libstdc++
hashtable_policy.h
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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 /// @cond undocumented
42 
43  template<typename _Key, typename _Value, typename _Alloc,
44  typename _ExtractKey, typename _Equal,
45  typename _Hash, typename _RangeHash, typename _Unused,
46  typename _RehashPolicy, typename _Traits>
47  class _Hashtable;
48 
49 namespace __detail
50 {
51  /**
52  * @defgroup hashtable-detail Base and Implementation Classes
53  * @ingroup unordered_associative_containers
54  * @{
55  */
56  template<typename _Key, typename _Value, typename _ExtractKey,
57  typename _Equal, typename _Hash, typename _RangeHash,
58  typename _Unused, typename _Traits>
59  struct _Hashtable_base;
60 
61  // Helper function: return distance(first, last) for forward
62  // iterators, or 0/1 for input iterators.
63  template<class _Iterator>
65  __distance_fw(_Iterator __first, _Iterator __last,
67  { return __first != __last ? 1 : 0; }
68 
69  template<class _Iterator>
71  __distance_fw(_Iterator __first, _Iterator __last,
73  { return std::distance(__first, __last); }
74 
75  template<class _Iterator>
77  __distance_fw(_Iterator __first, _Iterator __last)
78  { return __distance_fw(__first, __last,
79  std::__iterator_category(__first)); }
80 
81  struct _Identity
82  {
83  template<typename _Tp>
84  _Tp&&
85  operator()(_Tp&& __x) const noexcept
86  { return std::forward<_Tp>(__x); }
87  };
88 
89  struct _Select1st
90  {
91  template<typename _Tp>
92  auto
93  operator()(_Tp&& __x) const noexcept
94  -> decltype(std::get<0>(std::forward<_Tp>(__x)))
95  { return std::get<0>(std::forward<_Tp>(__x)); }
96  };
97 
98  template<typename _NodeAlloc>
99  struct _Hashtable_alloc;
100 
101  // Functor recycling a pool of nodes and using allocation once the pool is
102  // empty.
103  template<typename _NodeAlloc>
104  struct _ReuseOrAllocNode
105  {
106  private:
107  using __node_alloc_type = _NodeAlloc;
108  using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
109  using __node_alloc_traits =
110  typename __hashtable_alloc::__node_alloc_traits;
111  using __node_type = typename __hashtable_alloc::__node_type;
112 
113  public:
114  _ReuseOrAllocNode(__node_type* __nodes, __hashtable_alloc& __h)
115  : _M_nodes(__nodes), _M_h(__h) { }
116  _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;
117 
118  ~_ReuseOrAllocNode()
119  { _M_h._M_deallocate_nodes(_M_nodes); }
120 
121  template<typename _Arg>
122  __node_type*
123  operator()(_Arg&& __arg) const
124  {
125  if (_M_nodes)
126  {
127  __node_type* __node = _M_nodes;
128  _M_nodes = _M_nodes->_M_next();
129  __node->_M_nxt = nullptr;
130  auto& __a = _M_h._M_node_allocator();
131  __node_alloc_traits::destroy(__a, __node->_M_valptr());
132  __try
133  {
134  __node_alloc_traits::construct(__a, __node->_M_valptr(),
135  std::forward<_Arg>(__arg));
136  }
137  __catch(...)
138  {
139  _M_h._M_deallocate_node_ptr(__node);
140  __throw_exception_again;
141  }
142  return __node;
143  }
144  return _M_h._M_allocate_node(std::forward<_Arg>(__arg));
145  }
146 
147  private:
148  mutable __node_type* _M_nodes;
149  __hashtable_alloc& _M_h;
150  };
151 
152  // Functor similar to the previous one but without any pool of nodes to
153  // recycle.
154  template<typename _NodeAlloc>
155  struct _AllocNode
156  {
157  private:
158  using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
159  using __node_type = typename __hashtable_alloc::__node_type;
160 
161  public:
162  _AllocNode(__hashtable_alloc& __h)
163  : _M_h(__h) { }
164 
165  template<typename _Arg>
166  __node_type*
167  operator()(_Arg&& __arg) const
168  { return _M_h._M_allocate_node(std::forward<_Arg>(__arg)); }
169 
170  private:
171  __hashtable_alloc& _M_h;
172  };
173 
174  // Auxiliary types used for all instantiations of _Hashtable nodes
175  // and iterators.
176 
177  /**
178  * struct _Hashtable_traits
179  *
180  * Important traits for hash tables.
181  *
182  * @tparam _Cache_hash_code Boolean value. True if the value of
183  * the hash function is stored along with the value. This is a
184  * time-space tradeoff. Storing it may improve lookup speed by
185  * reducing the number of times we need to call the _Hash or _Equal
186  * functors.
187  *
188  * @tparam _Constant_iterators Boolean value. True if iterator and
189  * const_iterator are both constant iterator types. This is true
190  * for unordered_set and unordered_multiset, false for
191  * unordered_map and unordered_multimap.
192  *
193  * @tparam _Unique_keys Boolean value. True if the return value
194  * of _Hashtable::count(k) is always at most one, false if it may
195  * be an arbitrary number. This is true for unordered_set and
196  * unordered_map, false for unordered_multiset and
197  * unordered_multimap.
198  */
199  template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
200  struct _Hashtable_traits
201  {
202  using __hash_cached = __bool_constant<_Cache_hash_code>;
203  using __constant_iterators = __bool_constant<_Constant_iterators>;
204  using __unique_keys = __bool_constant<_Unique_keys>;
205  };
206 
207  /**
208  * struct _Hash_node_base
209  *
210  * Nodes, used to wrap elements stored in the hash table. A policy
211  * template parameter of class template _Hashtable controls whether
212  * nodes also store a hash code. In some cases (e.g. strings) this
213  * may be a performance win.
214  */
215  struct _Hash_node_base
216  {
217  _Hash_node_base* _M_nxt;
218 
219  _Hash_node_base() noexcept : _M_nxt() { }
220 
221  _Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
222  };
223 
224  /**
225  * struct _Hash_node_value_base
226  *
227  * Node type with the value to store.
228  */
229  template<typename _Value>
230  struct _Hash_node_value_base
231  {
232  typedef _Value value_type;
233 
234  __gnu_cxx::__aligned_buffer<_Value> _M_storage;
235 
236  _Value*
237  _M_valptr() noexcept
238  { return _M_storage._M_ptr(); }
239 
240  const _Value*
241  _M_valptr() const noexcept
242  { return _M_storage._M_ptr(); }
243 
244  _Value&
245  _M_v() noexcept
246  { return *_M_valptr(); }
247 
248  const _Value&
249  _M_v() const noexcept
250  { return *_M_valptr(); }
251  };
252 
253  /**
254  * Primary template struct _Hash_node_code_cache.
255  */
256  template<bool _Cache_hash_code>
257  struct _Hash_node_code_cache
258  { };
259 
260  /**
261  * Specialization for node with cache, struct _Hash_node_code_cache.
262  */
263  template<>
264  struct _Hash_node_code_cache<true>
265  { std::size_t _M_hash_code; };
266 
267  template<typename _Value, bool _Cache_hash_code>
268  struct _Hash_node_value
269  : _Hash_node_value_base<_Value>
270  , _Hash_node_code_cache<_Cache_hash_code>
271  { };
272 
273  /**
274  * Primary template struct _Hash_node.
275  */
276  template<typename _Value, bool _Cache_hash_code>
277  struct _Hash_node
278  : _Hash_node_base
279  , _Hash_node_value<_Value, _Cache_hash_code>
280  {
281  _Hash_node*
282  _M_next() const noexcept
283  { return static_cast<_Hash_node*>(this->_M_nxt); }
284  };
285 
286  /// Base class for node iterators.
287  template<typename _Value, bool _Cache_hash_code>
288  struct _Node_iterator_base
289  {
290  using __node_type = _Hash_node<_Value, _Cache_hash_code>;
291 
292  __node_type* _M_cur;
293 
294  _Node_iterator_base() : _M_cur(nullptr) { }
295  _Node_iterator_base(__node_type* __p) noexcept
296  : _M_cur(__p) { }
297 
298  void
299  _M_incr() noexcept
300  { _M_cur = _M_cur->_M_next(); }
301 
302  friend bool
303  operator==(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
304  noexcept
305  { return __x._M_cur == __y._M_cur; }
306 
307 #if __cpp_impl_three_way_comparison < 201907L
308  friend bool
309  operator!=(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
310  noexcept
311  { return __x._M_cur != __y._M_cur; }
312 #endif
313  };
314 
315  /// Node iterators, used to iterate through all the hashtable.
