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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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  template<bool _No_realloc = true>
413  static constexpr bool
414  _S_nothrow_move()
415  {
416 #if __cplusplus <= 201402L
417  return __and_<__bool_constant<_No_realloc>,
420 #else
421  if constexpr (_No_realloc)
422  if constexpr (is_nothrow_copy_constructible<_H1>())
424  return false;
425 #endif
426  }
427 
428  _Hashtable(_Hashtable&& __ht, __node_alloc_type&& __a,
429  true_type /* alloc always equal */)
430  noexcept(_S_nothrow_move());
431 
432  _Hashtable(_Hashtable&&, __node_alloc_type&&,
433  false_type /* alloc always equal */);
434 
435 
436  public:
437  // Constructor, destructor, assignment, swap
438  _Hashtable() = default;
439  _Hashtable(size_type __bucket_hint,
440  const _H1&, const _H2&, const _Hash&,
441  const _Equal&, const _ExtractKey&,
442  const allocator_type&);
443 
444  template<typename _InputIterator>
445  _Hashtable(_InputIterator __first, _InputIterator __last,
446  size_type __bucket_hint,
447  const _H1&, const _H2&, const _Hash&,
448  const _Equal&, const _ExtractKey&,
449  const allocator_type&);
450 
451  _Hashtable(const _Hashtable&);
452 
453  _Hashtable(_Hashtable&& __ht)
454  noexcept(_S_nothrow_move())
455  : _Hashtable(std::move(__ht), std::move(__ht._M_node_allocator()),
456  true_type{})
457  { }
458 
459  _Hashtable(const _Hashtable&, const allocator_type&);
460 
461  _Hashtable(_Hashtable&& __ht, const allocator_type& __a)
462  noexcept(_S_nothrow_move<__node_alloc_traits::_S_always_equal()>())
463  : _Hashtable(std::move(__ht), __node_alloc_type(__a),
464  typename __node_alloc_traits::is_always_equal{})
465  { }
466 
467  // Use delegating constructors.
468  explicit
469  _Hashtable(const allocator_type& __a)
470  : __hashtable_alloc(__node_alloc_type(__a))
471  { }
472 
473  explicit
474  _Hashtable(size_type __n,
475  const _H1& __hf = _H1(),
476  const key_equal& __eql = key_equal(),
477  const allocator_type& __a = allocator_type())
478  : _Hashtable(__n, __hf, _H2(), _Hash(), __eql,
479  __key_extract(), __a)
480  { }
481 
482  template<typename _InputIterator>
483  _Hashtable(_InputIterator __f, _InputIterator __l,
484  size_type __n = 0,
485  const _H1& __hf = _H1(),
486  const key_equal& __eql = key_equal(),
487  const allocator_type& __a = allocator_type())
488  : _Hashtable(__f, __l, __n, __hf, _H2(), _Hash(), __eql,
489  __key_extract(), __a)
490  { }
491 
493  size_type __n = 0,
494  const _H1& __hf = _H1(),
495  const key_equal& __eql = key_equal(),
496  const allocator_type& __a = allocator_type())
497  : _Hashtable(__l.begin(), __l.end(), __n, __hf, _H2(), _Hash(), __eql,
498  __key_extract(), __a)
499  { }
500 
501  _Hashtable&
502  operator=(const _Hashtable& __ht);
503 
504  _Hashtable&
505  operator=(_Hashtable&& __ht)
506  noexcept(__node_alloc_traits::_S_nothrow_move()
509  {
510  constexpr bool __move_storage =
511  __node_alloc_traits::_S_propagate_on_move_assign()
512  || __node_alloc_traits::_S_always_equal();
513  _M_move_assign(std::move(__ht), __bool_constant<__move_storage>());
514  return *this;
515  }
516 
517  _Hashtable&
518  operator=(initializer_list<value_type> __l)
519  {
520  __reuse_or_alloc_node_type __roan(_M_begin(), *this);
521  _M_before_begin._M_nxt = nullptr;
522  clear();
523  this->_M_insert_range(__l.begin(), __l.end(), __roan, __unique_keys());
524  return *this;
525  }
526 
527  ~_Hashtable() noexcept;
528 
529  void
530  swap(_Hashtable&)
531  noexcept(__and_<__is_nothrow_swappable<_H1>,
532  __is_nothrow_swappable<_Equal>>::value);
533 
534  // Basic container operations
535  iterator
536  begin() noexcept
537  { return iterator(_M_begin()); }
538 
539  const_iterator
540  begin() const noexcept
541  { return const_iterator(_M_begin()); }
542 
543  iterator
544  end() noexcept
545  { return iterator(nullptr); }
546 
547  const_iterator
548  end() const noexcept
549  { return const_iterator(nullptr); }
550 
551  const_iterator
552  cbegin() const noexcept
553  { return const_iterator(_M_begin()); }
554 
555  const_iterator
556  cend() const noexcept
557  { return const_iterator(nullptr); }
558 
559  size_type
560  size() const noexcept
561  { return _M_element_count; }
562 
563  _GLIBCXX_NODISCARD bool
564  empty() const noexcept
565  { return size() == 0; }
566 
567  allocator_type
568  get_allocator() const noexcept
569  { return allocator_type(this->_M_node_allocator()); }
570 
571  size_type
572  max_size() const noexcept
573  { return __node_alloc_traits::max_size(this->_M_node_allocator()); }
574 
575  // Observers
576  key_equal
577  key_eq() const
578  { return this->_M_eq(); }
579 
580  // hash_function, if present, comes from _Hash_code_base.
581 
582  // Bucket operations
583  size_type
584  bucket_count() const noexcept
585  { return _M_bucket_count; }
586 
587  size_type
588  max_bucket_count() const noexcept
589  { return max_size(); }
590 
591  size_type
592  bucket_size(size_type __n) const
593  { return std::distance(begin(__n), end(__n)); }
594 
595  size_type
596  bucket(const key_type& __k) const
597  { return _M_bucket_index(__k, this->_M_hash_code(__k)); }
598 
599  local_iterator
600  begin(size_type __n)
601  {
602  return local_iterator(*this, _M_bucket_begin(__n),
603  __n, _M_bucket_count);
604  }
605 
606  local_iterator
607  end(size_type __n)
608  { return local_iterator(*this, nullptr, __n, _M_bucket_count); }
609 
610  const_local_iterator
611  begin(size_type __n) const
612  {
613  return const_local_iterator(*this, _M_bucket_begin(__n),
614  __n, _M_bucket_count);
615  }
616 
617  const_local_iterator
618  end(size_type __n) const
619  { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
620 
621  // DR 691.
622  const_local_iterator
623  cbegin(size_type __n) const
624  {
625  return const_local_iterator(*this, _M_bucket_begin(__n),
626  __n, _M_bucket_count);
627  }
628 
629  const_local_iterator
630  cend(size_type __n) const
631  { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
632 
633  float
634  load_factor() const noexcept
635  {
636  return static_cast<float>(size()) / static_cast<float>(bucket_count());
637  }
638 
639  // max_load_factor, if present, comes from _Rehash_base.
640 
641  // Generalization of max_load_factor. Extension, not found in
642  // TR1. Only useful if _RehashPolicy is something other than
643  // the default.
644  const _RehashPolicy&
645  __rehash_policy() const
646  { return _M_rehash_policy; }
647 
648  void
649  __rehash_policy(const _RehashPolicy& __pol)
650  { _M_rehash_policy = __pol; }
651 
652  // Lookup.
653  iterator
654  find(const key_type& __k);
655 
656  const_iterator
657  find(const key_type& __k) const;
658 
659  size_type
660  count(const key_type& __k) const;
661 
663  equal_range(const key_type& __k);
664 
666  equal_range(const key_type& __k) const;
667 
668  protected:
669  // Bucket index computation helpers.
