libstdc++
bits/hashtable.h
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1 // hashtable.h header -*- C++ -*-
2 
3 // Copyright (C) 2007-2017 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  __detail::__is_noexcept_hash<_Tp, _Hash>>>;
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  using __traits_type = _Traits;
190  using __hash_cached = typename __traits_type::__hash_cached;
192  using __node_alloc_type = __alloc_rebind<_Alloc, __node_type>;
193 
195 
196  using __value_alloc_traits =
198  using __node_alloc_traits =
200  using __node_base = typename __hashtable_alloc::__node_base;
201  using __bucket_type = typename __hashtable_alloc::__bucket_type;
202 
203  public:
204  typedef _Key key_type;
205  typedef _Value value_type;
206  typedef _Alloc allocator_type;
207  typedef _Equal key_equal;
208 
209  // mapped_type, if present, comes from _Map_base.
210  // hasher, if present, comes from _Hash_code_base/_Hashtable_base.
211  typedef typename __value_alloc_traits::pointer pointer;
212  typedef typename __value_alloc_traits::const_pointer const_pointer;
213  typedef value_type& reference;
214  typedef const value_type& const_reference;
215 
216  private:
217  using __rehash_type = _RehashPolicy;
218  using __rehash_state = typename __rehash_type::_State;
219 
220  using __constant_iterators = typename __traits_type::__constant_iterators;
221  using __unique_keys = typename __traits_type::__unique_keys;
222 
223  using __key_extract = typename std::conditional<
224  __constant_iterators::value,
225  __detail::_Identity,
226  __detail::_Select1st>::type;
227 
228  using __hashtable_base = __detail::
229  _Hashtable_base<_Key, _Value, _ExtractKey,
230  _Equal, _H1, _H2, _Hash, _Traits>;
231 
232  using __hash_code_base = typename __hashtable_base::__hash_code_base;
233  using __hash_code = typename __hashtable_base::__hash_code;
234  using __ireturn_type = typename __hashtable_base::__ireturn_type;
235 
236  using __map_base = __detail::_Map_base<_Key, _Value, _Alloc, _ExtractKey,
237  _Equal, _H1, _H2, _Hash,
238  _RehashPolicy, _Traits>;
239 
240  using __rehash_base = __detail::_Rehash_base<_Key, _Value, _Alloc,
241  _ExtractKey, _Equal,
242  _H1, _H2, _Hash,
243  _RehashPolicy, _Traits>;
244 
245  using __eq_base = __detail::_Equality<_Key, _Value, _Alloc, _ExtractKey,
246  _Equal, _H1, _H2, _Hash,
247  _RehashPolicy, _Traits>;
248 
249  using __reuse_or_alloc_node_type =
250  __detail::_ReuseOrAllocNode<__node_alloc_type>;
251 
252  // Metaprogramming for picking apart hash caching.
253  template<typename _Cond>
254  using __if_hash_cached = __or_<__not_<__hash_cached>, _Cond>;
255 
256  template<typename _Cond>
257  using __if_hash_not_cached = __or_<__hash_cached, _Cond>;
258 
259  // Compile-time diagnostics.
260 
261  // _Hash_code_base has everything protected, so use this derived type to
262  // access it.
263  struct __hash_code_base_access : __hash_code_base
264  { using __hash_code_base::_M_bucket_index; };
265 
266  // Getting a bucket index from a node shall not throw because it is used
267  // in methods (erase, swap...) that shall not throw.
268  static_assert(noexcept(declval<const __hash_code_base_access&>()
269  ._M_bucket_index((const __node_type*)nullptr,
270  (std::size_t)0)),
271  "Cache the hash code or qualify your functors involved"
272  " in hash code and bucket index computation with noexcept");
273 
274  // Following two static assertions are necessary to guarantee
275  // that local_iterator will be default constructible.
276 
277  // When hash codes are cached local iterator inherits from H2 functor
278  // which must then be default constructible.
279  static_assert(__if_hash_cached<is_default_constructible<_H2>>::value,
280  "Functor used to map hash code to bucket index"
281  " must be default constructible");
282 
283  template<typename _Keya, typename _Valuea, typename _Alloca,
284  typename _ExtractKeya, typename _Equala,
285  typename _H1a, typename _H2a, typename _Hasha,
286  typename _RehashPolicya, typename _Traitsa,
287  bool _Unique_keysa>
288  friend struct __detail::_Map_base;
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  friend struct __detail::_Insert_base;
295 
296  template<typename _Keya, typename _Valuea, typename _Alloca,
297  typename _ExtractKeya, typename _Equala,
298  typename _H1a, typename _H2a, typename _Hasha,
299  typename _RehashPolicya, typename _Traitsa,
300  bool _Constant_iteratorsa>
301  friend struct __detail::_Insert;
302 
303  public:
304  using size_type = typename __hashtable_base::size_type;
305  using difference_type = typename __hashtable_base::difference_type;
306 
307  using iterator = typename __hashtable_base::iterator;
308  using const_iterator = typename __hashtable_base::const_iterator;
309 
310  using local_iterator = typename __hashtable_base::local_iterator;
311  using const_local_iterator = typename __hashtable_base::
312  const_local_iterator;
313 
314 #if __cplusplus > 201402L
315  using node_type = _Node_handle<_Key, _Value, __node_alloc_type>;
316  using insert_return_type = _Node_insert_return<iterator, node_type>;
317 #endif
318 
319  private:
320  __bucket_type* _M_buckets = &_M_single_bucket;
321  size_type _M_bucket_count = 1;
322  __node_base _M_before_begin;
323  size_type _M_element_count = 0;
324  _RehashPolicy _M_rehash_policy;
325 
326  // A single bucket used when only need for 1 bucket. Especially
327  // interesting in move semantic to leave hashtable with only 1 buckets
328  // which is not allocated so that we can have those operations noexcept
329  // qualified.
330  // Note that we can't leave hashtable with 0 bucket without adding
331  // numerous checks in the code to avoid 0 modulus.
332  __bucket_type _M_single_bucket = nullptr;
333 
334  bool
335  _M_uses_single_bucket(__bucket_type* __bkts) const
336  { return __builtin_expect(__bkts == &_M_single_bucket, false); }
337 
338  bool
339  _M_uses_single_bucket() const
340  { return _M_uses_single_bucket(_M_buckets); }
341 
343  _M_base_alloc() { return *this; }
344 
345  __bucket_type*
346  _M_allocate_buckets(size_type __n)
347  {
348  if (__builtin_expect(__n == 1, false))
349  {
350  _M_single_bucket = nullptr;
351  return &_M_single_bucket;
352  }
353 
354  return __hashtable_alloc::_M_allocate_buckets(__n);
355  }
356 
357  void
358  _M_deallocate_buckets(__bucket_type* __bkts, size_type __n)
359  {
360  if (_M_uses_single_bucket(__bkts))
361  return;
362 
363  __hashtable_alloc::_M_deallocate_buckets(__bkts, __n);
364  }
365 
366  void
367  _M_deallocate_buckets()
368  { _M_deallocate_buckets(_M_buckets, _M_bucket_count); }
369 
370  // Gets bucket begin, deals with the fact that non-empty buckets contain
371  // their before begin node.
372  __node_type*
373  _M_bucket_begin(size_type __bkt) const;
374 
375  __node_type*
376  _M_begin() const
377  { return static_cast<__node_type*>(_M_before_begin._M_nxt); }
378 
379  template<typename _NodeGenerator>
380  void
381  _M_assign(const _Hashtable&, const _NodeGenerator&);
382 
383  void
384  _M_move_assign(_Hashtable&&, std::true_type);
385 
386  void
387  _M_move_assign(_Hashtable&&, std::false_type);
388 
389  void
390  _M_reset() noexcept;
391 
392  _Hashtable(const _H1& __h1, const _H2& __h2, const _Hash& __h,
393  const _Equal& __eq, const _ExtractKey& __exk,
394  const allocator_type& __a)
395  : __hashtable_base(__exk, __h1, __h2, __h, __eq),
396  __hashtable_alloc(__node_alloc_type(__a))
397  { }
398 
399  public:
400  // Constructor, destructor, assignment, swap
401  _Hashtable() = default;
402  _Hashtable(size_type __bucket_hint,
403  const _H1&, const _H2&, const _Hash&,
404  const _Equal&, const _ExtractKey&,
405  const allocator_type&);
406 
407  template<typename _InputIterator>
408  _Hashtable(_InputIterator __first, _InputIterator __last,
409  size_type __bucket_hint,
410  const _H1&, const _H2&, const _Hash&,
411  const _Equal&, const _ExtractKey&,
412  const allocator_type&);
413 
414  _Hashtable(const _Hashtable&);
415 
416  _Hashtable(_Hashtable&&) noexcept;
417 
418  _Hashtable(const _Hashtable&, const allocator_type&);
419 
420  _Hashtable(_Hashtable&&, const allocator_type&);
421 
422  // Use delegating constructors.