316  template<typename _Value, bool __constant_iterators, bool __cache>
317  struct _Node_iterator
318  : public _Node_iterator_base<_Value, __cache>
319  {
320  private:
321  using __base_type = _Node_iterator_base<_Value, __cache>;
322  using __node_type = typename __base_type::__node_type;
323 
324  public:
325  typedef _Value value_type;
326  typedef std::ptrdiff_t difference_type;
327  typedef std::forward_iterator_tag iterator_category;
328 
329  using pointer = typename std::conditional<__constant_iterators,
330  const value_type*, value_type*>::type;
331 
332  using reference = typename std::conditional<__constant_iterators,
333  const value_type&, value_type&>::type;
334 
335  _Node_iterator() = default;
336 
337  explicit
338  _Node_iterator(__node_type* __p) noexcept
339  : __base_type(__p) { }
340 
341  reference
342  operator*() const noexcept
343  { return this->_M_cur->_M_v(); }
344 
345  pointer
346  operator->() const noexcept
347  { return this->_M_cur->_M_valptr(); }
348 
349  _Node_iterator&
350  operator++() noexcept
351  {
352  this->_M_incr();
353  return *this;
354  }
355 
356  _Node_iterator
357  operator++(int) noexcept
358  {
359  _Node_iterator __tmp(*this);
360  this->_M_incr();
361  return __tmp;
362  }
363  };
364 
365  /// Node const_iterators, used to iterate through all the hashtable.
366  template<typename _Value, bool __constant_iterators, bool __cache>
367  struct _Node_const_iterator
368  : public _Node_iterator_base<_Value, __cache>
369  {
370  private:
371  using __base_type = _Node_iterator_base<_Value, __cache>;
372  using __node_type = typename __base_type::__node_type;
373 
374  public:
375  typedef _Value value_type;
376  typedef std::ptrdiff_t difference_type;
377  typedef std::forward_iterator_tag iterator_category;
378 
379  typedef const value_type* pointer;
380  typedef const value_type& reference;
381 
382  _Node_const_iterator() = default;
383 
384  explicit
385  _Node_const_iterator(__node_type* __p) noexcept
386  : __base_type(__p) { }
387 
388  _Node_const_iterator(const _Node_iterator<_Value, __constant_iterators,
389  __cache>& __x) noexcept
390  : __base_type(__x._M_cur) { }
391 
392  reference
393  operator*() const noexcept
394  { return this->_M_cur->_M_v(); }
395 
396  pointer
397  operator->() const noexcept
398  { return this->_M_cur->_M_valptr(); }
399 
400  _Node_const_iterator&
401  operator++() noexcept
402  {
403  this->_M_incr();
404  return *this;
405  }
406 
407  _Node_const_iterator
408  operator++(int) noexcept
409  {
410  _Node_const_iterator __tmp(*this);
411  this->_M_incr();
412  return __tmp;
413  }
414  };
415 
416  // Many of class template _Hashtable's template parameters are policy
417  // classes. These are defaults for the policies.
418 
419  /// Default range hashing function: use division to fold a large number
420  /// into the range [0, N).
421  struct _Mod_range_hashing
422  {
423  typedef std::size_t first_argument_type;
424  typedef std::size_t second_argument_type;
425  typedef std::size_t result_type;
426 
427  result_type
428  operator()(first_argument_type __num,
429  second_argument_type __den) const noexcept
430  { return __num % __den; }
431  };
432 
433  /// Default ranged hash function H. In principle it should be a
434  /// function object composed from objects of type H1 and H2 such that
435  /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
436  /// h1 and h2. So instead we'll just use a tag to tell class template
437  /// hashtable to do that composition.
438  struct _Default_ranged_hash { };
439 
440  /// Default value for rehash policy. Bucket size is (usually) the
441  /// smallest prime that keeps the load factor small enough.
442  struct _Prime_rehash_policy
443  {
444  using __has_load_factor = true_type;
445 
446  _Prime_rehash_policy(float __z = 1.0) noexcept
447  : _M_max_load_factor(__z), _M_next_resize(0) { }
448 
449  float
450  max_load_factor() const noexcept
451  { return _M_max_load_factor; }
452 
453  // Return a bucket size no smaller than n.
454  std::size_t
455  _M_next_bkt(std::size_t __n) const;
456 
457  // Return a bucket count appropriate for n elements
458  std::size_t
459  _M_bkt_for_elements(std::size_t __n) const
460  { return __builtin_ceil(__n / (double)_M_max_load_factor); }
461 
462  // __n_bkt is current bucket count, __n_elt is current element count,
463  // and __n_ins is number of elements to be inserted. Do we need to
464  // increase bucket count? If so, return make_pair(true, n), where n
465  // is the new bucket count. If not, return make_pair(false, 0).
467  _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
468  std::size_t __n_ins) const;
469 
470  typedef std::size_t _State;
471 
472  _State
473  _M_state() const
474  { return _M_next_resize; }
475 
476  void
477  _M_reset() noexcept
478  { _M_next_resize = 0; }
479 
480  void
481  _M_reset(_State __state)
482  { _M_next_resize = __state; }
483 
484  static const std::size_t _S_growth_factor = 2;
485 
486  float _M_max_load_factor;
487  mutable std::size_t _M_next_resize;
488  };
489 
490  /// Range hashing function assuming that second arg is a power of 2.
491  struct _Mask_range_hashing
492  {
493  typedef std::size_t first_argument_type;
494  typedef std::size_t second_argument_type;
495  typedef std::size_t result_type;
496 
497  result_type
498  operator()(first_argument_type __num,
499  second_argument_type __den) const noexcept
500  { return __num & (__den - 1); }
501  };
502 
503  /// Compute closest power of 2 not less than __n
504  inline std::size_t
505  __clp2(std::size_t __n) noexcept
506  {
508  // Equivalent to return __n ? std::bit_ceil(__n) : 0;
509  if (__n < 2)
510  return __n;
511  const unsigned __lz = sizeof(size_t) > sizeof(long)
512  ? __builtin_clzll(__n - 1ull)
513  : __builtin_clzl(__n - 1ul);
514  // Doing two shifts avoids undefined behaviour when __lz == 0.
515  return (size_t(1) << (__int_traits<size_t>::__digits - __lz - 1)) << 1;
516  }
517 
518  /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
519  /// operations.
520  struct _Power2_rehash_policy
521  {
522  using __has_load_factor = true_type;
523 
524  _Power2_rehash_policy(float __z = 1.0) noexcept
525  : _M_max_load_factor(__z), _M_next_resize(0) { }
526 
527  float
528  max_load_factor() const noexcept
529  { return _M_max_load_factor; }
530 
531  // Return a bucket size no smaller than n (as long as n is not above the
532  // highest power of 2).
533  std::size_t
534  _M_next_bkt(std::size_t __n) noexcept
535  {
536  if (__n == 0)
537  // Special case on container 1st initialization with 0 bucket count
538  // hint. We keep _M_next_resize to 0 to make sure that next time we
539  // want to add an element allocation will take place.
540  return 1;
541 
542  const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
543  const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
544  std::size_t __res = __clp2(__n);
545 
546  if (__res == 0)
547  __res = __max_bkt;
548  else if (__res == 1)
549  // If __res is 1 we force it to 2 to make sure there will be an
550  // allocation so that nothing need to be stored in the initial
551  // single bucket
552  __res = 2;
553 
554  if (__res == __max_bkt)
555  // Set next resize to the max value so that we never try to rehash again
556  // as we already reach the biggest possible bucket number.
557  // Note that it might result in max_load_factor not being respected.
558  _M_next_resize = size_t(-1);
559  else
560  _M_next_resize
561  = __builtin_floor(__res * (double)_M_max_load_factor);
562 
563  return __res;
564  }
565 
566  // Return a bucket count appropriate for n elements
567  std::size_t
568  _M_bkt_for_elements(std::size_t __n) const noexcept
569  { return __builtin_ceil(__n / (double)_M_max_load_factor); }
570 
571  // __n_bkt is current bucket count, __n_elt is current element count,
572  // and __n_ins is number of elements to be inserted. Do we need to
573  // increase bucket count? If so, return make_pair(true, n), where n
574  // is the new bucket count. If not, return make_pair(false, 0).
576  _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
577  std::size_t __n_ins) noexcept
578  {
579  if (__n_elt + __n_ins > _M_next_resize)
580  {
581  // If _M_next_resize is 0 it means that we have nothing allocated so
582  // far and that we start inserting elements. In this case we start
583  // with an initial bucket size of 11.