670  size_type
671  _M_bucket_index(__node_type* __n) const noexcept
672  { return __hash_code_base::_M_bucket_index(__n, _M_bucket_count); }
673 
674  size_type
675  _M_bucket_index(const key_type& __k, __hash_code __c) const
676  { return __hash_code_base::_M_bucket_index(__k, __c, _M_bucket_count); }
677 
678  // Find and insert helper functions and types
679  // Find the node before the one matching the criteria.
680  __node_base*
681  _M_find_before_node(size_type, const key_type&, __hash_code) const;
682 
683  __node_type*
684  _M_find_node(size_type __bkt, const key_type& __key,
685  __hash_code __c) const
686  {
687  __node_base* __before_n = _M_find_before_node(__bkt, __key, __c);
688  if (__before_n)
689  return static_cast<__node_type*>(__before_n->_M_nxt);
690  return nullptr;
691  }
692 
693  // Insert a node at the beginning of a bucket.
694  void
695  _M_insert_bucket_begin(size_type, __node_type*);
696 
697  // Remove the bucket first node
698  void
699  _M_remove_bucket_begin(size_type __bkt, __node_type* __next_n,
700  size_type __next_bkt);
701 
702  // Get the node before __n in the bucket __bkt
703  __node_base*
704  _M_get_previous_node(size_type __bkt, __node_base* __n);
705 
706  // Insert node with hash code __code, in bucket bkt if no rehash (assumes
707  // no element with its key already present). Take ownership of the node,
708  // deallocate it on exception.
709  iterator
710  _M_insert_unique_node(size_type __bkt, __hash_code __code,
711  __node_type* __n, size_type __n_elt = 1);
712 
713  // Insert node with hash code __code. Take ownership of the node,
714  // deallocate it on exception.
715  iterator
716  _M_insert_multi_node(__node_type* __hint,
717  __hash_code __code, __node_type* __n);
718 
719  template<typename... _Args>
721  _M_emplace(std::true_type, _Args&&... __args);
722 
723  template<typename... _Args>
724  iterator
725  _M_emplace(std::false_type __uk, _Args&&... __args)
726  { return _M_emplace(cend(), __uk, std::forward<_Args>(__args)...); }
727 
728  // Emplace with hint, useless when keys are unique.
729  template<typename... _Args>
730  iterator
731  _M_emplace(const_iterator, std::true_type __uk, _Args&&... __args)
732  { return _M_emplace(__uk, std::forward<_Args>(__args)...).first; }
733 
734  template<typename... _Args>
735  iterator
736  _M_emplace(const_iterator, std::false_type, _Args&&... __args);
737 
738  template<typename _Arg, typename _NodeGenerator>
740  _M_insert(_Arg&&, const _NodeGenerator&, true_type, size_type = 1);
741 
742  template<typename _Arg, typename _NodeGenerator>
743  iterator
744  _M_insert(_Arg&& __arg, const _NodeGenerator& __node_gen,
745  false_type __uk)
746  {
747  return _M_insert(cend(), std::forward<_Arg>(__arg), __node_gen,
748  __uk);
749  }
750 
751  // Insert with hint, not used when keys are unique.
752  template<typename _Arg, typename _NodeGenerator>
753  iterator
754  _M_insert(const_iterator, _Arg&& __arg,
755  const _NodeGenerator& __node_gen, true_type __uk)
756  {
757  return
758  _M_insert(std::forward<_Arg>(__arg), __node_gen, __uk).first;
759  }
760 
761  // Insert with hint when keys are not unique.
762  template<typename _Arg, typename _NodeGenerator>
763  iterator
764  _M_insert(const_iterator, _Arg&&,
765  const _NodeGenerator&, false_type);
766 
767  size_type
768  _M_erase(std::true_type, const key_type&);
769 
770  size_type
771  _M_erase(std::false_type, const key_type&);
772 
773  iterator
774  _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n);
775 
776  public:
777  // Emplace
778  template<typename... _Args>
779  __ireturn_type
780  emplace(_Args&&... __args)
781  { return _M_emplace(__unique_keys(), std::forward<_Args>(__args)...); }
782 
783  template<typename... _Args>
784  iterator
785  emplace_hint(const_iterator __hint, _Args&&... __args)
786  {
787  return _M_emplace(__hint, __unique_keys(),
788  std::forward<_Args>(__args)...);
789  }
790 
791  // Insert member functions via inheritance.
792 
793  // Erase
794  iterator
795  erase(const_iterator);
796 
797  // LWG 2059.
798  iterator
799  erase(iterator __it)
800  { return erase(const_iterator(__it)); }
801 
802  size_type
803  erase(const key_type& __k)
804  { return _M_erase(__unique_keys(), __k); }
805 
806  iterator
807  erase(const_iterator, const_iterator);
808 
809  void
810  clear() noexcept;
811 
812  // Set number of buckets to be appropriate for container of n element.
813  void rehash(size_type __n);
814 
815  // DR 1189.
816  // reserve, if present, comes from _Rehash_base.
817 
818 #if __cplusplus > 201402L
819  /// Re-insert an extracted node into a container with unique keys.
820  insert_return_type
821  _M_reinsert_node(node_type&& __nh)
822  {
823  insert_return_type __ret;
824  if (__nh.empty())
825  __ret.position = end();
826  else
827  {
828  __glibcxx_assert(get_allocator() == __nh.get_allocator());
829 
830  const key_type& __k = __nh._M_key();
831  __hash_code __code = this->_M_hash_code(__k);
832  size_type __bkt = _M_bucket_index(__k, __code);
833  if (__node_type* __n = _M_find_node(__bkt, __k, __code))
834  {
835  __ret.node = std::move(__nh);
836  __ret.position = iterator(__n);
837  __ret.inserted = false;
838  }
839  else
840  {
841  __ret.position
842  = _M_insert_unique_node(__bkt, __code, __nh._M_ptr);
843  __nh._M_ptr = nullptr;
844  __ret.inserted = true;
845  }
846  }
847  return __ret;
848  }
849 
850  /// Re-insert an extracted node into a container with equivalent keys.
851  iterator
852  _M_reinsert_node_multi(const_iterator __hint, node_type&& __nh)
853  {
854  iterator __ret;
855  if (__nh.empty())
856  __ret = end();
857  else
858  {
859  __glibcxx_assert(get_allocator() == __nh.get_allocator());
860 
861  auto __code = this->_M_hash_code(__nh._M_key());
862  auto __node = std::exchange(__nh._M_ptr, nullptr);
863  // FIXME: this deallocates the node on exception.
864  __ret = _M_insert_multi_node(__hint._M_cur, __code, __node);
865  }
866  return __ret;
867  }
868 
869  /// Extract a node.
870  node_type
871  extract(const_iterator __pos)
872  {
873  __node_type* __n = __pos._M_cur;
874  size_t __bkt = _M_bucket_index(__n);
875 
876  // Look for previous node to unlink it from the erased one, this
877  // is why we need buckets to contain the before begin to make
878  // this search fast.
879  __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
880 
881  if (__prev_n == _M_buckets[__bkt])
882  _M_remove_bucket_begin(__bkt, __n->_M_next(),
883  __n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
884  else if (__n->_M_nxt)
885  {
886  size_type __next_bkt = _M_bucket_index(__n->_M_next());
887  if (__next_bkt != __bkt)
888  _M_buckets[__next_bkt] = __prev_n;
889  }
890 
891  __prev_n->_M_nxt = __n->_M_nxt;
892  __n->_M_nxt = nullptr;
893  --_M_element_count;
894  return { __n, this->_M_node_allocator() };
895  }
896 
897  /// Extract a node.
898  node_type
899  extract(const _Key& __k)
900  {
901  node_type __nh;
902  auto __pos = find(__k);
903  if (__pos != end())
904  __nh = extract(const_iterator(__pos));
905  return __nh;
906  }
907 
908  /// Merge from a compatible container into one with unique keys.
