libstdc++
hashtable_policy.h
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1 // Internal policy header for unordered_set and unordered_map -*- C++ -*-
2 
3 // Copyright (C) 2010-2024 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, std::is_permutation.
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  // Helper function: return distance(first, last) for forward
66  // iterators, or 0/1 for input iterators.
67  template<typename _Iterator>
69  __distance_fw(_Iterator __first, _Iterator __last,
71  { return __first != __last ? 1 : 0; }
72 
73  template<typename _Iterator>
75  __distance_fw(_Iterator __first, _Iterator __last,
77  { return std::distance(__first, __last); }
78 
79  template<typename _Iterator>
81  __distance_fw(_Iterator __first, _Iterator __last)
82  { return __distance_fw(__first, __last,
83  std::__iterator_category(__first)); }
84 
85  struct _Identity
86  {
87  template<typename _Tp>
88  _Tp&&
89  operator()(_Tp&& __x) const noexcept
90  { return std::forward<_Tp>(__x); }
91  };
92 
93  struct _Select1st
94  {
95  template<typename _Pair>
96  struct __1st_type;
97 
98  template<typename _Tp, typename _Up>
99  struct __1st_type<pair<_Tp, _Up>>
100  { using type = _Tp; };
101 
102  template<typename _Tp, typename _Up>
103  struct __1st_type<const pair<_Tp, _Up>>
104  { using type = const _Tp; };
105 
106  template<typename _Pair>
107  struct __1st_type<_Pair&>
108  { using type = typename __1st_type<_Pair>::type&; };
109 
110  template<typename _Tp>
111  typename __1st_type<_Tp>::type&&
112  operator()(_Tp&& __x) const noexcept
113  { return std::forward<_Tp>(__x).first; }
114  };
115 
116  template<typename _ExKey, typename _Value>
117  struct _ConvertToValueType;
118 
119  template<typename _Value>
120  struct _ConvertToValueType<_Identity, _Value>
121  {
122  template<typename _Kt>
123  constexpr _Kt&&
124  operator()(_Kt&& __k) const noexcept
125  { return std::forward<_Kt>(__k); }
126  };
127 
128  template<typename _Value>
129  struct _ConvertToValueType<_Select1st, _Value>
130  {
131  constexpr _Value&&
132  operator()(_Value&& __x) const noexcept
133  { return std::move(__x); }
134 
135  constexpr const _Value&
136  operator()(const _Value& __x) const noexcept
137  { return __x; }
138 
139  template<typename _Kt, typename _Val>
140  constexpr std::pair<_Kt, _Val>&&
141  operator()(std::pair<_Kt, _Val>&& __x) const noexcept
142  { return std::move(__x); }
143 
144  template<typename _Kt, typename _Val>
145  constexpr const std::pair<_Kt, _Val>&
146  operator()(const std::pair<_Kt, _Val>& __x) const noexcept
147  { return __x; }
148  };
149 
150  template<typename _ExKey>
151  struct _NodeBuilder;
152 
153  template<>
154  struct _NodeBuilder<_Select1st>
155  {
156  template<typename _Kt, typename _Arg, typename _NodeGenerator>
157  static auto
158  _S_build(_Kt&& __k, _Arg&& __arg, const _NodeGenerator& __node_gen)
159  -> typename _NodeGenerator::__node_ptr
160  {
161  return __node_gen(std::forward<_Kt>(__k),
162  std::forward<_Arg>(__arg).second);
163  }
164  };
165 
166  template<>
167  struct _NodeBuilder<_Identity>
168  {
169  template<typename _Kt, typename _Arg, typename _NodeGenerator>
170  static auto
171  _S_build(_Kt&& __k, _Arg&&, const _NodeGenerator& __node_gen)
172  -> typename _NodeGenerator::__node_ptr
173  { return __node_gen(std::forward<_Kt>(__k)); }
174  };
175 
176  template<typename _HashtableAlloc, typename _NodePtr>
177  struct _NodePtrGuard
178  {
179  _HashtableAlloc& _M_h;
180  _NodePtr _M_ptr;
181 
182  ~_NodePtrGuard()
183  {
184  if (_M_ptr)
185  _M_h._M_deallocate_node_ptr(_M_ptr);
186  }
187  };
188 
189  template<typename _NodeAlloc>
190  struct _Hashtable_alloc;
191 
192  // Functor recycling a pool of nodes and using allocation once the pool is
193  // empty.
194  template<typename _NodeAlloc>
195  struct _ReuseOrAllocNode
196  {
197  private:
198  using __node_alloc_type = _NodeAlloc;
199  using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
200  using __node_alloc_traits =
201  typename __hashtable_alloc::__node_alloc_traits;
202 
203  public:
204  using __node_ptr = typename __hashtable_alloc::__node_ptr;
205 
206  _ReuseOrAllocNode(__node_ptr __nodes, __hashtable_alloc& __h)
207  : _M_nodes(__nodes), _M_h(__h) { }
208  _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;
209 
210  ~_ReuseOrAllocNode()
211  { _M_h._M_deallocate_nodes(_M_nodes); }
212 
213  template<typename... _Args>
214  __node_ptr
215  operator()(_Args&&... __args) const
216  {
217  if (!_M_nodes)
218  return _M_h._M_allocate_node(std::forward<_Args>(__args)...);
219 
220  __node_ptr __node = _M_nodes;
221  _M_nodes = _M_nodes->_M_next();
222  __node->_M_nxt = nullptr;
223  auto& __a = _M_h._M_node_allocator();
224  __node_alloc_traits::destroy(__a, __node->_M_valptr());
225  _NodePtrGuard<__hashtable_alloc, __node_ptr> __guard { _M_h, __node };
226  __node_alloc_traits::construct(__a, __node->_M_valptr(),
227  std::forward<_Args>(__args)...);
228  __guard._M_ptr = nullptr;
229  return __node;
230  }
231 
232  private:
233  mutable __node_ptr _M_nodes;
234  __hashtable_alloc& _M_h;
235  };
236 
237  // Functor similar to the previous one but without any pool of nodes to
238  // recycle.
239  template<typename _NodeAlloc>
240  struct _AllocNode
241  {
242  private:
243  using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
244 
245  public:
246  using __node_ptr = typename __hashtable_alloc::__node_ptr;
247 
248  _AllocNode(__hashtable_alloc& __h)
249  : _M_h(__h) { }
250 
251  template<typename... _Args>
252  __node_ptr
253  operator()(_Args&&... __args) const
254  { return _M_h._M_allocate_node(std::forward<_Args>(__args)...); }
255 
256  private:
257  __hashtable_alloc& _M_h;
258  };
259 
260  // Auxiliary types used for all instantiations of _Hashtable nodes
261  // and iterators.
262 
263  /**
264  * struct _Hashtable_traits
265  *
266  * Important traits for hash tables.
267  *
268  * @tparam _Cache_hash_code Boolean value. True if the value of
269  * the hash function is stored along with the value. This is a
270  * time-space tradeoff. Storing it may improve lookup speed by
271  * reducing the number of times we need to call the _Hash or _Equal
272  * functors.
273  *
274  * @tparam _Constant_iterators Boolean value. True if iterator and
275  * const_iterator are both constant iterator types. This is true
276  * for unordered_set and unordered_multiset, false for
277  * unordered_map and unordered_multimap.
278  *
279  * @tparam _Unique_keys Boolean value. True if the return value
280  * of _Hashtable::count(k) is always at most one, false if it may
281  * be an arbitrary number. This is true for unordered_set and
282  * unordered_map, false for unordered_multiset and
283  * unordered_multimap.
284  */
285  template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
286  struct _Hashtable_traits
287  {
288  using __hash_cached = __bool_constant<_Cache_hash_code>;
289  using __constant_iterators = __bool_constant<_Constant_iterators>;
290  using __unique_keys = __bool_constant<_Unique_keys>;
291  };
292 
293  /**
294  * struct _Hashtable_hash_traits
295  *
296  * Important traits for hash tables depending on associated hasher.
297  *
298  */
299  template<typename _Hash>
300  struct _Hashtable_hash_traits
301  {
302  static constexpr std::size_t
303  __small_size_threshold() noexcept
304  { return std::__is_fast_hash<_Hash>::value ? 0 : 20; }
305  };
306 
307  /**
308  * struct _Hash_node_base
309  *
310  * Nodes, used to wrap elements stored in the hash table. A policy
311  * template parameter of class template _Hashtable controls whether
312  * nodes also store a hash code. In some cases (e.g. strings) this
313  * may be a performance win.
314  */
315  struct _Hash_node_base
316  {
317  _Hash_node_base* _M_nxt;
318 
319  _Hash_node_base() noexcept : _M_nxt() { }
320 
321  _Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
322  };
323 
324  /**
325  * struct _Hash_node_value_base
326  *
327  * Node type with the value to store.
