libstdc++
hashtable_policy.h
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1// Internal policy header for unordered_set and unordered_map -*- C++ -*-
2
3// Copyright (C) 2010-2021 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25/** @file bits/hashtable_policy.h
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly.
28 * @headername{unordered_map,unordered_set}
29 */
30
31#ifndef _HASHTABLE_POLICY_H
32#define _HASHTABLE_POLICY_H 1
33
34#include <tuple> // for std::tuple, std::forward_as_tuple
35#include <bits/stl_algobase.h> // for std::min, std::is_permutation.
36#include <ext/numeric_traits.h> // for __gnu_cxx::__int_traits
37
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>
65 __distance_fw(_Iterator __first, _Iterator __last,
67 { return __first != __last ? 1 : 0; }
68
69 template<class _Iterator>
71 __distance_fw(_Iterator __first, _Iterator __last,
73 { return std::distance(__first, __last); }
74
75 template<class _Iterator>
77 __distance_fw(_Iterator __first, _Iterator __last)
78 { return __distance_fw(__first, __last,
79 std::__iterator_category(__first)); }
80
81 struct _Identity
82 {
83 template<typename _Tp>
84 _Tp&&
85 operator()(_Tp&& __x) const noexcept
86 { return std::forward<_Tp>(__x); }
87 };
88
89 struct _Select1st
90 {
91 template<typename _Tp>
92 auto
93 operator()(_Tp&& __x) const noexcept
94 -> decltype(std::get<0>(std::forward<_Tp>(__x)))
95 { return std::get<0>(std::forward<_Tp>(__x)); }
96 };
97
98 template<typename _NodeAlloc>
99 struct _Hashtable_alloc;
100
101 // Functor recycling a pool of nodes and using allocation once the pool is
102 // empty.
103 template<typename _NodeAlloc>
104 struct _ReuseOrAllocNode
105 {
106 private:
107 using __node_alloc_type = _NodeAlloc;
108 using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>;
109 using __node_alloc_traits =
110 typename __hashtable_alloc::__node_alloc_traits;
111 using __node_type = typename __hashtable_alloc::__node_type;
112
113 public:
114 _ReuseOrAllocNode(__node_type* __nodes, __hashtable_alloc& __h)
115 : _M_nodes(__nodes), _M_h(__h) { }
116 _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete;
117
118 ~_ReuseOrAllocNode()
119 { _M_h._M_deallocate_nodes(_M_nodes); }
120
121 template<typename _Arg>
122 __node_type*
123 operator()(_Arg&& __arg) const
124 {
125 if (_M_nodes)
126 {
127 __node_type* __node = _M_nodes;
128 _M_nodes = _M_nodes->_M_next();
129 __node->_M_nxt = nullptr;
130 auto& __a = _M_h._M_node_allocator();
131 __node_alloc_traits::destroy(__a, __node->_M_valptr());
132 __try
133 {
134 __node_alloc_traits::construct(__a, __node->_M_valptr(),
135 std::forward<_Arg>(__arg));
136 }
137 __catch(...)
138 {
139 _M_h._M_deallocate_node_ptr(__node);
140 __throw_exception_again;
141 }
142 return __node;
143 }
144 return _M_h._M_allocate_node(std::forward<_Arg>(__arg));
145 }
146
147 private:
148 mutable __node_type* _M_nodes;
149 __hashtable_alloc& _M_h;
150 };
151
152 // Functor similar to the previous one but without any pool of nodes to
153 // recycle.
154 template<typename _NodeAlloc>
155 struct _AllocNode
156 {
157 private:
158 using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>;
159 using __node_type = typename __hashtable_alloc::__node_type;
160
161 public:
162 _AllocNode(__hashtable_alloc& __h)
163 : _M_h(__h) { }
164
165 template<typename _Arg>
166 __node_type*
167 operator()(_Arg&& __arg) const
168 { return _M_h._M_allocate_node(std::forward<_Arg>(__arg)); }
169
170 private:
171 __hashtable_alloc& _M_h;
172 };
173
174 // Auxiliary types used for all instantiations of _Hashtable nodes
175 // and iterators.
