1 // Internal policy header for unordered_set and unordered_map -*- C++ -*-
2
3 // Copyright (C) 2010, 2011, 2012 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
_GLIBCXX_VISIBILITY(default)34 namespace std _GLIBCXX_VISIBILITY(default)
35 {
36 namespace __detail
37 {
38 _GLIBCXX_BEGIN_NAMESPACE_VERSION
39
40 // Helper function: return distance(first, last) for forward
41 // iterators, or 0 for input iterators.
42 template<class _Iterator>
43 inline typename std::iterator_traits<_Iterator>::difference_type
44 __distance_fw(_Iterator __first, _Iterator __last,
45 std::input_iterator_tag)
46 { return 0; }
47
48 template<class _Iterator>
49 inline typename std::iterator_traits<_Iterator>::difference_type
50 __distance_fw(_Iterator __first, _Iterator __last,
51 std::forward_iterator_tag)
52 { return std::distance(__first, __last); }
53
54 template<class _Iterator>
55 inline typename std::iterator_traits<_Iterator>::difference_type
56 __distance_fw(_Iterator __first, _Iterator __last)
57 {
58 typedef typename std::iterator_traits<_Iterator>::iterator_category _Tag;
59 return __distance_fw(__first, __last, _Tag());
60 }
61
62 // Helper type used to detect whether the hash functor is noexcept.
63 template <typename _Key, typename _Hash>
64 struct __is_noexcept_hash : std::integral_constant<bool,
65 noexcept(declval<const _Hash&>()(declval<const _Key&>()))>
66 {};
67
68 // Auxiliary types used for all instantiations of _Hashtable: nodes
69 // and iterators.
70
71 // Nodes, used to wrap elements stored in the hash table. A policy
72 // template parameter of class template _Hashtable controls whether
73 // nodes also store a hash code. In some cases (e.g. strings) this
74 // may be a performance win.
75 struct _Hash_node_base
76 {
77 _Hash_node_base* _M_nxt;
78
79 _Hash_node_base()
80 : _M_nxt() { }
81 _Hash_node_base(_Hash_node_base* __next)
82 : _M_nxt(__next) { }
83 };
84
85 template<typename _Value, bool __cache_hash_code>
86 struct _Hash_node;
87
88 template<typename _Value>
89 struct _Hash_node<_Value, true> : _Hash_node_base
90 {
91 _Value _M_v;
92 std::size_t _M_hash_code;
93
94 template<typename... _Args>
95 _Hash_node(_Args&&... __args)
96 : _M_v(std::forward<_Args>(__args)...), _M_hash_code() { }
97
98 _Hash_node* _M_next() const
99 { return static_cast<_Hash_node*>(_M_nxt); }
100 };
101
102 template<typename _Value>
103 struct _Hash_node<_Value, false> : _Hash_node_base
104 {
105 _Value _M_v;
106
107 template<typename... _Args>
108 _Hash_node(_Args&&... __args)
109 : _M_v(std::forward<_Args>(__args)...) { }
110
111 _Hash_node* _M_next() const
112 { return static_cast<_Hash_node*>(_M_nxt); }
113 };
114
115 // Node iterators, used to iterate through all the hashtable.
116 template<typename _Value, bool __cache>
117 struct _Node_iterator_base
118 {
119 _Node_iterator_base(_Hash_node<_Value, __cache>* __p)
120 : _M_cur(__p) { }
121
122 void
123 _M_incr()
124 { _M_cur = _M_cur->_M_next(); }
125
126 _Hash_node<_Value, __cache>* _M_cur;
127 };
128
129 template<typename _Value, bool __cache>
130 inline bool
131 operator==(const _Node_iterator_base<_Value, __cache>& __x,
132 const _Node_iterator_base<_Value, __cache>& __y)
133 { return __x._M_cur == __y._M_cur; }
134
135 template<typename _Value, bool __cache>
136 inline bool
137 operator!=(const _Node_iterator_base<_Value, __cache>& __x,
138 const _Node_iterator_base<_Value, __cache>& __y)
139 { return __x._M_cur != __y._M_cur; }
140
141 template<typename _Value, bool __constant_iterators, bool __cache>
142 struct _Node_iterator
143 : public _Node_iterator_base<_Value, __cache>
144 {
145 typedef _Value value_type;
146 typedef typename std::conditional<__constant_iterators,
147 const _Value*, _Value*>::type
148 pointer;
149 typedef typename std::conditional<__constant_iterators,
150 const _Value&, _Value&>::type
151 reference;
152 typedef std::ptrdiff_t difference_type;
153 typedef std::forward_iterator_tag iterator_category;
154
155 _Node_iterator()
156 : _Node_iterator_base<_Value, __cache>(0) { }
157
158 explicit
159 _Node_iterator(_Hash_node<_Value, __cache>* __p)
160 : _Node_iterator_base<_Value, __cache>(__p) { }
161
162 reference
163 operator*() const
164 { return this->_M_cur->_M_v; }
165
166 pointer
167 operator->() const
168 { return std::__addressof(this->_M_cur->_M_v); }
169
170 _Node_iterator&
171 operator++()
172 {
173 this->_M_incr();
174 return *this;
175 }
176
177 _Node_iterator
178 operator++(int)
179 {
180 _Node_iterator __tmp(*this);
181 this->_M_incr();
182 return __tmp;
183 }
184 };
185
186 template<typename _Value, bool __constant_iterators, bool __cache>
187 struct _Node_const_iterator
188 : public _Node_iterator_base<_Value, __cache>
189 {
190 typedef _Value value_type;
191 typedef const _Value* pointer;
192 typedef const _Value& reference;
193 typedef std::ptrdiff_t difference_type;
194 typedef std::forward_iterator_tag iterator_category;
195
196 _Node_const_iterator()
197 : _Node_iterator_base<_Value, __cache>(0) { }
198
199 explicit
200 _Node_const_iterator(_Hash_node<_Value, __cache>* __p)
201 : _Node_iterator_base<_Value, __cache>(__p) { }
202
203 _Node_const_iterator(const _Node_iterator<_Value, __constant_iterators,
204 __cache>& __x)
205 : _Node_iterator_base<_Value, __cache>(__x._M_cur) { }
206
207 reference
208 operator*() const
209 { return this->_M_cur->_M_v; }
210
211 pointer
212 operator->() const
213 { return std::__addressof(this->_M_cur->_M_v); }
214
215 _Node_const_iterator&
216 operator++()
217 {
218 this->_M_incr();
219 return *this;
220 }
221
222 _Node_const_iterator
223 operator++(int)
224 {
225 _Node_const_iterator __tmp(*this);
226 this->_M_incr();
227 return __tmp;
228 }
229 };
230
231 // Many of class template _Hashtable's template parameters are policy
232 // classes. These are defaults for the policies.
