libstdc++
hashtable_policy.h
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1 // Internal policy header for unordered_set and unordered_map -*- C++ -*-
2 
3 // Copyright (C) 2010-2025 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /** @file bits/hashtable_policy.h
26  * This is an internal header file, included by other library headers.
27  * Do not attempt to use it directly.
28  * @headername{unordered_map,unordered_set}
29  */
30 
31 #ifndef _HASHTABLE_POLICY_H
32 #define _HASHTABLE_POLICY_H 1
33 
34 #include <tuple> // for std::tuple, std::forward_as_tuple
35 #include <bits/functional_hash.h> // for __is_fast_hash
36 #include <bits/stl_algobase.h> // for std::min
37 #include <bits/stl_pair.h> // for std::pair
38 #include <ext/aligned_buffer.h> // for __gnu_cxx::__aligned_buffer
39 #include <ext/alloc_traits.h> // for std::__alloc_rebind
40 #include <ext/numeric_traits.h> // for __gnu_cxx::__int_traits
41 
42 namespace std _GLIBCXX_VISIBILITY(default)
43 {
44 _GLIBCXX_BEGIN_NAMESPACE_VERSION
45 /// @cond undocumented
46 
47  template<typename _Key, typename _Value, typename _Alloc,
48  typename _ExtractKey, typename _Equal,
49  typename _Hash, typename _RangeHash, typename _Unused,
50  typename _RehashPolicy, typename _Traits>
51  class _Hashtable;
52 
53 namespace __detail
54 {
55  /**
56  * @defgroup hashtable-detail Base and Implementation Classes
57  * @ingroup unordered_associative_containers
58  * @{
59  */
60  template<typename _Key, typename _Value, typename _ExtractKey,
61  typename _Equal, typename _Hash, typename _RangeHash,
62  typename _Unused, typename _Traits>
63  struct _Hashtable_base;
64 
65 #pragma GCC diagnostic push
66 #pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
67  // Helper function: return distance(first, last) for forward
68  // iterators, or 0/1 for input iterators.
69  template<typename _Iterator>
71  __distance_fw(_Iterator __first, _Iterator __last)
72  {
74  if constexpr (is_convertible<_Cat, forward_iterator_tag>::value)
75  return std::distance(__first, __last);
76  else
77  return __first != __last ? 1 : 0;
78  }
79 #pragma GCC diagnostic pop
80 
81  struct _Identity
82  {
83  template<typename _Tp>
84  _Tp&&
85  operator()(_Tp&& __x) const noexcept
86  { return std::forward<_Tp>(__x); }
87  };
88 
89  struct _Select1st
90  {
91  template<typename _Pair>
92  struct __1st_type;
93 
94  template<typename _Tp, typename _Up>
95  struct __1st_type<pair<_Tp, _Up>>
96  { using type = _Tp; };
97 
98  template<typename _Tp, typename _Up>
99  struct __1st_type<const pair<_Tp, _Up>>
100  { using type = const _Tp; };
101 
102  template<typename _Pair>
103  struct __1st_type<_Pair&>
104  { using type = typename __1st_type<_Pair>::type&; };
105 
106  template<typename _Tp>
107  typename __1st_type<_Tp>::type&&
108  operator()(_Tp&& __x) const noexcept
109  { return std::forward<_Tp>(__x).first; }
110  };
111 
112  template<typename _ExKey>
113  struct _NodeBuilder;
114 
115  template<>
116  struct _NodeBuilder<_Select1st>
117  {
118  template<typename _Kt, typename _Arg, typename _NodeGenerator>
119  static auto
120  _S_build(_Kt&& __k, _Arg&& __arg, _NodeGenerator& __node_gen)
121  -> typename _NodeGenerator::__node_ptr
122  {
123  return __node_gen(std::forward<_Kt>(__k),
124  std::forward<_Arg>(__arg).second);
125  }
126  };
127 
128  template<>
129  struct _NodeBuilder<_Identity>
130  {
131  template<typename _Kt, typename _Arg, typename _NodeGenerator>
132  static auto
133  _S_build(_Kt&& __k, _Arg&&, _NodeGenerator& __node_gen)
134  -> typename _NodeGenerator::__node_ptr
135  { return __node_gen(std::forward<_Kt>(__k)); }
136  };
137 
138  template<typename _HashtableAlloc, typename _NodePtr>
139  struct _NodePtrGuard
140  {
141  _HashtableAlloc& _M_h;
142  _NodePtr _M_ptr;
143 
144  ~_NodePtrGuard()
145  {
146  if (_M_ptr)
147  _M_h._M_deallocate_node_ptr(_M_ptr);
148  }
149  };
150 
151  template<typename _NodeAlloc>
152  struct _Hashtable_alloc;
153 
154  // Functor recycling a pool of nodes and using allocation once the pool is
155  // empty.
156  template<typename _NodeAlloc>
157  struct _ReuseOrAllocNode
158  {
159  private:
160  using __node_alloc_type = _NodeAlloc;
161  using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
162  using __node_alloc_traits =
163  typename __hashtable_alloc::__node_alloc_traits;
164 
165  public:
166  using __node_ptr = typename __hashtable_alloc::__node_ptr;
167 
168  _ReuseOrAllocNode(__node_ptr __nodes, __hashtable_alloc& __h)
169  : _M_nodes(__nodes), _M_h(__h) { }
170  _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;
171 
172  ~_ReuseOrAllocNode()
173  { _M_h._M_deallocate_nodes(_M_nodes); }
174 
175 #pragma GCC diagnostic push
176 #pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
177  template<typename _Arg>
178  __node_ptr
179  operator()(_Arg&& __arg)
180  {
181  if (!_M_nodes)
182  return _M_h._M_allocate_node(std::forward<_Arg>(__arg));
183 
184  using value_type = typename _NodeAlloc::value_type::value_type;
185 
186  __node_ptr __node = _M_nodes;
187  if constexpr (is_assignable<value_type&, _Arg>::value)
188  {
189  __node->_M_v() = std::forward<_Arg>(__arg);
190  _M_nodes = _M_nodes->_M_next();
191  __node->_M_nxt = nullptr;
192  }
193  else
194  {
195  _M_nodes = _M_nodes->_M_next();
196  __node->_M_nxt = nullptr;
197  auto& __a = _M_h._M_node_allocator();
198  __node_alloc_traits::destroy(__a, __node->_M_valptr());
199  _NodePtrGuard<__hashtable_alloc, __node_ptr>
200  __guard{ _M_h, __node };
201  __node_alloc_traits::construct(__a, __node->_M_valptr(),
202  std::forward<_Arg>(__arg));
203  __guard._M_ptr = nullptr;
204  }
205  return __node;
206  }
207 #pragma GCC diagnostic pop
208 
209  private:
210  __node_ptr _M_nodes;
211  __hashtable_alloc& _M_h;
212  };
213 
214  // Functor similar to the previous one but without any pool of nodes to
215  // recycle.