328  */
329  template<typename _Value>
330  struct _Hash_node_value_base
331  {
332  typedef _Value value_type;
333 
334  __gnu_cxx::__aligned_buffer<_Value> _M_storage;
335 
336  [[__gnu__::__always_inline__]]
337  _Value*
338  _M_valptr() noexcept
339  { return _M_storage._M_ptr(); }
340 
341  [[__gnu__::__always_inline__]]
342  const _Value*
343  _M_valptr() const noexcept
344  { return _M_storage._M_ptr(); }
345 
346  [[__gnu__::__always_inline__]]
347  _Value&
348  _M_v() noexcept
349  { return *_M_valptr(); }
350 
351  [[__gnu__::__always_inline__]]
352  const _Value&
353  _M_v() const noexcept
354  { return *_M_valptr(); }
355  };
356 
357  /**
358  * Primary template struct _Hash_node_code_cache.
359  */
360  template<bool _Cache_hash_code>
361  struct _Hash_node_code_cache
362  { };
363 
364  /**
365  * Specialization for node with cache, struct _Hash_node_code_cache.
366  */
367  template<>
368  struct _Hash_node_code_cache<true>
369  { std::size_t _M_hash_code; };
370 
371  template<typename _Value, bool _Cache_hash_code>
372  struct _Hash_node_value
373  : _Hash_node_value_base<_Value>
374  , _Hash_node_code_cache<_Cache_hash_code>
375  { };
376 
377  /**
378  * Primary template struct _Hash_node.
379  */
380  template<typename _Value, bool _Cache_hash_code>
381  struct _Hash_node
382  : _Hash_node_base
383  , _Hash_node_value<_Value, _Cache_hash_code>
384  {
385  _Hash_node*
386  _M_next() const noexcept
387  { return static_cast<_Hash_node*>(this->_M_nxt); }
388  };
389 
390  /// Base class for node iterators.
391  template<typename _Value, bool _Cache_hash_code>
392  struct _Node_iterator_base
393  {
394  using __node_type = _Hash_node<_Value, _Cache_hash_code>;
395 
396  __node_type* _M_cur;
397 
398  _Node_iterator_base() : _M_cur(nullptr) { }
399  _Node_iterator_base(__node_type* __p) noexcept
400  : _M_cur(__p) { }
401 
402  void
403  _M_incr() noexcept
404  { _M_cur = _M_cur->_M_next(); }
405 
406  friend bool
407  operator==(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
408  noexcept
409  { return __x._M_cur == __y._M_cur; }
410 
411 #if __cpp_impl_three_way_comparison < 201907L
412  friend bool
413  operator!=(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
414  noexcept
415  { return __x._M_cur != __y._M_cur; }
416 #endif
417  };
418 
419  /// Node iterators, used to iterate through all the hashtable.
420  template<typename _Value, bool __constant_iterators, bool __cache>
421  struct _Node_iterator
422  : public _Node_iterator_base<_Value, __cache>
423  {
424  private:
425  using __base_type = _Node_iterator_base<_Value, __cache>;
426  using __node_type = typename __base_type::__node_type;
427 
428  public:
429  using value_type = _Value;
430  using difference_type = std::ptrdiff_t;
431  using iterator_category = std::forward_iterator_tag;
432 
433  using pointer = __conditional_t<__constant_iterators,
434  const value_type*, value_type*>;
435 
436  using reference = __conditional_t<__constant_iterators,
437  const value_type&, value_type&>;
438 
439  _Node_iterator() = default;
440 
441  explicit
442  _Node_iterator(__node_type* __p) noexcept
443  : __base_type(__p) { }
444 
445  reference
446  operator*() const noexcept
447  { return this->_M_cur->_M_v(); }
448 
449  pointer
450  operator->() const noexcept
451  { return this->_M_cur->_M_valptr(); }
452 
453  _Node_iterator&
454  operator++() noexcept
455  {
456  this->_M_incr();
457  return *this;
458  }
459 
460  _Node_iterator
461  operator++(int) noexcept
462  {
463  _Node_iterator __tmp(*this);
464  this->_M_incr();
465  return __tmp;
466  }
467  };
468 
469  /// Node const_iterators, used to iterate through all the hashtable.
470  template<typename _Value, bool __constant_iterators, bool __cache>
471  struct _Node_const_iterator
472  : public _Node_iterator_base<_Value, __cache>
473  {
474  private:
475  using __base_type = _Node_iterator_base<_Value, __cache>;
476  using __node_type = typename __base_type::__node_type;
477 
478  public:
479  typedef _Value value_type;
480  typedef std::ptrdiff_t difference_type;
481  typedef std::forward_iterator_tag iterator_category;
482 
483  typedef const value_type* pointer;
484  typedef const value_type& reference;
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 _Node_iterator<_Value, __constant_iterators,
493  __cache>& __x) noexcept
494  : __base_type(__x._M_cur) { }
495 
496  reference
497  operator*() const noexcept
498  { return this->_M_cur->_M_v(); }
499 
500  pointer
501  operator->() const noexcept
502  { return this->_M_cur->_M_valptr(); }
503 
504  _Node_const_iterator&
505  operator++() noexcept
506  {
507  this->_M_incr();
508  return *this;
509  }
510 
511  _Node_const_iterator
512  operator++(int) noexcept
513  {
514  _Node_const_iterator __tmp(*this);
515  this->_M_incr();
516  return __tmp;
517  }
518  };
519 
520  // Many of class template _Hashtable's template parameters are policy
521  // classes. These are defaults for the policies.
522 
523  /// Default range hashing function: use division to fold a large number
524  /// into the range [0, N).
525  struct _Mod_range_hashing
526  {
527  typedef std::size_t first_argument_type;
528  typedef std::size_t second_argument_type;
529  typedef std::size_t result_type;
530 
531  result_type
532  operator()(first_argument_type __num,
533  second_argument_type __den) const noexcept
534  { return __num % __den; }
535  };
536 
537  /// Default ranged hash function H. In principle it should be a
538  /// function object composed from objects of type H1 and H2 such that
539  /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
540  /// h1 and h2. So instead we'll just use a tag to tell class template
541  /// hashtable to do that composition.
542  struct _Default_ranged_hash { };
543 
544  /// Default value for rehash policy. Bucket size is (usually) the
545  /// smallest prime that keeps the load factor small enough.
546  struct _Prime_rehash_policy
547  {
548  using __has_load_factor = true_type;
549 
550  _Prime_rehash_policy(float __z = 1.0) noexcept
551  : _M_max_load_factor(__z), _M_next_resize(0) { }
552 
553  float
554  max_load_factor() const noexcept
555  { return _M_max_load_factor; }
556 
557  // Return a bucket size no smaller than n.
558  std::size_t
559  _M_next_bkt(std::size_t __n) const;
560 
561  // Return a bucket count appropriate for n elements
562  std::size_t
563  _M_bkt_for_elements(std::size_t __n) const
564  { return __builtin_ceil(__n / (double)_M_max_load_factor); }
565 
566  // __n_bkt is current bucket count, __n_elt is current element count,
567  // and __n_ins is number of elements to be inserted. Do we need to
568  // increase bucket count? If so, return make_pair(true, n), where n
569  // is the new bucket count. If not, return make_pair(false, 0).
571  _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
572  std::size_t __n_ins) const;
573 
574  typedef std::size_t _State;
575 
576  _State
577  _M_state() const
578  { return _M_next_resize; }
579 
580  void
581  _M_reset() noexcept
582  { _M_next_resize = 0; }
583 
584  void
585  _M_reset(_State __state)
586  { _M_next_resize = __state; }
587 
588  static const std::size_t _S_growth_factor = 2;
589 
590  float _M_max_load_factor;
591  mutable std::size_t _M_next_resize;
592  };
593 
594  /// Range hashing function assuming that second arg is a power of 2.
595  struct _Mask_range_hashing
596  {
597  typedef std::size_t first_argument_type;
598  typedef std::size_t second_argument_type;
599  typedef std::size_t result_type;
600 
601  result_type
602  operator()(first_argument_type __num,
603  second_argument_type __den) const noexcept
604  { return __num & (__den - 1); }
605  };
606 
607  /// Compute closest power of 2 not less than __n
608  inline std::size_t
609  __clp2(std::size_t __n) noexcept
610  {
612  // Equivalent to return __n ? std::bit_ceil(__n) : 0;
613  if (__n < 2)
614  return __n;
615  const unsigned __lz = sizeof(size_t) > sizeof(long)
616  ? __builtin_clzll(__n - 1ull)
617  : __builtin_clzl(__n - 1ul);
618  // Doing two shifts avoids undefined behaviour when __lz == 0.
619  return (size_t(1) << (__int_traits<size_t>::__digits - __lz - 1)) << 1;
620  }
621 
622  /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
623  /// operations.
624  struct _Power2_rehash_policy
625  {
626  using __has_load_factor = true_type;
627 
628  _Power2_rehash_policy(float __z = 1.0) noexcept
629  : _M_max_load_factor(__z), _M_next_resize(0) { }
630 
631  float
632  max_load_factor() const noexcept
633  { return _M_max_load_factor; }
634 
635  // Return a bucket size no smaller than n (as long as n is not above the
636  // highest power of 2).
637  std::size_t
638  _M_next_bkt(std::size_t __n) noexcept
639  {
640  if (__n == 0)
641  // Special case on container 1st initialization with 0 bucket count
642  // hint. We keep _M_next_resize to 0 to make sure that next time we
643  // want to add an element allocation will take place.