909  template<typename _Compatible_Hashtable>
910  void
911  _M_merge_unique(_Compatible_Hashtable& __src) noexcept
912  {
913  static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
914  node_type>, "Node types are compatible");
915  __glibcxx_assert(get_allocator() == __src.get_allocator());
916 
917  auto __n_elt = __src.size();
918  for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
919  {
920  auto __pos = __i++;
921  const key_type& __k = this->_M_extract()(__pos._M_cur->_M_v());
922  __hash_code __code = this->_M_hash_code(__k);
923  size_type __bkt = _M_bucket_index(__k, __code);
924  if (_M_find_node(__bkt, __k, __code) == nullptr)
925  {
926  auto __nh = __src.extract(__pos);
927  _M_insert_unique_node(__bkt, __code, __nh._M_ptr, __n_elt);
928  __nh._M_ptr = nullptr;
929  __n_elt = 1;
930  }
931  else if (__n_elt != 1)
932  --__n_elt;
933  }
934  }
935 
936  /// Merge from a compatible container into one with equivalent keys.
937  template<typename _Compatible_Hashtable>
938  void
939  _M_merge_multi(_Compatible_Hashtable& __src) noexcept
940  {
941  static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
942  node_type>, "Node types are compatible");
943  __glibcxx_assert(get_allocator() == __src.get_allocator());
944 
945  this->reserve(size() + __src.size());
946  for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
947  _M_reinsert_node_multi(cend(), __src.extract(__i++));
948  }
949 #endif // C++17
950 
951  private:
952  // Helper rehash method used when keys are unique.
953  void _M_rehash_aux(size_type __n, std::true_type);
954 
955  // Helper rehash method used when keys can be non-unique.
956  void _M_rehash_aux(size_type __n, std::false_type);
957 
958  // Unconditionally change size of bucket array to n, restore
959  // hash policy state to __state on exception.
960  void _M_rehash(size_type __n, const __rehash_state& __state);
961  };
962 
963 
964  // Definitions of class template _Hashtable's out-of-line member functions.
965  template<typename _Key, typename _Value,
966  typename _Alloc, typename _ExtractKey, typename _Equal,
967  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
968  typename _Traits>
969  auto
970  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
971  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
972  _M_bucket_begin(size_type __bkt) const
973  -> __node_type*
974  {
975  __node_base* __n = _M_buckets[__bkt];
976  return __n ? static_cast<__node_type*>(__n->_M_nxt) : nullptr;
977  }
978 
979  template<typename _Key, typename _Value,
980  typename _Alloc, typename _ExtractKey, typename _Equal,
981  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
982  typename _Traits>
983  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
984  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
985  _Hashtable(size_type __bucket_hint,
986  const _H1& __h1, const _H2& __h2, const _Hash& __h,
987  const _Equal& __eq, const _ExtractKey& __exk,
988  const allocator_type& __a)
989  : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
990  {
991  auto __bkt = _M_rehash_policy._M_next_bkt(__bucket_hint);
992  if (__bkt > _M_bucket_count)
993  {
994  _M_buckets = _M_allocate_buckets(__bkt);
995  _M_bucket_count = __bkt;
996  }
997  }
998 
999  template<typename _Key, typename _Value,
1000  typename _Alloc, typename _ExtractKey, typename _Equal,
1001  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1002  typename _Traits>
1003  template<typename _InputIterator>
1004  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1005  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1006  _Hashtable(_InputIterator __f, _InputIterator __l,
1007  size_type __bucket_hint,
1008  const _H1& __h1, const _H2& __h2, const _Hash& __h,
1009  const _Equal& __eq, const _ExtractKey& __exk,
1010  const allocator_type& __a)
1011  : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
1012  {
1013  auto __nb_elems = __detail::__distance_fw(__f, __l);
1014  auto __bkt_count =
1015  _M_rehash_policy._M_next_bkt(
1016  std::max(_M_rehash_policy._M_bkt_for_elements(__nb_elems),
1017  __bucket_hint));
1018 
1019  if (__bkt_count > _M_bucket_count)
1020  {
1021  _M_buckets = _M_allocate_buckets(__bkt_count);
1022  _M_bucket_count = __bkt_count;
1023  }
1024 
1025  for (; __f != __l; ++__f)
1026  this->insert(*__f);
1027  }
1028 
1029  template<typename _Key, typename _Value,
1030  typename _Alloc, typename _ExtractKey, typename _Equal,
1031  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1032  typename _Traits>
1033  auto
1034  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1035  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1036  operator=(const _Hashtable& __ht)
1037  -> _Hashtable&
1038  {
1039  if (&__ht == this)
1040  return *this;
1041 
1042  if (__node_alloc_traits::_S_propagate_on_copy_assign())
1043  {
1044  auto& __this_alloc = this->_M_node_allocator();
1045  auto& __that_alloc = __ht._M_node_allocator();
1046  if (!__node_alloc_traits::_S_always_equal()
1047  && __this_alloc != __that_alloc)
1048  {
1049  // Replacement allocator cannot free existing storage.
1050  this->_M_deallocate_nodes(_M_begin());
1051  _M_before_begin._M_nxt = nullptr;
1052  _M_deallocate_buckets();
1053  _M_buckets = nullptr;
1054  std::__alloc_on_copy(__this_alloc, __that_alloc);
1055  __hashtable_base::operator=(__ht);
1056  _M_bucket_count = __ht._M_bucket_count;
1057  _M_element_count = __ht._M_element_count;
1058  _M_rehash_policy = __ht._M_rehash_policy;
1059  __try
1060  {
1061  _M_assign(__ht,
1062  [this](const __node_type* __n)
1063  { return this->_M_allocate_node(__n->_M_v()); });
1064  }
1065  __catch(...)
1066  {
1067  // _M_assign took care of deallocating all memory. Now we
1068  // must make sure this instance remains in a usable state.
1069  _M_reset();
1070  __throw_exception_again;
1071  }
1072  return *this;
1073  }
1074  std::__alloc_on_copy(__this_alloc, __that_alloc);
1075  }
1076 
1077  // Reuse allocated buckets and nodes.
1078  _M_assign_elements(__ht,
1079  [](const __reuse_or_alloc_node_type& __roan, const __node_type* __n)
1080  { return __roan(__n->_M_v()); });
1081  return *this;
1082  }
1083 
1084  template<typename _Key, typename _Value,
1085  typename _Alloc, typename _ExtractKey, typename _Equal,
1086  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1087  typename _Traits>
1088  template<typename _Ht, typename _NodeGenerator>
1089  void
1090  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1091  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1092  _M_assign_elements(_Ht&& __ht, const _NodeGenerator& __node_gen)
1093  {
1094  __bucket_type* __former_buckets = nullptr;
1095  std::size_t __former_bucket_count = _M_bucket_count;
1096  const __rehash_state& __former_state = _M_rehash_policy._M_state();
1097 
1098  if (_M_bucket_count != __ht._M_bucket_count)
1099  {
1100  __former_buckets = _M_buckets;
1101  _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
1102  _M_bucket_count = __ht._M_bucket_count;
1103  }
1104  else
1105  __builtin_memset(_M_buckets, 0,
1106  _M_bucket_count * sizeof(__bucket_type));
1107 
1108  __try
1109  {
1110  __hashtable_base::operator=(std::forward<_Ht>(__ht));
1111  _M_element_count = __ht._M_element_count;
1112  _M_rehash_policy = __ht._M_rehash_policy;
1113  __reuse_or_alloc_node_type __roan(_M_begin(), *this);
1114  _M_before_begin._M_nxt = nullptr;
1115  _M_assign(__ht,
1116  [&__node_gen, &__roan](__node_type* __n)
1117  { return __node_gen(__roan, __n); });
1118  if (__former_buckets)
1119  _M_deallocate_buckets(__former_buckets, __former_bucket_count);
1120  }
1121  __catch(...)
1122  {
1123  if (__former_buckets)
1124  {
1125  // Restore previous buckets.