216  template<typename _NodeAlloc>
217  struct _AllocNode
218  {
219  private:
220  using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
221 
222  public:
223  using __node_ptr = typename __hashtable_alloc::__node_ptr;
224 
225  _AllocNode(__hashtable_alloc& __h)
226  : _M_h(__h) { }
227 
228  template<typename... _Args>
229  __node_ptr
230  operator()(_Args&&... __args) const
231  { return _M_h._M_allocate_node(std::forward<_Args>(__args)...); }
232 
233  private:
234  __hashtable_alloc& _M_h;
235  };
236 
237  // Auxiliary types used for all instantiations of _Hashtable nodes
238  // and iterators.
239 
240  /**
241  * struct _Hashtable_traits
242  *
243  * Important traits for hash tables.
244  *
245  * @tparam _Cache_hash_code Boolean value. True if the value of
246  * the hash function is stored along with the value. This is a
247  * time-space tradeoff. Storing it may improve lookup speed by
248  * reducing the number of times we need to call the _Hash or _Equal
249  * functors.
250  *
251  * @tparam _Constant_iterators Boolean value. True if iterator and
252  * const_iterator are both constant iterator types. This is true
253  * for unordered_set and unordered_multiset, false for
254  * unordered_map and unordered_multimap.
255  *
256  * @tparam _Unique_keys Boolean value. True if the return value
257  * of _Hashtable::count(k) is always at most one, false if it may
258  * be an arbitrary number. This is true for unordered_set and
259  * unordered_map, false for unordered_multiset and
260  * unordered_multimap.
261  */
262  template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
263  struct _Hashtable_traits
264  {
265  using __hash_cached = __bool_constant<_Cache_hash_code>;
266  using __constant_iterators = __bool_constant<_Constant_iterators>;
267  using __unique_keys = __bool_constant<_Unique_keys>;
268  };
269 
270  /**
271  * struct _Hashtable_hash_traits
272  *
273  * Important traits for hash tables depending on associated hasher.
274  *
275  */
276  template<typename _Hash>
277  struct _Hashtable_hash_traits
278  {
279  static constexpr size_t
280  __small_size_threshold() noexcept
281  { return std::__is_fast_hash<_Hash>::value ? 0 : 20; }
282  };
283 
284  /**
285  * struct _Hash_node_base
286  *
287  * Nodes, used to wrap elements stored in the hash table. A policy
288  * template parameter of class template _Hashtable controls whether
289  * nodes also store a hash code. In some cases (e.g. strings) this
290  * may be a performance win.
291  */
292  struct _Hash_node_base
293  {
294  _Hash_node_base* _M_nxt;
295 
296  _Hash_node_base() noexcept : _M_nxt() { }
297 
298  _Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
299  };
300 
301  /**
302  * struct _Hash_node_value_base
303  *
304  * Node type with the value to store.
305  */
306  template<typename _Value>
307  struct _Hash_node_value_base
308  {
309  using value_type = _Value;
310 
311  __gnu_cxx::__aligned_buffer<_Value> _M_storage;
312 
313  // These member functions must be always_inline, see PR 111050
314 
315  [[__gnu__::__always_inline__]]
316  _Value*
317  _M_valptr() noexcept
318  { return _M_storage._M_ptr(); }
319 
320  [[__gnu__::__always_inline__]]
321  const _Value*
322  _M_valptr() const noexcept
323  { return _M_storage._M_ptr(); }
324 
325  [[__gnu__::__always_inline__]]
326  _Value&
327  _M_v() noexcept
328  { return *_M_valptr(); }
329 
330  [[__gnu__::__always_inline__]]
331  const _Value&
332  _M_v() const noexcept
333  { return *_M_valptr(); }
334  };
335 
336  /**
337  * Primary template struct _Hash_node_code_cache.
338  */
339  template<bool _Cache_hash_code>
340  struct _Hash_node_code_cache
341  { };
342 
343  /**
344  * Specialization for node with cache, struct _Hash_node_code_cache.
345  */
346  template<>
347  struct _Hash_node_code_cache<true>
348  { size_t _M_hash_code; };
349 
350  template<typename _Value, bool _Cache_hash_code>
351  struct _Hash_node_value
352  : _Hash_node_value_base<_Value>
353  , _Hash_node_code_cache<_Cache_hash_code>
354  { };
355 
356  /**
357  * Primary template struct _Hash_node.
358  */
359  template<typename _Value, bool _Cache_hash_code>
360  struct _Hash_node
361  : _Hash_node_base
362  , _Hash_node_value<_Value, _Cache_hash_code>
363  {
364  _Hash_node*
365  _M_next() const noexcept
366  { return static_cast<_Hash_node*>(this->_M_nxt); }
367  };
368 
369  /// Base class for node iterators.
370  template<typename _Value, bool _Cache_hash_code>
371  struct _Node_iterator_base
372  {
373  using __node_type = _Hash_node<_Value, _Cache_hash_code>;
374 
375  __node_type* _M_cur;
376 
377  _Node_iterator_base() : _M_cur(nullptr) { }
378  _Node_iterator_base(__node_type* __p) noexcept
379  : _M_cur(__p) { }
380 
381  void
382  _M_incr() noexcept
383  { _M_cur = _M_cur->_M_next(); }
384 
385  friend bool
386  operator==(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
387  noexcept
388  { return __x._M_cur == __y._M_cur; }
389 
390 #if __cpp_impl_three_way_comparison < 201907L
391  friend bool
392  operator!=(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
393  noexcept
394  { return __x._M_cur != __y._M_cur; }
395 #endif
396  };
397 
398  /// Node iterators, used to iterate through all the hashtable.
399  template<typename _Value, bool __constant_iterators, bool __cache>
400  struct _Node_iterator
401  : public _Node_iterator_base<_Value, __cache>
402  {
403  private:
404  using __base_type = _Node_iterator_base<_Value, __cache>;
405  using __node_type = typename __base_type::__node_type;
406 
407  public:
408  using value_type = _Value;
409  using difference_type = ptrdiff_t;
410  using iterator_category = forward_iterator_tag;
411 
412  using pointer = __conditional_t<__constant_iterators,
413  const value_type*, value_type*>;
414 
415  using reference = __conditional_t<__constant_iterators,
416  const value_type&, value_type&>;
417 
418  _Node_iterator() = default;
419 
420  explicit
421  _Node_iterator(__node_type* __p) noexcept
422  : __base_type(__p) { }
423 
424  reference
425  operator*() const noexcept
426  { return this->_M_cur->_M_v(); }
427 
428  pointer
429  operator->() const noexcept
430  { return this->_M_cur->_M_valptr(); }
431 
432  _Node_iterator&
433  operator++() noexcept
434  {
435  this->_M_incr();
436  return *this;
437  }
438 
439  _Node_iterator
440  operator++(int) noexcept
441  {
442  _Node_iterator __tmp(*this);
443  this->_M_incr();
444  return __tmp;
445  }
446 
447 #if __cpp_impl_three_way_comparison >= 201907L
448  friend bool
449  operator==(const _Node_iterator&, const _Node_iterator&) = default;
450 #else
451  friend bool
452  operator==(const _Node_iterator& __x, const _Node_iterator& __y) noexcept
453  {
454  const __base_type& __bx = __x;
455  const __base_type& __by = __y;
456  return __bx == __by;
457  }
458 
459  friend bool
460  operator!=(const _Node_iterator& __x, const _Node_iterator& __y) noexcept
461  { return !(__x == __y); }
462 #endif
463  };
464 
465  /// Node const_iterators, used to iterate through all the hashtable.