644  return 1;
645 
646  const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
647  const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
648  std::size_t __res = __clp2(__n);
649 
650  if (__res == 0)
651  __res = __max_bkt;
652  else if (__res == 1)
653  // If __res is 1 we force it to 2 to make sure there will be an
654  // allocation so that nothing need to be stored in the initial
655  // single bucket
656  __res = 2;
657 
658  if (__res == __max_bkt)
659  // Set next resize to the max value so that we never try to rehash again
660  // as we already reach the biggest possible bucket number.
661  // Note that it might result in max_load_factor not being respected.
662  _M_next_resize = size_t(-1);
663  else
664  _M_next_resize
665  = __builtin_floor(__res * (double)_M_max_load_factor);
666 
667  return __res;
668  }
669 
670  // Return a bucket count appropriate for n elements
671  std::size_t
672  _M_bkt_for_elements(std::size_t __n) const noexcept
673  { return __builtin_ceil(__n / (double)_M_max_load_factor); }
674 
675  // __n_bkt is current bucket count, __n_elt is current element count,
676  // and __n_ins is number of elements to be inserted. Do we need to
677  // increase bucket count? If so, return make_pair(true, n), where n
678  // is the new bucket count. If not, return make_pair(false, 0).
680  _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
681  std::size_t __n_ins) noexcept
682  {
683  if (__n_elt + __n_ins > _M_next_resize)
684  {
685  // If _M_next_resize is 0 it means that we have nothing allocated so
686  // far and that we start inserting elements. In this case we start
687  // with an initial bucket size of 11.
688  double __min_bkts
689  = std::max<std::size_t>(__n_elt + __n_ins, _M_next_resize ? 0 : 11)
690  / (double)_M_max_load_factor;
691  if (__min_bkts >= __n_bkt)
692  return { true,
693  _M_next_bkt(std::max<std::size_t>(__builtin_floor(__min_bkts) + 1,
694  __n_bkt * _S_growth_factor)) };
695 
696  _M_next_resize
697  = __builtin_floor(__n_bkt * (double)_M_max_load_factor);
698  return { false, 0 };
699  }
700  else
701  return { false, 0 };
702  }
703 
704  typedef std::size_t _State;
705 
706  _State
707  _M_state() const noexcept
708  { return _M_next_resize; }
709 
710  void
711  _M_reset() noexcept
712  { _M_next_resize = 0; }
713 
714  void
715  _M_reset(_State __state) noexcept
716  { _M_next_resize = __state; }
717 
718  static const std::size_t _S_growth_factor = 2;
719 
720  float _M_max_load_factor;
721  std::size_t _M_next_resize;
722  };
723 
724  template<typename _RehashPolicy>
725  struct _RehashStateGuard
726  {
727  _RehashPolicy* _M_guarded_obj;
728  typename _RehashPolicy::_State _M_prev_state;
729 
730  _RehashStateGuard(_RehashPolicy& __policy)
731  : _M_guarded_obj(std::__addressof(__policy))
732  , _M_prev_state(__policy._M_state())
733  { }
734  _RehashStateGuard(const _RehashStateGuard&) = delete;
735 
736  ~_RehashStateGuard()
737  {
738  if (_M_guarded_obj)
739  _M_guarded_obj->_M_reset(_M_prev_state);
740  }
741  };
742 
743  // Base classes for std::_Hashtable. We define these base classes
744  // because in some cases we want to do different things depending on
745  // the value of a policy class. In some cases the policy class
746  // affects which member functions and nested typedefs are defined;
747  // we handle that by specializing base class templates. Several of
748  // the base class templates need to access other members of class
749  // template _Hashtable, so we use a variant of the "Curiously
750  // Recurring Template Pattern" (CRTP) technique.
751 
752  /**
753  * Primary class template _Map_base.
754  *
755  * If the hashtable has a value type of the form pair<const T1, T2> and
756  * a key extraction policy (_ExtractKey) that returns the first part
757  * of the pair, the hashtable gets a mapped_type typedef. If it
758  * satisfies those criteria and also has unique keys, then it also
759  * gets an operator[].
760  */
761  template<typename _Key, typename _Value, typename _Alloc,
762  typename _ExtractKey, typename _Equal,
763  typename _Hash, typename _RangeHash, typename _Unused,
764  typename _RehashPolicy, typename _Traits,
765  bool _Unique_keys = _Traits::__unique_keys::value>
766  struct _Map_base { };
767 
768  /// Partial specialization, __unique_keys set to false, std::pair value type.
769  template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
770  typename _Hash, typename _RangeHash, typename _Unused,
771  typename _RehashPolicy, typename _Traits>
772  struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
773  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
774  {
775  using mapped_type = _Val;
776  };
777 
778  /// Partial specialization, __unique_keys set to true.
779  template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
780  typename _Hash, typename _RangeHash, typename _Unused,
781  typename _RehashPolicy, typename _Traits>
782  struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
783  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
784  {
785  private:
786  using __hashtable_base = _Hashtable_base<_Key, pair<const _Key, _Val>,
787  _Select1st, _Equal, _Hash,
788  _RangeHash, _Unused,
789  _Traits>;
790 
791  using __hashtable = _Hashtable<_Key, pair<const _Key, _Val>, _Alloc,
792  _Select1st, _Equal, _Hash, _RangeHash,
793  _Unused, _RehashPolicy, _Traits>;
794 
795  using __hash_code = typename __hashtable_base::__hash_code;
796 
797  public:
798  using key_type = typename __hashtable_base::key_type;
799  using mapped_type = _Val;
800 
801  mapped_type&
802  operator[](const key_type& __k);
803 
804  mapped_type&
805  operator[](key_type&& __k);
806 
807  // _GLIBCXX_RESOLVE_LIB_DEFECTS
808  // DR 761. unordered_map needs an at() member function.
809  mapped_type&
810  at(const key_type& __k)
811  {
812  auto __ite = static_cast<__hashtable*>(this)->find(__k);
813  if (!__ite._M_cur)
814  __throw_out_of_range(__N("unordered_map::at"));
815  return __ite->second;
816  }
817 
818  const mapped_type&
819  at(const key_type& __k) const
820  {
821  auto __ite = static_cast<const __hashtable*>(this)->find(__k);
822  if (!__ite._M_cur)
823  __throw_out_of_range(__N("unordered_map::at"));
824  return __ite->second;
825  }
826  };
827 
828  template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
829  typename _Hash, typename _RangeHash, typename _Unused,
830  typename _RehashPolicy, typename _Traits>
831  auto
832  _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
833  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
834  operator[](const key_type& __k)
835  -> mapped_type&
836  {
837  __hashtable* __h = static_cast<__hashtable*>(this);
838  __hash_code __code = __h->_M_hash_code(__k);
839  std::size_t __bkt = __h->_M_bucket_index(__code);
840  if (auto __node = __h->_M_find_node(__bkt, __k, __code))
841  return __node->_M_v().second;
842 
843  typename __hashtable::_Scoped_node __node {
844  __h,
847  std::tuple<>()
848  };
849  auto __pos
850  = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
851  __node._M_node = nullptr;
852  return __pos->second;
853  }
854 
855  template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
856  typename _Hash, typename _RangeHash, typename _Unused,
857  typename _RehashPolicy, typename _Traits>
858  auto
859  _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal,
860  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
861  operator[](key_type&& __k)
862  -> mapped_type&
863  {
864  __hashtable* __h = static_cast<__hashtable*>(this);
865  __hash_code __code = __h->_M_hash_code(__k);
866  std::size_t __bkt = __h->_M_bucket_index(__code);
867  if (auto __node = __h->_M_find_node(__bkt, __k, __code))
868  return __node->_M_v().second;
869 
870  typename __hashtable::_Scoped_node __node {
871  __h,
874  std::tuple<>()
875  };
876  auto __pos
877  = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
878  __node._M_node = nullptr;
879  return __pos->second;
880  }
881 
882  // Partial specialization for unordered_map<const T, U>, see PR 104174.
883  template<typename _Key, typename _Val, typename _Alloc, typename _Equal,
884  typename _Hash, typename _RangeHash, typename _Unused,
885  typename _RehashPolicy, typename _Traits, bool __uniq>
886  struct _Map_base<const _Key, pair<const _Key, _Val>,
887  _Alloc, _Select1st, _Equal, _Hash,
888  _RangeHash, _Unused, _RehashPolicy, _Traits, __uniq>
889  : _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal, _Hash,
890  _RangeHash, _Unused, _RehashPolicy, _Traits, __uniq>
891  { };
892 
893  /**
894  * Primary class template _Insert_base.
895  *
896  * Defines @c insert member functions appropriate to all _Hashtables.
