_eq() const
545 { return this->_M_eq(); }
546
547 // hash_function, if present, comes from _Hash_code_base.
548
549 // Bucket operations
550 size_type
551 bucket_count() const noexcept
552 { return _M_bucket_count; }
553
554 size_type
555 max_bucket_count() const noexcept
556 { return max_size(); }
557
558 size_type
559 bucket_size(size_type __n) const
560 { return std::distance(begin(__n), end(__n)); }
561
562 size_type
563 bucket(const key_type& __k) const
564 { return _M_bucket_index(__k, this->_M_hash_code(__k)); }
565
566 local_iterator
567 begin(size_type __n)
568 {
569 return local_iterator(*this, _M_bucket_begin(__n),
570 __n, _M_bucket_count);
571 }
572
573 local_iterator
574 end(size_type __n)
575 { return local_iterator(*this, nullptr, __n, _M_bucket_count); }
576
577 const_local_iterator
578 begin(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 end(size_type __n) const
586 { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
587
588 // DR 691.
589 const_local_iterator
590 cbegin(size_type __n) const
591 {
592 return const_local_iterator(*this, _M_bucket_begin(__n),
593 __n, _M_bucket_count);
594 }
595
596 const_local_iterator
597 cend(size_type __n) const
598 { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
599
600 float
601 load_factor() const noexcept
602 {
603 return static_cast<float>(size()) / static_cast<float>(bucket_count());
604 }
605
606 // max_load_factor, if present, comes from _Rehash_base.
607
608 // Generalization of max_load_factor. Extension, not found in
609 // TR1. Only useful if _RehashPolicy is something other than
610 // the default.
611 const _RehashPolicy&
612 __rehash_policy() const
613 { return _M_rehash_policy; }
614
615 void
616 __rehash_policy(const _RehashPolicy& __pol)
617 { _M_rehash_policy = __pol; }
618
619 // Lookup.
620 iterator
621 find(const key_type& __k);
622
623 const_iterator
624 find(const key_type& __k) const;
625
626 size_type
627 count(const key_type& __k) const;
628
629 std::pair<iterator, iterator>
630 equal_range(const key_type& __k);
631
632 std::pair<const_iterator, const_iterator>
633 equal_range(const key_type& __k) const;
634
635 protected:
636 // Bucket index computation helpers.
637 size_type
638 _M_bucket_index(__node_type* __n) const noexcept
639 { return __hash_code_base::_M_bucket_index(__n, _M_bucket_count); }
640
641 size_type
642 _M_bucket_index(const key_type& __k, __hash_code __c) const
643 { return __hash_code_base::_M_bucket_index(__k, __c, _M_bucket_count); }
644
645 // Find and insert helper functions and types
646 // Find the node before the one matching the criteria.
647 __node_base*
648 _M_find_before_node(size_type, const key_type&, __hash_code) const;
649
650 __node_type*
651 _M_find_node(size_type __bkt, const key_type& __key,
652 __hash_code __c) const
653 {
654 __node_base* __before_n = _M_find_before_node(__bkt, __key, __c);
655 if (__before_n)
656 return static_cast<__node_type*>(__before_n->_M_nxt);
657 return nullptr;
658 }
659
660 // Insert a node at the beginning of a bucket.
661 void
662 _M_insert_bucket_begin(size_type, __node_type*);
663
664 // Remove the bucket first node
665 void
666 _M_remove_bucket_begin(size_type __bkt, __node_type* __next_n,
667 size_type __next_bkt);
668
669 // Get the node before __n in the bucket __bkt
670 __node_base*
671 _M_get_previous_node(size_type __bkt, __node_base* __n);
672
673 // Insert node with hash code __code, in bucket bkt if no rehash (assumes
674 // no element with its key already present). Take ownership of the node,
675 // deallocate it on exception.
676 iterator
677 _M_insert_unique_node(size_type __bkt, __hash_code __code,
678 __node_type* __n, size_type __n_elt = 1);
679
680 // Insert node with hash code __code. Take ownership of the node,
681 // deallocate it on exception.
682 iterator
683 _M_insert_multi_node(__node_type* __hint,
684 __hash_code __code, __node_type* __n);
685
686 template<typename... _Args>
687 std::pair<iterator, bool>
688 _M_emplace(std::true_type, _Args&&... __args);
689
690 template<typename... _Args>
691 iterator
692 _M_emplace(std::false_type __uk, _Args&&... __args)
693 { return _M_emplace(cend(), __uk, std::forward<_Args>(__args)...); }
694
695 // Emplace with hint, useless when keys are unique.
696 template<typename... _Args>
697 iterator
698 _M_emplace(const_iterator, std::true_type __uk, _Args&&... __args)
699 { return _M_emplace(__uk, std::forward<_Args>(__args)...).first; }
700
701 template<typename... _Args>
702 iterator
703 _M_emplace(const_iterator, std::false_type, _Args&&... __args);
704
705 template<typename _Arg, typename _NodeGenerator>
706 std::pair<iterator, bool>
707 _M_insert(_Arg&&, const _NodeGenerator&, true_type, size_type = 1);
708
709 template<typename _Arg, typename _NodeGenerator>
710 iterator
711 _M_insert(_Arg&& __arg, const _NodeGenerator& __node_gen,
712 false_type __uk)
713 {
714 return _M_insert(cend(), std::forward<_Arg>(__arg), __node_gen,
715 __uk);
716 }
717
718 // Insert with hint, not used when keys are unique.
719 template<typename _Arg, typename _NodeGenerator>
720 iterator
721 _M_insert(const_iterator, _Arg&& __arg,
722 const _NodeGenerator& __node_gen, true_type __uk)
723 {
724 return
725 _M_insert(std::forward<_Arg>(__arg), __node_gen, __uk).first;
726 }
727
728 // Insert with hint when keys are not unique.
729 template<typename _Arg, typename _NodeGenerator>
730 iterator
731 _M_insert(const_iterator, _Arg&&,
732 const _NodeGenerator&, false_type);
733
734 size_type
735 _M_erase(std::true_type, const key_type&);
736
737 size_type
738 _M_erase(std::false_type, const key_type&);
739
740 iterator
741 _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n);
742
743 public:
744 // Emplace
745 template<typename... _Args>
746 __ireturn_type
747 emplace(_Args&&... __args)
748 { return _M_emplace(__unique_keys(), std::forward<_Args>(__args)...); }
749
750 template<typename... _Args>
751 iterator
752 emplace_hint(const_iterator __hint, _Args&&... __args)
753 {
754 return _M_emplace(__hint, __unique_keys(),
755 std::forward<_Args>(__args)...);
756 }
757
758 // Insert member functions via inheritance.
759
760 // Erase
761 iterator
762 erase(const_iterator);
763
764 // LWG 2059.
765 iterator
766 erase(iterator __it)
767 { return erase(const_iterator(__it)); }
768
769 size_type
770 erase(const key_type& __k)
771 { return _M_erase(__unique_keys(), __k); }
772
773 iterator
774 erase(const_iterator, const_iterator);
775
776 void
777 clear() noexcept;
778
779 // Set number of buckets to be appropriate for container of n element.
