libstdc++
bits/hashtable.h
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1 // hashtable.h header -*- C++ -*-
2 
3 // Copyright (C) 2007-2019 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
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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
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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>
36 #if __cplusplus > 201402L
37 # include <bits/node_handle.h>
38 #endif
39 
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>
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>,
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__
193  "unordered container must have the same value_type as its allocator");
194 #endif
195 
196  using __traits_type = _Traits;
197  using __hash_cached = typename __traits_type::__hash_cached;
199  using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>;
200 
202 
203  using __value_alloc_traits =
204  typename __hashtable_alloc::__value_alloc_traits;
205  using __node_alloc_traits =
207  using __node_base = typename __hashtable_alloc::__node_base;
208  using __bucket_type = typename __hashtable_alloc::__bucket_type;
209 
210  public:
211  typedef _Key key_type;
212  typedef _Value value_type;
213  typedef _Alloc allocator_type;
214  typedef _Equal key_equal;
215 
216  // mapped_type, if present, comes from _Map_base.
217  // hasher, if present, comes from _Hash_code_base/_Hashtable_base.
218  typedef typename __value_alloc_traits::pointer pointer;
219  typedef typename __value_alloc_traits::const_pointer const_pointer;
220  typedef value_type& reference;
221  typedef const value_type& const_reference;
222 
223  private:
224  using __rehash_type = _RehashPolicy;
225  using __rehash_state = typename __rehash_type::_State;
226 
227  using __constant_iterators = typename __traits_type::__constant_iterators;
228  using __unique_keys = typename __traits_type::__unique_keys;
229 
230  using __key_extract = typename std::conditional<
231  __constant_iterators::value,
232  __detail::_Identity,
233  __detail::_Select1st>::type;
234 
235  using __hashtable_base = __detail::
236  _Hashtable_base<_Key, _Value, _ExtractKey,
237  _Equal, _H1, _H2, _Hash, _Traits>;
238 
239  using __hash_code_base = typename __hashtable_base::__hash_code_base;
240  using __hash_code = typename __hashtable_base::__hash_code;
241  using __ireturn_type = typename __hashtable_base::__ireturn_type;
242 
243  using __map_base = __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey,
244  _Equal, _H1, _H2, _Hash,
245  _RehashPolicy, _Traits>;
246 
247  using __rehash_base = __detail::_Rehash_base<_Key, _Value, _Alloc,
248  _ExtractKey, _Equal,
249  _H1, _H2, _Hash,
250  _RehashPolicy, _Traits>;
251 
252  using __eq_base = __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey,
253  _Equal, _H1, _H2, _Hash,
254  _RehashPolicy, _Traits>;
255 
256  using __reuse_or_alloc_node_type =
257  __detail::_ReuseOrAllocNode<__node_alloc_type>;
258 
259  // Metaprogramming for picking apart hash caching.
260  template<typename _Cond>
261  using __if_hash_cached = __or_<__not_<__hash_cached>, _Cond>;
262 
263  template<typename _Cond>
264  using __if_hash_not_cached = __or_<__hash_cached, _Cond>;
265 
266  // Compile-time diagnostics.
267 
268  // _Hash_code_base has everything protected, so use this derived type to
269  // access it.
270  struct __hash_code_base_access : __hash_code_base
271  { using __hash_code_base::_M_bucket_index; };
272 
273  // Getting a bucket index from a node shall not throw because it is used
274  // in methods (erase, swap...) that shall not throw.
275  static_assert(noexcept(declval<const __hash_code_base_access&>()
276  ._M_bucket_index((const __node_type*)nullptr,
277  (std::size_t)0)),
278  "Cache the hash code or qualify your functors involved"
279  " in hash code and bucket index computation with noexcept");
280 
281  // Following two static assertions are necessary to guarantee
282  // that local_iterator will be default constructible.
283 
284  // When hash codes are cached local iterator inherits from H2 functor
285  // which must then be default constructible.
286  static_assert(__if_hash_cached<is_default_constructible<_H2>>::value,
287  "Functor used to map hash code to bucket index"
288  " must be default constructible");
289 
290  template<typename _Keya, typename _Valuea, typename _Alloca,
291  typename _ExtractKeya, typename _Equala,
292  typename _H1a, typename _H2a, typename _Hasha,
293  typename _RehashPolicya, typename _Traitsa,
294  bool _Unique_keysa>
295  friend struct __detail::_Map_base;
296 
297  template<typename _Keya, typename _Valuea, typename _Alloca,
298  typename _ExtractKeya, typename _Equala,
299  typename _H1a, typename _H2a, typename _Hasha,
300  typename _RehashPolicya, typename _Traitsa>
301  friend struct __detail::_Insert_base;
302 
303  template<typename _Keya, typename _Valuea, typename _Alloca,
304  typename _ExtractKeya, typename _Equala,
305  typename _H1a, typename _H2a, typename _Hasha,
306  typename _RehashPolicya, typename _Traitsa,
307  bool _Constant_iteratorsa>
308  friend struct __detail::_Insert;
309 
310  public:
311  using size_type = typename __hashtable_base::size_type;
312  using difference_type = typename __hashtable_base::difference_type;
313 
314  using iterator = typename __hashtable_base::iterator;
315  using const_iterator = typename __hashtable_base::const_iterator;
316 
317  using local_iterator = typename __hashtable_base::local_iterator;
318  using const_local_iterator = typename __hashtable_base::
319  const_local_iterator;
320 
321 #if __cplusplus > 201402L
322  using node_type = _Node_handle<_Key, _Value, __node_alloc_type>;
323  using insert_return_type = _Node_insert_return<iterator, node_type>;
324 #endif
325 
326  private:
327  __bucket_type* _M_buckets = &_M_single_bucket;
328  size_type _M_bucket_count = 1;
329  __node_base _M_before_begin;
330  size_type _M_element_count = 0;
331  _RehashPolicy _M_rehash_policy;
332 
333  // A single bucket used when only need for 1 bucket. Especially
334  // interesting in move semantic to leave hashtable with only 1 buckets
335  // which is not allocated so that we can have those operations noexcept
336  // qualified.
337  // Note that we can't leave hashtable with 0 bucket without adding
338  // numerous checks in the code to avoid 0 modulus.
339  __bucket_type _M_single_bucket = nullptr;
340 
341  bool
342  _M_uses_single_bucket(__bucket_type* __bkts) const
343  { return __builtin_expect(__bkts == &_M_single_bucket, false); }
344 
345  bool
346  _M_uses_single_bucket() const
347  { return _M_uses_single_bucket(_M_buckets); }
348 
350  _M_base_alloc() { return *this; }
351 
352  __bucket_type*
353  _M_allocate_buckets(size_type __n)
354  {
355  if (__builtin_expect(__n == 1, false))
356  {
357  _M_single_bucket = nullptr;
358  return &_M_single_bucket;
359  }
360 
361  return __hashtable_alloc::_M_allocate_buckets(__n);
362  }
363 
364  void
365  _M_deallocate_buckets(__bucket_type* __bkts, size_type __n)
366  {
367  if (_M_uses_single_bucket(__bkts))
368  return;
369 
370  __hashtable_alloc::_M_deallocate_buckets(__bkts, __n);
371  }
372 
373  void
374  _M_deallocate_buckets()
375  { _M_deallocate_buckets(_M_buckets, _M_bucket_count); }
376 
377  // Gets bucket begin, deals with the fact that non-empty buckets contain
378  // their before begin node.
379  __node_type*
380  _M_bucket_begin(size_type __bkt) const;
381 
382  __node_type*
383  _M_begin() const
384  { return static_cast<__node_type*>(_M_before_begin._M_nxt); }
385 
386  // Assign *this using another _Hashtable instance. Either elements
387  // are copy or move depends on the _NodeGenerator.
388  template<typename _Ht, typename _NodeGenerator>
389  void
390  _M_assign_elements(_Ht&&, const _NodeGenerator&);
391 
392  template<typename _NodeGenerator>
393  void
394  _M_assign(const _Hashtable&, const _NodeGenerator&);
395 
396  void
397  _M_move_assign(_Hashtable&&, std::true_type);
398 
399  void
400  _M_move_assign(_Hashtable&&, std::false_type);
401 
402  void
403  _M_reset() noexcept;
404 
405  _Hashtable(const _H1& __h1, const _H2& __h2, const _Hash& __h,
406  const _Equal& __eq, const _ExtractKey& __exk,
407  const allocator_type& __a)
408  : __hashtable_base(__exk, __h1, __h2, __h, __eq),
409  __hashtable_alloc(__node_alloc_type(__a))
410  { }
411 
412  public:
413  // Constructor, destructor, assignment, swap
414  _Hashtable() = default;
415  _Hashtable(size_type __bucket_hint,
416  const _H1&, const _H2&, const _Hash&,
417  const _Equal&, const _ExtractKey&,
418  const allocator_type&);
419 
420  template<typename _InputIterator>
421  _Hashtable(_InputIterator __first, _InputIterator __last,
422  size_type __bucket_hint,
423  const _H1&, const _H2&, const _Hash&,
424  const _Equal&, const _ExtractKey&,
425  const allocator_type&);
426 
427  _Hashtable(const _Hashtable&);
428 
429  _Hashtable(_Hashtable&&) noexcept;
430 
431  _Hashtable(const _Hashtable&, const allocator_type&);
432 
433  _Hashtable(_Hashtable&&, const allocator_type&);
434 
435  // Use delegating constructors.