233
234 // Default range hashing function: use division to fold a large number
235 // into the range [0, N).
236 struct _Mod_range_hashing
237 {
238 typedef std::size_t first_argument_type;
239 typedef std::size_t second_argument_type;
240 typedef std::size_t result_type;
241
242 result_type
243 operator()(first_argument_type __num, second_argument_type __den) const
244 { return __num % __den; }
245 };
246
247 // Default ranged hash function H. In principle it should be a
248 // function object composed from objects of type H1 and H2 such that
249 // h(k, N) = h2(h1(k), N), but that would mean making extra copies of
250 // h1 and h2. So instead we'll just use a tag to tell class template
251 // hashtable to do that composition.
252 struct _Default_ranged_hash { };
253
254 // Default value for rehash policy. Bucket size is (usually) the
255 // smallest prime that keeps the load factor small enough.
256 struct _Prime_rehash_policy
257 {
258 _Prime_rehash_policy(float __z = 1.0)
259 : _M_max_load_factor(__z), _M_prev_resize(0), _M_next_resize(0) { }
260
261 float
262 max_load_factor() const noexcept
263 { return _M_max_load_factor; }
264
265 // Return a bucket size no smaller than n.
266 std::size_t
267 _M_next_bkt(std::size_t __n) const;
268
269 // Return a bucket count appropriate for n elements
270 std::size_t
271 _M_bkt_for_elements(std::size_t __n) const;
272
273 // __n_bkt is current bucket count, __n_elt is current element count,
274 // and __n_ins is number of elements to be inserted. Do we need to
275 // increase bucket count? If so, return make_pair(true, n), where n
276 // is the new bucket count. If not, return make_pair(false, 0).
277 std::pair<bool, std::size_t>
278 _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
279 std::size_t __n_ins) const;
280
281 typedef std::pair<std::size_t, std::size_t> _State;
282
283 _State
284 _M_state() const
285 { return std::make_pair(_M_prev_resize, _M_next_resize); }
286
287 void
288 _M_reset(const _State& __state)
289 {
290 _M_prev_resize = __state.first;
291 _M_next_resize = __state.second;
292 }
293
294 enum { _S_n_primes = sizeof(unsigned long) != 8 ? 256 : 256 + 48 };
295
296 static const std::size_t _S_growth_factor = 2;
297
298 float _M_max_load_factor;
299 mutable std::size_t _M_prev_resize;
300 mutable std::size_t _M_next_resize;
301 };
302
303 extern const unsigned long __prime_list[];
304
305 // XXX This is a hack. There's no good reason for any of
306 // _Prime_rehash_policy's member functions to be inline.
307
308 // Return a prime no smaller than n.
309 inline std::size_t
310 _Prime_rehash_policy::
311 _M_next_bkt(std::size_t __n) const
312 {
313 // Optimize lookups involving the first elements of __prime_list.
314 // (useful to speed-up, eg, constructors)
315 static const unsigned char __fast_bkt[12]
316 = { 2, 2, 2, 3, 5, 5, 7, 7, 11, 11, 11, 11 };
317
318 const std::size_t __grown_n = __n * _S_growth_factor;
319 if (__grown_n <= 11)
320 {
321 _M_prev_resize = 0;
322 _M_next_resize
323 = __builtin_ceil(__fast_bkt[__grown_n]
324 * (long double)_M_max_load_factor);
325 return __fast_bkt[__grown_n];
326 }
327
328 const unsigned long* __next_bkt
329 = std::lower_bound(__prime_list + 5, __prime_list + _S_n_primes,
330 __grown_n);
331 const unsigned long* __prev_bkt
332 = std::lower_bound(__prime_list + 1, __next_bkt, __n / _S_growth_factor);
333
334 _M_prev_resize
335 = __builtin_floor(*(__prev_bkt - 1) * (long double)_M_max_load_factor);
336 _M_next_resize
337 = __builtin_ceil(*__next_bkt * (long double)_M_max_load_factor);
338 return *__next_bkt;
339 }
340
341 // Return the smallest prime p such that alpha p >= n, where alpha
342 // is the load factor.
343 inline std::size_t
344 _Prime_rehash_policy::
345 _M_bkt_for_elements(std::size_t __n) const
346 { return _M_next_bkt(__builtin_ceil(__n / (long double)_M_max_load_factor)); }
347
348 // Finds the smallest prime p such that alpha p > __n_elt + __n_ins.