780 void rehash(size_type __n);
781
782 // DR 1189.
783 // reserve, if present, comes from _Rehash_base.
784
785 #if __cplusplus > 201402L
786 /// Re-insert an extracted node into a container with unique keys.
787 insert_return_type
788 _M_reinsert_node(node_type&& __nh)
789 {
790 insert_return_type __ret;
791 if (__nh.empty())
792 __ret.position = end();
793 else
794 {
795 __glibcxx_assert(get_allocator() == __nh.get_allocator());
796
797 const key_type& __k = __nh._M_key();
798 __hash_code __code = this->_M_hash_code(__k);
799 size_type __bkt = _M_bucket_index(__k, __code);
800 if (__node_type* __n = _M_find_node(__bkt, __k, __code))
801 {
802 __ret.node = std::move(__nh);
803 __ret.position = iterator(__n);
804 __ret.inserted = false;
805 }
806 else
807 {
808 __ret.position
809 = _M_insert_unique_node(__bkt, __code, __nh._M_ptr);
810 __nh._M_ptr = nullptr;
811 __ret.inserted = true;
812 }
813 }
814 return __ret;
815 }
816
817 /// Re-insert an extracted node into a container with equivalent keys.
818 iterator
819 _M_reinsert_node_multi(const_iterator __hint, node_type&& __nh)
820 {
821 iterator __ret;
822 if (__nh.empty())
823 __ret = end();
824 else
825 {
826 __glibcxx_assert(get_allocator() == __nh.get_allocator());
827
828 auto __code = this->_M_hash_code(__nh._M_key());
829 auto __node = std::exchange(__nh._M_ptr, nullptr);
830 // FIXME: this deallocates the node on exception.
831 __ret = _M_insert_multi_node(__hint._M_cur, __code, __node);
832 }
833 return __ret;
834 }
835
836 /// Extract a node.
837 node_type
838 extract(const_iterator __pos)
839 {
840 __node_type* __n = __pos._M_cur;
841 size_t __bkt = _M_bucket_index(__n);
842
843 // Look for previous node to unlink it from the erased one, this
844 // is why we need buckets to contain the before begin to make
845 // this search fast.
846 __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
847
848 if (__prev_n == _M_buckets[__bkt])
849 _M_remove_bucket_begin(__bkt, __n->_M_next(),
850 __n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
851 else if (__n->_M_nxt)
852 {
853 size_type __next_bkt = _M_bucket_index(__n->_M_next());
854 if (__next_bkt != __bkt)
855 _M_buckets[__next_bkt] = __prev_n;
856 }
857
858 __prev_n->_M_nxt = __n->_M_nxt;
859 __n->_M_nxt = nullptr;
860 --_M_element_count;
861 return { __n, this->_M_node_allocator() };
862 }
863
864 /// Extract a node.
865 node_type
866 extract(const _Key& __k)
867 {
868 node_type __nh;
869 auto __pos = find(__k);
870 if (__pos != end())
871 __nh = extract(const_iterator(__pos));
872 return __nh;
873 }
874
875 /// Merge from a compatible container into one with unique keys.
876 template<typename _Compatible_Hashtable>
877 void
878 _M_merge_unique(_Compatible_Hashtable& __src) noexcept
879 {
880 static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
881 node_type>, "Node types are compatible");
882 __glibcxx_assert(get_allocator() == __src.get_allocator());
883
884 auto __n_elt = __src.size();
885 for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
886 {
887 auto __pos = __i++;
888 const key_type& __k = this->_M_extract()(__pos._M_cur->_M_v());
889 __hash_code __code = this->_M_hash_code(__k);
890 size_type __bkt = _M_bucket_index(__k, __code);
891 if (_M_find_node(__bkt, __k, __code) == nullptr)
892 {
893 auto __nh = __src.extract(__pos);
894 _M_insert_unique_node(__bkt, __code, __nh._M_ptr, __n_elt);
895 __nh._M_ptr = nullptr;
896 __n_elt = 1;
897 }
898 else if (__n_elt != 1)
899 --__n_elt;
900 }
901 }
902
903 /// Merge from a compatible container into one with equivalent keys.
904 template<typename _Compatible_Hashtable>
905 void
906 _M_merge_multi(_Compatible_Hashtable& __src) noexcept
907 {
908 static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
909 node_type>, "Node types are compatible");
910 __glibcxx_assert(get_allocator() == __src.get_allocator());
911
912 this->reserve(size() + __src.size());
913 for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
914 _M_reinsert_node_multi(cend(), __src.extract(__i++));
915 }
916 #endif // C++17
917
918 private:
919 // Helper rehash method used when keys are unique.
920 void _M_rehash_aux(size_type __n, std::true_type);
921
922 // Helper rehash method used when keys can be non-unique.
923 void _M_rehash_aux(size_type __n, std::false_type);
924
925 // Unconditionally change size of bucket array to n, restore
926 // hash policy state to __state on exception.
927 void _M_rehash(size_type __n, const __rehash_state& __state);
928 };
929
930
931 // Definitions of class template _Hashtable's out-of-line member functions.
932 template<typename _Key, typename _Value,
933 typename _Alloc, typename _ExtractKey, typename _Equal,
934 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
935 typename _Traits>
936 auto
937 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
938 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
939 _M_bucket_begin(size_type __bkt) const
940 -> __node_type*
941 {
942 __node_base* __n = _M_buckets[__bkt];
943 return __n ? static_cast<__node_type*>(__n->_M_nxt) : nullptr;
944 }
945
946 template<typename _Key, typename _Value,
947 typename _Alloc, typename _ExtractKey, typename _Equal,
948 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
949 typename _Traits>
950 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
951 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
952 _Hashtable(size_type __bucket_hint,
953 const _H1& __h1, const _H2& __h2, const _Hash& __h,
954 const _Equal& __eq, const _ExtractKey& __exk,
955 const allocator_type& __a)
956 : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
957 {
958 auto __bkt = _M_rehash_policy._M_next_bkt(__bucket_hint);
959 if (__bkt > _M_bucket_count)
960 {
961 _M_buckets = _M_allocate_buckets(__bkt);
962 _M_bucket_count = __bkt;
963 }
964 }
965
966 template<typename _Key, typename _Value,
967 typename _Alloc, typename _ExtractKey, typename _Equal,
968 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
969 typename _Traits>
970 template<typename _InputIterator>
971 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
972 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
973 _Hashtable(_InputIterator __f, _InputIterator __l,
974 size_type __bucket_hint,
975 const _H1& __h1, const _H2& __h2, const _Hash& __h,
976 const _Equal& __eq, const _ExtractKey& __exk,
977 const allocator_type& __a)
978 : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
979 {
980 auto __nb_elems = __detail::__distance_fw(__f, __l);
981 auto __bkt_count =
982 _M_rehash_policy._M_next_bkt(
983 std::max(_M_rehash_policy._M_bkt_for_elements(__nb_elems),
984 __bucket_hint));
985
986 if (__bkt_count > _M_bucket_count)
987 {
988 _M_buckets = _M_allocate_buckets(__bkt_count);
989 _M_bucket_count = __bkt_count;
990 }
991
992 for (; __f != __l; ++__f)
993 this->insert(*__f);
994 }
995
996 template<typename _Key, typename _Value,
997 typename _Alloc, typename _ExtractKey, typename _Equal,
998 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
999 typename _Traits>
1000 auto
1001 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1002 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1003 operator=(const _Hashtable& __ht)
1004 -> _Hashtable&
1005 {
1006 if (&__ht == this)
1007 return *this;
1008
1009 if (__node_alloc_traits::_S_propagate_on_copy_assign())
1010 {
1011 auto& __this_alloc = this->_M_node_allocator();
1012 auto& __that_alloc = __ht._M_node_allocator();
1013 if (!__node_alloc_traits::_S_always_equal()
1014 && __this_alloc != __that_alloc)
1015 {
1016 // Replacement allocator cannot free existing storage.