897  */
898  template<typename _Key, typename _Value, typename _Alloc,
899  typename _ExtractKey, typename _Equal,
900  typename _Hash, typename _RangeHash, typename _Unused,
901  typename _RehashPolicy, typename _Traits>
902  struct _Insert_base
903  {
904  protected:
905  using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
906  _Equal, _Hash, _RangeHash,
907  _Unused, _Traits>;
908 
909  using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
910  _Hash, _RangeHash,
911  _Unused, _RehashPolicy, _Traits>;
912 
913  using __hash_cached = typename _Traits::__hash_cached;
914  using __constant_iterators = typename _Traits::__constant_iterators;
915 
916  using __hashtable_alloc = _Hashtable_alloc<
917  __alloc_rebind<_Alloc, _Hash_node<_Value,
918  __hash_cached::value>>>;
919 
920  using value_type = typename __hashtable_base::value_type;
921  using size_type = typename __hashtable_base::size_type;
922 
923  using __unique_keys = typename _Traits::__unique_keys;
924  using __node_alloc_type = typename __hashtable_alloc::__node_alloc_type;
925  using __node_gen_type = _AllocNode<__node_alloc_type>;
926 
927  __hashtable&
928  _M_conjure_hashtable()
929  { return *(static_cast<__hashtable*>(this)); }
930 
931  template<typename _InputIterator, typename _NodeGetter>
932  void
933  _M_insert_range(_InputIterator __first, _InputIterator __last,
934  const _NodeGetter&, true_type __uks);
935 
936  template<typename _InputIterator, typename _NodeGetter>
937  void
938  _M_insert_range(_InputIterator __first, _InputIterator __last,
939  const _NodeGetter&, false_type __uks);
940 
941  public:
942  using iterator = _Node_iterator<_Value, __constant_iterators::value,
943  __hash_cached::value>;
944 
945  using const_iterator = _Node_const_iterator<_Value,
946  __constant_iterators::value,
947  __hash_cached::value>;
948 
949  using __ireturn_type = __conditional_t<__unique_keys::value,
951  iterator>;
952 
953  __ireturn_type
954  insert(const value_type& __v)
955  {
956  __hashtable& __h = _M_conjure_hashtable();
957  __node_gen_type __node_gen(__h);
958  return __h._M_insert(__v, __node_gen, __unique_keys{});
959  }
960 
961  iterator
962  insert(const_iterator __hint, const value_type& __v)
963  {
964  __hashtable& __h = _M_conjure_hashtable();
965  __node_gen_type __node_gen(__h);
966  return __h._M_insert(__hint, __v, __node_gen, __unique_keys{});
967  }
968 
969  template<typename _KType, typename... _Args>
971  try_emplace(const_iterator, _KType&& __k, _Args&&... __args)
972  {
973  __hashtable& __h = _M_conjure_hashtable();
974  auto __code = __h._M_hash_code(__k);
975  std::size_t __bkt = __h._M_bucket_index(__code);
976  if (auto __node = __h._M_find_node(__bkt, __k, __code))
977  return { iterator(__node), false };
978 
979  typename __hashtable::_Scoped_node __node {
980  &__h,
982  std::forward_as_tuple(std::forward<_KType>(__k)),
983  std::forward_as_tuple(std::forward<_Args>(__args)...)
984  };
985  auto __it
986  = __h._M_insert_unique_node(__bkt, __code, __node._M_node);
987  __node._M_node = nullptr;
988  return { __it, true };
989  }
990 
991  void
992  insert(initializer_list<value_type> __l)
993  { this->insert(__l.begin(), __l.end()); }
994 
995  template<typename _InputIterator>
996  void
997  insert(_InputIterator __first, _InputIterator __last)
998  {
999  __hashtable& __h = _M_conjure_hashtable();
1000  __node_gen_type __node_gen(__h);
1001  return _M_insert_range(__first, __last, __node_gen, __unique_keys{});
1002  }
1003  };
1004 
1005  template<typename _Key, typename _Value, typename _Alloc,
1006  typename _ExtractKey, typename _Equal,
1007  typename _Hash, typename _RangeHash, typename _Unused,
1008  typename _RehashPolicy, typename _Traits>
1009  template<typename _InputIterator, typename _NodeGetter>
1010  void
1011  _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1012  _Hash, _RangeHash, _Unused,
1013  _RehashPolicy, _Traits>::
1014  _M_insert_range(_InputIterator __first, _InputIterator __last,
1015  const _NodeGetter& __node_gen, true_type __uks)
1016  {
1017  __hashtable& __h = _M_conjure_hashtable();
1018  for (; __first != __last; ++__first)
1019  __h._M_insert(*__first, __node_gen, __uks);
1020  }
1021 
1022  template<typename _Key, typename _Value, typename _Alloc,
1023  typename _ExtractKey, typename _Equal,
1024  typename _Hash, typename _RangeHash, typename _Unused,
1025  typename _RehashPolicy, typename _Traits>
1026  template<typename _InputIterator, typename _NodeGetter>
1027  void
1028  _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1029  _Hash, _RangeHash, _Unused,
1030  _RehashPolicy, _Traits>::
1031  _M_insert_range(_InputIterator __first, _InputIterator __last,
1032  const _NodeGetter& __node_gen, false_type __uks)
1033  {
1034  using __rehash_guard_t = typename __hashtable::__rehash_guard_t;
1035  using __pair_type = std::pair<bool, std::size_t>;
1036 
1037  size_type __n_elt = __detail::__distance_fw(__first, __last);
1038  if (__n_elt == 0)
1039  return;
1040 
1041  __hashtable& __h = _M_conjure_hashtable();
1042  __rehash_guard_t __rehash_guard(__h._M_rehash_policy);
1043  __pair_type __do_rehash
1044  = __h._M_rehash_policy._M_need_rehash(__h._M_bucket_count,
1045  __h._M_element_count,
1046  __n_elt);
1047 
1048  if (__do_rehash.first)
1049  __h._M_rehash(__do_rehash.second, __uks);
1050 
1051  __rehash_guard._M_guarded_obj = nullptr;
1052  for (; __first != __last; ++__first)
1053  __h._M_insert(*__first, __node_gen, __uks);
1054  }
1055 
1056  /**
1057  * Primary class template _Insert.
1058  *
1059  * Defines @c insert member functions that depend on _Hashtable policies,
1060  * via partial specializations.
1061  */
1062  template<typename _Key, typename _Value, typename _Alloc,
1063  typename _ExtractKey, typename _Equal,
1064  typename _Hash, typename _RangeHash, typename _Unused,
1065  typename _RehashPolicy, typename _Traits,
1066  bool _Constant_iterators = _Traits::__constant_iterators::value>
1067  struct _Insert;
1068 
1069  /// Specialization.
1070  template<typename _Key, typename _Value, typename _Alloc,
1071  typename _ExtractKey, typename _Equal,
1072  typename _Hash, typename _RangeHash, typename _Unused,
1073  typename _RehashPolicy, typename _Traits>
1074  struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1075  _Hash, _RangeHash, _Unused,
1076  _RehashPolicy, _Traits, true>
1077  : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1078  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>
1079  {
1080  using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
1081  _Equal, _Hash, _RangeHash, _Unused,
1082  _RehashPolicy, _Traits>;
1083 
1084  using value_type = typename __base_type::value_type;
1085  using iterator = typename __base_type::iterator;
1086  using const_iterator = typename __base_type::const_iterator;
1087  using __ireturn_type = typename __base_type::__ireturn_type;
1088 
1089  using __unique_keys = typename __base_type::__unique_keys;
1090  using __hashtable = typename __base_type::__hashtable;
1091  using __node_gen_type = typename __base_type::__node_gen_type;
1092 
1093  using __base_type::insert;
1094 
1095  __ireturn_type
1096  insert(value_type&& __v)
1097  {
1098  __hashtable& __h = this->_M_conjure_hashtable();
1099  __node_gen_type __node_gen(__h);
1100  return __h._M_insert(std::move(__v), __node_gen, __unique_keys{});
1101  }
1102 
1103  iterator
1104  insert(const_iterator __hint, value_type&& __v)
1105  {
1106  __hashtable& __h = this->_M_conjure_hashtable();
1107  __node_gen_type __node_gen(__h);
1108  return __h._M_insert(__hint, std::move(__v), __node_gen,
1109  __unique_keys{});
1110  }
1111  };
1112 
1113  /// Specialization.
1114  template<typename _Key, typename _Value, typename _Alloc,
1115  typename _ExtractKey, typename _Equal,
1116  typename _Hash, typename _RangeHash, typename _Unused,
1117  typename _RehashPolicy, typename _Traits>
1118  struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1119  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
1120  : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1121  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>
1122  {
1123  using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
1124  _Equal, _Hash, _RangeHash, _Unused,
1125  _RehashPolicy, _Traits>;
1126  using value_type = typename __base_type::value_type;
1127  using iterator = typename __base_type::iterator;
1128  using const_iterator = typename __base_type::const_iterator;
1129 
1130  using __unique_keys = typename __base_type::__unique_keys;
1131  using __hashtable = typename __base_type::__hashtable;
1132  using __ireturn_type = typename __base_type::__ireturn_type;
1133 
1134  using __base_type::insert;
1135 
1136  template<typename _Pair>
1138 
1139  template<typename _Pair>
1140  using _IFcons = std::enable_if<__is_cons<_Pair>::value>;
1141 
1142  template<typename _Pair>
1143  using _IFconsp = typename _IFcons<_Pair>::type;
1144 
1145  template<typename _Pair, typename = _IFconsp<_Pair>>
1146  __ireturn_type
1147  insert(_Pair&& __v)
1148  {
1149  __hashtable& __h = this->_M_conjure_hashtable();
1150  return __h._M_emplace(__unique_keys{}, std::forward<_Pair>(__v));
1151  }
1152 
1153  template<typename _Pair, typename = _IFconsp<_Pair>>
1154  iterator
1155  insert(const_iterator __hint, _Pair&& __v)
1156  {
1157  __hashtable& __h = this->_M_conjure_hashtable();
1158  return __h._M_emplace(__hint, __unique_keys{},
1159  std::forward<_Pair>(__v));
1160  }
1161  };
1162 
1163  template<typename _Policy>
1164  using __has_load_factor = typename _Policy::__has_load_factor;
1165 
1166  /**
1167  * Primary class template _Rehash_base.