584  double __min_bkts
585  = std::max<std::size_t>(__n_elt + __n_ins, _M_next_resize ? 0 : 11)
586  / (double)_M_max_load_factor;
587  if (__min_bkts >= __n_bkt)
588  return { true,
589  _M_next_bkt(std::max<std::size_t>(__builtin_floor(__min_bkts) + 1,
590  __n_bkt * _S_growth_factor)) };
591 
592  _M_next_resize
593  = __builtin_floor(__n_bkt * (double)_M_max_load_factor);
594  return { false, 0 };
595  }
596  else
597  return { false, 0 };
598  }
599 
600  typedef std::size_t _State;
601 
602  _State
603  _M_state() const noexcept
604  { return _M_next_resize; }
605 
606  void
607  _M_reset() noexcept
608  { _M_next_resize = 0; }
609 
610  void
611  _M_reset(_State __state) noexcept
612  { _M_next_resize = __state; }
613 
614  static const std::size_t _S_growth_factor = 2;
615 
616  float _M_max_load_factor;
617  std::size_t _M_next_resize;
618  };
619 
620  // Base classes for std::_Hashtable. We define these base classes
621  // because in some cases we want to do different things depending on
622  // the value of a policy class. In some cases the policy class
623  // affects which member functions and nested typedefs are defined;
624  // we handle that by specializing base class templates. Several of
625  // the base class templates need to access other members of class
626  // template _Hashtable, so we use a variant of the "Curiously
627  // Recurring Template Pattern" (CRTP) technique.
628 
629  /**
630  * Primary class template _Map_base.
631  *
632  * If the hashtable has a value type of the form pair<T1, T2> and a
633  * key extraction policy (_ExtractKey) that returns the first part
634  * of the pair, the hashtable gets a mapped_type typedef. If it
635  * satisfies those criteria and also has unique keys, then it also
636  * gets an operator[].
637  */
638  template<typename _Key, typename _Value, typename _Alloc,
639  typename _ExtractKey, typename _Equal,
640  typename _Hash, typename _RangeHash, typename _Unused,
641  typename _RehashPolicy, typename _Traits,
642  bool _Unique_keys = _Traits::__unique_keys::value>
643  struct _Map_base { };
644 
645  /// Partial specialization, __unique_keys set to false.
646  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
647  typename _Hash, typename _RangeHash, typename _Unused,
648  typename _RehashPolicy, typename _Traits>
649  struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
650  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
651  {
652  using mapped_type = typename std::tuple_element<1, _Pair>::type;
653  };
654 
655  /// Partial specialization, __unique_keys set to true.
656  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
657  typename _Hash, typename _RangeHash, typename _Unused,
658  typename _RehashPolicy, typename _Traits>
659  struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
660  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
661  {
662  private:
663  using __hashtable_base = _Hashtable_base<_Key, _Pair, _Select1st, _Equal,
664  _Hash, _RangeHash, _Unused,
665  _Traits>;
666 
667  using __hashtable = _Hashtable<_Key, _Pair, _Alloc, _Select1st, _Equal,
668  _Hash, _RangeHash,
669  _Unused, _RehashPolicy, _Traits>;
670 
671  using __hash_code = typename __hashtable_base::__hash_code;
672 
673  public:
674  using key_type = typename __hashtable_base::key_type;
675  using mapped_type = typename std::tuple_element<1, _Pair>::type;
676 
677  mapped_type&
678  operator[](const key_type& __k);
679 
680  mapped_type&
681  operator[](key_type&& __k);
682 
683  // _GLIBCXX_RESOLVE_LIB_DEFECTS
684  // DR 761. unordered_map needs an at() member function.
685  mapped_type&
686  at(const key_type& __k);
687 
688  const mapped_type&
689  at(const key_type& __k) const;
690  };
691 
692  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
693  typename _Hash, typename _RangeHash, typename _Unused,
694  typename _RehashPolicy, typename _Traits>
695  auto
696  _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
697  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
698  operator[](const key_type& __k)
699  -> mapped_type&
700  {
701  __hashtable* __h = static_cast<__hashtable*>(this);
702  __hash_code __code = __h->_M_hash_code(__k);
703  std::size_t __bkt = __h->_M_bucket_index(__code);
704  if (auto __node = __h->_M_find_node(__bkt, __k, __code))
705  return __node->_M_v().second;
706 
707  typename __hashtable::_Scoped_node __node {
708  __h,
711  std::tuple<>()
712  };
713  auto __pos
714  = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
715  __node._M_node = nullptr;
716  return __pos->second;
717  }
718 
719  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
720  typename _Hash, typename _RangeHash, typename _Unused,
721  typename _RehashPolicy, typename _Traits>
722  auto
723  _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
724  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
725  operator[](key_type&& __k)
726  -> mapped_type&
727  {
728  __hashtable* __h = static_cast<__hashtable*>(this);
729  __hash_code __code = __h->_M_hash_code(__k);
730  std::size_t __bkt = __h->_M_bucket_index(__code);
731  if (auto __node = __h->_M_find_node(__bkt, __k, __code))
732  return __node->_M_v().second;
733 
734  typename __hashtable::_Scoped_node __node {
735  __h,
738  std::tuple<>()
739  };
740  auto __pos
741  = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
742  __node._M_node = nullptr;
743  return __pos->second;
744  }
745 
746  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
747  typename _Hash, typename _RangeHash, typename _Unused,
748  typename _RehashPolicy, typename _Traits>
749  auto
750  _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
751  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
752  at(const key_type& __k)
753  -> mapped_type&
754  {
755  __hashtable* __h = static_cast<__hashtable*>(this);
756  auto __ite = __h->find(__k);
757 
758  if (!__ite._M_cur)
759  __throw_out_of_range(__N("_Map_base::at"));
760  return __ite->second;
761  }
762 
763  template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
764  typename _Hash, typename _RangeHash, typename _Unused,
765  typename _RehashPolicy, typename _Traits>
766  auto
767  _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
768  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
769  at(const key_type& __k) const
770  -> const mapped_type&
771  {
772  const __hashtable* __h = static_cast<const __hashtable*>(this);
773  auto __ite = __h->find(__k);
774 
775  if (!__ite._M_cur)
776  __throw_out_of_range(__N("_Map_base::at"));
777  return __ite->second;
778  }
779 
780  /**
781  * Primary class template _Insert_base.
782  *
783  * Defines @c insert member functions appropriate to all _Hashtables.
784  */
785  template<typename _Key, typename _Value, typename _Alloc,
786  typename _ExtractKey, typename _Equal,
787  typename _Hash, typename _RangeHash, typename _Unused,
788  typename _RehashPolicy, typename _Traits>
789  struct _Insert_base
790  {
791  protected:
792  using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
793  _Equal, _Hash, _RangeHash,
794  _Unused, _Traits>;
795 
796  using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
797  _Hash, _RangeHash,
798  _Unused, _RehashPolicy, _Traits>;
799 
800  using __hash_cached = typename _Traits::__hash_cached;
801  using __constant_iterators = typename _Traits::__constant_iterators;
802 
803  using __hashtable_alloc = _Hashtable_alloc<
804  __alloc_rebind<_Alloc, _Hash_node<_Value,
805  __hash_cached::value>>>;
806 
807  using value_type = typename __hashtable_base::value_type;
808  using size_type = typename __hashtable_base::size_type;
809 
810  using __unique_keys = typename _Traits::__unique_keys;
811  using __node_alloc_type = typename __hashtable_alloc::__node_alloc_type;
812  using __node_gen_type = _AllocNode<__node_alloc_type>;
813 
814  __hashtable&
815  _M_conjure_hashtable()
816  { return *(static_cast<__hashtable*>(this)); }
817 
818  template<typename _InputIterator, typename _NodeGetter>
819  void
820  _M_insert_range(_InputIterator __first, _InputIterator __last,
821  const _NodeGetter&, true_type __uks);
822 
823  template<typename _InputIterator, typename _NodeGetter>
824  void
825  _M_insert_range(_InputIterator __first, _InputIterator __last,
826  const _NodeGetter&, false_type __uks);
827 
828  public:
829  using iterator = _Node_iterator<_Value, __constant_iterators::value,
830  __hash_cached::value>;
831 
832  using const_iterator = _Node_const_iterator<_Value, __constant_iterators::value,
833  __hash_cached::value>;
834 
835  using __ireturn_type = typename std::conditional<__unique_keys::value,
837  iterator>::type;
838 
839  __ireturn_type
840  insert(const value_type& __v)
841  {
842  __hashtable& __h = _M_conjure_hashtable();
843  __node_gen_type __node_gen(__h);
844  return __h._M_insert(__v, __node_gen, __unique_keys{});
845  }
846 
847  iterator
848  insert(const_iterator __hint, const value_type& __v)
849  {
850  __hashtable& __h = _M_conjure_hashtable();
851  __node_gen_type __node_gen(__h);
852  return __h._M_insert(__hint, __v, __node_gen, __unique_keys{});
853  }
854 
855  template<typename _KType, typename... _Args>
857  try_emplace(const_iterator, _KType&& __k, _Args&&... __args)
858  {
859  __hashtable& __h = _M_conjure_hashtable();
860  auto __code = __h._M_hash_code(__k);
861  std::size_t __bkt = __h._M_bucket_index(__code);
862  if (auto __node = __h._M_find_node(__bkt, __k, __code))
863  return { iterator(__node), false };
864 
865  typename __hashtable::_Scoped_node __node {
866  &__h,
868  std::forward_as_tuple(std::forward<_KType>(__k)),
869  std::forward_as_tuple(std::forward<_Args>(__args)...)