466  template<typename _Value, bool __constant_iterators, bool __cache>
467  struct _Node_const_iterator
468  : public _Node_iterator_base<_Value, __cache>
469  {
470  private:
471  using __base_type = _Node_iterator_base<_Value, __cache>;
472  using __node_type = typename __base_type::__node_type;
473 
474  // The corresponding non-const iterator.
475  using __iterator
476  = _Node_iterator<_Value, __constant_iterators, __cache>;
477 
478  public:
479  using value_type = _Value;
480  using difference_type = ptrdiff_t;
481  using iterator_category = forward_iterator_tag;
482 
483  using pointer = const value_type*;
484  using reference = const value_type&;
485 
486  _Node_const_iterator() = default;
487 
488  explicit
489  _Node_const_iterator(__node_type* __p) noexcept
490  : __base_type(__p) { }
491 
492  _Node_const_iterator(const __iterator& __x) noexcept
493  : __base_type(__x._M_cur) { }
494 
495  reference
496  operator*() const noexcept
497  { return this->_M_cur->_M_v(); }
498 
499  pointer
500  operator->() const noexcept
501  { return this->_M_cur->_M_valptr(); }
502 
503  _Node_const_iterator&
504  operator++() noexcept
505  {
506  this->_M_incr();
507  return *this;
508  }
509 
510  _Node_const_iterator
511  operator++(int) noexcept
512  {
513  _Node_const_iterator __tmp(*this);
514  this->_M_incr();
515  return __tmp;
516  }
517 
518 #if __cpp_impl_three_way_comparison >= 201907L
519  friend bool
520  operator==(const _Node_const_iterator&,
521  const _Node_const_iterator&) = default;
522 
523  friend bool
524  operator==(const _Node_const_iterator& __x, const __iterator& __y)
525  {
526  const __base_type& __bx = __x;
527  const __base_type& __by = __y;
528  return __bx == __by;
529  }
530 #else
531  friend bool
532  operator==(const _Node_const_iterator& __x,
533  const _Node_const_iterator& __y) noexcept
534  {
535  const __base_type& __bx = __x;
536  const __base_type& __by = __y;
537  return __bx == __by;
538  }
539 
540  friend bool
541  operator!=(const _Node_const_iterator& __x,
542  const _Node_const_iterator& __y) noexcept
543  { return !(__x == __y); }
544 
545  friend bool
546  operator==(const _Node_const_iterator& __x,
547  const __iterator& __y) noexcept
548  {
549  const __base_type& __bx = __x;
550  const __base_type& __by = __y;
551  return __bx == __by;
552  }
553 
554  friend bool
555  operator!=(const _Node_const_iterator& __x,
556  const __iterator& __y) noexcept
557  { return !(__x == __y); }
558 
559  friend bool
560  operator==(const __iterator& __x,
561  const _Node_const_iterator& __y) noexcept
562  {
563  const __base_type& __bx = __x;
564  const __base_type& __by = __y;
565  return __bx == __by;
566  }
567 
568  friend bool
569  operator!=(const __iterator& __x,
570  const _Node_const_iterator& __y) noexcept
571  { return !(__x == __y); }
572 #endif
573  };
574 
575  // Many of class template _Hashtable's template parameters are policy
576  // classes. These are defaults for the policies.
577 
578  /// Default range hashing function: use division to fold a large number
579  /// into the range [0, N).
580  struct _Mod_range_hashing
581  {
582  size_t
583  operator()(size_t __num, size_t __den) const noexcept
584  { return __num % __den; }
585  };
586 
587  /// Default ranged hash function H. In principle it should be a
588  /// function object composed from objects of type H1 and H2 such that
589  /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
590  /// h1 and h2. So instead we'll just use a tag to tell class template
591  /// hashtable to do that composition.
592  struct _Default_ranged_hash { };
593 
594  /// Default value for rehash policy. Bucket size is (usually) the
595  /// smallest prime that keeps the load factor small enough.
596  struct _Prime_rehash_policy
597  {
598  using __has_load_factor = true_type;
599 
600  _Prime_rehash_policy(float __z = 1.0) noexcept
601  : _M_max_load_factor(__z), _M_next_resize(0) { }
602 
603  float
604  max_load_factor() const noexcept
605  { return _M_max_load_factor; }
606 
607  // Return a bucket size no smaller than n.
608  // TODO: 'const' qualifier is kept for abi compatibility reason.
609  size_t
610  _M_next_bkt(size_t __n) const;
611 
612  // Return a bucket count appropriate for n elements
613  size_t
614  _M_bkt_for_elements(size_t __n) const
615  { return __builtin_ceil(__n / (double)_M_max_load_factor); }
616 
617  // __n_bkt is current bucket count, __n_elt is current element count,
618  // and __n_ins is number of elements to be inserted. Do we need to
619  // increase bucket count? If so, return make_pair(true, n), where n
620  // is the new bucket count. If not, return make_pair(false, 0).
621  // TODO: 'const' qualifier is kept for abi compatibility reason.
623  _M_need_rehash(size_t __n_bkt, size_t __n_elt,
624  size_t __n_ins) const;
625 
626  using _State = size_t;
627 
628  _State
629  _M_state() const
630  { return _M_next_resize; }
631 
632  void
633  _M_reset() noexcept
634  { _M_next_resize = 0; }
635 
636  void
637  _M_reset(_State __state)
638  { _M_next_resize = __state; }
639 
640  static const size_t _S_growth_factor = 2;
641 
642  float _M_max_load_factor;
643 
644  // TODO: 'mutable' kept for abi compatibility reason.
645  mutable size_t _M_next_resize;
646  };
647 
648  /// Range hashing function assuming that second arg is a power of 2.
649  struct _Mask_range_hashing
650  {
651  size_t
652  operator()(size_t __num, size_t __den) const noexcept
653  { return __num & (__den - 1); }
654  };
655 
656  /// Compute closest power of 2 not less than __n
657  inline size_t
658  __clp2(size_t __n) noexcept
659  {
661  // Equivalent to return __n ? std::bit_ceil(__n) : 0;
662  if (__n < 2)
663  return __n;
664  const unsigned __lz = sizeof(size_t) > sizeof(long)
665  ? __builtin_clzll(__n - 1ull)
666  : __builtin_clzl(__n - 1ul);
667  // Doing two shifts avoids undefined behaviour when __lz == 0.
