libstdc++
bits/hashtable.h
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1 // hashtable.h header -*- C++ -*-
2 
3 // Copyright (C) 2007-2021 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
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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
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15 
16 // Under Section 7 of GPL version 3, you are granted additional
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18 // 3.1, as published by the Free Software Foundation.
19 
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22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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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>
37 #if __cplusplus > 201402L
38 # include <bits/node_handle.h>
39 #endif
40 
41 namespace std _GLIBCXX_VISIBILITY(default)
42 {
43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
44 /// @cond undocumented
45 
46  template<typename _Tp, typename _Hash>
47  using __cache_default
48  = __not_<__and_<// Do not cache for fast hasher.
49  __is_fast_hash<_Hash>,
50  // Mandatory to have erase not throwing.
51  __is_nothrow_invocable<const _Hash&, const _Tp&>>>;
52 
53  // Helper to conditionally delete the default constructor.
54  // The _Hash_node_base type is used to distinguish this specialization
55  // from any other potentially-overlapping subobjects of the hashtable.
56  template<typename _Equal, typename _Hash, typename _Allocator>
57  using _Hashtable_enable_default_ctor
58  = _Enable_default_constructor<__and_<is_default_constructible<_Equal>,
59  is_default_constructible<_Hash>,
60  is_default_constructible<_Allocator>>{},
61  __detail::_Hash_node_base>;
62 
63  /**
64  * Primary class template _Hashtable.
65  *
66  * @ingroup hashtable-detail
67  *
68  * @tparam _Value CopyConstructible type.
69  *
70  * @tparam _Key CopyConstructible type.
71  *
72  * @tparam _Alloc An allocator type
73  * ([lib.allocator.requirements]) whose _Alloc::value_type is
74  * _Value. As a conforming extension, we allow for
75  * _Alloc::value_type != _Value.
76  *
77  * @tparam _ExtractKey Function object that takes an object of type
78  * _Value and returns a value of type _Key.
79  *
80  * @tparam _Equal Function object that takes two objects of type k
81  * and returns a bool-like value that is true if the two objects
82  * are considered equal.
83  *
84  * @tparam _Hash The hash function. A unary function object with
85  * argument type _Key and result type size_t. Return values should
86  * be distributed over the entire range [0, numeric_limits<size_t>:::max()].
87  *
88  * @tparam _RangeHash The range-hashing function (in the terminology of
89  * Tavori and Dreizin). A binary function object whose argument
90  * types and result type are all size_t. Given arguments r and N,
91  * the return value is in the range [0, N).
92  *
93  * @tparam _Unused Not used.
94  *
95  * @tparam _RehashPolicy Policy class with three members, all of
96  * which govern the bucket count. _M_next_bkt(n) returns a bucket
97  * count no smaller than n. _M_bkt_for_elements(n) returns a
98  * bucket count appropriate for an element count of n.
99  * _M_need_rehash(n_bkt, n_elt, n_ins) determines whether, if the
100  * current bucket count is n_bkt and the current element count is
101  * n_elt, we need to increase the bucket count for n_ins insertions.
102  * If so, returns make_pair(true, n), where n is the new bucket count. If
103  * not, returns make_pair(false, <anything>)
104  *
105  * @tparam _Traits Compile-time class with three boolean
106  * std::integral_constant members: __cache_hash_code, __constant_iterators,
107  * __unique_keys.
108  *
109  * Each _Hashtable data structure has:
110  *
111  * - _Bucket[] _M_buckets
112  * - _Hash_node_base _M_before_begin
113  * - size_type _M_bucket_count
114  * - size_type _M_element_count
115  *
116  * with _Bucket being _Hash_node_base* and _Hash_node containing:
117  *
118  * - _Hash_node* _M_next
119  * - Tp _M_value
120  * - size_t _M_hash_code if cache_hash_code is true
121  *
122  * In terms of Standard containers the hashtable is like the aggregation of:
123  *
124  * - std::forward_list<_Node> containing the elements
125  * - std::vector<std::forward_list<_Node>::iterator> representing the buckets
126  *
127  * The non-empty buckets contain the node before the first node in the
128  * bucket. This design makes it possible to implement something like a
129  * std::forward_list::insert_after on container insertion and
130  * std::forward_list::erase_after on container erase
131  * calls. _M_before_begin is equivalent to
132  * std::forward_list::before_begin. Empty buckets contain
133  * nullptr. Note that one of the non-empty buckets contains
134  * &_M_before_begin which is not a dereferenceable node so the
135  * node pointer in a bucket shall never be dereferenced, only its
136  * next node can be.
137  *
138  * Walking through a bucket's nodes requires a check on the hash code to
139  * see if each node is still in the bucket. Such a design assumes a
140  * quite efficient hash functor and is one of the reasons it is
141  * highly advisable to set __cache_hash_code to true.
142  *
143  * The container iterators are simply built from nodes. This way
144  * incrementing the iterator is perfectly efficient independent of
145  * how many empty buckets there are in the container.
146  *
147  * On insert we compute the element's hash code and use it to find the
148  * bucket index. If the element must be inserted in an empty bucket
149  * we add it at the beginning of the singly linked list and make the
150  * bucket point to _M_before_begin. The bucket that used to point to
151  * _M_before_begin, if any, is updated to point to its new before
152  * begin node.
153  *
154  * On erase, the simple iterator design requires using the hash
155  * functor to get the index of the bucket to update. For this
156  * reason, when __cache_hash_code is set to false the hash functor must
157  * not throw and this is enforced by a static assertion.
158  *
159  * Functionality is implemented by decomposition into base classes,
160  * where the derived _Hashtable class is used in _Map_base,
161  * _Insert, _Rehash_base, and _Equality base classes to access the
162  * "this" pointer. _Hashtable_base is used in the base classes as a
163  * non-recursive, fully-completed-type so that detailed nested type
164  * information, such as iterator type and node type, can be
165  * used. This is similar to the "Curiously Recurring Template
166  * Pattern" (CRTP) technique, but uses a reconstructed, not
167  * explicitly passed, template pattern.
168  *
169  * Base class templates are:
170  * - __detail::_Hashtable_base
171  * - __detail::_Map_base
172  * - __detail::_Insert
173  * - __detail::_Rehash_base
174  * - __detail::_Equality
175  */
176  template<typename _Key, typename _Value, typename _Alloc,
177  typename _ExtractKey, typename _Equal,
178  typename _Hash, typename _RangeHash, typename _Unused,
179  typename _RehashPolicy, typename _Traits>
180  class _Hashtable
181  : public __detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal,
182  _Hash, _RangeHash, _Unused, _Traits>,
183  public __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
184  _Hash, _RangeHash, _Unused,
185  _RehashPolicy, _Traits>,
186  public __detail::_Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
187  _Hash, _RangeHash, _Unused,
188  _RehashPolicy, _Traits>,
189  public __detail::_Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
190  _Hash, _RangeHash, _Unused,
191  _RehashPolicy, _Traits>,
192  public __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
193  _Hash, _RangeHash, _Unused,
194  _RehashPolicy, _Traits>,
195  private __detail::_Hashtable_alloc<
196  __alloc_rebind<_Alloc,
197  __detail::_Hash_node<_Value,
198  _Traits::__hash_cached::value>>>,
199  private _Hashtable_enable_default_ctor<_Equal, _Hash, _Alloc>
200  {
201  static_assert(is_same<typename remove_cv<_Value>::type, _Value>::value,
202  "unordered container must have a non-const, non-volatile value_type");
203 #if __cplusplus > 201703L || defined __STRICT_ANSI__
204  static_assert(is_same<typename _Alloc::value_type, _Value>{},
205  "unordered container must have the same value_type as its allocator");
206 #endif
207 
208  using __traits_type = _Traits;
209  using __hash_cached = typename __traits_type::__hash_cached;
210  using __constant_iterators = typename __traits_type::__constant_iterators;
211  using __node_type = __detail::_Hash_node<_Value, __hash_cached::value>;
212  using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>;
213 
214  using __hashtable_alloc = __detail::_Hashtable_alloc<__node_alloc_type>;
215 
216  using __node_value_type =
217  __detail::_Hash_node_value<_Value, __hash_cached::value>;
218  using __node_ptr = typename __hashtable_alloc::__node_ptr;
219  using __value_alloc_traits =
220  typename __hashtable_alloc::__value_alloc_traits;
221  using __node_alloc_traits =
222  typename __hashtable_alloc::__node_alloc_traits;
223  using __node_base = typename __hashtable_alloc::__node_base;
224  using __node_base_ptr = typename __hashtable_alloc::__node_base_ptr;
225  using __buckets_ptr = typename __hashtable_alloc::__buckets_ptr;
226 
227  using __insert_base = __detail::_Insert<_Key, _Value, _Alloc, _ExtractKey,
228  _Equal, _Hash,
229  _RangeHash, _Unused,
230  _RehashPolicy, _Traits>;
231  using __enable_default_ctor
232  = _Hashtable_enable_default_ctor<_Equal, _Hash, _Alloc>;
233 
234  public:
235  typedef _Key key_type;
236  typedef _Value value_type;
237  typedef _Alloc allocator_type;
238  typedef _Equal key_equal;
239 
240  // mapped_type, if present, comes from _Map_base.
241  // hasher, if present, comes from _Hash_code_base/_Hashtable_base.
242  typedef typename __value_alloc_traits::pointer pointer;
243  typedef typename __value_alloc_traits::const_pointer const_pointer;
244  typedef value_type& reference;
245  typedef const value_type& const_reference;
246 
247  using iterator = typename __insert_base::iterator;
248 
249  using const_iterator = typename __insert_base::const_iterator;
250 
251  using local_iterator = __detail::_Local_iterator<key_type, _Value,
252  _ExtractKey, _Hash, _RangeHash, _Unused,
253  __constant_iterators::value,
254  __hash_cached::value>;
255 
256  using const_local_iterator = __detail::_Local_const_iterator<
257  key_type, _Value,
258  _ExtractKey, _Hash, _RangeHash, _Unused,
259  __constant_iterators::value, __hash_cached::value>;
260 
261  private:
262  using __rehash_type = _RehashPolicy;
263  using __rehash_state = typename __rehash_type::_State;
264 
265  using __unique_keys = typename __traits_type::__unique_keys;
266 
267  using __hashtable_base = __detail::
268  _Hashtable_base<_Key, _Value, _ExtractKey,
269  _Equal, _Hash, _RangeHash, _Unused, _Traits>;
270 
271  using __hash_code_base = typename __hashtable_base::__hash_code_base;
272  using __hash_code = typename __hashtable_base::__hash_code;
273  using __ireturn_type = typename __insert_base::__ireturn_type;
274 
275  using __map_base = __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey,
276  _Equal, _Hash, _RangeHash, _Unused,
277  _RehashPolicy, _Traits>;
278 
279  using __rehash_base = __detail::_Rehash_base<_Key, _Value, _Alloc,
280  _ExtractKey, _Equal,
281  _Hash, _RangeHash, _Unused,
282  _RehashPolicy, _Traits>;
283 
284  using __eq_base = __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey,
285  _Equal, _Hash, _RangeHash, _Unused,
286  _RehashPolicy, _Traits>;
287 
288  using __reuse_or_alloc_node_gen_t =
289  __detail::_ReuseOrAllocNode<__node_alloc_type>;
290  using __alloc_node_gen_t =
291  __detail::_AllocNode<__node_alloc_type>;
292 
293  // Simple RAII type for managing a node containing an element
294  struct _Scoped_node
295  {
296  // Take ownership of a node with a constructed element.
297  _Scoped_node(__node_ptr __n, __hashtable_alloc* __h)
298  : _M_h(__h), _M_node(__n) { }
299 
300  // Allocate a node and construct an element within it.
301  template<typename... _Args>
302  _Scoped_node(__hashtable_alloc* __h, _Args&&... __args)
303  : _M_h(__h),
304  _M_node(__h->_M_allocate_node(std::forward<_Args>(__args)...))
305  { }
306 
307  // Destroy element and deallocate node.