870  };
871  auto __it
872  = __h._M_insert_unique_node(__bkt, __code, __node._M_node);
873  __node._M_node = nullptr;
874  return { __it, true };
875  }
876 
877  void
878  insert(initializer_list<value_type> __l)
879  { this->insert(__l.begin(), __l.end()); }
880 
881  template<typename _InputIterator>
882  void
883  insert(_InputIterator __first, _InputIterator __last)
884  {
885  __hashtable& __h = _M_conjure_hashtable();
886  __node_gen_type __node_gen(__h);
887  return _M_insert_range(__first, __last, __node_gen, __unique_keys{});
888  }
889  };
890 
891  template<typename _Key, typename _Value, typename _Alloc,
892  typename _ExtractKey, typename _Equal,
893  typename _Hash, typename _RangeHash, typename _Unused,
894  typename _RehashPolicy, typename _Traits>
895  template<typename _InputIterator, typename _NodeGetter>
896  void
897  _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
898  _Hash, _RangeHash, _Unused,
899  _RehashPolicy, _Traits>::
900  _M_insert_range(_InputIterator __first, _InputIterator __last,
901  const _NodeGetter& __node_gen, true_type __uks)
902  {
903  __hashtable& __h = _M_conjure_hashtable();
904  for (; __first != __last; ++__first)
905  __h._M_insert(*__first, __node_gen, __uks);
906  }
907 
908  template<typename _Key, typename _Value, typename _Alloc,
909  typename _ExtractKey, typename _Equal,
910  typename _Hash, typename _RangeHash, typename _Unused,
911  typename _RehashPolicy, typename _Traits>
912  template<typename _InputIterator, typename _NodeGetter>
913  void
914  _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
915  _Hash, _RangeHash, _Unused,
916  _RehashPolicy, _Traits>::
917  _M_insert_range(_InputIterator __first, _InputIterator __last,
918  const _NodeGetter& __node_gen, false_type __uks)
919  {
920  using __rehash_type = typename __hashtable::__rehash_type;
921  using __rehash_state = typename __hashtable::__rehash_state;
922  using pair_type = std::pair<bool, std::size_t>;
923 
924  size_type __n_elt = __detail::__distance_fw(__first, __last);
925  if (__n_elt == 0)
926  return;
927 
928  __hashtable& __h = _M_conjure_hashtable();
929  __rehash_type& __rehash = __h._M_rehash_policy;
930  const __rehash_state& __saved_state = __rehash._M_state();
931  pair_type __do_rehash = __rehash._M_need_rehash(__h._M_bucket_count,
932  __h._M_element_count,
933  __n_elt);
934 
935  if (__do_rehash.first)
936  __h._M_rehash(__do_rehash.second, __saved_state);
937 
938  for (; __first != __last; ++__first)
939  __h._M_insert(*__first, __node_gen, __uks);
940  }
941 
942  /**
943  * Primary class template _Insert.
944  *
945  * Defines @c insert member functions that depend on _Hashtable policies,
946  * via partial specializations.
947  */
948  template<typename _Key, typename _Value, typename _Alloc,
949  typename _ExtractKey, typename _Equal,
950  typename _Hash, typename _RangeHash, typename _Unused,
951  typename _RehashPolicy, typename _Traits,
952  bool _Constant_iterators = _Traits::__constant_iterators::value>
953  struct _Insert;
954 
955  /// Specialization.
956  template<typename _Key, typename _Value, typename _Alloc,
957  typename _ExtractKey, typename _Equal,
958  typename _Hash, typename _RangeHash, typename _Unused,
959  typename _RehashPolicy, typename _Traits>
960  struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
961  _Hash, _RangeHash, _Unused,
962  _RehashPolicy, _Traits, true>
963  : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
964  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>
965  {
966  using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
967  _Equal, _Hash, _RangeHash, _Unused,
968  _RehashPolicy, _Traits>;
969 
970  using value_type = typename __base_type::value_type;
971  using iterator = typename __base_type::iterator;
972  using const_iterator = typename __base_type::const_iterator;
973  using __ireturn_type = typename __base_type::__ireturn_type;
974 
975  using __unique_keys = typename __base_type::__unique_keys;
976  using __hashtable = typename __base_type::__hashtable;
977  using __node_gen_type = typename __base_type::__node_gen_type;
978 
979  using __base_type::insert;
980 
981  __ireturn_type
982  insert(value_type&& __v)
983  {
984  __hashtable& __h = this->_M_conjure_hashtable();
985  __node_gen_type __node_gen(__h);
986  return __h._M_insert(std::move(__v), __node_gen, __unique_keys{});
987  }
988 
989  iterator
990  insert(const_iterator __hint, value_type&& __v)
991  {
992  __hashtable& __h = this->_M_conjure_hashtable();
993  __node_gen_type __node_gen(__h);
994  return __h._M_insert(__hint, std::move(__v), __node_gen,
995  __unique_keys{});
996  }
997  };
998 
999  /// Specialization.
1000  template<typename _Key, typename _Value, typename _Alloc,
1001  typename _ExtractKey, typename _Equal,
1002  typename _Hash, typename _RangeHash, typename _Unused,
1003  typename _RehashPolicy, typename _Traits>
1004  struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1005  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
1006  : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1007  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>
1008  {
1009  using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
1010  _Equal, _Hash, _RangeHash, _Unused,
1011  _RehashPolicy, _Traits>;
1012  using value_type = typename __base_type::value_type;
1013  using iterator = typename __base_type::iterator;
1014  using const_iterator = typename __base_type::const_iterator;
1015 
1016  using __unique_keys = typename __base_type::__unique_keys;
1017  using __hashtable = typename __base_type::__hashtable;
1018  using __ireturn_type = typename __base_type::__ireturn_type;
1019 
1020  using __base_type::insert;
1021 
1022  template<typename _Pair>
1024 
1025  template<typename _Pair>
1026  using _IFcons = std::enable_if<__is_cons<_Pair>::value>;
1027 
1028  template<typename _Pair>
1029  using _IFconsp = typename _IFcons<_Pair>::type;
1030 
1031  template<typename _Pair, typename = _IFconsp<_Pair>>
1032  __ireturn_type
1033  insert(_Pair&& __v)
1034  {
1035  __hashtable& __h = this->_M_conjure_hashtable();
1036  return __h._M_emplace(__unique_keys{}, std::forward<_Pair>(__v));
1037  }
1038 
1039  template<typename _Pair, typename = _IFconsp<_Pair>>
1040  iterator
1041  insert(const_iterator __hint, _Pair&& __v)
1042  {
1043  __hashtable& __h = this->_M_conjure_hashtable();
1044  return __h._M_emplace(__hint, __unique_keys{},
1045  std::forward<_Pair>(__v));
1046  }
1047  };
1048 
1049  template<typename _Policy>
1050  using __has_load_factor = typename _Policy::__has_load_factor;
1051 
1052  /**
1053  * Primary class template _Rehash_base.
1054  *
1055  * Give hashtable the max_load_factor functions and reserve iff the
1056  * rehash policy supports it.