423  explicit
424  _Hashtable(const allocator_type& __a)
425  : __hashtable_alloc(__node_alloc_type(__a))
426  { }
427 
428  explicit
429  _Hashtable(size_type __n,
430  const _H1& __hf = _H1(),
431  const key_equal& __eql = key_equal(),
432  const allocator_type& __a = allocator_type())
433  : _Hashtable(__n, __hf, _H2(), _Hash(), __eql,
434  __key_extract(), __a)
435  { }
436 
437  template<typename _InputIterator>
438  _Hashtable(_InputIterator __f, _InputIterator __l,
439  size_type __n = 0,
440  const _H1& __hf = _H1(),
441  const key_equal& __eql = key_equal(),
442  const allocator_type& __a = allocator_type())
443  : _Hashtable(__f, __l, __n, __hf, _H2(), _Hash(), __eql,
444  __key_extract(), __a)
445  { }
446 
448  size_type __n = 0,
449  const _H1& __hf = _H1(),
450  const key_equal& __eql = key_equal(),
451  const allocator_type& __a = allocator_type())
452  : _Hashtable(__l.begin(), __l.end(), __n, __hf, _H2(), _Hash(), __eql,
453  __key_extract(), __a)
454  { }
455 
456  _Hashtable&
457  operator=(const _Hashtable& __ht);
458 
459  _Hashtable&
460  operator=(_Hashtable&& __ht)
461  noexcept(__node_alloc_traits::_S_nothrow_move()
462  && is_nothrow_move_assignable<_H1>::value
463  && is_nothrow_move_assignable<_Equal>::value)
464  {
465  constexpr bool __move_storage =
466  __node_alloc_traits::_S_propagate_on_move_assign()
467  || __node_alloc_traits::_S_always_equal();
468  _M_move_assign(std::move(__ht), __bool_constant<__move_storage>());
469  return *this;
470  }
471 
472  _Hashtable&
473  operator=(initializer_list<value_type> __l)
474  {
475  __reuse_or_alloc_node_type __roan(_M_begin(), *this);
476  _M_before_begin._M_nxt = nullptr;
477  clear();
478  this->_M_insert_range(__l.begin(), __l.end(), __roan);
479  return *this;
480  }
481 
482  ~_Hashtable() noexcept;
483 
484  void
485  swap(_Hashtable&)
486  noexcept(__and_<__is_nothrow_swappable<_H1>,
487  __is_nothrow_swappable<_Equal>>::value);
488 
489  // Basic container operations
490  iterator
491  begin() noexcept
492  { return iterator(_M_begin()); }
493 
494  const_iterator
495  begin() const noexcept
496  { return const_iterator(_M_begin()); }
497 
498  iterator
499  end() noexcept
500  { return iterator(nullptr); }
501 
502  const_iterator
503  end() const noexcept
504  { return const_iterator(nullptr); }
505 
506  const_iterator
507  cbegin() const noexcept
508  { return const_iterator(_M_begin()); }
509 
510  const_iterator
511  cend() const noexcept
512  { return const_iterator(nullptr); }
513 
514  size_type
515  size() const noexcept
516  { return _M_element_count; }
517 
518  bool
519  empty() const noexcept
520  { return size() == 0; }
521 
522  allocator_type
523  get_allocator() const noexcept
524  { return allocator_type(this->_M_node_allocator()); }
525 
526  size_type
527  max_size() const noexcept
528  { return __node_alloc_traits::max_size(this->_M_node_allocator()); }
529 
530  // Observers
531  key_equal
532  key_eq() const
533  { return this->_M_eq(); }
534 
535  // hash_function, if present, comes from _Hash_code_base.
536 
537  // Bucket operations
538  size_type
539  bucket_count() const noexcept
540  { return _M_bucket_count; }
541 
542  size_type
543  max_bucket_count() const noexcept
544  { return max_size(); }
545 
546  size_type
547  bucket_size(size_type __n) const
548  { return std::distance(begin(__n), end(__n)); }
549 
550  size_type
551  bucket(const key_type& __k) const
552  { return _M_bucket_index(__k, this->_M_hash_code(__k)); }
553 
554  local_iterator
555  begin(size_type __n)
556  {
557  return local_iterator(*this, _M_bucket_begin(__n),
558  __n, _M_bucket_count);
559  }
560 
561  local_iterator
562  end(size_type __n)
563  { return local_iterator(*this, nullptr, __n, _M_bucket_count); }
564 
565  const_local_iterator
566  begin(size_type __n) const
567  {
568  return const_local_iterator(*this, _M_bucket_begin(__n),
569  __n, _M_bucket_count);
570  }
571 
572  const_local_iterator
573  end(size_type __n) const
574  { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
575 
576  // DR 691.
577  const_local_iterator
578  cbegin(size_type __n) const
579  {
580  return const_local_iterator(*this, _M_bucket_begin(__n),
581  __n, _M_bucket_count);
582  }
583 
584  const_local_iterator
585  cend(size_type __n) const
586  { return const_local_iterator(*this, nullptr, __n, _M_bucket_count); }
587 
588  float
589  load_factor() const noexcept
590  {
591  return static_cast<float>(size()) / static_cast<float>(bucket_count());
592  }
593 
594  // max_load_factor, if present, comes from _Rehash_base.
595 
596  // Generalization of max_load_factor. Extension, not found in
597  // TR1. Only useful if _RehashPolicy is something other than
598  // the default.
599  const _RehashPolicy&
600  __rehash_policy() const
601  { return _M_rehash_policy; }
602 
603  void
604  __rehash_policy(const _RehashPolicy& __pol)
605  { _M_rehash_policy = __pol; }
606 
607  // Lookup.
608  iterator
609  find(const key_type& __k);
610 
611  const_iterator
612  find(const key_type& __k) const;
613 
614  size_type
615  count(const key_type& __k) const;
616 
618  equal_range(const key_type& __k);
619 
621  equal_range(const key_type& __k) const;
622 
623  protected:
624  // Bucket index computation helpers.
625  size_type
626  _M_bucket_index(__node_type* __n) const noexcept
627  { return __hash_code_base::_M_bucket_index(__n, _M_bucket_count); }
628 
629  size_type
630  _M_bucket_index(const key_type& __k, __hash_code __c) const
631  { return __hash_code_base::_M_bucket_index(__k, __c, _M_bucket_count); }
632 
633  // Find and insert helper functions and types
634  // Find the node before the one matching the criteria.
635  __node_base*
636  _M_find_before_node(size_type, const key_type&, __hash_code) const;
637 
638  __node_type*
639  _M_find_node(size_type __bkt, const key_type& __key,
640  __hash_code __c) const
641  {
642  __node_base* __before_n = _M_find_before_node(__bkt, __key, __c);
643  if (__before_n)
644  return static_cast<__node_type*>(__before_n->_M_nxt);
645  return nullptr;
646  }
647 
648  // Insert a node at the beginning of a bucket.
649  void
650  _M_insert_bucket_begin(size_type, __node_type*);
651 
652  // Remove the bucket first node
653  void
654  _M_remove_bucket_begin(size_type __bkt, __node_type* __next_n,
655  size_type __next_bkt);
656 
657  // Get the node before __n in the bucket __bkt
658  __node_base*
659  _M_get_previous_node(size_type __bkt, __node_base* __n);
660 
661  // Insert node with hash code __code, in bucket bkt if no rehash (assumes
662  // no element with its key already present). Take ownership of the node,
663  // deallocate it on exception.
664  iterator
665  _M_insert_unique_node(size_type __bkt, __hash_code __code,
666  __node_type* __n);
667 
668  // Insert node with hash code __code. Take ownership of the node,
669  // deallocate it on exception.
670  iterator
671  _M_insert_multi_node(__node_type* __hint,
672  __hash_code __code, __node_type* __n);
673 
674  template<typename... _Args>
676  _M_emplace(std::true_type, _Args&&... __args);
677 
678  template<typename... _Args>
679  iterator
680  _M_emplace(std::false_type __uk, _Args&&... __args)
681  { return _M_emplace(cend(), __uk, std::forward<_Args>(__args)...); }
682 
683  // Emplace with hint, useless when keys are unique.
684  template<typename... _Args>
685  iterator
686  _M_emplace(const_iterator, std::true_type __uk, _Args&&... __args)
687  { return _M_emplace(__uk, std::forward<_Args>(__args)...).first; }
688 
689  template<typename... _Args>
690  iterator
691  _M_emplace(const_iterator, std::false_type, _Args&&... __args);
692 
693  template<typename _Arg, typename _NodeGenerator>
695  _M_insert(_Arg&&, const _NodeGenerator&, std::true_type);
696 
697  template<typename _Arg, typename _NodeGenerator>
698  iterator
699  _M_insert(_Arg&& __arg, const _NodeGenerator& __node_gen,
700  std::false_type __uk)
701  {
702  return _M_insert(cend(), std::forward<_Arg>(__arg), __node_gen,
703  __uk);
704  }
705 
706  // Insert with hint, not used when keys are unique.
