1 // Internal policy header for TR1 unordered_set and unordered_map -*- C++ -*-
2
3 // Copyright (C) 2010-2023 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 tr1/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{tr1/unordered_map, tr1/unordered_set}
29 */
30
31 namespace std _GLIBCXX_VISIBILITY(default)
32 {
33 _GLIBCXX_BEGIN_NAMESPACE_VERSION
34
35 namespace tr1
36 {
37 namespace __detail
38 {
39 // Helper function: return distance(first, last) for forward
40 // iterators, or 0 for input iterators.
41 template<class _Iterator>
42 inline typename std::iterator_traits<_Iterator>::difference_type
43 __distance_fw(_Iterator __first, _Iterator __last,
44 std::input_iterator_tag)
45 { return 0; }
46
47 template<class _Iterator>
48 inline typename std::iterator_traits<_Iterator>::difference_type
49 __distance_fw(_Iterator __first, _Iterator __last,
50 std::forward_iterator_tag)
51 { return std::distance(__first, __last); }
52
53 template<class _Iterator>
54 inline typename std::iterator_traits<_Iterator>::difference_type
55 __distance_fw(_Iterator __first, _Iterator __last)
56 {
57 typedef typename std::iterator_traits<_Iterator>::iterator_category _Tag;
58 return __distance_fw(__first, __last, _Tag());
59 }
60
61 // Auxiliary types used for all instantiations of _Hashtable: nodes
62 // and iterators.
63
64 // Nodes, used to wrap elements stored in the hash table. A policy
65 // template parameter of class template _Hashtable controls whether
66 // nodes also store a hash code. In some cases (e.g. strings) this
67 // may be a performance win.
68 template<typename _Value, bool __cache_hash_code>
69 struct _Hash_node;
70
71 template<typename _Value>
72 struct _Hash_node<_Value, true>
73 {
74 _Value _M_v;
75 std::size_t _M_hash_code;
76 _Hash_node* _M_next;
77 };
78
79 template<typename _Value>
80 struct _Hash_node<_Value, false>
81 {
82 _Value _M_v;
83 _Hash_node* _M_next;
84 };
85
86 // Local iterators, used to iterate within a bucket but not between
87 // buckets.
88 template<typename _Value, bool __cache>
89 struct _Node_iterator_base
90 {
91 _Node_iterator_base(_Hash_node<_Value, __cache>* __p)
92 : _M_cur(__p) { }
93
94 void
95 _M_incr()
96 { _M_cur = _M_cur->_M_next; }
97
98 _Hash_node<_Value, __cache>* _M_cur;
99 };
100
101 template<typename _Value, bool __cache>
102 inline bool
103 operator==(const _Node_iterator_base<_Value, __cache>& __x,
104 const _Node_iterator_base<_Value, __cache>& __y)
105 { return __x._M_cur == __y._M_cur; }
106
107 template<typename _Value, bool __cache>
108 inline bool
109 operator!=(const _Node_iterator_base<_Value, __cache>& __x,
110 const _Node_iterator_base<_Value, __cache>& __y)
111 { return __x._M_cur != __y._M_cur; }
112
113 template<typename _Value, bool __constant_iterators, bool __cache>
114 struct _Node_iterator
115 : public _Node_iterator_base<_Value, __cache>
116 {
117 typedef _Value value_type;
118 typedef typename