1057  */
1058  template<typename _Key, typename _Value, typename _Alloc,
1059  typename _ExtractKey, typename _Equal,
1060  typename _Hash, typename _RangeHash, typename _Unused,
1061  typename _RehashPolicy, typename _Traits,
1062  typename =
1063  __detected_or_t<false_type, __has_load_factor, _RehashPolicy>>
1064  struct _Rehash_base;
1065 
1066  /// Specialization when rehash policy doesn't provide load factor management.
1067  template<typename _Key, typename _Value, typename _Alloc,
1068  typename _ExtractKey, typename _Equal,
1069  typename _Hash, typename _RangeHash, typename _Unused,
1070  typename _RehashPolicy, typename _Traits>
1071  struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1072  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
1073  false_type /* Has load factor */>
1074  {
1075  };
1076 
1077  /// Specialization when rehash policy provide load factor management.
1078  template<typename _Key, typename _Value, typename _Alloc,
1079  typename _ExtractKey, typename _Equal,
1080  typename _Hash, typename _RangeHash, typename _Unused,
1081  typename _RehashPolicy, typename _Traits>
1082  struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1083  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
1084  true_type /* Has load factor */>
1085  {
1086  using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
1087  _Equal, _Hash, _RangeHash, _Unused,
1088  _RehashPolicy, _Traits>;
1089 
1090  float
1091  max_load_factor() const noexcept
1092  {
1093  const __hashtable* __this = static_cast<const __hashtable*>(this);
1094  return __this->__rehash_policy().max_load_factor();
1095  }
1096 
1097  void
1098  max_load_factor(float __z)
1099  {
1100  __hashtable* __this = static_cast<__hashtable*>(this);
1101  __this->__rehash_policy(_RehashPolicy(__z));
1102  }
1103 
1104  void
1105  reserve(std::size_t __n)
1106  {
1107  __hashtable* __this = static_cast<__hashtable*>(this);
1108  __this->rehash(__this->__rehash_policy()._M_bkt_for_elements(__n));
1109  }
1110  };
1111 
1112  /**
1113  * Primary class template _Hashtable_ebo_helper.
1114  *
1115  * Helper class using EBO when it is not forbidden (the type is not
1116  * final) and when it is worth it (the type is empty.)
1117  */
1118  template<int _Nm, typename _Tp,
1119  bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
1120  struct _Hashtable_ebo_helper;
1121 
1122  /// Specialization using EBO.
1123  template<int _Nm, typename _Tp>
1124  struct _Hashtable_ebo_helper<_Nm, _Tp, true>
1125  : private _Tp
1126  {
1127  _Hashtable_ebo_helper() noexcept(noexcept(_Tp())) : _Tp() { }
1128 
1129  template<typename _OtherTp>
1130  _Hashtable_ebo_helper(_OtherTp&& __tp)
1131  : _Tp(std::forward<_OtherTp>(__tp))
1132  { }
1133 
1134  const _Tp& _M_cget() const { return static_cast<const _Tp&>(*this); }
1135  _Tp& _M_get() { return static_cast<_Tp&>(*this); }
1136  };
1137 
1138  /// Specialization not using EBO.
1139  template<int _Nm, typename _Tp>
1140  struct _Hashtable_ebo_helper<_Nm, _Tp, false>
1141  {
1142  _Hashtable_ebo_helper() = default;
1143 
1144  template<typename _OtherTp>
1145  _Hashtable_ebo_helper(_OtherTp&& __tp)
1146  : _M_tp(std::forward<_OtherTp>(__tp))
1147  { }
1148 
1149  const _Tp& _M_cget() const { return _M_tp; }
1150  _Tp& _M_get() { return _M_tp; }
1151 
1152  private:
1153  _Tp _M_tp{};
1154  };
1155 
1156  /**
1157  * Primary class template _Local_iterator_base.
1158  *
1159  * Base class for local iterators, used to iterate within a bucket
1160  * but not between buckets.
1161  */
1162  template<typename _Key, typename _Value, typename _ExtractKey,
1163  typename _Hash, typename _RangeHash, typename _Unused,
1164  bool __cache_hash_code>
1165  struct _Local_iterator_base;
1166 
1167  /**
1168  * Primary class template _Hash_code_base.
1169  *
1170  * Encapsulates two policy issues that aren't quite orthogonal.
1171  * (1) the difference between using a ranged hash function and using
1172  * the combination of a hash function and a range-hashing function.
1173  * In the former case we don't have such things as hash codes, so
1174  * we have a dummy type as placeholder.
1175  * (2) Whether or not we cache hash codes. Caching hash codes is
1176  * meaningless if we have a ranged hash function.
1177  *
1178  * We also put the key extraction objects here, for convenience.
1179  * Each specialization derives from one or more of the template
1180  * parameters to benefit from Ebo. This is important as this type
1181  * is inherited in some cases by the _Local_iterator_base type used
1182  * to implement local_iterator and const_local_iterator. As with
1183  * any iterator type we prefer to make it as small as possible.
1184  */
1185  template<typename _Key, typename _Value, typename _ExtractKey,
1186  typename _Hash, typename _RangeHash, typename _Unused,
1187  bool __cache_hash_code>
1188  struct _Hash_code_base
1189  : private _Hashtable_ebo_helper<1, _Hash>
1190  {
1191  private:
1192  using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>;
1193 
1194  // Gives the local iterator implementation access to _M_bucket_index().
1195  friend struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1196  _Hash, _RangeHash, _Unused, false>;
1197 
1198  public:
1199  typedef _Hash hasher;
1200 
1201  hasher
1202  hash_function() const
1203  { return _M_hash(); }
1204 
1205  protected:
1206  typedef std::size_t __hash_code;
1207 
1208  // We need the default constructor for the local iterators and _Hashtable
1209  // default constructor.
1210  _Hash_code_base() = default;
1211 
1212  _Hash_code_base(const _Hash& __hash) : __ebo_hash(__hash) { }
1213 
1214  __hash_code
1215  _M_hash_code(const _Key& __k) const
1216  {
1217  static_assert(__is_invocable<const _Hash&, const _Key&>{},
1218  "hash function must be invocable with an argument of key type");
1219  return _M_hash()(__k);
1220  }
1221 
1222  template<typename _Kt>
1223  __hash_code
1224  _M_hash_code_tr(const _Kt& __k) const
1225  {
1226  static_assert(__is_invocable<const _Hash&, const _Kt&>{},
1227  "hash function must be invocable with an argument of key type");
1228  return _M_hash()(__k);
1229  }
1230 
1231  std::size_t
1232  _M_bucket_index(__hash_code __c, std::size_t __bkt_count) const
1233  { return _RangeHash{}(__c, __bkt_count); }
1234 
1235  std::size_t
1236  _M_bucket_index(const _Hash_node_value<_Value, false>& __n,
1237  std::size_t __bkt_count) const
1238  noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>()))
1239  && noexcept(declval<const _RangeHash&>()((__hash_code)0,
1240  (std::size_t)0)) )
1241  {
1242  return _RangeHash{}(_M_hash_code(_ExtractKey{}(__n._M_v())),
1243  __bkt_count);
1244  }
1245 
1246  std::size_t
1247  _M_bucket_index(const _Hash_node_value<_Value, true>& __n,
1248  std::size_t __bkt_count) const
1249  noexcept( noexcept(declval<const _RangeHash&>()((__hash_code)0,
1250  (std::size_t)0)) )
1251  { return _RangeHash{}(__n._M_hash_code, __bkt_count); }
1252 
1253  void
1254  _M_store_code(_Hash_node_code_cache<false>&, __hash_code) const
1255  { }
1256 
1257  void
1258  _M_copy_code(_Hash_node_code_cache<false>&,
1259  const _Hash_node_code_cache<false>&) const
1260  { }
1261 
1262  void
1263  _M_store_code(_Hash_node_code_cache<true>& __n, __hash_code __c) const
1264  { __n._M_hash_code = __c; }
1265 
1266  void
1267  _M_copy_code(_Hash_node_code_cache<true>& __to,
1268  const _Hash_node_code_cache<true>& __from) const
1269  { __to._M_hash_code = __from._M_hash_code; }
1270 
1271  void
1272  _M_swap(_Hash_code_base& __x)
1273  { std::swap(__ebo_hash::_M_get(), __x.__ebo_hash::_M_get()); }
1274 
1275  const _Hash&
1276  _M_hash() const { return __ebo_hash::_M_cget(); }
1277  };
1278 
1279  /// Partial specialization used when nodes contain a cached hash code.