436  explicit
437  _Hashtable(const allocator_type& __a)
438  : __hashtable_alloc(__node_alloc_type(__a))
439  { }
440 
441  explicit
442  _Hashtable(size_type __n,
443  const _H1& __hf = _H1(),
444  const key_equal& __eql = key_equal(),
445  const allocator_type& __a = allocator_type())
446  : _Hashtable(__n, __hf, _H2(), _Hash(), __eql,
447  __key_extract(), __a)
448  { }
449 
450  template<typename _InputIterator>
451  _Hashtable(_InputIterator __f, _InputIterator __l,
452  size_type __n = 0,
453  const _H1& __hf = _H1(),
454  const key_equal& __eql = key_equal(),
455  const allocator_type& __a = allocator_type())
456  : _Hashtable(__f, __l, __n, __hf, _H2(), _Hash(), __eql,
457  __key_extract(), __a)
458  { }
459 
461  size_type __n = 0,
462  const _H1& __hf = _H1(),
463  const key_equal& __eql = key_equal(),
464  const allocator_type& __a = allocator_type())
465  : _Hashtable(__l.begin(), __l.end(), __n, __hf, _H2(), _Hash(), __eql,
466  __key_extract(), __a)
467  { }
468 
469  _Hashtable&
470  operator=(const _Hashtable& __ht);
471 
472  _Hashtable&
473  operator=(_Hashtable&& __ht)
474  noexcept(__node_alloc_traits::_S_nothrow_move()
477  {
478  constexpr bool __move_storage =
479  __node_alloc_traits::_S_propagate_on_move_assign()
480  || __node_alloc_traits::_S_always_equal();
481  _M_move_assign(std::move(__ht), __bool_constant<__move_storage>());
482  return *this;
483  }
484 
485  _Hashtable&
486  operator=(initializer_list<value_type> __l)
487  {
488  __reuse_or_alloc_node_type __roan(_M_begin(), *this);
489  _M_before_begin._M_nxt = nullptr;
490  clear();
491  this->_M_insert_range(__l.begin(), __l.end(), __roan, __unique_keys());
492  return *this;
493  }
494 
495  ~_Hashtable() noexcept;
496 
497  void
498  swap(_Hashtable&)
499  noexcept(__and_<__is_nothrow_swappable<_H1>,
500  __is_nothrow_swappable<_Equal>>::value);
501 
502  // Basic container operations
503  iterator
504  begin() noexcept
505  { return iterator(_M_begin()); }
506 
507  const_iterator
508  begin() const noexcept
509  { return const_iterator(_M_begin()); }
510 
511  iterator
512  end() noexcept
513  { return iterator(nullptr); }
514 
515  const_iterator
516  end() const noexcept
517  { return const_iterator(nullptr); }
518 
519  const_iterator
520  cbegin() const noexcept
521  { return const_iterator(_M_begin()); }
522 
523  const_iterator
524  cend() const noexcept
525  { return const_iterator(nullptr); }
526 
527  size_type
528  size() const noexcept
529  { return _M_element_count; }
530 
531  _GLIBCXX_NODISCARD bool
532  empty() const noexcept
533  { return size() == 0; }
534 
535  allocator_type
536  get_allocator() const noexcept
537  { return allocator_type(this->_M_node_allocator()); }
538 
539  size_type
540  max_size() const noexcept
541  { return __node_alloc_traits::max_size(this->_M_node_allocator()); }
542 
543  // Observers
544  key_equal
545  key_eq() const
546  { return this->_M_eq(); }
547 
548  // hash_function, if present, comes from _Hash_code_base.
549 
550  // Bucket operations
551  size_type
552  bucket_count() const noexcept
553  { return _M_bucket_count; }
554 
555  size_type
556  max_bucket_count() const noexcept
557  { return max_size(); }
558 
559  size_type
560  bucket_size(size_type __n) const
561  { return std::distance(begin(__n), end(__n)); }
562 
563  size_type
564  bucket(const key_type& __k) const
565  { return _M_bucket_index(__k, this->_M_hash_code(__k)); }
566 
567  local_iterator
568  begin(size_type __n)
569  {
570  return local_iterator(*this, _M_bucket_begin(__n),
571  __n, _M_bucket_count);
572  }
573 
574  local_iterator
575  end(size_type __n)
576  { return local_iterator(*this, nullptr, __n, _M_bucket_count); }
577 
578  const_local_iterator
579  begin(size_type __n) const
580  {
581  return const_local_iterator(*this, _M_bucket_begin(__n),
582  __n, _M_bucket_count);
583  }
584 
585  const_local_iterator
586  end(size_type __n) const
587  { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
588 
589  // DR 691.
590  const_local_iterator
591  cbegin(size_type __n) const
592  {
593  return const_local_iterator(*this, _M_bucket_begin(__n),
594  __n, _M_bucket_count);
595  }
596 
597  const_local_iterator
598  cend(size_type __n) const
599  { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
600 
601  float
602  load_factor() const noexcept
603  {
604  return static_cast<float>(size()) / static_cast<float>(bucket_count());
605  }
606 
607  // max_load_factor, if present, comes from _Rehash_base.
608 
609  // Generalization of max_load_factor. Extension, not found in
610  // TR1. Only useful if _RehashPolicy is something other than
611  // the default.
612  const _RehashPolicy&
613  __rehash_policy() const
614  { return _M_rehash_policy; }
615 
616  void
617  __rehash_policy(const _RehashPolicy& __pol)
618  { _M_rehash_policy = __pol; }
619 
620  // Lookup.
621  iterator
622  find(const key_type& __k);
623 
624  const_iterator
625  find(const key_type& __k) const;
626 
627  size_type
628  count(const key_type& __k) const;
629 
631  equal_range(const key_type& __k);
632 
634  equal_range(const key_type& __k) const;
635 
636  protected:
637  // Bucket index computation helpers.
638  size_type
639  _M_bucket_index(__node_type* __n) const noexcept
640  { return __hash_code_base::_M_bucket_index(__n, _M_bucket_count); }
641 
642  size_type
643  _M_bucket_index(const key_type& __k, __hash_code __c) const
644  { return __hash_code_base::_M_bucket_index(__k, __c, _M_bucket_count); }
645 
646  // Find and insert helper functions and types
647  // Find the node before the one matching the criteria.
648  __node_base*
649  _M_find_before_node(size_type, const key_type&, __hash_code) const;
650 
651  __node_type*
652  _M_find_node(size_type __bkt, const key_type& __key,
653  __hash_code __c) const
654  {
655  __node_base* __before_n = _M_find_before_node(__bkt, __key, __c);
656  if (__before_n)
657  return static_cast<__node_type*>(__before_n->_M_nxt);
658  return nullptr;
659  }
660 
661  // Insert a node at the beginning of a bucket.
662  void
663  _M_insert_bucket_begin(size_type, __node_type*);
664 
665  // Remove the bucket first node
666  void
667  _M_remove_bucket_begin(size_type __bkt, __node_type* __next_n,
668  size_type __next_bkt);
669 
670  // Get the node before __n in the bucket __bkt
671  __node_base*
672  _M_get_previous_node(size_type __bkt, __node_base* __n);
673 
674  // Insert node with hash code __code, in bucket bkt if no rehash (assumes
675  // no element with its key already present). Take ownership of the node,
676  // deallocate it on exception.
677  iterator
678  _M_insert_unique_node(size_type __bkt, __hash_code __code,
679  __node_type* __n, size_type __n_elt = 1);
680 
681  // Insert node with hash code __code. Take ownership of the node,
682  // deallocate it on exception.
683  iterator
684  _M_insert_multi_node(__node_type* __hint,
685  __hash_code __code, __node_type* __n);
686 
687  template<typename... _Args>
689  _M_emplace(std::true_type, _Args&&... __args);
690 
691  template<typename... _Args>
692  iterator
693  _M_emplace(std::false_type __uk, _Args&&... __args)
694  { return _M_emplace(cend(), __uk, std::forward<_Args>(__args)...); }
695 
696  // Emplace with hint, useless when keys are unique.
697  template<typename... _Args>
698  iterator
699  _M_emplace(const_iterator, std::true_type __uk, _Args&&... __args)
700  { return _M_emplace(__uk, std::forward<_Args>(__args)...).first; }
701 
702  template<typename... _Args>
703  iterator
704  _M_emplace(const_iterator, std::false_type, _Args&&... __args);
705 
706  template<typename _Arg, typename _NodeGenerator>
708  _M_insert(_Arg&&, const _NodeGenerator&, true_type, size_type = 1);
709 
710  template<typename _Arg, typename _NodeGenerator>
711  iterator
712  _M_insert(_Arg&& __arg, const _NodeGenerator& __node_gen,
713  false_type __uk)
714  {
715  return _M_insert(cend(), std::forward<_Arg>(__arg), __node_gen,
716  __uk);
717  }
718 
719  // Insert with hint, not used when keys are unique.