668  return (size_t(1) << (__int_traits<size_t>::__digits - __lz - 1)) << 1;
669  }
670 
671  /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
672  /// operations.
673  struct _Power2_rehash_policy
674  {
675  using __has_load_factor = true_type;
676 
677  _Power2_rehash_policy(float __z = 1.0) noexcept
678  : _M_max_load_factor(__z), _M_next_resize(0) { }
679 
680  float
681  max_load_factor() const noexcept
682  { return _M_max_load_factor; }
683 
684  // Return a bucket size no smaller than n (as long as n is not above the
685  // highest power of 2).
686  size_t
687  _M_next_bkt(size_t __n) noexcept
688  {
689  if (__n == 0)
690  // Special case on container 1st initialization with 0 bucket count
691  // hint. We keep _M_next_resize to 0 to make sure that next time we
692  // want to add an element allocation will take place.
693  return 1;
694 
695  const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
696  const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
697  size_t __res = __clp2(__n);
698 
699  if (__res == 0)
700  __res = __max_bkt;
701  else if (__res == 1)
702  // If __res is 1 we force it to 2 to make sure there will be an
703  // allocation so that nothing need to be stored in the initial
704  // single bucket
705  __res = 2;
706 
707  if (__res == __max_bkt)
708  // Set next resize to the max value so that we never try to rehash again
709  // as we already reach the biggest possible bucket number.
710  // Note that it might result in max_load_factor not being respected.
711  _M_next_resize = size_t(-1);
712  else
713  _M_next_resize
714  = __builtin_floor(__res * (double)_M_max_load_factor);
715 
716  return __res;
717  }
718 
719  // Return a bucket count appropriate for n elements
720  size_t
721  _M_bkt_for_elements(size_t __n) const noexcept
722  { return __builtin_ceil(__n / (double)_M_max_load_factor); }
723 
724  // __n_bkt is current bucket count, __n_elt is current element count,
725  // and __n_ins is number of elements to be inserted. Do we need to
726  // increase bucket count? If so, return make_pair(true, n), where n
727  // is the new bucket count. If not, return make_pair(false, 0).
729  _M_need_rehash(size_t __n_bkt, size_t __n_elt, size_t __n_ins) noexcept
730  {
731  if (__n_elt + __n_ins > _M_next_resize)
732  {
733  // If _M_next_resize is 0 it means that we have nothing allocated so
734  // far and that we start inserting elements. In this case we start
735  // with an initial bucket size of 11.
736  double __min_bkts
737  = std::max<size_t>(__n_elt + __n_ins, _M_next_resize ? 0 : 11)
738  / (double)_M_max_load_factor;
739  if (__min_bkts >= __n_bkt)
740  return { true,
741  _M_next_bkt(std::max<size_t>(__builtin_floor(__min_bkts) + 1,
742  __n_bkt * _S_growth_factor)) };
743 
744  _M_next_resize
745  = __builtin_floor(__n_bkt * (double)_M_max_load_factor);
746  return { false, 0 };
747  }
748  else
749  return { false, 0 };
750  }
751 
752  using _State = size_t;
753 
754  _State
755  _M_state() const noexcept
756  { return _M_next_resize; }
757 
758  void
759  _M_reset() noexcept
760  { _M_next_resize = 0; }
761 
762  void
763  _M_reset(_State __state) noexcept
764  { _M_next_resize = __state; }
765 
766  static const size_t _S_growth_factor = 2;
767 
768  float _M_max_load_factor;
769  size_t _M_next_resize;
770  };
771 
772  template<typename _RehashPolicy>
773  struct _RehashStateGuard
774  {
775  _RehashPolicy* _M_guarded_obj;
776  typename _RehashPolicy::_State _M_prev_state;
777 
778  _RehashStateGuard(_RehashPolicy& __policy)
779  : _M_guarded_obj(std::__addressof(__policy))
780  , _M_prev_state(__policy._M_state())
781  { }
782  _RehashStateGuard(const _RehashStateGuard&) = delete;
783 
784  ~_RehashStateGuard()
785  {
786  if (_M_guarded_obj)
787  _M_guarded_obj->_M_reset(_M_prev_state);
788  }
789  };
790 
791  // Base classes for std::_Hashtable. We define these base classes
792  // because in some cases we want to do different things depending on
793  // the value of a policy class. In some cases the policy class
794  // affects which member functions and nested typedefs are defined;
795  // we handle that by specializing base class templates. Several of
796  // the base class templates need to access other members of class
797  // template _Hashtable, so we use a variant of the "Curiously
798  // Recurring Template Pattern" (CRTP) technique.
799 
800  /**
801  * Primary class template _Map_base.
802  *
803  * If the hashtable has a value type of the form pair<const T1, T2> and
804  * a key extraction policy (_ExtractKey) that returns the first part
805  * of the pair, the hashtable gets a mapped_type typedef. If it
806  * satisfies those criteria and also has unique keys, then it also
807  * gets an operator[].
808  */
809  template<typename _Key, typename _Value, typename _Alloc,
810  typename _ExtractKey, typename _Equal,
811  typename _Hash, typename _RangeHash, typename _Unused,
812  typename _RehashPolicy, typename _Traits,
813  bool _Unique_keys = _Traits::__unique_keys::value>
814  struct _Map_base { };
815 
816  /// Partial specialization, __unique_keys set to false, std::pair value type.
817  template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
818  typename _Hash, typename _RangeHash, typename _Unused,
819  typename _RehashPolicy, typename _Traits>
820  struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
821  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
822  {
823  using mapped_type = _Val;
824  };
825 
826  /// Partial specialization, __unique_keys set to true.
827  template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
828  typename _Hash, typename _RangeHash, typename _Unused,
829  typename _RehashPolicy, typename _Traits>
830  struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
831  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
832  {
833  private:
834  using __hashtable_base = _Hashtable_base<_Key, pair<const _Key, _Val>,
835  _Select1st, _Equal, _Hash,
836  _RangeHash, _Unused,
837  _Traits>;
838 
839  using __hashtable = _Hashtable<_Key, pair<const _Key, _Val>, _Alloc,
840  _Select1st, _Equal, _Hash, _RangeHash,
841  _Unused, _RehashPolicy, _Traits>;
842 
843  using __hash_code = typename __hashtable_base::__hash_code;
844 
845  public:
846  using key_type = typename __hashtable_base::key_type;
847  using mapped_type = _Val;
848 
849  mapped_type&
850  operator[](const key_type& __k);
851 
852  mapped_type&
853  operator[](key_type&& __k);
854 
855  // _GLIBCXX_RESOLVE_LIB_DEFECTS
856  // DR 761. unordered_map needs an at() member function.