308  ~_Scoped_node() { if (_M_node) _M_h->_M_deallocate_node(_M_node); };
309 
310  _Scoped_node(const _Scoped_node&) = delete;
311  _Scoped_node& operator=(const _Scoped_node&) = delete;
312 
313  __hashtable_alloc* _M_h;
314  __node_ptr _M_node;
315  };
316 
317  template<typename _Ht>
318  static constexpr
319  typename conditional<std::is_lvalue_reference<_Ht>::value,
320  const value_type&, value_type&&>::type
321  __fwd_value_for(value_type& __val) noexcept
322  { return std::move(__val); }
323 
324  // Compile-time diagnostics.
325 
326  // _Hash_code_base has everything protected, so use this derived type to
327  // access it.
328  struct __hash_code_base_access : __hash_code_base
329  { using __hash_code_base::_M_bucket_index; };
330 
331  // Getting a bucket index from a node shall not throw because it is used
332  // in methods (erase, swap...) that shall not throw.
333  static_assert(noexcept(declval<const __hash_code_base_access&>()
334  ._M_bucket_index(declval<const __node_value_type&>(),
335  (std::size_t)0)),
336  "Cache the hash code or qualify your functors involved"
337  " in hash code and bucket index computation with noexcept");
338 
339  // To get bucket index we need _RangeHash not to throw.
340  static_assert(is_nothrow_default_constructible<_RangeHash>::value,
341  "Functor used to map hash code to bucket index"
342  " must be nothrow default constructible");
343  static_assert(noexcept(
344  std::declval<const _RangeHash&>()((std::size_t)0, (std::size_t)0)),
345  "Functor used to map hash code to bucket index must be"
346  " noexcept");
347 
348  // To compute bucket index we also need _ExtratKey not to throw.
349  static_assert(is_nothrow_default_constructible<_ExtractKey>::value,
350  "_ExtractKey must be nothrow default constructible");
351  static_assert(noexcept(
352  std::declval<const _ExtractKey&>()(std::declval<_Value>())),
353  "_ExtractKey functor must be noexcept invocable");
354 
355  template<typename _Keya, typename _Valuea, typename _Alloca,
356  typename _ExtractKeya, typename _Equala,
357  typename _Hasha, typename _RangeHasha, typename _Unuseda,
358  typename _RehashPolicya, typename _Traitsa,
359  bool _Unique_keysa>
360  friend struct __detail::_Map_base;
361 
362  template<typename _Keya, typename _Valuea, typename _Alloca,
363  typename _ExtractKeya, typename _Equala,
364  typename _Hasha, typename _RangeHasha, typename _Unuseda,
365  typename _RehashPolicya, typename _Traitsa>
366  friend struct __detail::_Insert_base;
367 
368  template<typename _Keya, typename _Valuea, typename _Alloca,
369  typename _ExtractKeya, typename _Equala,
370  typename _Hasha, typename _RangeHasha, typename _Unuseda,
371  typename _RehashPolicya, typename _Traitsa,
372  bool _Constant_iteratorsa>
373  friend struct __detail::_Insert;
374 
375  template<typename _Keya, typename _Valuea, typename _Alloca,
376  typename _ExtractKeya, typename _Equala,
377  typename _Hasha, typename _RangeHasha, typename _Unuseda,
378  typename _RehashPolicya, typename _Traitsa,
379  bool _Unique_keysa>
380  friend struct __detail::_Equality;
381 
382  public:
383  using size_type = typename __hashtable_base::size_type;
384  using difference_type = typename __hashtable_base::difference_type;
385 
386 #if __cplusplus > 201402L
387  using node_type = _Node_handle<_Key, _Value, __node_alloc_type>;
388  using insert_return_type = _Node_insert_return<iterator, node_type>;
389 #endif
390 
391  private:
392  __buckets_ptr _M_buckets = &_M_single_bucket;
393  size_type _M_bucket_count = 1;
394  __node_base _M_before_begin;
395  size_type _M_element_count = 0;
396  _RehashPolicy _M_rehash_policy;
397 
398  // A single bucket used when only need for 1 bucket. Especially
399  // interesting in move semantic to leave hashtable with only 1 bucket
400  // which is not allocated so that we can have those operations noexcept
401  // qualified.
402  // Note that we can't leave hashtable with 0 bucket without adding
403  // numerous checks in the code to avoid 0 modulus.
404  __node_base_ptr _M_single_bucket = nullptr;
405 
406  void
407  _M_update_bbegin()
408  {
409  if (_M_begin())
410  _M_buckets[_M_bucket_index(*_M_begin())] = &_M_before_begin;
411  }
412 
413  void
414  _M_update_bbegin(__node_ptr __n)
415  {
416  _M_before_begin._M_nxt = __n;
417  _M_update_bbegin();
418  }
419 
420  bool
421  _M_uses_single_bucket(__buckets_ptr __bkts) const
422  { return __builtin_expect(__bkts == &_M_single_bucket, false); }
423 
424  bool
425  _M_uses_single_bucket() const
426  { return _M_uses_single_bucket(_M_buckets); }
427 
428  __hashtable_alloc&
429  _M_base_alloc() { return *this; }
430 
431  __buckets_ptr
432  _M_allocate_buckets(size_type __bkt_count)
433  {
434  if (__builtin_expect(__bkt_count == 1, false))
435  {
436  _M_single_bucket = nullptr;
437  return &_M_single_bucket;
438  }
439 
440  return __hashtable_alloc::_M_allocate_buckets(__bkt_count);
441  }
442 
443  void
444  _M_deallocate_buckets(__buckets_ptr __bkts, size_type __bkt_count)
445  {
446  if (_M_uses_single_bucket(__bkts))
447  return;
448 
449  __hashtable_alloc::_M_deallocate_buckets(__bkts, __bkt_count);
450  }
451 
452  void
453  _M_deallocate_buckets()
454  { _M_deallocate_buckets(_M_buckets, _M_bucket_count); }
455 
456  // Gets bucket begin, deals with the fact that non-empty buckets contain
457  // their before begin node.
458  __node_ptr
459  _M_bucket_begin(size_type __bkt) const;
460 
461  __node_ptr
462  _M_begin() const
463  { return static_cast<__node_ptr>(_M_before_begin._M_nxt); }
464 
465  // Assign *this using another _Hashtable instance. Whether elements
466  // are copied or moved depends on the _Ht reference.
467  template<typename _Ht>
468  void
469  _M_assign_elements(_Ht&&);
470 
471  template<typename _Ht, typename _NodeGenerator>
472  void
473  _M_assign(_Ht&&, const _NodeGenerator&);
474 
475  void
476  _M_move_assign(_Hashtable&&, true_type);
477 
478  void
479  _M_move_assign(_Hashtable&&, false_type);
480 
481  void
482  _M_reset() noexcept;
483 
484  _Hashtable(const _Hash& __h, const _Equal& __eq,
485  const allocator_type& __a)
486  : __hashtable_base(__h, __eq),
487  __hashtable_alloc(__node_alloc_type(__a)),
488  __enable_default_ctor(_Enable_default_constructor_tag{})
489  { }
490 
491  template<bool _No_realloc = true>
492  static constexpr bool
493  _S_nothrow_move()
494  {
495 #if __cplusplus <= 201402L
496  return __and_<__bool_constant<_No_realloc>,
497  is_nothrow_copy_constructible<_Hash>,
498  is_nothrow_copy_constructible<_Equal>>::value;
499 #else
500  if constexpr (_No_realloc)
501  if constexpr (is_nothrow_copy_constructible<_Hash>())
502  return is_nothrow_copy_constructible<_Equal>();
503  return false;
504 #endif
505  }
506 
507  _Hashtable(_Hashtable&& __ht, __node_alloc_type&& __a,
508  true_type /* alloc always equal */)
509  noexcept(_S_nothrow_move());
510 
511  _Hashtable(_Hashtable&&, __node_alloc_type&&,
512  false_type /* alloc always equal */);
513 
514  template<typename _InputIterator>
515  _Hashtable(_InputIterator __first, _InputIterator __last,
516  size_type __bkt_count_hint,
517  const _Hash&, const _Equal&, const allocator_type&,
518  true_type __uks);
519 
520  template<typename _InputIterator>
521  _Hashtable(_InputIterator __first, _InputIterator __last,
522  size_type __bkt_count_hint,
523  const _Hash&, const _Equal&, const allocator_type&,
524  false_type __uks);
525 
526  public:
527  // Constructor, destructor, assignment, swap
528  _Hashtable() = default;
529 
530  _Hashtable(const _Hashtable&);
531 
532  _Hashtable(const _Hashtable&, const allocator_type&);
533 
534  explicit
535  _Hashtable(size_type __bkt_count_hint,
536  const _Hash& __hf = _Hash(),
537  const key_equal& __eql = key_equal(),
538  const allocator_type& __a = allocator_type());
539 
540  // Use delegating constructors.
541  _Hashtable(_Hashtable&& __ht)
542  noexcept(_S_nothrow_move())
543  : _Hashtable(std::move(__ht), std::move(__ht._M_node_allocator()),
544  true_type{})
545  { }
546 
547  _Hashtable(_Hashtable&& __ht, const allocator_type& __a)
548  noexcept(_S_nothrow_move<__node_alloc_traits::_S_always_equal()>())
549  : _Hashtable(std::move(__ht), __node_alloc_type(__a),
550  typename __node_alloc_traits::is_always_equal{})
551  { }
552 
553  explicit
554  _Hashtable(const allocator_type& __a)
555  : __hashtable_alloc(__node_alloc_type(__a)),
556  __enable_default_ctor(_Enable_default_constructor_tag{})
557  { }
558 
559  template<typename _InputIterator>
560  _Hashtable(_InputIterator __f, _InputIterator __l,
561  size_type __bkt_count_hint = 0,
562  const _Hash& __hf = _Hash(),
563  const key_equal& __eql = key_equal(),
564  const allocator_type& __a = allocator_type())
565  : _Hashtable(__f, __l, __bkt_count_hint, __hf, __eql, __a,
566  __unique_keys{})
567  { }
568 
569  _Hashtable(initializer_list<value_type> __l,
570  size_type __bkt_count_hint = 0,
571  const _Hash& __hf = _Hash(),
572  const key_equal& __eql = key_equal(),
573  const allocator_type& __a = allocator_type())
574  : _Hashtable(__l.begin(), __l.end(), __bkt_count_hint,
575  __hf, __eql, __a, __unique_keys{})
576  { }
577 
578  _Hashtable&
579  operator=(const _Hashtable& __ht);
580 
581  _Hashtable&
582  operator=(_Hashtable&& __ht)
583  noexcept(__node_alloc_traits::_S_nothrow_move()
584  && is_nothrow_move_assignable<_Hash>::value
585  && is_nothrow_move_assignable<_Equal>::value)
586  {
587  constexpr bool __move_storage =
588  __node_alloc_traits::_S_propagate_on_move_assign()
589  || __node_alloc_traits::_S_always_equal();
590  _M_move_assign(std::move(__ht), __bool_constant<__move_storage>());
591  return *this;
592  }
593 
594  _Hashtable&
595  operator=(initializer_list<value_type> __l)
596  {
597  __reuse_or_alloc_node_gen_t __roan(_M_begin(), *this);
598  _M_before_begin._M_nxt = nullptr;
599  clear();
600 
601  // We consider that all elements of __l are going to be inserted.
602  auto __l_bkt_count = _M_rehash_policy._M_bkt_for_elements(__l.size());
603 
604  // Do not shrink to keep potential user reservation.
