libstdc++
hashtable_policy.h
Go to the documentation of this file.
1 // Internal policy header for unordered_set and unordered_map -*- C++ -*-
2 
3 // Copyright (C) 2010-2021 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/stl_algobase.h> // for std::min, std::is_permutation.
36 #include <ext/numeric_traits.h> // for __gnu_cxx::__int_traits
37 
38 namespace std _GLIBCXX_VISIBILITY(default)
39 {
40 _GLIBCXX_BEGIN_NAMESPACE_VERSION
41 
42  template<typename _Key, typename _Value, typename _Alloc,
43  typename _ExtractKey, typename _Equal,
44  typename _Hash, typename _RangeHash, typename _Unused,
45  typename _RehashPolicy, typename _Traits>
46  class _Hashtable;
47 
48 namespace __detail
49 {
50  /**
51  * @defgroup hashtable-detail Base and Implementation Classes
52  * @ingroup unordered_associative_containers
53  * @{
54  */
55  template<typename _Key, typename _Value, typename _ExtractKey,
56  typename _Equal, typename _Hash, typename _RangeHash,
57  typename _Unused, typename _Traits>
59 
60  // Helper function: return distance(first, last) for forward
61  // iterators, or 0/1 for input iterators.
62  template<class _Iterator>
64  __distance_fw(_Iterator __first, _Iterator __last,
66  { return __first != __last ? 1 : 0; }
67 
68  template<class _Iterator>
70  __distance_fw(_Iterator __first, _Iterator __last,
72  { return std::distance(__first, __last); }
73 
74  template<class _Iterator>
76  __distance_fw(_Iterator __first, _Iterator __last)
77  { return __distance_fw(__first, __last,
78  std::__iterator_category(__first)); }
79 
80  struct _Identity
81  {
82  template<typename _Tp>
83  _Tp&&
84  operator()(_Tp&& __x) const noexcept
85  { return std::forward<_Tp>(__x); }
86  };
87 
88  struct _Select1st
89  {
90  template<typename _Tp>
91  auto
92  operator()(_Tp&& __x) const noexcept
93  -> decltype(std::get<0>(std::forward<_Tp>(__x)))
94  { return std::get<0>(std::forward<_Tp>(__x)); }
95  };
96 
97  template<typename _NodeAlloc>
99 
100  // Functor recycling a pool of nodes and using allocation once the pool is
101  // empty.
102  template<typename _NodeAlloc>
103  struct _ReuseOrAllocNode
104  {
105  private:
106  using __node_alloc_type = _NodeAlloc;
107  using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
108  using __node_alloc_traits =
109  typename __hashtable_alloc::__node_alloc_traits;
110  using __node_type = typename __hashtable_alloc::__node_type;
111 
112  public:
113  _ReuseOrAllocNode(__node_type* __nodes, __hashtable_alloc& __h)
114  : _M_nodes(__nodes), _M_h(__h) { }
115  _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;
116 
117  ~_ReuseOrAllocNode()
118  { _M_h._M_deallocate_nodes(_M_nodes); }
119 
120  template<typename _Arg>
121  __node_type*
122  operator()(_Arg&& __arg) const
123  {
124  if (_M_nodes)
125  {
126  __node_type* __node = _M_nodes;
127  _M_nodes = _M_nodes->_M_next();
128  __node->_M_nxt = nullptr;
129  auto& __a = _M_h._M_node_allocator();
130  __node_alloc_traits::destroy(__a, __node->_M_valptr());
131  __try
132  {
133  __node_alloc_traits::construct(__a, __node->_M_valptr(),
134  std::forward<_Arg>(__arg));
135  }
136  __catch(...)
137  {
138  _M_h._M_deallocate_node_ptr(__node);
139  __throw_exception_again;
140  }
141  return __node;
142  }
143  return _M_h._M_allocate_node(std::forward<_Arg>(__arg));
144  }
145 
146  private:
147  mutable __node_type* _M_nodes;
148  __hashtable_alloc& _M_h;
149  };
150 
151  // Functor similar to the previous one but without any pool of nodes to
152  // recycle.
153  template<typename _NodeAlloc>
154  struct _AllocNode
155  {
156  private:
157  using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
158  using __node_type = typename __hashtable_alloc::__node_type;
159 
160  public:
161  _AllocNode(__hashtable_alloc& __h)
162  : _M_h(__h) { }
163 
164  template<typename _Arg>
165  __node_type*
166  operator()(_Arg&& __arg) const
167  { return _M_h._M_allocate_node(std::forward<_Arg>(__arg)); }
168 
169  private:
170  __hashtable_alloc& _M_h;
171  };
172 
173  // Auxiliary types used for all instantiations of _Hashtable nodes
174  // and iterators.
175 
176  /**
177  * struct _Hashtable_traits
178  *
179  * Important traits for hash tables.
180  *
181  * @tparam _Cache_hash_code Boolean value. True if the value of
182  * the hash function is stored along with the value. This is a
183  * time-space tradeoff. Storing it may improve lookup speed by
184  * reducing the number of times we need to call the _Hash or _Equal
185  * functors.
186  *
187  * @tparam _Constant_iterators Boolean value. True if iterator and
188  * const_iterator are both constant iterator types. This is true
189  * for unordered_set and unordered_multiset, false for
190  * unordered_map and unordered_multimap.
191  *
192  * @tparam _Unique_keys Boolean value. True if the return value
193  * of _Hashtable::count(k) is always at most one, false if it may
194  * be an arbitrary number. This is true for unordered_set and
195  * unordered_map, false for unordered_multiset and
196  * unordered_multimap.
197  */
198  template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
200  {
204  };
205 
206  /**
207  * struct _Hash_node_base
208  *
209  * Nodes, used to wrap elements stored in the hash table. A policy
210  * template parameter of class template _Hashtable controls whether
211  * nodes also store a hash code. In some cases (e.g. strings) this
212  * may be a performance win.
213  */
215  {
216  _Hash_node_base* _M_nxt;
217 
218  _Hash_node_base() noexcept : _M_nxt() { }
219 
220  _Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
221  };
222 
223  /**
224  * struct _Hash_node_value_base
225  *
226  * Node type with the value to store.
227  */
228  template<typename _Value>
230  {
231  typedef _Value value_type;
232 
233  __gnu_cxx::__aligned_buffer<_Value> _M_storage;
234 
235  _Value*
236  _M_valptr() noexcept
237  { return _M_storage._M_ptr(); }
238 
239  const _Value*
240  _M_valptr() const noexcept
241  { return _M_storage._M_ptr(); }
242 
243  _Value&
244  _M_v() noexcept
245  { return *_M_valptr(); }
246 
247  const _Value&
248  _M_v() const noexcept
249  { return *_M_valptr(); }
250  };
251 
252  /**
253  * Primary template struct _Hash_node_code_cache.
254  */
255  template<bool _Cache_hash_code>
257  { };
258 
259  /**
260  * Specialization for node with cache, struct _Hash_node_code_cache.
261  */
262  template<>
264  { std::size_t _M_hash_code; };
265 
266  template<typename _Value, bool _Cache_hash_code>
267  struct _Hash_node_value
268  : _Hash_node_value_base<_Value>
269  , _Hash_node_code_cache<_Cache_hash_code>
270  { };
271 
272  /**
273  * Primary template struct _Hash_node.
274  */
275  template<typename _Value, bool _Cache_hash_code>
276  struct _Hash_node
278  , _Hash_node_value<_Value, _Cache_hash_code>
279  {
280  _Hash_node*
281  _M_next() const noexcept
282  { return static_cast<_Hash_node*>(this->_M_nxt); }
283  };
284 
285  /// Base class for node iterators.
286  template<typename _Value, bool _Cache_hash_code>
288  {
290 
291  __node_type* _M_cur;
292 
293  _Node_iterator_base() : _M_cur(nullptr) { }
294  _Node_iterator_base(__node_type* __p) noexcept
295  : _M_cur(__p) { }
296 
297  void
298  _M_incr() noexcept
299  { _M_cur = _M_cur->_M_next(); }
300 
301  friend bool
302  operator==(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
303  noexcept
304  { return __x._M_cur == __y._M_cur; }
305 
306 #if __cpp_impl_three_way_comparison < 201907L
307  friend bool
308  operator!=(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
309  noexcept
310  { return __x._M_cur != __y._M_cur; }
311 #endif
312  };
313 
314  /// Node iterators, used to iterate through all the hashtable.