857  mapped_type&
858  at(const key_type& __k)
859  {
860  auto __ite = static_cast<__hashtable*>(this)->find(__k);
861  if (!__ite._M_cur)
862  __throw_out_of_range(__N("unordered_map::at"));
863  return __ite->second;
864  }
865 
866  const mapped_type&
867  at(const key_type& __k) const
868  {
869  auto __ite = static_cast<const __hashtable*>(this)->find(__k);
870  if (!__ite._M_cur)
871  __throw_out_of_range(__N("unordered_map::at"));
872  return __ite->second;
873  }
874  };
875 
876  template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
877  typename _Hash, typename _RangeHash, typename _Unused,
878  typename _RehashPolicy, typename _Traits>
879  auto
880  _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
881  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
882  operator[](const key_type& __k)
883  -> mapped_type&
884  {
885  __hashtable* __h = static_cast<__hashtable*>(this);
886  __hash_code __code = __h->_M_hash_code(__k);
887  size_t __bkt = __h->_M_bucket_index(__code);
888  if (auto __node = __h->_M_find_node(__bkt, __k, __code))
889  return __node->_M_v().second;
890 
891  typename __hashtable::_Scoped_node __node {
892  __h,
895  std::tuple<>()
896  };
897  auto __pos
898  = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
899  __node._M_node = nullptr;
900  return __pos->second;
901  }
902 
903  template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
904  typename _Hash, typename _RangeHash, typename _Unused,
905  typename _RehashPolicy, typename _Traits>
906  auto
907  _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
908  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
909  operator[](key_type&& __k)
910  -> mapped_type&
911  {
912  __hashtable* __h = static_cast<__hashtable*>(this);
913  __hash_code __code = __h->_M_hash_code(__k);
914  size_t __bkt = __h->_M_bucket_index(__code);
915  if (auto __node = __h->_M_find_node(__bkt, __k, __code))
916  return __node->_M_v().second;
917 
918  typename __hashtable::_Scoped_node __node {
919  __h,
922  std::tuple<>()
923  };
924  auto __pos
925  = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
926  __node._M_node = nullptr;
927  return __pos->second;
928  }
929 
930  // Partial specialization for unordered_map<const T, U>, see PR 104174.
931  template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
932  typename _Hash, typename _RangeHash, typename _Unused,
933  typename _RehashPolicy, typename _Traits, bool __uniq>
934  struct _Map_base<const _Key, pair<const _Key, _Val>,
935  _Alloc, _Select1st, _Equal, _Hash,
936  _RangeHash, _Unused, _RehashPolicy, _Traits, __uniq>
937  : _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal, _Hash,
938  _RangeHash, _Unused, _RehashPolicy, _Traits, __uniq>
939  { };
940 
941  template<typename _Policy>
942  using __has_load_factor = typename _Policy::__has_load_factor;
943 
944  /**
945  * Primary class template _Rehash_base.
946  *
947  * Give hashtable the max_load_factor functions and reserve iff the
948  * rehash policy supports it.
949  */
950  template<typename _Key, typename _Value, typename _Alloc,
951  typename _ExtractKey, typename _Equal,
952  typename _Hash, typename _RangeHash, typename _Unused,
953  typename _RehashPolicy, typename _Traits,
954  typename =
955  __detected_or_t<false_type, __has_load_factor, _RehashPolicy>>
956  struct _Rehash_base;
957 
958  /// Specialization when rehash policy doesn't provide load factor management.
959  template<typename _Key, typename _Value, typename _Alloc,
960  typename _ExtractKey, typename _Equal,
961  typename _Hash, typename _RangeHash, typename _Unused,
962  typename _RehashPolicy, typename _Traits>
963  struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
964  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
965  false_type /* Has load factor */>
966  {
967  };
968 
969  /// Specialization when rehash policy provide load factor management.
970  template<typename _Key, typename _Value, typename _Alloc,
971  typename _ExtractKey, typename _Equal,
972  typename _Hash, typename _RangeHash, typename _Unused,
973  typename _RehashPolicy, typename _Traits>
974  struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
975  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
976  true_type /* Has load factor */>
977  {
978  private:
979  using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
980  _Equal, _Hash, _RangeHash, _Unused,
981  _RehashPolicy, _Traits>;
982 
983  public:
984  float
985  max_load_factor() const noexcept
986  {
987  const __hashtable* __this = static_cast<const __hashtable*>(this);
988  return __this->__rehash_policy().max_load_factor();
989  }
990 
991  void
992  max_load_factor(float __z)
993  {
994  __hashtable* __this = static_cast<__hashtable*>(this);
995  __this->__rehash_policy(_RehashPolicy(__z));
996  }
997 
998  void
999  reserve(size_t __n)
1000  {
1001  __hashtable* __this = static_cast<__hashtable*>(this);
1002  __this->rehash(__this->__rehash_policy()._M_bkt_for_elements(__n));
1003  }
1004  };
1005 
1006  /**
1007  * Primary class template _Hashtable_ebo_helper.
1008  *
1009  * Helper class using [[no_unique_address]] to reduce object size.
1010  */
1011  template<typename _Tp,
1012  bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
1013  struct _Hashtable_ebo_helper
1014  {
1015  [[__no_unique_address__]] _Tp _M_obj;
1016  };
1017 
1018 #if ! _GLIBCXX_INLINE_VERSION
1019  // For ABI compatibility reasons, [[no_unique_address]] is only used
1020  // for empty non-final types.
1021  template<typename _Tp>
1022  struct _Hashtable_ebo_helper<_Tp, false>
1023  {
1024  _Tp _M_obj;
1025  };
1026 #endif
1027 
1028  /**
1029  * Primary class template _Local_iterator_base.
1030  *
1031  * Base class for local iterators, used to iterate within a bucket
1032  * but not between buckets.
1033  */
1034  template<typename _Key, typename _Value, typename _ExtractKey,
1035  typename _Hash, typename _RangeHash, typename _Unused,
1036  bool __cache_hash_code>
1037  struct _Local_iterator_base;
1038 
1039  // Wraps the _Hash object and provides some utility functions for using it.
1040  template<typename _Key, typename _Value, typename _ExtractKey,
1041  typename _Hash, typename _RangeHash, typename _Unused,
1042  bool /* __cache_hash_code */>
1043  struct _Hash_code_base
1044  {
1045  // Gives the local iterator implementation access to _M_bucket_index().
1046  friend struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1047  _Hash, _RangeHash, _Unused, false>;
1048  public:
1049  using hasher = _Hash;
1050 
1051  hasher
1052  hash_function() const
1053  { return _M_hash._M_obj; }
1054 
1055  protected:
1056  [[__no_unique_address__]] _Hashtable_ebo_helper<_Hash> _M_hash{};
1057 
1058  using __hash_code = size_t;
1059 
1060  // We need the default constructor for the local iterators and _Hashtable
1061  // default constructor.