119 __gnu_cxx::__conditional_type<__constant_iterators,
120 const _Value*, _Value*>::__type
121 pointer;
122 typedef typename
123 __gnu_cxx::__conditional_type<__constant_iterators,
124 const _Value&, _Value&>::__type
125 reference;
126 typedef std::ptrdiff_t difference_type;
127 typedef std::forward_iterator_tag iterator_category;
128
129 _Node_iterator()
130 : _Node_iterator_base<_Value, __cache>(0) { }
131
132 explicit
133 _Node_iterator(_Hash_node<_Value, __cache>* __p)
134 : _Node_iterator_base<_Value, __cache>(__p) { }
135
136 reference
137 operator*() const
138 { return this->_M_cur->_M_v; }
139
140 pointer
141 operator->() const
142 { return std::__addressof(this->_M_cur->_M_v); }
143
144 _Node_iterator&
145 operator++()
146 {
147 this->_M_incr();
148 return *this;
149 }
150
151 _Node_iterator
152 operator++(int)
153 {
154 _Node_iterator __tmp(*this);
155 this->_M_incr();
156 return __tmp;
157 }
158 };
159
160 template<typename _Value, bool __constant_iterators, bool __cache>
161 struct _Node_const_iterator
162 : public _Node_iterator_base<_Value, __cache>
163 {
164 typedef _Value value_type;
165 typedef const _Value* pointer;
166 typedef const _Value& reference;
167 typedef std::ptrdiff_t difference_type;
168 typedef std::forward_iterator_tag iterator_category;
169
170 _Node_const_iterator()
171 : _Node_iterator_base<_Value, __cache>(0) { }
172
173 explicit
174 _Node_const_iterator(_Hash_node<_Value, __cache>* __p)
175 : _Node_iterator_base<_Value, __cache>(__p) { }
176
177 _Node_const_iterator(const _Node_iterator<_Value, __constant_iterators,
178 __cache>& __x)
179 : _Node_iterator_base<_Value, __cache>(__x._M_cur) { }
180
181 reference
182 operator*() const
183 { return this->_M_cur->_M_v; }
184
185 pointer
186 operator->() const
187 { return std::__addressof(this->_M_cur->_M_v); }
188
189 _Node_const_iterator&
190 operator++()
191 {
192 this->_M_incr();
193 return *this;
194 }
195
196 _Node_const_iterator
197 operator++(int)
198 {
199 _Node_const_iterator __tmp(*this);
200 this->_M_incr();
201 return __tmp;
202 }
203 };
204
205 template<typename _Value, bool __cache>
206 struct _Hashtable_iterator_base
207 {
208 _Hashtable_iterator_base(_Hash_node<_Value, __cache>* __node,
209 _Hash_node<_Value, __cache>** __bucket)
210 : _M_cur_node(__node), _M_cur_bucket(__bucket) { }
211
212 void
213 _M_incr()
214 {
215 _M_cur_node = _M_cur_node->_M_next;
216 if (!_M_cur_node)
217 _M_incr_bucket();
218 }
219
220 void
221 _M_incr_bucket();
222
223 _Hash_node<_Value, __cache>* _M_cur_node;
224 _Hash_node<_Value, __cache>** _M_cur_bucket;
225 };
226
227 // Global iterators, used for arbitrary iteration within a hash
228 // table. Larger and more expensive than local iterators.
229 template<typename _Value, bool __cache>
230 void
231 _Hashtable_iterator_base<_Value, __cache>::
232 _M_incr_bucket()
233 {
234 ++_M_cur_bucket;
235
236 // This loop requires the bucket array to have a non-null sentinel.