315  template<typename _Value, bool __constant_iterators, bool __cache>
317  : public _Node_iterator_base<_Value, __cache>
318  {
319  private:
321  using __node_type = typename __base_type::__node_type;
322 
323  public:
324  typedef _Value value_type;
325  typedef std::ptrdiff_t difference_type;
327 
328  using pointer = typename std::conditional<__constant_iterators,
329  const value_type*, value_type*>::type;
330 
331  using reference = typename std::conditional<__constant_iterators,
332  const value_type&, value_type&>::type;
333 
334  _Node_iterator() = default;
335 
336  explicit
337  _Node_iterator(__node_type* __p) noexcept
338  : __base_type(__p) { }
339 
340  reference
341  operator*() const noexcept
342  { return this->_M_cur->_M_v(); }
343 
344  pointer
345  operator->() const noexcept
346  { return this->_M_cur->_M_valptr(); }
347 
349  operator++() noexcept
350  {
351  this->_M_incr();
352  return *this;
353  }
354 
356  operator++(int) noexcept
357  {
358  _Node_iterator __tmp(*this);
359  this->_M_incr();
360  return __tmp;
361  }
362  };
363 
364  /// Node const_iterators, used to iterate through all the hashtable.
365  template<typename _Value, bool __constant_iterators, bool __cache>
367  : public _Node_iterator_base<_Value, __cache>
368  {
369  private:
371  using __node_type = typename __base_type::__node_type;
372 
373  public:
374  typedef _Value value_type;
375  typedef std::ptrdiff_t difference_type;
377 
378  typedef const value_type* pointer;
379  typedef const value_type& reference;
380 
381  _Node_const_iterator() = default;
382 
383  explicit
384  _Node_const_iterator(__node_type* __p) noexcept
385  : __base_type(__p) { }
386 
387  _Node_const_iterator(const _Node_iterator<_Value, __constant_iterators,
388  __cache>& __x) noexcept
389  : __base_type(__x._M_cur) { }
390 
391  reference
392  operator*() const noexcept
393  { return this->_M_cur->_M_v(); }
394 
395  pointer
396  operator->() const noexcept
397  { return this->_M_cur->_M_valptr(); }
398 
400  operator++() noexcept
401  {
402  this->_M_incr();
403  return *this;
404  }
405 
407  operator++(int) noexcept
408  {
409  _Node_const_iterator __tmp(*this);
410  this->_M_incr();
411  return __tmp;
412  }
413  };
414 
415  // Many of class template _Hashtable's template parameters are policy
416  // classes. These are defaults for the policies.
417 
418  /// Default range hashing function: use division to fold a large number
419  /// into the range [0, N).
421  {
422  typedef std::size_t first_argument_type;
423  typedef std::size_t second_argument_type;
424  typedef std::size_t result_type;
425 
426  result_type
427  operator()(first_argument_type __num,
428  second_argument_type __den) const noexcept
429  { return __num % __den; }
430  };
431 
432  /// Default ranged hash function H. In principle it should be a
433  /// function object composed from objects of type H1 and H2 such that
434  /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
435  /// h1 and h2. So instead we'll just use a tag to tell class template
436  /// hashtable to do that composition.
438 
439  /// Default value for rehash policy. Bucket size is (usually) the
440  /// smallest prime that keeps the load factor small enough.
442  {
444 
445  _Prime_rehash_policy(float __z = 1.0) noexcept
446  : _M_max_load_factor(__z), _M_next_resize(0) { }
447 
448  float
449  max_load_factor() const noexcept
450  { return _M_max_load_factor; }
451 
452  // Return a bucket size no smaller than n.
453  std::size_t
454  _M_next_bkt(std::size_t __n) const;
455 
456  // Return a bucket count appropriate for n elements
457  std::size_t
458  _M_bkt_for_elements(std::size_t __n) const
459  { return __builtin_ceil(__n / (double)_M_max_load_factor); }
460 
461  // __n_bkt is current bucket count, __n_elt is current element count,
462  // and __n_ins is number of elements to be inserted. Do we need to
463  // increase bucket count? If so, return make_pair(true, n), where n
464  // is the new bucket count. If not, return make_pair(false, 0).
466  _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
467  std::size_t __n_ins) const;
468 
469  typedef std::size_t _State;
470 
471  _State
472  _M_state() const
473  { return _M_next_resize; }
474 
475  void
476  _M_reset() noexcept
477  { _M_next_resize = 0; }
478 
479  void
480  _M_reset(_State __state)
481  { _M_next_resize = __state; }
482 
483  static const std::size_t _S_growth_factor = 2;
484 
485  float _M_max_load_factor;
486  mutable std::size_t _M_next_resize;
487  };
488 
489  /// Range hashing function assuming that second arg is a power of 2.
491  {
492  typedef std::size_t first_argument_type;
493  typedef std::size_t second_argument_type;
494  typedef std::size_t result_type;
495 
496  result_type
497  operator()(first_argument_type __num,
498  second_argument_type __den) const noexcept
499  { return __num & (__den - 1); }
500  };
501 
502  /// Compute closest power of 2 not less than __n
503  inline std::size_t
504  __clp2(std::size_t __n) noexcept
505  {
507  // Equivalent to return __n ? std::bit_ceil(__n) : 0;
508  if (__n < 2)
509  return __n;
510  const unsigned __lz = sizeof(size_t) > sizeof(long)
511  ? __builtin_clzll(__n - 1ull)
512  : __builtin_clzl(__n - 1ul);
513  // Doing two shifts avoids undefined behaviour when __lz == 0.
514  return (size_t(1) << (__int_traits<size_t>::__digits - __lz - 1)) << 1;
515  }
516 
517  /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
518  /// operations.
520  {
522 
523  _Power2_rehash_policy(float __z = 1.0) noexcept
524  : _M_max_load_factor(__z), _M_next_resize(0) { }
525 
526  float
527  max_load_factor() const noexcept
528  { return _M_max_load_factor; }
529 
530  // Return a bucket size no smaller than n (as long as n is not above the
531  // highest power of 2).
532  std::size_t
533  _M_next_bkt(std::size_t __n) noexcept
534  {
535  if (__n == 0)
536  // Special case on container 1st initialization with 0 bucket count
537  // hint. We keep _M_next_resize to 0 to make sure that next time we
538  // want to add an element allocation will take place.
539  return 1;
540 
541  const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
542  const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
543  std::size_t __res = __clp2(__n);
544 
545  if (__res == 0)
546  __res = __max_bkt;
547  else if (__res == 1)
548  // If __res is 1 we force it to 2 to make sure there will be an
549  // allocation so that nothing need to be stored in the initial
550  // single bucket
551  __res = 2;
552 
553  if (__res == __max_bkt)
554  // Set next resize to the max value so that we never try to rehash again
555  // as we already reach the biggest possible bucket number.
556  // Note that it might result in max_load_factor not being respected.
557  _M_next_resize = size_t(-1);
558  else
559  _M_next_resize
560  = __builtin_floor(__res * (double)_M_max_load_factor);
561 
562  return __res;
563  }
564 
565  // Return a bucket count appropriate for n elements
566  std::size_t
567  _M_bkt_for_elements(std::size_t __n) const noexcept
568  { return __builtin_ceil(__n / (double)_M_max_load_factor); }
569 
570  // __n_bkt is current bucket count, __n_elt is current element count,
571  // and __n_ins is number of elements to be inserted. Do we need to
572  // increase bucket count? If so, return make_pair(true, n), where n
573  // is the new bucket count. If not, return make_pair(false, 0).
575  _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
576  std::size_t __n_ins) noexcept
577  {
578  if (__n_elt + __n_ins > _M_next_resize)
579  {
580  // If _M_next_resize is 0 it means that we have nothing allocated so
581  // far and that we start inserting elements. In this case we start
582  // with an initial bucket size of 11.