349 // If p > __n_bkt, return make_pair(true, p); otherwise return
350 // make_pair(false, 0). In principle this isn't very different from
351 // _M_bkt_for_elements.
352
353 // The only tricky part is that we're caching the element count at
354 // which we need to rehash, so we don't have to do a floating-point
355 // multiply for every insertion.
356
357 inline std::pair<bool, std::size_t>
358 _Prime_rehash_policy::
359 _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
360 std::size_t __n_ins) const
361 {
362 if (__n_elt + __n_ins >= _M_next_resize)
363 {
364 long double __min_bkts = (__n_elt + __n_ins)
365 / (long double)_M_max_load_factor;
366 if (__min_bkts >= __n_bkt)
367 return std::make_pair(true,
368 _M_next_bkt(__builtin_floor(__min_bkts) + 1));
369 else
370 {
371 _M_next_resize
372 = __builtin_floor(__n_bkt * (long double)_M_max_load_factor);
373 return std::make_pair(false, 0);
374 }
375 }
376 else if (__n_elt + __n_ins < _M_prev_resize)
377 {
378 long double __min_bkts = (__n_elt + __n_ins)
379 / (long double)_M_max_load_factor;
380 return std::make_pair(true,
381 _M_next_bkt(__builtin_floor(__min_bkts) + 1));
382 }
383 else
384 return std::make_pair(false, 0);
385 }
386
387 // Base classes for std::_Hashtable. We define these base classes
388 // because in some cases we want to do different things depending
389 // on the value of a policy class. In some cases the policy class
390 // affects which member functions and nested typedefs are defined;
391 // we handle that by specializing base class templates. Several of
392 // the base class templates need to access other members of class
393 // template _Hashtable, so we use the "curiously recurring template
394 // pattern" for them.
395
396 // class template _Map_base. If the hashtable has a value type of
397 // the form pair<T1, T2> and a key extraction policy that returns the
398 // first part of the pair, the hashtable gets a mapped_type typedef.
399 // If it satisfies those criteria and also has unique keys, then it
400 // also gets an operator[].
401 template<typename _Key, typename _Value, typename _Ex, bool __unique,
402 typename _Hashtable>
403 struct _Map_base { };
404
405 template<typename _Key, typename _Pair, typename _Hashtable>
406 struct _Map_base<_Key, _Pair, std::_Select1st<_Pair>, false, _Hashtable>
407 {
408 typedef typename _Pair::second_type mapped_type;
409 };
410
411 template<typename _Key, typename _Pair, typename _Hashtable>
412 struct _Map_base<_Key, _Pair, std::_Select1st<_Pair>, true, _Hashtable>
413 {
414 typedef typename _Pair::second_type mapped_type;
415
416 mapped_type&
417 operator[](const _Key& __k);
418
419 mapped_type&
420 operator[](_Key&& __k);
421
422 // _GLIBCXX_RESOLVE_LIB_DEFECTS
423 // DR 761. unordered_map needs an at() member function.
424 mapped_type&
425 at(const _Key& __k);
426
427 const mapped_type&
428 at(const _Key& __k) const;
429 };
430
431 template<typename _Key, typename _Pair, typename _Hashtable>
432 typename _Map_base<_Key, _Pair, std::_Select1st<_Pair>,
433 true, _Hashtable>::mapped_type&
434 _Map_base<_Key, _Pair, std::_Select1st<_Pair>, true, _Hashtable>::
435 operator[](const _Key& __k)
436 {
437 _Hashtable* __h = static_cast<_Hashtable*>(this);
438 typename _Hashtable::_Hash_code_type __code = __h->_M_hash_code(__k);
439 std::size_t __n = __h->_M_bucket_index(__k, __code);
440
441 typename _Hashtable::_Node* __p = __h->_M_find_node(__n, __k, __code);
442 if (!__p)
443 return __h->_M_insert_bucket(std::make_pair(__k, mapped_type()),
444 __n, __code)->second;
445 return (__p->_M_v).second;
446 }
447
448 template<typename _Key, typename _Pair, typename _Hashtable>
449 typename _Map_base<_Key, _Pair, std::_Select1st<_Pair>,
450 true, _Hashtable>::mapped_type&
451 _Map_base<_Key, _Pair, std::_Select1st<_Pair>, true, _Hashtable>::
452 operator[](_Key&& __k)
453 {
454 _Hashtable* __h = static_cast<_Hashtable*>(this);
455 typename _Hashtable::_Hash_code_type __code = __h->_M_hash_code(__k);
456 std::size_t __n = __h->_M_bucket_index(__k, __code);
457
458 typename _Hashtable::_Node* __p = __h->_M_find_node(__n, __k, __code);
459 if (!__p)
460 return __h->_M_insert_bucket(std::make_pair(std::move(__k),
461 mapped_type()),
462 __n, __code)->second;
463 return (__p->_M_v).second;
464 }
465
466 template<typename _Key, typename _Pair, typename _Hashtable>
467 typename _Map_base<_Key, _Pair, std::_Select1st<_Pair>,
468 true, _Hashtable>::mapped_type&
469 _Map_base<_Key, _Pair, std::_Select1st<_Pair>, true, _Hashtable>::
470 at(const _Key& __k)
471 {
472 _Hashtable* __h = static_cast<_Hashtable*>(this);
473 typename _Hashtable::_Hash_code_type __code = __h->_M_hash_code(__k);
474 std::size_t __n = __h->_M_bucket_index(__k, __code);
475
476 typename _Hashtable::_Node* __p = __h->_M_find_node(__n, __k, __code);
477 if (!__p)
478 __throw_out_of_range(__N("_Map_base::at"));
479 return (__p->_M_v).second;
480 }
481
482 template<typename _Key, typename _Pair, typename _Hashtable>
483 const typename _Map_base<_Key, _Pair, std::_Select1st<_Pair>,
484 true, _Hashtable>::mapped_type&
485 _Map_base<_Key, _Pair, std::_Select1st<_Pair>, true, _Hashtable>::
486 at(const _Key& __k) const
487 {
488 const _Hashtable* __h = static_cast<const _Hashtable*>(this);
489 typename _Hashtable::_Hash_code_type __code = __h->_M_hash_code(__k);
490 std::size_t __n = __h->_M_bucket_index(__k, __code);
491
492 typename _Hashtable::_Node* __p = __h->_M_find_node(__n, __k, __code);
493 if (!__p)
494 __throw_out_of_range(__N("_Map_base::at"));
495 return (__p->_M_v).second;
496 }
497
498 // class template _Rehash_base. Give hashtable the max_load_factor
499 // functions and reserve iff the rehash policy is _Prime_rehash_policy.