1168  *
1169  * Give hashtable the max_load_factor functions and reserve iff the
1170  * rehash policy supports it.
1171  */
1172  template<typename _Key, typename _Value, typename _Alloc,
1173  typename _ExtractKey, typename _Equal,
1174  typename _Hash, typename _RangeHash, typename _Unused,
1175  typename _RehashPolicy, typename _Traits,
1176  typename =
1177  __detected_or_t<false_type, __has_load_factor, _RehashPolicy>>
1178  struct _Rehash_base;
1179 
1180  /// Specialization when rehash policy doesn't provide load factor management.
1181  template<typename _Key, typename _Value, typename _Alloc,
1182  typename _ExtractKey, typename _Equal,
1183  typename _Hash, typename _RangeHash, typename _Unused,
1184  typename _RehashPolicy, typename _Traits>
1185  struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1186  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
1187  false_type /* Has load factor */>
1188  {
1189  };
1190 
1191  /// Specialization when rehash policy provide load factor management.
1192  template<typename _Key, typename _Value, typename _Alloc,
1193  typename _ExtractKey, typename _Equal,
1194  typename _Hash, typename _RangeHash, typename _Unused,
1195  typename _RehashPolicy, typename _Traits>
1196  struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1197  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
1198  true_type /* Has load factor */>
1199  {
1200  private:
1201  using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
1202  _Equal, _Hash, _RangeHash, _Unused,
1203  _RehashPolicy, _Traits>;
1204 
1205  public:
1206  float
1207  max_load_factor() const noexcept
1208  {
1209  const __hashtable* __this = static_cast<const __hashtable*>(this);
1210  return __this->__rehash_policy().max_load_factor();
1211  }
1212 
1213  void
1214  max_load_factor(float __z)
1215  {
1216  __hashtable* __this = static_cast<__hashtable*>(this);
1217  __this->__rehash_policy(_RehashPolicy(__z));
1218  }
1219 
1220  void
1221  reserve(std::size_t __n)
1222  {
1223  __hashtable* __this = static_cast<__hashtable*>(this);
1224  __this->rehash(__this->__rehash_policy()._M_bkt_for_elements(__n));
1225  }
1226  };
1227 
1228  /**
1229  * Primary class template _Hashtable_ebo_helper.
1230  *
1231  * Helper class using EBO when it is not forbidden (the type is not
1232  * final) and when it is worth it (the type is empty.)
1233  */
1234  template<int _Nm, typename _Tp,
1235  bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
1236  struct _Hashtable_ebo_helper;
1237 
1238  /// Specialization using EBO.
1239  template<int _Nm, typename _Tp>
1240  struct _Hashtable_ebo_helper<_Nm, _Tp, true>
1241  : private _Tp
1242  {
1243  _Hashtable_ebo_helper() noexcept(noexcept(_Tp())) : _Tp() { }
1244 
1245  template<typename _OtherTp>
1246  _Hashtable_ebo_helper(_OtherTp&& __tp)
1247  : _Tp(std::forward<_OtherTp>(__tp))
1248  { }
1249 
1250  const _Tp& _M_cget() const { return static_cast<const _Tp&>(*this); }
1251  _Tp& _M_get() { return static_cast<_Tp&>(*this); }
1252  };
1253 
1254  /// Specialization not using EBO.
1255  template<int _Nm, typename _Tp>
1256  struct _Hashtable_ebo_helper<_Nm, _Tp, false>
1257  {
1258  _Hashtable_ebo_helper() = default;
1259 
1260  template<typename _OtherTp>
1261  _Hashtable_ebo_helper(_OtherTp&& __tp)
1262  : _M_tp(std::forward<_OtherTp>(__tp))
1263  { }
1264 
1265  const _Tp& _M_cget() const { return _M_tp; }
1266  _Tp& _M_get() { return _M_tp; }
1267 
1268  private:
1269  _Tp _M_tp{};
1270  };
1271 
1272  /**
1273  * Primary class template _Local_iterator_base.
1274  *
1275  * Base class for local iterators, used to iterate within a bucket
1276  * but not between buckets.
1277  */
1278  template<typename _Key, typename _Value, typename _ExtractKey,
1279  typename _Hash, typename _RangeHash, typename _Unused,
1280  bool __cache_hash_code>
1281  struct _Local_iterator_base;
1282 
1283  /**
1284  * Primary class template _Hash_code_base.
1285  *
1286  * Encapsulates two policy issues that aren't quite orthogonal.
1287  * (1) the difference between using a ranged hash function and using
1288  * the combination of a hash function and a range-hashing function.
1289  * In the former case we don't have such things as hash codes, so
1290  * we have a dummy type as placeholder.
1291  * (2) Whether or not we cache hash codes. Caching hash codes is
1292  * meaningless if we have a ranged hash function.
1293  *
1294  * We also put the key extraction objects here, for convenience.
1295  * Each specialization derives from one or more of the template
1296  * parameters to benefit from Ebo. This is important as this type
1297  * is inherited in some cases by the _Local_iterator_base type used
1298  * to implement local_iterator and const_local_iterator. As with
1299  * any iterator type we prefer to make it as small as possible.
1300  */
1301  template<typename _Key, typename _Value, typename _ExtractKey,
1302  typename _Hash, typename _RangeHash, typename _Unused,
1303  bool __cache_hash_code>
1304  struct _Hash_code_base
1305  : private _Hashtable_ebo_helper<1, _Hash>
1306  {
1307  private:
1308  using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>;
1309 
1310  // Gives the local iterator implementation access to _M_bucket_index().
1311  friend struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1312  _Hash, _RangeHash, _Unused, false>;
1313 
1314  public:
1315  typedef _Hash hasher;
1316 
1317  hasher
1318  hash_function() const
1319  { return _M_hash(); }
1320 
1321  protected:
1322  typedef std::size_t __hash_code;
1323 
1324  // We need the default constructor for the local iterators and _Hashtable
1325  // default constructor.
1326  _Hash_code_base() = default;
1327 
1328  _Hash_code_base(const _Hash& __hash) : __ebo_hash(__hash) { }
1329 
1330  __hash_code
1331  _M_hash_code(const _Key& __k) const
1332  {
1333  static_assert(__is_invocable<const _Hash&, const _Key&>{},
1334  "hash function must be invocable with an argument of key type");
1335  return _M_hash()(__k);
1336  }
1337 
1338  template<typename _Kt>
1339  __hash_code
1340  _M_hash_code_tr(const _Kt& __k) const
1341  {
1342  static_assert(__is_invocable<const _Hash&, const _Kt&>{},
1343  "hash function must be invocable with an argument of key type");
1344  return _M_hash()(__k);
1345  }
1346 
1347  __hash_code
1348  _M_hash_code(const _Hash_node_value<_Value, false>& __n) const
1349  { return _M_hash_code(_ExtractKey{}(__n._M_v())); }
1350 
1351  __hash_code
1352  _M_hash_code(const _Hash_node_value<_Value, true>& __n) const
1353  { return __n._M_hash_code; }
1354 
1355  std::size_t
1356  _M_bucket_index(__hash_code __c, std::size_t __bkt_count) const
1357  { return _RangeHash{}(__c, __bkt_count); }
1358 
1359  std::size_t
1360  _M_bucket_index(const _Hash_node_value<_Value, false>& __n,
1361  std::size_t __bkt_count) const
1362  noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>()))
1363  && noexcept(declval<const _RangeHash&>()((__hash_code)0,
1364  (std::size_t)0)) )
1365  {
1366  return _RangeHash{}(_M_hash_code(_ExtractKey{}(__n._M_v())),
1367  __bkt_count);
1368  }
1369 
1370  std::size_t
1371  _M_bucket_index(const _Hash_node_value<_Value, true>& __n,
1372  std::size_t __bkt_count) const
1373  noexcept( noexcept(declval<const _RangeHash&>()((__hash_code)0,
1374  (std::size_t)0)) )
1375  { return _RangeHash{}(__n._M_hash_code, __bkt_count); }
1376 
1377  void
1378  _M_store_code(_Hash_node_code_cache<false>&, __hash_code) const
1379  { }
1380 
1381  void
1382  _M_copy_code(_Hash_node_code_cache<false>&,
1383  const _Hash_node_code_cache<false>&) const
1384  { }
1385 
1386  void
1387  _M_store_code(_Hash_node_code_cache<true>& __n, __hash_code __c) const
1388  { __n._M_hash_code = __c; }
1389 
1390  void
1391  _M_copy_code(_Hash_node_code_cache<true>& __to,
1392  const _Hash_node_code_cache<true>& __from) const
1393  { __to._M_hash_code = __from._M_hash_code; }
1394 
1395  void
1396  _M_swap(_Hash_code_base& __x)
1397  { std::swap(__ebo_hash::_M_get(), __x.__ebo_hash::_M_get()); }
1398 
1399  const _Hash&
1400  _M_hash() const { return __ebo_hash::_M_cget(); }
1401  };
1402 
1403  /// Partial specialization used when nodes contain a cached hash code.