720  template<typename _Arg, typename _NodeGenerator>
721  iterator
722  _M_insert(const_iterator, _Arg&& __arg,
723  const _NodeGenerator& __node_gen, true_type __uk)
724  {
725  return
726  _M_insert(std::forward<_Arg>(__arg), __node_gen, __uk).first;
727  }
728 
729  // Insert with hint when keys are not unique.
730  template<typename _Arg, typename _NodeGenerator>
731  iterator
732  _M_insert(const_iterator, _Arg&&,
733  const _NodeGenerator&, false_type);
734 
735  size_type
736  _M_erase(std::true_type, const key_type&);
737 
738  size_type
739  _M_erase(std::false_type, const key_type&);
740 
741  iterator
742  _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n);
743 
744  public:
745  // Emplace
746  template<typename... _Args>
747  __ireturn_type
748  emplace(_Args&&... __args)
749  { return _M_emplace(__unique_keys(), std::forward<_Args>(__args)...); }
750 
751  template<typename... _Args>
752  iterator
753  emplace_hint(const_iterator __hint, _Args&&... __args)
754  {
755  return _M_emplace(__hint, __unique_keys(),
756  std::forward<_Args>(__args)...);
757  }
758 
759  // Insert member functions via inheritance.
760 
761  // Erase
762  iterator
763  erase(const_iterator);
764 
765  // LWG 2059.
766  iterator
767  erase(iterator __it)
768  { return erase(const_iterator(__it)); }
769 
770  size_type
771  erase(const key_type& __k)
772  { return _M_erase(__unique_keys(), __k); }
773 
774  iterator
775  erase(const_iterator, const_iterator);
776 
777  void
778  clear() noexcept;
779 
780  // Set number of buckets to be appropriate for container of n element.
781  void rehash(size_type __n);
782 
783  // DR 1189.
784  // reserve, if present, comes from _Rehash_base.
785 
786 #if __cplusplus > 201402L
787  /// Re-insert an extracted node into a container with unique keys.
788  insert_return_type
789  _M_reinsert_node(node_type&& __nh)
790  {
791  insert_return_type __ret;
792  if (__nh.empty())
793  __ret.position = end();
794  else
795  {
796  __glibcxx_assert(get_allocator() == __nh.get_allocator());
797 
798  const key_type& __k = __nh._M_key();
799  __hash_code __code = this->_M_hash_code(__k);
800  size_type __bkt = _M_bucket_index(__k, __code);
801  if (__node_type* __n = _M_find_node(__bkt, __k, __code))
802  {
803  __ret.node = std::move(__nh);
804  __ret.position = iterator(__n);
805  __ret.inserted = false;
806  }
807  else
808  {
809  __ret.position
810  = _M_insert_unique_node(__bkt, __code, __nh._M_ptr);
811  __nh._M_ptr = nullptr;
812  __ret.inserted = true;
813  }
814  }
815  return __ret;
816  }
817 
818  /// Re-insert an extracted node into a container with equivalent keys.
819  iterator
820  _M_reinsert_node_multi(const_iterator __hint, node_type&& __nh)
821  {
822  iterator __ret;
823  if (__nh.empty())
824  __ret = end();
825  else
826  {
827  __glibcxx_assert(get_allocator() == __nh.get_allocator());
828 
829  auto __code = this->_M_hash_code(__nh._M_key());
830  auto __node = std::exchange(__nh._M_ptr, nullptr);
831  // FIXME: this deallocates the node on exception.
832  __ret = _M_insert_multi_node(__hint._M_cur, __code, __node);
833  }
834  return __ret;
835  }
836 
837  /// Extract a node.
838  node_type
839  extract(const_iterator __pos)
840  {
841  __node_type* __n = __pos._M_cur;
842  size_t __bkt = _M_bucket_index(__n);
843 
844  // Look for previous node to unlink it from the erased one, this
845  // is why we need buckets to contain the before begin to make
846  // this search fast.
847  __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
848 
849  if (__prev_n == _M_buckets[__bkt])
850  _M_remove_bucket_begin(__bkt, __n->_M_next(),
851  __n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
852  else if (__n->_M_nxt)
853  {
854  size_type __next_bkt = _M_bucket_index(__n->_M_next());
855  if (__next_bkt != __bkt)
856  _M_buckets[__next_bkt] = __prev_n;
857  }
858 
859  __prev_n->_M_nxt = __n->_M_nxt;
860  __n->_M_nxt = nullptr;
861  --_M_element_count;
862  return { __n, this->_M_node_allocator() };
863  }
864 
865  /// Extract a node.
866  node_type
867  extract(const _Key& __k)
868  {
869  node_type __nh;
870  auto __pos = find(__k);
871  if (__pos != end())
872  __nh = extract(const_iterator(__pos));
873  return __nh;
874  }
875 
876  /// Merge from a compatible container into one with unique keys.
877  template<typename _Compatible_Hashtable>
878  void
879  _M_merge_unique(_Compatible_Hashtable& __src) noexcept
880  {
881  static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
882  node_type>, "Node types are compatible");
883  __glibcxx_assert(get_allocator() == __src.get_allocator());
884 
885  auto __n_elt = __src.size();
886  for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
887  {
888  auto __pos = __i++;
889  const key_type& __k = this->_M_extract()(__pos._M_cur->_M_v());
890  __hash_code __code = this->_M_hash_code(__k);
891  size_type __bkt = _M_bucket_index(__k, __code);
892  if (_M_find_node(__bkt, __k, __code) == nullptr)
893  {
894  auto __nh = __src.extract(__pos);
895  _M_insert_unique_node(__bkt, __code, __nh._M_ptr, __n_elt);
896  __nh._M_ptr = nullptr;
897  __n_elt = 1;
898  }
899  else if (__n_elt != 1)
900  --__n_elt;
901  }
902  }
903 
904  /// Merge from a compatible container into one with equivalent keys.
905  template<typename _Compatible_Hashtable>
906  void
907  _M_merge_multi(_Compatible_Hashtable& __src) noexcept
908  {
909  static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
910  node_type>, "Node types are compatible");
911  __glibcxx_assert(get_allocator() == __src.get_allocator());
912 
913  this->reserve(size() + __src.size());
914  for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
915  _M_reinsert_node_multi(cend(), __src.extract(__i++));
916  }
917 #endif // C++17
918 
919  private:
920  // Helper rehash method used when keys are unique.
921  void _M_rehash_aux(size_type __n, std::true_type);
922 
923  // Helper rehash method used when keys can be non-unique.
924  void _M_rehash_aux(size_type __n, std::false_type);
925 
926  // Unconditionally change size of bucket array to n, restore
927  // hash policy state to __state on exception.
928  void _M_rehash(size_type __n, const __rehash_state& __state);
929  };
930 
931 
932  // Definitions of class template _Hashtable's out-of-line member functions.
933  template<typename _Key, typename _Value,
934  typename _Alloc, typename _ExtractKey, typename _Equal,
935  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
936  typename _Traits>
937  auto
938  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
939  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
940  _M_bucket_begin(size_type __bkt) const
941  -> __node_type*
942  {
943  __node_base* __n = _M_buckets[__bkt];
944  return __n ? static_cast<__node_type*>(__n->_M_nxt) : nullptr;
945  }
946 
947  template<typename _Key, typename _Value,
948  typename _Alloc, typename _ExtractKey, typename _Equal,
949  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
950  typename _Traits>
951  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
952  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
953  _Hashtable(size_type __bucket_hint,
954  const _H1& __h1, const _H2& __h2, const _Hash& __h,
955  const _Equal& __eq, const _ExtractKey& __exk,
956  const allocator_type& __a)
957  : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
958  {
959  auto __bkt = _M_rehash_policy._M_next_bkt(__bucket_hint);
960  if (__bkt > _M_bucket_count)
961  {
962  _M_buckets = _M_allocate_buckets(__bkt);
963  _M_bucket_count = __bkt;
964  }
965  }
966 
967  template<typename _Key, typename _Value,
968  typename _Alloc, typename _ExtractKey, typename _Equal,
969  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
970  typename _Traits>
971  template<typename _InputIterator>
972  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
973  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
974  _Hashtable(_InputIterator __f, _InputIterator __l,
975  size_type __bucket_hint,
976  const _H1& __h1, const _H2& __h2, const _Hash& __h,
977  const _Equal& __eq, const _ExtractKey& __exk,
978  const allocator_type& __a)
979  : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
980  {
981  auto __nb_elems = __detail::__distance_fw(__f, __l);
982  auto __bkt_count =
983  _M_rehash_policy._M_next_bkt(
984  std::max(_M_rehash_policy._M_bkt_for_elements(__nb_elems),
985  __bucket_hint));
986 
987  if (__bkt_count > _M_bucket_count)
988  {
989  _M_buckets = _M_allocate_buckets(__bkt_count);
990  _M_bucket_count = __bkt_count;
991  }
992 
993  for (; __f != __l; ++__f)
994  this->insert(*__f);
995  }
996 
997  template<typename _Key, typename _Value,
998  typename _Alloc, typename _ExtractKey, typename _Equal,
999  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1000  typename _Traits>
1001  auto
1002  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1003  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1004  operator=(const _Hashtable& __ht)
1005  -> _Hashtable&
1006  {
1007  if (&__ht == this)
1008  return *this;
1009 
1010  if (__node_alloc_traits::_S_propagate_on_copy_assign())
1011  {
1012  auto& __this_alloc = this->_M_node_allocator();
1013  auto& __that_alloc = __ht._M_node_allocator();
1014  if (!__node_alloc_traits::_S_always_equal()
1015  && __this_alloc != __that_alloc)
1016  {
1017  // Replacement allocator cannot free existing storage.