707  template<typename _Arg, typename _NodeGenerator>
708  iterator
709  _M_insert(const_iterator, _Arg&& __arg,
710  const _NodeGenerator& __node_gen, std::true_type __uk)
711  {
712  return
713  _M_insert(std::forward<_Arg>(__arg), __node_gen, __uk).first;
714  }
715 
716  // Insert with hint when keys are not unique.
717  template<typename _Arg, typename _NodeGenerator>
718  iterator
719  _M_insert(const_iterator, _Arg&&,
720  const _NodeGenerator&, std::false_type);
721 
722  size_type
723  _M_erase(std::true_type, const key_type&);
724 
725  size_type
726  _M_erase(std::false_type, const key_type&);
727 
728  iterator
729  _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n);
730 
731  public:
732  // Emplace
733  template<typename... _Args>
734  __ireturn_type
735  emplace(_Args&&... __args)
736  { return _M_emplace(__unique_keys(), std::forward<_Args>(__args)...); }
737 
738  template<typename... _Args>
739  iterator
740  emplace_hint(const_iterator __hint, _Args&&... __args)
741  {
742  return _M_emplace(__hint, __unique_keys(),
743  std::forward<_Args>(__args)...);
744  }
745 
746  // Insert member functions via inheritance.
747 
748  // Erase
749  iterator
750  erase(const_iterator);
751 
752  // LWG 2059.
753  iterator
754  erase(iterator __it)
755  { return erase(const_iterator(__it)); }
756 
757  size_type
758  erase(const key_type& __k)
759  { return _M_erase(__unique_keys(), __k); }
760 
761  iterator
762  erase(const_iterator, const_iterator);
763 
764  void
765  clear() noexcept;
766 
767  // Set number of buckets to be appropriate for container of n element.
768  void rehash(size_type __n);
769 
770  // DR 1189.
771  // reserve, if present, comes from _Rehash_base.
772 
773 #if __cplusplus > 201402L
774  /// Re-insert an extracted node into a container with unique keys.
775  insert_return_type
776  _M_reinsert_node(node_type&& __nh)
777  {
778  insert_return_type __ret;
779  if (__nh.empty())
780  __ret.position = end();
781  else
782  {
783  __glibcxx_assert(get_allocator() == __nh.get_allocator());
784 
785  const key_type& __k = __nh._M_key();
786  __hash_code __code = this->_M_hash_code(__k);
787  size_type __bkt = _M_bucket_index(__k, __code);
788  if (__node_type* __n = _M_find_node(__bkt, __k, __code))
789  {
790  __ret.node = std::move(__nh);
791  __ret.position = iterator(__n);
792  __ret.inserted = false;
793  }
794  else
795  {
796  __ret.position
797  = _M_insert_unique_node(__bkt, __code, __nh._M_ptr);
798  __nh._M_ptr = nullptr;
799  __ret.inserted = true;
800  }
801  }
802  return __ret;
803  }
804 
805  /// Re-insert an extracted node into a container with equivalent keys.
806  iterator
807  _M_reinsert_node_multi(const_iterator __hint, node_type&& __nh)
808  {
809  iterator __ret;
810  if (__nh.empty())
811  __ret = end();
812  else
813  {
814  __glibcxx_assert(get_allocator() == __nh.get_allocator());
815 
816  auto __code = this->_M_hash_code(__nh._M_key());
817  auto __node = std::exchange(__nh._M_ptr, nullptr);
818  // FIXME: this deallocates the node on exception.
819  __ret = _M_insert_multi_node(__hint._M_cur, __code, __node);
820  }
821  return __ret;
822  }
823 
824  /// Extract a node.
825  node_type
826  extract(const_iterator __pos)
827  {
828  __node_type* __n = __pos._M_cur;
829  size_t __bkt = _M_bucket_index(__n);
830 
831  // Look for previous node to unlink it from the erased one, this
832  // is why we need buckets to contain the before begin to make
833  // this search fast.
834  __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
835 
836  if (__prev_n == _M_buckets[__bkt])
837  _M_remove_bucket_begin(__bkt, __n->_M_next(),
838  __n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
839  else if (__n->_M_nxt)
840  {
841  size_type __next_bkt = _M_bucket_index(__n->_M_next());
842  if (__next_bkt != __bkt)
843  _M_buckets[__next_bkt] = __prev_n;
844  }
845 
846  __prev_n->_M_nxt = __n->_M_nxt;
847  __n->_M_nxt = nullptr;
848  --_M_element_count;
849  return { __n, this->_M_node_allocator() };
850  }
851 
852  /// Extract a node.
853  node_type
854  extract(const _Key& __k)
855  {
856  node_type __nh;
857  auto __pos = find(__k);
858  if (__pos != end())
859  __nh = extract(const_iterator(__pos));
860  return __nh;
861  }
862 
863  /// Merge from a compatible container into one with unique keys.
864  template<typename _Compatible_Hashtable>
865  void
866  _M_merge_unique(_Compatible_Hashtable& __src) noexcept
867  {
868  static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
869  node_type>, "Node types are compatible");
870  __glibcxx_assert(get_allocator() == __src.get_allocator());
871 
872  for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
873  {
874  auto __pos = __i++;
875  const key_type& __k = this->_M_extract()(__pos._M_cur->_M_v());
876  __hash_code __code = this->_M_hash_code(__k);
877  size_type __bkt = _M_bucket_index(__k, __code);
878  if (_M_find_node(__bkt, __k, __code) == nullptr)
879  {
880  auto __nh = __src.extract(__pos);
881  _M_insert_unique_node(__bkt, __code, __nh._M_ptr);
882  __nh._M_ptr = nullptr;
883  }
884  }
885  }
886 
887  /// Merge from a compatible container into one with equivalent keys.
888  template<typename _Compatible_Hashtable>
889  void
890  _M_merge_multi(_Compatible_Hashtable& __src) noexcept
891  {
892  static_assert(is_same_v<typename _Compatible_Hashtable::node_type,
893  node_type>, "Node types are compatible");
894  __glibcxx_assert(get_allocator() == __src.get_allocator());
895 
896  this->reserve(size() + __src.size());
897  for (auto __i = __src.begin(), __end = __src.end(); __i != __end;)
898  _M_reinsert_node_multi(cend(), __src.extract(__i++));
899  }
900 #endif // C++17
901 
902  private:
903  // Helper rehash method used when keys are unique.
904  void _M_rehash_aux(size_type __n, std::true_type);
905 
906  // Helper rehash method used when keys can be non-unique.
907  void _M_rehash_aux(size_type __n, std::false_type);
908 
909  // Unconditionally change size of bucket array to n, restore
910  // hash policy state to __state on exception.
911  void _M_rehash(size_type __n, const __rehash_state& __state);
912  };
913 
914 
915  // Definitions of class template _Hashtable's out-of-line member functions.
916  template<typename _Key, typename _Value,
917  typename _Alloc, typename _ExtractKey, typename _Equal,
918  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
919  typename _Traits>
920  auto
921  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
922  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
923  _M_bucket_begin(size_type __bkt) const
924  -> __node_type*
925  {
926  __node_base* __n = _M_buckets[__bkt];
927  return __n ? static_cast<__node_type*>(__n->_M_nxt) : nullptr;
928  }
929 
930  template<typename _Key, typename _Value,
931  typename _Alloc, typename _ExtractKey, typename _Equal,
932  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
933  typename _Traits>
934  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
935  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
936  _Hashtable(size_type __bucket_hint,
937  const _H1& __h1, const _H2& __h2, const _Hash& __h,
938  const _Equal& __eq, const _ExtractKey& __exk,
939  const allocator_type& __a)
940  : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
941  {
942  auto __bkt = _M_rehash_policy._M_next_bkt(__bucket_hint);
943  if (__bkt > _M_bucket_count)
944  {
945  _M_buckets = _M_allocate_buckets(__bkt);
946  _M_bucket_count = __bkt;
947  }
948  }
949 
950  template<typename _Key, typename _Value,
951  typename _Alloc, typename _ExtractKey, typename _Equal,
952  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
953  typename _Traits>
954  template<typename _InputIterator>
955  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
956  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
957  _Hashtable(_InputIterator __f, _InputIterator __l,
958  size_type __bucket_hint,
959  const _H1& __h1, const _H2& __h2, const _Hash& __h,
960  const _Equal& __eq, const _ExtractKey& __exk,
961  const allocator_type& __a)
962  : _Hashtable(__h1, __h2, __h, __eq, __exk, __a)
963  {
964  auto __nb_elems = __detail::__distance_fw(__f, __l);
965  auto __bkt_count =
966  _M_rehash_policy._M_next_bkt(
967  std::max(_M_rehash_policy._M_bkt_for_elements(__nb_elems),
968  __bucket_hint));
969 
970  if (__bkt_count > _M_bucket_count)
971  {
972  _M_buckets = _M_allocate_buckets(__bkt_count);
973  _M_bucket_count = __bkt_count;
974  }
975 
976  for (; __f != __l; ++__f)
977  this->insert(*__f);
978  }
979 
980  template<typename _Key, typename _Value,
981  typename _Alloc, typename _ExtractKey, typename _Equal,
982  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
983  typename _Traits>
984  auto
985  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
986  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
987  operator=(const _Hashtable& __ht)
988  -> _Hashtable&
989  {
990  if (&__ht == this)
991  return *this;
992 
993  if (__node_alloc_traits::_S_propagate_on_copy_assign())
994  {
995  auto& __this_alloc = this->_M_node_allocator();
996  auto& __that_alloc = __ht._M_node_allocator();
997  if (!__node_alloc_traits::_S_always_equal()
998  && __this_alloc != __that_alloc)
999  {
1000  // Replacement allocator cannot free existing storage.