1280  template<typename _Key, typename _Value, typename _ExtractKey,
1281  typename _Hash, typename _RangeHash, typename _Unused>
1282  struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1283  _Hash, _RangeHash, _Unused, true>
1284  : public _Node_iterator_base<_Value, true>
1285  {
1286  protected:
1287  using __base_node_iter = _Node_iterator_base<_Value, true>;
1288  using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1289  _Hash, _RangeHash, _Unused, true>;
1290 
1291  _Local_iterator_base() = default;
1292  _Local_iterator_base(const __hash_code_base&,
1293  _Hash_node<_Value, true>* __p,
1294  std::size_t __bkt, std::size_t __bkt_count)
1295  : __base_node_iter(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1296  { }
1297 
1298  void
1299  _M_incr()
1300  {
1301  __base_node_iter::_M_incr();
1302  if (this->_M_cur)
1303  {
1304  std::size_t __bkt
1305  = _RangeHash{}(this->_M_cur->_M_hash_code, _M_bucket_count);
1306  if (__bkt != _M_bucket)
1307  this->_M_cur = nullptr;
1308  }
1309  }
1310 
1311  std::size_t _M_bucket;
1312  std::size_t _M_bucket_count;
1313 
1314  public:
1315  std::size_t
1316  _M_get_bucket() const { return _M_bucket; } // for debug mode
1317  };
1318 
1319  // Uninitialized storage for a _Hash_code_base.
1320  // This type is DefaultConstructible and Assignable even if the
1321  // _Hash_code_base type isn't, so that _Local_iterator_base<..., false>
1322  // can be DefaultConstructible and Assignable.
1323  template<typename _Tp, bool _IsEmpty = std::is_empty<_Tp>::value>
1324  struct _Hash_code_storage
1325  {
1326  __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
1327 
1328  _Tp*
1329  _M_h() { return _M_storage._M_ptr(); }
1330 
1331  const _Tp*
1332  _M_h() const { return _M_storage._M_ptr(); }
1333  };
1334 
1335  // Empty partial specialization for empty _Hash_code_base types.
1336  template<typename _Tp>
1337  struct _Hash_code_storage<_Tp, true>
1338  {
1339  static_assert( std::is_empty<_Tp>::value, "Type must be empty" );
1340 
1341  // As _Tp is an empty type there will be no bytes written/read through
1342  // the cast pointer, so no strict-aliasing violation.
1343  _Tp*
1344  _M_h() { return reinterpret_cast<_Tp*>(this); }
1345 
1346  const _Tp*
1347  _M_h() const { return reinterpret_cast<const _Tp*>(this); }
1348  };
1349 
1350  template<typename _Key, typename _Value, typename _ExtractKey,
1351  typename _Hash, typename _RangeHash, typename _Unused>
1352  using __hash_code_for_local_iter
1353  = _Hash_code_storage<_Hash_code_base<_Key, _Value, _ExtractKey,
1354  _Hash, _RangeHash, _Unused, false>>;
1355 
1356  // Partial specialization used when hash codes are not cached
1357  template<typename _Key, typename _Value, typename _ExtractKey,
1358  typename _Hash, typename _RangeHash, typename _Unused>
1359  struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1360  _Hash, _RangeHash, _Unused, false>
1361  : __hash_code_for_local_iter<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1362  _Unused>
1363  , _Node_iterator_base<_Value, false>
1364  {
1365  protected:
1366  using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1367  _Hash, _RangeHash, _Unused, false>;
1368  using __node_iter_base = _Node_iterator_base<_Value, false>;
1369 
1370  _Local_iterator_base() : _M_bucket_count(-1) { }
1371 
1372  _Local_iterator_base(const __hash_code_base& __base,
1373  _Hash_node<_Value, false>* __p,
1374  std::size_t __bkt, std::size_t __bkt_count)
1375  : __node_iter_base(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1376  { _M_init(__base); }
1377 
1378  ~_Local_iterator_base()
1379  {
1380  if (_M_bucket_count != size_t(-1))
1381  _M_destroy();
1382  }
1383 
1384  _Local_iterator_base(const _Local_iterator_base& __iter)
1385  : __node_iter_base(__iter._M_cur), _M_bucket(__iter._M_bucket)
1386  , _M_bucket_count(__iter._M_bucket_count)
1387  {
1388  if (_M_bucket_count != size_t(-1))
1389  _M_init(*__iter._M_h());
1390  }
1391 
1392  _Local_iterator_base&
1393  operator=(const _Local_iterator_base& __iter)
1394  {
1395  if (_M_bucket_count != -1)
1396  _M_destroy();
1397  this->_M_cur = __iter._M_cur;
1398  _M_bucket = __iter._M_bucket;
1399  _M_bucket_count = __iter._M_bucket_count;
1400  if (_M_bucket_count != -1)
1401  _M_init(*__iter._M_h());
1402  return *this;
1403  }
1404 
1405  void
1406  _M_incr()
1407  {
1408  __node_iter_base::_M_incr();
1409  if (this->_M_cur)
1410  {
1411  std::size_t __bkt = this->_M_h()->_M_bucket_index(*this->_M_cur,
1412  _M_bucket_count);
1413  if (__bkt != _M_bucket)
1414  this->_M_cur = nullptr;
1415  }
1416  }
1417 
1418  std::size_t _M_bucket;
1419  std::size_t _M_bucket_count;
1420 
1421  void
1422  _M_init(const __hash_code_base& __base)
1423  { ::new(this->_M_h()) __hash_code_base(__base); }
1424 
1425  void
1426  _M_destroy() { this->_M_h()->~__hash_code_base(); }
1427 
1428  public:
1429  std::size_t
1430  _M_get_bucket() const { return _M_bucket; } // for debug mode
1431  };
1432 
1433  /// local iterators
1434  template<typename _Key, typename _Value, typename _ExtractKey,
1435  typename _Hash, typename _RangeHash, typename _Unused,
1436  bool __constant_iterators, bool __cache>
1437  struct _Local_iterator
1438  : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1439  _Hash, _RangeHash, _Unused, __cache>
1440  {
1441  private:
1442  using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1443  _Hash, _RangeHash, _Unused, __cache>;
1444  using __hash_code_base = typename __base_type::__hash_code_base;
1445 
1446  public:
1447  typedef _Value value_type;
1448  typedef typename std::conditional<__constant_iterators,
1449  const value_type*, value_type*>::type
1450  pointer;
1451  typedef typename std::conditional<__constant_iterators,
1452  const value_type&, value_type&>::type
1453  reference;
1454  typedef std::ptrdiff_t difference_type;
1455  typedef std::forward_iterator_tag iterator_category;
1456 
1457  _Local_iterator() = default;
1458 
1459  _Local_iterator(const __hash_code_base& __base,
1460  _Hash_node<_Value, __cache>* __n,
1461  std::size_t __bkt, std::size_t __bkt_count)
1462  : __base_type(__base, __n, __bkt, __bkt_count)
1463  { }
1464 
1465  reference
1466  operator*() const
1467  { return this->_M_cur->_M_v(); }
1468 
1469  pointer
1470  operator->() const
1471  { return this->_M_cur->_M_valptr(); }
1472 
1473  _Local_iterator&
1474  operator++()
1475  {
1476  this->_M_incr();
1477  return *this;
1478  }
1479 
1480  _Local_iterator
1481  operator++(int)
1482  {
1483  _Local_iterator __tmp(*this);
1484  this->_M_incr();
1485  return __tmp;
1486  }
1487  };
1488 
1489  /// local const_iterators
1490  template<typename _Key, typename _Value, typename _ExtractKey,
1491  typename _Hash, typename _RangeHash, typename _Unused,
1492  bool __constant_iterators, bool __cache>
1493  struct _Local_const_iterator
1494  : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1495  _Hash, _RangeHash, _Unused, __cache>
1496  {
1497  private:
1498  using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1499  _Hash, _RangeHash, _Unused, __cache>;
1500  using __hash_code_base = typename __base_type::__hash_code_base;
1501 
1502  public:
1503  typedef _Value value_type;
1504  typedef const value_type* pointer;
1505  typedef const value_type& reference;
1506  typedef std::ptrdiff_t difference_type;
1507  typedef std::forward_iterator_tag iterator_category;
1508 
1509  _Local_const_iterator() = default;
1510 
1511  _Local_const_iterator(const __hash_code_base& __base,
1512  _Hash_node<_Value, __cache>* __n,
1513  std::size_t __bkt, std::size_t __bkt_count)
1514  : __base_type(__base, __n, __bkt, __bkt_count)
1515  { }
1516 
1517  _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
1518  _Hash, _RangeHash, _Unused,
1519  __constant_iterators,
1520  __cache>& __x)
1521  : __base_type(__x)
1522  { }
1523 
1524  reference
1525  operator*() const
1526  { return this->_M_cur->_M_v(); }
1527 
1528  pointer
1529  operator->() const
1530  { return this->_M_cur->_M_valptr(); }
1531 
1532  _Local_const_iterator&
1533  operator++()
1534  {
1535  this->_M_incr();
1536  return *this;
1537  }
1538 
1539  _Local_const_iterator
1540  operator++(int)
1541  {
1542  _Local_const_iterator __tmp(*this);
1543  this->_M_incr();
1544  return __tmp;
1545  }
1546  };
1547 
1548  /**
1549  * Primary class template _Hashtable_base.