1018  this->_M_deallocate_nodes(_M_begin());
1019  _M_before_begin._M_nxt = nullptr;
1020  _M_deallocate_buckets();
1021  _M_buckets = nullptr;
1022  std::__alloc_on_copy(__this_alloc, __that_alloc);
1023  __hashtable_base::operator=(__ht);
1024  _M_bucket_count = __ht._M_bucket_count;
1025  _M_element_count = __ht._M_element_count;
1026  _M_rehash_policy = __ht._M_rehash_policy;
1027  __try
1028  {
1029  _M_assign(__ht,
1030  [this](const __node_type* __n)
1031  { return this->_M_allocate_node(__n->_M_v()); });
1032  }
1033  __catch(...)
1034  {
1035  // _M_assign took care of deallocating all memory. Now we
1036  // must make sure this instance remains in a usable state.
1037  _M_reset();
1038  __throw_exception_again;
1039  }
1040  return *this;
1041  }
1042  std::__alloc_on_copy(__this_alloc, __that_alloc);
1043  }
1044 
1045  // Reuse allocated buckets and nodes.
1046  _M_assign_elements(__ht,
1047  [](const __reuse_or_alloc_node_type& __roan, const __node_type* __n)
1048  { return __roan(__n->_M_v()); });
1049  return *this;
1050  }
1051 
1052  template<typename _Key, typename _Value,
1053  typename _Alloc, typename _ExtractKey, typename _Equal,
1054  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1055  typename _Traits>
1056  template<typename _Ht, typename _NodeGenerator>
1057  void
1058  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1059  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1060  _M_assign_elements(_Ht&& __ht, const _NodeGenerator& __node_gen)
1061  {
1062  __bucket_type* __former_buckets = nullptr;
1063  std::size_t __former_bucket_count = _M_bucket_count;
1064  const __rehash_state& __former_state = _M_rehash_policy._M_state();
1065 
1066  if (_M_bucket_count != __ht._M_bucket_count)
1067  {
1068  __former_buckets = _M_buckets;
1069  _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
1070  _M_bucket_count = __ht._M_bucket_count;
1071  }
1072  else
1073  __builtin_memset(_M_buckets, 0,
1074  _M_bucket_count * sizeof(__bucket_type));
1075 
1076  __try
1077  {
1078  __hashtable_base::operator=(std::forward<_Ht>(__ht));
1079  _M_element_count = __ht._M_element_count;
1080  _M_rehash_policy = __ht._M_rehash_policy;
1081  __reuse_or_alloc_node_type __roan(_M_begin(), *this);
1082  _M_before_begin._M_nxt = nullptr;
1083  _M_assign(__ht,
1084  [&__node_gen, &__roan](__node_type* __n)
1085  { return __node_gen(__roan, __n); });
1086  if (__former_buckets)
1087  _M_deallocate_buckets(__former_buckets, __former_bucket_count);
1088  }
1089  __catch(...)
1090  {
1091  if (__former_buckets)
1092  {
1093  // Restore previous buckets.
1094  _M_deallocate_buckets();
1095  _M_rehash_policy._M_reset(__former_state);
1096  _M_buckets = __former_buckets;
1097  _M_bucket_count = __former_bucket_count;
1098  }
1099  __builtin_memset(_M_buckets, 0,
1100  _M_bucket_count * sizeof(__bucket_type));
1101  __throw_exception_again;
1102  }
1103  }
1104 
1105  template<typename _Key, typename _Value,
1106  typename _Alloc, typename _ExtractKey, typename _Equal,
1107  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1108  typename _Traits>
1109  template<typename _NodeGenerator>
1110  void
1111  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1112  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1113  _M_assign(const _Hashtable& __ht, const _NodeGenerator& __node_gen)
1114  {
1115  __bucket_type* __buckets = nullptr;
1116  if (!_M_buckets)
1117  _M_buckets = __buckets = _M_allocate_buckets(_M_bucket_count);
1118 
1119  __try
1120  {
1121  if (!__ht._M_before_begin._M_nxt)
1122  return;
1123 
1124  // First deal with the special first node pointed to by
1125  // _M_before_begin.
1126  __node_type* __ht_n = __ht._M_begin();
1127  __node_type* __this_n = __node_gen(__ht_n);
1128  this->_M_copy_code(__this_n, __ht_n);
1129  _M_before_begin._M_nxt = __this_n;
1130  _M_buckets[_M_bucket_index(__this_n)] = &_M_before_begin;
1131 
1132  // Then deal with other nodes.
1133  __node_base* __prev_n = __this_n;
1134  for (__ht_n = __ht_n->_M_next(); __ht_n; __ht_n = __ht_n->_M_next())
1135  {
1136  __this_n = __node_gen(__ht_n);
1137  __prev_n->_M_nxt = __this_n;
1138  this->_M_copy_code(__this_n, __ht_n);
1139  size_type __bkt = _M_bucket_index(__this_n);
1140  if (!_M_buckets[__bkt])
1141  _M_buckets[__bkt] = __prev_n;
1142  __prev_n = __this_n;
1143  }
1144  }
1145  __catch(...)
1146  {
1147  clear();
1148  if (__buckets)
1149  _M_deallocate_buckets();
1150  __throw_exception_again;
1151  }
1152  }
1153 
1154  template<typename _Key, typename _Value,
1155  typename _Alloc, typename _ExtractKey, typename _Equal,
1156  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1157  typename _Traits>
1158  void
1159  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1160  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1161  _M_reset() noexcept
1162  {
1163  _M_rehash_policy._M_reset();
1164  _M_bucket_count = 1;
1165  _M_single_bucket = nullptr;
1166  _M_buckets = &_M_single_bucket;
1167  _M_before_begin._M_nxt = nullptr;
1168  _M_element_count = 0;
1169  }
1170 
1171  template<typename _Key, typename _Value,
1172  typename _Alloc, typename _ExtractKey, typename _Equal,
1173  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1174  typename _Traits>
1175  void
1176  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1177  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1178  _M_move_assign(_Hashtable&& __ht, std::true_type)
1179  {
1180  this->_M_deallocate_nodes(_M_begin());
1181  _M_deallocate_buckets();
1182  __hashtable_base::operator=(std::move(__ht));
1183  _M_rehash_policy = __ht._M_rehash_policy;
1184  if (!__ht._M_uses_single_bucket())
1185  _M_buckets = __ht._M_buckets;
1186  else
1187  {
1188  _M_buckets = &_M_single_bucket;
1189  _M_single_bucket = __ht._M_single_bucket;
1190  }
1191  _M_bucket_count = __ht._M_bucket_count;
1192  _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
1193  _M_element_count = __ht._M_element_count;
1194  std::__alloc_on_move(this->_M_node_allocator(), __ht._M_node_allocator());
1195 
1196  // Fix buckets containing the _M_before_begin pointers that can't be
1197  // moved.
1198  if (_M_begin())
1199  _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1200  __ht._M_reset();
1201  }
1202 
1203  template<typename _Key, typename _Value,
1204  typename _Alloc, typename _ExtractKey, typename _Equal,
1205  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1206  typename _Traits>
1207  void
1208  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1209  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1210  _M_move_assign(_Hashtable&& __ht, std::false_type)
1211  {
1212  if (__ht._M_node_allocator() == this->_M_node_allocator())
1213  _M_move_assign(std::move(__ht), std::true_type());
1214  else
1215  {
1216  // Can't move memory, move elements then.