583  double __min_bkts
584  = std::max<std::size_t>(__n_elt + __n_ins, _M_next_resize ? 0 : 11)
585  / (double)_M_max_load_factor;
586  if (__min_bkts >= __n_bkt)
587  return { true,
588  _M_next_bkt(std::max<std::size_t>(__builtin_floor(__min_bkts) + 1,
589  __n_bkt * _S_growth_factor)) };
590 
591  _M_next_resize
592  = __builtin_floor(__n_bkt * (double)_M_max_load_factor);
593  return { false, 0 };
594  }
595  else
596  return { false, 0 };
597  }
598 
599  typedef std::size_t _State;
600 
601  _State
602  _M_state() const noexcept
603  { return _M_next_resize; }
604 
605  void
606  _M_reset() noexcept
607  { _M_next_resize = 0; }
608 
609  void
610  _M_reset(_State __state) noexcept
611  { _M_next_resize = __state; }
612 
613  static const std::size_t _S_growth_factor = 2;
614 
615  float _M_max_load_factor;
616  std::size_t _M_next_resize;
617  };
618 
619  // Base classes for std::_Hashtable. We define these base classes
620  // because in some cases we want to do different things depending on
621  // the value of a policy class. In some cases the policy class
622  // affects which member functions and nested typedefs are defined;
623  // we handle that by specializing base class templates. Several of
624  // the base class templates need to access other members of class
625  // template _Hashtable, so we use a variant of the "Curiously
626  // Recurring Template Pattern" (CRTP) technique.
627 
628  /**
629  * Primary class template _Map_base.
630  *
631  * If the hashtable has a value type of the form pair<T1, T2> and a
632  * key extraction policy (_ExtractKey) that returns the first part
633  * of the pair, the hashtable gets a mapped_type typedef. If it
634  * satisfies those criteria and also has unique keys, then it also
635  * gets an operator[].
636  */
637  template<typename _Key, typename _Value, typename _Alloc,
638  typename _ExtractKey, typename _Equal,
639  typename _Hash, typename _RangeHash, typename _Unused,
640  typename _RehashPolicy, typename _Traits,
641  bool _Unique_keys = _Traits::__unique_keys::value>
642  struct _Map_base { };
643 
644  /// Partial specialization, __unique_keys set to false.
645  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
646  typename _Hash, typename _RangeHash, typename _Unused,
647  typename _RehashPolicy, typename _Traits>
648  struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
649  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
650  {
651  using mapped_type = typename std::tuple_element<1, _Pair>::type;
652  };
653 
654  /// Partial specialization, __unique_keys set to true.
655  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
656  typename _Hash, typename _RangeHash, typename _Unused,
657  typename _RehashPolicy, typename _Traits>
658  struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
659  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
660  {
661  private:
662  using __hashtable_base = _Hashtable_base<_Key, _Pair, _Select1st, _Equal,
663  _Hash, _RangeHash, _Unused,
664  _Traits>;
665 
666  using __hashtable = _Hashtable<_Key, _Pair, _Alloc, _Select1st, _Equal,
667  _Hash, _RangeHash,
668  _Unused, _RehashPolicy, _Traits>;
669 
670  using __hash_code = typename __hashtable_base::__hash_code;
671 
672  public:
673  using key_type = typename __hashtable_base::key_type;
674  using mapped_type = typename std::tuple_element<1, _Pair>::type;
675 
676  mapped_type&
677  operator[](const key_type& __k);
678 
679  mapped_type&
680  operator[](key_type&& __k);
681 
682  // _GLIBCXX_RESOLVE_LIB_DEFECTS
683  // DR 761. unordered_map needs an at() member function.
684  mapped_type&
685  at(const key_type& __k);
686 
687  const mapped_type&
688  at(const key_type& __k) const;
689  };
690 
691  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
692  typename _Hash, typename _RangeHash, typename _Unused,
693  typename _RehashPolicy, typename _Traits>
694  auto
695  _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
696  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
697  operator[](const key_type& __k)
698  -> mapped_type&
699  {
700  __hashtable* __h = static_cast<__hashtable*>(this);
701  __hash_code __code = __h->_M_hash_code(__k);
702  std::size_t __bkt = __h->_M_bucket_index(__code);
703  if (auto __node = __h->_M_find_node(__bkt, __k, __code))
704  return __node->_M_v().second;
705 
706  typename __hashtable::_Scoped_node __node {
707  __h,
710  std::tuple<>()
711  };
712  auto __pos
713  = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
714  __node._M_node = nullptr;
715  return __pos->second;
716  }
717 
718  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
719  typename _Hash, typename _RangeHash, typename _Unused,
720  typename _RehashPolicy, typename _Traits>
721  auto
722  _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
723  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
724  operator[](key_type&& __k)
725  -> mapped_type&
726  {
727  __hashtable* __h = static_cast<__hashtable*>(this);
728  __hash_code __code = __h->_M_hash_code(__k);
729  std::size_t __bkt = __h->_M_bucket_index(__code);
730  if (auto __node = __h->_M_find_node(__bkt, __k, __code))
731  return __node->_M_v().second;
732 
733  typename __hashtable::_Scoped_node __node {
734  __h,
737  std::tuple<>()
738  };
739  auto __pos
740  = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
741  __node._M_node = nullptr;
742  return __pos->second;
743  }
744 
745  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
746  typename _Hash, typename _RangeHash, typename _Unused,
747  typename _RehashPolicy, typename _Traits>
748  auto
749  _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
750  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
751  at(const key_type& __k)
752  -> mapped_type&
753  {
754  __hashtable* __h = static_cast<__hashtable*>(this);
755  auto __ite = __h->find(__k);
756 
757  if (!__ite._M_cur)
758  __throw_out_of_range(__N("_Map_base::at"));
759  return __ite->second;
760  }
761 
762  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
763  typename _Hash, typename _RangeHash, typename _Unused,
764  typename _RehashPolicy, typename _Traits>
765  auto
766  _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
767  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
768  at(const key_type& __k) const
769  -> const mapped_type&
770  {
771  const __hashtable* __h = static_cast<const __hashtable*>(this);
772  auto __ite = __h->find(__k);
773 
774  if (!__ite._M_cur)
775  __throw_out_of_range(__N("_Map_base::at"));
776  return __ite->second;
777  }
778 
779  /**
780  * Primary class template _Insert_base.
781  *
782  * Defines @c insert member functions appropriate to all _Hashtables.
783  */
784  template<typename _Key, typename _Value, typename _Alloc,
785  typename _ExtractKey, typename _Equal,
786  typename _Hash, typename _RangeHash, typename _Unused,
787  typename _RehashPolicy, typename _Traits>
789  {
790  protected:
791  using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
792  _Equal, _Hash, _RangeHash,
793  _Unused, _Traits>;
794 
795  using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
796  _Hash, _RangeHash,
797  _Unused, _RehashPolicy, _Traits>;
798 
799  using __hash_cached = typename _Traits::__hash_cached;
800  using __constant_iterators = typename _Traits::__constant_iterators;
801 
803  __alloc_rebind<_Alloc, _Hash_node<_Value,
804  __hash_cached::value>>>;
805 
806  using value_type = typename __hashtable_base::value_type;
807  using size_type = typename __hashtable_base::size_type;
808 
809  using __unique_keys = typename _Traits::__unique_keys;
810  using __node_alloc_type = typename __hashtable_alloc::__node_alloc_type;
811  using __node_gen_type = _AllocNode<__node_alloc_type>;
812 
813  __hashtable&
814  _M_conjure_hashtable()
815  { return *(static_cast<__hashtable*>(this)); }
816 
817  template<typename _InputIterator, typename _NodeGetter>
818  void
819  _M_insert_range(_InputIterator __first, _InputIterator __last,
820  const _NodeGetter&, true_type __uks);
821 
822  template<typename _InputIterator, typename _NodeGetter>
823  void
824  _M_insert_range(_InputIterator __first, _InputIterator __last,
825  const _NodeGetter&, false_type __uks);
826 
827  public:
828  using iterator = _Node_iterator<_Value, __constant_iterators::value,
829  __hash_cached::value>;
830 
831  using const_iterator = _Node_const_iterator<_Value, __constant_iterators::value,
832  __hash_cached::value>;
833 
834  using __ireturn_type = typename std::conditional<__unique_keys::value,
836  iterator>::type;
837 
838  __ireturn_type
839  insert(const value_type& __v)
840  {
841  __hashtable& __h = _M_conjure_hashtable();
842  __node_gen_type __node_gen(__h);
843  return __h._M_insert(__v, __node_gen, __unique_keys{});
844  }
845 
846  iterator
847  insert(const_iterator __hint, const value_type& __v)
848  {
849  __hashtable& __h = _M_conjure_hashtable();
850  __node_gen_type __node_gen(__h);
851  return __h._M_insert(__hint, __v, __node_gen, __unique_keys{});
852  }
853 
854  template<typename _KType, typename... _Args>
856  try_emplace(const_iterator, _KType&& __k, _Args&&... __args)
857  {
858  __hashtable& __h = _M_conjure_hashtable();
859  auto __code = __h._M_hash_code(__k);
860  std::size_t __bkt = __h._M_bucket_index(__code);
861  if (auto __node = __h._M_find_node(__bkt, __k, __code))
862  return { iterator(__node), false };
863 
864  typename __hashtable::_Scoped_node __node {
865  &__h,
867  std::forward_as_tuple(std::forward<_KType>(__k)),
868  std::forward_as_tuple(std::forward<_Args>(__args)...)