1404  template<typename _Key, typename _Value, typename _ExtractKey,
1405  typename _Hash, typename _RangeHash, typename _Unused>
1406  struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1407  _Hash, _RangeHash, _Unused, true>
1408  : public _Node_iterator_base<_Value, true>
1409  {
1410  protected:
1411  using __base_node_iter = _Node_iterator_base<_Value, true>;
1412  using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1413  _Hash, _RangeHash, _Unused, true>;
1414 
1415  _Local_iterator_base() = default;
1416  _Local_iterator_base(const __hash_code_base&,
1417  _Hash_node<_Value, true>* __p,
1418  std::size_t __bkt, std::size_t __bkt_count)
1419  : __base_node_iter(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1420  { }
1421 
1422  void
1423  _M_incr()
1424  {
1425  __base_node_iter::_M_incr();
1426  if (this->_M_cur)
1427  {
1428  std::size_t __bkt
1429  = _RangeHash{}(this->_M_cur->_M_hash_code, _M_bucket_count);
1430  if (__bkt != _M_bucket)
1431  this->_M_cur = nullptr;
1432  }
1433  }
1434 
1435  std::size_t _M_bucket;
1436  std::size_t _M_bucket_count;
1437 
1438  public:
1439  std::size_t
1440  _M_get_bucket() const { return _M_bucket; } // for debug mode
1441  };
1442 
1443  // Uninitialized storage for a _Hash_code_base.
1444  // This type is DefaultConstructible and Assignable even if the
1445  // _Hash_code_base type isn't, so that _Local_iterator_base<..., false>
1446  // can be DefaultConstructible and Assignable.
1447  template<typename _Tp, bool _IsEmpty = std::is_empty<_Tp>::value>
1448  struct _Hash_code_storage
1449  {
1450  __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
1451 
1452  _Tp*
1453  _M_h() { return _M_storage._M_ptr(); }
1454 
1455  const _Tp*
1456  _M_h() const { return _M_storage._M_ptr(); }
1457  };
1458 
1459  // Empty partial specialization for empty _Hash_code_base types.
1460  template<typename _Tp>
1461  struct _Hash_code_storage<_Tp, true>
1462  {
1463  static_assert( std::is_empty<_Tp>::value, "Type must be empty" );
1464 
1465  // As _Tp is an empty type there will be no bytes written/read through
1466  // the cast pointer, so no strict-aliasing violation.
1467  _Tp*
1468  _M_h() { return reinterpret_cast<_Tp*>(this); }
1469 
1470  const _Tp*
1471  _M_h() const { return reinterpret_cast<const _Tp*>(this); }
1472  };
1473 
1474  template<typename _Key, typename _Value, typename _ExtractKey,
1475  typename _Hash, typename _RangeHash, typename _Unused>
1476  using __hash_code_for_local_iter
1477  = _Hash_code_storage<_Hash_code_base<_Key, _Value, _ExtractKey,
1478  _Hash, _RangeHash, _Unused, false>>;
1479 
1480  // Partial specialization used when hash codes are not cached
1481  template<typename _Key, typename _Value, typename _ExtractKey,
1482  typename _Hash, typename _RangeHash, typename _Unused>
1483  struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1484  _Hash, _RangeHash, _Unused, false>
1485  : __hash_code_for_local_iter<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1486  _Unused>
1487  , _Node_iterator_base<_Value, false>
1488  {
1489  protected:
1490  using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1491  _Hash, _RangeHash, _Unused, false>;
1492  using __node_iter_base = _Node_iterator_base<_Value, false>;
1493 
1494  _Local_iterator_base() : _M_bucket_count(-1) { }
1495 
1496  _Local_iterator_base(const __hash_code_base& __base,
1497  _Hash_node<_Value, false>* __p,
1498  std::size_t __bkt, std::size_t __bkt_count)
1499  : __node_iter_base(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1500  { _M_init(__base); }
1501 
1502  ~_Local_iterator_base()
1503  {
1504  if (_M_bucket_count != size_t(-1))
1505  _M_destroy();
1506  }
1507 
1508  _Local_iterator_base(const _Local_iterator_base& __iter)
1509  : __node_iter_base(__iter._M_cur), _M_bucket(__iter._M_bucket)
1510  , _M_bucket_count(__iter._M_bucket_count)
1511  {
1512  if (_M_bucket_count != size_t(-1))
1513  _M_init(*__iter._M_h());
1514  }
1515 
1516  _Local_iterator_base&
1517  operator=(const _Local_iterator_base& __iter)
1518  {
1519  if (_M_bucket_count != -1)
1520  _M_destroy();
1521  this->_M_cur = __iter._M_cur;
1522  _M_bucket = __iter._M_bucket;
1523  _M_bucket_count = __iter._M_bucket_count;
1524  if (_M_bucket_count != -1)
1525  _M_init(*__iter._M_h());
1526  return *this;
1527  }
1528 
1529  void
1530  _M_incr()
1531  {
1532  __node_iter_base::_M_incr();
1533  if (this->_M_cur)
1534  {
1535  std::size_t __bkt = this->_M_h()->_M_bucket_index(*this->_M_cur,
1536  _M_bucket_count);
1537  if (__bkt != _M_bucket)
1538  this->_M_cur = nullptr;
1539  }
1540  }
1541 
1542  std::size_t _M_bucket;
1543  std::size_t _M_bucket_count;
1544 
1545  void
1546  _M_init(const __hash_code_base& __base)
1547  { ::new(this->_M_h()) __hash_code_base(__base); }
1548 
1549  void
1550  _M_destroy() { this->_M_h()->~__hash_code_base(); }
1551 
1552  public:
1553  std::size_t
1554  _M_get_bucket() const { return _M_bucket; } // for debug mode
1555  };
1556 
1557  /// local iterators
1558  template<typename _Key, typename _Value, typename _ExtractKey,
1559  typename _Hash, typename _RangeHash, typename _Unused,
1560  bool __constant_iterators, bool __cache>
1561  struct _Local_iterator
1562  : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1563  _Hash, _RangeHash, _Unused, __cache>
1564  {
1565  private:
1566  using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1567  _Hash, _RangeHash, _Unused, __cache>;
1568  using __hash_code_base = typename __base_type::__hash_code_base;
1569 
1570  public:
1571  using value_type = _Value;
1572  using pointer = __conditional_t<__constant_iterators,
1573  const value_type*, value_type*>;
1574  using reference = __conditional_t<__constant_iterators,
1575  const value_type&, value_type&>;
1576  using difference_type = ptrdiff_t;
1577  using iterator_category = forward_iterator_tag;
1578 
1579  _Local_iterator() = default;
1580 
1581  _Local_iterator(const __hash_code_base& __base,
1582  _Hash_node<_Value, __cache>* __n,
1583  std::size_t __bkt, std::size_t __bkt_count)
1584  : __base_type(__base, __n, __bkt, __bkt_count)
1585  { }
1586 
1587  reference
1588  operator*() const
1589  { return this->_M_cur->_M_v(); }
1590 
1591  pointer
1592  operator->() const
1593  { return this->_M_cur->_M_valptr(); }
1594 
1595  _Local_iterator&
1596  operator++()
1597  {
1598  this->_M_incr();
1599  return *this;
1600  }
1601 
1602  _Local_iterator
1603  operator++(int)
1604  {
1605  _Local_iterator __tmp(*this);
1606  this->_M_incr();
1607  return __tmp;
1608  }
1609  };
1610 
1611  /// local const_iterators
1612  template<typename _Key, typename _Value, typename _ExtractKey,
1613  typename _Hash, typename _RangeHash, typename _Unused,
1614  bool __constant_iterators, bool __cache>
1615  struct _Local_const_iterator
1616  : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1617  _Hash, _RangeHash, _Unused, __cache>
1618  {
1619  private:
1620  using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1621  _Hash, _RangeHash, _Unused, __cache>;
1622  using __hash_code_base = typename __base_type::__hash_code_base;
1623 
1624  public:
1625  typedef _Value value_type;
1626  typedef const value_type* pointer;
1627  typedef const value_type& reference;
1628  typedef std::ptrdiff_t difference_type;
1629  typedef std::forward_iterator_tag iterator_category;
1630 
1631  _Local_const_iterator() = default;
1632 
1633  _Local_const_iterator(const __hash_code_base& __base,
1634  _Hash_node<_Value, __cache>* __n,
1635  std::size_t __bkt, std::size_t __bkt_count)
1636  : __base_type(__base, __n, __bkt, __bkt_count)
1637  { }
1638 
1639  _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
1640  _Hash, _RangeHash, _Unused,
1641  __constant_iterators,
1642  __cache>& __x)
1643  : __base_type(__x)
1644  { }
1645 
1646  reference
1647  operator*() const
1648  { return this->_M_cur->_M_v(); }
1649 
1650  pointer
1651  operator->() const
1652  { return this->_M_cur->_M_valptr(); }
1653 
1654  _Local_const_iterator&
1655  operator++()
1656  {
1657  this->_M_incr();
1658  return *this;
1659  }
1660 
1661  _Local_const_iterator
1662  operator++(int)
1663  {
1664  _Local_const_iterator __tmp(*this);
1665  this->_M_incr();
1666  return __tmp;
1667  }
1668  };
1669 
1670  /**
1671  * Primary class template _Hashtable_base.