1217  _M_assign_elements(std::move(__ht),
1218  [](const __reuse_or_alloc_node_type& __roan, __node_type* __n)
1219  { return __roan(std::move_if_noexcept(__n->_M_v())); });
1220  __ht.clear();
1221  }
1222  }
1223 
1224  template<typename _Key, typename _Value,
1225  typename _Alloc, typename _ExtractKey, typename _Equal,
1226  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1227  typename _Traits>
1228  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1229  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1230  _Hashtable(const _Hashtable& __ht)
1231  : __hashtable_base(__ht),
1232  __map_base(__ht),
1233  __rehash_base(__ht),
1234  __hashtable_alloc(
1235  __node_alloc_traits::_S_select_on_copy(__ht._M_node_allocator())),
1236  _M_buckets(nullptr),
1237  _M_bucket_count(__ht._M_bucket_count),
1238  _M_element_count(__ht._M_element_count),
1239  _M_rehash_policy(__ht._M_rehash_policy)
1240  {
1241  _M_assign(__ht,
1242  [this](const __node_type* __n)
1243  { return this->_M_allocate_node(__n->_M_v()); });
1244  }
1245 
1246  template<typename _Key, typename _Value,
1247  typename _Alloc, typename _ExtractKey, typename _Equal,
1248  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1249  typename _Traits>
1250  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1251  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1252  _Hashtable(_Hashtable&& __ht) noexcept
1253  : __hashtable_base(__ht),
1254  __map_base(__ht),
1255  __rehash_base(__ht),
1256  __hashtable_alloc(std::move(__ht._M_base_alloc())),
1257  _M_buckets(__ht._M_buckets),
1258  _M_bucket_count(__ht._M_bucket_count),
1259  _M_before_begin(__ht._M_before_begin._M_nxt),
1260  _M_element_count(__ht._M_element_count),
1261  _M_rehash_policy(__ht._M_rehash_policy)
1262  {
1263  // Update, if necessary, buckets if __ht is using its single bucket.
1264  if (__ht._M_uses_single_bucket())
1265  {
1266  _M_buckets = &_M_single_bucket;
1267  _M_single_bucket = __ht._M_single_bucket;
1268  }
1269 
1270  // Update, if necessary, bucket pointing to before begin that hasn't
1271  // moved.
1272  if (_M_begin())
1273  _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1274 
1275  __ht._M_reset();
1276  }
1277 
1278  template<typename _Key, typename _Value,
1279  typename _Alloc, typename _ExtractKey, typename _Equal,
1280  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1281  typename _Traits>
1282  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1283  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1284  _Hashtable(const _Hashtable& __ht, const allocator_type& __a)
1285  : __hashtable_base(__ht),
1286  __map_base(__ht),
1287  __rehash_base(__ht),
1288  __hashtable_alloc(__node_alloc_type(__a)),
1289  _M_buckets(),
1290  _M_bucket_count(__ht._M_bucket_count),
1291  _M_element_count(__ht._M_element_count),
1292  _M_rehash_policy(__ht._M_rehash_policy)
1293  {
1294  _M_assign(__ht,
1295  [this](const __node_type* __n)
1296  { return this->_M_allocate_node(__n->_M_v()); });
1297  }
1298 
1299  template<typename _Key, typename _Value,
1300  typename _Alloc, typename _ExtractKey, typename _Equal,
1301  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1302  typename _Traits>
1303  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1304  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1305  _Hashtable(_Hashtable&& __ht, const allocator_type& __a)
1306  : __hashtable_base(__ht),
1307  __map_base(__ht),
1308  __rehash_base(__ht),
1309  __hashtable_alloc(__node_alloc_type(__a)),
1310  _M_buckets(nullptr),
1311  _M_bucket_count(__ht._M_bucket_count),
1312  _M_element_count(__ht._M_element_count),
1313  _M_rehash_policy(__ht._M_rehash_policy)
1314  {
1315  if (__ht._M_node_allocator() == this->_M_node_allocator())
1316  {
1317  if (__ht._M_uses_single_bucket())
1318  {
1319  _M_buckets = &_M_single_bucket;
1320  _M_single_bucket = __ht._M_single_bucket;
1321  }
1322  else
1323  _M_buckets = __ht._M_buckets;
1324 
1325  _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
1326  // Update, if necessary, bucket pointing to before begin that hasn't
1327  // moved.
1328  if (_M_begin())
1329  _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1330  __ht._M_reset();
1331  }
1332  else
1333  {
1334  _M_assign(__ht,
1335  [this](__node_type* __n)
1336  {
1337  return this->_M_allocate_node(
1338  std::move_if_noexcept(__n->_M_v()));
1339  });
1340  __ht.clear();
1341  }
1342  }
1343 
1344  template<typename _Key, typename _Value,
1345  typename _Alloc, typename _ExtractKey, typename _Equal,
1346  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1347  typename _Traits>
1348  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1349  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1350  ~_Hashtable() noexcept
1351  {
1352  clear();
1353  _M_deallocate_buckets();
1354  }
1355 
1356  template<typename _Key, typename _Value,
1357  typename _Alloc, typename _ExtractKey, typename _Equal,
1358  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1359  typename _Traits>
1360  void
1361  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1362  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1363  swap(_Hashtable& __x)
1364  noexcept(__and_<__is_nothrow_swappable<_H1>,
1365  __is_nothrow_swappable<_Equal>>::value)
1366  {
1367  // The only base class with member variables is hash_code_base.
1368  // We define _Hash_code_base::_M_swap because different
1369  // specializations have different members.
1370  this->_M_swap(__x);
1371 
1372  std::__alloc_on_swap(this->_M_node_allocator(), __x._M_node_allocator());
1373  std::swap(_M_rehash_policy, __x._M_rehash_policy);
1374 
1375  // Deal properly with potentially moved instances.
1376  if (this->_M_uses_single_bucket())
1377  {
1378  if (!__x._M_uses_single_bucket())
1379  {
1380  _M_buckets = __x._M_buckets;
1381  __x._M_buckets = &__x._M_single_bucket;
1382  }
1383  }
1384  else if (__x._M_uses_single_bucket())
1385  {
1386  __x._M_buckets = _M_buckets;
1387  _M_buckets = &_M_single_bucket;
1388  }
1389  else
1390  std::swap(_M_buckets, __x._M_buckets);
1391 
1392  std::swap(_M_bucket_count, __x._M_bucket_count);
1393  std::swap(_M_before_begin._M_nxt, __x._M_before_begin._M_nxt);
1394  std::swap(_M_element_count, __x._M_element_count);
1395  std::swap(_M_single_bucket, __x._M_single_bucket);
1396 
1397  // Fix buckets containing the _M_before_begin pointers that can't be
1398  // swapped.
1399  if (_M_begin())
1400  _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1401 
1402  if (__x._M_begin())
1403  __x._M_buckets[__x._M_bucket_index(__x._M_begin())]
1404  = &__x._M_before_begin;
1405  }
1406 
1407  template<typename _Key, typename _Value,
1408  typename _Alloc, typename _ExtractKey, typename _Equal,
1409  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1410  typename _Traits>
1411  auto
1412  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1413  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1414  find(const key_type& __k)
1415  -> iterator
1416  {
1417  __hash_code __code = this->_M_hash_code(__k);
1418  std::size_t __n = _M_bucket_index(__k, __code);
1419  __node_type* __p = _M_find_node(__n, __k, __code);
1420  return __p ? iterator(__p) : end();
1421  }
1422 
1423  template<typename _Key, typename _Value,
1424  typename _Alloc, typename _ExtractKey, typename _Equal,
1425  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1426  typename _Traits>
1427  auto
1428  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1429  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1430  find(const key_type& __k) const
1431  -> const_iterator
1432  {
1433  __hash_code __code = this->_M_hash_code(__k);
1434  std::size_t __n = _M_bucket_index(__k, __code);
1435  __node_type* __p = _M_find_node(__n, __k, __code);
1436  return __p ? const_iterator(__p) : end();
1437  }
1438 
1439  template<typename _Key, typename _Value,
1440  typename _Alloc, typename _ExtractKey, typename _Equal,
1441  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1442  typename _Traits>
1443  auto
1444  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1445  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1446  count(const key_type& __k) const
1447  -> size_type
1448  {
1449  __hash_code __code = this->_M_hash_code(__k);
1450  std::size_t __n = _M_bucket_index(__k, __code);
1451  __node_type* __p = _M_bucket_begin(__n);
1452  if (!__p)
1453  return 0;
1454 
1455  std::size_t __result = 0;
1456  for (;; __p = __p->_M_next())
1457  {
1458  if (this->_M_equals(__k, __code, __p))
1459  ++__result;
1460  else if (__result)
1461  // All equivalent values are next to each other, if we
1462  // found a non-equivalent value after an equivalent one it
1463  // means that we won't find any new equivalent value.