869  };
870  auto __it
871  = __h._M_insert_unique_node(__bkt, __code, __node._M_node);
872  __node._M_node = nullptr;
873  return { __it, true };
874  }
875 
876  void
877  insert(initializer_list<value_type> __l)
878  { this->insert(__l.begin(), __l.end()); }
879 
880  template<typename _InputIterator>
881  void
882  insert(_InputIterator __first, _InputIterator __last)
883  {
884  __hashtable& __h = _M_conjure_hashtable();
885  __node_gen_type __node_gen(__h);
886  return _M_insert_range(__first, __last, __node_gen, __unique_keys{});
887  }
888  };
889 
890  template<typename _Key, typename _Value, typename _Alloc,
891  typename _ExtractKey, typename _Equal,
892  typename _Hash, typename _RangeHash, typename _Unused,
893  typename _RehashPolicy, typename _Traits>
894  template<typename _InputIterator, typename _NodeGetter>
895  void
896  _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
897  _Hash, _RangeHash, _Unused,
898  _RehashPolicy, _Traits>::
899  _M_insert_range(_InputIterator __first, _InputIterator __last,
900  const _NodeGetter& __node_gen, true_type __uks)
901  {
902  __hashtable& __h = _M_conjure_hashtable();
903  for (; __first != __last; ++__first)
904  __h._M_insert(*__first, __node_gen, __uks);
905  }
906 
907  template<typename _Key, typename _Value, typename _Alloc,
908  typename _ExtractKey, typename _Equal,
909  typename _Hash, typename _RangeHash, typename _Unused,
910  typename _RehashPolicy, typename _Traits>
911  template<typename _InputIterator, typename _NodeGetter>
912  void
913  _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
914  _Hash, _RangeHash, _Unused,
915  _RehashPolicy, _Traits>::
916  _M_insert_range(_InputIterator __first, _InputIterator __last,
917  const _NodeGetter& __node_gen, false_type __uks)
918  {
919  using __rehash_type = typename __hashtable::__rehash_type;
920  using __rehash_state = typename __hashtable::__rehash_state;
921  using pair_type = std::pair<bool, std::size_t>;
922 
923  size_type __n_elt = __detail::__distance_fw(__first, __last);
924  if (__n_elt == 0)
925  return;
926 
927  __hashtable& __h = _M_conjure_hashtable();
928  __rehash_type& __rehash = __h._M_rehash_policy;
929  const __rehash_state& __saved_state = __rehash._M_state();
930  pair_type __do_rehash = __rehash._M_need_rehash(__h._M_bucket_count,
931  __h._M_element_count,
932  __n_elt);
933 
934  if (__do_rehash.first)
935  __h._M_rehash(__do_rehash.second, __saved_state);
936 
937  for (; __first != __last; ++__first)
938  __h._M_insert(*__first, __node_gen, __uks);
939  }
940 
941  /**
942  * Primary class template _Insert.
943  *
944  * Defines @c insert member functions that depend on _Hashtable policies,
945  * via partial specializations.
946  */
947  template<typename _Key, typename _Value, typename _Alloc,
948  typename _ExtractKey, typename _Equal,
949  typename _Hash, typename _RangeHash, typename _Unused,
950  typename _RehashPolicy, typename _Traits,
951  bool _Constant_iterators = _Traits::__constant_iterators::value>
952  struct _Insert;
953 
954  /// Specialization.
955  template<typename _Key, typename _Value, typename _Alloc,
956  typename _ExtractKey, typename _Equal,
957  typename _Hash, typename _RangeHash, typename _Unused,
958  typename _RehashPolicy, typename _Traits>
959  struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
960  _Hash, _RangeHash, _Unused,
961  _RehashPolicy, _Traits, true>
962  : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
963  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>
964  {
965  using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
966  _Equal, _Hash, _RangeHash, _Unused,
967  _RehashPolicy, _Traits>;
968 
969  using value_type = typename __base_type::value_type;
970  using iterator = typename __base_type::iterator;
972  using __ireturn_type = typename __base_type::__ireturn_type;
973 
974  using __unique_keys = typename __base_type::__unique_keys;
975  using __hashtable = typename __base_type::__hashtable;
976  using __node_gen_type = typename __base_type::__node_gen_type;
977 
978  using __base_type::insert;
979 
980  __ireturn_type
981  insert(value_type&& __v)
982  {
983  __hashtable& __h = this->_M_conjure_hashtable();
984  __node_gen_type __node_gen(__h);
985  return __h._M_insert(std::move(__v), __node_gen, __unique_keys{});
986  }
987 
988  iterator
989  insert(const_iterator __hint, value_type&& __v)
990  {
991  __hashtable& __h = this->_M_conjure_hashtable();
992  __node_gen_type __node_gen(__h);
993  return __h._M_insert(__hint, std::move(__v), __node_gen,
994  __unique_keys{});
995  }
996  };
997 
998  /// Specialization.
999  template<typename _Key, typename _Value, typename _Alloc,
1000  typename _ExtractKey, typename _Equal,
1001  typename _Hash, typename _RangeHash, typename _Unused,
1002  typename _RehashPolicy, typename _Traits>
1003  struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1004  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
1005  : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1006  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>
1007  {
1008  using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
1009  _Equal, _Hash, _RangeHash, _Unused,
1010  _RehashPolicy, _Traits>;
1011  using value_type = typename __base_type::value_type;
1012  using iterator = typename __base_type::iterator;
1014 
1015  using __unique_keys = typename __base_type::__unique_keys;
1016  using __hashtable = typename __base_type::__hashtable;
1017  using __ireturn_type = typename __base_type::__ireturn_type;
1018 
1019  using __base_type::insert;
1020 
1021  template<typename _Pair>
1023 
1024  template<typename _Pair>
1026 
1027  template<typename _Pair>
1028  using _IFconsp = typename _IFcons<_Pair>::type;
1029 
1030  template<typename _Pair, typename = _IFconsp<_Pair>>
1031  __ireturn_type
1032  insert(_Pair&& __v)
1033  {
1034  __hashtable& __h = this->_M_conjure_hashtable();
1035  return __h._M_emplace(__unique_keys{}, std::forward<_Pair>(__v));
1036  }
1037 
1038  template<typename _Pair, typename = _IFconsp<_Pair>>
1039  iterator
1040  insert(const_iterator __hint, _Pair&& __v)
1041  {
1042  __hashtable& __h = this->_M_conjure_hashtable();
1043  return __h._M_emplace(__hint, __unique_keys{},
1044  std::forward<_Pair>(__v));
1045  }
1046  };
1047 
1048  template<typename _Policy>
1049  using __has_load_factor = typename _Policy::__has_load_factor;
1050 
1051  /**
1052  * Primary class template _Rehash_base.
1053  *
1054  * Give hashtable the max_load_factor functions and reserve iff the
1055  * rehash policy supports it.
1056  */
1057  template<typename _Key, typename _Value, typename _Alloc,
1058  typename _ExtractKey, typename _Equal,
1059  typename _Hash, typename _RangeHash, typename _Unused,
1060  typename _RehashPolicy, typename _Traits,
1061  typename =
1062  __detected_or_t<false_type, __has_load_factor, _RehashPolicy>>
1064 
1065  /// Specialization when rehash policy doesn't provide load factor management.
1066  template<typename _Key, typename _Value, typename _Alloc,
1067  typename _ExtractKey, typename _Equal,
1068  typename _Hash, typename _RangeHash, typename _Unused,
1069  typename _RehashPolicy, typename _Traits>
1070  struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1071  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
1072  false_type /* Has load factor */>
1073  {
1074  };
1075 
1076  /// Specialization when rehash policy provide load factor management.