500 template<typename _RehashPolicy, typename _Hashtable>
501 struct _Rehash_base { };
502
503 template<typename _Hashtable>
504 struct _Rehash_base<_Prime_rehash_policy, _Hashtable>
505 {
506 float
507 max_load_factor() const noexcept
508 {
509 const _Hashtable* __this = static_cast<const _Hashtable*>(this);
510 return __this->__rehash_policy().max_load_factor();
511 }
512
513 void
514 max_load_factor(float __z)
515 {
516 _Hashtable* __this = static_cast<_Hashtable*>(this);
517 __this->__rehash_policy(_Prime_rehash_policy(__z));
518 }
519
520 void
521 reserve(std::size_t __n)
522 {
523 _Hashtable* __this = static_cast<_Hashtable*>(this);
524 __this->rehash(__builtin_ceil(__n / max_load_factor()));
525 }
526 };
527
528 // Helper class using EBO when it is not forbidden, type is not final,
529 // and when it worth it, type is empty.
530 template<int _Nm, typename _Tp,
531 bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
532 struct _Hashtable_ebo_helper;
533
534 // Specialization using EBO.
535 template<int _Nm, typename _Tp>
536 struct _Hashtable_ebo_helper<_Nm, _Tp, true>
537 // See PR53067.
538 : public _Tp
539 {
540 _Hashtable_ebo_helper() = default;
541 _Hashtable_ebo_helper(const _Tp& __tp) : _Tp(__tp)
542 { }
543
544 static const _Tp&
545 _S_cget(const _Hashtable_ebo_helper& __eboh)
546 { return static_cast<const _Tp&>(__eboh); }
547
548 static _Tp&
549 _S_get(_Hashtable_ebo_helper& __eboh)
550 { return static_cast<_Tp&>(__eboh); }
551 };
552
553 // Specialization not using EBO.
554 template<int _Nm, typename _Tp>
555 struct _Hashtable_ebo_helper<_Nm, _Tp, false>
556 {
557 _Hashtable_ebo_helper() = default;
558 _Hashtable_ebo_helper(const _Tp& __tp) : _M_tp(__tp)
559 { }
560
561 static const _Tp&
562 _S_cget(const _Hashtable_ebo_helper& __eboh)
563 { return __eboh._M_tp; }
564
565 static _Tp&
566 _S_get(_Hashtable_ebo_helper& __eboh)
567 { return __eboh._M_tp; }
568
569 private:
570 _Tp _M_tp;
571 };
572
573 // Class template _Hash_code_base. Encapsulates two policy issues that
574 // aren't quite orthogonal.
575 // (1) the difference between using a ranged hash function and using
576 // the combination of a hash function and a range-hashing function.
577 // In the former case we don't have such things as hash codes, so
578 // we have a dummy type as placeholder.
579 // (2) Whether or not we cache hash codes. Caching hash codes is
580 // meaningless if we have a ranged hash function.
581 // We also put the key extraction objects here, for convenience.
582 //
583 // Each specialization derives from one or more of the template parameters to
584 // benefit from Ebo. This is important as this type is inherited in some cases
585 // by the _Local_iterator_base type used to implement local_iterator and
586 // const_local_iterator. As with any iterator type we prefer to make it as
587 // small as possible.
588
589 // Primary template: unused except as a hook for specializations.
590 template<typename _Key, typename _Value, typename _ExtractKey,
591 typename _H1, typename _H2, typename _Hash,
592 bool __cache_hash_code>
593 struct _Hash_code_base;
594
595 // Specialization: ranged hash function, no caching hash codes. H1
596 // and H2 are provided but ignored. We define a dummy hash code type.
597 template<typename _Key, typename _Value, typename _ExtractKey,
598 typename _H1, typename _H2, typename _Hash>
599 struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, false>
600 // See PR53067.
601 : public _Hashtable_ebo_helper<0, _ExtractKey>,
602 public _Hashtable_ebo_helper<1, _Hash>
603 {
604 private:
605 typedef _Hashtable_ebo_helper<0, _ExtractKey> _EboExtractKey;
606 typedef _Hashtable_ebo_helper<1, _Hash> _EboHash;
607
608 protected:
609 // We need the default constructor for the local iterators.