1464  break;
1465  if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
1466  break;
1467  }
1468  return __result;
1469  }
1470 
1471  template<typename _Key, typename _Value,
1472  typename _Alloc, typename _ExtractKey, typename _Equal,
1473  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1474  typename _Traits>
1475  auto
1476  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1477  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1478  equal_range(const key_type& __k)
1479  -> pair<iterator, iterator>
1480  {
1481  __hash_code __code = this->_M_hash_code(__k);
1482  std::size_t __n = _M_bucket_index(__k, __code);
1483  __node_type* __p = _M_find_node(__n, __k, __code);
1484 
1485  if (__p)
1486  {
1487  __node_type* __p1 = __p->_M_next();
1488  while (__p1 && _M_bucket_index(__p1) == __n
1489  && this->_M_equals(__k, __code, __p1))
1490  __p1 = __p1->_M_next();
1491 
1492  return std::make_pair(iterator(__p), iterator(__p1));
1493  }
1494  else
1495  return std::make_pair(end(), end());
1496  }
1497 
1498  template<typename _Key, typename _Value,
1499  typename _Alloc, typename _ExtractKey, typename _Equal,
1500  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1501  typename _Traits>
1502  auto
1503  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1504  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1505  equal_range(const key_type& __k) const
1506  -> pair<const_iterator, const_iterator>
1507  {
1508  __hash_code __code = this->_M_hash_code(__k);
1509  std::size_t __n = _M_bucket_index(__k, __code);
1510  __node_type* __p = _M_find_node(__n, __k, __code);
1511 
1512  if (__p)
1513  {
1514  __node_type* __p1 = __p->_M_next();
1515  while (__p1 && _M_bucket_index(__p1) == __n
1516  && this->_M_equals(__k, __code, __p1))
1517  __p1 = __p1->_M_next();
1518 
1519  return std::make_pair(const_iterator(__p), const_iterator(__p1));
1520  }
1521  else
1522  return std::make_pair(end(), end());
1523  }
1524 
1525  // Find the node whose key compares equal to k in the bucket n.
1526  // Return nullptr if no node is found.
1527  template<typename _Key, typename _Value,
1528  typename _Alloc, typename _ExtractKey, typename _Equal,
1529  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1530  typename _Traits>
1531  auto
1532  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1533  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1534  _M_find_before_node(size_type __n, const key_type& __k,
1535  __hash_code __code) const
1536  -> __node_base*
1537  {
1538  __node_base* __prev_p = _M_buckets[__n];
1539  if (!__prev_p)
1540  return nullptr;
1541 
1542  for (__node_type* __p = static_cast<__node_type*>(__prev_p->_M_nxt);;
1543  __p = __p->_M_next())
1544  {
1545  if (this->_M_equals(__k, __code, __p))
1546  return __prev_p;
1547 
1548  if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
1549  break;
1550  __prev_p = __p;
1551  }
1552  return nullptr;
1553  }
1554 
1555  template<typename _Key, typename _Value,
1556  typename _Alloc, typename _ExtractKey, typename _Equal,
1557  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1558  typename _Traits>
1559  void
1560  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1561  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1562  _M_insert_bucket_begin(size_type __bkt, __node_type* __node)
1563  {
1564  if (_M_buckets[__bkt])
1565  {
1566  // Bucket is not empty, we just need to insert the new node
1567  // after the bucket before begin.
1568  __node->_M_nxt = _M_buckets[__bkt]->_M_nxt;
1569  _M_buckets[__bkt]->_M_nxt = __node;
1570  }
1571  else
1572  {
1573  // The bucket is empty, the new node is inserted at the
1574  // beginning of the singly-linked list and the bucket will
1575  // contain _M_before_begin pointer.
1576  __node->_M_nxt = _M_before_begin._M_nxt;
1577  _M_before_begin._M_nxt = __node;
1578  if (__node->_M_nxt)
1579  // We must update former begin bucket that is pointing to
1580  // _M_before_begin.
1581  _M_buckets[_M_bucket_index(__node->_M_next())] = __node;
1582  _M_buckets[__bkt] = &_M_before_begin;
1583  }
1584  }
1585 
1586  template<typename _Key, typename _Value,
1587  typename _Alloc, typename _ExtractKey, typename _Equal,
1588  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1589  typename _Traits>
1590  void
1591  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1592  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1593  _M_remove_bucket_begin(size_type __bkt, __node_type* __next,
1594  size_type __next_bkt)
1595  {
1596  if (!__next || __next_bkt != __bkt)
1597  {
1598  // Bucket is now empty
1599  // First update next bucket if any
1600  if (__next)
1601  _M_buckets[__next_bkt] = _M_buckets[__bkt];
1602 
1603  // Second update before begin node if necessary
1604  if (&_M_before_begin == _M_buckets[__bkt])
1605  _M_before_begin._M_nxt = __next;
1606  _M_buckets[__bkt] = nullptr;
1607  }
1608  }
1609 
1610  template<typename _Key, typename _Value,
1611  typename _Alloc, typename _ExtractKey, typename _Equal,
1612  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1613  typename _Traits>
1614  auto
1615  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1616  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1617  _M_get_previous_node(size_type __bkt, __node_base* __n)
1618  -> __node_base*
1619  {
1620  __node_base* __prev_n = _M_buckets[__bkt];
1621  while (__prev_n->_M_nxt != __n)
1622  __prev_n = __prev_n->_M_nxt;
1623  return __prev_n;
1624  }
1625 
1626  template<typename _Key, typename _Value,
1627  typename _Alloc, typename _ExtractKey, typename _Equal,
1628  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1629  typename _Traits>
1630  template<typename... _Args>
1631  auto
1632  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1633  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1634  _M_emplace(std::true_type, _Args&&... __args)
1635  -> pair<iterator, bool>
1636  {
1637  // First build the node to get access to the hash code
1638  __node_type* __node = this->_M_allocate_node(std::forward<_Args>(__args)...);
1639  const key_type& __k = this->_M_extract()(__node->_M_v());
1640  __hash_code __code;
1641  __try
1642  {
1643  __code = this->_M_hash_code(__k);
1644  }
1645  __catch(...)
1646  {
1647  this->_M_deallocate_node(__node);
1648  __throw_exception_again;
1649  }
1650 
1651  size_type __bkt = _M_bucket_index(__k, __code);
1652  if (__node_type* __p = _M_find_node(__bkt, __k, __code))
1653  {
1654  // There is already an equivalent node, no insertion
1655  this->_M_deallocate_node(__node);
1656  return std::make_pair(iterator(__p), false);
1657  }
1658 
1659  // Insert the node
1660  return std::make_pair(_M_insert_unique_node(__bkt, __code, __node),
1661  true);
1662  }
1663 
1664  template<typename _Key, typename _Value,
1665  typename _Alloc, typename _ExtractKey, typename _Equal,
1666  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1667  typename _Traits>
1668  template<typename... _Args>
1669  auto
1670  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1671  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1672  _M_emplace(const_iterator __hint, std::false_type, _Args&&... __args)
1673  -> iterator
1674  {
1675  // First build the node to get its hash code.
1676  __node_type* __node =
1677  this->_M_allocate_node(std::forward<_Args>(__args)...);
1678 
1679  __hash_code __code;
1680  __try
1681  {
1682  __code = this->_M_hash_code(this->_M_extract()(__node->_M_v()));
1683  }
1684  __catch(...)
1685  {
1686  this->_M_deallocate_node(__node);
1687  __throw_exception_again;
1688  }
1689 
1690  return _M_insert_multi_node(__hint._M_cur, __code, __node);
1691  }
1692 
1693  template<typename _Key, typename _Value,
1694  typename _Alloc, typename _ExtractKey, typename _Equal,
1695  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1696  typename _Traits>
1697  auto
1698  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1699  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1700  _M_insert_unique_node(size_type __bkt, __hash_code __code,
1701  __node_type* __node, size_type __n_elt)
1702  -> iterator
1703  {
1704  const __rehash_state& __saved_state = _M_rehash_policy._M_state();
1705  std::pair<bool, std::size_t> __do_rehash
1706  = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count,
1707  __n_elt);
1708 
1709  __try
1710  {
1711  if (__do_rehash.first)
1712  {
1713  _M_rehash(__do_rehash.second, __saved_state);
1714  __bkt = _M_bucket_index(this->_M_extract()(__node->_M_v()), __code);
1715  }
1716 
1717  this->_M_store_code(__node, __code);
1718 
1719  // Always insert at the beginning of the bucket.
1720  _M_insert_bucket_begin(__bkt, __node);
1721  ++_M_element_count;
1722  return iterator(__node);
1723  }
1724  __catch(...)
1725  {
1726  this->_M_deallocate_node(__node);
1727  __throw_exception_again;
1728  }
1729  }
1730 
1731  // Insert node, in bucket bkt if no rehash (assumes no element with its key
1732  // already present). Take ownership of the node, deallocate it on exception.
1733  template<typename _Key, typename _Value,
1734  typename _Alloc, typename _ExtractKey, typename _Equal,
1735  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1736  typename _Traits>
1737  auto
1738  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1739  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1740  _M_insert_multi_node(__node_type* __hint, __hash_code __code,
1741  __node_type* __node)
1742  -> iterator
1743  {
1744  const __rehash_state& __saved_state = _M_rehash_policy._M_state();
1745  std::pair<bool, std::size_t> __do_rehash
1746  = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count, 1);
1747 
1748  __try
1749  {
1750  if (__do_rehash.first)
1751  _M_rehash(__do_rehash.second, __saved_state);
1752 
1753  this->_M_store_code(__node, __code);
1754  const key_type& __k = this->_M_extract()(__node->_M_v());
1755  size_type __bkt = _M_bucket_index(__k, __code);
1756 
1757  // Find the node before an equivalent one or use hint if it exists and
1758  // if it is equivalent.