1017 this->_M_deallocate_nodes(_M_begin());
1018 _M_before_begin._M_nxt = nullptr;
1019 _M_deallocate_buckets();
1020 _M_buckets = nullptr;
1021 std::__alloc_on_copy(__this_alloc, __that_alloc);
1022 __hashtable_base::operator=(__ht);
1023 _M_bucket_count = __ht._M_bucket_count;
1024 _M_element_count = __ht._M_element_count;
1025 _M_rehash_policy = __ht._M_rehash_policy;
1026 __try
1027 {
1028 _M_assign(__ht,
1029 [this](const __node_type* __n)
1030 { return this->_M_allocate_node(__n->_M_v()); });
1031 }
1032 __catch(...)
1033 {
1034 // _M_assign took care of deallocating all memory. Now we
1035 // must make sure this instance remains in a usable state.
1036 _M_reset();
1037 __throw_exception_again;
1038 }
1039 return *this;
1040 }
1041 std::__alloc_on_copy(__this_alloc, __that_alloc);
1042 }
1043
1044 // Reuse allocated buckets and nodes.
1045 __bucket_type* __former_buckets = nullptr;
1046 std::size_t __former_bucket_count = _M_bucket_count;
1047 const __rehash_state& __former_state = _M_rehash_policy._M_state();
1048
1049 if (_M_bucket_count != __ht._M_bucket_count)
1050 {
1051 __former_buckets = _M_buckets;
1052 _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
1053 _M_bucket_count = __ht._M_bucket_count;
1054 }
1055 else
1056 __builtin_memset(_M_buckets, 0,
1057 _M_bucket_count * sizeof(__bucket_type));
1058
1059 __try
1060 {
1061 __hashtable_base::operator=(__ht);
1062 _M_element_count = __ht._M_element_count;
1063 _M_rehash_policy = __ht._M_rehash_policy;
1064 __reuse_or_alloc_node_type __roan(_M_begin(), *this);
1065 _M_before_begin._M_nxt = nullptr;
1066 _M_assign(__ht,
1067 [&__roan](const __node_type* __n)
1068 { return __roan(__n->_M_v()); });
1069 if (__former_buckets)
1070 _M_deallocate_buckets(__former_buckets, __former_bucket_count);
1071 }
1072 __catch(...)
1073 {
1074 if (__former_buckets)
1075 {
1076 // Restore previous buckets.
1077 _M_deallocate_buckets();
1078 _M_rehash_policy._M_reset(__former_state);
1079 _M_buckets = __former_buckets;
1080 _M_bucket_count = __former_bucket_count;
1081 }
1082 __builtin_memset(_M_buckets, 0,
1083 _M_bucket_count * sizeof(__bucket_type));
1084 __throw_exception_again;
1085 }
1086 return *this;
1087 }
1088
1089 template<typename _Key, typename _Value,
1090 typename _Alloc, typename _ExtractKey, typename _Equal,
1091 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1092 typename _Traits>
1093 template<typename _NodeGenerator>
1094 void
1095 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1096 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1097 _M_assign(const _Hashtable& __ht, const _NodeGenerator& __node_gen)
1098 {
1099 __bucket_type* __buckets = nullptr;
1100 if (!_M_buckets)
1101 _M_buckets = __buckets = _M_allocate_buckets(_M_bucket_count);
1102
1103 __try
1104 {
1105 if (!__ht._M_before_begin._M_nxt)
1106 return;
1107
1108 // First deal with the special first node pointed to by
1109 // _M_before_begin.
1110 __node_type* __ht_n = __ht._M_begin();
1111 __node_type* __this_n = __node_gen(__ht_n);
1112 this->_M_copy_code(__this_n, __ht_n);
1113 _M_before_begin._M_nxt = __this_n;
1114 _M_buckets[_M_bucket_index(__this_n)] = &_M_before_begin;
1115
1116 // Then deal with other nodes.
1117 __node_base* __prev_n = __this_n;
1118 for (__ht_n = __ht_n->_M_next(); __ht_n; __ht_n = __ht_n->_M_next())
1119 {
1120 __this_n = __node_gen(__ht_n);
1121 __prev_n->_M_nxt = __this_n;
1122 this->_M_copy_code(__this_n, __ht_n);
1123 size_type __bkt = _M_bucket_index(__this_n);
1124 if (!_M_buckets[__bkt])
1125 _M_buckets[__bkt] = __prev_n;
1126 __prev_n = __this_n;
1127 }
1128 }
1129 __catch(...)
1130 {
1131 clear();
1132 if (__buckets)
1133 _M_deallocate_buckets();
1134 __throw_exception_again;
1135 }
1136 }
1137
1138 template<typename _Key, typename _Value,
1139 typename _Alloc, typename _ExtractKey, typename _Equal,
1140 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1141 typename _Traits>
1142 void
1143 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1144 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1145 _M_reset() noexcept
1146 {
1147 _M_rehash_policy._M_reset();
1148 _M_bucket_count = 1;
1149 _M_single_bucket = nullptr;
1150 _M_buckets = &_M_single_bucket;
1151 _M_before_begin._M_nxt = nullptr;
1152 _M_element_count = 0;
1153 }
1154
1155 template<typename _Key, typename _Value,
1156 typename _Alloc, typename _ExtractKey, typename _Equal,
1157 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1158 typename _Traits>
1159 void
1160 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1161 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1162 _M_move_assign(_Hashtable&& __ht, std::true_type)
1163 {
1164 this->_M_deallocate_nodes(_M_begin());
1165 _M_deallocate_buckets();
1166 __hashtable_base::operator=(std::move(__ht));
1167 _M_rehash_policy = __ht._M_rehash_policy;
1168 if (!__ht._M_uses_single_bucket())
1169 _M_buckets = __ht._M_buckets;
1170 else
1171 {
1172 _M_buckets = &_M_single_bucket;
1173 _M_single_bucket = __ht._M_single_bucket;
1174 }
1175 _M_bucket_count = __ht._M_bucket_count;
1176 _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
1177 _M_element_count = __ht._M_element_count;
1178 std::__alloc_on_move(this->_M_node_allocator(), __ht._M_node_allocator());
1179
1180 // Fix buckets containing the _M_before_begin pointers that can't be
1181 // moved.