605  if (_M_bucket_count < __l_bkt_count)
606  rehash(__l_bkt_count);
607 
608  this->_M_insert_range(__l.begin(), __l.end(), __roan, __unique_keys{});
609  return *this;
610  }
611 
612  ~_Hashtable() noexcept;
613 
614  void
615  swap(_Hashtable&)
616  noexcept(__and_<__is_nothrow_swappable<_Hash>,
617  __is_nothrow_swappable<_Equal>>::value);
618 
619  // Basic container operations
620  iterator
621  begin() noexcept
622  { return iterator(_M_begin()); }
623 
624  const_iterator
625  begin() const noexcept
626  { return const_iterator(_M_begin()); }
627 
628  iterator
629  end() noexcept
630  { return iterator(nullptr); }
631 
632  const_iterator
633  end() const noexcept
634  { return const_iterator(nullptr); }
635 
636  const_iterator
637  cbegin() const noexcept
638  { return const_iterator(_M_begin()); }
639 
640  const_iterator
641  cend() const noexcept
642  { return const_iterator(nullptr); }
643 
644  size_type
645  size() const noexcept
646  { return _M_element_count; }
647 
648  _GLIBCXX_NODISCARD bool
649  empty() const noexcept
650  { return size() == 0; }
651 
652  allocator_type
653  get_allocator() const noexcept
654  { return allocator_type(this->_M_node_allocator()); }
655 
656  size_type
657  max_size() const noexcept
658  { return __node_alloc_traits::max_size(this->_M_node_allocator()); }
659 
660  // Observers
661  key_equal
662  key_eq() const
663  { return this->_M_eq(); }
664 
665  // hash_function, if present, comes from _Hash_code_base.
666 
667  // Bucket operations
668  size_type
669  bucket_count() const noexcept
670  { return _M_bucket_count; }
671 
672  size_type
673  max_bucket_count() const noexcept
674  { return max_size(); }
675 
676  size_type
677  bucket_size(size_type __bkt) const
678  { return std::distance(begin(__bkt), end(__bkt)); }
679 
680  size_type
681  bucket(const key_type& __k) const
682  { return _M_bucket_index(this->_M_hash_code(__k)); }
683 
684  local_iterator
685  begin(size_type __bkt)
686  {
687  return local_iterator(*this, _M_bucket_begin(__bkt),
688  __bkt, _M_bucket_count);
689  }
690 
691  local_iterator
692  end(size_type __bkt)
693  { return local_iterator(*this, nullptr, __bkt, _M_bucket_count); }
694 
695  const_local_iterator
696  begin(size_type __bkt) const
697  {
698  return const_local_iterator(*this, _M_bucket_begin(__bkt),
699  __bkt, _M_bucket_count);
700  }
701 
702  const_local_iterator
703  end(size_type __bkt) const
704  { return const_local_iterator(*this, nullptr, __bkt, _M_bucket_count); }
705 
706  // DR 691.
707  const_local_iterator
708  cbegin(size_type __bkt) const
709  {
710  return const_local_iterator(*this, _M_bucket_begin(__bkt),
711  __bkt, _M_bucket_count);
712  }
713 
714  const_local_iterator
715  cend(size_type __bkt) const
716  { return const_local_iterator(*this, nullptr, __bkt, _M_bucket_count); }
717 
718  float
719  load_factor() const noexcept
720  {
721  return static_cast<float>(size()) / static_cast<float>(bucket_count());
722  }
723 
724  // max_load_factor, if present, comes from _Rehash_base.
725 
726  // Generalization of max_load_factor. Extension, not found in
727  // TR1. Only useful if _RehashPolicy is something other than
728  // the default.
729  const _RehashPolicy&
730  __rehash_policy() const
731  { return _M_rehash_policy; }
732 
733  void
734  __rehash_policy(const _RehashPolicy& __pol)
735  { _M_rehash_policy = __pol; }
736 
737  // Lookup.
738  iterator
739  find(const key_type& __k);
740 
741  const_iterator
742  find(const key_type& __k) const;
743 
744  size_type
745  count(const key_type& __k) const;
746 
748  equal_range(const key_type& __k);
749 
751  equal_range(const key_type& __k) const;
752 
753 #if __cplusplus >= 202002L
754 #define __cpp_lib_generic_unordered_lookup 201811L
755 
756  template<typename _Kt,
757  typename = __has_is_transparent_t<_Hash, _Kt>,
758  typename = __has_is_transparent_t<_Equal, _Kt>>
759  iterator
760  _M_find_tr(const _Kt& __k);
761 
762  template<typename _Kt,
763  typename = __has_is_transparent_t<_Hash, _Kt>,
764  typename = __has_is_transparent_t<_Equal, _Kt>>
765  const_iterator
766  _M_find_tr(const _Kt& __k) const;
767 
768  template<typename _Kt,
769  typename = __has_is_transparent_t<_Hash, _Kt>,
770  typename = __has_is_transparent_t<_Equal, _Kt>>
771  size_type
772  _M_count_tr(const _Kt& __k) const;
773 
774  template<typename _Kt,
775  typename = __has_is_transparent_t<_Hash, _Kt>,
776  typename = __has_is_transparent_t<_Equal, _Kt>>
777  pair<iterator, iterator>
778  _M_equal_range_tr(const _Kt& __k);
779 
780  template<typename _Kt,
781  typename = __has_is_transparent_t<_Hash, _Kt>,
782  typename = __has_is_transparent_t<_Equal, _Kt>>
783  pair<const_iterator, const_iterator>
784  _M_equal_range_tr(const _Kt& __k) const;
785 #endif // C++20
786 
787  private:
788  // Bucket index computation helpers.
789  size_type
790  _M_bucket_index(const __node_value_type& __n) const noexcept
791  { return __hash_code_base::_M_bucket_index(__n, _M_bucket_count); }
792 
793  size_type
794  _M_bucket_index(__hash_code __c) const
795  { return __hash_code_base::_M_bucket_index(__c, _M_bucket_count); }
796 
797  // Find and insert helper functions and types
798  // Find the node before the one matching the criteria.
799  __node_base_ptr
800  _M_find_before_node(size_type, const key_type&, __hash_code) const;
801 
802  template<typename _Kt>
803  __node_base_ptr
804  _M_find_before_node_tr(size_type, const _Kt&, __hash_code) const;
805 
806  __node_ptr
807  _M_find_node(size_type __bkt, const key_type& __key,
808  __hash_code __c) const
809  {
810  __node_base_ptr __before_n = _M_find_before_node(__bkt, __key, __c);
811  if (__before_n)
812  return static_cast<__node_ptr>(__before_n->_M_nxt);
813  return nullptr;
814  }
815 
816  template<typename _Kt>
817  __node_ptr
818  _M_find_node_tr(size_type __bkt, const _Kt& __key,
819  __hash_code __c) const
820  {
821  auto __before_n = _M_find_before_node_tr(__bkt, __key, __c);
822  if (__before_n)
823  return static_cast<__node_ptr>(__before_n->_M_nxt);
824  return nullptr;
825  }
826 
827  // Insert a node at the beginning of a bucket.
828  void
829  _M_insert_bucket_begin(size_type, __node_ptr);
830 
831  // Remove the bucket first node
832  void
833  _M_remove_bucket_begin(size_type __bkt, __node_ptr __next_n,
834  size_type __next_bkt);
835 
836  // Get the node before __n in the bucket __bkt
837  __node_base_ptr
838  _M_get_previous_node(size_type __bkt, __node_ptr __n);
839 
840  // Insert node __n with hash code __code, in bucket __bkt if no
841  // rehash (assumes no element with same key already present).
842  // Takes ownership of __n if insertion succeeds, throws otherwise.
843  iterator
844  _M_insert_unique_node(size_type __bkt, __hash_code,
845  __node_ptr __n, size_type __n_elt = 1);
846 
847  // Insert node __n with key __k and hash code __code.
848  // Takes ownership of __n if insertion succeeds, throws otherwise.
849  iterator
850  _M_insert_multi_node(__node_ptr __hint,
851  __hash_code __code, __node_ptr __n);
852 
853  template<typename... _Args>
855  _M_emplace(true_type __uks, _Args&&... __args);
856 
857  template<typename... _Args>
858  iterator
859  _M_emplace(false_type __uks, _Args&&... __args)
860  { return _M_emplace(cend(), __uks, std::forward<_Args>(__args)...); }
861 
862  // Emplace with hint, useless when keys are unique.
863  template<typename... _Args>
864  iterator
865  _M_emplace(const_iterator, true_type __uks, _Args&&... __args)
866  { return _M_emplace(__uks, std::forward<_Args>(__args)...).first; }
867 
868  template<typename... _Args>
869  iterator
870  _M_emplace(const_iterator, false_type __uks, _Args&&... __args);
871 
872  template<typename _Arg, typename _NodeGenerator>
874  _M_insert(_Arg&&, const _NodeGenerator&, true_type __uks);
875 
876  template<typename _Arg, typename _NodeGenerator>
877  iterator
878  _M_insert(_Arg&& __arg, const _NodeGenerator& __node_gen,
879  false_type __uks)
880  {
881  return _M_insert(cend(), std::forward<_Arg>(__arg), __node_gen,
882  __uks);
883  }
884 
885  // Insert with hint, not used when keys are unique.
886  template<typename _Arg, typename _NodeGenerator>
887  iterator
888  _M_insert(const_iterator, _Arg&& __arg,
889  const _NodeGenerator& __node_gen, true_type __uks)
890  {
891  return
892  _M_insert(std::forward<_Arg>(__arg), __node_gen, __uks).first;
893  }
894 
895  // Insert with hint when keys are not unique.
896  template<typename _Arg, typename _NodeGenerator>
897  iterator
898  _M_insert(const_iterator, _Arg&&,
899  const _NodeGenerator&, false_type __uks);
900 
901  size_type
902  _M_erase(true_type __uks, const key_type&);
903 
904  size_type
905  _M_erase(false_type __uks, const key_type&);
906 
907  iterator
908  _M_erase(size_type __bkt, __node_base_ptr __prev_n, __node_ptr __n);
909 
910  public:
911  // Emplace
912  template<typename... _Args>
913  __ireturn_type
914  emplace(_Args&&... __args)
915  { return _M_emplace(__unique_keys{}, std::forward<_Args>(__args)...); }
916 
917  template<typename... _Args>
918  iterator
919  emplace_hint(const_iterator __hint, _Args&&... __args)
920  {
921  return _M_emplace(__hint, __unique_keys{},
922  std::forward<_Args>(__args)...);
923  }
924 
925  // Insert member functions via inheritance.
926 
927  // Erase
928  iterator
929  erase(const_iterator);
930 
931  // LWG 2059.
932  iterator
933  erase(iterator __it)
934  { return erase(const_iterator(__it)); }
935 
936  size_type
937  erase(const key_type& __k)
938  { return _M_erase(__unique_keys{}, __k); }
939 
940  iterator
941  erase(const_iterator, const_iterator);
942 
943  void
944  clear() noexcept;
945 
946  // Set number of buckets keeping it appropriate for container's number
947  // of elements.
948  void rehash(size_type __bkt_count);
949 
950  // DR 1189.
951  // reserve, if present, comes from _Rehash_base.
952 
953 #if __cplusplus > 201402L
954  /// Re-insert an extracted node into a container with unique keys.
955  insert_return_type
956  _M_reinsert_node(node_type&& __nh)
957  {
958  insert_return_type __ret;
959  if (__nh.empty())
960  __ret.position = end();
961  else
962  {
963  __glibcxx_assert(get_allocator() == __nh.get_allocator());
964 
965  const key_type& __k = __nh._M_key();
966  __hash_code __code = this->_M_hash_code(__k);
967  size_type __bkt = _M_bucket_index(__code);
968  if (__node_ptr __n = _M_find_node(__bkt, __k, __code))
969  {
970  __ret.node = std::move(__nh);
971  __ret.position = iterator(__n);
972  __ret.inserted = false;
973  }
974  else
975  {
976  __ret.position
977  = _M_insert_unique_node(__bkt, __code, __nh._M_ptr);
978  __nh._M_ptr = nullptr;
979  __ret.inserted = true;
980  }
981  }
982  return __ret;
983  }
984 
985  /// Re-insert an extracted node into a container with equivalent keys.