237 while (!*_M_cur_bucket)
238 ++_M_cur_bucket;
239 _M_cur_node = *_M_cur_bucket;
240 }
241
242 template<typename _Value, bool __cache>
243 inline bool
244 operator==(const _Hashtable_iterator_base<_Value, __cache>& __x,
245 const _Hashtable_iterator_base<_Value, __cache>& __y)
246 { return __x._M_cur_node == __y._M_cur_node; }
247
248 template<typename _Value, bool __cache>
249 inline bool
250 operator!=(const _Hashtable_iterator_base<_Value, __cache>& __x,
251 const _Hashtable_iterator_base<_Value, __cache>& __y)
252 { return __x._M_cur_node != __y._M_cur_node; }
253
254 template<typename _Value, bool __constant_iterators, bool __cache>
255 struct _Hashtable_iterator
256 : public _Hashtable_iterator_base<_Value, __cache>
257 {
258 typedef _Value value_type;
259 typedef typename
260 __gnu_cxx::__conditional_type<__constant_iterators,
261 const _Value*, _Value*>::__type
262 pointer;
263 typedef typename
264 __gnu_cxx::__conditional_type<__constant_iterators,
265 const _Value&, _Value&>::__type
266 reference;
267 typedef std::ptrdiff_t difference_type;
268 typedef std::forward_iterator_tag iterator_category;
269
270 _Hashtable_iterator()
271 : _Hashtable_iterator_base<_Value, __cache>(0, 0) { }
272
273 _Hashtable_iterator(_Hash_node<_Value, __cache>* __p,
274 _Hash_node<_Value, __cache>** __b)
275 : _Hashtable_iterator_base<_Value, __cache>(__p, __b) { }
276
277 explicit
278 _Hashtable_iterator(_Hash_node<_Value, __cache>** __b)
279 : _Hashtable_iterator_base<_Value, __cache>(*__b, __b) { }
280
281 reference
282 operator*() const
283 { return this->_M_cur_node->_M_v; }
284
285 pointer
286 operator->() const
287 { return std::__addressof(this->_M_cur_node->_M_v); }
288
289 _Hashtable_iterator&
290 operator++()
291 {
292 this->_M_incr();
293 return *this;
294 }
295
296 _Hashtable_iterator
297 operator++(int)
298 {
299 _Hashtable_iterator __tmp(*this);
300 this->_M_incr();
301 return __tmp;
302 }
303 };
304
305 template<typename _Value, bool __constant_iterators, bool __cache>
306 struct _Hashtable_const_iterator
307 : public _Hashtable_iterator_base<_Value, __cache>
308 {
309 typedef _Value value_type;
310 typedef const _Value* pointer;
311 typedef const _Value& reference;
312 typedef std::ptrdiff_t difference_type;
313 typedef std::forward_iterator_tag iterator_category;
314
315 _Hashtable_const_iterator()
316 : _Hashtable_iterator_base<_Value, __cache>(0, 0) { }
317
318 _Hashtable_const_iterator(_Hash_node<_Value, __cache>* __p,
319 _Hash_node<_Value, __cache>** __b)
320 : _Hashtable_iterator_base<_Value, __cache>(__p, __b) { }
321
322 explicit
323 _Hashtable_const_iterator(_Hash_node<_Value, __cache>** __b)
324 : _Hashtable_iterator_base<_Value, __cache>(*__b, __b) { }
325
326 _Hashtable_const_iterator(const _Hashtable_iterator<_Value,
327 __constant_iterators, __cache>& __x)
328 : _Hashtable_iterator_base<_Value, __cache>(__x._M_cur_node,
329 __x._M_cur_bucket) { }
330
331 reference
332 operator*() const
333 { return this->_M_cur_node->_M_v; }
334
335 pointer
336 operator->() const
337 { return std::__addressof(this->_M_cur_node->_M_v); }
338
339 _Hashtable_const_iterator&
340 operator++()
341 {
342 this->_M_incr();
343 return *this;
344 }
345
346 _Hashtable_const_iterator
347 operator++(int)
348 {
349 _Hashtable_const_iterator __tmp(*this);
350 this->_M_incr();
351 return __tmp;
352 }
353 };
354
355
356 // Many of class template _Hashtable's template parameters are policy
357 // classes. These are defaults for the policies.
358
359 // Default range hashing function: use division to fold a large number
360 // into the range [0, N).