1182 if (_M_begin())
1183 _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1184 __ht._M_reset();
1185 }
1186
1187 template<typename _Key, typename _Value,
1188 typename _Alloc, typename _ExtractKey, typename _Equal,
1189 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1190 typename _Traits>
1191 void
1192 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1193 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1194 _M_move_assign(_Hashtable&& __ht, std::false_type)
1195 {
1196 if (__ht._M_node_allocator() == this->_M_node_allocator())
1197 _M_move_assign(std::move(__ht), std::true_type());
1198 else
1199 {
1200 // Can't move memory, move elements then.
1201 __bucket_type* __former_buckets = nullptr;
1202 size_type __former_bucket_count = _M_bucket_count;
1203 const __rehash_state& __former_state = _M_rehash_policy._M_state();
1204
1205 if (_M_bucket_count != __ht._M_bucket_count)
1206 {
1207 __former_buckets = _M_buckets;
1208 _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
1209 _M_bucket_count = __ht._M_bucket_count;
1210 }
1211 else
1212 __builtin_memset(_M_buckets, 0,
1213 _M_bucket_count * sizeof(__bucket_type));
1214
1215 __try
1216 {
1217 __hashtable_base::operator=(std::move(__ht));
1218 _M_element_count = __ht._M_element_count;
1219 _M_rehash_policy = __ht._M_rehash_policy;
1220 __reuse_or_alloc_node_type __roan(_M_begin(), *this);
1221 _M_before_begin._M_nxt = nullptr;
1222 _M_assign(__ht,
1223 [&__roan](__node_type* __n)
1224 { return __roan(std::move_if_noexcept(__n->_M_v())); });
1225
1226 if (__former_buckets)
1227 _M_deallocate_buckets(__former_buckets, __former_bucket_count);
1228 __ht.clear();
1229 }
1230 __catch(...)
1231 {
1232 if (__former_buckets)
1233 {
1234 _M_deallocate_buckets();
1235 _M_rehash_policy._M_reset(__former_state);
1236 _M_buckets = __former_buckets;
1237 _M_bucket_count = __former_bucket_count;
1238 }
1239 __builtin_memset(_M_buckets, 0,
1240 _M_bucket_count * sizeof(__bucket_type));
1241 __throw_exception_again;
1242 }
1243 }
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(const _Hashtable& __ht)
1253 : __hashtable_base(__ht),
1254 __map_base(__ht),
1255 __rehash_base(__ht),
1256 __hashtable_alloc(
1257 __node_alloc_traits::_S_select_on_copy(__ht._M_node_allocator())),
1258 _M_buckets(nullptr),
1259 _M_bucket_count(__ht._M_bucket_count),
1260 _M_element_count(__ht._M_element_count),
1261 _M_rehash_policy(__ht._M_rehash_policy)
1262 {
1263 _M_assign(__ht,
1264 [this](const __node_type* __n)
1265 { return this->_M_allocate_node(__n->_M_v()); });
1266 }
1267
1268 template<typename _Key, typename _Value,
1269 typename _Alloc, typename _ExtractKey, typename _Equal,
1270 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1271 typename _Traits>
1272 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1273 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1274 _Hashtable(_Hashtable&& __ht) noexcept
1275 : __hashtable_base(__ht),
1276 __map_base(__ht),
1277 __rehash_base(__ht),
1278 __hashtable_alloc(std::move(__ht._M_base_alloc())),
1279 _M_buckets(__ht._M_buckets),
1280 _M_bucket_count(__ht._M_bucket_count),
1281 _M_before_begin(__ht._M_before_begin._M_nxt),
1282 _M_element_count(__ht._M_element_count),
1283 _M_rehash_policy(__ht._M_rehash_policy)
1284 {
1285 // Update, if necessary, buckets if __ht is using its single bucket.
1286 if (__ht._M_uses_single_bucket())
1287 {
1288 _M_buckets = &_M_single_bucket;
1289 _M_single_bucket = __ht._M_single_bucket;
1290 }
1291
1292 // Update, if necessary, bucket pointing to before begin that hasn't
1293 // moved.
1294 if (_M_begin())
1295 _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1296
1297 __ht._M_reset();
1298 }
1299
1300 template<typename _Key, typename _Value,
1301 typename _Alloc, typename _ExtractKey, typename _Equal,
1302 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1303 typename _Traits>
1304 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1305 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1306 _Hashtable(const _Hashtable& __ht, const allocator_type& __a)
1307 : __hashtable_base(__ht),
1308 __map_base(__ht),
1309 __rehash_base(__ht),
1310 __hashtable_alloc(__node_alloc_type(__a)),
1311 _M_buckets(),
1312 _M_bucket_count(__ht._M_bucket_count),
1313 _M_element_count(__ht._M_element_count),
1314 _M_rehash_policy(__ht._M_rehash_policy)
1315 {
1316 _M_assign(__ht,
1317 [this](const __node_type* __n)
1318 { return this->_M_allocate_node(__n->_M_v()); });
1319 }
1320
1321 template<typename _Key, typename _Value,
1322 typename _Alloc, typename _ExtractKey, typename _Equal,
1323 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1324 typename _Traits>
1325 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1326 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1327 _Hashtable(_Hashtable&& __ht, const allocator_type& __a)
1328 : __hashtable_base(__ht),
1329 __map_base(__ht),
1330 __rehash_base(__ht),
1331 __hashtable_alloc(__node_alloc_type(__a)),
1332 _M_buckets(nullptr),
1333 _M_bucket_count(__ht._M_bucket_count),
1334 _M_element_count(__ht._M_element_count),
1335 _M_rehash_policy(__ht._M_rehash_policy)
1336 {
1337 if (__ht._M_node_allocator() == this->_M_node_allocator())
1338 {
1339 if (__ht._M_uses_single_bucket())
1340 {
1341 _M_buckets = &_M_single_bucket;
1342 _M_single_bucket = __ht._M_single_bucket;
1343 }
1344 else
1345 _M_buckets = __ht._M_buckets;
1346
1347 _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
1348 // Update, if necessary, bucket pointing to before begin that hasn't
1349 // moved.
1350 if (_M_begin())
1351 _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1352 __ht._M_reset();
1353 }
1354 else
1355 {
1356 _M_assign(__ht,
1357 [this](__node_type* __n)
1358 {
1359 return this->_M_allocate_node(
1360 std::move_if_noexcept(__n->_M_v()));
1361 });
1362 __ht.clear();
1363 }
1364 }
1365
1366 template<typename _Key, typename _Value,
1367 typename _Alloc, typename _ExtractKey, typename _Equal,
1368 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1369 typename _Traits>
1370 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1371 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1372 ~_Hashtable() noexcept
1373 {
1374 clear();
1375 _M_deallocate_buckets();
1376 }
1377
1378 template<typename _Key, typename _Value,
1379 typename _Alloc, typename _ExtractKey, typename _Equal,
1380 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1381 typename _Traits>
1382 void
1383 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1384 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1385 swap(_Hashtable& __x)
1386 noexcept(__and_<__is_nothrow_swappable<_H1>,
1387 __is_nothrow_swappable<_Equal>>::value)
1388 {
1389 // The only base class with member variables is hash_code_base.