610 _Hash_code_base() = default;
611 _Hash_code_base(const _ExtractKey& __ex,
612 const _H1&, const _H2&, const _Hash& __h)
613 : _EboExtractKey(__ex), _EboHash(__h) { }
614
615 typedef void* _Hash_code_type;
616
617 _Hash_code_type
618 _M_hash_code(const _Key& __key) const
619 { return 0; }
620
621 std::size_t
622 _M_bucket_index(const _Key& __k, _Hash_code_type,
623 std::size_t __n) const
624 { return _M_ranged_hash()(__k, __n); }
625
626 std::size_t
627 _M_bucket_index(const _Hash_node<_Value, false>* __p,
628 std::size_t __n) const
629 { return _M_ranged_hash()(_M_extract()(__p->_M_v), __n); }
630
631 void
632 _M_store_code(_Hash_node<_Value, false>*, _Hash_code_type) const
633 { }
634
635 void
636 _M_copy_code(_Hash_node<_Value, false>*,
637 const _Hash_node<_Value, false>*) const
638 { }
639
640 void
641 _M_swap(_Hash_code_base& __x)
642 {
643 std::swap(_M_extract(), __x._M_extract());
644 std::swap(_M_ranged_hash(), __x._M_ranged_hash());
645 }
646
647 protected:
648 const _ExtractKey&
649 _M_extract() const { return _EboExtractKey::_S_cget(*this); }
650 _ExtractKey&
651 _M_extract() { return _EboExtractKey::_S_get(*this); }
652 const _Hash&
653 _M_ranged_hash() const { return _EboHash::_S_cget(*this); }
654 _Hash&
655 _M_ranged_hash() { return _EboHash::_S_get(*this); }
656 };
657
658 // No specialization for ranged hash function while caching hash codes.
659 // That combination is meaningless, and trying to do it is an error.
660
661 // Specialization: ranged hash function, cache hash codes. This
662 // combination is meaningless, so we provide only a declaration
663 // and no definition.
664 template<typename _Key, typename _Value, typename _ExtractKey,
665 typename _H1, typename _H2, typename _Hash>
666 struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash, true>;
667
668 // Specialization: hash function and range-hashing function, no
669 // caching of hash codes.
670 // Provides typedef and accessor required by TR1.
671 template<typename _Key, typename _Value, typename _ExtractKey,
672 typename _H1, typename _H2>
673 struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
674 _Default_ranged_hash, false>
675 // See PR53067.
676 : public _Hashtable_ebo_helper<0, _ExtractKey>,
677 public _Hashtable_ebo_helper<1, _H1>,
678 public _Hashtable_ebo_helper<2, _H2>
679 {
680 private:
681 typedef _Hashtable_ebo_helper<0, _ExtractKey> _EboExtractKey;
682 typedef _Hashtable_ebo_helper<1, _H1> _EboH1;
683 typedef _Hashtable_ebo_helper<2, _H2> _EboH2;
684
685 public:
686 typedef _H1 hasher;
687
688 hasher
689 hash_function() const
690 { return _M_h1(); }
691
692 protected:
693 // We need the default constructor for the local iterators.
694 _Hash_code_base() = default;
695 _Hash_code_base(const _ExtractKey& __ex,
696 const _H1& __h1, const _H2& __h2,
697 const _Default_ranged_hash&)
698 : _EboExtractKey(__ex), _EboH1(__h1), _EboH2(__h2) { }
699
700 typedef std::size_t _Hash_code_type;
701
702 _Hash_code_type
703 _M_hash_code(const _Key& __k) const
704 { return _M_h1()(__k); }
705
706 std::size_t
707 _M_bucket_index(const _Key&, _Hash_code_type __c,
708 std::size_t __n) const
709 { return _M_h2()(__c, __n); }
710
711 std::size_t
712 _M_bucket_index(const _Hash_node<_Value, false>* __p,
713 std::size_t __n) const
714 { return _M_h2()(_M_h1()(_M_extract()(__p->_M_v)), __n); }
715
716 void
717 _M_store_code(_Hash_node<_Value, false>*, _Hash_code_type) const
718 { }
719
720 void
721 _M_copy_code(_Hash_node<_Value, false>*,
722 const _Hash_node<_Value, false>*) const
723 { }
724
725 void
726 _M_swap(_Hash_code_base& __x)
727 {
728 std::swap(_M_extract(), __x._M_extract());
729 std::swap(_M_h1(), __x._M_h1());
730 std::swap(_M_h2(), __x._M_h2());
731 }
732
733 protected:
734 const _ExtractKey&
735 _M_extract() const { return _EboExtractKey::_S_cget(*this); }
736 _ExtractKey&
737 _M_extract() { return _EboExtractKey::_S_get(*this); }
738 const _H1&
739 _M_h1() const { return _EboH1::_S_cget(*this); }
740 _H1&
741 _M_h1() { return _EboH1::_S_get(*this); }
742 const _H2&
743 _M_h2() const { return _EboH2::_S_cget(*this); }
744 _H2&
745 _M_h2() { return _EboH2::_S_get(*this); }
746 };
747
748 // Specialization: hash function and range-hashing function,
749 // caching hash codes. H is provided but ignored. Provides
750 // typedef and accessor required by TR1.
751 template<typename _Key, typename _Value, typename _ExtractKey,
752 typename _H1, typename _H2>
753 struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
754 _Default_ranged_hash, true>
755 // See PR53067.