1126  _M_deallocate_buckets();
1127  _M_rehash_policy._M_reset(__former_state);
1128  _M_buckets = __former_buckets;
1129  _M_bucket_count = __former_bucket_count;
1130  }
1131  __builtin_memset(_M_buckets, 0,
1132  _M_bucket_count * sizeof(__bucket_type));
1133  __throw_exception_again;
1134  }
1135  }
1136 
1137  template<typename _Key, typename _Value,
1138  typename _Alloc, typename _ExtractKey, typename _Equal,
1139  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1140  typename _Traits>
1141  template<typename _NodeGenerator>
1142  void
1143  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1144  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1145  _M_assign(const _Hashtable& __ht, const _NodeGenerator& __node_gen)
1146  {
1147  __bucket_type* __buckets = nullptr;
1148  if (!_M_buckets)
1149  _M_buckets = __buckets = _M_allocate_buckets(_M_bucket_count);
1150 
1151  __try
1152  {
1153  if (!__ht._M_before_begin._M_nxt)
1154  return;
1155 
1156  // First deal with the special first node pointed to by
1157  // _M_before_begin.
1158  __node_type* __ht_n = __ht._M_begin();
1159  __node_type* __this_n = __node_gen(__ht_n);
1160  this->_M_copy_code(__this_n, __ht_n);
1161  _M_before_begin._M_nxt = __this_n;
1162  _M_buckets[_M_bucket_index(__this_n)] = &_M_before_begin;
1163 
1164  // Then deal with other nodes.
1165  __node_base* __prev_n = __this_n;
1166  for (__ht_n = __ht_n->_M_next(); __ht_n; __ht_n = __ht_n->_M_next())
1167  {
1168  __this_n = __node_gen(__ht_n);
1169  __prev_n->_M_nxt = __this_n;
1170  this->_M_copy_code(__this_n, __ht_n);
1171  size_type __bkt = _M_bucket_index(__this_n);
1172  if (!_M_buckets[__bkt])
1173  _M_buckets[__bkt] = __prev_n;
1174  __prev_n = __this_n;
1175  }
1176  }
1177  __catch(...)
1178  {
1179  clear();
1180  if (__buckets)
1181  _M_deallocate_buckets();
1182  __throw_exception_again;
1183  }
1184  }
1185 
1186  template<typename _Key, typename _Value,
1187  typename _Alloc, typename _ExtractKey, typename _Equal,
1188  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1189  typename _Traits>
1190  void
1191  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1192  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1193  _M_reset() noexcept
1194  {
1195  _M_rehash_policy._M_reset();
1196  _M_bucket_count = 1;
1197  _M_single_bucket = nullptr;
1198  _M_buckets = &_M_single_bucket;
1199  _M_before_begin._M_nxt = nullptr;
1200  _M_element_count = 0;
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::true_type)
1211  {
1212  this->_M_deallocate_nodes(_M_begin());
1213  _M_deallocate_buckets();
1214  __hashtable_base::operator=(std::move(__ht));
1215  _M_rehash_policy = __ht._M_rehash_policy;
1216  if (!__ht._M_uses_single_bucket())
1217  _M_buckets = __ht._M_buckets;
1218  else
1219  {
1220  _M_buckets = &_M_single_bucket;
1221  _M_single_bucket = __ht._M_single_bucket;
1222  }
1223  _M_bucket_count = __ht._M_bucket_count;
1224  _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
1225  _M_element_count = __ht._M_element_count;
1226  std::__alloc_on_move(this->_M_node_allocator(), __ht._M_node_allocator());
1227 
1228  // Fix buckets containing the _M_before_begin pointers that can't be
1229  // moved.
1230  if (_M_begin())
1231  _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1232  __ht._M_reset();
1233  }
1234 
1235  template<typename _Key, typename _Value,
1236  typename _Alloc, typename _ExtractKey, typename _Equal,
1237  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1238  typename _Traits>
1239  void
1240  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1241  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1242  _M_move_assign(_Hashtable&& __ht, std::false_type)
1243  {
1244  if (__ht._M_node_allocator() == this->_M_node_allocator())
1245  _M_move_assign(std::move(__ht), std::true_type());
1246  else
1247  {
1248  // Can't move memory, move elements then.
1249  _M_assign_elements(std::move(__ht),
1250  [](const __reuse_or_alloc_node_type& __roan, __node_type* __n)
1251  { return __roan(std::move_if_noexcept(__n->_M_v())); });
1252  __ht.clear();
1253  }
1254  }
1255 
1256  template<typename _Key, typename _Value,
1257  typename _Alloc, typename _ExtractKey, typename _Equal,
1258  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1259  typename _Traits>
1260  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1261  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1262  _Hashtable(const _Hashtable& __ht)
1263  : __hashtable_base(__ht),
1264  __map_base(__ht),
1265  __rehash_base(__ht),
1266  __hashtable_alloc(
1267  __node_alloc_traits::_S_select_on_copy(__ht._M_node_allocator())),
1268  _M_buckets(nullptr),
1269  _M_bucket_count(__ht._M_bucket_count),
1270  _M_element_count(__ht._M_element_count),
1271  _M_rehash_policy(__ht._M_rehash_policy)
1272  {
1273  _M_assign(__ht,
1274  [this](const __node_type* __n)
1275  { return this->_M_allocate_node(__n->_M_v()); });
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(_Hashtable&& __ht, __node_alloc_type&& __a,
1285  true_type /* alloc always equal */)
1286  noexcept(_S_nothrow_move())
1287  : __hashtable_base(__ht),
1288  __map_base(__ht),
1289  __rehash_base(__ht),
1290  __hashtable_alloc(std::move(__a)),
1291  _M_buckets(__ht._M_buckets),
1292  _M_bucket_count(__ht._M_bucket_count),
1293  _M_before_begin(__ht._M_before_begin._M_nxt),
1294  _M_element_count(__ht._M_element_count),
1295  _M_rehash_policy(__ht._M_rehash_policy)
1296  {
1297  // Update buckets if __ht is using its single bucket.
1298  if (__ht._M_uses_single_bucket())
1299  {
1300  _M_buckets = &_M_single_bucket;
1301  _M_single_bucket = __ht._M_single_bucket;
1302  }
1303 
1304  // Update, if necessary, bucket pointing to before begin that hasn't
1305  // moved.
1306  if (_M_begin())
1307  _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1308 
1309  __ht._M_reset();
1310  }
1311 
1312  template<typename _Key, typename _Value,
1313  typename _Alloc, typename _ExtractKey, typename _Equal,
1314  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1315  typename _Traits>
1316  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1317  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1318  _Hashtable(const _Hashtable& __ht, const allocator_type& __a)
1319  : __hashtable_base(__ht),
1320  __map_base(__ht),
1321  __rehash_base(__ht),
1322  __hashtable_alloc(__node_alloc_type(__a)),
1323  _M_buckets(),
1324  _M_bucket_count(__ht._M_bucket_count),
1325  _M_element_count(__ht._M_element_count),
1326  _M_rehash_policy(__ht._M_rehash_policy)
1327  {
1328  _M_assign(__ht,
1329  [this](const __node_type* __n)
1330  { return this->_M_allocate_node(__n->_M_v()); });
1331  }
1332 
1333  template<typename _Key, typename _Value,
1334  typename _Alloc, typename _ExtractKey, typename _Equal,
1335  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1336  typename _Traits>
1337  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1338  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1339  _Hashtable(_Hashtable&& __ht, __node_alloc_type&& __a,
1340  false_type /* alloc always equal */)
1341  : __hashtable_base(__ht),
1342  __map_base(__ht),
1343  __rehash_base(__ht),
1344  __hashtable_alloc(std::move(__a)),
1345  _M_buckets(nullptr),
1346  _M_bucket_count(__ht._M_bucket_count),
1347  _M_element_count(__ht._M_element_count),
1348  _M_rehash_policy(__ht._M_rehash_policy)
1349  {
1350  if (__ht._M_node_allocator() == this->_M_node_allocator())
1351  {
1352  if (__ht._M_uses_single_bucket())
1353  {
1354  _M_buckets = &_M_single_bucket;
1355  _M_single_bucket = __ht._M_single_bucket;
1356  }
1357  else
1358  _M_buckets = __ht._M_buckets;
1359 
1360  _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
1361  // Update, if necessary, bucket pointing to before begin that hasn't
1362  // moved.