1077  template<typename _Key, typename _Value, typename _Alloc,
1078  typename _ExtractKey, typename _Equal,
1079  typename _Hash, typename _RangeHash, typename _Unused,
1080  typename _RehashPolicy, typename _Traits>
1081  struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1082  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
1083  true_type /* Has load factor */>
1084  {
1085  using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
1086  _Equal, _Hash, _RangeHash, _Unused,
1087  _RehashPolicy, _Traits>;
1088 
1089  float
1090  max_load_factor() const noexcept
1091  {
1092  const __hashtable* __this = static_cast<const __hashtable*>(this);
1093  return __this->__rehash_policy().max_load_factor();
1094  }
1095 
1096  void
1097  max_load_factor(float __z)
1098  {
1099  __hashtable* __this = static_cast<__hashtable*>(this);
1100  __this->__rehash_policy(_RehashPolicy(__z));
1101  }
1102 
1103  void
1104  reserve(std::size_t __n)
1105  {
1106  __hashtable* __this = static_cast<__hashtable*>(this);
1107  __this->rehash(__this->__rehash_policy()._M_bkt_for_elements(__n));
1108  }
1109  };
1110 
1111  /**
1112  * Primary class template _Hashtable_ebo_helper.
1113  *
1114  * Helper class using EBO when it is not forbidden (the type is not
1115  * final) and when it is worth it (the type is empty.)
1116  */
1117  template<int _Nm, typename _Tp,
1118  bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
1120 
1121  /// Specialization using EBO.
1122  template<int _Nm, typename _Tp>
1123  struct _Hashtable_ebo_helper<_Nm, _Tp, true>
1124  : private _Tp
1125  {
1126  _Hashtable_ebo_helper() = default;
1127 
1128  template<typename _OtherTp>
1129  _Hashtable_ebo_helper(_OtherTp&& __tp)
1130  : _Tp(std::forward<_OtherTp>(__tp))
1131  { }
1132 
1133  const _Tp& _M_cget() const { return static_cast<const _Tp&>(*this); }
1134  _Tp& _M_get() { return static_cast<_Tp&>(*this); }
1135  };
1136 
1137  /// Specialization not using EBO.
1138  template<int _Nm, typename _Tp>
1139  struct _Hashtable_ebo_helper<_Nm, _Tp, false>
1140  {
1141  _Hashtable_ebo_helper() = default;
1142 
1143  template<typename _OtherTp>
1144  _Hashtable_ebo_helper(_OtherTp&& __tp)
1145  : _M_tp(std::forward<_OtherTp>(__tp))
1146  { }
1147 
1148  const _Tp& _M_cget() const { return _M_tp; }
1149  _Tp& _M_get() { return _M_tp; }
1150 
1151  private:
1152  _Tp _M_tp;
1153  };
1154 
1155  /**
1156  * Primary class template _Local_iterator_base.
1157  *
1158  * Base class for local iterators, used to iterate within a bucket
1159  * but not between buckets.
1160  */
1161  template<typename _Key, typename _Value, typename _ExtractKey,
1162  typename _Hash, typename _RangeHash, typename _Unused,
1163  bool __cache_hash_code>
1165 
1166  /**
1167  * Primary class template _Hash_code_base.
1168  *
1169  * Encapsulates two policy issues that aren't quite orthogonal.
1170  * (1) the difference between using a ranged hash function and using
1171  * the combination of a hash function and a range-hashing function.
1172  * In the former case we don't have such things as hash codes, so
1173  * we have a dummy type as placeholder.
1174  * (2) Whether or not we cache hash codes. Caching hash codes is
1175  * meaningless if we have a ranged hash function.
1176  *
1177  * We also put the key extraction objects here, for convenience.
1178  * Each specialization derives from one or more of the template
1179  * parameters to benefit from Ebo. This is important as this type
1180  * is inherited in some cases by the _Local_iterator_base type used
1181  * to implement local_iterator and const_local_iterator. As with
1182  * any iterator type we prefer to make it as small as possible.
1183  */
1184  template<typename _Key, typename _Value, typename _ExtractKey,
1185  typename _Hash, typename _RangeHash, typename _Unused,
1186  bool __cache_hash_code>
1188  : private _Hashtable_ebo_helper<1, _Hash>
1189  {
1190  private:
1192 
1193  // Gives the local iterator implementation access to _M_bucket_index().
1194  friend struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1195  _Hash, _RangeHash, _Unused, false>;
1196 
1197  public:
1198  typedef _Hash hasher;
1199 
1200  hasher
1201  hash_function() const
1202  { return _M_hash(); }
1203 
1204  protected:
1205  typedef std::size_t __hash_code;
1206 
1207  // We need the default constructor for the local iterators and _Hashtable
1208  // default constructor.
1209  _Hash_code_base() = default;
1210  _Hash_code_base(const _Hash& __hash) : __ebo_hash(__hash) { }
1211 
1212  __hash_code
1213  _M_hash_code(const _Key& __k) const
1214  {
1215  static_assert(__is_invocable<const _Hash&, const _Key&>{},
1216  "hash function must be invocable with an argument of key type");
1217  return _M_hash()(__k);
1218  }
1219 
1220  template<typename _Kt>
1221  __hash_code
1222  _M_hash_code_tr(const _Kt& __k) const
1223  {
1224  static_assert(__is_invocable<const _Hash&, const _Kt&>{},
1225  "hash function must be invocable with an argument of key type");
1226  return _M_hash()(__k);
1227  }
1228 
1229  std::size_t
1230  _M_bucket_index(__hash_code __c, std::size_t __bkt_count) const
1231  { return _RangeHash{}(__c, __bkt_count); }
1232 
1233  std::size_t
1234  _M_bucket_index(const _Hash_node_value<_Value, false>& __n,
1235  std::size_t __bkt_count) const
1236  noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>()))
1237  && noexcept(declval<const _RangeHash&>()((__hash_code)0,
1238  (std::size_t)0)) )
1239  {
1240  return _RangeHash{}(_M_hash_code(_ExtractKey{}(__n._M_v())),
1241  __bkt_count);
1242  }
1243 
1244  std::size_t
1245  _M_bucket_index(const _Hash_node_value<_Value, true>& __n,
1246  std::size_t __bkt_count) const
1247  noexcept( noexcept(declval<const _RangeHash&>()((__hash_code)0,
1248  (std::size_t)0)) )
1249  { return _RangeHash{}(__n._M_hash_code, __bkt_count); }
1250 
1251  void
1252  _M_store_code(_Hash_node_code_cache<false>&, __hash_code) const
1253  { }
1254 
1255  void
1256  _M_copy_code(_Hash_node_code_cache<false>&,
1257  const _Hash_node_code_cache<false>&) const
1258  { }
1259 
1260  void
1261  _M_store_code(_Hash_node_code_cache<true>& __n, __hash_code __c) const
1262  { __n._M_hash_code = __c; }
1263 
1264  void
1265  _M_copy_code(_Hash_node_code_cache<true>& __to,
1266  const _Hash_node_code_cache<true>& __from) const
1267  { __to._M_hash_code = __from._M_hash_code; }
1268 
1269  void
1270  _M_swap(_Hash_code_base& __x)
1271  { std::swap(__ebo_hash::_M_get(), __x.__ebo_hash::_M_get()); }
1272 
1273  const _Hash&
1274  _M_hash() const { return __ebo_hash::_M_cget(); }
1275  };
1276 
1277  /// Partial specialization used when nodes contain a cached hash code.
1278  template<typename _Key, typename _Value, typename _ExtractKey,
1279  typename _Hash, typename _RangeHash, typename _Unused>
1280  struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1281  _Hash, _RangeHash, _Unused, true>
1282  : public _Node_iterator_base<_Value, true>
1283  {
1284  protected:
1286  using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1287  _Hash, _RangeHash, _Unused, true>;
1288 
1289  _Local_iterator_base() = default;
1292  std::size_t __bkt, std::size_t __bkt_count)
1293  : __base_node_iter(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1294  { }
1295 
1296  void
1297  _M_incr()
1298  {
1299  __base_node_iter::_M_incr();
1300  if (this->_M_cur)
1301  {
1302  std::size_t __bkt
1303  = _RangeHash{}(this->_M_cur->_M_hash_code, _M_bucket_count);
1304  if (__bkt != _M_bucket)
1305  this->_M_cur = nullptr;
1306  }
1307  }
1308 
1309  std::size_t _M_bucket;
1310  std::size_t _M_bucket_count;
1311 
1312  public:
1313  std::size_t
1314  _M_get_bucket() const { return _M_bucket; } // for debug mode
1315  };
1316 
1317  // Uninitialized storage for a _Hash_code_base.