1390 // We define _Hash_code_base::_M_swap because different
1391 // specializations have different members.
1392 this->_M_swap(__x);
1393
1394 std::__alloc_on_swap(this->_M_node_allocator(), __x._M_node_allocator());
1395 std::swap(_M_rehash_policy, __x._M_rehash_policy);
1396
1397 // Deal properly with potentially moved instances.
1398 if (this->_M_uses_single_bucket())
1399 {
1400 if (!__x._M_uses_single_bucket())
1401 {
1402 _M_buckets = __x._M_buckets;
1403 __x._M_buckets = &__x._M_single_bucket;
1404 }
1405 }
1406 else if (__x._M_uses_single_bucket())
1407 {
1408 __x._M_buckets = _M_buckets;
1409 _M_buckets = &_M_single_bucket;
1410 }
1411 else
1412 std::swap(_M_buckets, __x._M_buckets);
1413
1414 std::swap(_M_bucket_count, __x._M_bucket_count);
1415 std::swap(_M_before_begin._M_nxt, __x._M_before_begin._M_nxt);
1416 std::swap(_M_element_count, __x._M_element_count);
1417 std::swap(_M_single_bucket, __x._M_single_bucket);
1418
1419 // Fix buckets containing the _M_before_begin pointers that can't be
1420 // swapped.
1421 if (_M_begin())
1422 _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1423
1424 if (__x._M_begin())
1425 __x._M_buckets[__x._M_bucket_index(__x._M_begin())]
1426 = &__x._M_before_begin;
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)
1437 -> 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 ? 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 find(const key_type& __k) const
1453 -> const_iterator
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_find_node(__n, __k, __code);
1458 return __p ? const_iterator(__p) : end();
1459 }
1460
1461 template<typename _Key, typename _Value,
1462 typename _Alloc, typename _ExtractKey, typename _Equal,
1463 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1464 typename _Traits>
1465 auto
1466 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1467 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1468 count(const key_type& __k) const
1469 -> size_type
1470 {
1471 __hash_code __code = this->_M_hash_code(__k);
1472 std::size_t __n = _M_bucket_index(__k, __code);
1473 __node_type* __p = _M_bucket_begin(__n);
1474 if (!__p)
1475 return 0;
1476
1477 std::size_t __result = 0;
1478 for (;; __p = __p->_M_next())
1479 {
1480 if (this->_M_equals(__k, __code, __p))
1481 ++__result;
1482 else if (__result)
1483 // All equivalent values are next to each other, if we
1484 // found a non-equivalent value after an equivalent one it
1485 // means that we won't find any new equivalent value.
1486 break;
1487 if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
1488 break;
1489 }
1490 return __result;
1491 }
1492
1493 template<typename _Key, typename _Value,
1494 typename _Alloc, typename _ExtractKey, typename _Equal,
1495 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1496 typename _Traits>
1497 auto
1498 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1499 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1500 equal_range(const key_type& __k)
1501 -> pair<iterator, iterator>
1502 {
1503 __hash_code __code = this->_M_hash_code(__k);
1504 std::size_t __n = _M_bucket_index(__k, __code);
1505 __node_type* __p = _M_find_node(__n, __k, __code);
1506
1507 if (__p)
1508 {
1509 __node_type* __p1 = __p->_M_next();
1510 while (__p1 && _M_bucket_index(__p1) == __n
1511 && this->_M_equals(__k, __code, __p1))
1512 __p1 = __p1->_M_next();
1513
1514 return std::make_pair(iterator(__p), iterator(__p1));
1515 }
1516 else
1517 return std::make_pair(end(), end());
1518 }
1519
1520 template<typename _Key, typename _Value,
1521 typename _Alloc, typename _ExtractKey, typename _Equal,
1522 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1523 typename _Traits>
1524 auto
1525 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1526 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1527 equal_range(const key_type& __k) const
1528 -> pair<const_iterator, const_iterator>
1529 {
1530 __hash_code __code = this->_M_hash_code(__k);
1531 std::size_t __n = _M_bucket_index(__k, __code);
1532 __node_type* __p = _M_find_node(__n, __k, __code);
1533
1534 if (__p)
1535 {
1536 __node_type* __p1 = __p->_M_next();
1537 while (__p1 && _M_bucket_index(__p1) == __n
1538 && this->_M_equals(__k, __code, __p1))
1539 __p1 = __p1->_M_next();
1540
1541 return std::make_pair(const_iterator(__p), const_iterator(__p1));
1542 }
1543 else
1544 return std::make_pair(end(), end());
1545 }
1546
1547 // Find the node whose key compares equal to k in the bucket n.
1548 // Return nullptr if no node is found.
1549 template<typename _Key, typename _Value,
1550 typename _Alloc, typename _ExtractKey, typename _Equal,
1551 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1552 typename _Traits>
1553 auto
1554 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1555 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1556 _M_find_before_node(size_type __n, const key_type& __k,
1557 __hash_code __code) const
1558 -> __node_base*
1559 {
1560 __node_base* __prev_p = _M_buckets[__n];
1561 if (!__prev_p)
1562 return nullptr;
1563
1564 for (__node_type* __p = static_cast<__node_type*>(__prev_p->_M_nxt);;
1565 __p = __p->_M_next())
1566 {
1567 if (this->_M_equals(__k, __code, __p))
1568 return __prev_p;
1569
1570 if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
1571 break;
1572 __prev_p = __p;
1573 }
1574 return nullptr;
1575 }
1576
1577 template<typename _Key, typename _Value,
1578 typename _Alloc, typename _ExtractKey, typename _Equal,
1579 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1580 typename _Traits>
1581 void
1582 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1583 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1584 _M_insert_bucket_begin(size_type __bkt, __node_type* __node)
1585 {
1586 if (_M_buckets[__bkt])
1587 {
1588 // Bucket is not empty, we just need to insert the new node
1589 // after the bucket before begin.
1590 __node->_M_nxt = _M_buckets[__bkt]->_M_nxt;
1591 _M_buckets[__bkt]->_M_nxt = __node;
1592 }
1593 else
1594 {
1595 // The bucket is empty, the new node is inserted at the
1596 // beginning of the singly-linked list and the bucket will
1597 // contain _M_before_begin pointer.
1598 __node->_M_nxt = _M_before_begin._M_nxt;
1599 _M_before_begin._M_nxt = __node;
1600 if (__node->_M_nxt)
1601 // We must update former begin bucket that is pointing to
1602 // _M_before_begin.