1363  if (_M_begin())
1364  _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1365  __ht._M_reset();
1366  }
1367  else
1368  {
1369  _M_assign(__ht,
1370  [this](__node_type* __n)
1371  {
1372  return this->_M_allocate_node(
1373  std::move_if_noexcept(__n->_M_v()));
1374  });
1375  __ht.clear();
1376  }
1377  }
1378 
1379  template<typename _Key, typename _Value,
1380  typename _Alloc, typename _ExtractKey, typename _Equal,
1381  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1382  typename _Traits>
1383  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1384  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1385  ~_Hashtable() noexcept
1386  {
1387  clear();
1388  _M_deallocate_buckets();
1389  }
1390 
1391  template<typename _Key, typename _Value,
1392  typename _Alloc, typename _ExtractKey, typename _Equal,
1393  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1394  typename _Traits>
1395  void
1396  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1397  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1398  swap(_Hashtable& __x)
1399  noexcept(__and_<__is_nothrow_swappable<_H1>,
1400  __is_nothrow_swappable<_Equal>>::value)
1401  {
1402  // The only base class with member variables is hash_code_base.
1403  // We define _Hash_code_base::_M_swap because different
1404  // specializations have different members.
1405  this->_M_swap(__x);
1406 
1407  std::__alloc_on_swap(this->_M_node_allocator(), __x._M_node_allocator());
1408  std::swap(_M_rehash_policy, __x._M_rehash_policy);
1409 
1410  // Deal properly with potentially moved instances.
1411  if (this->_M_uses_single_bucket())
1412  {
1413  if (!__x._M_uses_single_bucket())
1414  {
1415  _M_buckets = __x._M_buckets;
1416  __x._M_buckets = &__x._M_single_bucket;
1417  }
1418  }
1419  else if (__x._M_uses_single_bucket())
1420  {
1421  __x._M_buckets = _M_buckets;
1422  _M_buckets = &_M_single_bucket;
1423  }
1424  else
1425  std::swap(_M_buckets, __x._M_buckets);
1426 
1427  std::swap(_M_bucket_count, __x._M_bucket_count);
1428  std::swap(_M_before_begin._M_nxt, __x._M_before_begin._M_nxt);
1429  std::swap(_M_element_count, __x._M_element_count);
1430  std::swap(_M_single_bucket, __x._M_single_bucket);
1431 
1432  // Fix buckets containing the _M_before_begin pointers that can't be
1433  // swapped.
1434  if (_M_begin())
1435  _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1436 
1437  if (__x._M_begin())
1438  __x._M_buckets[__x._M_bucket_index(__x._M_begin())]
1439  = &__x._M_before_begin;
1440  }
1441 
1442  template<typename _Key, typename _Value,
1443  typename _Alloc, typename _ExtractKey, typename _Equal,
1444  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1445  typename _Traits>
1446  auto
1447  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1448  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1449  find(const key_type& __k)
1450  -> iterator
1451  {
1452  __hash_code __code = this->_M_hash_code(__k);
1453  std::size_t __n = _M_bucket_index(__k, __code);
1454  __node_type* __p = _M_find_node(__n, __k, __code);
1455  return __p ? iterator(__p) : end();
1456  }
1457 
1458  template<typename _Key, typename _Value,
1459  typename _Alloc, typename _ExtractKey, typename _Equal,
1460  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1461  typename _Traits>
1462  auto
1463  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1464  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1465  find(const key_type& __k) const
1466  -> const_iterator
1467  {
1468  __hash_code __code = this->_M_hash_code(__k);
1469  std::size_t __n = _M_bucket_index(__k, __code);
1470  __node_type* __p = _M_find_node(__n, __k, __code);
1471  return __p ? const_iterator(__p) : end();
1472  }
1473 
1474  template<typename _Key, typename _Value,
1475  typename _Alloc, typename _ExtractKey, typename _Equal,
1476  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1477  typename _Traits>
1478  auto
1479  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1480  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1481  count(const key_type& __k) const
1482  -> size_type
1483  {
1484  __hash_code __code = this->_M_hash_code(__k);
1485  std::size_t __n = _M_bucket_index(__k, __code);
1486  __node_type* __p = _M_bucket_begin(__n);
1487  if (!__p)
1488  return 0;
1489 
1490  std::size_t __result = 0;
1491  for (;; __p = __p->_M_next())
1492  {
1493  if (this->_M_equals(__k, __code, __p))
1494  ++__result;
1495  else if (__result)
1496  // All equivalent values are next to each other, if we
1497  // found a non-equivalent value after an equivalent one it
1498  // means that we won't find any new equivalent value.
1499  break;
1500  if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
1501  break;
1502  }
1503  return __result;
1504  }
1505 
1506  template<typename _Key, typename _Value,
1507  typename _Alloc, typename _ExtractKey, typename _Equal,
1508  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1509  typename _Traits>
1510  auto
1511  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1512  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1513  equal_range(const key_type& __k)
1514  -> pair<iterator, iterator>
1515  {
1516  __hash_code __code = this->_M_hash_code(__k);
1517  std::size_t __n = _M_bucket_index(__k, __code);
1518  __node_type* __p = _M_find_node(__n, __k, __code);
1519 
1520  if (__p)
1521  {
1522  __node_type* __p1 = __p->_M_next();
1523  while (__p1 && _M_bucket_index(__p1) == __n
1524  && this->_M_equals(__k, __code, __p1))
1525  __p1 = __p1->_M_next();
1526 
1527  return std::make_pair(iterator(__p), iterator(__p1));
1528  }
1529  else
1530  return std::make_pair(end(), end());
1531  }
1532 
1533  template<typename _Key, typename _Value,
1534  typename _Alloc, typename _ExtractKey, typename _Equal,
1535  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1536  typename _Traits>
1537  auto
1538  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1539  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1540  equal_range(const key_type& __k) const
1541  -> pair<const_iterator, const_iterator>
1542  {
1543  __hash_code __code = this->_M_hash_code(__k);
1544  std::size_t __n = _M_bucket_index(__k, __code);
1545  __node_type* __p = _M_find_node(__n, __k, __code);
1546 
1547  if (__p)
1548  {
1549  __node_type* __p1 = __p->_M_next();
1550  while (__p1 && _M_bucket_index(__p1) == __n
1551  && this->_M_equals(__k, __code, __p1))
1552  __p1 = __p1->_M_next();
1553 
1554  return std::make_pair(const_iterator(__p), const_iterator(__p1));
1555  }
1556  else
1557  return std::make_pair(end(), end());
1558  }
1559 
1560  // Find the node whose key compares equal to k in the bucket n.
1561  // Return nullptr if no node is found.
1562  template<typename _Key, typename _Value,
1563  typename _Alloc, typename _ExtractKey, typename _Equal,
1564  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1565  typename _Traits>
1566  auto
1567  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1568  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1569  _M_find_before_node(size_type __n, const key_type& __k,
1570  __hash_code __code) const
1571  -> __node_base*
1572  {
1573  __node_base* __prev_p = _M_buckets[__n];
1574  if (!__prev_p)
1575  return nullptr;
1576 
1577  for (__node_type* __p = static_cast<__node_type*>(__prev_p->_M_nxt);;
1578  __p = __p->_M_next())
1579  {
1580  if (this->_M_equals(__k, __code, __p))
1581  return __prev_p;
1582 
1583  if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
1584  break;
1585  __prev_p = __p;
1586  }
1587  return nullptr;
1588  }
1589 
1590  template<typename _Key, typename _Value,
1591  typename _Alloc, typename _ExtractKey, typename _Equal,
1592  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1593  typename _Traits>
1594  void
1595  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1596  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1597  _M_insert_bucket_begin(size_type __bkt, __node_type* __node)
1598  {
1599  if (_M_buckets[__bkt])
1600  {
1601  // Bucket is not empty, we just need to insert the new node
1602  // after the bucket before begin.