1318  // This type is DefaultConstructible and Assignable even if the
1319  // _Hash_code_base type isn't, so that _Local_iterator_base<..., false>
1320  // can be DefaultConstructible and Assignable.
1321  template<typename _Tp, bool _IsEmpty = std::is_empty<_Tp>::value>
1322  struct _Hash_code_storage
1323  {
1324  __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
1325 
1326  _Tp*
1327  _M_h() { return _M_storage._M_ptr(); }
1328 
1329  const _Tp*
1330  _M_h() const { return _M_storage._M_ptr(); }
1331  };
1332 
1333  // Empty partial specialization for empty _Hash_code_base types.
1334  template<typename _Tp>
1335  struct _Hash_code_storage<_Tp, true>
1336  {
1337  static_assert( std::is_empty<_Tp>::value, "Type must be empty" );
1338 
1339  // As _Tp is an empty type there will be no bytes written/read through
1340  // the cast pointer, so no strict-aliasing violation.
1341  _Tp*
1342  _M_h() { return reinterpret_cast<_Tp*>(this); }
1343 
1344  const _Tp*
1345  _M_h() const { return reinterpret_cast<const _Tp*>(this); }
1346  };
1347 
1348  template<typename _Key, typename _Value, typename _ExtractKey,
1349  typename _Hash, typename _RangeHash, typename _Unused>
1350  using __hash_code_for_local_iter
1351  = _Hash_code_storage<_Hash_code_base<_Key, _Value, _ExtractKey,
1352  _Hash, _RangeHash, _Unused, false>>;
1353 
1354  // Partial specialization used when hash codes are not cached
1355  template<typename _Key, typename _Value, typename _ExtractKey,
1356  typename _Hash, typename _RangeHash, typename _Unused>
1357  struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1358  _Hash, _RangeHash, _Unused, false>
1359  : __hash_code_for_local_iter<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1360  _Unused>
1361  , _Node_iterator_base<_Value, false>
1362  {
1363  protected:
1364  using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1365  _Hash, _RangeHash, _Unused, false>;
1366  using __node_iter_base = _Node_iterator_base<_Value, false>;
1367 
1368  _Local_iterator_base() : _M_bucket_count(-1) { }
1369 
1370  _Local_iterator_base(const __hash_code_base& __base,
1371  _Hash_node<_Value, false>* __p,
1372  std::size_t __bkt, std::size_t __bkt_count)
1373  : __node_iter_base(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1374  { _M_init(__base); }
1375 
1376  ~_Local_iterator_base()
1377  {
1378  if (_M_bucket_count != size_t(-1))
1379  _M_destroy();
1380  }
1381 
1382  _Local_iterator_base(const _Local_iterator_base& __iter)
1383  : __node_iter_base(__iter._M_cur), _M_bucket(__iter._M_bucket)
1384  , _M_bucket_count(__iter._M_bucket_count)
1385  {
1386  if (_M_bucket_count != size_t(-1))
1387  _M_init(*__iter._M_h());
1388  }
1389 
1390  _Local_iterator_base&
1391  operator=(const _Local_iterator_base& __iter)
1392  {
1393  if (_M_bucket_count != -1)
1394  _M_destroy();
1395  this->_M_cur = __iter._M_cur;
1396  _M_bucket = __iter._M_bucket;
1397  _M_bucket_count = __iter._M_bucket_count;
1398  if (_M_bucket_count != -1)
1399  _M_init(*__iter._M_h());
1400  return *this;
1401  }
1402 
1403  void
1404  _M_incr()
1405  {
1406  __node_iter_base::_M_incr();
1407  if (this->_M_cur)
1408  {
1409  std::size_t __bkt = this->_M_h()->_M_bucket_index(*this->_M_cur,
1410  _M_bucket_count);
1411  if (__bkt != _M_bucket)
1412  this->_M_cur = nullptr;
1413  }
1414  }
1415 
1416  std::size_t _M_bucket;
1417  std::size_t _M_bucket_count;
1418 
1419  void
1420  _M_init(const __hash_code_base& __base)
1421  { ::new(this->_M_h()) __hash_code_base(__base); }
1422 
1423  void
1424  _M_destroy() { this->_M_h()->~__hash_code_base(); }
1425 
1426  public:
1427  std::size_t
1428  _M_get_bucket() const { return _M_bucket; } // for debug mode
1429  };
1430 
1431  /// local iterators
1432  template<typename _Key, typename _Value, typename _ExtractKey,
1433  typename _Hash, typename _RangeHash, typename _Unused,
1434  bool __constant_iterators, bool __cache>
1436  : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1437  _Hash, _RangeHash, _Unused, __cache>
1438  {
1439  private:
1440  using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1441  _Hash, _RangeHash, _Unused, __cache>;
1442  using __hash_code_base = typename __base_type::__hash_code_base;
1443 
1444  public:
1445  typedef _Value value_type;
1446  typedef typename std::conditional<__constant_iterators,
1447  const value_type*, value_type*>::type
1448  pointer;
1449  typedef typename std::conditional<__constant_iterators,
1450  const value_type&, value_type&>::type
1451  reference;
1452  typedef std::ptrdiff_t difference_type;
1454 
1455  _Local_iterator() = default;
1456 
1457  _Local_iterator(const __hash_code_base& __base,
1459  std::size_t __bkt, std::size_t __bkt_count)
1460  : __base_type(__base, __n, __bkt, __bkt_count)
1461  { }
1462 
1463  reference
1464  operator*() const
1465  { return this->_M_cur->_M_v(); }
1466 
1467  pointer
1468  operator->() const
1469  { return this->_M_cur->_M_valptr(); }
1470 
1472  operator++()
1473  {
1474  this->_M_incr();
1475  return *this;
1476  }
1477 
1479  operator++(int)
1480  {
1481  _Local_iterator __tmp(*this);
1482  this->_M_incr();
1483  return __tmp;
1484  }
1485  };
1486 
1487  /// local const_iterators
1488  template<typename _Key, typename _Value, typename _ExtractKey,
1489  typename _Hash, typename _RangeHash, typename _Unused,
1490  bool __constant_iterators, bool __cache>
1492  : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1493  _Hash, _RangeHash, _Unused, __cache>
1494  {
1495  private:
1496  using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1497  _Hash, _RangeHash, _Unused, __cache>;
1498  using __hash_code_base = typename __base_type::__hash_code_base;
1499 
1500  public:
1501  typedef _Value value_type;
1502  typedef const value_type* pointer;
1503  typedef const value_type& reference;
1504  typedef std::ptrdiff_t difference_type;
1506 
1507  _Local_const_iterator() = default;
1508 
1509  _Local_const_iterator(const __hash_code_base& __base,
1511  std::size_t __bkt, std::size_t __bkt_count)
1512  : __base_type(__base, __n, __bkt, __bkt_count)
1513  { }
1514 
1515  _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
1516  _Hash, _RangeHash, _Unused,
1517  __constant_iterators,
1518  __cache>& __x)
1519  : __base_type(__x)
1520  { }
1521 
1522  reference
1523  operator*() const
1524  { return this->_M_cur->_M_v(); }
1525 
1526  pointer
1527  operator->() const
1528  { return this->_M_cur->_M_valptr(); }
1529 
1531  operator++()
1532  {
1533  this->_M_incr();
1534  return *this;
1535  }
1536 
1538  operator++(int)
1539  {
1540  _Local_const_iterator __tmp(*this);
1541  this->_M_incr();
1542  return __tmp;
1543  }
1544  };
1545 
1546  /**
1547  * Primary class template _Hashtable_base.
1548  *
1549  * Helper class adding management of _Equal functor to
1550  * _Hash_code_base type.