361 struct _Mod_range_hashing
362 {
363 typedef std::size_t first_argument_type;
364 typedef std::size_t second_argument_type;
365 typedef std::size_t result_type;
366
367 result_type
368 operator()(first_argument_type __num, second_argument_type __den) const
369 { return __num % __den; }
370 };
371
372 // Default ranged hash function H. In principle it should be a
373 // function object composed from objects of type H1 and H2 such that
374 // h(k, N) = h2(h1(k), N), but that would mean making extra copies of
375 // h1 and h2. So instead we'll just use a tag to tell class template
376 // hashtable to do that composition.
377 struct _Default_ranged_hash { };
378
379 // Default value for rehash policy. Bucket size is (usually) the
380 // smallest prime that keeps the load factor small enough.
381 struct _Prime_rehash_policy
382 {
383 _Prime_rehash_policy(float __z = 1.0)
384 : _M_max_load_factor(__z), _M_growth_factor(2.f), _M_next_resize(0) { }
385
386 float
387 max_load_factor() const
388 { return _M_max_load_factor; }
389
390 // Return a bucket size no smaller than n.
391 std::size_t
392 _M_next_bkt(std::size_t __n) const;
393
394 // Return a bucket count appropriate for n elements
395 std::size_t
396 _M_bkt_for_elements(std::size_t __n) const;
397
398 // __n_bkt is current bucket count, __n_elt is current element count,
399 // and __n_ins is number of elements to be inserted. Do we need to
400 // increase bucket count? If so, return make_pair(true, n), where n
401 // is the new bucket count. If not, return make_pair(false, 0).
402 std::pair<bool, std::size_t>
403 _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
404 std::size_t __n_ins) const;
405
406 enum { _S_n_primes = sizeof(unsigned long) != 8 ? 256 : 256 + 48 };
407
408 float _M_max_load_factor;
409 float _M_growth_factor;
410 mutable std::size_t _M_next_resize;
411 };
412
413 extern const unsigned long __prime_list[];
414
415 // XXX This is a hack. There's no good reason for any of
416 // _Prime_rehash_policy's member functions to be inline.
417
418 // Return a prime no smaller than n.
419 inline std::size_t
420 _Prime_rehash_policy::
421 _M_next_bkt(std::size_t __n) const
422 {
423 // Don't include the last prime in the search, so that anything
424 // higher than the second-to-last prime returns a past-the-end
425 // iterator that can be dereferenced to get the last prime.
426 const unsigned long* __p
427 = std::lower_bound(__prime_list, __prime_list + _S_n_primes - 1, __n);
428 _M_next_resize =
429 static_cast<std::size_t>(__builtin_ceil(*__p * _M_max_load_factor));
430 return *__p;
431 }
432
433 // Return the smallest prime p such that alpha p >= n, where alpha
434 // is the load factor.
435 inline std::size_t
436 _Prime_rehash_policy::
437 _M_bkt_for_elements(std::size_t __n) const
438 {
439 const float __min_bkts = __n / _M_max_load_factor;
440 return _M_next_bkt(__builtin_ceil(__min_bkts));
441 }
442
443 // Finds the smallest prime p such that alpha p > __n_elt + __n_ins.
444 // If p > __n_bkt, return make_pair(true, p); otherwise return
445 // make_pair(false, 0). In principle this isn't very different from
446 // _M_bkt_for_elements.
447
448 // The only tricky part is that we're caching the element count at
449 // which we need to rehash, so we don't have to do a floating-point
450 // multiply for every insertion.
451
452 inline std::pair<bool, std::size_t>
453 _Prime_rehash_policy::
454 _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
455 std::size_t __n_ins) const
456 {
457 if (__n_elt + __n_ins > _M_next_resize)
458 {
459 float __min_bkts = ((float(__n_ins) + float(__n_elt))
460 / _M_max_load_factor);
461 if (__min_bkts > __n_bkt)
462 {
463 __min_bkts = std::max(__min_bkts, _M_growth_factor * __n_bkt);
464 return std::make_pair(true,
465 _M_next_bkt(__builtin_ceil(__min_bkts)));
466 }
467 else
468 {
469 _M_next_resize = static_cast<std::size_t>
470 (__builtin_ceil(__n_bkt * _M_max_load_factor));
471 return std::make_pair(false, 0);
472 }
473 }
474 else
475 return std::make_pair(false, 0);
476 }
477
478 // Base classes for std::tr1::_Hashtable. We define these base
479 // classes because in some cases we want to do different things
480 // depending on the value of a policy class. In some cases the
481 // policy class affects which member functions and nested typedefs
482 // are defined; we handle that by specializing base class templates.