1001  this->_M_deallocate_nodes(_M_begin());
1002  _M_before_begin._M_nxt = nullptr;
1003  _M_deallocate_buckets();
1004  _M_buckets = nullptr;
1005  std::__alloc_on_copy(__this_alloc, __that_alloc);
1006  __hashtable_base::operator=(__ht);
1007  _M_bucket_count = __ht._M_bucket_count;
1008  _M_element_count = __ht._M_element_count;
1009  _M_rehash_policy = __ht._M_rehash_policy;
1010  __try
1011  {
1012  _M_assign(__ht,
1013  [this](const __node_type* __n)
1014  { return this->_M_allocate_node(__n->_M_v()); });
1015  }
1016  __catch(...)
1017  {
1018  // _M_assign took care of deallocating all memory. Now we
1019  // must make sure this instance remains in a usable state.
1020  _M_reset();
1021  __throw_exception_again;
1022  }
1023  return *this;
1024  }
1025  std::__alloc_on_copy(__this_alloc, __that_alloc);
1026  }
1027 
1028  // Reuse allocated buckets and nodes.
1029  __bucket_type* __former_buckets = nullptr;
1030  std::size_t __former_bucket_count = _M_bucket_count;
1031  const __rehash_state& __former_state = _M_rehash_policy._M_state();
1032 
1033  if (_M_bucket_count != __ht._M_bucket_count)
1034  {
1035  __former_buckets = _M_buckets;
1036  _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
1037  _M_bucket_count = __ht._M_bucket_count;
1038  }
1039  else
1040  __builtin_memset(_M_buckets, 0,
1041  _M_bucket_count * sizeof(__bucket_type));
1042 
1043  __try
1044  {
1045  __hashtable_base::operator=(__ht);
1046  _M_element_count = __ht._M_element_count;
1047  _M_rehash_policy = __ht._M_rehash_policy;
1048  __reuse_or_alloc_node_type __roan(_M_begin(), *this);
1049  _M_before_begin._M_nxt = nullptr;
1050  _M_assign(__ht,
1051  [&__roan](const __node_type* __n)
1052  { return __roan(__n->_M_v()); });
1053  if (__former_buckets)
1054  _M_deallocate_buckets(__former_buckets, __former_bucket_count);
1055  }
1056  __catch(...)
1057  {
1058  if (__former_buckets)
1059  {
1060  // Restore previous buckets.
1061  _M_deallocate_buckets();
1062  _M_rehash_policy._M_reset(__former_state);
1063  _M_buckets = __former_buckets;
1064  _M_bucket_count = __former_bucket_count;
1065  }
1066  __builtin_memset(_M_buckets, 0,
1067  _M_bucket_count * sizeof(__bucket_type));
1068  __throw_exception_again;
1069  }
1070  return *this;
1071  }
1072 
1073  template<typename _Key, typename _Value,
1074  typename _Alloc, typename _ExtractKey, typename _Equal,
1075  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1076  typename _Traits>
1077  template<typename _NodeGenerator>
1078  void
1079  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1080  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1081  _M_assign(const _Hashtable& __ht, const _NodeGenerator& __node_gen)
1082  {
1083  __bucket_type* __buckets = nullptr;
1084  if (!_M_buckets)
1085  _M_buckets = __buckets = _M_allocate_buckets(_M_bucket_count);
1086 
1087  __try
1088  {
1089  if (!__ht._M_before_begin._M_nxt)
1090  return;
1091 
1092  // First deal with the special first node pointed to by
1093  // _M_before_begin.
1094  __node_type* __ht_n = __ht._M_begin();
1095  __node_type* __this_n = __node_gen(__ht_n);
1096  this->_M_copy_code(__this_n, __ht_n);
1097  _M_before_begin._M_nxt = __this_n;
1098  _M_buckets[_M_bucket_index(__this_n)] = &_M_before_begin;
1099 
1100  // Then deal with other nodes.
1101  __node_base* __prev_n = __this_n;
1102  for (__ht_n = __ht_n->_M_next(); __ht_n; __ht_n = __ht_n->_M_next())
1103  {
1104  __this_n = __node_gen(__ht_n);
1105  __prev_n->_M_nxt = __this_n;
1106  this->_M_copy_code(__this_n, __ht_n);
1107  size_type __bkt = _M_bucket_index(__this_n);
1108  if (!_M_buckets[__bkt])
1109  _M_buckets[__bkt] = __prev_n;
1110  __prev_n = __this_n;
1111  }
1112  }
1113  __catch(...)
1114  {
1115  clear();
1116  if (__buckets)
1117  _M_deallocate_buckets();
1118  __throw_exception_again;
1119  }
1120  }
1121 
1122  template<typename _Key, typename _Value,
1123  typename _Alloc, typename _ExtractKey, typename _Equal,
1124  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1125  typename _Traits>
1126  void
1127  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1128  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1129  _M_reset() noexcept
1130  {
1131  _M_rehash_policy._M_reset();
1132  _M_bucket_count = 1;
1133  _M_single_bucket = nullptr;
1134  _M_buckets = &_M_single_bucket;
1135  _M_before_begin._M_nxt = nullptr;
1136  _M_element_count = 0;
1137  }
1138 
1139  template<typename _Key, typename _Value,
1140  typename _Alloc, typename _ExtractKey, typename _Equal,
1141  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1142  typename _Traits>
1143  void
1144  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1145  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1146  _M_move_assign(_Hashtable&& __ht, std::true_type)
1147  {
1148  this->_M_deallocate_nodes(_M_begin());
1149  _M_deallocate_buckets();
1150  __hashtable_base::operator=(std::move(__ht));
1151  _M_rehash_policy = __ht._M_rehash_policy;
1152  if (!__ht._M_uses_single_bucket())
1153  _M_buckets = __ht._M_buckets;
1154  else
1155  {
1156  _M_buckets = &_M_single_bucket;
1157  _M_single_bucket = __ht._M_single_bucket;
1158  }
1159  _M_bucket_count = __ht._M_bucket_count;
1160  _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
1161  _M_element_count = __ht._M_element_count;
1162  std::__alloc_on_move(this->_M_node_allocator(), __ht._M_node_allocator());
1163 
1164  // Fix buckets containing the _M_before_begin pointers that can't be
1165  // moved.
1166  if (_M_begin())
1167  _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1168  __ht._M_reset();
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::false_type)
1179  {
1180  if (__ht._M_node_allocator() == this->_M_node_allocator())
1181  _M_move_assign(std::move(__ht), std::true_type());
1182  else
1183  {
1184  // Can't move memory, move elements then.
1185  __bucket_type* __former_buckets = nullptr;
1186  size_type __former_bucket_count = _M_bucket_count;
1187  const __rehash_state& __former_state = _M_rehash_policy._M_state();
1188 
1189  if (_M_bucket_count != __ht._M_bucket_count)
1190  {
1191  __former_buckets = _M_buckets;
1192  _M_buckets = _M_allocate_buckets(__ht._M_bucket_count);
1193  _M_bucket_count = __ht._M_bucket_count;
1194  }
1195  else
1196  __builtin_memset(_M_buckets, 0,
1197  _M_bucket_count * sizeof(__bucket_type));
1198 
1199  __try
1200  {
1201  __hashtable_base::operator=(std::move(__ht));
1202  _M_element_count = __ht._M_element_count;
1203  _M_rehash_policy = __ht._M_rehash_policy;
1204  __reuse_or_alloc_node_type __roan(_M_begin(), *this);
1205  _M_before_begin._M_nxt = nullptr;
1206  _M_assign(__ht,
1207  [&__roan](__node_type* __n)
1208  { return __roan(std::move_if_noexcept(__n->_M_v())); });
1209  __ht.clear();
1210  }
1211  __catch(...)