1603 _M_buckets[_M_bucket_index(__node->_M_next())] = __node;
1604 _M_buckets[__bkt] = &_M_before_begin;
1605 }
1606 }
1607
1608 template<typename _Key, typename _Value,
1609 typename _Alloc, typename _ExtractKey, typename _Equal,
1610 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1611 typename _Traits>
1612 void
1613 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1614 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1615 _M_remove_bucket_begin(size_type __bkt, __node_type* __next,
1616 size_type __next_bkt)
1617 {
1618 if (!__next || __next_bkt != __bkt)
1619 {
1620 // Bucket is now empty
1621 // First update next bucket if any
1622 if (__next)
1623 _M_buckets[__next_bkt] = _M_buckets[__bkt];
1624
1625 // Second update before begin node if necessary
1626 if (&_M_before_begin == _M_buckets[__bkt])
1627 _M_before_begin._M_nxt = __next;
1628 _M_buckets[__bkt] = nullptr;
1629 }
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 auto
1637 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1638 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1639 _M_get_previous_node(size_type __bkt, __node_base* __n)
1640 -> __node_base*
1641 {
1642 __node_base* __prev_n = _M_buckets[__bkt];
1643 while (__prev_n->_M_nxt != __n)
1644 __prev_n = __prev_n->_M_nxt;
1645 return __prev_n;
1646 }
1647
1648 template<typename _Key, typename _Value,
1649 typename _Alloc, typename _ExtractKey, typename _Equal,
1650 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1651 typename _Traits>
1652 template<typename... _Args>
1653 auto
1654 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1655 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1656 _M_emplace(std::true_type, _Args&&... __args)
1657 -> pair<iterator, bool>
1658 {
1659 // First build the node to get access to the hash code
1660 __node_type* __node = this->_M_allocate_node(std::forward<_Args>(__args)...);
1661 const key_type& __k = this->_M_extract()(__node->_M_v());
1662 __hash_code __code;
1663 __try
1664 {
1665 __code = this->_M_hash_code(__k);
1666 }
1667 __catch(...)
1668 {
1669 this->_M_deallocate_node(__node);
1670 __throw_exception_again;
1671 }
1672
1673 size_type __bkt = _M_bucket_index(__k, __code);
1674 if (__node_type* __p = _M_find_node(__bkt, __k, __code))
1675 {
1676 // There is already an equivalent node, no insertion
1677 this->_M_deallocate_node(__node);
1678 return std::make_pair(iterator(__p), false);
1679 }
1680
1681 // Insert the node
1682 return std::make_pair(_M_insert_unique_node(__bkt, __code, __node),
1683 true);
1684 }
1685
1686 template<typename _Key, typename _Value,
1687 typename _Alloc, typename _ExtractKey, typename _Equal,
1688 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1689 typename _Traits>
1690 template<typename... _Args>
1691 auto
1692 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1693 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1694 _M_emplace(const_iterator __hint, std::false_type, _Args&&... __args)
1695 -> iterator
1696 {
1697 // First build the node to get its hash code.
1698 __node_type* __node =
1699 this->_M_allocate_node(std::forward<_Args>(__args)...);
1700
1701 __hash_code __code;
1702 __try
1703 {
1704 __code = this->_M_hash_code(this->_M_extract()(__node->_M_v()));
1705 }
1706 __catch(...)
1707 {
1708 this->_M_deallocate_node(__node);
1709 __throw_exception_again;
1710 }
1711
1712 return _M_insert_multi_node(__hint._M_cur, __code, __node);
1713 }
1714
1715 template<typename _Key, typename _Value,
1716 typename _Alloc, typename _ExtractKey, typename _Equal,
1717 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1718 typename _Traits>
1719 auto
1720 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1721 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1722 _M_insert_unique_node(size_type __bkt, __hash_code __code,
1723 __node_type* __node, size_type __n_elt)
1724 -> iterator
1725 {
1726 const __rehash_state& __saved_state = _M_rehash_policy._M_state();
1727 std::pair<bool, std::size_t> __do_rehash
1728 = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count,
1729 __n_elt);
1730
1731 __try
1732 {
1733 if (__do_rehash.first)
1734 {
1735 _M_rehash(__do_rehash.second, __saved_state);
1736 __bkt = _M_bucket_index(this->_M_extract()(__node->_M_v()), __code);
1737 }
1738
1739 this->_M_store_code(__node, __code);
1740
1741 // Always insert at the beginning of the bucket.
1742 _M_insert_bucket_begin(__bkt, __node);
1743 ++_M_element_count;
1744 return iterator(__node);
1745 }
1746 __catch(...)
1747 {
1748 this->_M_deallocate_node(__node);
1749 __throw_exception_again;
1750 }
1751 }
1752
1753 // Insert node, in bucket bkt if no rehash (assumes no element with its key
1754 // already present). Take ownership of the node, deallocate it on exception.
1755 template<typename _Key, typename _Value,
1756 typename _Alloc, typename _ExtractKey, typename _Equal,
1757 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1758 typename _Traits>
1759 auto
1760 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1761 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1762 _M_insert_multi_node(__node_type* __hint, __hash_code __code,
1763 __node_type* __node)
1764 -> iterator
1765 {
1766 const __rehash_state& __saved_state = _M_rehash_policy._M_state();
1767 std::pair<bool, std::size_t> __do_rehash
1768 = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count, 1);
1769
1770 __try
1771 {
1772 if (__do_rehash.first)
1773 _M_rehash(__do_rehash.second, __saved_state);
1774
1775 this->_M_store_code(__node, __code);
1776 const key_type& __k = this->_M_extract()(__node->_M_v());
1777 size_type __bkt = _M_bucket_index(__k, __code);
1778
1779 // Find the node before an equivalent one or use hint if it exists and
1780 // if it is equivalent.
1781 __node_base* __prev
1782 = __builtin_expect(__hint != nullptr, false)
1783 && this->_M_equals(__k, __code, __hint)
1784 ? __hint
1785 : _M_find_before_node(__bkt, __k, __code);
1786 if (__prev)
1787 {
1788 // Insert after the node before the equivalent one.
1789 __node->_M_nxt = __prev->_M_nxt;
1790 __prev->_M_nxt = __node;
1791 if (__builtin_expect(__prev == __hint, false))
1792 // hint might be the last bucket node, in this case we need to
1793 // update next bucket.
1794 if (__node->_M_nxt
1795 && !this->_M_equals(__k, __code, __node->_M_next()))
1796 {
1797 size_type __next_bkt = _M_bucket_index(__node->_M_next());
1798 if (__next_bkt != __bkt)
1799 _M_buckets[__next_bkt] = __node;
1800 }
1801 }
1802 else
1803 // The inserted node has no equivalent in the
1804 // hashtable. We must insert the new node at the
1805 // beginning of the bucket to preserve equivalent
1806 // elements' relative positions.
1807 _M_insert_bucket_begin(__bkt, __node);
1808 ++_M_element_count;
1809 return iterator(__node);
1810 }
1811 __catch(...)
1812 {
1813 this->_M_deallocate_node(__node);
1814 __throw_exception_again;
1815 }
1816 }
1817
1818 // Insert v if no element with its key is already present.
