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
38namespace 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
49namespace __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>
64 inline typename std::iterator_traits<_Iterator>::difference_type
65 __distance_fw(_Iterator __first, _Iterator __last,
66 std::input_iterator_tag)
67 { return __first != __last ? 1 : 0; }
68
69 template<class _Iterator>
70 inline typename std::iterator_traits<_Iterator>::difference_type
71 __distance_fw(_Iterator __first, _Iterator __last,
72 std::forward_iterator_tag)
73 { return std::distance(__first, __last); }
74
75 template<class _Iterator>
76 inline typename std::iterator_traits<_Iterator>::difference_type
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).
466 std::pair<bool, std::size_t>
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 {
507 using __gnu_cxx::__int_traits;
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).
575 std::pair<bool, std::size_t>
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,
709 std::piecewise_construct,
710 std::tuple<const key_type&>(__k),
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,
736 std::piecewise_construct,
737 std::forward_as_tuple(std::move(__k)),
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,
836 std::pair<iterator, bool>,
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>
856 std::pair<iterator, bool>
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,
867 std::piecewise_construct,
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>
1023 using __is_cons = std::is_constructible<value_type, _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
1952