1212  {
1213  if (__former_buckets)
1214  {
1215  _M_deallocate_buckets();
1216  _M_rehash_policy._M_reset(__former_state);
1217  _M_buckets = __former_buckets;
1218  _M_bucket_count = __former_bucket_count;
1219  }
1220  __builtin_memset(_M_buckets, 0,
1221  _M_bucket_count * sizeof(__bucket_type));
1222  __throw_exception_again;
1223  }
1224  }
1225  }
1226 
1227  template<typename _Key, typename _Value,
1228  typename _Alloc, typename _ExtractKey, typename _Equal,
1229  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1230  typename _Traits>
1231  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1232  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1233  _Hashtable(const _Hashtable& __ht)
1234  : __hashtable_base(__ht),
1235  __map_base(__ht),
1236  __rehash_base(__ht),
1238  __node_alloc_traits::_S_select_on_copy(__ht._M_node_allocator())),
1239  _M_buckets(nullptr),
1240  _M_bucket_count(__ht._M_bucket_count),
1241  _M_element_count(__ht._M_element_count),
1242  _M_rehash_policy(__ht._M_rehash_policy)
1243  {
1244  _M_assign(__ht,
1245  [this](const __node_type* __n)
1246  { return this->_M_allocate_node(__n->_M_v()); });
1247  }
1248 
1249  template<typename _Key, typename _Value,
1250  typename _Alloc, typename _ExtractKey, typename _Equal,
1251  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1252  typename _Traits>
1253  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1254  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1255  _Hashtable(_Hashtable&& __ht) noexcept
1256  : __hashtable_base(__ht),
1257  __map_base(__ht),
1258  __rehash_base(__ht),
1259  __hashtable_alloc(std::move(__ht._M_base_alloc())),
1260  _M_buckets(__ht._M_buckets),
1261  _M_bucket_count(__ht._M_bucket_count),
1262  _M_before_begin(__ht._M_before_begin._M_nxt),
1263  _M_element_count(__ht._M_element_count),
1264  _M_rehash_policy(__ht._M_rehash_policy)
1265  {
1266  // Update, if necessary, buckets if __ht is using its single bucket.
1267  if (__ht._M_uses_single_bucket())
1268  {
1269  _M_buckets = &_M_single_bucket;
1270  _M_single_bucket = __ht._M_single_bucket;
1271  }
1272 
1273  // Update, if necessary, bucket pointing to before begin that hasn't
1274  // moved.
1275  if (_M_begin())
1276  _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1277 
1278  __ht._M_reset();
1279  }
1280 
1281  template<typename _Key, typename _Value,
1282  typename _Alloc, typename _ExtractKey, typename _Equal,
1283  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1284  typename _Traits>
1285  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1286  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1287  _Hashtable(const _Hashtable& __ht, const allocator_type& __a)
1288  : __hashtable_base(__ht),
1289  __map_base(__ht),
1290  __rehash_base(__ht),
1291  __hashtable_alloc(__node_alloc_type(__a)),
1292  _M_buckets(),
1293  _M_bucket_count(__ht._M_bucket_count),
1294  _M_element_count(__ht._M_element_count),
1295  _M_rehash_policy(__ht._M_rehash_policy)
1296  {
1297  _M_assign(__ht,
1298  [this](const __node_type* __n)
1299  { return this->_M_allocate_node(__n->_M_v()); });
1300  }
1301 
1302  template<typename _Key, typename _Value,
1303  typename _Alloc, typename _ExtractKey, typename _Equal,
1304  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1305  typename _Traits>
1306  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1307  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1308  _Hashtable(_Hashtable&& __ht, const allocator_type& __a)
1309  : __hashtable_base(__ht),
1310  __map_base(__ht),
1311  __rehash_base(__ht),
1312  __hashtable_alloc(__node_alloc_type(__a)),
1313  _M_buckets(nullptr),
1314  _M_bucket_count(__ht._M_bucket_count),
1315  _M_element_count(__ht._M_element_count),
1316  _M_rehash_policy(__ht._M_rehash_policy)
1317  {
1318  if (__ht._M_node_allocator() == this->_M_node_allocator())
1319  {
1320  if (__ht._M_uses_single_bucket())
1321  {
1322  _M_buckets = &_M_single_bucket;
1323  _M_single_bucket = __ht._M_single_bucket;
1324  }
1325  else
1326  _M_buckets = __ht._M_buckets;
1327 
1328  _M_before_begin._M_nxt = __ht._M_before_begin._M_nxt;
1329  // Update, if necessary, bucket pointing to before begin that hasn't
1330  // moved.
1331  if (_M_begin())
1332  _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1333  __ht._M_reset();
1334  }
1335  else
1336  {
1337  _M_assign(__ht,
1338  [this](__node_type* __n)
1339  {
1340  return this->_M_allocate_node(
1341  std::move_if_noexcept(__n->_M_v()));
1342  });
1343  __ht.clear();
1344  }
1345  }
1346 
1347  template<typename _Key, typename _Value,
1348  typename _Alloc, typename _ExtractKey, typename _Equal,
1349  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1350  typename _Traits>
1351  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1352  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1353  ~_Hashtable() noexcept
1354  {
1355  clear();
1356  _M_deallocate_buckets();
1357  }
1358 
1359  template<typename _Key, typename _Value,
1360  typename _Alloc, typename _ExtractKey, typename _Equal,
1361  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1362  typename _Traits>
1363  void
1364  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1365  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1366  swap(_Hashtable& __x)
1367  noexcept(__and_<__is_nothrow_swappable<_H1>,
1368  __is_nothrow_swappable<_Equal>>::value)
1369  {
1370  // The only base class with member variables is hash_code_base.
1371  // We define _Hash_code_base::_M_swap because different
1372  // specializations have different members.
1373  this->_M_swap(__x);
1374 
1375  std::__alloc_on_swap(this->_M_node_allocator(), __x._M_node_allocator());
1376  std::swap(_M_rehash_policy, __x._M_rehash_policy);
1377 
1378  // Deal properly with potentially moved instances.
1379  if (this->_M_uses_single_bucket())
1380  {
1381  if (!__x._M_uses_single_bucket())
1382  {
1383  _M_buckets = __x._M_buckets;
1384  __x._M_buckets = &__x._M_single_bucket;
1385  }
1386  }
1387  else if (__x._M_uses_single_bucket())
1388  {
1389  __x._M_buckets = _M_buckets;
1390  _M_buckets = &_M_single_bucket;
1391  }
1392  else
1393  std::swap(_M_buckets, __x._M_buckets);
1394 
1395  std::swap(_M_bucket_count, __x._M_bucket_count);
1396  std::swap(_M_before_begin._M_nxt, __x._M_before_begin._M_nxt);
1397  std::swap(_M_element_count, __x._M_element_count);
1398  std::swap(_M_single_bucket, __x._M_single_bucket);
1399 
1400  // Fix buckets containing the _M_before_begin pointers that can't be
1401  // swapped.
1402  if (_M_begin())
1403  _M_buckets[_M_bucket_index(_M_begin())] = &_M_before_begin;
1404 
1405  if (__x._M_begin())
1406  __x._M_buckets[__x._M_bucket_index(__x._M_begin())]
1407  = &__x._M_before_begin;
1408  }
1409 
1410  template<typename _Key, typename _Value,
1411  typename _Alloc, typename _ExtractKey, typename _Equal,
1412  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1413  typename _Traits>
1414  auto
1415  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1416  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1417  find(const key_type& __k)
1418  -> iterator
1419  {
1420  __hash_code __code = this->_M_hash_code(__k);
1421  std::size_t __n = _M_bucket_index(__k, __code);
1422  __node_type* __p = _M_find_node(__n, __k, __code);
1423  return __p ? iterator(__p) : end();
1424  }
1425 
1426  template<typename _Key, typename _Value,
1427  typename _Alloc, typename _ExtractKey, typename _Equal,
1428  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1429  typename _Traits>
1430  auto
1431  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1432  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1433  find(const key_type& __k) const
1434  -> const_iterator
1435  {
1436  __hash_code __code = this->_M_hash_code(__k);
1437  std::size_t __n = _M_bucket_index(__k, __code);
1438  __node_type* __p = _M_find_node(__n, __k, __code);
1439  return __p ? const_iterator(__p) : end();
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  count(const key_type& __k) const
1450  -> size_type
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_bucket_begin(__n);
1455  if (!__p)
1456  return 0;
1457 
1458  std::size_t __result = 0;
1459  for (;; __p = __p->_M_next())
1460  {
1461  if (this->_M_equals(__k, __code, __p))
1462  ++__result;
1463  else if (__result)
1464  // All equivalent values are next to each other, if we
1465  // found a non-equivalent value after an equivalent one it
1466  // means that we won't find any new equivalent value.