176
177 /**
178 * struct _Hashtable_traits
179 *
180 * Important traits for hash tables.
181 *
182 * @tparam _Cache_hash_code Boolean value. True if the value of
183 * the hash function is stored along with the value. This is a
184 * time-space tradeoff. Storing it may improve lookup speed by
185 * reducing the number of times we need to call the _Hash or _Equal
186 * functors.
187 *
188 * @tparam _Constant_iterators Boolean value. True if iterator and
189 * const_iterator are both constant iterator types. This is true
190 * for unordered_set and unordered_multiset, false for
191 * unordered_map and unordered_multimap.
192 *
193 * @tparam _Unique_keys Boolean value. True if the return value
194 * of _Hashtable::count(k) is always at most one, false if it may
195 * be an arbitrary number. This is true for unordered_set and
196 * unordered_map, false for unordered_multiset and
197 * unordered_multimap.
198 */
199 template<bool _Cache_hash_code, bool _Constant_iterators, bool _Unique_keys>
200 struct _Hashtable_traits
201 {
202 using __hash_cached = __bool_constant<_Cache_hash_code>;
203 using __constant_iterators = __bool_constant<_Constant_iterators>;
204 using __unique_keys = __bool_constant<_Unique_keys>;
205 };
206
207 /**
208 * struct _Hash_node_base
209 *
210 * Nodes, used to wrap elements stored in the hash table. A policy
211 * template parameter of class template _Hashtable controls whether
212 * nodes also store a hash code. In some cases (e.g. strings) this
213 * may be a performance win.
214 */
215 struct _Hash_node_base
216 {
217 _Hash_node_base* _M_nxt;
218
219 _Hash_node_base() noexcept : _M_nxt() { }
220
221 _Hash_node_base(_Hash_node_base* __next) noexcept : _M_nxt(__next) { }
222 };
223
224 /**
225 * struct _Hash_node_value_base
226 *
227 * Node type with the value to store.
228 */
229 template<typename _Value>
230 struct _Hash_node_value_base
231 {
232 typedef _Value value_type;
233
234 __gnu_cxx::__aligned_buffer<_Value> _M_storage;
235
236 [[__gnu__::__always_inline__]]
237 _Value*
238 _M_valptr() noexcept
239 { return _M_storage._M_ptr(); }
240
241 [[__gnu__::__always_inline__]]
242 const _Value*
243 _M_valptr() const noexcept
244 { return _M_storage._M_ptr(); }
245
246 [[__gnu__::__always_inline__]]
247 _Value&
248 _M_v() noexcept
249 { return *_M_valptr(); }
250
251 [[__gnu__::__always_inline__]]
252 const _Value&
253 _M_v() const noexcept
254 { return *_M_valptr(); }
255 };
256
257 /**
258 * Primary template struct _Hash_node_code_cache.
259 */
260 template<bool _Cache_hash_code>
261 struct _Hash_node_code_cache
262 { };
263
264 /**
265 * Specialization for node with cache, struct _Hash_node_code_cache.
266 */
267 template<>
268 struct _Hash_node_code_cache<true>
269 { std::size_t _M_hash_code; };
270
271 template<typename _Value, bool _Cache_hash_code>
272 struct _Hash_node_value
273 : _Hash_node_value_base<_Value>
274 , _Hash_node_code_cache<_Cache_hash_code>
275 { };
276
277 /**
278 * Primary template struct _Hash_node.
279 */
280 template<typename _Value, bool _Cache_hash_code>
281 struct _Hash_node
282 : _Hash_node_base
283 , _Hash_node_value<_Value, _Cache_hash_code>
284 {
285 _Hash_node*
286 _M_next() const noexcept
287 { return static_cast<_Hash_node*>(this->_M_nxt); }
288 };
289
290 /// Base class for node iterators.