986  iterator
987  _M_reinsert_node_multi(const_iterator __hint, node_type&& __nh)
988  {
989  if (__nh.empty())
990  return end();
991 
992  __glibcxx_assert(get_allocator() == __nh.get_allocator());
993 
994  const key_type& __k = __nh._M_key();
995  auto __code = this->_M_hash_code(__k);
996  auto __ret
997  = _M_insert_multi_node(__hint._M_cur, __code, __nh._M_ptr);
998  __nh._M_ptr = nullptr;
999  return __ret;
1000  }
1001 
1002  private:
1003  node_type
1004  _M_extract_node(size_t __bkt, __node_base_ptr __prev_n)
1005  {
1006  __node_ptr __n = static_cast<__node_ptr>(__prev_n->_M_nxt);
1007  if (__prev_n == _M_buckets[__bkt])
1008  _M_remove_bucket_begin(__bkt, __n->_M_next(),
1009  __n->_M_nxt ? _M_bucket_index(*__n->_M_next()) : 0);
1010  else if (__n->_M_nxt)
1011  {
1012  size_type __next_bkt = _M_bucket_index(*__n->_M_next());
1013  if (__next_bkt != __bkt)
1014  _M_buckets[__next_bkt] = __prev_n;
1015  }
1016 
1017  __prev_n->_M_nxt = __n->_M_nxt;
1018  __n->_M_nxt = nullptr;
1019  --_M_element_count;
1020  return { __n, this->_M_node_allocator() };
1021  }
1022 
1023  public:
1024  // Extract a node.
1025  node_type
1026  extract(const_iterator __pos)
1027  {
1028  size_t __bkt = _M_bucket_index(*__pos._M_cur);
1029  return _M_extract_node(__bkt,
1030  _M_get_previous_node(__bkt, __pos._M_cur));
1031  }
1032 
1033  /// Extract a node.
1034  node_type
1035  extract(const _Key& __k)
1036  {
1037  node_type __nh;
1038  __hash_code __code = this->_M_hash_code(__k);
1039  std::size_t __bkt = _M_bucket_index(__code);
1040  if (__node_base_ptr __prev_node = _M_find_before_node(__bkt, __k, __code))
1041  __nh = _M_extract_node(__bkt, __prev_node);
1042  return __nh;
1043  }
1044 
1045  /// Merge from a compatible container into one with unique keys.
1046  template<typename _Compatible_Hashtable>
1047  void
1048  _M_merge_unique(_Compatible_Hashtable& __src) noexcept
1049  {
1050  static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
1051  node_type>, "Node types are compatible");
1052  __glibcxx_assert(get_allocator() == __src.get_allocator());
1053 
1054  auto __n_elt = __src.size();
1055  for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
1056  {
1057  auto __pos = __i++;
1058  const key_type& __k = _ExtractKey{}(*__pos);
1059  __hash_code __code = this->_M_hash_code(__k);
1060  size_type __bkt = _M_bucket_index(__code);
1061  if (_M_find_node(__bkt, __k, __code) == nullptr)
1062  {
1063  auto __nh = __src.extract(__pos);
1064  _M_insert_unique_node(__bkt, __code, __nh._M_ptr, __n_elt);
1065  __nh._M_ptr = nullptr;
1066  __n_elt = 1;
1067  }
1068  else if (__n_elt != 1)
1069  --__n_elt;
1070  }
1071  }
1072 
1073  /// Merge from a compatible container into one with equivalent keys.
1074  template<typename _Compatible_Hashtable>
1075  void
1076  _M_merge_multi(_Compatible_Hashtable& __src) noexcept
1077  {
1078  static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
1079  node_type>, "Node types are compatible");
1080  __glibcxx_assert(get_allocator() == __src.get_allocator());
1081 
1082  this->reserve(size() + __src.size());
1083  for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
1084  _M_reinsert_node_multi(cend(), __src.extract(__i++));
1085  }
1086 #endif // C++17
1087 
1088  private:
1089  // Helper rehash method used when keys are unique.
1090  void _M_rehash_aux(size_type __bkt_count, true_type __uks);
1091 
1092  // Helper rehash method used when keys can be non-unique.
1093  void _M_rehash_aux(size_type __bkt_count, false_type __uks);
1094 
1095  // Unconditionally change size of bucket array to n, restore
1096  // hash policy state to __state on exception.
1097  void _M_rehash(size_type __bkt_count, const __rehash_state& __state);
1098  };
1099 
1100 
1101  // Definitions of class template _Hashtable's out-of-line member functions.
1102  template<typename _Key, typename _Value, typename _Alloc,
1103  typename _ExtractKey, typename _Equal,
1104  typename _Hash, typename _RangeHash, typename _Unused,
1105  typename _RehashPolicy, typename _Traits>
1106  auto
1107  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1108  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1109  _M_bucket_begin(size_type __bkt) const
1110  -> __node_ptr
1111  {
1112  __node_base_ptr __n = _M_buckets[__bkt];
1113  return __n ? static_cast<__node_ptr>(__n->_M_nxt) : nullptr;
1114  }
1115 
1116  template<typename _Key, typename _Value, typename _Alloc,
1117  typename _ExtractKey, typename _Equal,
1118  typename _Hash, typename _RangeHash, typename _Unused,
1119  typename _RehashPolicy, typename _Traits>
1120  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1121  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1122  _Hashtable(size_type __bkt_count_hint,
1123  const _Hash& __h, const _Equal& __eq, const allocator_type& __a)
1124  : _Hashtable(__h, __eq, __a)
1125  {
1126  auto __bkt_count = _M_rehash_policy._M_next_bkt(__bkt_count_hint);
1127  if (__bkt_count > _M_bucket_count)
1128  {
1129  _M_buckets = _M_allocate_buckets(__bkt_count);
1130  _M_bucket_count = __bkt_count;
1131  }
1132  }
1133 
1134  template<typename _Key, typename _Value, typename _Alloc,
1135  typename _ExtractKey, typename _Equal,
1136  typename _Hash, typename _RangeHash, typename _Unused,
1137  typename _RehashPolicy, typename _Traits>
1138  template<typename _InputIterator>
1139  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1140  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1141  _Hashtable(_InputIterator __f, _InputIterator __l,
1142  size_type __bkt_count_hint,
1143  const _Hash& __h, const _Equal& __eq,
1144  const allocator_type& __a, true_type /* __uks */)
1145  : _Hashtable(__bkt_count_hint, __h, __eq, __a)
1146  {
1147  for (; __f != __l; ++__f)
1148  this->insert(*__f);
1149  }
1150 
1151  template<typename _Key, typename _Value, typename _Alloc,
1152  typename _ExtractKey, typename _Equal,
1153  typename _Hash, typename _RangeHash, typename _Unused,
1154  typename _RehashPolicy, typename _Traits>
1155  template<typename _InputIterator>
1156  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1157  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1158  _Hashtable(_InputIterator __f, _InputIterator __l,
1159  size_type __bkt_count_hint,
1160  const _Hash& __h, const _Equal& __eq,
1161  const allocator_type& __a, false_type /* __uks */)
1162  : _Hashtable(__h, __eq, __a)
1163  {
1164  auto __nb_elems = __detail::__distance_fw(__f, __l);
1165  auto __bkt_count =
1166  _M_rehash_policy._M_next_bkt(
1167  std::max(_M_rehash_policy._M_bkt_for_elements(__nb_elems),
1168  __bkt_count_hint));
1169 
1170  if (__bkt_count > _M_bucket_count)
1171  {
1172  _M_buckets = _M_allocate_buckets(__bkt_count);
1173  _M_bucket_count = __bkt_count;
1174  }
1175 
1176  for (; __f != __l; ++__f)
1177  this->insert(*__f);
1178  }
1179 
1180  template<typename _Key, typename _Value, typename _Alloc,
1181  typename _ExtractKey, typename _Equal,
1182  typename _Hash, typename _RangeHash, typename _Unused,
1183  typename _RehashPolicy, typename _Traits>
1184  auto
1185  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1186  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1187  operator=(const _Hashtable& __ht)
1188  -> _Hashtable&
1189  {
1190  if (&__ht == this)
1191  return *this;
1192 
1193  if (__node_alloc_traits::_S_propagate_on_copy_assign())
1194  {
1195  auto& __this_alloc = this->_M_node_allocator();
1196  auto& __that_alloc = __ht._M_node_allocator();
1197  if (!__node_alloc_traits::_S_always_equal()
1198  && __this_alloc != __that_alloc)
1199  {
1200  // Replacement allocator cannot free existing storage.
1201  this->_M_deallocate_nodes(_M_begin());
1202  _M_before_begin._M_nxt = nullptr;
1203  _M_deallocate_buckets();
1204  _M_buckets = nullptr;
1205  std::__alloc_on_copy(__this_alloc, __that_alloc);
1206  __hashtable_base::operator=(__ht);
1207  _M_bucket_count = __ht._M_bucket_count;
1208  _M_element_count = __ht._M_element_count;
1209  _M_rehash_policy = __ht._M_rehash_policy;
1210  __alloc_node_gen_t __alloc_node_gen(*this);
1211  __try
1212  {
1213  _M_assign(__ht, __alloc_node_gen);
1214  }
1215  __catch(...)
1216  {
1217  // _M_assign took care of deallocating all memory. Now we
1218  // must make sure this instance remains in a usable state.
1219  _M_reset();
1220  __throw_exception_again;
1221  }
1222  return *this;
1223  }
1224  std::__alloc_on_copy(__this_alloc, __that_alloc);
1225  }
1226 
1227  // Reuse allocated buckets and nodes.
1228  _M_assign_elements(__ht);
1229  return *this;
1230  }
1231 
1232  template<typename _Key, typename _Value, typename _Alloc,
1233  typename _ExtractKey, typename _Equal,
1234  typename _Hash, typename _RangeHash, typename _Unused,
1235  typename _RehashPolicy, typename _Traits>
1236  template<typename _Ht>
1237  void
1238  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1239  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1240  _M_assign_elements(_Ht&& __ht)
1241  {
1242  __buckets_ptr __former_buckets = nullptr;
1243  std::size_t __former_bucket_count = _M_bucket_count;
1244  const __rehash_state& __former_state = _M_rehash_policy._M_state();
1245 
1246  if (_M_bucket_count != __ht._M_bucket_count)
1247  {
1248  __former_buckets = _M_buckets;
1249  _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
1250  _M_bucket_count = __ht._M_bucket_count;
1251  }
1252  else
1253  __builtin_memset(_M_buckets, 0,
1254  _M_bucket_count * sizeof(__node_base_ptr));
1255 
1256  __try
1257  {
1258  __hashtable_base::operator=(std::forward<_Ht>(__ht));
1259  _M_element_count = __ht._M_element_count;
1260  _M_rehash_policy = __ht._M_rehash_policy;
1261  __reuse_or_alloc_node_gen_t __roan(_M_begin(), *this);
1262  _M_before_begin._M_nxt = nullptr;
1263  _M_assign(std::forward<_Ht>(__ht), __roan);
1264  if (__former_buckets)
1265  _M_deallocate_buckets(__former_buckets, __former_bucket_count);
1266  }
1267  __catch(...)
1268  {
1269  if (__former_buckets)
1270  {
1271  // Restore previous buckets.
1272  _M_deallocate_buckets();
1273  _M_rehash_policy._M_reset(__former_state);
1274  _M_buckets = __former_buckets;
1275  _M_bucket_count = __former_bucket_count;
1276  }
1277  __builtin_memset(_M_buckets, 0,
1278  _M_bucket_count * sizeof(__node_base_ptr));
1279  __throw_exception_again;
1280  }
1281  }
1282 
1283  template<typename _Key, typename _Value, typename _Alloc,
1284  typename _ExtractKey, typename _Equal,
1285  typename _Hash, typename _RangeHash, typename _Unused,
1286  typename _RehashPolicy, typename _Traits>
1287  template<typename _Ht, typename _NodeGenerator>
1288  void
1289  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1290  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1291  _M_assign(_Ht&& __ht, const _NodeGenerator& __node_gen)
1292  {
1293  __buckets_ptr __buckets = nullptr;
1294  if (!_M_buckets)
1295  _M_buckets = __buckets = _M_allocate_buckets(_M_bucket_count);
1296 
1297  __try
1298  {
1299  if (!__ht._M_before_begin._M_nxt)
1300  return;
1301 
1302  // First deal with the special first node pointed to by
1303  // _M_before_begin.
1304  __node_ptr __ht_n = __ht._M_begin();
1305  __node_ptr __this_n
1306  = __node_gen(__fwd_value_for<_Ht>(__ht_n->_M_v()));
1307  this->_M_copy_code(*__this_n, *__ht_n);
1308  _M_update_bbegin(__this_n);
1309 
1310  // Then deal with other nodes.