483 // Several of the base class templates need to access other members
484 // of class template _Hashtable, so we use the "curiously recurring
485 // template pattern" for them.
486
487 // class template _Map_base. If the hashtable has a value type of the
488 // form pair<T1, T2> and a key extraction policy that returns the
489 // first part of the pair, the hashtable gets a mapped_type typedef.
490 // If it satisfies those criteria and also has unique keys, then it
491 // also gets an operator[].
492 template<typename _Key, typename _Value, typename _Ex, bool __unique,
493 typename _Hashtable>
494 struct _Map_base { };
495
496 template<typename _Key, typename _Pair, typename _Hashtable>
497 struct _Map_base<_Key, _Pair, std::_Select1st<_Pair>, false, _Hashtable>
498 {
499 typedef typename _Pair::second_type mapped_type;
500 };
501
502 template<typename _Key, typename _Pair, typename _Hashtable>
503 struct _Map_base<_Key, _Pair, std::_Select1st<_Pair>, true, _Hashtable>
504 {
505 typedef typename _Pair::second_type mapped_type;
506
507 mapped_type&
508 operator[](const _Key& __k);
509 };
510
511 template<typename _Key, typename _Pair, typename _Hashtable>
512 typename _Map_base<_Key, _Pair, std::_Select1st<_Pair>,
513 true, _Hashtable>::mapped_type&
514 _Map_base<_Key, _Pair, std::_Select1st<_Pair>, true, _Hashtable>::
515 operator[](const _Key& __k)
516 {
517 _Hashtable* __h = static_cast<_Hashtable*>(this);
518 typename _Hashtable::_Hash_code_type __code = __h->_M_hash_code(__k);
519 std::size_t __n = __h->_M_bucket_index(__k, __code,
520 __h->_M_bucket_count);
521
522 typename _Hashtable::_Node* __p =
523 __h->_M_find_node(__h->_M_buckets[__n], __k, __code);
524 if (!__p)
525 return __h->_M_insert_bucket(std::make_pair(__k, mapped_type()),
526 __n, __code)->second;
527 return (__p->_M_v).second;
528 }
529
530 // class template _Rehash_base. Give hashtable the max_load_factor
531 // functions iff the rehash policy is _Prime_rehash_policy.
532 template<typename _RehashPolicy, typename _Hashtable>
533 struct _Rehash_base { };
534
535 template<typename _Hashtable>
536 struct _Rehash_base<_Prime_rehash_policy, _Hashtable>
537 {
538 float
539 max_load_factor() const
540 {
541 const _Hashtable* __this = static_cast<const _Hashtable*>(this);
542 return __this->__rehash_policy().max_load_factor();
543 }
544
545 void
546 max_load_factor(float __z)
547 {
548 _Hashtable* __this = static_cast<_Hashtable*>(this);
549 __this->__rehash_policy(_Prime_rehash_policy(__z));
550 }
551 };
552
553 // Class template _Hash_code_base. Encapsulates two policy issues that
554 // aren't quite orthogonal.
555 // (1) the difference between using a ranged hash function and using
556 // the combination of a hash function and a range-hashing function.
557 // In the former case we don't have such things as hash codes, so
558 // we have a dummy type as placeholder.
559 // (2) Whether or not we cache hash codes. Caching hash codes is
560 // meaningless if we have a ranged hash function.
561 // We also put the key extraction and equality comparison function
562 // objects here, for convenience.