1759  __node_base* __prev
1760  = __builtin_expect(__hint != nullptr, false)
1761  && this->_M_equals(__k, __code, __hint)
1762  ? __hint
1763  : _M_find_before_node(__bkt, __k, __code);
1764  if (__prev)
1765  {
1766  // Insert after the node before the equivalent one.
1767  __node->_M_nxt = __prev->_M_nxt;
1768  __prev->_M_nxt = __node;
1769  if (__builtin_expect(__prev == __hint, false))
1770  // hint might be the last bucket node, in this case we need to
1771  // update next bucket.
1772  if (__node->_M_nxt
1773  && !this->_M_equals(__k, __code, __node->_M_next()))
1774  {
1775  size_type __next_bkt = _M_bucket_index(__node->_M_next());
1776  if (__next_bkt != __bkt)
1777  _M_buckets[__next_bkt] = __node;
1778  }
1779  }
1780  else
1781  // The inserted node has no equivalent in the
1782  // hashtable. We must insert the new node at the
1783  // beginning of the bucket to preserve equivalent
1784  // elements' relative positions.
1785  _M_insert_bucket_begin(__bkt, __node);
1786  ++_M_element_count;
1787  return iterator(__node);
1788  }
1789  __catch(...)
1790  {
1791  this->_M_deallocate_node(__node);
1792  __throw_exception_again;
1793  }
1794  }
1795 
1796  // Insert v if no element with its key is already present.
1797  template<typename _Key, typename _Value,
1798  typename _Alloc, typename _ExtractKey, typename _Equal,
1799  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1800  typename _Traits>
1801  template<typename _Arg, typename _NodeGenerator>
1802  auto
1803  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1804  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1805  _M_insert(_Arg&& __v, const _NodeGenerator& __node_gen, true_type,
1806  size_type __n_elt)
1807  -> pair<iterator, bool>
1808  {
1809  const key_type& __k = this->_M_extract()(__v);
1810  __hash_code __code = this->_M_hash_code(__k);
1811  size_type __bkt = _M_bucket_index(__k, __code);
1812 
1813  __node_type* __n = _M_find_node(__bkt, __k, __code);
1814  if (__n)
1815  return std::make_pair(iterator(__n), false);
1816 
1817  __n = __node_gen(std::forward<_Arg>(__v));
1818  return { _M_insert_unique_node(__bkt, __code, __n, __n_elt), true };
1819  }
1820 
1821  // Insert v unconditionally.
1822  template<typename _Key, typename _Value,
1823  typename _Alloc, typename _ExtractKey, typename _Equal,
1824  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1825  typename _Traits>
1826  template<typename _Arg, typename _NodeGenerator>
1827  auto
1828  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1829  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1830  _M_insert(const_iterator __hint, _Arg&& __v,
1831  const _NodeGenerator& __node_gen, false_type)
1832  -> iterator
1833  {
1834  // First compute the hash code so that we don't do anything if it
1835  // throws.
1836  __hash_code __code = this->_M_hash_code(this->_M_extract()(__v));
1837 
1838  // Second allocate new node so that we don't rehash if it throws.
1839  __node_type* __node = __node_gen(std::forward<_Arg>(__v));
1840 
1841  return _M_insert_multi_node(__hint._M_cur, __code, __node);
1842  }
1843 
1844  template<typename _Key, typename _Value,
1845  typename _Alloc, typename _ExtractKey, typename _Equal,
1846  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1847  typename _Traits>
1848  auto
1849  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1850  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1851  erase(const_iterator __it)
1852  -> iterator
1853  {
1854  __node_type* __n = __it._M_cur;
1855  std::size_t __bkt = _M_bucket_index(__n);
1856 
1857  // Look for previous node to unlink it from the erased one, this
1858  // is why we need buckets to contain the before begin to make
1859  // this search fast.
1860  __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
1861  return _M_erase(__bkt, __prev_n, __n);
1862  }
1863 
1864  template<typename _Key, typename _Value,
1865  typename _Alloc, typename _ExtractKey, typename _Equal,
1866  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1867  typename _Traits>
1868  auto
1869  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1870  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1871  _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n)
1872  -> iterator
1873  {
1874  if (__prev_n == _M_buckets[__bkt])
1875  _M_remove_bucket_begin(__bkt, __n->_M_next(),
1876  __n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
1877  else if (__n->_M_nxt)
1878  {
1879  size_type __next_bkt = _M_bucket_index(__n->_M_next());
1880  if (__next_bkt != __bkt)
1881  _M_buckets[__next_bkt] = __prev_n;
1882  }
1883 
1884  __prev_n->_M_nxt = __n->_M_nxt;
1885  iterator __result(__n->_M_next());
1886  this->_M_deallocate_node(__n);
1887  --_M_element_count;
1888 
1889  return __result;
1890  }
1891 
1892  template<typename _Key, typename _Value,
1893  typename _Alloc, typename _ExtractKey, typename _Equal,
1894  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1895  typename _Traits>
1896  auto
1897  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1898  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1899  _M_erase(std::true_type, const key_type& __k)
1900  -> size_type
1901  {
1902  __hash_code __code = this->_M_hash_code(__k);
1903  std::size_t __bkt = _M_bucket_index(__k, __code);
1904 
1905  // Look for the node before the first matching node.
1906  __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
1907  if (!__prev_n)
1908  return 0;
1909 
1910  // We found a matching node, erase it.
1911  __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
1912  _M_erase(__bkt, __prev_n, __n);
1913  return 1;
1914  }
1915 
1916  template<typename _Key, typename _Value,
1917  typename _Alloc, typename _ExtractKey, typename _Equal,
1918  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1919  typename _Traits>
1920  auto
1921  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1922  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1923  _M_erase(std::false_type, const key_type& __k)
1924  -> size_type
1925  {
1926  __hash_code __code = this->_M_hash_code(__k);
1927  std::size_t __bkt = _M_bucket_index(__k, __code);
1928 
1929  // Look for the node before the first matching node.
1930  __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
1931  if (!__prev_n)
1932  return 0;
1933 
1934  // _GLIBCXX_RESOLVE_LIB_DEFECTS
1935  // 526. Is it undefined if a function in the standard changes
1936  // in parameters?
1937  // We use one loop to find all matching nodes and another to deallocate
1938  // them so that the key stays valid during the first loop. It might be
1939  // invalidated indirectly when destroying nodes.
1940  __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
1941  __node_type* __n_last = __n;
1942  std::size_t __n_last_bkt = __bkt;
1943  do
1944  {
1945  __n_last = __n_last->_M_next();
1946  if (!__n_last)
1947  break;
1948  __n_last_bkt = _M_bucket_index(__n_last);
1949  }
1950  while (__n_last_bkt == __bkt && this->_M_equals(__k, __code, __n_last));
1951 
1952  // Deallocate nodes.
1953  size_type __result = 0;
1954  do
1955  {
1956  __node_type* __p = __n->_M_next();
1957  this->_M_deallocate_node(__n);
1958  __n = __p;
1959  ++__result;
1960  --_M_element_count;
1961  }
1962  while (__n != __n_last);
1963 
1964  if (__prev_n == _M_buckets[__bkt])
1965  _M_remove_bucket_begin(__bkt, __n_last, __n_last_bkt);
1966  else if (__n_last && __n_last_bkt != __bkt)
1967  _M_buckets[__n_last_bkt] = __prev_n;
1968  __prev_n->_M_nxt = __n_last;
1969  return __result;
1970  }
1971 
1972  template<typename _Key, typename _Value,
1973  typename _Alloc, typename _ExtractKey, typename _Equal,
1974  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1975  typename _Traits>
1976  auto
1977  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1978  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1979  erase(const_iterator __first, const_iterator __last)
1980  -> iterator
1981  {
1982  __node_type* __n = __first._M_cur;
1983  __node_type* __last_n = __last._M_cur;
1984  if (__n == __last_n)
1985  return iterator(__n);
1986 
1987  std::size_t __bkt = _M_bucket_index(__n);
1988 
1989  __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
1990  bool __is_bucket_begin = __n == _M_bucket_begin(__bkt);
1991  std::size_t __n_bkt = __bkt;
1992  for (;;)
1993  {
1994  do
1995  {
1996  __node_type* __tmp = __n;
1997  __n = __n->_M_next();
1998  this->_M_deallocate_node(__tmp);
1999  --_M_element_count;
2000  if (!__n)
2001  break;
2002  __n_bkt = _M_bucket_index(__n);
2003  }
2004  while (__n != __last_n && __n_bkt == __bkt);
2005  if (__is_bucket_begin)
2006  _M_remove_bucket_begin(__bkt, __n, __n_bkt);
2007  if (__n == __last_n)
2008  break;
2009  __is_bucket_begin = true;
2010  __bkt = __n_bkt;
2011  }
2012 
2013  if (__n && (__n_bkt != __bkt || __is_bucket_begin))
2014  _M_buckets[__n_bkt] = __prev_n;
2015  __prev_n->_M_nxt = __n;
2016  return iterator(__n);
2017  }
2018 
2019  template<typename _Key, typename _Value,
2020  typename _Alloc, typename _ExtractKey, typename _Equal,
2021  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2022  typename _Traits>
2023  void
2024  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2025  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2026  clear() noexcept
2027  {
2028  this->_M_deallocate_nodes(_M_begin());
2029  __builtin_memset(_M_buckets, 0, _M_bucket_count * sizeof(__bucket_type));
2030  _M_element_count = 0;
2031  _M_before_begin._M_nxt = nullptr;
2032  }
2033 
2034  template<typename _Key, typename _Value,
2035  typename _Alloc, typename _ExtractKey, typename _Equal,
2036  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2037  typename _Traits>
2038  void
2039  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2040  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2041  rehash(size_type __n)
2042  {
2043  const __rehash_state& __saved_state = _M_rehash_policy._M_state();
2044  std::size_t __buckets
2045  = std::max(_M_rehash_policy._M_bkt_for_elements(_M_element_count + 1),
2046  __n);
2047  __buckets = _M_rehash_policy._M_next_bkt(__buckets);
2048 
2049  if (__buckets != _M_bucket_count)
2050  _M_rehash(__buckets, __saved_state);
2051  else
2052  // No rehash, restore previous state to keep a consistent state.