1062  _Hash_code_base() = default;
1063 
1064  _Hash_code_base(const _Hash& __hash) : _M_hash{__hash} { }
1065 
1066  __hash_code
1067  _M_hash_code(const _Key& __k) const
1068  {
1069  static_assert(__is_invocable<const _Hash&, const _Key&>{},
1070  "hash function must be invocable with an argument of key type");
1071  return _M_hash._M_obj(__k);
1072  }
1073 
1074  template<typename _Kt>
1075  __hash_code
1076  _M_hash_code_tr(const _Kt& __k) const
1077  {
1078  static_assert(__is_invocable<const _Hash&, const _Kt&>{},
1079  "hash function must be invocable with an argument of key type");
1080  return _M_hash._M_obj(__k);
1081  }
1082 
1083  __hash_code
1084  _M_hash_code(const _Hash_node_value<_Value, false>& __n) const
1085  { return _M_hash_code(_ExtractKey{}(__n._M_v())); }
1086 
1087  __hash_code
1088  _M_hash_code(const _Hash_node_value<_Value, true>& __n) const
1089  { return __n._M_hash_code; }
1090 
1091  size_t
1092  _M_bucket_index(__hash_code __c, size_t __bkt_count) const
1093  { return _RangeHash{}(__c, __bkt_count); }
1094 
1095  size_t
1096  _M_bucket_index(const _Hash_node_value<_Value, false>& __n,
1097  size_t __bkt_count) const
1098  noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>())) )
1099  {
1100  return _RangeHash{}(_M_hash_code(_ExtractKey{}(__n._M_v())),
1101  __bkt_count);
1102  }
1103 
1104  size_t
1105  _M_bucket_index(const _Hash_node_value<_Value, true>& __n,
1106  size_t __bkt_count) const noexcept
1107  { return _RangeHash{}(__n._M_hash_code, __bkt_count); }
1108  };
1109 
1110  /// Partial specialization used when nodes contain a cached hash code.
1111  template<typename _Key, typename _Value, typename _ExtractKey,
1112  typename _Hash, typename _RangeHash, typename _Unused>
1113  struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1114  _Hash, _RangeHash, _Unused, true>
1115  : public _Node_iterator_base<_Value, true>
1116  {
1117  protected:
1118  using __base_node_iter = _Node_iterator_base<_Value, true>;
1119  using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1120  _Hash, _RangeHash, _Unused, true>;
1121 
1122  _Local_iterator_base() = default;
1123 
1124  _Local_iterator_base(const __hash_code_base&,
1125  _Hash_node<_Value, true>* __p,
1126  size_t __bkt, size_t __bkt_count)
1127  : __base_node_iter(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1128  { }
1129 
1130  void
1131  _M_incr()
1132  {
1133  __base_node_iter::_M_incr();
1134  if (this->_M_cur)
1135  {
1136  size_t __bkt
1137  = _RangeHash{}(this->_M_cur->_M_hash_code, _M_bucket_count);
1138  if (__bkt != _M_bucket)
1139  this->_M_cur = nullptr;
1140  }
1141  }
1142 
1143  size_t _M_bucket = 0;
1144  size_t _M_bucket_count = 0;
1145 
1146  public:
1147  size_t
1148  _M_get_bucket() const { return _M_bucket; } // for debug mode
1149  };
1150 
1151  // Uninitialized storage for a _Hash object in a local iterator.
1152  // This type is DefaultConstructible even if the _Hash type isn't,
1153  // so that _Local_iterator_base<..., false> can be DefaultConstructible.
1154  template<typename _Hash>
1155  struct _Hash_obj_storage
1156  {
1157  union _Uninit_storage
1158  {
1159  _Uninit_storage() noexcept { }
1160  ~_Uninit_storage() { }
1161 
1162  [[__no_unique_address__]] _Hash _M_h;
1163  };
1164 
1165  [[__no_unique_address__]] _Uninit_storage _M_u;
1166  };
1167 
1168  // Partial specialization used when hash codes are not cached
1169  template<typename _Key, typename _Value, typename _ExtractKey,
1170  typename _Hash, typename _RangeHash, typename _Unused>
1171  struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1172  _Hash, _RangeHash, _Unused, false>
1173  : _Hash_obj_storage<_Hash>, _Node_iterator_base<_Value, false>
1174  {
1175  protected:
1176  using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1177  _Hash, _RangeHash, _Unused, false>;
1178  using __hash_obj_storage = _Hash_obj_storage<_Hash>;
1179  using __node_iter_base = _Node_iterator_base<_Value, false>;
1180 
1181  _Local_iterator_base() = default;
1182 
1183  _Local_iterator_base(const __hash_code_base& __base,
1184  _Hash_node<_Value, false>* __p,
1185  size_t __bkt, size_t __bkt_count)
1186  : __node_iter_base(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1187  { _M_init(__base._M_hash._M_obj); }
1188 
1189  ~_Local_iterator_base()
1190  {
1191  if (_M_bucket_count != size_t(-1))
1192  _M_destroy();
1193  }
1194 
1195  _Local_iterator_base(const _Local_iterator_base& __iter)
1196  : __node_iter_base(__iter._M_cur), _M_bucket(__iter._M_bucket)
1197  , _M_bucket_count(__iter._M_bucket_count)
1198  {
1199  if (_M_bucket_count != size_t(-1))
1200  _M_init(__iter._M_h());
1201  }
1202 
1203  _Local_iterator_base&
1204  operator=(const _Local_iterator_base& __iter)
1205  {
1206  if (_M_bucket_count != size_t(-1))
1207  _M_destroy();
1208  this->_M_cur = __iter._M_cur;
1209  _M_bucket = __iter._M_bucket;
1210  _M_bucket_count = __iter._M_bucket_count;
1211  if (_M_bucket_count != size_t(-1))
1212  _M_init(__iter._M_h());
1213  return *this;
1214  }
1215 
1216  void
1217  _M_incr()
1218  {
1219  __node_iter_base::_M_incr();
1220  if (this->_M_cur)
1221  {
1222  const auto __code = _M_h()(_ExtractKey{}(this->_M_cur->_M_v()));
1223  size_t __bkt = _RangeHash{}(__code, _M_bucket_count);
1224  if (__bkt != _M_bucket)
1225  this->_M_cur = nullptr;
1226  }
1227  }
1228 
1229  size_t _M_bucket = 0;
1230  size_t _M_bucket_count = -1;
1231 
1232  void
1233  _M_init(const _Hash& __h)
1234  { std::_Construct(std::__addressof(__hash_obj_storage::_M_u._M_h), __h); }
1235 
1236  void
1237  _M_destroy() { __hash_obj_storage::_M_u._M_h.~_Hash(); }
1238 
1239  const _Hash&
1240  _M_h() const { return __hash_obj_storage::_M_u._M_h; }
1241 
1242  public:
1243  size_t
1244  _M_get_bucket() const { return _M_bucket; } // for debug mode
1245  };
1246 
1247  /// local iterators
1248  template<typename _Key, typename _Value, typename _ExtractKey,
1249  typename _Hash, typename _RangeHash, typename _Unused,
1250  bool __constant_iterators, bool __cache>
1251  struct _Local_iterator
1252  : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1253  _Hash, _RangeHash, _Unused, __cache>
1254  {
1255  private:
1256  using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1257  _Hash, _RangeHash, _Unused, __cache>;