1311  __node_ptr __prev_n = __this_n;
1312  for (__ht_n = __ht_n->_M_next(); __ht_n; __ht_n = __ht_n->_M_next())
1313  {
1314  __this_n = __node_gen(__fwd_value_for<_Ht>(__ht_n->_M_v()));
1315  __prev_n->_M_nxt = __this_n;
1316  this->_M_copy_code(*__this_n, *__ht_n);
1317  size_type __bkt = _M_bucket_index(*__this_n);
1318  if (!_M_buckets[__bkt])
1319  _M_buckets[__bkt] = __prev_n;
1320  __prev_n = __this_n;
1321  }
1322  }
1323  __catch(...)
1324  {
1325  clear();
1326  if (__buckets)
1327  _M_deallocate_buckets();
1328  __throw_exception_again;
1329  }
1330  }
1331 
1332  template<typename _Key, typename _Value, typename _Alloc,
1333  typename _ExtractKey, typename _Equal,
1334  typename _Hash, typename _RangeHash, typename _Unused,
1335  typename _RehashPolicy, typename _Traits>
1336  void
1337  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1338  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1339  _M_reset() noexcept
1340  {
1341  _M_rehash_policy._M_reset();
1342  _M_bucket_count = 1;
1343  _M_single_bucket = nullptr;
1344  _M_buckets = &_M_single_bucket;
1345  _M_before_begin._M_nxt = nullptr;
1346  _M_element_count = 0;
1347  }
1348 
1349  template<typename _Key, typename _Value, typename _Alloc,
1350  typename _ExtractKey, typename _Equal,
1351  typename _Hash, typename _RangeHash, typename _Unused,
1352  typename _RehashPolicy, typename _Traits>
1353  void
1354  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1355  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1356  _M_move_assign(_Hashtable&& __ht, true_type)
1357  {
1358  if (__builtin_expect(std::__addressof(__ht) == this, false))
1359  return;
1360 
1361  this->_M_deallocate_nodes(_M_begin());
1362  _M_deallocate_buckets();
1363  __hashtable_base::operator=(std::move(__ht));
1364  _M_rehash_policy = __ht._M_rehash_policy;
1365  if (!__ht._M_uses_single_bucket())
1366  _M_buckets = __ht._M_buckets;
1367  else
1368  {
1369  _M_buckets = &_M_single_bucket;
1370  _M_single_bucket = __ht._M_single_bucket;
1371  }
1372 
1373  _M_bucket_count = __ht._M_bucket_count;
1374  _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
1375  _M_element_count = __ht._M_element_count;
1376  std::__alloc_on_move(this->_M_node_allocator(), __ht._M_node_allocator());
1377 
1378  // Fix bucket containing the _M_before_begin pointer that can't be moved.
1379  _M_update_bbegin();
1380  __ht._M_reset();
1381  }
1382 
1383  template<typename _Key, typename _Value, typename _Alloc,
1384  typename _ExtractKey, typename _Equal,
1385  typename _Hash, typename _RangeHash, typename _Unused,
1386  typename _RehashPolicy, typename _Traits>
1387  void
1388  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1389  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1390  _M_move_assign(_Hashtable&& __ht, false_type)
1391  {
1392  if (__ht._M_node_allocator() == this->_M_node_allocator())
1393  _M_move_assign(std::move(__ht), true_type{});
1394  else
1395  {
1396  // Can't move memory, move elements then.
1397  _M_assign_elements(std::move(__ht));
1398  __ht.clear();
1399  }
1400  }
1401 
1402  template<typename _Key, typename _Value, typename _Alloc,
1403  typename _ExtractKey, typename _Equal,
1404  typename _Hash, typename _RangeHash, typename _Unused,
1405  typename _RehashPolicy, typename _Traits>
1406  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1407  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1408  _Hashtable(const _Hashtable& __ht)
1409  : __hashtable_base(__ht),
1410  __map_base(__ht),
1411  __rehash_base(__ht),
1412  __hashtable_alloc(
1413  __node_alloc_traits::_S_select_on_copy(__ht._M_node_allocator())),
1414  __enable_default_ctor(__ht),
1415  _M_buckets(nullptr),
1416  _M_bucket_count(__ht._M_bucket_count),
1417  _M_element_count(__ht._M_element_count),
1418  _M_rehash_policy(__ht._M_rehash_policy)
1419  {
1420  __alloc_node_gen_t __alloc_node_gen(*this);
1421  _M_assign(__ht, __alloc_node_gen);
1422  }
1423 
1424  template<typename _Key, typename _Value, typename _Alloc,
1425  typename _ExtractKey, typename _Equal,
1426  typename _Hash, typename _RangeHash, typename _Unused,
1427  typename _RehashPolicy, typename _Traits>
1428  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1429  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1430  _Hashtable(_Hashtable&& __ht, __node_alloc_type&& __a,
1431  true_type /* alloc always equal */)
1432  noexcept(_S_nothrow_move())
1433  : __hashtable_base(__ht),
1434  __map_base(__ht),
1435  __rehash_base(__ht),
1436  __hashtable_alloc(std::move(__a)),
1437  __enable_default_ctor(__ht),
1438  _M_buckets(__ht._M_buckets),
1439  _M_bucket_count(__ht._M_bucket_count),
1440  _M_before_begin(__ht._M_before_begin._M_nxt),
1441  _M_element_count(__ht._M_element_count),
1442  _M_rehash_policy(__ht._M_rehash_policy)
1443  {
1444  // Update buckets if __ht is using its single bucket.
1445  if (__ht._M_uses_single_bucket())
1446  {
1447  _M_buckets = &_M_single_bucket;
1448  _M_single_bucket = __ht._M_single_bucket;
1449  }
1450 
1451  // Fix bucket containing the _M_before_begin pointer that can't be moved.
1452  _M_update_bbegin();
1453 
1454  __ht._M_reset();
1455  }
1456 
1457  template<typename _Key, typename _Value, typename _Alloc,
1458  typename _ExtractKey, typename _Equal,
1459  typename _Hash, typename _RangeHash, typename _Unused,
1460  typename _RehashPolicy, typename _Traits>
1461  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1462  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1463  _Hashtable(const _Hashtable& __ht, const allocator_type& __a)
1464  : __hashtable_base(__ht),
1465  __map_base(__ht),
1466  __rehash_base(__ht),
1467  __hashtable_alloc(__node_alloc_type(__a)),
1468  __enable_default_ctor(__ht),
1469  _M_buckets(),
1470  _M_bucket_count(__ht._M_bucket_count),
1471  _M_element_count(__ht._M_element_count),
1472  _M_rehash_policy(__ht._M_rehash_policy)
1473  {
1474  __alloc_node_gen_t __alloc_node_gen(*this);
1475  _M_assign(__ht, __alloc_node_gen);
1476  }
1477 
1478  template<typename _Key, typename _Value, typename _Alloc,
1479  typename _ExtractKey, typename _Equal,
1480  typename _Hash, typename _RangeHash, typename _Unused,
1481  typename _RehashPolicy, typename _Traits>
1482  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1483  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1484  _Hashtable(_Hashtable&& __ht, __node_alloc_type&& __a,
1485  false_type /* alloc always equal */)
1486  : __hashtable_base(__ht),
1487  __map_base(__ht),
1488  __rehash_base(__ht),
1489  __hashtable_alloc(std::move(__a)),
1490  __enable_default_ctor(__ht),
1491  _M_buckets(nullptr),
1492  _M_bucket_count(__ht._M_bucket_count),
1493  _M_element_count(__ht._M_element_count),
1494  _M_rehash_policy(__ht._M_rehash_policy)
1495  {
1496  if (__ht._M_node_allocator() == this->_M_node_allocator())
1497  {
1498  if (__ht._M_uses_single_bucket())
1499  {
1500  _M_buckets = &_M_single_bucket;
1501  _M_single_bucket = __ht._M_single_bucket;
1502  }
1503  else
1504  _M_buckets = __ht._M_buckets;
1505 
1506  // Fix bucket containing the _M_before_begin pointer that can't be
1507  // moved.
1508  _M_update_bbegin(__ht._M_begin());
1509 
1510  __ht._M_reset();
1511  }
1512  else
1513  {
1514  __alloc_node_gen_t __alloc_gen(*this);
1515 
1516  using _Fwd_Ht = typename
1517  conditional<__move_if_noexcept_cond<value_type>::value,
1518  const _Hashtable&, _Hashtable&&>::type;
1519  _M_assign(std::forward<_Fwd_Ht>(__ht), __alloc_gen);
1520  __ht.clear();
1521  }
1522  }
1523 
1524  template<typename _Key, typename _Value, typename _Alloc,
1525  typename _ExtractKey, typename _Equal,
1526  typename _Hash, typename _RangeHash, typename _Unused,
1527  typename _RehashPolicy, typename _Traits>
1528  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1529  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1530  ~_Hashtable() noexcept
1531  {
1532  clear();
1533  _M_deallocate_buckets();
1534  }
1535 
1536  template<typename _Key, typename _Value, typename _Alloc,
1537  typename _ExtractKey, typename _Equal,
1538  typename _Hash, typename _RangeHash, typename _Unused,
1539  typename _RehashPolicy, typename _Traits>
1540  void
1541  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1542  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1543  swap(_Hashtable& __x)
1544  noexcept(__and_<__is_nothrow_swappable<_Hash>,
1545  __is_nothrow_swappable<_Equal>>::value)
1546  {
1547  // The only base class with member variables is hash_code_base.
1548  // We define _Hash_code_base::_M_swap because different
1549  // specializations have different members.
1550  this->_M_swap(__x);
1551 
1552  std::__alloc_on_swap(this->_M_node_allocator(), __x._M_node_allocator());
1553  std::swap(_M_rehash_policy, __x._M_rehash_policy);
1554 
1555  // Deal properly with potentially moved instances.
1556  if (this->_M_uses_single_bucket())
1557  {
1558  if (!__x._M_uses_single_bucket())
1559  {
1560  _M_buckets = __x._M_buckets;
1561  __x._M_buckets = &__x._M_single_bucket;
1562  }
1563  }
1564  else if (__x._M_uses_single_bucket())
1565  {
1566  __x._M_buckets = _M_buckets;
1567  _M_buckets = &_M_single_bucket;
1568  }
1569  else
1570  std::swap(_M_buckets, __x._M_buckets);
1571 
1572  std::swap(_M_bucket_count, __x._M_bucket_count);
1573  std::swap(_M_before_begin._M_nxt, __x._M_before_begin._M_nxt);
1574  std::swap(_M_element_count, __x._M_element_count);
1575  std::swap(_M_single_bucket, __x._M_single_bucket);
1576 
1577  // Fix buckets containing the _M_before_begin pointers that can't be
1578  // swapped.