2053  _M_rehash_policy._M_reset(__saved_state);
2054  }
2055 
2056  template<typename _Key, typename _Value,
2057  typename _Alloc, typename _ExtractKey, typename _Equal,
2058  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2059  typename _Traits>
2060  void
2061  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2062  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2063  _M_rehash(size_type __n, const __rehash_state& __state)
2064  {
2065  __try
2066  {
2067  _M_rehash_aux(__n, __unique_keys());
2068  }
2069  __catch(...)
2070  {
2071  // A failure here means that buckets allocation failed. We only
2072  // have to restore hash policy previous state.
2073  _M_rehash_policy._M_reset(__state);
2074  __throw_exception_again;
2075  }
2076  }
2077 
2078  // Rehash when there is no equivalent elements.
2079  template<typename _Key, typename _Value,
2080  typename _Alloc, typename _ExtractKey, typename _Equal,
2081  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2082  typename _Traits>
2083  void
2084  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2085  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2086  _M_rehash_aux(size_type __n, std::true_type)
2087  {
2088  __bucket_type* __new_buckets = _M_allocate_buckets(__n);
2089  __node_type* __p = _M_begin();
2090  _M_before_begin._M_nxt = nullptr;
2091  std::size_t __bbegin_bkt = 0;
2092  while (__p)
2093  {
2094  __node_type* __next = __p->_M_next();
2095  std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
2096  if (!__new_buckets[__bkt])
2097  {
2098  __p->_M_nxt = _M_before_begin._M_nxt;
2099  _M_before_begin._M_nxt = __p;
2100  __new_buckets[__bkt] = &_M_before_begin;
2101  if (__p->_M_nxt)
2102  __new_buckets[__bbegin_bkt] = __p;
2103  __bbegin_bkt = __bkt;
2104  }
2105  else
2106  {
2107  __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2108  __new_buckets[__bkt]->_M_nxt = __p;
2109  }
2110  __p = __next;
2111  }
2112 
2113  _M_deallocate_buckets();
2114  _M_bucket_count = __n;
2115  _M_buckets = __new_buckets;
2116  }
2117 
2118  // Rehash when there can be equivalent elements, preserve their relative
2119  // order.
2120  template<typename _Key, typename _Value,
2121  typename _Alloc, typename _ExtractKey, typename _Equal,
2122  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2123  typename _Traits>
2124  void
2125  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2126  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2127  _M_rehash_aux(size_type __n, std::false_type)
2128  {
2129  __bucket_type* __new_buckets = _M_allocate_buckets(__n);
2130 
2131  __node_type* __p = _M_begin();
2132  _M_before_begin._M_nxt = nullptr;
2133  std::size_t __bbegin_bkt = 0;
2134  std::size_t __prev_bkt = 0;
2135  __node_type* __prev_p = nullptr;
2136  bool __check_bucket = false;
2137 
2138  while (__p)
2139  {
2140  __node_type* __next = __p->_M_next();
2141  std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
2142 
2143  if (__prev_p && __prev_bkt == __bkt)
2144  {
2145  // Previous insert was already in this bucket, we insert after
2146  // the previously inserted one to preserve equivalent elements
2147  // relative order.
2148  __p->_M_nxt = __prev_p->_M_nxt;
2149  __prev_p->_M_nxt = __p;
2150 
2151  // Inserting after a node in a bucket require to check that we
2152  // haven't change the bucket last node, in this case next
2153  // bucket containing its before begin node must be updated. We
2154  // schedule a check as soon as we move out of the sequence of
2155  // equivalent nodes to limit the number of checks.
2156  __check_bucket = true;
2157  }
2158  else
2159  {
2160  if (__check_bucket)
2161  {
2162  // Check if we shall update the next bucket because of
2163  // insertions into __prev_bkt bucket.
2164  if (__prev_p->_M_nxt)
2165  {
2166  std::size_t __next_bkt
2167  = __hash_code_base::_M_bucket_index(__prev_p->_M_next(),
2168  __n);
2169  if (__next_bkt != __prev_bkt)
2170  __new_buckets[__next_bkt] = __prev_p;
2171  }
2172  __check_bucket = false;
2173  }
2174 
2175  if (!__new_buckets[__bkt])
2176  {
2177  __p->_M_nxt = _M_before_begin._M_nxt;
2178  _M_before_begin._M_nxt = __p;
2179  __new_buckets[__bkt] = &_M_before_begin;
2180  if (__p->_M_nxt)
2181  __new_buckets[__bbegin_bkt] = __p;
2182  __bbegin_bkt = __bkt;
2183  }
2184  else
2185  {
2186  __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2187  __new_buckets[__bkt]->_M_nxt = __p;
2188  }
2189  }
2190  __prev_p = __p;
2191  __prev_bkt = __bkt;
2192  __p = __next;
2193  }
2194 
2195  if (__check_bucket && __prev_p->_M_nxt)
2196  {
2197  std::size_t __next_bkt
2198  = __hash_code_base::_M_bucket_index(__prev_p->_M_next(), __n);
2199  if (__next_bkt != __prev_bkt)
2200  __new_buckets[__next_bkt] = __prev_p;
2201  }
2202 
2203  _M_deallocate_buckets();
2204  _M_bucket_count = __n;
2205  _M_buckets = __new_buckets;
2206  }
2207 
2208 #if __cplusplus > 201402L
2209  template<typename, typename, typename> class _Hash_merge_helper { };
2210 #endif // C++17
2211 
2212 #if __cpp_deduction_guides >= 201606
2213  // Used to constrain deduction guides
2214  template<typename _Hash>
2215  using _RequireNotAllocatorOrIntegral
2216  = __enable_if_t<!__or_<is_integral<_Hash>, __is_allocator<_Hash>>::value>;
2217 #endif
2218 
2219 _GLIBCXX_END_NAMESPACE_VERSION
2220 } // namespace std
2221 
2222 #endif // _HASHTABLE_H
constexpr const _Tp * end(initializer_list< _Tp > __ils) noexcept
Return an iterator pointing to one past the last element of the initializer_list. ...
_T2 second
first is a copy of the first object
Definition: stl_pair.h:215
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
Definition: type_traits:78
_Tp exchange(_Tp &__obj, _Up &&__new_val)
Assign __new_val to __obj and return its previous value.
Definition: utility:286
ISO C++ entities toplevel namespace is std.
constexpr conditional< __move_if_noexcept_cond< _Tp >::value, const _Tp &, _Tp && >::type move_if_noexcept(_Tp &__x) noexcept
Conditionally convert a value to an rvalue.
Definition: move.h:119
is_default_constructible
Definition: type_traits:889
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition: type_traits:75
Define a member typedef type to one of two argument types.
Definition: type_traits:92
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:127
_T1 first
second_type is the second bound type
Definition: stl_pair.h:214
is_nothrow_move_assignable
Definition: type_traits:1101
constexpr const _Tp * begin(initializer_list< _Tp > __ils) noexcept
Return an iterator pointing to the first element of the initializer_list.
integral_constant
Definition: type_traits:57
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:116
initializer_list
is_same
Definition: type_traits:1292
Uniform interface to C++98 and C++11 allocators.
Node const_iterators, used to iterate through all the hashtable.
constexpr pair< typename __decay_and_strip< _T1 >::__type, typename __decay_and_strip< _T2 >::__type > make_pair(_T1 &&__x, _T2 &&__y)
A convenience wrapper for creating a pair from two objects.
Definition: stl_pair.h:524
_GLIBCXX17_CONSTEXPR iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
Struct holding two objects of arbitrary type.
Definition: stl_pair.h:208
_GLIBCXX14_CONSTEXPR const _Tp & max(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:222
Node iterators, used to iterate through all the hashtable.