1672  *
1673  * Helper class adding management of _Equal functor to
1674  * _Hash_code_base type.
1675  *
1676  * Base class templates are:
1677  * - __detail::_Hash_code_base
1678  * - __detail::_Hashtable_ebo_helper
1679  */
1680  template<typename _Key, typename _Value, typename _ExtractKey,
1681  typename _Equal, typename _Hash, typename _RangeHash,
1682  typename _Unused, typename _Traits>
1683  struct _Hashtable_base
1684  : public _Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1685  _Unused, _Traits::__hash_cached::value>,
1686  private _Hashtable_ebo_helper<0, _Equal>
1687  {
1688  public:
1689  typedef _Key key_type;
1690  typedef _Value value_type;
1691  typedef _Equal key_equal;
1692  typedef std::size_t size_type;
1693  typedef std::ptrdiff_t difference_type;
1694 
1695  using __traits_type = _Traits;
1696  using __hash_cached = typename __traits_type::__hash_cached;
1697 
1698  using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1699  _Hash, _RangeHash, _Unused,
1700  __hash_cached::value>;
1701 
1702  using __hash_code = typename __hash_code_base::__hash_code;
1703 
1704  private:
1705  using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>;
1706 
1707  static bool
1708  _S_equals(__hash_code, const _Hash_node_code_cache<false>&)
1709  { return true; }
1710 
1711  static bool
1712  _S_node_equals(const _Hash_node_code_cache<false>&,
1713  const _Hash_node_code_cache<false>&)
1714  { return true; }
1715 
1716  static bool
1717  _S_equals(__hash_code __c, const _Hash_node_code_cache<true>& __n)
1718  { return __c == __n._M_hash_code; }
1719 
1720  static bool
1721  _S_node_equals(const _Hash_node_code_cache<true>& __lhn,
1722  const _Hash_node_code_cache<true>& __rhn)
1723  { return __lhn._M_hash_code == __rhn._M_hash_code; }
1724 
1725  protected:
1726  _Hashtable_base() = default;
1727 
1728  _Hashtable_base(const _Hash& __hash, const _Equal& __eq)
1729  : __hash_code_base(__hash), _EqualEBO(__eq)
1730  { }
1731 
1732  bool
1733  _M_key_equals(const _Key& __k,
1734  const _Hash_node_value<_Value,
1735  __hash_cached::value>& __n) const
1736  {
1737  static_assert(__is_invocable<const _Equal&, const _Key&, const _Key&>{},
1738  "key equality predicate must be invocable with two arguments of "
1739  "key type");
1740  return _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1741  }
1742 
1743  template<typename _Kt>
1744  bool
1745  _M_key_equals_tr(const _Kt& __k,
1746  const _Hash_node_value<_Value,
1747  __hash_cached::value>& __n) const
1748  {
1749  static_assert(
1750  __is_invocable<const _Equal&, const _Kt&, const _Key&>{},
1751  "key equality predicate must be invocable with two arguments of "
1752  "key type");
1753  return _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1754  }
1755 
1756  bool
1757  _M_equals(const _Key& __k, __hash_code __c,
1758  const _Hash_node_value<_Value, __hash_cached::value>& __n) const
1759  { return _S_equals(__c, __n) && _M_key_equals(__k, __n); }
1760 
1761  template<typename _Kt>
1762  bool
1763  _M_equals_tr(const _Kt& __k, __hash_code __c,
1764  const _Hash_node_value<_Value,
1765  __hash_cached::value>& __n) const
1766  { return _S_equals(__c, __n) && _M_key_equals_tr(__k, __n); }
1767 
1768  bool
1769  _M_node_equals(
1770  const _Hash_node_value<_Value, __hash_cached::value>& __lhn,
1771  const _Hash_node_value<_Value, __hash_cached::value>& __rhn) const
1772  {
1773  return _S_node_equals(__lhn, __rhn)
1774  && _M_key_equals(_ExtractKey{}(__lhn._M_v()), __rhn);
1775  }
1776 
1777  void
1778  _M_swap(_Hashtable_base& __x)
1779  {
1780  __hash_code_base::_M_swap(__x);
1781  std::swap(_EqualEBO::_M_get(), __x._EqualEBO::_M_get());
1782  }
1783 
1784  const _Equal&
1785  _M_eq() const { return _EqualEBO::_M_cget(); }
1786  };
1787 
1788  /**
1789  * Primary class template _Equality.
1790  *
1791  * This is for implementing equality comparison for unordered
1792  * containers, per N3068, by John Lakos and Pablo Halpern.
1793  * Algorithmically, we follow closely the reference implementations
1794  * therein.
1795  */
1796  template<typename _Key, typename _Value, typename _Alloc,
1797  typename _ExtractKey, typename _Equal,
1798  typename _Hash, typename _RangeHash, typename _Unused,
1799  typename _RehashPolicy, typename _Traits,
1800  bool _Unique_keys = _Traits::__unique_keys::value>
1801  struct _Equality;
1802 
1803  /// unordered_map and unordered_set specializations.
1804  template<typename _Key, typename _Value, typename _Alloc,
1805  typename _ExtractKey, typename _Equal,
1806  typename _Hash, typename _RangeHash, typename _Unused,
1807  typename _RehashPolicy, typename _Traits>
1808  struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1809  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
1810  {
1811  using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1812  _Hash, _RangeHash, _Unused,
1813  _RehashPolicy, _Traits>;
1814 
1815  bool
1816  _M_equal(const __hashtable&) const;
1817  };
1818 
1819  template<typename _Key, typename _Value, typename _Alloc,
1820  typename _ExtractKey, typename _Equal,
1821  typename _Hash, typename _RangeHash, typename _Unused,
1822  typename _RehashPolicy, typename _Traits>
1823  bool
1824  _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1825  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
1826  _M_equal(const __hashtable& __other) const
1827  {
1828  using __node_ptr = typename __hashtable::__node_ptr;
1829  const __hashtable* __this = static_cast<const __hashtable*>(this);
1830  if (__this->size() != __other.size())
1831  return false;
1832 
1833  for (auto __x_n = __this->_M_begin(); __x_n; __x_n = __x_n->_M_next())
1834  {
1835  std::size_t __ybkt = __other._M_bucket_index(*__x_n);
1836  auto __prev_n = __other._M_buckets[__ybkt];
1837  if (!__prev_n)
1838  return false;
1839 
1840  for (__node_ptr __n = static_cast<__node_ptr>(__prev_n->_M_nxt);;
1841  __n = __n->_M_next())
1842  {
1843  if (__n->_M_v() == __x_n->_M_v())
1844  break;
1845 
1846  if (!__n->_M_nxt
1847  || __other._M_bucket_index(*__n->_M_next()) != __ybkt)
1848  return false;
1849  }
1850  }
1851 
1852  return true;
1853  }
1854 
1855  /// unordered_multiset and unordered_multimap specializations.