1579  _M_update_bbegin();
1580  __x._M_update_bbegin();
1581  }
1582 
1583  template<typename _Key, typename _Value, typename _Alloc,
1584  typename _ExtractKey, typename _Equal,
1585  typename _Hash, typename _RangeHash, typename _Unused,
1586  typename _RehashPolicy, typename _Traits>
1587  auto
1588  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1589  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1590  find(const key_type& __k)
1591  -> iterator
1592  {
1593  __hash_code __code = this->_M_hash_code(__k);
1594  std::size_t __bkt = _M_bucket_index(__code);
1595  return iterator(_M_find_node(__bkt, __k, __code));
1596  }
1597 
1598  template<typename _Key, typename _Value, typename _Alloc,
1599  typename _ExtractKey, typename _Equal,
1600  typename _Hash, typename _RangeHash, typename _Unused,
1601  typename _RehashPolicy, typename _Traits>
1602  auto
1603  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1604  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1605  find(const key_type& __k) const
1606  -> const_iterator
1607  {
1608  __hash_code __code = this->_M_hash_code(__k);
1609  std::size_t __bkt = _M_bucket_index(__code);
1610  return const_iterator(_M_find_node(__bkt, __k, __code));
1611  }
1612 
1613 #if __cplusplus > 201703L
1614  template<typename _Key, typename _Value, typename _Alloc,
1615  typename _ExtractKey, typename _Equal,
1616  typename _Hash, typename _RangeHash, typename _Unused,
1617  typename _RehashPolicy, typename _Traits>
1618  template<typename _Kt, typename, typename>
1619  auto
1620  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1621  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1622  _M_find_tr(const _Kt& __k)
1623  -> iterator
1624  {
1625  __hash_code __code = this->_M_hash_code_tr(__k);
1626  std::size_t __bkt = _M_bucket_index(__code);
1627  return iterator(_M_find_node_tr(__bkt, __k, __code));
1628  }
1629 
1630  template<typename _Key, typename _Value, typename _Alloc,
1631  typename _ExtractKey, typename _Equal,
1632  typename _Hash, typename _RangeHash, typename _Unused,
1633  typename _RehashPolicy, typename _Traits>
1634  template<typename _Kt, typename, typename>
1635  auto
1636  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1637  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1638  _M_find_tr(const _Kt& __k) const
1639  -> const_iterator
1640  {
1641  __hash_code __code = this->_M_hash_code_tr(__k);
1642  std::size_t __bkt = _M_bucket_index(__code);
1643  return const_iterator(_M_find_node_tr(__bkt, __k, __code));
1644  }
1645 #endif
1646 
1647  template<typename _Key, typename _Value, typename _Alloc,
1648  typename _ExtractKey, typename _Equal,
1649  typename _Hash, typename _RangeHash, typename _Unused,
1650  typename _RehashPolicy, typename _Traits>
1651  auto
1652  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1653  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1654  count(const key_type& __k) const
1655  -> size_type
1656  {
1657  auto __it = find(__k);
1658  if (!__it._M_cur)
1659  return 0;
1660 
1661  if (__unique_keys::value)
1662  return 1;
1663 
1664  // All equivalent values are next to each other, if we find a
1665  // non-equivalent value after an equivalent one it means that we won't
1666  // find any new equivalent value.
1667  size_type __result = 1;
1668  for (auto __ref = __it++;
1669  __it._M_cur && this->_M_node_equals(*__ref._M_cur, *__it._M_cur);
1670  ++__it)
1671  ++__result;
1672 
1673  return __result;
1674  }
1675 
1676 #if __cplusplus > 201703L
1677  template<typename _Key, typename _Value, typename _Alloc,
1678  typename _ExtractKey, typename _Equal,
1679  typename _Hash, typename _RangeHash, typename _Unused,
1680  typename _RehashPolicy, typename _Traits>
1681  template<typename _Kt, typename, typename>
1682  auto
1683  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1684  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1685  _M_count_tr(const _Kt& __k) const
1686  -> size_type
1687  {
1688  __hash_code __code = this->_M_hash_code_tr(__k);
1689  std::size_t __bkt = _M_bucket_index(__code);
1690  auto __n = _M_find_node_tr(__bkt, __k, __code);
1691  if (!__n)
1692  return 0;
1693 
1694  // All equivalent values are next to each other, if we find a
1695  // non-equivalent value after an equivalent one it means that we won't
1696  // find any new equivalent value.
1697  iterator __it(__n);
1698  size_type __result = 1;
1699  for (++__it;
1700  __it._M_cur && this->_M_equals_tr(__k, __code, *__it._M_cur);
1701  ++__it)
1702  ++__result;
1703 
1704  return __result;
1705  }
1706 #endif
1707 
1708  template<typename _Key, typename _Value, typename _Alloc,
1709  typename _ExtractKey, typename _Equal,
1710  typename _Hash, typename _RangeHash, typename _Unused,
1711  typename _RehashPolicy, typename _Traits>
1712  auto
1713  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1714  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1715  equal_range(const key_type& __k)
1716  -> pair<iterator, iterator>
1717  {
1718  auto __ite = find(__k);
1719  if (!__ite._M_cur)
1720  return { __ite, __ite };
1721 
1722  auto __beg = __ite++;
1723  if (__unique_keys::value)
1724  return { __beg, __ite };
1725 
1726  // All equivalent values are next to each other, if we find a
1727  // non-equivalent value after an equivalent one it means that we won't
1728  // find any new equivalent value.
1729  while (__ite._M_cur && this->_M_node_equals(*__beg._M_cur, *__ite._M_cur))
1730  ++__ite;
1731 
1732  return { __beg, __ite };
1733  }
1734 
1735  template<typename _Key, typename _Value, typename _Alloc,
1736  typename _ExtractKey, typename _Equal,
1737  typename _Hash, typename _RangeHash, typename _Unused,
1738  typename _RehashPolicy, typename _Traits>
1739  auto
1740  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1741  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1742  equal_range(const key_type& __k) const
1743  -> pair<const_iterator, const_iterator>
1744  {
1745  auto __ite = find(__k);
1746  if (!__ite._M_cur)
1747  return { __ite, __ite };
1748 
1749  auto __beg = __ite++;
1750  if (__unique_keys::value)
1751  return { __beg, __ite };
1752 
1753  // All equivalent values are next to each other, if we find a
1754  // non-equivalent value after an equivalent one it means that we won't
1755  // find any new equivalent value.
1756  while (__ite._M_cur && this->_M_node_equals(*__beg._M_cur, *__ite._M_cur))
1757  ++__ite;
1758 
1759  return { __beg, __ite };
1760  }
1761 
1762 #if __cplusplus > 201703L
1763  template<typename _Key, typename _Value, typename _Alloc,
1764  typename _ExtractKey, typename _Equal,
1765  typename _Hash, typename _RangeHash, typename _Unused,
1766  typename _RehashPolicy, typename _Traits>
1767  template<typename _Kt, typename, typename>
1768  auto
1769  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1770  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1771  _M_equal_range_tr(const _Kt& __k)
1772  -> pair<iterator, iterator>
1773  {
1774  __hash_code __code = this->_M_hash_code_tr(__k);
1775  std::size_t __bkt = _M_bucket_index(__code);
1776  auto __n = _M_find_node_tr(__bkt, __k, __code);
1777  iterator __ite(__n);
1778  if (!__n)
1779  return { __ite, __ite };
1780 
1781  // All equivalent values are next to each other, if we find a
1782  // non-equivalent value after an equivalent one it means that we won't
1783  // find any new equivalent value.
1784  auto __beg = __ite++;
1785  while (__ite._M_cur && this->_M_equals_tr(__k, __code, *__ite._M_cur))
1786  ++__ite;
1787 
1788  return { __beg, __ite };
1789  }
1790 
1791  template<typename _Key, typename _Value, typename _Alloc,
1792  typename _ExtractKey, typename _Equal,
1793  typename _Hash, typename _RangeHash, typename _Unused,
1794  typename _RehashPolicy, typename _Traits>
1795  template<typename _Kt, typename, typename>
1796  auto
1797  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1798  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1799  _M_equal_range_tr(const _Kt& __k) const
1800  -> pair<const_iterator, const_iterator>
1801  {
1802  __hash_code __code = this->_M_hash_code_tr(__k);
1803  std::size_t __bkt = _M_bucket_index(__code);
1804  auto __n = _M_find_node_tr(__bkt, __k, __code);
1805  const_iterator __ite(__n);
1806  if (!__n)
1807  return { __ite, __ite };
1808 
1809  // All equivalent values are next to each other, if we find a
1810  // non-equivalent value after an equivalent one it means that we won't
1811  // find any new equivalent value.
1812  auto __beg = __ite++;
1813  while (__ite._M_cur && this->_M_equals_tr(__k, __code, *__ite._M_cur))
1814  ++__ite;
1815 
1816  return { __beg, __ite };
1817  }
1818 #endif
1819 
1820  // Find the node before the one whose key compares equal to k in the bucket
1821  // bkt. Return nullptr if no node is found.
1822  template<typename _Key, typename _Value, typename _Alloc,
1823  typename _ExtractKey, typename _Equal,
1824  typename _Hash, typename _RangeHash, typename _Unused,
1825  typename _RehashPolicy, typename _Traits>
1826  auto
1827  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1828  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1829  _M_find_before_node(size_type __bkt, const key_type& __k,
1830  __hash_code __code) const
1831  -> __node_base_ptr
1832  {
1833  __node_base_ptr __prev_p = _M_buckets[__bkt];
1834  if (!__prev_p)
1835  return nullptr;
1836 
1837  for (__node_ptr __p = static_cast<__node_ptr>(__prev_p->_M_nxt);;
1838  __p = __p->_M_next())
1839  {
1840  if (this->_M_equals(__k, __code, *__p))
1841  return __prev_p;
1842 
1843  if (!__p->_M_nxt || _M_bucket_index(*__p->_M_next()) != __bkt)
1844  break;
1845  __prev_p = __p;
1846  }
1847 
1848  return nullptr;
1849  }
1850 
1851  template<typename _Key, typename _Value, typename _Alloc,
1852  typename _ExtractKey, typename _Equal,
1853  typename _Hash, typename _RangeHash, typename _Unused,
1854  typename _RehashPolicy, typename _Traits>
1855  template<typename _Kt>
1856  auto
1857  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1858  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1859  _M_find_before_node_tr(size_type __bkt, const _Kt& __k,
1860  __hash_code __code) const
1861  -> __node_base_ptr
1862  {
1863  __node_base_ptr __prev_p = _M_buckets[__bkt];
1864  if (!__prev_p)
1865  return nullptr;
1866 
1867  for (__node_ptr __p = static_cast<__node_ptr>(__prev_p->_M_nxt);;
1868  __p = __p->_M_next())
1869  {
1870  if (this->_M_equals_tr(__k, __code, *__p))
1871  return __prev_p;
1872 
1873  if (!__p->_M_nxt || _M_bucket_index(*__p->_M_next()) != __bkt)
1874  break;
1875  __prev_p = __p;
1876  }
1877 
1878  return nullptr;
1879  }
1880 
1881  template<typename _Key, typename _Value, typename _Alloc,
1882  typename _ExtractKey, typename _Equal,
1883  typename _Hash, typename _RangeHash, typename _Unused,
1884  typename _RehashPolicy, typename _Traits>
1885  void
1886  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1887  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1888  _M_insert_bucket_begin(size_type __bkt, __node_ptr __node)
1889  {
1890  if (_M_buckets[__bkt])
1891  {
1892  // Bucket is not empty, we just need to insert the new node
1893  // after the bucket before begin.
1894  __node->_M_nxt = _M_buckets[__bkt]->_M_nxt;
1895  _M_buckets[__bkt]->_M_nxt = __node;
1896  }
1897  else
1898  {
1899  // The bucket is empty, the new node is inserted at the
1900  // beginning of the singly-linked list and the bucket will
1901  // contain _M_before_begin pointer.
1902  __node->_M_nxt = _M_before_begin._M_nxt;
1903  _M_before_begin._M_nxt = __node;
1904 
1905  if (__node->_M_nxt)
1906  // We must update former begin bucket that is pointing to
1907  // _M_before_begin.