1603  __node->_M_nxt = _M_buckets[__bkt]->_M_nxt;
1604  _M_buckets[__bkt]->_M_nxt = __node;
1605  }
1606  else
1607  {
1608  // The bucket is empty, the new node is inserted at the
1609  // beginning of the singly-linked list and the bucket will
1610  // contain _M_before_begin pointer.
1611  __node->_M_nxt = _M_before_begin._M_nxt;
1612  _M_before_begin._M_nxt = __node;
1613  if (__node->_M_nxt)
1614  // We must update former begin bucket that is pointing to
1615  // _M_before_begin.
1616  _M_buckets[_M_bucket_index(__node->_M_next())] = __node;
1617  _M_buckets[__bkt] = &_M_before_begin;
1618  }
1619  }
1620 
1621  template<typename _Key, typename _Value,
1622  typename _Alloc, typename _ExtractKey, typename _Equal,
1623  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1624  typename _Traits>
1625  void
1626  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1627  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1628  _M_remove_bucket_begin(size_type __bkt, __node_type* __next,
1629  size_type __next_bkt)
1630  {
1631  if (!__next || __next_bkt != __bkt)
1632  {
1633  // Bucket is now empty
1634  // First update next bucket if any
1635  if (__next)
1636  _M_buckets[__next_bkt] = _M_buckets[__bkt];
1637 
1638  // Second update before begin node if necessary
1639  if (&_M_before_begin == _M_buckets[__bkt])
1640  _M_before_begin._M_nxt = __next;
1641  _M_buckets[__bkt] = nullptr;
1642  }
1643  }
1644 
1645  template<typename _Key, typename _Value,
1646  typename _Alloc, typename _ExtractKey, typename _Equal,
1647  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1648  typename _Traits>
1649  auto
1650  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1651  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1652  _M_get_previous_node(size_type __bkt, __node_base* __n)
1653  -> __node_base*
1654  {
1655  __node_base* __prev_n = _M_buckets[__bkt];
1656  while (__prev_n->_M_nxt != __n)
1657  __prev_n = __prev_n->_M_nxt;
1658  return __prev_n;
1659  }
1660 
1661  template<typename _Key, typename _Value,
1662  typename _Alloc, typename _ExtractKey, typename _Equal,
1663  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1664  typename _Traits>
1665  template<typename... _Args>
1666  auto
1667  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1668  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1669  _M_emplace(std::true_type, _Args&&... __args)
1670  -> pair<iterator, bool>
1671  {
1672  // First build the node to get access to the hash code
1673  __node_type* __node = this->_M_allocate_node(std::forward<_Args>(__args)...);
1674  const key_type& __k = this->_M_extract()(__node->_M_v());
1675  __hash_code __code;
1676  __try
1677  {
1678  __code = this->_M_hash_code(__k);
1679  }
1680  __catch(...)
1681  {
1682  this->_M_deallocate_node(__node);
1683  __throw_exception_again;
1684  }
1685 
1686  size_type __bkt = _M_bucket_index(__k, __code);
1687  if (__node_type* __p = _M_find_node(__bkt, __k, __code))
1688  {
1689  // There is already an equivalent node, no insertion
1690  this->_M_deallocate_node(__node);
1691  return std::make_pair(iterator(__p), false);
1692  }
1693 
1694  // Insert the node
1695  return std::make_pair(_M_insert_unique_node(__bkt, __code, __node),
1696  true);
1697  }
1698 
1699  template<typename _Key, typename _Value,
1700  typename _Alloc, typename _ExtractKey, typename _Equal,
1701  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1702  typename _Traits>
1703  template<typename... _Args>
1704  auto
1705  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1706  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1707  _M_emplace(const_iterator __hint, std::false_type, _Args&&... __args)
1708  -> iterator
1709  {
1710  // First build the node to get its hash code.
1711  __node_type* __node =
1712  this->_M_allocate_node(std::forward<_Args>(__args)...);
1713 
1714  __hash_code __code;
1715  __try
1716  {
1717  __code = this->_M_hash_code(this->_M_extract()(__node->_M_v()));
1718  }
1719  __catch(...)
1720  {
1721  this->_M_deallocate_node(__node);
1722  __throw_exception_again;
1723  }
1724 
1725  return _M_insert_multi_node(__hint._M_cur, __code, __node);
1726  }
1727 
1728  template<typename _Key, typename _Value,
1729  typename _Alloc, typename _ExtractKey, typename _Equal,
1730  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1731  typename _Traits>
1732  auto
1733  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1734  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1735  _M_insert_unique_node(size_type __bkt, __hash_code __code,
1736  __node_type* __node, size_type __n_elt)
1737  -> iterator
1738  {
1739  const __rehash_state& __saved_state = _M_rehash_policy._M_state();
1740  std::pair<bool, std::size_t> __do_rehash
1741  = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count,
1742  __n_elt);
1743 
1744  __try
1745  {
1746  if (__do_rehash.first)
1747  {
1748  _M_rehash(__do_rehash.second, __saved_state);
1749  __bkt = _M_bucket_index(this->_M_extract()(__node->_M_v()), __code);
1750  }
1751 
1752  this->_M_store_code(__node, __code);
1753 
1754  // Always insert at the beginning of the bucket.
1755  _M_insert_bucket_begin(__bkt, __node);
1756  ++_M_element_count;
1757  return iterator(__node);
1758  }
1759  __catch(...)
1760  {
1761  this->_M_deallocate_node(__node);
1762  __throw_exception_again;
1763  }
1764  }
1765 
1766  // Insert node, in bucket bkt if no rehash (assumes no element with its key
1767  // already present). Take ownership of the node, deallocate it on exception.
1768  template<typename _Key, typename _Value,
1769  typename _Alloc, typename _ExtractKey, typename _Equal,
1770  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1771  typename _Traits>
1772  auto
1773  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1774  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1775  _M_insert_multi_node(__node_type* __hint, __hash_code __code,
1776  __node_type* __node)
1777  -> iterator
1778  {
1779  const __rehash_state& __saved_state = _M_rehash_policy._M_state();
1780  std::pair<bool, std::size_t> __do_rehash
1781  = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count, 1);
1782 
1783  __try
1784  {
1785  if (__do_rehash.first)
1786  _M_rehash(__do_rehash.second, __saved_state);
1787 
1788  this->_M_store_code(__node, __code);
1789  const key_type& __k = this->_M_extract()(__node->_M_v());
1790  size_type __bkt = _M_bucket_index(__k, __code);
1791 
1792  // Find the node before an equivalent one or use hint if it exists and
1793  // if it is equivalent.
1794  __node_base* __prev
1795  = __builtin_expect(__hint != nullptr, false)
1796  && this->_M_equals(__k, __code, __hint)
1797  ? __hint
1798  : _M_find_before_node(__bkt, __k, __code);
1799  if (__prev)
1800  {
1801  // Insert after the node before the equivalent one.
1802  __node->_M_nxt = __prev->_M_nxt;
1803  __prev->_M_nxt = __node;
1804  if (__builtin_expect(__prev == __hint, false))
1805  // hint might be the last bucket node, in this case we need to
1806  // update next bucket.
1807  if (__node->_M_nxt
1808  && !this->_M_equals(__k, __code, __node->_M_next()))
1809  {
1810  size_type __next_bkt = _M_bucket_index(__node->_M_next());
1811  if (__next_bkt != __bkt)
1812  _M_buckets[__next_bkt] = __node;
1813  }
1814  }
1815  else
1816  // The inserted node has no equivalent in the
1817  // hashtable. We must insert the new node at the
1818  // beginning of the bucket to preserve equivalent
1819  // elements' relative positions.
1820  _M_insert_bucket_begin(__bkt, __node);
1821  ++_M_element_count;
1822  return iterator(__node);
1823  }
1824  __catch(...)
1825  {
1826  this->_M_deallocate_node(__node);
1827  __throw_exception_again;
1828  }
1829  }
1830 
1831  // Insert v if no element with its key is already present.