1467  break;
1468  if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
1469  break;
1470  }
1471  return __result;
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  equal_range(const key_type& __k)
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_find_node(__n, __k, __code);
1487 
1488  if (__p)
1489  {
1490  __node_type* __p1 = __p->_M_next();
1491  while (__p1 && _M_bucket_index(__p1) == __n
1492  && this->_M_equals(__k, __code, __p1))
1493  __p1 = __p1->_M_next();
1494 
1495  return std::make_pair(iterator(__p), iterator(__p1));
1496  }
1497  else
1498  return std::make_pair(end(), end());
1499  }
1500 
1501  template<typename _Key, typename _Value,
1502  typename _Alloc, typename _ExtractKey, typename _Equal,
1503  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1504  typename _Traits>
1505  auto
1506  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1507  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1508  equal_range(const key_type& __k) const
1510  {
1511  __hash_code __code = this->_M_hash_code(__k);
1512  std::size_t __n = _M_bucket_index(__k, __code);
1513  __node_type* __p = _M_find_node(__n, __k, __code);
1514 
1515  if (__p)
1516  {
1517  __node_type* __p1 = __p->_M_next();
1518  while (__p1 && _M_bucket_index(__p1) == __n
1519  && this->_M_equals(__k, __code, __p1))
1520  __p1 = __p1->_M_next();
1521 
1522  return std::make_pair(const_iterator(__p), const_iterator(__p1));
1523  }
1524  else
1525  return std::make_pair(end(), end());
1526  }
1527 
1528  // Find the node whose key compares equal to k in the bucket n.
1529  // Return nullptr if no node is found.
1530  template<typename _Key, typename _Value,
1531  typename _Alloc, typename _ExtractKey, typename _Equal,
1532  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1533  typename _Traits>
1534  auto
1535  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1536  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1537  _M_find_before_node(size_type __n, const key_type& __k,
1538  __hash_code __code) const
1539  -> __node_base*
1540  {
1541  __node_base* __prev_p = _M_buckets[__n];
1542  if (!__prev_p)
1543  return nullptr;
1544 
1545  for (__node_type* __p = static_cast<__node_type*>(__prev_p->_M_nxt);;
1546  __p = __p->_M_next())
1547  {
1548  if (this->_M_equals(__k, __code, __p))
1549  return __prev_p;
1550 
1551  if (!__p->_M_nxt || _M_bucket_index(__p->_M_next()) != __n)
1552  break;
1553  __prev_p = __p;
1554  }
1555  return nullptr;
1556  }
1557 
1558  template<typename _Key, typename _Value,
1559  typename _Alloc, typename _ExtractKey, typename _Equal,
1560  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1561  typename _Traits>
1562  void
1563  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1564  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1565  _M_insert_bucket_begin(size_type __bkt, __node_type* __node)
1566  {
1567  if (_M_buckets[__bkt])
1568  {
1569  // Bucket is not empty, we just need to insert the new node
1570  // after the bucket before begin.
1571  __node->_M_nxt = _M_buckets[__bkt]->_M_nxt;
1572  _M_buckets[__bkt]->_M_nxt = __node;
1573  }
1574  else
1575  {
1576  // The bucket is empty, the new node is inserted at the
1577  // beginning of the singly-linked list and the bucket will
1578  // contain _M_before_begin pointer.
1579  __node->_M_nxt = _M_before_begin._M_nxt;
1580  _M_before_begin._M_nxt = __node;
1581  if (__node->_M_nxt)
1582  // We must update former begin bucket that is pointing to
1583  // _M_before_begin.
1584  _M_buckets[_M_bucket_index(__node->_M_next())] = __node;
1585  _M_buckets[__bkt] = &_M_before_begin;
1586  }
1587  }
1588 
1589  template<typename _Key, typename _Value,
1590  typename _Alloc, typename _ExtractKey, typename _Equal,
1591  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1592  typename _Traits>
1593  void
1594  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1595  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1596  _M_remove_bucket_begin(size_type __bkt, __node_type* __next,
1597  size_type __next_bkt)
1598  {
1599  if (!__next || __next_bkt != __bkt)
1600  {
1601  // Bucket is now empty
1602  // First update next bucket if any
1603  if (__next)
1604  _M_buckets[__next_bkt] = _M_buckets[__bkt];
1605 
1606  // Second update before begin node if necessary
1607  if (&_M_before_begin == _M_buckets[__bkt])
1608  _M_before_begin._M_nxt = __next;
1609  _M_buckets[__bkt] = nullptr;
1610  }
1611  }
1612 
1613  template<typename _Key, typename _Value,
1614  typename _Alloc, typename _ExtractKey, typename _Equal,
1615  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1616  typename _Traits>
1617  auto
1618  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1619  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1620  _M_get_previous_node(size_type __bkt, __node_base* __n)
1621  -> __node_base*
1622  {
1623  __node_base* __prev_n = _M_buckets[__bkt];
1624  while (__prev_n->_M_nxt != __n)
1625  __prev_n = __prev_n->_M_nxt;
1626  return __prev_n;
1627  }
1628 
1629  template<typename _Key, typename _Value,
1630  typename _Alloc, typename _ExtractKey, typename _Equal,
1631  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1632  typename _Traits>
1633  template<typename... _Args>
1634  auto
1635  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1636  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1637  _M_emplace(std::true_type, _Args&&... __args)
1639  {
1640  // First build the node to get access to the hash code
1641  __node_type* __node = this->_M_allocate_node(std::forward<_Args>(__args)...);
1642  const key_type& __k = this->_M_extract()(__node->_M_v());
1643  __hash_code __code;
1644  __try
1645  {
1646  __code = this->_M_hash_code(__k);
1647  }
1648  __catch(...)
1649  {
1650  this->_M_deallocate_node(__node);
1651  __throw_exception_again;
1652  }
1653 
1654  size_type __bkt = _M_bucket_index(__k, __code);
1655  if (__node_type* __p = _M_find_node(__bkt, __k, __code))
1656  {
1657  // There is already an equivalent node, no insertion
1658  this->_M_deallocate_node(__node);
1659  return std::make_pair(iterator(__p), false);
1660  }
1661 
1662  // Insert the node
1663  return std::make_pair(_M_insert_unique_node(__bkt, __code, __node),
1664  true);
1665  }
1666 
1667  template<typename _Key, typename _Value,
1668  typename _Alloc, typename _ExtractKey, typename _Equal,
1669  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1670  typename _Traits>
1671  template<typename... _Args>
1672  auto
1673  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1674  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1675  _M_emplace(const_iterator __hint, std::false_type, _Args&&... __args)
1676  -> iterator
1677  {
1678  // First build the node to get its hash code.
1679  __node_type* __node =
1680  this->_M_allocate_node(std::forward<_Args>(__args)...);
1681 
1682  __hash_code __code;
1683  __try
1684  {
1685  __code = this->_M_hash_code(this->_M_extract()(__node->_M_v()));
1686  }
1687  __catch(...)
1688  {
1689  this->_M_deallocate_node(__node);
1690  __throw_exception_again;
1691  }
1692 
1693  return _M_insert_multi_node(__hint._M_cur, __code, __node);
1694  }
1695 
1696  template<typename _Key, typename _Value,
1697  typename _Alloc, typename _ExtractKey, typename _Equal,
1698  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1699  typename _Traits>
1700  auto
1701  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1702  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1703  _M_insert_unique_node(size_type __bkt, __hash_code __code,
1704  __node_type* __node)
1705  -> iterator
1706  {
1707  const __rehash_state& __saved_state = _M_rehash_policy._M_state();
1708  std::pair<bool, std::size_t> __do_rehash
1709  = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count, 1);
1710 
1711  __try
1712  {
1713  if (__do_rehash.first)
1714  {
1715  _M_rehash(__do_rehash.second, __saved_state);
1716  __bkt = _M_bucket_index(this->_M_extract()(__node->_M_v()), __code);
1717  }
1718 
1719  this->_M_store_code(__node, __code);
1720 
1721  // Always insert at the beginning of the bucket.
1722  _M_insert_bucket_begin(__bkt, __node);
1723  ++_M_element_count;
1724  return iterator(__node);
1725  }
1726  __catch(...)
1727  {
1728  this->_M_deallocate_node(__node);
1729  __throw_exception_again;
1730  }
1731  }
1732 
1733  // Insert node, in bucket bkt if no rehash (assumes no element with its key
1734  // already present). Take ownership of the node, deallocate it on exception.
1735  template<typename _Key, typename _Value,
1736  typename _Alloc, typename _ExtractKey, typename _Equal,
1737  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1738  typename _Traits>
1739  auto
1740  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1741  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1742  _M_insert_multi_node(__node_type* __hint, __hash_code __code,
1743  __node_type* __node)
1744  -> iterator
1745  {
1746  const __rehash_state& __saved_state = _M_rehash_policy._M_state();
1747  std::pair<bool, std::size_t> __do_rehash
1748  = _M_rehash_policy._M_need_rehash(_M_bucket_count, _M_element_count, 1);
1749 
1750  __try
1751  {
1752  if (__do_rehash.first)
1753  _M_rehash(__do_rehash.second, __saved_state);
1754 
1755  this->_M_store_code(__node, __code);
1756  const key_type& __k = this->_M_extract()(__node->_M_v());
1757  size_type __bkt = _M_bucket_index(__k, __code);
1758 
1759  // Find the node before an equivalent one or use hint if it exists and
1760  // if it is equivalent.