1908  _M_buckets[_M_bucket_index(*__node->_M_next())] = __node;
1909 
1910  _M_buckets[__bkt] = &_M_before_begin;
1911  }
1912  }
1913 
1914  template<typename _Key, typename _Value, typename _Alloc,
1915  typename _ExtractKey, typename _Equal,
1916  typename _Hash, typename _RangeHash, typename _Unused,
1917  typename _RehashPolicy, typename _Traits>
1918  void
1919  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1920  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1921  _M_remove_bucket_begin(size_type __bkt, __node_ptr __next,
1922  size_type __next_bkt)
1923  {
1924  if (!__next || __next_bkt != __bkt)
1925  {
1926  // Bucket is now empty
1927  // First update next bucket if any
1928  if (__next)
1929  _M_buckets[__next_bkt] = _M_buckets[__bkt];
1930 
1931  // Second update before begin node if necessary
1932  if (&_M_before_begin == _M_buckets[__bkt])
1933  _M_before_begin._M_nxt = __next;
1934  _M_buckets[__bkt] = nullptr;
1935  }
1936  }
1937 
1938  template<typename _Key, typename _Value, typename _Alloc,
1939  typename _ExtractKey, typename _Equal,
1940  typename _Hash, typename _RangeHash, typename _Unused,
1941  typename _RehashPolicy, typename _Traits>
1942  auto
1943  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1944  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1945  _M_get_previous_node(size_type __bkt, __node_ptr __n)
1946  -> __node_base_ptr
1947  {
1948  __node_base_ptr __prev_n = _M_buckets[__bkt];
1949  while (__prev_n->_M_nxt != __n)
1950  __prev_n = __prev_n->_M_nxt;
1951  return __prev_n;
1952  }
1953 
1954  template<typename _Key, typename _Value, typename _Alloc,
1955  typename _ExtractKey, typename _Equal,
1956  typename _Hash, typename _RangeHash, typename _Unused,
1957  typename _RehashPolicy, typename _Traits>
1958  template<typename... _Args>
1959  auto
1960  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1961  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1962  _M_emplace(true_type /* __uks */, _Args&&... __args)
1963  -> pair<iterator, bool>
1964  {
1965  // First build the node to get access to the hash code
1966  _Scoped_node __node { this, std::forward<_Args>(__args)... };
1967  const key_type& __k = _ExtractKey{}(__node._M_node->_M_v());
1968  __hash_code __code = this->_M_hash_code(__k);
1969  size_type __bkt = _M_bucket_index(__code);
1970  if (__node_ptr __p = _M_find_node(__bkt, __k, __code))
1971  // There is already an equivalent node, no insertion
1972  return std::make_pair(iterator(__p), false);
1973 
1974  // Insert the node
1975  auto __pos = _M_insert_unique_node(__bkt, __code, __node._M_node);
1976  __node._M_node = nullptr;
1977  return { __pos, true };
1978  }
1979 
1980  template<typename _Key, typename _Value, typename _Alloc,
1981  typename _ExtractKey, typename _Equal,
1982  typename _Hash, typename _RangeHash, typename _Unused,
1983  typename _RehashPolicy, typename _Traits>
1984  template<typename... _Args>
1985  auto
1986  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1987  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
1988  _M_emplace(const_iterator __hint, false_type /* __uks */,
1989  _Args&&... __args)
1990  -> iterator
1991  {
1992  // First build the node to get its hash code.
1993  _Scoped_node __node { this, std::forward<_Args>(__args)... };
1994  const key_type& __k = _ExtractKey{}(__node._M_node->_M_v());
1995 
1996  __hash_code __code = this->_M_hash_code(__k);
1997  auto __pos
1998  = _M_insert_multi_node(__hint._M_cur, __code, __node._M_node);
1999  __node._M_node = nullptr;
2000  return __pos;
2001  }
2002 
2003  template<typename _Key, typename _Value, typename _Alloc,
2004  typename _ExtractKey, typename _Equal,
2005  typename _Hash, typename _RangeHash, typename _Unused,
2006  typename _RehashPolicy, typename _Traits>
2007  auto
2008  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2009  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2010  _M_insert_unique_node(size_type __bkt, __hash_code __code,
2011  __node_ptr __node, size_type __n_elt)
2012  -> iterator
2013  {
2014  const __rehash_state& __saved_state = _M_rehash_policy._M_state();
2015  std::pair<bool, std::size_t> __do_rehash
2016  = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count,
2017  __n_elt);
2018 
2019  if (__do_rehash.first)
2020  {
2021  _M_rehash(__do_rehash.second, __saved_state);
2022  __bkt = _M_bucket_index(__code);
2023  }
2024 
2025  this->_M_store_code(*__node, __code);
2026 
2027  // Always insert at the beginning of the bucket.
2028  _M_insert_bucket_begin(__bkt, __node);
2029  ++_M_element_count;
2030  return iterator(__node);
2031  }
2032 
2033  template<typename _Key, typename _Value, typename _Alloc,
2034  typename _ExtractKey, typename _Equal,
2035  typename _Hash, typename _RangeHash, typename _Unused,
2036  typename _RehashPolicy, typename _Traits>
2037  auto
2038  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2039  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2040  _M_insert_multi_node(__node_ptr __hint,
2041  __hash_code __code, __node_ptr __node)
2042  -> iterator
2043  {
2044  const __rehash_state& __saved_state = _M_rehash_policy._M_state();
2045  std::pair<bool, std::size_t> __do_rehash
2046  = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count, 1);
2047 
2048  if (__do_rehash.first)
2049  _M_rehash(__do_rehash.second, __saved_state);
2050 
2051  this->_M_store_code(*__node, __code);
2052  const key_type& __k = _ExtractKey{}(__node->_M_v());
2053  size_type __bkt = _M_bucket_index(__code);
2054 
2055  // Find the node before an equivalent one or use hint if it exists and
2056  // if it is equivalent.
2057  __node_base_ptr __prev
2058  = __builtin_expect(__hint != nullptr, false)
2059  && this->_M_equals(__k, __code, *__hint)
2060  ? __hint
2061  : _M_find_before_node(__bkt, __k, __code);
2062 
2063  if (__prev)
2064  {
2065  // Insert after the node before the equivalent one.
2066  __node->_M_nxt = __prev->_M_nxt;
2067  __prev->_M_nxt = __node;
2068  if (__builtin_expect(__prev == __hint, false))
2069  // hint might be the last bucket node, in this case we need to
2070  // update next bucket.
2071  if (__node->_M_nxt
2072  && !this->_M_equals(__k, __code, *__node->_M_next()))
2073  {
2074  size_type __next_bkt = _M_bucket_index(*__node->_M_next());
2075  if (__next_bkt != __bkt)
2076  _M_buckets[__next_bkt] = __node;
2077  }
2078  }
2079  else
2080  // The inserted node has no equivalent in the hashtable. We must
2081  // insert the new node at the beginning of the bucket to preserve
2082  // equivalent elements' relative positions.
2083  _M_insert_bucket_begin(__bkt, __node);
2084  ++_M_element_count;
2085  return iterator(__node);
2086  }
2087 
2088  // Insert v if no element with its key is already present.
2089  template<typename _Key, typename _Value, typename _Alloc,
2090  typename _ExtractKey, typename _Equal,
2091  typename _Hash, typename _RangeHash, typename _Unused,
2092  typename _RehashPolicy, typename _Traits>
2093  template<typename _Arg, typename _NodeGenerator>
2094  auto
2095  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2096  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2097  _M_insert(_Arg&& __v, const _NodeGenerator& __node_gen,
2098  true_type /* __uks */)
2099  -> pair<iterator, bool>
2100  {
2101  const key_type& __k = _ExtractKey{}(__v);
2102  __hash_code __code = this->_M_hash_code(__k);
2103  size_type __bkt = _M_bucket_index(__code);
2104 
2105  if (__node_ptr __node = _M_find_node(__bkt, __k, __code))
2106  return { iterator(__node), false };
2107 
2108  _Scoped_node __node{ __node_gen(std::forward<_Arg>(__v)), this };
2109  auto __pos
2110  = _M_insert_unique_node(__bkt, __code, __node._M_node);
2111  __node._M_node = nullptr;
2112  return { __pos, true };
2113  }
2114 
2115  // Insert v unconditionally.
2116  template<typename _Key, typename _Value, typename _Alloc,
2117  typename _ExtractKey, typename _Equal,
2118  typename _Hash, typename _RangeHash, typename _Unused,
2119  typename _RehashPolicy, typename _Traits>
2120  template<typename _Arg, typename _NodeGenerator>
2121  auto
2122  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2123  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2124  _M_insert(const_iterator __hint, _Arg&& __v,
2125  const _NodeGenerator& __node_gen,
2126  false_type /* __uks */)
2127  -> iterator
2128  {
2129  // First compute the hash code so that we don't do anything if it
2130  // throws.
2131  __hash_code __code = this->_M_hash_code(_ExtractKey{}(__v));
2132 
2133  // Second allocate new node so that we don't rehash if it throws.
2134  _Scoped_node __node{ __node_gen(std::forward<_Arg>(__v)), this };
2135  auto __pos
2136  = _M_insert_multi_node(__hint._M_cur, __code, __node._M_node);
2137  __node._M_node = nullptr;
2138  return __pos;
2139  }
2140 
2141  template<typename _Key, typename _Value, typename _Alloc,
2142  typename _ExtractKey, typename _Equal,
2143  typename _Hash, typename _RangeHash, typename _Unused,
2144  typename _RehashPolicy, typename _Traits>
2145  auto
2146  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2147  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2148  erase(const_iterator __it)
2149  -> iterator
2150  {
2151  __node_ptr __n = __it._M_cur;
2152  std::size_t __bkt = _M_bucket_index(*__n);
2153 
2154  // Look for previous node to unlink it from the erased one, this
2155  // is why we need buckets to contain the before begin to make
2156  // this search fast.
2157  __node_base_ptr __prev_n = _M_get_previous_node(__bkt, __n);
2158  return _M_erase(__bkt, __prev_n, __n);
2159  }
2160 
2161  template<typename _Key, typename _Value, typename _Alloc,
2162  typename _ExtractKey, typename _Equal,
2163  typename _Hash, typename _RangeHash, typename _Unused,
2164  typename _RehashPolicy, typename _Traits>
2165  auto
2166  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2167  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2168  _M_erase(size_type __bkt, __node_base_ptr __prev_n, __node_ptr __n)
2169  -> iterator
2170  {
2171  if (__prev_n == _M_buckets[__bkt])
2172  _M_remove_bucket_begin(__bkt, __n->_M_next(),
2173  __n->_M_nxt ? _M_bucket_index(*__n->_M_next()) : 0);
2174  else if (__n->_M_nxt)
2175  {
2176  size_type __next_bkt = _M_bucket_index(*__n->_M_next());
2177  if (__next_bkt != __bkt)
2178  _M_buckets[__next_bkt] = __prev_n;
2179  }
2180 
2181  __prev_n->_M_nxt = __n->_M_nxt;
2182  iterator __result(__n->_M_next());
2183  this->_M_deallocate_node(__n);
2184  --_M_element_count;
2185 
2186  return __result;
2187  }
2188 
2189  template<typename _Key, typename _Value, typename _Alloc,
2190  typename _ExtractKey, typename _Equal,
2191  typename _Hash, typename _RangeHash, typename _Unused,
2192  typename _RehashPolicy, typename _Traits>
2193  auto
2194  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2195  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2196  _M_erase(true_type /* __uks */, const key_type& __k)
2197  -> size_type
2198  {
2199  __hash_code __code = this->_M_hash_code(__k);
2200  std::size_t __bkt = _M_bucket_index(__code);
2201 
2202  // Look for the node before the first matching node.
2203  __node_base_ptr __prev_n = _M_find_before_node(__bkt, __k, __code);
2204  if (!__prev_n)
2205  return 0;
2206 
2207  // We found a matching node, erase it.
2208  __node_ptr __n = static_cast<__node_ptr>(__prev_n->_M_nxt);
2209  _M_erase(__bkt, __prev_n, __n);
2210  return 1;
2211  }
2212 
2213  template<typename _Key, typename _Value, typename _Alloc,
2214  typename _ExtractKey, typename _Equal,
2215  typename _Hash, typename _RangeHash, typename _Unused,
2216  typename _RehashPolicy, typename _Traits>
2217  auto
2218  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2219  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2220  _M_erase(false_type /* __uks */, const key_type& __k)
2221  -> size_type
2222  {
2223  __hash_code __code = this->_M_hash_code(__k);
2224  std::size_t __bkt = _M_bucket_index(__code);
2225 
2226  // Look for the node before the first matching node.
2227  __node_base_ptr __prev_n = _M_find_before_node(__bkt, __k, __code);
2228  if (!__prev_n)
2229  return 0;
2230 
2231  // _GLIBCXX_RESOLVE_LIB_DEFECTS
2232  // 526. Is it undefined if a function in the standard changes
2233  // in parameters?
2234  // We use one loop to find all matching nodes and another to deallocate
2235  // them so that the key stays valid during the first loop. It might be
2236  // invalidated indirectly when destroying nodes.