756 : public _Hashtable_ebo_helper<0, _ExtractKey>,
757 public _Hashtable_ebo_helper<1, _H1>,
758 public _Hashtable_ebo_helper<2, _H2>
759 {
760 private:
761 typedef _Hashtable_ebo_helper<0, _ExtractKey> _EboExtractKey;
762 typedef _Hashtable_ebo_helper<1, _H1> _EboH1;
763 typedef _Hashtable_ebo_helper<2, _H2> _EboH2;
764
765 public:
766 typedef _H1 hasher;
767
768 hasher
769 hash_function() const
770 { return _M_h1(); }
771
772 protected:
773 _Hash_code_base(const _ExtractKey& __ex,
774 const _H1& __h1, const _H2& __h2,
775 const _Default_ranged_hash&)
776 : _EboExtractKey(__ex), _EboH1(__h1), _EboH2(__h2) { }
777
778 typedef std::size_t _Hash_code_type;
779
780 _Hash_code_type
781 _M_hash_code(const _Key& __k) const
782 { return _M_h1()(__k); }
783
784 std::size_t
785 _M_bucket_index(const _Key&, _Hash_code_type __c,
786 std::size_t __n) const
787 { return _M_h2()(__c, __n); }
788
789 std::size_t
790 _M_bucket_index(const _Hash_node<_Value, true>* __p,
791 std::size_t __n) const
792 { return _M_h2()(__p->_M_hash_code, __n); }
793
794 void
795 _M_store_code(_Hash_node<_Value, true>* __n, _Hash_code_type __c) const
796 { __n->_M_hash_code = __c; }
797
798 void
799 _M_copy_code(_Hash_node<_Value, true>* __to,
800 const _Hash_node<_Value, true>* __from) const
801 { __to->_M_hash_code = __from->_M_hash_code; }
802
803 void
804 _M_swap(_Hash_code_base& __x)
805 {
806 std::swap(_M_extract(), __x._M_extract());
807 std::swap(_M_h1(), __x._M_h1());
808 std::swap(_M_h2(), __x._M_h2());
809 }
810
811 protected:
812 const _ExtractKey&
813 _M_extract() const { return _EboExtractKey::_S_cget(*this); }
814 _ExtractKey&
815 _M_extract() { return _EboExtractKey::_S_get(*this); }
816 const _H1&
817 _M_h1() const { return _EboH1::_S_cget(*this); }
818 _H1&
819 _M_h1() { return _EboH1::_S_get(*this); }
820 const _H2&
821 _M_h2() const { return _EboH2::_S_cget(*this); }
822 _H2&
823 _M_h2() { return _EboH2::_S_get(*this); }
824 };
825
826 template <typename _Key, typename _Value, typename _ExtractKey,
827 typename _Equal, typename _HashCodeType,
828 bool __cache_hash_code>
829 struct _Equal_helper;
830
831 template<typename _Key, typename _Value, typename _ExtractKey,
832 typename _Equal, typename _HashCodeType>
833 struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, true>
834 {
835 static bool
836 _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
837 const _Key& __k, _HashCodeType __c,
838 _Hash_node<_Value, true>* __n)
839 { return __c == __n->_M_hash_code
840 && __eq(__k, __extract(__n->_M_v)); }
841 };
842
843 template<typename _Key, typename _Value, typename _ExtractKey,
844 typename _Equal, typename _HashCodeType>
845 struct _Equal_helper<_Key, _Value, _ExtractKey, _Equal, _HashCodeType, false>
846 {
847 static bool
848 _S_equals(const _Equal& __eq, const _ExtractKey& __extract,
849 const _Key& __k, _HashCodeType,
850 _Hash_node<_Value, false>* __n)
851 { return __eq(__k, __extract(__n->_M_v)); }
852 };
853
854 // Helper class adding management of _Equal functor to _Hash_code_base
855 // type.
856 template<typename _Key, typename _Value,
857 typename _ExtractKey, typename _Equal,
858 typename _H1, typename _H2, typename _Hash,
859 bool __cache_hash_code>
860 struct _Hashtable_base
861 // See PR53067.
862 : public _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash,
863 __cache_hash_code>,
864 public _Hashtable_ebo_helper<0, _Equal>
865 {
866 private:
867 typedef _Hashtable_ebo_helper<0, _Equal> _EboEqual;
868
869 protected:
870 typedef _Hash_code_base<_Key, _Value, _ExtractKey,
871 _H1, _H2, _Hash, __cache_hash_code> _HCBase;
872 typedef typename _HCBase::_Hash_code_type _Hash_code_type;
873
874 _Hashtable_base(const _ExtractKey& __ex,
875 const _H1& __h1, const _H2& __h2,
876 const _Hash& __hash, const _Equal& __eq)
877 : _HCBase(__ex, __h1, __h2, __hash), _EboEqual(__eq) { }
878
879 bool
880 _M_equals(const _Key& __k, _Hash_code_type __c,
881 _Hash_node<_Value, __cache_hash_code>* __n) const
882 {
883 typedef _Equal_helper<_Key, _Value, _ExtractKey,
884 _Equal, _Hash_code_type,
885 __cache_hash_code> _EqualHelper;
886 return _EqualHelper::_S_equals(_M_eq(), this->_M_extract(),
887 __k, __c, __n);
888 }
889
890 void
891 _M_swap(_Hashtable_base& __x)
892 {
893 _HCBase::_M_swap(__x);
894 std::swap(_M_eq(), __x._M_eq());
895 }
896
897 protected:
898 const _Equal&
899 _M_eq() const { return _EboEqual::_S_cget(*this); }
900 _Equal&
901 _M_eq() { return _EboEqual::_S_get(*this); }
902 };
903
904 // Local iterators, used to iterate within a bucket but not between
905 // buckets.