1856  template<typename _Key, typename _Value, typename _Alloc,
1857  typename _ExtractKey, typename _Equal,
1858  typename _Hash, typename _RangeHash, typename _Unused,
1859  typename _RehashPolicy, typename _Traits>
1860  struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1861  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
1862  {
1863  using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1864  _Hash, _RangeHash, _Unused,
1865  _RehashPolicy, _Traits>;
1866 
1867  bool
1868  _M_equal(const __hashtable&) const;
1869  };
1870 
1871  template<typename _Key, typename _Value, typename _Alloc,
1872  typename _ExtractKey, typename _Equal,
1873  typename _Hash, typename _RangeHash, typename _Unused,
1874  typename _RehashPolicy, typename _Traits>
1875  bool
1876  _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1877  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>::
1878  _M_equal(const __hashtable& __other) const
1879  {
1880  using __node_ptr = typename __hashtable::__node_ptr;
1881  using const_iterator = typename __hashtable::const_iterator;
1882  const __hashtable* __this = static_cast<const __hashtable*>(this);
1883  if (__this->size() != __other.size())
1884  return false;
1885 
1886  for (auto __x_n = __this->_M_begin(); __x_n;)
1887  {
1888  std::size_t __x_count = 1;
1889  auto __x_n_end = __x_n->_M_next();
1890  for (; __x_n_end
1891  && __this->key_eq()(_ExtractKey{}(__x_n->_M_v()),
1892  _ExtractKey{}(__x_n_end->_M_v()));
1893  __x_n_end = __x_n_end->_M_next())
1894  ++__x_count;
1895 
1896  std::size_t __ybkt = __other._M_bucket_index(*__x_n);
1897  auto __y_prev_n = __other._M_buckets[__ybkt];
1898  if (!__y_prev_n)
1899  return false;
1900 
1901  __node_ptr __y_n = static_cast<__node_ptr>(__y_prev_n->_M_nxt);
1902  for (;;)
1903  {
1904  if (__this->key_eq()(_ExtractKey{}(__y_n->_M_v()),
1905  _ExtractKey{}(__x_n->_M_v())))
1906  break;
1907 
1908  auto __y_ref_n = __y_n;
1909  for (__y_n = __y_n->_M_next(); __y_n; __y_n = __y_n->_M_next())
1910  if (!__other._M_node_equals(*__y_ref_n, *__y_n))
1911  break;
1912 
1913  if (!__y_n || __other._M_bucket_index(*__y_n) != __ybkt)
1914  return false;
1915  }
1916 
1917  auto __y_n_end = __y_n;
1918  for (; __y_n_end; __y_n_end = __y_n_end->_M_next())
1919  if (--__x_count == 0)
1920  break;
1921 
1922  if (__x_count != 0)
1923  return false;
1924 
1925  const_iterator __itx(__x_n), __itx_end(__x_n_end);
1926  const_iterator __ity(__y_n);
1927  if (!std::is_permutation(__itx, __itx_end, __ity))
1928  return false;
1929 
1930  __x_n = __x_n_end;
1931  }
1932  return true;
1933  }
1934 
1935  /**
1936  * This type deals with all allocation and keeps an allocator instance
1937  * through inheritance to benefit from EBO when possible.
1938  */
1939  template<typename _NodeAlloc>
1940  struct _Hashtable_alloc : private _Hashtable_ebo_helper<0, _NodeAlloc>
1941  {
1942  private:
1943  using __ebo_node_alloc = _Hashtable_ebo_helper<0, _NodeAlloc>;
1944 
1945  template<typename>
1946  struct __get_value_type;
1947  template<typename _Val, bool _Cache_hash_code>
1948  struct __get_value_type<_Hash_node<_Val, _Cache_hash_code>>
1949  { using type = _Val; };
1950 
1951  public:
1952  using __node_type = typename _NodeAlloc::value_type;
1953  using __node_alloc_type = _NodeAlloc;
1954  // Use __gnu_cxx to benefit from _S_always_equal and al.
1955  using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
1956 
1957  using __value_alloc_traits = typename __node_alloc_traits::template
1958  rebind_traits<typename __get_value_type<__node_type>::type>;
1959 
1960  using __node_ptr = __node_type*;
1961  using __node_base = _Hash_node_base;
1962  using __node_base_ptr = __node_base*;
1963  using __buckets_alloc_type =
1964  __alloc_rebind<__node_alloc_type, __node_base_ptr>;
1965  using __buckets_alloc_traits = std::allocator_traits<__buckets_alloc_type>;
1966  using __buckets_ptr = __node_base_ptr*;
1967 
1968  _Hashtable_alloc() = default;
1969  _Hashtable_alloc(const _Hashtable_alloc&) = default;
1970  _Hashtable_alloc(_Hashtable_alloc&&) = default;
1971 
1972  template<typename _Alloc>
1973  _Hashtable_alloc(_Alloc&& __a)
1974  : __ebo_node_alloc(std::forward<_Alloc>(__a))
1975  { }
1976 
1977  __node_alloc_type&
1978  _M_node_allocator()
1979  { return __ebo_node_alloc::_M_get(); }
1980 
1981  const __node_alloc_type&
1982  _M_node_allocator() const
1983  { return __ebo_node_alloc::_M_cget(); }
1984 
1985  // Allocate a node and construct an element within it.
1986  template<typename... _Args>
1987  __node_ptr
1988  _M_allocate_node(_Args&&... __args);
1989 
1990  // Destroy the element within a node and deallocate the node.
1991  void
1992  _M_deallocate_node(__node_ptr __n);
1993 
1994  // Deallocate a node.
1995  void
1996  _M_deallocate_node_ptr(__node_ptr __n);
1997 
1998  // Deallocate the linked list of nodes pointed to by __n.
1999  // The elements within the nodes are destroyed.
2000  void
2001  _M_deallocate_nodes(__node_ptr __n);
2002 
2003  __buckets_ptr
2004  _M_allocate_buckets(std::size_t __bkt_count);
2005 
2006  void
2007  _M_deallocate_buckets(__buckets_ptr, std::size_t __bkt_count);
2008  };
2009 
2010  // Definitions of class template _Hashtable_alloc's out-of-line member
2011  // functions.
2012  template<typename _NodeAlloc>
2013  template<typename... _Args>
2014  auto
2015  _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
2016  -> __node_ptr
2017  {
2018  auto& __alloc = _M_node_allocator();
2019  auto __nptr = __node_alloc_traits::allocate(__alloc, 1);
2020  __node_ptr __n = std::__to_address(__nptr);
2021  __try
2022  {
2023  ::new ((void*)__n) __node_type;
2024  __node_alloc_traits::construct(__alloc, __n->_M_valptr(),
2025  std::forward<_Args>(__args)...);
2026  return __n;
2027  }
2028  __catch(...)
2029  {
2030  __n->~__node_type();
2031  __node_alloc_traits::deallocate(__alloc, __nptr, 1);
2032  __throw_exception_again;
2033  }
2034  }
2035 
2036  template<typename _NodeAlloc>
2037  void
2038  _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_ptr __n)
2039  {
2040  __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
2041  _M_deallocate_node_ptr(__n);
2042  }
2043 
2044  template<typename _NodeAlloc>
2045  void
2046  _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node_ptr(__node_ptr __n)
2047  {
2048  typedef typename __node_alloc_traits::pointer _Ptr;
2049  auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
2050  __n->~__node_type();
2051  __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
2052  }
2053 
2054  template<typename _NodeAlloc>
2055  void
2056  _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_ptr __n)
2057  {
2058  while (__n)
2059  {
2060  __node_ptr __tmp = __n;
2061  __n = __n->_M_next();
2062  _M_deallocate_node(__tmp);
2063  }
2064  }
2065 
2066  template<typename _NodeAlloc>
2067  auto
2068  _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(std::size_t __bkt_count)
2069  -> __buckets_ptr
2070  {
2071  __buckets_alloc_type __alloc(_M_node_allocator());
2072 
2073  auto __ptr = __buckets_alloc_traits::allocate(__alloc, __bkt_count);
2074  __buckets_ptr __p = std::__to_address(__ptr);
2075  __builtin_memset(__p, 0, __bkt_count * sizeof(__node_base_ptr));
2076  return __p;
2077  }
2078 
2079  template<typename _NodeAlloc>
2080  void
2081  _Hashtable_alloc<_NodeAlloc>::
2082  _M_deallocate_buckets(__buckets_ptr __bkts,
2083  std::size_t __bkt_count)
2084  {
2085  typedef typename __buckets_alloc_traits::pointer _Ptr;
2086  auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
2087  __buckets_alloc_type __alloc(_M_node_allocator());
2088  __buckets_alloc_traits::deallocate(__alloc, __ptr, __bkt_count);
2089  }
2090 
2091  ///@} hashtable-detail
2092 } // namespace __detail
2093 /// @endcond
2094 _GLIBCXX_END_NAMESPACE_VERSION
2095 } // namespace std
2096 
2097 #endif // _HASHTABLE_POLICY_H
ISO C++ entities toplevel namespace is std.
Forward iterators support a superset of input iterator operations.
Primary class template, tuple.
Definition: tuple:66
__bool_constant< false > false_type
The type used as a compile-time boolean with false value.
Definition: type_traits:114
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition: move.h:70
constexpr _Iterator __base(_Iterator __it)
Uniform interface to C++98 and C++11 allocators.
constexpr piecewise_construct_t piecewise_construct
Tag for piecewise construction of std::pair objects.
Definition: stl_pair.h:82
is_constructible
Definition: type_traits:1115
constexpr iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
Definition: simd.h:306
Struct holding two objects of arbitrary type.
is_empty
Definition: type_traits:913
__bool_constant< true > true_type
The type used as a compile-time boolean with true value.
Definition: type_traits:111
Define a member typedef type only if a boolean constant is true.
Definition: type_traits:128
Uniform interface to all pointer-like types.
Definition: ptr_traits.h:177
Uniform interface to all allocator types.
constexpr complex< _Tp > operator*(const complex< _Tp > &__x, const complex< _Tp > &__y)
Return new complex value x times y.
Definition: complex:400
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:126
constexpr tuple< _Elements &&... > forward_as_tuple(_Elements &&... __args) noexcept
Create a tuple of lvalue or rvalue references to the arguments.
Definition: tuple:2650
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
Traits class for iterators.
Marking input iterators.
__numeric_traits_integer< _Tp > __int_traits
Convenience alias for __numeric_traits<integer-type>.
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition: move.h:51