291 template<typename _Value, bool _Cache_hash_code>
292 struct _Node_iterator_base
293 {
294 using __node_type = _Hash_node<_Value, _Cache_hash_code>;
295
296 __node_type* _M_cur;
297
298 _Node_iterator_base() : _M_cur(nullptr) { }
299 _Node_iterator_base(__node_type* __p) noexcept
300 : _M_cur(__p) { }
301
302 void
303 _M_incr() noexcept
304 { _M_cur = _M_cur->_M_next(); }
305
306 friend bool
307 operator==(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
308 noexcept
309 { return __x._M_cur == __y._M_cur; }
310
311#if __cpp_impl_three_way_comparison < 201907L
312 friend bool
313 operator!=(const _Node_iterator_base& __x, const _Node_iterator_base& __y)
314 noexcept
315 { return __x._M_cur != __y._M_cur; }
316#endif
317 };
318
319 /// Node iterators, used to iterate through all the hashtable.
320 template<typename _Value, bool __constant_iterators, bool __cache>
321 struct _Node_iterator
322 : public _Node_iterator_base<_Value, __cache>
323 {
324 private:
325 using __base_type = _Node_iterator_base<_Value, __cache>;
326 using __node_type = typename __base_type::__node_type;
327
328 public:
329 typedef _Value value_type;
330 typedef std::ptrdiff_t difference_type;
331 typedef std::forward_iterator_tag iterator_category;
332
333 using pointer = typename std::conditional<__constant_iterators,
334 const value_type*, value_type*>::type;
335
336 using reference = typename std::conditional<__constant_iterators,
337 const value_type&, value_type&>::type;
338
339 _Node_iterator() = default;
340
341 explicit
342 _Node_iterator(__node_type* __p) noexcept
343 : __base_type(__p) { }
344
345 reference
346 operator*() const noexcept
347 { return this->_M_cur->_M_v(); }
348
349 pointer
350 operator->() const noexcept
351 { return this->_M_cur->_M_valptr(); }
352
353 _Node_iterator&
354 operator++() noexcept
355 {
356 this->_M_incr();
357 return *this;
358 }
359
360 _Node_iterator
361 operator++(int) noexcept
362 {
363 _Node_iterator __tmp(*this);
364 this->_M_incr();
365 return __tmp;
366 }
367 };
368
369 /// Node const_iterators, used to iterate through all the hashtable.
370 template<typename _Value, bool __constant_iterators, bool __cache>
371 struct _Node_const_iterator
372 : public _Node_iterator_base<_Value, __cache>
373 {
374 private:
375 using __base_type = _Node_iterator_base<_Value, __cache>;
376 using __node_type = typename __base_type::__node_type;
377
378 public:
379 typedef _Value value_type;
380 typedef std::ptrdiff_t difference_type;
381 typedef std::forward_iterator_tag iterator_category;
382
383 typedef const value_type* pointer;
384 typedef const value_type& reference;
385
386 _Node_const_iterator() = default;
387
388 explicit
389 _Node_const_iterator(__node_type* __p) noexcept
390 : __base_type(__p) { }
391
392 _Node_const_iterator(const _Node_iterator<_Value, __constant_iterators,
393 __cache>& __x) noexcept
394 : __base_type(__x._M_cur) { }
395
396 reference
397 operator*() const noexcept
398 { return this->_M_cur->_M_v(); }
399
400 pointer
401 operator->() const noexcept
402 { return this->_M_cur->_M_valptr(); }
403
404 _Node_const_iterator&
405 operator++() noexcept
406 {
407 this->_M_incr();
408 return *this;
409 }
410
411 _Node_const_iterator
412 operator++(int) noexcept
413 {
414 _Node_const_iterator __tmp(*this);
415 this->_M_incr();
416 return __tmp;
417 }
418 };
419
420 // Many of class template _Hashtable's template parameters are policy
421 // classes. These are defaults for the policies.
422
423 /// Default range hashing function: use division to fold a large number
424 /// into the range [0, N).