906 template<typename _Key, typename _Value, typename _ExtractKey,
907 typename _H1, typename _H2, typename _Hash,
908 bool __cache_hash_code>
909 struct _Local_iterator_base;
910
911 template<typename _Key, typename _Value, typename _ExtractKey,
912 typename _H1, typename _H2, typename _Hash>
913 struct _Local_iterator_base<_Key, _Value, _ExtractKey,
914 _H1, _H2, _Hash, true>
915 // See PR53067.
916 : public _H2
917 {
918 _Local_iterator_base() = default;
919 _Local_iterator_base(_Hash_node<_Value, true>* __p,
920 std::size_t __bkt, std::size_t __bkt_count)
921 : _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count) { }
922
923 void
924 _M_incr()
925 {
926 _M_cur = _M_cur->_M_next();
927 if (_M_cur)
928 {
929 std::size_t __bkt = _M_h2()(_M_cur->_M_hash_code, _M_bucket_count);
930 if (__bkt != _M_bucket)
931 _M_cur = nullptr;
932 }
933 }
934
935 const _H2& _M_h2() const
936 { return *this; }
937
938 _Hash_node<_Value, true>* _M_cur;
939 std::size_t _M_bucket;
940 std::size_t _M_bucket_count;
941 };
942
943 template<typename _Key, typename _Value, typename _ExtractKey,
944 typename _H1, typename _H2, typename _Hash>
945 struct _Local_iterator_base<_Key, _Value, _ExtractKey,
946 _H1, _H2, _Hash, false>
947 // See PR53067.
948 : public _Hash_code_base<_Key, _Value, _ExtractKey,
949 _H1, _H2, _Hash, false>
950 {
951 _Local_iterator_base() = default;
952 _Local_iterator_base(_Hash_node<_Value, false>* __p,
953 std::size_t __bkt, std::size_t __bkt_count)
954 : _M_cur(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count) { }
955
956 void
957 _M_incr()
958 {
959 _M_cur = _M_cur->_M_next();
960 if (_M_cur)
961 {
962 std::size_t __bkt = this->_M_bucket_index(_M_cur, _M_bucket_count);
963 if (__bkt != _M_bucket)
964 _M_cur = nullptr;
965 }
966 }
967
968 _Hash_node<_Value, false>* _M_cur;
969 std::size_t _M_bucket;
970 std::size_t _M_bucket_count;
971 };
972
973 template<typename _Key, typename _Value, typename _ExtractKey,
974 typename _H1, typename _H2, typename _Hash, bool __cache>
975 inline bool
976 operator==(const _Local_iterator_base<_Key, _Value, _ExtractKey,
977 _H1, _H2, _Hash, __cache>& __x,
978 const _Local_iterator_base<_Key, _Value, _ExtractKey,
979 _H1, _H2, _Hash, __cache>& __y)
980 { return __x._M_cur == __y._M_cur; }
981
982 template<typename _Key, typename _Value, typename _ExtractKey,
983 typename _H1, typename _H2, typename _Hash, bool __cache>
984 inline bool
985 operator!=(const _Local_iterator_base<_Key, _Value, _ExtractKey,
986 _H1, _H2, _Hash, __cache>& __x,
987 const _Local_iterator_base<_Key, _Value, _ExtractKey,
988 _H1, _H2, _Hash, __cache>& __y)
989 { return __x._M_cur != __y._M_cur; }
990
991 template<typename _Key, typename _Value, typename _ExtractKey,
992 typename _H1, typename _H2, typename _Hash,
993 bool __constant_iterators, bool __cache>
994 struct _Local_iterator
995 : public _Local_iterator_base<_Key, _Value, _ExtractKey,
996 _H1, _H2, _Hash, __cache>
997 {
998 typedef _Value value_type;
999 typedef typename std::conditional<__constant_iterators,
1000 const _Value*, _Value*>::type
1001 pointer;
1002 typedef typename std::conditional<__constant_iterators,
1003 const _Value&, _Value&>::type
1004 reference;
1005 typedef std::ptrdiff_t difference_type;
1006 typedef std::forward_iterator_tag iterator_category;
1007
1008 _Local_iterator() = default;
1009
1010 explicit
1011 _Local_iterator(_Hash_node<_Value, __cache>* __p,
1012 std::size_t __bkt, std::size_t __bkt_count)
1013 : _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash,
1014 __cache>(__p, __bkt, __bkt_count)
1015 { }
1016
1017 reference
1018 operator*() const
1019 { return this->_M_cur->_M_v; }
1020
1021 pointer
1022 operator->() const
1023 { return std::__addressof(this->_M_cur->_M_v); }
1024
1025 _Local_iterator&
1026 operator++()
1027 {
1028 this->_M_incr();
1029 return *this;
1030 }
1031
1032 _Local_iterator
1033 operator++(int)
1034 {
1035 _Local_iterator __tmp(*this);
1036 this->_M_incr();
1037 return __tmp;
1038 }
1039 };
1040
1041 template<typename _Key, typename _Value, typename _ExtractKey,
1042 typename _H1, typename _H2, typename _Hash,
1043 bool __constant_iterators, bool __cache>
1044 struct _Local_const_iterator
1045 : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1046 _H1, _H2, _Hash, __cache>
1047 {
1048 typedef _Value value_type;
1049 typedef const _Value* pointer;
1050 typedef const _Value& reference;
1051 typedef std::ptrdiff_t difference_type;
1052 typedef std::forward_iterator_tag iterator_category;
1053
1054 _Local_const_iterator() = default;
1055
1056 explicit
1057 _Local_const_iterator(_Hash_node<_Value, __cache>* __p,
1058 std::size_t __bkt, std::size_t __bkt_count)
1059 : _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash,
1060 __cache>(__p, __bkt, __bkt_count)
1061 { }
1062
1063 _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
1064 _H1, _H2, _Hash,
1065 __constant_iterators,
1066 __cache>& __x)
1067 : _Local_iterator_base<_Key, _Value, _ExtractKey, _H1, _H2, _Hash,
1068 __cache>(__x._M_cur, __x._M_bucket,
1069 __x._M_bucket_count)
1070 { }
1071
1072 reference
1073 operator*() const
1074 { return this->_M_cur->_M_v; }
1075
1076 pointer
1077 operator->() const
1078 { return std::__addressof(this->_M_cur->_M_v); }
1079
1080 _Local_const_iterator&
1081 operator++()
1082 {
1083 this->_M_incr();
1084 return *this;
1085 }
1086
1087 _Local_const_iterator
1088 operator++(int)
1089 {
1090 _Local_const_iterator __tmp(*this);
1091 this->_M_incr();
1092 return __tmp;
1093 }
1094 };
1095
1096
1097 // Class template _Equality_base. This is for implementing equality
1098 // comparison for unordered containers, per N3068, by John Lakos and
1099 // Pablo Halpern. Algorithmically, we follow closely the reference
1100 // implementations therein.