1819 template<typename _Key, typename _Value,
1820 typename _Alloc, typename _ExtractKey, typename _Equal,
1821 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1822 typename _Traits>
1823 template<typename _Arg, typename _NodeGenerator>
1824 auto
1825 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1826 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1827 _M_insert(_Arg&& __v, const _NodeGenerator& __node_gen, true_type,
1828 size_type __n_elt)
1829 -> pair<iterator, bool>
1830 {
1831 const key_type& __k = this->_M_extract()(__v);
1832 __hash_code __code = this->_M_hash_code(__k);
1833 size_type __bkt = _M_bucket_index(__k, __code);
1834
1835 __node_type* __n = _M_find_node(__bkt, __k, __code);
1836 if (__n)
1837 return std::make_pair(iterator(__n), false);
1838
1839 __n = __node_gen(std::forward<_Arg>(__v));
1840 return { _M_insert_unique_node(__bkt, __code, __n, __n_elt), true };
1841 }
1842
1843 // Insert v unconditionally.
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 template<typename _Arg, typename _NodeGenerator>
1849 auto
1850 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1851 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1852 _M_insert(const_iterator __hint, _Arg&& __v,
1853 const _NodeGenerator& __node_gen, false_type)
1854 -> iterator
1855 {
1856 // First compute the hash code so that we don't do anything if it
1857 // throws.
1858 __hash_code __code = this->_M_hash_code(this->_M_extract()(__v));
1859
1860 // Second allocate new node so that we don't rehash if it throws.
1861 __node_type* __node = __node_gen(std::forward<_Arg>(__v));
1862
1863 return _M_insert_multi_node(__hint._M_cur, __code, __node);
1864 }
1865
1866 template<typename _Key, typename _Value,
1867 typename _Alloc, typename _ExtractKey, typename _Equal,
1868 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1869 typename _Traits>
1870 auto
1871 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1872 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1873 erase(const_iterator __it)
1874 -> iterator
1875 {
1876 __node_type* __n = __it._M_cur;
1877 std::size_t __bkt = _M_bucket_index(__n);
1878
1879 // Look for previous node to unlink it from the erased one, this
1880 // is why we need buckets to contain the before begin to make
1881 // this search fast.
1882 __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
1883 return _M_erase(__bkt, __prev_n, __n);
1884 }
1885
1886 template<typename _Key, typename _Value,
1887 typename _Alloc, typename _ExtractKey, typename _Equal,
1888 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1889 typename _Traits>
1890 auto
1891 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1892 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1893 _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n)
1894 -> iterator
1895 {
1896 if (__prev_n == _M_buckets[__bkt])
1897 _M_remove_bucket_begin(__bkt, __n->_M_next(),
1898 __n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
1899 else if (__n->_M_nxt)
1900 {
1901 size_type __next_bkt = _M_bucket_index(__n->_M_next());
1902 if (__next_bkt != __bkt)
1903 _M_buckets[__next_bkt] = __prev_n;
1904 }
1905
1906 __prev_n->_M_nxt = __n->_M_nxt;
1907 iterator __result(__n->_M_next());
1908 this->_M_deallocate_node(__n);
1909 --_M_element_count;
1910
1911 return __result;
1912 }
1913
1914 template<typename _Key, typename _Value,
1915 typename _Alloc, typename _ExtractKey, typename _Equal,
1916 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1917 typename _Traits>
1918 auto
1919 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1920 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1921 _M_erase(std::true_type, const key_type& __k)
1922 -> size_type
1923 {
1924 __hash_code __code = this->_M_hash_code(__k);
1925 std::size_t __bkt = _M_bucket_index(__k, __code);
1926
1927 // Look for the node before the first matching node.
1928 __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
1929 if (!__prev_n)
1930 return 0;
1931
1932 // We found a matching node, erase it.
1933 __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
1934 _M_erase(__bkt, __prev_n, __n);
1935 return 1;
1936 }
1937
1938 template<typename _Key, typename _Value,
1939 typename _Alloc, typename _ExtractKey, typename _Equal,
1940 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1941 typename _Traits>
1942 auto
1943 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1944 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1945 _M_erase(std::false_type, const key_type& __k)
1946 -> size_type
1947 {
1948 __hash_code __code = this->_M_hash_code(__k);
1949 std::size_t __bkt = _M_bucket_index(__k, __code);
1950
1951 // Look for the node before the first matching node.
1952 __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
1953 if (!__prev_n)
1954 return 0;
1955
1956 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1957 // 526. Is it undefined if a function in the standard changes
1958 // in parameters?
1959 // We use one loop to find all matching nodes and another to deallocate
1960 // them so that the key stays valid during the first loop. It might be
1961 // invalidated indirectly when destroying nodes.
1962 __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
1963 __node_type* __n_last = __n;
1964 std::size_t __n_last_bkt = __bkt;
1965 do
1966 {
1967 __n_last = __n_last->_M_next();
1968 if (!__n_last)
1969 break;
1970 __n_last_bkt = _M_bucket_index(__n_last);
1971 }
1972 while (__n_last_bkt == __bkt && this->_M_equals(__k, __code, __n_last));
1973
1974 // Deallocate nodes.
1975 size_type __result = 0;
1976 do
1977 {
1978 __node_type* __p = __n->_M_next();
1979 this->_M_deallocate_node(__n);
1980 __n = __p;
1981 ++__result;
1982 --_M_element_count;
1983 }
1984 while (__n != __n_last);
1985
1986 if (__prev_n == _M_buckets[__bkt])
1987 _M_remove_bucket_begin(__bkt, __n_last, __n_last_bkt);
1988 else if (__n_last && __n_last_bkt != __bkt)
1989 _M_buckets[__n_last_bkt] = __prev_n;
1990 __prev_n->_M_nxt = __n_last;
1991 return __result;
1992 }
1993
1994 template<typename _Key, typename _Value,
1995 typename _Alloc, typename _ExtractKey, typename _Equal,
1996 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1997 typename _Traits>
1998 auto
1999 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2000 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2001 erase(const_iterator __first, const_iterator __last)
2002 -> iterator
2003 {
2004 __node_type* __n = __first._M_cur;
2005 __node_type* __last_n = __last._M_cur;
2006 if (__n == __last_n)
2007 return iterator(__n);
2008
2009 std::size_t __bkt = _M_bucket_index(__n);
2010
2011 __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
2012 bool __is_bucket_begin = __n == _M_bucket_begin(__bkt);
2013 std::size_t __n_bkt = __bkt;
2014 for (;;)
2015 {
2016 do
2017 {
2018 __node_type* __tmp = __n;
2019 __n = __n->_M_next();
2020 this->_M_deallocate_node(__tmp);
2021 --_M_element_count;
2022 if (!__n)
2023 break;
2024 __n_bkt = _M_bucket_index(__n);
2025 }
2026 while (__n != __last_n && __n_bkt == __bkt);
2027 if (__is_bucket_begin)
2028 _M_remove_bucket_begin(__bkt, __n, __n_bkt);
2029 if (__n == __last_n)
2030 break;
2031 __is_bucket_begin = true;
2032 __bkt = __n_bkt;
2033 }
2034
2035 if (__n && (__n_bkt != __bkt || __is_bucket_begin))
2036 _M_buckets[__n_bkt] = __prev_n;
2037 __prev_n->_M_nxt = __n;
2038 return iterator(__n);
2039 }
2040
2041 template<typename _Key, typename _Value,
2042 typename _Alloc, typename _ExtractKey, typename _Equal,
2043 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2044 typename _Traits>
2045 void
2046 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2047 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2048 clear() noexcept
2049 {
2050 this->_M_deallocate_nodes(_M_begin());
2051 __builtin_memset(_M_buckets, 0, _M_bucket_count * sizeof(__bucket_type));
2052 _M_element_count = 0;
2053 _M_before_begin._M_nxt = nullptr;
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 rehash(size_type __n)
2064 {
2065 const __rehash_state& __saved_state = _M_rehash_policy._M_state();
2066 std::size_t __buckets
2067 = std::max(_M_rehash_policy._M_bkt_for_elements(_M_element_count + 1),
2068 __n);
2069 __buckets = _M_rehash_policy._M_next_bkt(__buckets);
2070
2071 if (__buckets != _M_bucket_count)
2072 _M_rehash(__buckets, __saved_state);
2073 else
2074 // No rehash, restore previous state to keep a consistent state.