425 struct _Mod_range_hashing
426 {
427 typedef std::size_t first_argument_type;
428 typedef std::size_t second_argument_type;
429 typedef std::size_t result_type;
430
431 result_type
432 operator()(first_argument_type __num,
433 second_argument_type __den) const noexcept
434 { return __num % __den; }
435 };
436
437 /// Default ranged hash function H. In principle it should be a
438 /// function object composed from objects of type H1 and H2 such that
439 /// h(k, N) = h2(h1(k), N), but that would mean making extra copies of
440 /// h1 and h2. So instead we'll just use a tag to tell class template
441 /// hashtable to do that composition.
442 struct _Default_ranged_hash { };
443
444 /// Default value for rehash policy. Bucket size is (usually) the
445 /// smallest prime that keeps the load factor small enough.
446 struct _Prime_rehash_policy
447 {
448 using __has_load_factor = true_type;
449
450 _Prime_rehash_policy(float __z = 1.0) noexcept
451 : _M_max_load_factor(__z), _M_next_resize(0) { }
452
453 float
454 max_load_factor() const noexcept
455 { return _M_max_load_factor; }
456
457 // Return a bucket size no smaller than n.
458 std::size_t
459 _M_next_bkt(std::size_t __n) const;
460
461 // Return a bucket count appropriate for n elements
462 std::size_t
463 _M_bkt_for_elements(std::size_t __n) const
464 { return __builtin_ceil(__n / (double)_M_max_load_factor); }
465
466 // __n_bkt is current bucket count, __n_elt is current element count,
467 // and __n_ins is number of elements to be inserted. Do we need to
468 // increase bucket count? If so, return make_pair(true, n), where n
469 // is the new bucket count. If not, return make_pair(false, 0).
471 _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
472 std::size_t __n_ins) const;
473
474 typedef std::size_t _State;
475
476 _State
477 _M_state() const
478 { return _M_next_resize; }
479
480 void
481 _M_reset() noexcept
482 { _M_next_resize = 0; }
483
484 void
485 _M_reset(_State __state)
486 { _M_next_resize = __state; }
487
488 static const std::size_t _S_growth_factor = 2;
489
490 float _M_max_load_factor;
491 mutable std::size_t _M_next_resize;
492 };
493
494 /// Range hashing function assuming that second arg is a power of 2.
495 struct _Mask_range_hashing
496 {
497 typedef std::size_t first_argument_type;
498 typedef std::size_t second_argument_type;
499 typedef std::size_t result_type;
500
501 result_type
502 operator()(first_argument_type __num,
503 second_argument_type __den) const noexcept
504 { return __num & (__den - 1); }
505 };
506
507 /// Compute closest power of 2 not less than __n
508 inline std::size_t
509 __clp2(std::size_t __n) noexcept
510 {
512 // Equivalent to return __n ? std::bit_ceil(__n) : 0;
513 if (__n < 2)
514 return __n;
515 const unsigned __lz = sizeof(size_t) > sizeof(long)
516 ? __builtin_clzll(__n - 1ull)
517 : __builtin_clzl(__n - 1ul);
518 // Doing two shifts avoids undefined behaviour when __lz == 0.
519 return (size_t(1) << (__int_traits<size_t>::__digits - __lz - 1)) << 1;
520 }
521
522 /// Rehash policy providing power of 2 bucket numbers. Avoids modulo
523 /// operations.
524 struct _Power2_rehash_policy
525 {
526 using __has_load_factor = true_type;
527
528 _Power2_rehash_policy(float __z = 1.0) noexcept
529 : _M_max_load_factor(__z), _M_next_resize(0) { }
530
531 float
532 max_load_factor() const noexcept
533 { return _M_max_load_factor; }
534
535 // Return a bucket size no smaller than n (as long as n is not above the
536 // highest power of 2).
537 std::size_t
538 _M_next_bkt(std::size_t __n) noexcept
539 {
540 if (__n == 0)
541 // Special case on container 1st initialization with 0 bucket count
542 // hint. We keep _M_next_resize to 0 to make sure that next time we
543 // want to add an element allocation will take place.