1101 template<typename _ExtractKey, bool __unique_keys,
1102 typename _Hashtable>
1103 struct _Equality_base;
1104
1105 template<typename _ExtractKey, typename _Hashtable>
1106 struct _Equality_base<_ExtractKey, true, _Hashtable>
1107 {
1108 bool _M_equal(const _Hashtable&) const;
1109 };
1110
1111 template<typename _ExtractKey, typename _Hashtable>
1112 bool
1113 _Equality_base<_ExtractKey, true, _Hashtable>::
1114 _M_equal(const _Hashtable& __other) const
1115 {
1116 const _Hashtable* __this = static_cast<const _Hashtable*>(this);
1117
1118 if (__this->size() != __other.size())
1119 return false;
1120
1121 for (auto __itx = __this->begin(); __itx != __this->end(); ++__itx)
1122 {
1123 const auto __ity = __other.find(_ExtractKey()(*__itx));
1124 if (__ity == __other.end() || !bool(*__ity == *__itx))
1125 return false;
1126 }
1127 return true;
1128 }
1129
1130 template<typename _ExtractKey, typename _Hashtable>
1131 struct _Equality_base<_ExtractKey, false, _Hashtable>
1132 {
1133 bool _M_equal(const _Hashtable&) const;
1134
1135 private:
1136 template<typename _Uiterator>
1137 static bool
1138 _S_is_permutation(_Uiterator, _Uiterator, _Uiterator);
1139 };
1140
1141 // See std::is_permutation in N3068.
1142 template<typename _ExtractKey, typename _Hashtable>
1143 template<typename _Uiterator>
1144 bool
1145 _Equality_base<_ExtractKey, false, _Hashtable>::
1146 _S_is_permutation(_Uiterator __first1, _Uiterator __last1,
1147 _Uiterator __first2)
1148 {
1149 for (; __first1 != __last1; ++__first1, ++__first2)
1150 if (!(*__first1 == *__first2))
1151 break;
1152
1153 if (__first1 == __last1)
1154 return true;
1155
1156 _Uiterator __last2 = __first2;
1157 std::advance(__last2, std::distance(__first1, __last1));
1158
1159 for (_Uiterator __it1 = __first1; __it1 != __last1; ++__it1)
1160 {
1161 _Uiterator __tmp = __first1;
1162 while (__tmp != __it1 && !bool(*__tmp == *__it1))
1163 ++__tmp;
1164
1165 // We've seen this one before.
1166 if (__tmp != __it1)
1167 continue;
1168
1169 std::ptrdiff_t __n2 = 0;
1170 for (__tmp = __first2; __tmp != __last2; ++__tmp)
1171 if (*__tmp == *__it1)
1172 ++__n2;
1173
1174 if (!__n2)
1175 return false;
1176
1177 std::ptrdiff_t __n1 = 0;
1178 for (__tmp = __it1; __tmp != __last1; ++__tmp)
1179 if (*__tmp == *__it1)
1180 ++__n1;
1181
1182 if (__n1 != __n2)
1183 return false;
1184 }
1185 return true;
1186 }
1187
1188 template<typename _ExtractKey, typename _Hashtable>
1189 bool
1190 _Equality_base<_ExtractKey, false, _Hashtable>::
1191 _M_equal(const _Hashtable& __other) const
1192 {
1193 const _Hashtable* __this = static_cast<const _Hashtable*>(this);
1194
1195 if (__this->size() != __other.size())
1196 return false;
1197
1198 for (auto __itx = __this->begin(); __itx != __this->end();)
1199 {
1200 const auto __xrange = __this->equal_range(_ExtractKey()(*__itx));
1201 const auto __yrange = __other.equal_range(_ExtractKey()(*__itx));
1202
1203 if (std::distance(__xrange.first, __xrange.second)
1204 != std::distance(__yrange.first, __yrange.second))
1205 return false;
1206
1207 if (!_S_is_permutation(__xrange.first,
1208 __xrange.second,
1209 __yrange.first))
1210 return false;
1211
1212 __itx = __xrange.second;
1213 }
1214 return true;
1215 }
1216
1217 _GLIBCXX_END_NAMESPACE_VERSION
1218 } // namespace __detail
1219 } // namespace std
1220
1221 #endif // _HASHTABLE_POLICY_H
1222