563
564 // Primary template: unused except as a hook for specializations.
565 template<typename _Key, typename _Value,
566 typename _ExtractKey, typename _Equal,
567 typename _H1, typename _H2, typename _Hash,
568 bool __cache_hash_code>
569 struct _Hash_code_base;
570
571 // Specialization: ranged hash function, no caching hash codes. H1
572 // and H2 are provided but ignored. We define a dummy hash code type.
573 template<typename _Key, typename _Value,
574 typename _ExtractKey, typename _Equal,
575 typename _H1, typename _H2, typename _Hash>
576 struct _Hash_code_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2,
577 _Hash, false>
578 {
579 protected:
580 _Hash_code_base(const _ExtractKey& __ex, const _Equal& __eq,
581 const _H1&, const _H2&, const _Hash& __h)
582 : _M_extract(__ex), _M_eq(__eq), _M_ranged_hash(__h) { }
583
584 typedef void* _Hash_code_type;
585
586 _Hash_code_type
587 _M_hash_code(const _Key& __key) const
588 { return 0; }
589
590 std::size_t
591 _M_bucket_index(const _Key& __k, _Hash_code_type,
592 std::size_t __n) const
593 { return _M_ranged_hash(__k, __n); }
594
595 std::size_t
596 _M_bucket_index(const _Hash_node<_Value, false>* __p,
597 std::size_t __n) const
598 { return _M_ranged_hash(_M_extract(__p->_M_v), __n); }
599
600 bool
601 _M_compare(const _Key& __k, _Hash_code_type,
602 _Hash_node<_Value, false>* __n) const
603 { return _M_eq(__k, _M_extract(__n->_M_v)); }
604
605 void
606 _M_store_code(_Hash_node<_Value, false>*, _Hash_code_type) const
607 { }
608
609 void
610 _M_copy_code(_Hash_node<_Value, false>*,
611 const _Hash_node<_Value, false>*) const
612 { }
613
614 void
615 _M_swap(_Hash_code_base& __x)
616 {
617 std::swap(_M_extract, __x._M_extract);
618 std::swap(_M_eq, __x._M_eq);
619 std::swap(_M_ranged_hash, __x._M_ranged_hash);
620 }
621
622 protected:
623 _ExtractKey _M_extract;
624 _Equal _M_eq;
625 _Hash _M_ranged_hash;
626 };
627
628
629 // No specialization for ranged hash function while caching hash codes.
630 // That combination is meaningless, and trying to do it is an error.
631
632
633 // Specialization: ranged hash function, cache hash codes. This
634 // combination is meaningless, so we provide only a declaration
635 // and no definition.
636 template<typename _Key, typename _Value,
637 typename _ExtractKey, typename _Equal,
638 typename _H1, typename _H2, typename _Hash>
639 struct _Hash_code_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2,
640 _Hash, true>;
641
642 // Specialization: hash function and range-hashing function, no
643 // caching of hash codes. H is provided but ignored. Provides
644 // typedef and accessor required by TR1.