2075 _M_rehash_policy._M_reset(__saved_state);
2076 }
2077
2078 template<typename _Key, typename _Value,
2079 typename _Alloc, typename _ExtractKey, typename _Equal,
2080 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2081 typename _Traits>
2082 void
2083 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2084 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2085 _M_rehash(size_type __n, const __rehash_state& __state)
2086 {
2087 __try
2088 {
2089 _M_rehash_aux(__n, __unique_keys());
2090 }
2091 __catch(...)
2092 {
2093 // A failure here means that buckets allocation failed. We only
2094 // have to restore hash policy previous state.
2095 _M_rehash_policy._M_reset(__state);
2096 __throw_exception_again;
2097 }
2098 }
2099
2100 // Rehash when there is no equivalent elements.
2101 template<typename _Key, typename _Value,
2102 typename _Alloc, typename _ExtractKey, typename _Equal,
2103 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2104 typename _Traits>
2105 void
2106 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2107 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2108 _M_rehash_aux(size_type __n, std::true_type)
2109 {
2110 __bucket_type* __new_buckets = _M_allocate_buckets(__n);
2111 __node_type* __p = _M_begin();
2112 _M_before_begin._M_nxt = nullptr;
2113 std::size_t __bbegin_bkt = 0;
2114 while (__p)
2115 {
2116 __node_type* __next = __p->_M_next();
2117 std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
2118 if (!__new_buckets[__bkt])
2119 {
2120 __p->_M_nxt = _M_before_begin._M_nxt;
2121 _M_before_begin._M_nxt = __p;
2122 __new_buckets[__bkt] = &_M_before_begin;
2123 if (__p->_M_nxt)
2124 __new_buckets[__bbegin_bkt] = __p;
2125 __bbegin_bkt = __bkt;
2126 }
2127 else
2128 {
2129 __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2130 __new_buckets[__bkt]->_M_nxt = __p;
2131 }
2132 __p = __next;
2133 }
2134
2135 _M_deallocate_buckets();
2136 _M_bucket_count = __n;
2137 _M_buckets = __new_buckets;
2138 }
2139
2140 // Rehash when there can be equivalent elements, preserve their relative
2141 // order.
2142 template<typename _Key, typename _Value,
2143 typename _Alloc, typename _ExtractKey, typename _Equal,
2144 typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2145 typename _Traits>
2146 void
2147 _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2148 _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2149 _M_rehash_aux(size_type __n, std::false_type)
2150 {
2151 __bucket_type* __new_buckets = _M_allocate_buckets(__n);
2152
2153 __node_type* __p = _M_begin();
2154 _M_before_begin._M_nxt = nullptr;
2155 std::size_t __bbegin_bkt = 0;
2156 std::size_t __prev_bkt = 0;
2157 __node_type* __prev_p = nullptr;
2158 bool __check_bucket = false;
2159
2160 while (__p)
2161 {
2162 __node_type* __next = __p->_M_next();
2163 std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
2164
2165 if (__prev_p && __prev_bkt == __bkt)
2166 {
2167 // Previous insert was already in this bucket, we insert after
2168 // the previously inserted one to preserve equivalent elements
2169 // relative order.
2170 __p->_M_nxt = __prev_p->_M_nxt;
2171 __prev_p->_M_nxt = __p;
2172
2173 // Inserting after a node in a bucket require to check that we
2174 // haven't change the bucket last node, in this case next
2175 // bucket containing its before begin node must be updated. We
2176 // schedule a check as soon as we move out of the sequence of
2177 // equivalent nodes to limit the number of checks.
2178 __check_bucket = true;
2179 }
2180 else
2181 {
2182 if (__check_bucket)
2183 {
2184 // Check if we shall update the next bucket because of
2185 // insertions into __prev_bkt bucket.
2186 if (__prev_p->_M_nxt)
2187 {
2188 std::size_t __next_bkt
2189 = __hash_code_base::_M_bucket_index(__prev_p->_M_next(),
2190 __n);
2191 if (__next_bkt != __prev_bkt)
2192 __new_buckets[__next_bkt] = __prev_p;
2193 }
2194 __check_bucket = false;
2195 }
2196
2197 if (!__new_buckets[__bkt])
2198 {
2199 __p->_M_nxt = _M_before_begin._M_nxt;
2200 _M_before_begin._M_nxt = __p;
2201 __new_buckets[__bkt] = &_M_before_begin;
2202 if (__p->_M_nxt)
2203 __new_buckets[__bbegin_bkt] = __p;
2204 __bbegin_bkt = __bkt;
2205 }
2206 else
2207 {
2208 __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2209 __new_buckets[__bkt]->_M_nxt = __p;
2210 }
2211 }
2212 __prev_p = __p;
2213 __prev_bkt = __bkt;
2214 __p = __next;
2215 }
2216
2217 if (__check_bucket && __prev_p->_M_nxt)
2218 {
2219 std::size_t __next_bkt
2220 = __hash_code_base::_M_bucket_index(__prev_p->_M_next(), __n);
2221 if (__next_bkt != __prev_bkt)
2222 __new_buckets[__next_bkt] = __prev_p;
2223 }
2224
2225 _M_deallocate_buckets();
2226 _M_bucket_count = __n;
2227 _M_buckets = __new_buckets;
2228 }
2229
2230 #if __cplusplus > 201402L
2231 template<typename, typename, typename> class _Hash_merge_helper { };
2232 #endif // C++17
2233
2234 _GLIBCXX_END_NAMESPACE_VERSION
2235 } // namespace std
2236
2237 #endif // _HASHTABLE_H
2238