2237  __node_ptr __n = static_cast<__node_ptr>(__prev_n->_M_nxt);
2238  __node_ptr __n_last = __n->_M_next();
2239  while (__n_last && this->_M_node_equals(*__n, *__n_last))
2240  __n_last = __n_last->_M_next();
2241 
2242  std::size_t __n_last_bkt = __n_last ? _M_bucket_index(*__n_last) : __bkt;
2243 
2244  // Deallocate nodes.
2245  size_type __result = 0;
2246  do
2247  {
2248  __node_ptr __p = __n->_M_next();
2249  this->_M_deallocate_node(__n);
2250  __n = __p;
2251  ++__result;
2252  }
2253  while (__n != __n_last);
2254 
2255  _M_element_count -= __result;
2256  if (__prev_n == _M_buckets[__bkt])
2257  _M_remove_bucket_begin(__bkt, __n_last, __n_last_bkt);
2258  else if (__n_last_bkt != __bkt)
2259  _M_buckets[__n_last_bkt] = __prev_n;
2260  __prev_n->_M_nxt = __n_last;
2261  return __result;
2262  }
2263 
2264  template<typename _Key, typename _Value, typename _Alloc,
2265  typename _ExtractKey, typename _Equal,
2266  typename _Hash, typename _RangeHash, typename _Unused,
2267  typename _RehashPolicy, typename _Traits>
2268  auto
2269  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2270  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2271  erase(const_iterator __first, const_iterator __last)
2272  -> iterator
2273  {
2274  __node_ptr __n = __first._M_cur;
2275  __node_ptr __last_n = __last._M_cur;
2276  if (__n == __last_n)
2277  return iterator(__n);
2278 
2279  std::size_t __bkt = _M_bucket_index(*__n);
2280 
2281  __node_base_ptr __prev_n = _M_get_previous_node(__bkt, __n);
2282  bool __is_bucket_begin = __n == _M_bucket_begin(__bkt);
2283  std::size_t __n_bkt = __bkt;
2284  for (;;)
2285  {
2286  do
2287  {
2288  __node_ptr __tmp = __n;
2289  __n = __n->_M_next();
2290  this->_M_deallocate_node(__tmp);
2291  --_M_element_count;
2292  if (!__n)
2293  break;
2294  __n_bkt = _M_bucket_index(*__n);
2295  }
2296  while (__n != __last_n && __n_bkt == __bkt);
2297  if (__is_bucket_begin)
2298  _M_remove_bucket_begin(__bkt, __n, __n_bkt);
2299  if (__n == __last_n)
2300  break;
2301  __is_bucket_begin = true;
2302  __bkt = __n_bkt;
2303  }
2304 
2305  if (__n && (__n_bkt != __bkt || __is_bucket_begin))
2306  _M_buckets[__n_bkt] = __prev_n;
2307  __prev_n->_M_nxt = __n;
2308  return iterator(__n);
2309  }
2310 
2311  template<typename _Key, typename _Value, typename _Alloc,
2312  typename _ExtractKey, typename _Equal,
2313  typename _Hash, typename _RangeHash, typename _Unused,
2314  typename _RehashPolicy, typename _Traits>
2315  void
2316  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2317  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2318  clear() noexcept
2319  {
2320  this->_M_deallocate_nodes(_M_begin());
2321  __builtin_memset(_M_buckets, 0,
2322  _M_bucket_count * sizeof(__node_base_ptr));
2323  _M_element_count = 0;
2324  _M_before_begin._M_nxt = nullptr;
2325  }
2326 
2327  template<typename _Key, typename _Value, typename _Alloc,
2328  typename _ExtractKey, typename _Equal,
2329  typename _Hash, typename _RangeHash, typename _Unused,
2330  typename _RehashPolicy, typename _Traits>
2331  void
2332  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2333  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2334  rehash(size_type __bkt_count)
2335  {
2336  const __rehash_state& __saved_state = _M_rehash_policy._M_state();
2337  __bkt_count
2338  = std::max(_M_rehash_policy._M_bkt_for_elements(_M_element_count + 1),
2339  __bkt_count);
2340  __bkt_count = _M_rehash_policy._M_next_bkt(__bkt_count);
2341 
2342  if (__bkt_count != _M_bucket_count)
2343  _M_rehash(__bkt_count, __saved_state);
2344  else
2345  // No rehash, restore previous state to keep it consistent with
2346  // container state.
2347  _M_rehash_policy._M_reset(__saved_state);
2348  }
2349 
2350  template<typename _Key, typename _Value, typename _Alloc,
2351  typename _ExtractKey, typename _Equal,
2352  typename _Hash, typename _RangeHash, typename _Unused,
2353  typename _RehashPolicy, typename _Traits>
2354  void
2355  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2356  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2357  _M_rehash(size_type __bkt_count, const __rehash_state& __state)
2358  {
2359  __try
2360  {
2361  _M_rehash_aux(__bkt_count, __unique_keys{});
2362  }
2363  __catch(...)
2364  {
2365  // A failure here means that buckets allocation failed. We only
2366  // have to restore hash policy previous state.
2367  _M_rehash_policy._M_reset(__state);
2368  __throw_exception_again;
2369  }
2370  }
2371 
2372  // Rehash when there is no equivalent elements.
2373  template<typename _Key, typename _Value, typename _Alloc,
2374  typename _ExtractKey, typename _Equal,
2375  typename _Hash, typename _RangeHash, typename _Unused,
2376  typename _RehashPolicy, typename _Traits>
2377  void
2378  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2379  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2380  _M_rehash_aux(size_type __bkt_count, true_type /* __uks */)
2381  {
2382  __buckets_ptr __new_buckets = _M_allocate_buckets(__bkt_count);
2383  __node_ptr __p = _M_begin();
2384  _M_before_begin._M_nxt = nullptr;
2385  std::size_t __bbegin_bkt = 0;
2386  while (__p)
2387  {
2388  __node_ptr __next = __p->_M_next();
2389  std::size_t __bkt
2390  = __hash_code_base::_M_bucket_index(*__p, __bkt_count);
2391  if (!__new_buckets[__bkt])
2392  {
2393  __p->_M_nxt = _M_before_begin._M_nxt;
2394  _M_before_begin._M_nxt = __p;
2395  __new_buckets[__bkt] = &_M_before_begin;
2396  if (__p->_M_nxt)
2397  __new_buckets[__bbegin_bkt] = __p;
2398  __bbegin_bkt = __bkt;
2399  }
2400  else
2401  {
2402  __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2403  __new_buckets[__bkt]->_M_nxt = __p;
2404  }
2405 
2406  __p = __next;
2407  }
2408 
2409  _M_deallocate_buckets();
2410  _M_bucket_count = __bkt_count;
2411  _M_buckets = __new_buckets;
2412  }
2413 
2414  // Rehash when there can be equivalent elements, preserve their relative
2415  // order.
2416  template<typename _Key, typename _Value, typename _Alloc,
2417  typename _ExtractKey, typename _Equal,
2418  typename _Hash, typename _RangeHash, typename _Unused,
2419  typename _RehashPolicy, typename _Traits>
2420  void
2421  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2422  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
2423  _M_rehash_aux(size_type __bkt_count, false_type /* __uks */)
2424  {
2425  __buckets_ptr __new_buckets = _M_allocate_buckets(__bkt_count);
2426  __node_ptr __p = _M_begin();
2427  _M_before_begin._M_nxt = nullptr;
2428  std::size_t __bbegin_bkt = 0;
2429  std::size_t __prev_bkt = 0;
2430  __node_ptr __prev_p = nullptr;
2431  bool __check_bucket = false;
2432 
2433  while (__p)
2434  {
2435  __node_ptr __next = __p->_M_next();
2436  std::size_t __bkt
2437  = __hash_code_base::_M_bucket_index(*__p, __bkt_count);
2438 
2439  if (__prev_p && __prev_bkt == __bkt)
2440  {
2441  // Previous insert was already in this bucket, we insert after
2442  // the previously inserted one to preserve equivalent elements
2443  // relative order.
2444  __p->_M_nxt = __prev_p->_M_nxt;
2445  __prev_p->_M_nxt = __p;
2446 
2447  // Inserting after a node in a bucket require to check that we
2448  // haven't change the bucket last node, in this case next
2449  // bucket containing its before begin node must be updated. We
2450  // schedule a check as soon as we move out of the sequence of
2451  // equivalent nodes to limit the number of checks.
2452  __check_bucket = true;
2453  }
2454  else
2455  {
2456  if (__check_bucket)
2457  {
2458  // Check if we shall update the next bucket because of
2459  // insertions into __prev_bkt bucket.
2460  if (__prev_p->_M_nxt)
2461  {
2462  std::size_t __next_bkt
2463  = __hash_code_base::_M_bucket_index(
2464  *__prev_p->_M_next(), __bkt_count);
2465  if (__next_bkt != __prev_bkt)
2466  __new_buckets[__next_bkt] = __prev_p;
2467  }
2468  __check_bucket = false;
2469  }
2470 
2471  if (!__new_buckets[__bkt])
2472  {
2473  __p->_M_nxt = _M_before_begin._M_nxt;
2474  _M_before_begin._M_nxt = __p;
2475  __new_buckets[__bkt] = &_M_before_begin;
2476  if (__p->_M_nxt)
2477  __new_buckets[__bbegin_bkt] = __p;
2478  __bbegin_bkt = __bkt;
2479  }
2480  else
2481  {
2482  __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2483  __new_buckets[__bkt]->_M_nxt = __p;
2484  }
2485  }
2486  __prev_p = __p;
2487  __prev_bkt = __bkt;
2488  __p = __next;
2489  }
2490 
2491  if (__check_bucket && __prev_p->_M_nxt)
2492  {
2493  std::size_t __next_bkt
2494  = __hash_code_base::_M_bucket_index(*__prev_p->_M_next(),
2495  __bkt_count);
2496  if (__next_bkt != __prev_bkt)
2497  __new_buckets[__next_bkt] = __prev_p;
2498  }
2499 
2500  _M_deallocate_buckets();
2501  _M_bucket_count = __bkt_count;
2502  _M_buckets = __new_buckets;
2503  }
2504 
2505 #if __cplusplus > 201402L
2506  template<typename, typename, typename> class _Hash_merge_helper { };
2507 #endif // C++17
2508 
2509 #if __cpp_deduction_guides >= 201606
2510  // Used to constrain deduction guides
2511  template<typename _Hash>
2512  using _RequireNotAllocatorOrIntegral
2513  = __enable_if_t<!__or_<is_integral<_Hash>, __is_allocator<_Hash>>::value>;
2514 #endif
2515 
2516 /// @endcond
2517 _GLIBCXX_END_NAMESPACE_VERSION
2518 } // namespace std
2519 
2520 #endif // _HASHTABLE_H
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
Definition: type_traits:86
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition: move.h:77
Struct holding two objects of arbitrary type.
Definition: stl_pair.h:211
_T2 second
The second member.
Definition: stl_pair.h:218
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition: move.h:49
_Tp * end(valarray< _Tp > &__va) noexcept
Return an iterator pointing to one past the last element of the valarray.
Definition: valarray:1237
constexpr auto empty(const _Container &__cont) noexcept(noexcept(__cont.empty())) -> decltype(__cont.empty())
Return whether a container is empty.
Definition: range_access.h:263
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
constexpr auto size(const _Container &__cont) noexcept(noexcept(__cont.size())) -> decltype(__cont.size())
Return the size of a container.
Definition: range_access.h:245
_Tp * begin(valarray< _Tp > &__va) noexcept
Return an iterator pointing to the first element of the valarray.
Definition: valarray:1215
constexpr auto cbegin(const _Container &__cont) noexcept(noexcept(std::begin(__cont))) -> decltype(std::begin(__cont))
Return an iterator pointing to the first element of the const container.
Definition: range_access.h:119
constexpr const _Tp & max(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:254
_T1 first
The first member.
Definition: stl_pair.h:217
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition: type_traits:83
constexpr auto cend(const _Container &__cont) noexcept(noexcept(std::end(__cont))) -> decltype(std::end(__cont))
Return an iterator pointing to one past the last element of the const container.
Definition: range_access.h:130
ISO C++ entities toplevel namespace is std.