1761  __node_base* __prev
1762  = __builtin_expect(__hint != nullptr, false)
1763  && this->_M_equals(__k, __code, __hint)
1764  ? __hint
1765  : _M_find_before_node(__bkt, __k, __code);
1766  if (__prev)
1767  {
1768  // Insert after the node before the equivalent one.
1769  __node->_M_nxt = __prev->_M_nxt;
1770  __prev->_M_nxt = __node;
1771  if (__builtin_expect(__prev == __hint, false))
1772  // hint might be the last bucket node, in this case we need to
1773  // update next bucket.
1774  if (__node->_M_nxt
1775  && !this->_M_equals(__k, __code, __node->_M_next()))
1776  {
1777  size_type __next_bkt = _M_bucket_index(__node->_M_next());
1778  if (__next_bkt != __bkt)
1779  _M_buckets[__next_bkt] = __node;
1780  }
1781  }
1782  else
1783  // The inserted node has no equivalent in the
1784  // hashtable. We must insert the new node at the
1785  // beginning of the bucket to preserve equivalent
1786  // elements' relative positions.
1787  _M_insert_bucket_begin(__bkt, __node);
1788  ++_M_element_count;
1789  return iterator(__node);
1790  }
1791  __catch(...)
1792  {
1793  this->_M_deallocate_node(__node);
1794  __throw_exception_again;
1795  }
1796  }
1797 
1798  // Insert v if no element with its key is already present.
1799  template<typename _Key, typename _Value,
1800  typename _Alloc, typename _ExtractKey, typename _Equal,
1801  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1802  typename _Traits>
1803  template<typename _Arg, typename _NodeGenerator>
1804  auto
1805  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1806  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1807  _M_insert(_Arg&& __v, const _NodeGenerator& __node_gen, std::true_type)
1809  {
1810  const key_type& __k = this->_M_extract()(__v);
1811  __hash_code __code = this->_M_hash_code(__k);
1812  size_type __bkt = _M_bucket_index(__k, __code);
1813 
1814  __node_type* __n = _M_find_node(__bkt, __k, __code);
1815  if (__n)
1816  return std::make_pair(iterator(__n), false);
1817 
1818  __n = __node_gen(std::forward<_Arg>(__v));
1819  return std::make_pair(_M_insert_unique_node(__bkt, __code, __n), true);
1820  }
1821 
1822  // Insert v unconditionally.
1823  template<typename _Key, typename _Value,
1824  typename _Alloc, typename _ExtractKey, typename _Equal,
1825  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1826  typename _Traits>
1827  template<typename _Arg, typename _NodeGenerator>
1828  auto
1829  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1830  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1831  _M_insert(const_iterator __hint, _Arg&& __v,
1832  const _NodeGenerator& __node_gen, std::false_type)
1833  -> iterator
1834  {
1835  // First compute the hash code so that we don't do anything if it
1836  // throws.
1837  __hash_code __code = this->_M_hash_code(this->_M_extract()(__v));
1838 
1839  // Second allocate new node so that we don't rehash if it throws.
1840  __node_type* __node = __node_gen(std::forward<_Arg>(__v));
1841 
1842  return _M_insert_multi_node(__hint._M_cur, __code, __node);
1843  }
1844 
1845  template<typename _Key, typename _Value,
1846  typename _Alloc, typename _ExtractKey, typename _Equal,
1847  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1848  typename _Traits>
1849  auto
1850  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1851  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1852  erase(const_iterator __it)
1853  -> iterator
1854  {
1855  __node_type* __n = __it._M_cur;
1856  std::size_t __bkt = _M_bucket_index(__n);
1857 
1858  // Look for previous node to unlink it from the erased one, this
1859  // is why we need buckets to contain the before begin to make
1860  // this search fast.
1861  __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
1862  return _M_erase(__bkt, __prev_n, __n);
1863  }
1864 
1865  template<typename _Key, typename _Value,
1866  typename _Alloc, typename _ExtractKey, typename _Equal,
1867  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1868  typename _Traits>
1869  auto
1870  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1871  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1872  _M_erase(size_type __bkt, __node_base* __prev_n, __node_type* __n)
1873  -> iterator
1874  {
1875  if (__prev_n == _M_buckets[__bkt])
1876  _M_remove_bucket_begin(__bkt, __n->_M_next(),
1877  __n->_M_nxt ? _M_bucket_index(__n->_M_next()) : 0);
1878  else if (__n->_M_nxt)
1879  {
1880  size_type __next_bkt = _M_bucket_index(__n->_M_next());
1881  if (__next_bkt != __bkt)
1882  _M_buckets[__next_bkt] = __prev_n;
1883  }
1884 
1885  __prev_n->_M_nxt = __n->_M_nxt;
1886  iterator __result(__n->_M_next());
1887  this->_M_deallocate_node(__n);
1888  --_M_element_count;
1889 
1890  return __result;
1891  }
1892 
1893  template<typename _Key, typename _Value,
1894  typename _Alloc, typename _ExtractKey, typename _Equal,
1895  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1896  typename _Traits>
1897  auto
1898  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1899  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1900  _M_erase(std::true_type, const key_type& __k)
1901  -> size_type
1902  {
1903  __hash_code __code = this->_M_hash_code(__k);
1904  std::size_t __bkt = _M_bucket_index(__k, __code);
1905 
1906  // Look for the node before the first matching node.
1907  __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
1908  if (!__prev_n)
1909  return 0;
1910 
1911  // We found a matching node, erase it.
1912  __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
1913  _M_erase(__bkt, __prev_n, __n);
1914  return 1;
1915  }
1916 
1917  template<typename _Key, typename _Value,
1918  typename _Alloc, typename _ExtractKey, typename _Equal,
1919  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1920  typename _Traits>
1921  auto
1922  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1923  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1924  _M_erase(std::false_type, const key_type& __k)
1925  -> size_type
1926  {
1927  __hash_code __code = this->_M_hash_code(__k);
1928  std::size_t __bkt = _M_bucket_index(__k, __code);
1929 
1930  // Look for the node before the first matching node.
1931  __node_base* __prev_n = _M_find_before_node(__bkt, __k, __code);
1932  if (!__prev_n)
1933  return 0;
1934 
1935  // _GLIBCXX_RESOLVE_LIB_DEFECTS
1936  // 526. Is it undefined if a function in the standard changes
1937  // in parameters?
1938  // We use one loop to find all matching nodes and another to deallocate
1939  // them so that the key stays valid during the first loop. It might be
1940  // invalidated indirectly when destroying nodes.
1941  __node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);
1942  __node_type* __n_last = __n;
1943  std::size_t __n_last_bkt = __bkt;
1944  do
1945  {
1946  __n_last = __n_last->_M_next();
1947  if (!__n_last)
1948  break;
1949  __n_last_bkt = _M_bucket_index(__n_last);
1950  }
1951  while (__n_last_bkt == __bkt && this->_M_equals(__k, __code, __n_last));
1952 
1953  // Deallocate nodes.