1550  *
1551  * Helper class adding management of _Equal functor to
1552  * _Hash_code_base type.
1553  *
1554  * Base class templates are:
1555  * - __detail::_Hash_code_base
1556  * - __detail::_Hashtable_ebo_helper
1557  */
1558  template<typename _Key, typename _Value, typename _ExtractKey,
1559  typename _Equal, typename _Hash, typename _RangeHash,
1560  typename _Unused, typename _Traits>
1561  struct _Hashtable_base
1562  : public _Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1563  _Unused, _Traits::__hash_cached::value>,
1564  private _Hashtable_ebo_helper<0, _Equal>
1565  {
1566  public:
1567  typedef _Key key_type;
1568  typedef _Value value_type;
1569  typedef _Equal key_equal;
1570  typedef std::size_t size_type;
1571  typedef std::ptrdiff_t difference_type;
1572 
1573  using __traits_type = _Traits;
1574  using __hash_cached = typename __traits_type::__hash_cached;
1575 
1576  using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1577  _Hash, _RangeHash, _Unused,
1578  __hash_cached::value>;
1579 
1580  using __hash_code = typename __hash_code_base::__hash_code;
1581 
1582  private:
1583  using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>;
1584 
1585  static bool
1586  _S_equals(__hash_code, const _Hash_node_code_cache<false>&)
1587  { return true; }
1588 
1589  static bool
1590  _S_node_equals(const _Hash_node_code_cache<false>&,
1591  const _Hash_node_code_cache<false>&)
1592  { return true; }
1593 
1594  static bool
1595  _S_equals(__hash_code __c, const _Hash_node_code_cache<true>& __n)
1596  { return __c == __n._M_hash_code; }
1597 
1598  static bool
1599  _S_node_equals(const _Hash_node_code_cache<true>& __lhn,
1600  const _Hash_node_code_cache<true>& __rhn)
1601  { return __lhn._M_hash_code == __rhn._M_hash_code; }
1602 
1603  protected:
1604  _Hashtable_base() = default;
1605 
1606  _Hashtable_base(const _Hash& __hash, const _Equal& __eq)
1607  : __hash_code_base(__hash), _EqualEBO(__eq)
1608  { }
1609 
1610  bool
1611  _M_equals(const _Key& __k, __hash_code __c,
1612  const _Hash_node_value<_Value, __hash_cached::value>& __n) const
1613  {
1614  static_assert(__is_invocable<const _Equal&, const _Key&, const _Key&>{},
1615  "key equality predicate must be invocable with two arguments of "
1616  "key type");
1617  return _S_equals(__c, __n) && _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1618  }
1619 
1620  template<typename _Kt>
1621  bool
1622  _M_equals_tr(const _Kt& __k, __hash_code __c,
1623  const _Hash_node_value<_Value,
1624  __hash_cached::value>& __n) const
1625  {
1626  static_assert(
1627  __is_invocable<const _Equal&, const _Kt&, const _Key&>{},
1628  "key equality predicate must be invocable with two arguments of "
1629  "key type");
1630  return _S_equals(__c, __n) && _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1631  }
1632 
1633  bool
1634  _M_node_equals(
1635  const _Hash_node_value<_Value, __hash_cached::value>& __lhn,
1636  const _Hash_node_value<_Value, __hash_cached::value>& __rhn) const
1637  {
1638  return _S_node_equals(__lhn, __rhn)
1639  && _M_eq()(_ExtractKey{}(__lhn._M_v()), _ExtractKey{}(__rhn._M_v()));
1640  }
1641 
1642  void
1643  _M_swap(_Hashtable_base& __x)
1644  {
1645  __hash_code_base::_M_swap(__x);
1646  std::swap(_EqualEBO::_M_get(), __x._EqualEBO::_M_get());
1647  }
1648 
1649  const _Equal&
1650  _M_eq() const { return _EqualEBO::_M_cget(); }
1651  };
1652 
1653  /**
1654  * Primary class template _Equality.
1655  *
1656  * This is for implementing equality comparison for unordered
1657  * containers, per N3068, by John Lakos and Pablo Halpern.
1658  * Algorithmically, we follow closely the reference implementations
1659  * therein.
1660  */
1661  template<typename _Key, typename _Value, typename _Alloc,
1662  typename _ExtractKey, typename _Equal,
1663  typename _Hash, typename _RangeHash, typename _Unused,
1664  typename _RehashPolicy, typename _Traits,
1665  bool _Unique_keys = _Traits::__unique_keys::value>
1666  struct _Equality;
1667 
1668  /// unordered_map and unordered_set specializations.
1669  template<typename _Key, typename _Value, typename _Alloc,
1670  typename _ExtractKey, typename _Equal,
1671  typename _Hash, typename _RangeHash, typename _Unused,
1672  typename _RehashPolicy, typename _Traits>
1673  struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1674  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
1675  {
1676  using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1677  _Hash, _RangeHash, _Unused,
1678  _RehashPolicy, _Traits>;
1679 
1680  bool
1681  _M_equal(const __hashtable&) const;
1682  };
1683 
1684  template<typename _Key, typename _Value, typename _Alloc,
1685  typename _ExtractKey, typename _Equal,
1686  typename _Hash, typename _RangeHash, typename _Unused,
1687  typename _RehashPolicy, typename _Traits>
1688  bool
1689  _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1690  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
1691  _M_equal(const __hashtable& __other) const
1692  {
1693  using __node_type = typename __hashtable::__node_type;
1694  const __hashtable* __this = static_cast<const __hashtable*>(this);
1695  if (__this->size() != __other.size())
1696  return false;
1697 
1698  for (auto __itx = __this->begin(); __itx != __this->end(); ++__itx)
1699  {
1700  std::size_t __ybkt = __other._M_bucket_index(*__itx._M_cur);
1701  auto __prev_n = __other._M_buckets[__ybkt];
1702  if (!__prev_n)
1703  return false;
1704 
1705  for (__node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);;
1706  __n = __n->_M_next())
1707  {
1708  if (__n->_M_v() == *__itx)
1709  break;
1710 
1711  if (!__n->_M_nxt
1712  || __other._M_bucket_index(*__n->_M_next()) != __ybkt)
1713  return false;
1714  }
1715  }
1716 
1717  return true;
1718  }
1719 
1720  /// unordered_multiset and unordered_multimap specializations.
1721  template<typename _Key, typename _Value, typename _Alloc,
1722  typename _ExtractKey, typename _Equal,
1723  typename _Hash, typename _RangeHash, typename _Unused,
1724  typename _RehashPolicy, typename _Traits>
1725  struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1726  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
1727  {
1728  using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1729  _Hash, _RangeHash, _Unused,
1730  _RehashPolicy, _Traits>;
1731 
1732  bool
1733  _M_equal(const __hashtable&) const;
1734  };
1735 
1736  template<typename _Key, typename _Value, typename _Alloc,
1737  typename _ExtractKey, typename _Equal,
1738  typename _Hash, typename _RangeHash, typename _Unused,
1739  typename _RehashPolicy, typename _Traits>
1740  bool
1741  _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1742  _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>::
1743  _M_equal(const __hashtable& __other) const
1744  {
1745  using __node_type = typename __hashtable::__node_type;
1746  const __hashtable* __this = static_cast<const __hashtable*>(this);
1747  if (__this->size() != __other.size())
1748  return false;
1749 
1750  for (auto __itx = __this->begin(); __itx != __this->end();)
1751  {
1752  std::size_t __x_count = 1;
1753  auto __itx_end = __itx;
1754  for (++__itx_end; __itx_end != __this->end()
1755  && __this->key_eq()(_ExtractKey{}(*__itx),
1756  _ExtractKey{}(*__itx_end));
1757  ++__itx_end)
1758  ++__x_count;
1759 
1760  std::size_t __ybkt = __other._M_bucket_index(*__itx._M_cur);
1761  auto __y_prev_n = __other._M_buckets[__ybkt];
1762  if (!__y_prev_n)
1763  return false;
1764 
1765  __node_type* __y_n = static_cast<__node_type*>(__y_prev_n->_M_nxt);
1766  for (;;)
1767  {
1768  if (__this->key_eq()(_ExtractKey{}(__y_n->_M_v()),
1769  _ExtractKey{}(*__itx)))
1770  break;
1771 
1772  auto __y_ref_n = __y_n;
1773  for (__y_n = __y_n->_M_next(); __y_n; __y_n = __y_n->_M_next())
1774  if (!__other._M_node_equals(*__y_ref_n, *__y_n))
1775  break;
1776 
1777  if (!__y_n || __other._M_bucket_index(*__y_n) != __ybkt)
1778  return false;
1779  }
1780 
1781  typename __hashtable::const_iterator __ity(__y_n);
1782  for (auto __ity_end = __ity; __ity_end != __other.end(); ++__ity_end)
1783  if (--__x_count == 0)
1784  break;
1785 
1786  if (__x_count != 0)
1787  return false;
1788 
1789  if (!std::is_permutation(__itx, __itx_end, __ity))
1790  return false;
1791 
1792  __itx = __itx_end;
1793  }
1794  return true;
1795  }
1796 
1797  /**
1798  * This type deals with all allocation and keeps an allocator instance
1799  * through inheritance to benefit from EBO when possible.