645 template<typename _Key, typename _Value,
646 typename _ExtractKey, typename _Equal,
647 typename _H1, typename _H2>
648 struct _Hash_code_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2,
649 _Default_ranged_hash, false>
650 {
651 typedef _H1 hasher;
652
653 hasher
654 hash_function() const
655 { return _M_h1; }
656
657 protected:
658 _Hash_code_base(const _ExtractKey& __ex, const _Equal& __eq,
659 const _H1& __h1, const _H2& __h2,
660 const _Default_ranged_hash&)
661 : _M_extract(__ex), _M_eq(__eq), _M_h1(__h1), _M_h2(__h2) { }
662
663 typedef std::size_t _Hash_code_type;
664
665 _Hash_code_type
666 _M_hash_code(const _Key& __k) const
667 { return _M_h1(__k); }
668
669 std::size_t
670 _M_bucket_index(const _Key&, _Hash_code_type __c,
671 std::size_t __n) const
672 { return _M_h2(__c, __n); }
673
674 std::size_t
675 _M_bucket_index(const _Hash_node<_Value, false>* __p,
676 std::size_t __n) const
677 { return _M_h2(_M_h1(_M_extract(__p->_M_v)), __n); }
678
679 bool
680 _M_compare(const _Key& __k, _Hash_code_type,
681 _Hash_node<_Value, false>* __n) const
682 { return _M_eq(__k, _M_extract(__n->_M_v)); }
683
684 void
685 _M_store_code(_Hash_node<_Value, false>*, _Hash_code_type) const
686 { }
687
688 void
689 _M_copy_code(_Hash_node<_Value, false>*,
690 const _Hash_node<_Value, false>*) const
691 { }
692
693 void
694 _M_swap(_Hash_code_base& __x)
695 {
696 std::swap(_M_extract, __x._M_extract);
697 std::swap(_M_eq, __x._M_eq);
698 std::swap(_M_h1, __x._M_h1);
699 std::swap(_M_h2, __x._M_h2);
700 }
701
702 protected:
703 _ExtractKey _M_extract;
704 _Equal _M_eq;
705 _H1 _M_h1;
706 _H2 _M_h2;
707 };
708
709 // Specialization: hash function and range-hashing function,
710 // caching hash codes. H is provided but ignored. Provides
711 // typedef and accessor required by TR1.
712 template<typename _Key, typename _Value,
713 typename _ExtractKey, typename _Equal,
714 typename _H1, typename _H2>
715 struct _Hash_code_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2,
716 _Default_ranged_hash, true>
717 {
718 typedef _H1 hasher;
719
720 hasher
721 hash_function() const
722 { return _M_h1; }
723
724 protected:
725 _Hash_code_base(const _ExtractKey& __ex, const _Equal& __eq,
726 const _H1& __h1, const _H2& __h2,
727 const _Default_ranged_hash&)
728 : _M_extract(__ex), _M_eq(__eq), _M_h1(__h1), _M_h2(__h2) { }
729
730 typedef std::size_t _Hash_code_type;
731
732 _Hash_code_type
733 _M_hash_code(const _Key& __k) const
734 { return _M_h1(__k); }
735
736 std::size_t
737 _M_bucket_index(const _Key&, _Hash_code_type __c,
738 std::size_t __n) const
739 { return _M_h2(__c, __n); }
740
741 std::size_t
742 _M_bucket_index(const _Hash_node<_Value, true>* __p,
743 std::size_t __n) const
744 { return _M_h2(__p->_M_hash_code, __n); }
745
746 bool
747 _M_compare(const _Key& __k, _Hash_code_type __c,
748 _Hash_node<_Value, true>* __n) const
749 { return __c == __n->_M_hash_code && _M_eq(__k, _M_extract(__n->_M_v)); }
750
751 void
752 _M_store_code(_Hash_node<_Value, true>* __n, _Hash_code_type __c) const
753 { __n->_M_hash_code = __c; }
754
755 void
756 _M_copy_code(_Hash_node<_Value, true>* __to,
757 const _Hash_node<_Value, true>* __from) const
758 { __to->_M_hash_code = __from->_M_hash_code; }
759
760 void
761 _M_swap(_Hash_code_base& __x)
762 {
763 std::swap(_M_extract, __x._M_extract);
764 std::swap(_M_eq, __x._M_eq);
765 std::swap(_M_h1, __x._M_h1);
766 std::swap(_M_h2, __x._M_h2);
767 }
768
769 protected:
770 _ExtractKey _M_extract;
771 _Equal _M_eq;
772 _H1 _M_h1;
773 _H2 _M_h2;
774 };
775 } // namespace __detail
776 }
777
778 _GLIBCXX_END_NAMESPACE_VERSION
779 }