1551  *
1552  * Base class templates are:
1553  * - __detail::_Hash_code_base
1554  * - __detail::_Hashtable_ebo_helper
1555  */
1556  template<typename _Key, typename _Value, typename _ExtractKey,
1557  typename _Equal, typename _Hash, typename _RangeHash,
1558  typename _Unused, typename _Traits>
1559  struct _Hashtable_base
1560  : public _Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1561  _Unused, _Traits::__hash_cached::value>,
1562  private _Hashtable_ebo_helper<0, _Equal>
1563  {
1564  public:
1565  typedef _Key key_type;
1566  typedef _Value value_type;
1567  typedef _Equal key_equal;
1568  typedef std::size_t size_type;
1569  typedef std::ptrdiff_t difference_type;
1570 
1571  using __traits_type = _Traits;
1572  using __hash_cached = typename __traits_type::__hash_cached;
1573 
1574  using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1575  _Hash, _RangeHash, _Unused,
1576  __hash_cached::value>;
1577 
1578  using __hash_code = typename __hash_code_base::__hash_code;
1579 
1580  private:
1581  using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>;
1582 
1583  static bool
1584  _S_equals(__hash_code, const _Hash_node_code_cache<false>&)
1585  { return true; }
1586 
1587  static bool
1588  _S_node_equals(const _Hash_node_code_cache<false>&,
1589  const _Hash_node_code_cache<false>&)
1590  { return true; }
1591 
1592  static bool
1593  _S_equals(__hash_code __c, const _Hash_node_code_cache<true>& __n)
1594  { return __c == __n._M_hash_code; }
1595 
1596  static bool
1597  _S_node_equals(const _Hash_node_code_cache<true>& __lhn,
1598  const _Hash_node_code_cache<true>& __rhn)
1599  { return __lhn._M_hash_code == __rhn._M_hash_code; }
1600 
1601  protected:
1602  _Hashtable_base() = default;
1603  _Hashtable_base(const _Hash& __hash, const _Equal& __eq)
1604  : __hash_code_base(__hash), _EqualEBO(__eq)
1605  { }
1606 
1607  bool
1608  _M_equals(const _Key& __k, __hash_code __c,
1609  const _Hash_node_value<_Value, __hash_cached::value>& __n) const
1610  {
1611  static_assert(__is_invocable<const _Equal&, const _Key&, const _Key&>{},
1612  "key equality predicate must be invocable with two arguments of "
1613  "key type");
1614  return _S_equals(__c, __n) && _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1615  }
1616 
1617  template<typename _Kt>
1618  bool
1619  _M_equals_tr(const _Kt& __k, __hash_code __c,
1620  const _Hash_node_value<_Value,
1621  __hash_cached::value>& __n) const
1622  {
1623  static_assert(
1624  __is_invocable<const _Equal&, const _Kt&, const _Key&>{},
1625  "key equality predicate must be invocable with two arguments of "
1626  "key type");
1627  return _S_equals(__c, __n) && _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1628  }
1629 
1630  bool
1631  _M_node_equals(
1632  const _Hash_node_value<_Value, __hash_cached::value>& __lhn,
1633  const _Hash_node_value<_Value, __hash_cached::value>& __rhn) const
1634  {
1635  return _S_node_equals(__lhn, __rhn)
1636  && _M_eq()(_ExtractKey{}(__lhn._M_v()), _ExtractKey{}(__rhn._M_v()));
1637  }
1638 
1639  void
1640  _M_swap(_Hashtable_base& __x)
1641  {
1642  __hash_code_base::_M_swap(__x);
1643  std::swap(_EqualEBO::_M_get(), __x._EqualEBO::_M_get());
1644  }
1645 
1646  const _Equal&
1647  _M_eq() const { return _EqualEBO::_M_cget(); }
1648  };
1649 
1650  /**
1651  * Primary class template _Equality.
1652  *
1653  * This is for implementing equality comparison for unordered
1654  * containers, per N3068, by John Lakos and Pablo Halpern.
1655  * Algorithmically, we follow closely the reference implementations
1656  * therein.
1657  */
1658  template<typename _Key, typename _Value, typename _Alloc,
1659  typename _ExtractKey, typename _Equal,
1660  typename _Hash, typename _RangeHash, typename _Unused,
1661  typename _RehashPolicy, typename _Traits,
1662  bool _Unique_keys = _Traits::__unique_keys::value>
1663  struct _Equality;
1664 
1665  /// unordered_map and unordered_set specializations.
1666  template<typename _Key, typename _Value, typename _Alloc,
1667  typename _ExtractKey, typename _Equal,
1668  typename _Hash, typename _RangeHash, typename _Unused,
1669  typename _RehashPolicy, typename _Traits>
1670  struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1671  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
1672  {
1673  using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1674  _Hash, _RangeHash, _Unused,
1675  _RehashPolicy, _Traits>;
1676 
1677  bool
1678  _M_equal(const __hashtable&) const;
1679  };
1680 
1681  template<typename _Key, typename _Value, typename _Alloc,
1682  typename _ExtractKey, typename _Equal,
1683  typename _Hash, typename _RangeHash, typename _Unused,
1684  typename _RehashPolicy, typename _Traits>
1685  bool
1686  _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1687  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
1688  _M_equal(const __hashtable& __other) const
1689  {
1690  using __node_type = typename __hashtable::__node_type;
1691  const __hashtable* __this = static_cast<const __hashtable*>(this);
1692  if (__this->size() != __other.size())
1693  return false;
1694 
1695  for (auto __itx = __this->begin(); __itx != __this->end(); ++__itx)
1696  {
1697  std::size_t __ybkt = __other._M_bucket_index(*__itx._M_cur);
1698  auto __prev_n = __other._M_buckets[__ybkt];
1699  if (!__prev_n)
1700  return false;
1701 
1702  for (__node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);;
1703  __n = __n->_M_next())
1704  {
1705  if (__n->_M_v() == *__itx)
1706  break;
1707 
1708  if (!__n->_M_nxt
1709  || __other._M_bucket_index(*__n->_M_next()) != __ybkt)
1710  return false;
1711  }
1712  }
1713 
1714  return true;
1715  }
1716 
1717  /// unordered_multiset and unordered_multimap specializations.
1718  template<typename _Key, typename _Value, typename _Alloc,
1719  typename _ExtractKey, typename _Equal,
1720  typename _Hash, typename _RangeHash, typename _Unused,
1721  typename _RehashPolicy, typename _Traits>
1722  struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1723  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
1724  {
1725  using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1726  _Hash, _RangeHash, _Unused,
1727  _RehashPolicy, _Traits>;
1728 
1729  bool
1730  _M_equal(const __hashtable&) const;
1731  };
1732 
1733  template<typename _Key, typename _Value, typename _Alloc,
1734  typename _ExtractKey, typename _Equal,
1735  typename _Hash, typename _RangeHash, typename _Unused,
1736  typename _RehashPolicy, typename _Traits>
1737  bool
1738  _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1739  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>::
1740  _M_equal(const __hashtable& __other) const
1741  {
1742  using __node_type = typename __hashtable::__node_type;
1743  const __hashtable* __this = static_cast<const __hashtable*>(this);
1744  if (__this->size() != __other.size())
1745  return false;
1746 
1747  for (auto __itx = __this->begin(); __itx != __this->end();)
1748  {
1749  std::size_t __x_count = 1;
1750  auto __itx_end = __itx;
1751  for (++__itx_end; __itx_end != __this->end()
1752  && __this->key_eq()(_ExtractKey{}(*__itx),
1753  _ExtractKey{}(*__itx_end));
1754  ++__itx_end)
1755  ++__x_count;
1756 
1757  std::size_t __ybkt = __other._M_bucket_index(*__itx._M_cur);
1758  auto __y_prev_n = __other._M_buckets[__ybkt];
1759  if (!__y_prev_n)
1760  return false;
1761 
1762  __node_type* __y_n = static_cast<__node_type*>(__y_prev_n->_M_nxt);
1763  for (;;)
1764  {
1765  if (__this->key_eq()(_ExtractKey{}(__y_n->_M_v()),
1766  _ExtractKey{}(*__itx)))
1767  break;
1768 
1769  auto __y_ref_n = __y_n;
1770  for (__y_n = __y_n->_M_next(); __y_n; __y_n = __y_n->_M_next())
1771  if (!__other._M_node_equals(*__y_ref_n, *__y_n))
1772  break;
1773 
1774  if (!__y_n || __other._M_bucket_index(*__y_n) != __ybkt)
1775  return false;
1776  }
1777 
1778  typename __hashtable::const_iterator __ity(__y_n);
1779  for (auto __ity_end = __ity; __ity_end != __other.end(); ++__ity_end)
1780  if (--__x_count == 0)
1781  break;
1782 
1783  if (__x_count != 0)
1784  return false;
1785 
1786  if (!std::is_permutation(__itx, __itx_end, __ity))
1787  return false;
1788 
1789  __itx = __itx_end;
1790  }
1791  return true;
1792  }
1793 
1794  /**
1795  * This type deals with all allocation and keeps an allocator instance
1796  * through inheritance to benefit from EBO when possible.