1258  using __hash_code_base = typename __base_type::__hash_code_base;
1259 
1260  public:
1261  using value_type = _Value;
1262  using pointer = __conditional_t<__constant_iterators,
1263  const value_type*, value_type*>;
1264  using reference = __conditional_t<__constant_iterators,
1265  const value_type&, value_type&>;
1266  using difference_type = ptrdiff_t;
1267  using iterator_category = forward_iterator_tag;
1268 
1269  _Local_iterator() = default;
1270 
1271  _Local_iterator(const __hash_code_base& __base,
1272  _Hash_node<_Value, __cache>* __n,
1273  size_t __bkt, size_t __bkt_count)
1274  : __base_type(__base, __n, __bkt, __bkt_count)
1275  { }
1276 
1277  reference
1278  operator*() const
1279  { return this->_M_cur->_M_v(); }
1280 
1281  pointer
1282  operator->() const
1283  { return this->_M_cur->_M_valptr(); }
1284 
1285  _Local_iterator&
1286  operator++()
1287  {
1288  this->_M_incr();
1289  return *this;
1290  }
1291 
1292  _Local_iterator
1293  operator++(int)
1294  {
1295  _Local_iterator __tmp(*this);
1296  this->_M_incr();
1297  return __tmp;
1298  }
1299  };
1300 
1301  /// local const_iterators
1302  template<typename _Key, typename _Value, typename _ExtractKey,
1303  typename _Hash, typename _RangeHash, typename _Unused,
1304  bool __constant_iterators, bool __cache>
1305  struct _Local_const_iterator
1306  : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1307  _Hash, _RangeHash, _Unused, __cache>
1308  {
1309  private:
1310  using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1311  _Hash, _RangeHash, _Unused, __cache>;
1312  using __hash_code_base = typename __base_type::__hash_code_base;
1313 
1314  public:
1315  using value_type = _Value;
1316  using pointer = const value_type*;
1317  using reference = const value_type&;
1318  using difference_type = ptrdiff_t;
1319  using iterator_category = forward_iterator_tag;
1320 
1321  _Local_const_iterator() = default;
1322 
1323  _Local_const_iterator(const __hash_code_base& __base,
1324  _Hash_node<_Value, __cache>* __n,
1325  size_t __bkt, size_t __bkt_count)
1326  : __base_type(__base, __n, __bkt, __bkt_count)
1327  { }
1328 
1329  _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
1330  _Hash, _RangeHash, _Unused,
1331  __constant_iterators,
1332  __cache>& __x)
1333  : __base_type(__x)
1334  { }
1335 
1336  reference
1337  operator*() const
1338  { return this->_M_cur->_M_v(); }
1339 
1340  pointer
1341  operator->() const
1342  { return this->_M_cur->_M_valptr(); }
1343 
1344  _Local_const_iterator&
1345  operator++()
1346  {
1347  this->_M_incr();
1348  return *this;
1349  }
1350 
1351  _Local_const_iterator
1352  operator++(int)
1353  {
1354  _Local_const_iterator __tmp(*this);
1355  this->_M_incr();
1356  return __tmp;
1357  }
1358  };
1359 
1360  /**
1361  * Primary class template _Hashtable_base.
1362  *
1363  * Helper class adding management of _Equal functor to
1364  * _Hash_code_base type.
1365  *
1366  * Base class templates are:
1367  * - __detail::_Hash_code_base
1368  */
1369  template<typename _Key, typename _Value, typename _ExtractKey,
1370  typename _Equal, typename _Hash, typename _RangeHash,
1371  typename _Unused, typename _Traits>
1372  struct _Hashtable_base
1373  : public _Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1374  _Unused, _Traits::__hash_cached::value>
1375  {
1376  public:
1377  using key_type = _Key;
1378  using value_type = _Value;
1379  using key_equal = _Equal;
1380  using size_type = size_t;
1381  using difference_type = ptrdiff_t;
1382 
1383  using __traits_type = _Traits;
1384  using __hash_cached = typename __traits_type::__hash_cached;
1385 
1386  using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1387  _Hash, _RangeHash, _Unused,
1388  __hash_cached::value>;
1389 
1390  using __hash_code = typename __hash_code_base::__hash_code;
1391 
1392  protected:
1393  [[__no_unique_address__]] _Hashtable_ebo_helper<_Equal> _M_equal{};
1394 
1395  _Hashtable_base() = default;
1396 
1397  _Hashtable_base(const _Hash& __hash, const _Equal& __eq)
1398  : __hash_code_base(__hash), _M_equal{__eq}
1399  { }
1400 
1401  bool
1402  _M_key_equals(const _Key& __k,
1403  const _Hash_node_value<_Value,
1404  __hash_cached::value>& __n) const
1405  {
1406  static_assert(__is_invocable<const _Equal&, const _Key&, const _Key&>{},
1407  "key equality predicate must be invocable with two arguments of "
1408  "key type");
1409  return _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1410  }
1411 
1412  template<typename _Kt>
1413  bool
1414  _M_key_equals_tr(const _Kt& __k,
1415  const _Hash_node_value<_Value,
1416  __hash_cached::value>& __n) const
1417  {
1418  static_assert(
1419  __is_invocable<const _Equal&, const _Kt&, const _Key&>{},
1420  "key equality predicate must be invocable with the argument type "
1421  "and the key type");
1422  return _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1423  }
1424 
1425 #pragma GCC diagnostic push
1426 #pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
1427  bool
1428  _M_equals(const _Key& __k, __hash_code __c,
1429  const _Hash_node_value<_Value, __hash_cached::value>& __n) const
1430  {
1431  if constexpr (__hash_cached::value)
1432  if (__c != __n._M_hash_code)
1433  return false;
1434 
1435  return _M_key_equals(__k, __n);
1436  }
1437 
1438  template<typename _Kt>
1439  bool
1440  _M_equals_tr(const _Kt& __k, __hash_code __c,
1441  const _Hash_node_value<_Value,
1442  __hash_cached::value>& __n) const
1443  {
1444  if constexpr (__hash_cached::value)
1445  if (__c != __n._M_hash_code)
1446  return false;
1447 
1448  return _M_key_equals_tr(__k, __n);
1449  }
1450 
1451  bool
1452  _M_node_equals(
1453  const _Hash_node_value<_Value, __hash_cached::value>& __lhn,
1454  const _Hash_node_value<_Value, __hash_cached::value>& __rhn) const
1455  {
1456  if constexpr (__hash_cached::value)
1457  if (__lhn._M_hash_code != __rhn._M_hash_code)
1458  return false;
1459 
1460  return _M_key_equals(_ExtractKey{}(__lhn._M_v()), __rhn);
1461  }
1462 #pragma GCC diagnostic pop
1463 
1464  const _Equal&
1465  _M_eq() const noexcept { return _M_equal._M_obj; }
1466  };
1467 
1468  /**
1469  * This type deals with all allocation and keeps an allocator instance.