1832  template<typename _Key, typename _Value,
1833  typename _Alloc, typename _ExtractKey, typename _Equal,
1834  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1835  typename _Traits>
1836  template<typename _Arg, typename _NodeGenerator>
1837  auto
1838  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1839  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1840  _M_insert(_Arg&& __v, const _NodeGenerator& __node_gen, true_type,
1841  size_type __n_elt)
1842  -> pair<iterator, bool>
1843  {
1844  const key_type& __k = this->_M_extract()(__v);
1845  __hash_code __code = this->_M_hash_code(__k);
1846  size_type __bkt = _M_bucket_index(__k, __code);
1847 
1848  __node_type* __n = _M_find_node(__bkt, __k, __code);
1849  if (__n)
1850  return std::make_pair(iterator(__n), false);
1851 
1852  __n = __node_gen(std::forward<_Arg>(__v));
1853  return { _M_insert_unique_node(__bkt, __code, __n, __n_elt), true };
1854  }
1855 
1856  // Insert v unconditionally.
1857  template<typename _Key, typename _Value,
1858  typename _Alloc, typename _ExtractKey, typename _Equal,
1859  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1860  typename _Traits>
1861  template<typename _Arg, typename _NodeGenerator>
1862  auto
1863  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1864  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1865  _M_insert(const_iterator __hint, _Arg&& __v,
1866  const _NodeGenerator& __node_gen, false_type)
1867  -> iterator
1868  {
1869  // First compute the hash code so that we don't do anything if it
1870  // throws.
1871  __hash_code __code = this->_M_hash_code(this->_M_extract()(__v));
1872 
1873  // Second allocate new node so that we don't rehash if it throws.
1874  __node_type* __node = __node_gen(std::forward<_Arg>(__v));
1875 
1876  return _M_insert_multi_node(__hint._M_cur, __code, __node);
1877  }
1878 
1879  template<typename _Key, typename _Value,
1880  typename _Alloc, typename _ExtractKey, typename _Equal,
1881  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1882  typename _Traits>
1883  auto
1884  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1885  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1886  erase(const_iterator __it)
1887  -> iterator
1888  {
1889  __node_type* __n = __it._M_cur;
1890  std::size_t __bkt = _M_bucket_index(__n);
1891 
1892  // Look for previous node to unlink it from the erased one, this
1893  // is why we need buckets to contain the before begin to make
1894  // this search fast.
1895  __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
1896  return _M_erase(__bkt, __prev_n, __n);
1897  }
1898 
1899  template<typename _Key, typename _Value,
1900  typename _Alloc, typename _ExtractKey, typename _Equal,
1901  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1902  typename _Traits>
1903  auto
1904  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1905  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1906  _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n)
1907  -> iterator
1908  {
1909  if (__prev_n == _M_buckets[__bkt])
1910  _M_remove_bucket_begin(__bkt, __n->_M_next(),
1911  __n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
1912  else if (__n->_M_nxt)
1913  {
1914  size_type __next_bkt = _M_bucket_index(__n->_M_next());
1915  if (__next_bkt != __bkt)
1916  _M_buckets[__next_bkt] = __prev_n;
1917  }
1918 
1919  __prev_n->_M_nxt = __n->_M_nxt;
1920  iterator __result(__n->_M_next());
1921  this->_M_deallocate_node(__n);
1922  --_M_element_count;
1923 
1924  return __result;
1925  }
1926 
1927  template<typename _Key, typename _Value,
1928  typename _Alloc, typename _ExtractKey, typename _Equal,
1929  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1930  typename _Traits>
1931  auto
1932  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1933  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1934  _M_erase(std::true_type, const key_type& __k)
1935  -> size_type
1936  {
1937  __hash_code __code = this->_M_hash_code(__k);
1938  std::size_t __bkt = _M_bucket_index(__k, __code);
1939 
1940  // Look for the node before the first matching node.
1941  __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
1942  if (!__prev_n)
1943  return 0;
1944 
1945  // We found a matching node, erase it.
1946  __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
1947  _M_erase(__bkt, __prev_n, __n);
1948  return 1;
1949  }
1950 
1951  template<typename _Key, typename _Value,
1952  typename _Alloc, typename _ExtractKey, typename _Equal,
1953  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1954  typename _Traits>
1955  auto
1956  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1957  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1958  _M_erase(std::false_type, const key_type& __k)
1959  -> size_type
1960  {
1961  __hash_code __code = this->_M_hash_code(__k);
1962  std::size_t __bkt = _M_bucket_index(__k, __code);
1963 
1964  // Look for the node before the first matching node.
1965  __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
1966  if (!__prev_n)
1967  return 0;
1968 
1969  // _GLIBCXX_RESOLVE_LIB_DEFECTS
1970  // 526. Is it undefined if a function in the standard changes
1971  // in parameters?
1972  // We use one loop to find all matching nodes and another to deallocate
1973  // them so that the key stays valid during the first loop. It might be
1974  // invalidated indirectly when destroying nodes.
1975  __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
1976  __node_type* __n_last = __n;
1977  std::size_t __n_last_bkt = __bkt;
1978  do
1979  {
1980  __n_last = __n_last->_M_next();
1981  if (!__n_last)
1982  break;
1983  __n_last_bkt = _M_bucket_index(__n_last);
1984  }
1985  while (__n_last_bkt == __bkt && this->_M_equals(__k, __code, __n_last));
1986 
1987  // Deallocate nodes.
1988  size_type __result = 0;
1989  do
1990  {
1991  __node_type* __p = __n->_M_next();
1992  this->_M_deallocate_node(__n);
1993  __n = __p;
1994  ++__result;
1995  --_M_element_count;
1996  }
1997  while (__n != __n_last);
1998 
1999  if (__prev_n == _M_buckets[__bkt])
2000  _M_remove_bucket_begin(__bkt, __n_last, __n_last_bkt);
2001  else if (__n_last && __n_last_bkt != __bkt)
2002  _M_buckets[__n_last_bkt] = __prev_n;
2003  __prev_n->_M_nxt = __n_last;
2004  return __result;
2005  }
2006 
2007  template<typename _Key, typename _Value,
2008  typename _Alloc, typename _ExtractKey, typename _Equal,
2009  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2010  typename _Traits>
2011  auto
2012  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2013  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2014  erase(const_iterator __first, const_iterator __last)
2015  -> iterator
2016  {
2017  __node_type* __n = __first._M_cur;
2018  __node_type* __last_n = __last._M_cur;
2019  if (__n == __last_n)
2020  return iterator(__n);
2021 
2022  std::size_t __bkt = _M_bucket_index(__n);
2023 
2024  __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
2025  bool __is_bucket_begin = __n == _M_bucket_begin(__bkt);
2026  std::size_t __n_bkt = __bkt;
2027  for (;;)
2028  {
2029  do
2030  {
2031  __node_type* __tmp = __n;
2032  __n = __n->_M_next();
2033  this->_M_deallocate_node(__tmp);
2034  --_M_element_count;
2035  if (!__n)
2036  break;
2037  __n_bkt = _M_bucket_index(__n);
2038  }
2039  while (__n != __last_n && __n_bkt == __bkt);
2040  if (__is_bucket_begin)
2041  _M_remove_bucket_begin(__bkt, __n, __n_bkt);
2042  if (__n == __last_n)
2043  break;
2044  __is_bucket_begin = true;
2045  __bkt = __n_bkt;
2046  }
2047 
2048  if (__n && (__n_bkt != __bkt || __is_bucket_begin))
2049  _M_buckets[__n_bkt] = __prev_n;
2050  __prev_n->_M_nxt = __n;
2051  return iterator(__n);
2052  }
2053 
2054  template<typename _Key, typename _Value,
2055  typename _Alloc, typename _ExtractKey, typename _Equal,
2056  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2057  typename _Traits>
2058  void
2059  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2060  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2061  clear() noexcept
2062  {
2063  this->_M_deallocate_nodes(_M_begin());
2064  __builtin_memset(_M_buckets, 0, _M_bucket_count * sizeof(__bucket_type));
2065  _M_element_count = 0;
2066  _M_before_begin._M_nxt = nullptr;
2067  }
2068 
2069  template<typename _Key, typename _Value,
2070  typename _Alloc, typename _ExtractKey, typename _Equal,
2071  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2072  typename _Traits>
2073  void
2074  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2075  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2076  rehash(size_type __n)
2077  {
2078  const __rehash_state& __saved_state = _M_rehash_policy._M_state();
2079  std::size_t __buckets
2080  = std::max(_M_rehash_policy._M_bkt_for_elements(_M_element_count + 1),
2081  __n);
2082  __buckets = _M_rehash_policy._M_next_bkt(__buckets);
2083 
2084  if (__buckets != _M_bucket_count)
2085  _M_rehash(__buckets, __saved_state);
2086  else
2087  // No rehash, restore previous state to keep a consistent state.