1797  */
1798  template<typename _NodeAlloc>
1799  struct _Hashtable_alloc : private _Hashtable_ebo_helper<0, _NodeAlloc>
1800  {
1801  private:
1802  using __ebo_node_alloc = _Hashtable_ebo_helper<0, _NodeAlloc>;
1803  public:
1804  using __node_type = typename _NodeAlloc::value_type;
1805  using __node_alloc_type = _NodeAlloc;
1806  // Use __gnu_cxx to benefit from _S_always_equal and al.
1807  using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
1808 
1809  using __value_alloc_traits = typename __node_alloc_traits::template
1810  rebind_traits<typename __node_type::value_type>;
1811 
1812  using __node_ptr = __node_type*;
1813  using __node_base = _Hash_node_base;
1814  using __node_base_ptr = __node_base*;
1815  using __buckets_alloc_type =
1816  __alloc_rebind<__node_alloc_type, __node_base_ptr>;
1817  using __buckets_alloc_traits = std::allocator_traits<__buckets_alloc_type>;
1818  using __buckets_ptr = __node_base_ptr*;
1819 
1820  _Hashtable_alloc() = default;
1821  _Hashtable_alloc(const _Hashtable_alloc&) = default;
1822  _Hashtable_alloc(_Hashtable_alloc&&) = default;
1823 
1824  template<typename _Alloc>
1825  _Hashtable_alloc(_Alloc&& __a)
1826  : __ebo_node_alloc(std::forward<_Alloc>(__a))
1827  { }
1828 
1829  __node_alloc_type&
1830  _M_node_allocator()
1831  { return __ebo_node_alloc::_M_get(); }
1832 
1833  const __node_alloc_type&
1834  _M_node_allocator() const
1835  { return __ebo_node_alloc::_M_cget(); }
1836 
1837  // Allocate a node and construct an element within it.
1838  template<typename... _Args>
1839  __node_ptr
1840  _M_allocate_node(_Args&&... __args);
1841 
1842  // Destroy the element within a node and deallocate the node.
1843  void
1844  _M_deallocate_node(__node_ptr __n);
1845 
1846  // Deallocate a node.
1847  void
1848  _M_deallocate_node_ptr(__node_ptr __n);
1849 
1850  // Deallocate the linked list of nodes pointed to by __n.
1851  // The elements within the nodes are destroyed.
1852  void
1853  _M_deallocate_nodes(__node_ptr __n);
1854 
1855  __buckets_ptr
1856  _M_allocate_buckets(std::size_t __bkt_count);
1857 
1858  void
1859  _M_deallocate_buckets(__buckets_ptr, std::size_t __bkt_count);
1860  };
1861 
1862  // Definitions of class template _Hashtable_alloc's out-of-line member
1863  // functions.
1864  template<typename _NodeAlloc>
1865  template<typename... _Args>
1866  auto
1867  _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
1868  -> __node_ptr
1869  {
1870  auto __nptr = __node_alloc_traits::allocate(_M_node_allocator(), 1);
1871  __node_ptr __n = std::__to_address(__nptr);
1872  __try
1873  {
1874  ::new ((void*)__n) __node_type;
1875  __node_alloc_traits::construct(_M_node_allocator(),
1876  __n->_M_valptr(),
1877  std::forward<_Args>(__args)...);
1878  return __n;
1879  }
1880  __catch(...)
1881  {
1882  __node_alloc_traits::deallocate(_M_node_allocator(), __nptr, 1);
1883  __throw_exception_again;
1884  }
1885  }
1886 
1887  template<typename _NodeAlloc>
1888  void
1889  _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_ptr __n)
1890  {
1891  __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
1892  _M_deallocate_node_ptr(__n);
1893  }
1894 
1895  template<typename _NodeAlloc>
1896  void
1897  _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node_ptr(__node_ptr __n)
1898  {
1899  typedef typename __node_alloc_traits::pointer _Ptr;
1900  auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
1901  __n->~__node_type();
1902  __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
1903  }
1904 
1905  template<typename _NodeAlloc>
1906  void
1907  _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_ptr __n)
1908  {
1909  while (__n)
1910  {
1911  __node_ptr __tmp = __n;
1912  __n = __n->_M_next();
1913  _M_deallocate_node(__tmp);
1914  }
1915  }
1916 
1917  template<typename _NodeAlloc>
1918  auto
1919  _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(std::size_t __bkt_count)
1920  -> __buckets_ptr
1921  {
1922  __buckets_alloc_type __alloc(_M_node_allocator());
1923 
1924  auto __ptr = __buckets_alloc_traits::allocate(__alloc, __bkt_count);
1925  __buckets_ptr __p = std::__to_address(__ptr);
1926  __builtin_memset(__p, 0, __bkt_count * sizeof(__node_base_ptr));
1927  return __p;
1928  }
1929 
1930  template<typename _NodeAlloc>
1931  void
1932  _Hashtable_alloc<_NodeAlloc>::
1933  _M_deallocate_buckets(__buckets_ptr __bkts,
1934  std::size_t __bkt_count)
1935  {
1936  typedef typename __buckets_alloc_traits::pointer _Ptr;
1937  auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
1938  __buckets_alloc_type __alloc(_M_node_allocator());
1939  __buckets_alloc_traits::deallocate(__alloc, __ptr, __bkt_count);
1940  }
1941 
1942  ///@} hashtable-detail
1943 } // namespace __detail
1944 _GLIBCXX_END_NAMESPACE_VERSION
1945 } // namespace std
1946 
1947 #endif // _HASHTABLE_POLICY_H
__numeric_traits_integer< _Tp > __int_traits
Convenience alias for __numeric_traits<integer-type>.
initializer_list
Traits class for iterators.
integral_constant
Definition: type_traits:57
Node iterators, used to iterate through all the hashtable.
Uniform interface to all pointer-like types.
Definition: ptr_traits.h:83
Marking input iterators.
Define a member typedef type only if a boolean constant is true.
Definition: type_traits:2142
Range hashing function assuming that second arg is a power of 2.
constexpr iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
Default range hashing function: use division to fold a large number into the range [0...
Base class for node iterators.
Struct holding two objects of arbitrary type.
Definition: stl_pair.h:211
Forward iterators support a superset of input iterator operations.
constexpr piecewise_construct_t piecewise_construct
Tag for piecewise construction of std::pair objects.
Definition: stl_pair.h:83
constexpr tuple< _Elements &&... > forward_as_tuple(_Elements &&... __args) noexcept
std::forward_as_tuple
Definition: tuple:1606
Define a member typedef type to one of two argument types.
Definition: type_traits:92
Uniform interface to all allocator types.
tuple_element
Definition: array:442
Default value for rehash policy. Bucket size is (usually) the smallest prime that keeps the load fact...
is_constructible
Definition: type_traits:911
Node const_iterators, used to iterate through all the hashtable.
element_type * operator->() const
Smart pointer dereferencing.
Definition: auto_ptr.h:186
std::size_t __clp2(std::size_t __n) noexcept
Compute closest power of 2 not less than __n.
is_empty
Definition: type_traits:720
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition: type_traits:75
constexpr _Iterator __base(_Iterator __it)
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
constexpr complex< _Tp > operator*(const complex< _Tp > &__x, const complex< _Tp > &__y)
Return new complex value x times y.
Definition: complex:392
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition: move.h:77
ISO C++ entities toplevel namespace is std.
auto_ptr & operator=(auto_ptr &__a)
auto_ptr assignment operator.
Definition: auto_ptr.h:128
Uniform interface to C++98 and C++11 allocators.
Default ranged hash function H. In principle it should be a function object composed from objects of ...
Primary class template, tuple.
Definition: tuple:57
Rehash policy providing power of 2 bucket numbers. Avoids modulo operations.