1470  */
1471  template<typename _NodeAlloc>
1472  struct _Hashtable_alloc
1473  {
1474  private:
1475  [[__no_unique_address__]] _Hashtable_ebo_helper<_NodeAlloc> _M_alloc{};
1476 
1477  template<typename>
1478  struct __get_value_type;
1479  template<typename _Val, bool _Cache_hash_code>
1480  struct __get_value_type<_Hash_node<_Val, _Cache_hash_code>>
1481  { using type = _Val; };
1482 
1483  public:
1484  using __node_type = typename _NodeAlloc::value_type;
1485  using __node_alloc_type = _NodeAlloc;
1486  // Use __gnu_cxx to benefit from _S_always_equal and al.
1487  using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
1488 
1489  using __value_alloc_traits = typename __node_alloc_traits::template
1490  rebind_traits<typename __get_value_type<__node_type>::type>;
1491 
1492  using __node_ptr = __node_type*;
1493  using __node_base = _Hash_node_base;
1494  using __node_base_ptr = __node_base*;
1495  using __buckets_alloc_type =
1496  __alloc_rebind<__node_alloc_type, __node_base_ptr>;
1497  using __buckets_alloc_traits = std::allocator_traits<__buckets_alloc_type>;
1498  using __buckets_ptr = __node_base_ptr*;
1499 
1500  _Hashtable_alloc() = default;
1501  _Hashtable_alloc(const _Hashtable_alloc&) = default;
1502  _Hashtable_alloc(_Hashtable_alloc&&) = default;
1503 
1504  template<typename _Alloc>
1505  _Hashtable_alloc(_Alloc&& __a)
1506  : _M_alloc{std::forward<_Alloc>(__a)}
1507  { }
1508 
1509  __node_alloc_type&
1510  _M_node_allocator()
1511  { return _M_alloc._M_obj; }
1512 
1513  const __node_alloc_type&
1514  _M_node_allocator() const
1515  { return _M_alloc._M_obj; }
1516 
1517  // Allocate a node and construct an element within it.
1518  template<typename... _Args>
1519  __node_ptr
1520  _M_allocate_node(_Args&&... __args);
1521 
1522  // Destroy the element within a node and deallocate the node.
1523  void
1524  _M_deallocate_node(__node_ptr __n);
1525 
1526  // Deallocate a node.
1527  void
1528  _M_deallocate_node_ptr(__node_ptr __n);
1529 
1530  // Deallocate the linked list of nodes pointed to by __n.
1531  // The elements within the nodes are destroyed.
1532  void
1533  _M_deallocate_nodes(__node_ptr __n);
1534 
1535  __buckets_ptr
1536  _M_allocate_buckets(size_t __bkt_count);
1537 
1538  void
1539  _M_deallocate_buckets(__buckets_ptr, size_t __bkt_count);
1540  };
1541 
1542  // Definitions of class template _Hashtable_alloc's out-of-line member
1543  // functions.
1544  template<typename _NodeAlloc>
1545  template<typename... _Args>
1546  auto
1547  _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
1548  -> __node_ptr
1549  {
1550  auto& __alloc = _M_node_allocator();
1551  auto __nptr = __node_alloc_traits::allocate(__alloc, 1);
1552  __node_ptr __n = std::__to_address(__nptr);
1553  __try
1554  {
1555  ::new ((void*)__n) __node_type;
1556  __node_alloc_traits::construct(__alloc, __n->_M_valptr(),
1557  std::forward<_Args>(__args)...);
1558  return __n;
1559  }
1560  __catch(...)
1561  {
1562  __n->~__node_type();
1563  __node_alloc_traits::deallocate(__alloc, __nptr, 1);
1564  __throw_exception_again;
1565  }
1566  }
1567 
1568  template<typename _NodeAlloc>
1569  void
1570  _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_ptr __n)
1571  {
1572  __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
1573  _M_deallocate_node_ptr(__n);
1574  }
1575 
1576  template<typename _NodeAlloc>
1577  void
1578  _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node_ptr(__node_ptr __n)
1579  {
1580  using _Ptr = typename __node_alloc_traits::pointer;
1581  auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
1582  __n->~__node_type();
1583  __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
1584  }
1585 
1586  template<typename _NodeAlloc>
1587  void
1588  _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_ptr __n)
1589  {
1590  while (__n)
1591  {
1592  __node_ptr __tmp = __n;
1593  __n = __n->_M_next();
1594  _M_deallocate_node(__tmp);
1595  }
1596  }
1597 
1598  template<typename _NodeAlloc>
1599  auto
1600  _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(size_t __bkt_count)
1601  -> __buckets_ptr
1602  {
1603  __buckets_alloc_type __alloc(_M_node_allocator());
1604 
1605  auto __ptr = __buckets_alloc_traits::allocate(__alloc, __bkt_count);
1606  __buckets_ptr __p = std::__to_address(__ptr);
1607  __builtin_memset(__p, 0, __bkt_count * sizeof(__node_base_ptr));
1608  return __p;
1609  }
1610 
1611  template<typename _NodeAlloc>
1612  void
1613  _Hashtable_alloc<_NodeAlloc>::
1614  _M_deallocate_buckets(__buckets_ptr __bkts, size_t __bkt_count)
1615  {
1616  using _Ptr = typename __buckets_alloc_traits::pointer;
1617  auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
1618  __buckets_alloc_type __alloc(_M_node_allocator());
1619  __buckets_alloc_traits::deallocate(__alloc, __ptr, __bkt_count);
1620  }
1621 
1622  ///@} hashtable-detail
1623 } // namespace __detail
1624 /// @endcond
1625 _GLIBCXX_END_NAMESPACE_VERSION
1626 } // namespace std
1627 
1628 #endif // _HASHTABLE_POLICY_H
constexpr complex< _Tp > operator*(const complex< _Tp > &__x, const complex< _Tp > &__y)
Return new complex value x times y.
Definition: complex:434
__bool_constant< true > true_type
The type used as a compile-time boolean with true value.
Definition: type_traits:116
__bool_constant< false > false_type
The type used as a compile-time boolean with false value.
Definition: type_traits:119
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition: move.h:52
constexpr piecewise_construct_t piecewise_construct
Tag for piecewise construction of std::pair objects.
Definition: stl_pair.h:82
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:138
constexpr tuple< _Elements &&... > forward_as_tuple(_Elements &&... __args) noexcept
Create a tuple of lvalue or rvalue references to the arguments.
Definition: tuple:2678
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition: move.h:72
ISO C++ entities toplevel namespace is std.
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
constexpr void _Construct(_Tp *__p, _Args &&... __args)
__numeric_traits_integer< _Tp > __int_traits
Convenience alias for __numeric_traits<integer-type>.
constexpr _Iterator __base(_Iterator __it)
Primary class template, tuple.
Definition: tuple:834
Uniform interface to all allocator types.
Uniform interface to all pointer-like types.
Definition: ptr_traits.h:178
Struct holding two objects of arbitrary type.
Definition: stl_pair.h:304
Traits class for iterators.
Uniform interface to C++98 and C++11 allocators.