1954  size_type __result = 0;
1955  do
1956  {
1957  __node_type* __p = __n->_M_next();
1958  this->_M_deallocate_node(__n);
1959  __n = __p;
1960  ++__result;
1961  --_M_element_count;
1962  }
1963  while (__n != __n_last);
1964 
1965  if (__prev_n == _M_buckets[__bkt])
1966  _M_remove_bucket_begin(__bkt, __n_last, __n_last_bkt);
1967  else if (__n_last && __n_last_bkt != __bkt)
1968  _M_buckets[__n_last_bkt] = __prev_n;
1969  __prev_n->_M_nxt = __n_last;
1970  return __result;
1971  }
1972 
1973  template<typename _Key, typename _Value,
1974  typename _Alloc, typename _ExtractKey, typename _Equal,
1975  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1976  typename _Traits>
1977  auto
1978  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1979  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
1980  erase(const_iterator __first, const_iterator __last)
1981  -> iterator
1982  {
1983  __node_type* __n = __first._M_cur;
1984  __node_type* __last_n = __last._M_cur;
1985  if (__n == __last_n)
1986  return iterator(__n);
1987 
1988  std::size_t __bkt = _M_bucket_index(__n);
1989 
1990  __node_base* __prev_n = _M_get_previous_node(__bkt, __n);
1991  bool __is_bucket_begin = __n == _M_bucket_begin(__bkt);
1992  std::size_t __n_bkt = __bkt;
1993  for (;;)
1994  {
1995  do
1996  {
1997  __node_type* __tmp = __n;
1998  __n = __n->_M_next();
1999  this->_M_deallocate_node(__tmp);
2000  --_M_element_count;
2001  if (!__n)
2002  break;
2003  __n_bkt = _M_bucket_index(__n);
2004  }
2005  while (__n != __last_n && __n_bkt == __bkt);
2006  if (__is_bucket_begin)
2007  _M_remove_bucket_begin(__bkt, __n, __n_bkt);
2008  if (__n == __last_n)
2009  break;
2010  __is_bucket_begin = true;
2011  __bkt = __n_bkt;
2012  }
2013 
2014  if (__n && (__n_bkt != __bkt || __is_bucket_begin))
2015  _M_buckets[__n_bkt] = __prev_n;
2016  __prev_n->_M_nxt = __n;
2017  return iterator(__n);
2018  }
2019 
2020  template<typename _Key, typename _Value,
2021  typename _Alloc, typename _ExtractKey, typename _Equal,
2022  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2023  typename _Traits>
2024  void
2025  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2026  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2027  clear() noexcept
2028  {
2029  this->_M_deallocate_nodes(_M_begin());
2030  __builtin_memset(_M_buckets, 0, _M_bucket_count * sizeof(__bucket_type));
2031  _M_element_count = 0;
2032  _M_before_begin._M_nxt = nullptr;
2033  }
2034 
2035  template<typename _Key, typename _Value,
2036  typename _Alloc, typename _ExtractKey, typename _Equal,
2037  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2038  typename _Traits>
2039  void
2040  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2041  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2042  rehash(size_type __n)
2043  {
2044  const __rehash_state& __saved_state = _M_rehash_policy._M_state();
2045  std::size_t __buckets
2046  = std::max(_M_rehash_policy._M_bkt_for_elements(_M_element_count + 1),
2047  __n);
2048  __buckets = _M_rehash_policy._M_next_bkt(__buckets);
2049 
2050  if (__buckets != _M_bucket_count)
2051  _M_rehash(__buckets, __saved_state);
2052  else
2053  // No rehash, restore previous state to keep a consistent state.
2054  _M_rehash_policy._M_reset(__saved_state);
2055  }
2056 
2057  template<typename _Key, typename _Value,
2058  typename _Alloc, typename _ExtractKey, typename _Equal,
2059  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2060  typename _Traits>
2061  void
2062  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2063  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2064  _M_rehash(size_type __n, const __rehash_state& __state)
2065  {
2066  __try
2067  {
2068  _M_rehash_aux(__n, __unique_keys());
2069  }
2070  __catch(...)
2071  {
2072  // A failure here means that buckets allocation failed. We only
2073  // have to restore hash policy previous state.
2074  _M_rehash_policy._M_reset(__state);
2075  __throw_exception_again;
2076  }
2077  }
2078 
2079  // Rehash when there is no equivalent elements.
2080  template<typename _Key, typename _Value,
2081  typename _Alloc, typename _ExtractKey, typename _Equal,
2082  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2083  typename _Traits>
2084  void
2085  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2086  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2087  _M_rehash_aux(size_type __n, std::true_type)
2088  {
2089  __bucket_type* __new_buckets = _M_allocate_buckets(__n);
2090  __node_type* __p = _M_begin();
2091  _M_before_begin._M_nxt = nullptr;
2092  std::size_t __bbegin_bkt = 0;
2093  while (__p)
2094  {
2095  __node_type* __next = __p->_M_next();
2096  std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
2097  if (!__new_buckets[__bkt])
2098  {
2099  __p->_M_nxt = _M_before_begin._M_nxt;
2100  _M_before_begin._M_nxt = __p;
2101  __new_buckets[__bkt] = &_M_before_begin;
2102  if (__p->_M_nxt)
2103  __new_buckets[__bbegin_bkt] = __p;
2104  __bbegin_bkt = __bkt;
2105  }
2106  else
2107  {
2108  __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2109  __new_buckets[__bkt]->_M_nxt = __p;
2110  }
2111  __p = __next;
2112  }
2113 
2114  _M_deallocate_buckets();
2115  _M_bucket_count = __n;
2116  _M_buckets = __new_buckets;
2117  }
2118 
2119  // Rehash when there can be equivalent elements, preserve their relative
2120  // order.
2121  template<typename _Key, typename _Value,
2122  typename _Alloc, typename _ExtractKey, typename _Equal,
2123  typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
2124  typename _Traits>
2125  void
2126  _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
2127  _H1, _H2, _Hash, _RehashPolicy, _Traits>::
2128  _M_rehash_aux(size_type __n, std::false_type)
2129  {
2130  __bucket_type* __new_buckets = _M_allocate_buckets(__n);
2131 
2132  __node_type* __p = _M_begin();
2133  _M_before_begin._M_nxt = nullptr;
2134  std::size_t __bbegin_bkt = 0;
2135  std::size_t __prev_bkt = 0;
2136  __node_type* __prev_p = nullptr;
2137  bool __check_bucket = false;
2138 
2139  while (__p)
2140  {
2141  __node_type* __next = __p->_M_next();
2142  std::size_t __bkt = __hash_code_base::_M_bucket_index(__p, __n);
2143 
2144  if (__prev_p && __prev_bkt == __bkt)
2145  {
2146  // Previous insert was already in this bucket, we insert after
2147  // the previously inserted one to preserve equivalent elements
2148  // relative order.
2149  __p->_M_nxt = __prev_p->_M_nxt;
2150  __prev_p->_M_nxt = __p;
2151 
2152  // Inserting after a node in a bucket require to check that we
2153  // haven't change the bucket last node, in this case next
2154  // bucket containing its before begin node must be updated. We
2155  // schedule a check as soon as we move out of the sequence of
2156  // equivalent nodes to limit the number of checks.
2157  __check_bucket = true;
2158  }
2159  else
2160  {
2161  if (__check_bucket)
2162  {
2163  // Check if we shall update the next bucket because of
2164  // insertions into __prev_bkt bucket.
2165  if (__prev_p->_M_nxt)
2166  {
2167  std::size_t __next_bkt
2168  = __hash_code_base::_M_bucket_index(__prev_p->_M_next(),
2169  __n);
2170  if (__next_bkt != __prev_bkt)
2171  __new_buckets[__next_bkt] = __prev_p;
2172  }
2173  __check_bucket = false;
2174  }
2175 
2176  if (!__new_buckets[__bkt])
2177  {
2178  __p->_M_nxt = _M_before_begin._M_nxt;
2179  _M_before_begin._M_nxt = __p;
2180  __new_buckets[__bkt] = &_M_before_begin;
2181  if (__p->_M_nxt)
2182  __new_buckets[__bbegin_bkt] = __p;
2183  __bbegin_bkt = __bkt;
2184  }
2185  else
2186  {
2187  __p->_M_nxt = __new_buckets[__bkt]->_M_nxt;
2188  __new_buckets[__bkt]->_M_nxt = __p;
2189  }
2190  }
2191  __prev_p = __p;
2192  __prev_bkt = __bkt;
2193  __p = __next;
2194  }
2195 
2196  if (__check_bucket && __prev_p->_M_nxt)
2197  {
2198  std::size_t __next_bkt
2199  = __hash_code_base::_M_bucket_index(__prev_p->_M_next(), __n);
2200  if (__next_bkt != __prev_bkt)
2201  __new_buckets[__next_bkt] = __prev_p;
2202  }
2203 
2204  _M_deallocate_buckets();
2205  _M_bucket_count = __n;
2206  _M_buckets = __new_buckets;
2207  }
2208 
2209 #if __cplusplus > 201402L
2210  template<typename, typename, typename> class _Hash_merge_helper { };
2211 #endif // C++17
2212 
2213 _GLIBCXX_END_NAMESPACE_VERSION
2214 } // namespace std
2215 
2216 #endif // _HASHTABLE_H
Uniform interface to C++98 and C++11 allocators.
constexpr const _Tp * end(initializer_list< _Tp > __ils) noexcept
Return an iterator pointing to one past the last element of the initializer_list. ...
integral_constant
Definition: type_traits:69
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
constexpr const _Tp * begin(initializer_list< _Tp > __ils) noexcept
Return an iterator pointing to the first element of the initializer_list.
ISO C++ entities toplevel namespace is std.
Uniform interface to all allocator types.
Node iterators, used to iterate through all the hashtable.
_GLIBCXX17_CONSTEXPR iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
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:519
_Tp exchange(_Tp &__obj, _Up &&__new_val)
Assign __new_val to __obj and return its previous value.
Definition: utility:281
_GLIBCXX14_CONSTEXPR const _Tp & max(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:219
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition: type_traits:87
_T1 first
second_type is the second bound type
Definition: stl_pair.h:203
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:118
_T2 second
first is a copy of the first object
Definition: stl_pair.h:204
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
Struct holding two objects of arbitrary type.
Definition: stl_pair.h:198
Node const_iterators, used to iterate through all the hashtable.