1800  */
1801  template<typename _NodeAlloc>
1802  struct _Hashtable_alloc : private _Hashtable_ebo_helper<0, _NodeAlloc>
1803  {
1804  private:
1805  using __ebo_node_alloc = _Hashtable_ebo_helper<0, _NodeAlloc>;
1806  public:
1807  using __node_type = typename _NodeAlloc::value_type;
1808  using __node_alloc_type = _NodeAlloc;
1809  // Use __gnu_cxx to benefit from _S_always_equal and al.
1810  using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
1811 
1812  using __value_alloc_traits = typename __node_alloc_traits::template
1813  rebind_traits<typename __node_type::value_type>;
1814 
1815  using __node_ptr = __node_type*;
1816  using __node_base = _Hash_node_base;
1817  using __node_base_ptr = __node_base*;
1818  using __buckets_alloc_type =
1819  __alloc_rebind<__node_alloc_type, __node_base_ptr>;
1820  using __buckets_alloc_traits = std::allocator_traits<__buckets_alloc_type>;
1821  using __buckets_ptr = __node_base_ptr*;
1822 
1823  _Hashtable_alloc() = default;
1824  _Hashtable_alloc(const _Hashtable_alloc&) = default;
1825  _Hashtable_alloc(_Hashtable_alloc&&) = default;
1826 
1827  template<typename _Alloc>
1828  _Hashtable_alloc(_Alloc&& __a)
1829  : __ebo_node_alloc(std::forward<_Alloc>(__a))
1830  { }
1831 
1832  __node_alloc_type&
1833  _M_node_allocator()
1834  { return __ebo_node_alloc::_M_get(); }
1835 
1836  const __node_alloc_type&
1837  _M_node_allocator() const
1838  { return __ebo_node_alloc::_M_cget(); }
1839 
1840  // Allocate a node and construct an element within it.
1841  template<typename... _Args>
1842  __node_ptr
1843  _M_allocate_node(_Args&&... __args);
1844 
1845  // Destroy the element within a node and deallocate the node.
1846  void
1847  _M_deallocate_node(__node_ptr __n);
1848 
1849  // Deallocate a node.
1850  void
1851  _M_deallocate_node_ptr(__node_ptr __n);
1852 
1853  // Deallocate the linked list of nodes pointed to by __n.
1854  // The elements within the nodes are destroyed.
1855  void
1856  _M_deallocate_nodes(__node_ptr __n);
1857 
1858  __buckets_ptr
1859  _M_allocate_buckets(std::size_t __bkt_count);
1860 
1861  void
1862  _M_deallocate_buckets(__buckets_ptr, std::size_t __bkt_count);
1863  };
1864 
1865  // Definitions of class template _Hashtable_alloc's out-of-line member
1866  // functions.
1867  template<typename _NodeAlloc>
1868  template<typename... _Args>
1869  auto
1870  _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
1871  -> __node_ptr
1872  {
1873  auto __nptr = __node_alloc_traits::allocate(_M_node_allocator(), 1);
1874  __node_ptr __n = std::__to_address(__nptr);
1875  __try
1876  {
1877  ::new ((void*)__n) __node_type;
1878  __node_alloc_traits::construct(_M_node_allocator(),
1879  __n->_M_valptr(),
1880  std::forward<_Args>(__args)...);
1881  return __n;
1882  }
1883  __catch(...)
1884  {
1885  __node_alloc_traits::deallocate(_M_node_allocator(), __nptr, 1);
1886  __throw_exception_again;
1887  }
1888  }
1889 
1890  template<typename _NodeAlloc>
1891  void
1892  _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_ptr __n)
1893  {
1894  __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
1895  _M_deallocate_node_ptr(__n);
1896  }
1897 
1898  template<typename _NodeAlloc>
1899  void
1900  _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node_ptr(__node_ptr __n)
1901  {
1902  typedef typename __node_alloc_traits::pointer _Ptr;
1903  auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
1904  __n->~__node_type();
1905  __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
1906  }
1907 
1908  template<typename _NodeAlloc>
1909  void
1910  _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_ptr __n)
1911  {
1912  while (__n)
1913  {
1914  __node_ptr __tmp = __n;
1915  __n = __n->_M_next();
1916  _M_deallocate_node(__tmp);
1917  }
1918  }
1919 
1920  template<typename _NodeAlloc>
1921  auto
1922  _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(std::size_t __bkt_count)
1923  -> __buckets_ptr
1924  {
1925  __buckets_alloc_type __alloc(_M_node_allocator());
1926 
1927  auto __ptr = __buckets_alloc_traits::allocate(__alloc, __bkt_count);
1928  __buckets_ptr __p = std::__to_address(__ptr);
1929  __builtin_memset(__p, 0, __bkt_count * sizeof(__node_base_ptr));
1930  return __p;
1931  }
1932 
1933  template<typename _NodeAlloc>
1934  void
1935  _Hashtable_alloc<_NodeAlloc>::
1936  _M_deallocate_buckets(__buckets_ptr __bkts,
1937  std::size_t __bkt_count)
1938  {
1939  typedef typename __buckets_alloc_traits::pointer _Ptr;
1940  auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
1941  __buckets_alloc_type __alloc(_M_node_allocator());
1942  __buckets_alloc_traits::deallocate(__alloc, __ptr, __bkt_count);
1943  }
1944 
1945  ///@} hashtable-detail
1946 } // namespace __detail
1947 /// @endcond
1948 _GLIBCXX_END_NAMESPACE_VERSION
1949 } // namespace std
1950 
1951 #endif // _HASHTABLE_POLICY_H
constexpr complex< _Tp > operator*(const complex< _Tp > &__x, const complex< _Tp > &__y)
Return new complex value x times y.
Definition: complex:392
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition: type_traits:83
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
Definition: type_traits:86
constexpr piecewise_construct_t piecewise_construct
Tag for piecewise construction of std::pair objects.
Definition: stl_pair.h:83
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
constexpr tuple< _Elements &&... > forward_as_tuple(_Elements &&... __args) noexcept
std::forward_as_tuple
Definition: tuple:1617
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition: move.h:77
void swap(any &__x, any &__y) noexcept
Exchange the states of two any objects.
Definition: any:428
constexpr iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
ISO C++ entities toplevel namespace is std.
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
__numeric_traits_integer< _Tp > __int_traits
Convenience alias for __numeric_traits<integer-type>.
constexpr _Iterator __base(_Iterator __it)
tuple_element
Definition: array:442
Primary class template, tuple.
Definition: tuple:610
Define a member typedef type to one of two argument types.
Definition: type_traits:2227
is_empty
Definition: type_traits:757
is_constructible
Definition: type_traits:954
Define a member typedef type only if a boolean constant is true.
Definition: type_traits:2200
Uniform interface to all allocator types.
Traits class for iterators.
Uniform interface to all pointer-like types.
Definition: ptr_traits.h:101
Marking input iterators.
Forward iterators support a superset of input iterator operations.
Struct holding two objects of arbitrary type.
Definition: stl_pair.h:213
Uniform interface to C++98 and C++11 allocators.