2088  _M_rehash_policy._M_reset(__saved_state);
2089  }
2090 
2091  template<typename _Key, typename _Value,
2092  typename _Alloc, typename _ExtractKey, typename _Equal,
2093  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2094  typename _Traits>
2095  void
2096  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2097  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2098  _M_rehash(size_type __n, const __rehash_state& __state)
2099  {
2100  __try
2101  {
2102  _M_rehash_aux(__n, __unique_keys());
2103  }
2104  __catch(...)
2105  {
2106  // A failure here means that buckets allocation failed. We only
2107  // have to restore hash policy previous state.
2108  _M_rehash_policy._M_reset(__state);
2109  __throw_exception_again;
2110  }
2111  }
2112 
2113  // Rehash when there is no equivalent elements.
2114  template<typename _Key, typename _Value,
2115  typename _Alloc, typename _ExtractKey, typename _Equal,
2116  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2117  typename _Traits>
2118  void
2119  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2120  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2121  _M_rehash_aux(size_type __n, std::true_type)
2122  {
2123  __bucket_type* __new_buckets = _M_allocate_buckets(__n);
2124  __node_type* __p = _M_begin();
2125  _M_before_begin._M_nxt = nullptr;
2126  std::size_t __bbegin_bkt = 0;
2127  while (__p)
2128  {
2129  __node_type* __next = __p->_M_next();
2130  std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
2131  if (!__new_buckets[__bkt])
2132  {
2133  __p->_M_nxt = _M_before_begin._M_nxt;
2134  _M_before_begin._M_nxt = __p;
2135  __new_buckets[__bkt] = &_M_before_begin;
2136  if (__p->_M_nxt)
2137  __new_buckets[__bbegin_bkt] = __p;
2138  __bbegin_bkt = __bkt;
2139  }
2140  else
2141  {
2142  __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2143  __new_buckets[__bkt]->_M_nxt = __p;
2144  }
2145  __p = __next;
2146  }
2147 
2148  _M_deallocate_buckets();
2149  _M_bucket_count = __n;
2150  _M_buckets = __new_buckets;
2151  }
2152 
2153  // Rehash when there can be equivalent elements, preserve their relative
2154  // order.
2155  template<typename _Key, typename _Value,
2156  typename _Alloc, typename _ExtractKey, typename _Equal,
2157  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2158  typename _Traits>
2159  void
2160  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2161  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2162  _M_rehash_aux(size_type __n, std::false_type)
2163  {
2164  __bucket_type* __new_buckets = _M_allocate_buckets(__n);
2165 
2166  __node_type* __p = _M_begin();
2167  _M_before_begin._M_nxt = nullptr;
2168  std::size_t __bbegin_bkt = 0;
2169  std::size_t __prev_bkt = 0;
2170  __node_type* __prev_p = nullptr;
2171  bool __check_bucket = false;
2172 
2173  while (__p)
2174  {
2175  __node_type* __next = __p->_M_next();
2176  std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
2177 
2178  if (__prev_p && __prev_bkt == __bkt)
2179  {
2180  // Previous insert was already in this bucket, we insert after
2181  // the previously inserted one to preserve equivalent elements
2182  // relative order.
2183  __p->_M_nxt = __prev_p->_M_nxt;
2184  __prev_p->_M_nxt = __p;
2185 
2186  // Inserting after a node in a bucket require to check that we
2187  // haven't change the bucket last node, in this case next
2188  // bucket containing its before begin node must be updated. We
2189  // schedule a check as soon as we move out of the sequence of
2190  // equivalent nodes to limit the number of checks.
2191  __check_bucket = true;
2192  }
2193  else
2194  {
2195  if (__check_bucket)
2196  {
2197  // Check if we shall update the next bucket because of
2198  // insertions into __prev_bkt bucket.
2199  if (__prev_p->_M_nxt)
2200  {
2201  std::size_t __next_bkt
2202  = __hash_code_base::_M_bucket_index(__prev_p->_M_next(),
2203  __n);
2204  if (__next_bkt != __prev_bkt)
2205  __new_buckets[__next_bkt] = __prev_p;
2206  }
2207  __check_bucket = false;
2208  }
2209 
2210  if (!__new_buckets[__bkt])
2211  {
2212  __p->_M_nxt = _M_before_begin._M_nxt;
2213  _M_before_begin._M_nxt = __p;
2214  __new_buckets[__bkt] = &_M_before_begin;
2215  if (__p->_M_nxt)
2216  __new_buckets[__bbegin_bkt] = __p;
2217  __bbegin_bkt = __bkt;
2218  }
2219  else
2220  {
2221  __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2222  __new_buckets[__bkt]->_M_nxt = __p;
2223  }
2224  }
2225  __prev_p = __p;
2226  __prev_bkt = __bkt;
2227  __p = __next;
2228  }
2229 
2230  if (__check_bucket && __prev_p->_M_nxt)
2231  {
2232  std::size_t __next_bkt
2233  = __hash_code_base::_M_bucket_index(__prev_p->_M_next(), __n);
2234  if (__next_bkt != __prev_bkt)
2235  __new_buckets[__next_bkt] = __prev_p;
2236  }
2237 
2238  _M_deallocate_buckets();
2239  _M_bucket_count = __n;
2240  _M_buckets = __new_buckets;
2241  }
2242 
2243 #if __cplusplus > 201402L
2244  template<typename, typename, typename> class _Hash_merge_helper { };
2245 #endif // C++17
2246 
2247 #if __cpp_deduction_guides >= 201606
2248  // Used to constrain deduction guides
2249  template<typename _Hash>
2250  using _RequireNotAllocatorOrIntegral
2251  = __enable_if_t<!__or_<is_integral<_Hash>, __is_allocator<_Hash>>::value>;
2252 #endif
2253 
2254 _GLIBCXX_END_NAMESPACE_VERSION
2255 } // namespace std
2256 
2257 #endif // _HASHTABLE_H
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition: type_traits:75
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
Definition: type_traits:78
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
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
_GLIBCXX14_CONSTEXPR const _Tp & max(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:222
ISO C++ entities toplevel namespace is std.
_Tp exchange(_Tp &__obj, _Up &&__new_val)
Assign __new_val to __obj and return its previous value.
Definition: utility:286
constexpr const _Tp * begin(initializer_list< _Tp > __ils) noexcept
Return an iterator pointing to the first element of the initializer_list.
constexpr const _Tp * end(initializer_list< _Tp > __ils) noexcept
Return an iterator pointing to one past the last element of the initializer_list.
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
_GLIBCXX17_CONSTEXPR iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
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
integral_constant
Definition: type_traits:58
Define a member typedef type to one of two argument types.
Definition: type_traits:2054
is_default_constructible
Definition: type_traits:891
is_nothrow_copy_constructible
Definition: type_traits:988
is_nothrow_move_assignable
Definition: type_traits:1096
is_same
Definition: type_traits:1286
Node iterators, used to iterate through all the hashtable.
Node const_iterators, used to iterate through all the hashtable.
Struct holding two objects of arbitrary type.
Definition: stl_pair.h:210
_T1 first
second_type is the second bound type
Definition: stl_pair.h:214
_T2 second
first is a copy of the first object
Definition: stl_pair.h:215
Uniform interface to C++98 and C++11 allocators.