544 return 1;
545
546 const auto __max_width = std::min<size_t>(sizeof(size_t), 8);
547 const auto __max_bkt = size_t(1) << (__max_width * __CHAR_BIT__ - 1);
548 std::size_t __res = __clp2(__n);
549
550 if (__res == 0)
551 __res = __max_bkt;
552 else if (__res == 1)
553 // If __res is 1 we force it to 2 to make sure there will be an
554 // allocation so that nothing need to be stored in the initial
555 // single bucket
556 __res = 2;
557
558 if (__res == __max_bkt)
559 // Set next resize to the max value so that we never try to rehash again
560 // as we already reach the biggest possible bucket number.
561 // Note that it might result in max_load_factor not being respected.
562 _M_next_resize = size_t(-1);
563 else
564 _M_next_resize
565 = __builtin_floor(__res * (double)_M_max_load_factor);
566
567 return __res;
568 }
569
570 // Return a bucket count appropriate for n elements
571 std::size_t
572 _M_bkt_for_elements(std::size_t __n) const noexcept
573 { return __builtin_ceil(__n / (double)_M_max_load_factor); }
574
575 // __n_bkt is current bucket count, __n_elt is current element count,
576 // and __n_ins is number of elements to be inserted. Do we need to
577 // increase bucket count? If so, return make_pair(true, n), where n
578 // is the new bucket count. If not, return make_pair(false, 0).
580 _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt,
581 std::size_t __n_ins) noexcept
582 {
583 if (__n_elt + __n_ins > _M_next_resize)
584 {
585 // If _M_next_resize is 0 it means that we have nothing allocated so
586 // far and that we start inserting elements. In this case we start
587 // with an initial bucket size of 11.
588 double __min_bkts
589 = std::max<std::size_t>(__n_elt + __n_ins, _M_next_resize ? 0 : 11)
590 / (double)_M_max_load_factor;
591 if (__min_bkts >= __n_bkt)
592 return { true,
593 _M_next_bkt(std::max<std::size_t>(__builtin_floor(__min_bkts) + 1,
594 __n_bkt * _S_growth_factor)) };
595
596 _M_next_resize
597 = __builtin_floor(__n_bkt * (double)_M_max_load_factor);
598 return { false, 0 };
599 }
600 else
601 return { false, 0 };
602 }
603
604 typedef std::size_t _State;
605
606 _State
607 _M_state() const noexcept
608 { return _M_next_resize; }
609
610 void
611 _M_reset() noexcept
612 { _M_next_resize = 0; }
613
614 void
615 _M_reset(_State __state) noexcept
616 { _M_next_resize = __state; }
617
618 static const std::size_t _S_growth_factor = 2;
619
620 float _M_max_load_factor;
621 std::size_t _M_next_resize;
622 };
623
624 // Base classes for std::_Hashtable. We define these base classes
625 // because in some cases we want to do different things depending on
626 // the value of a policy class. In some cases the policy class
627 // affects which member functions and nested typedefs are defined;
628 // we handle that by specializing base class templates. Several of
629 // the base class templates need to access other members of class
630 // template _Hashtable, so we use a variant of the "Curiously
631 // Recurring Template Pattern" (CRTP) technique.
632
633 /**
634 * Primary class template _Map_base.
635 *
636 * If the hashtable has a value type of the form pair<T1, T2> and a
637 * key extraction policy (_ExtractKey) that returns the first part
638 * of the pair, the hashtable gets a mapped_type typedef. If it
639 * satisfies those criteria and also has unique keys, then it also
640 * gets an operator[].
641 */
642 template<typename _Key, typename _Value, typename _Alloc,
643 typename _ExtractKey, typename _Equal,
644 typename _Hash, typename _RangeHash, typename _Unused,
645 typename _RehashPolicy, typename _Traits,
646 bool _Unique_keys = _Traits::__unique_keys::value>
647 struct _Map_base { };
648
649 /// Partial specialization, __unique_keys set to false.
650 template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
651 typename _Hash, typename _RangeHash, typename _Unused,
652 typename _RehashPolicy, typename _Traits>
653 struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
654 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
655 {
656 using mapped_type = typename std::tuple_element<1, _Pair>::type;
657 };
658
659 /// Partial specialization, __unique_keys set to true.
660 template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
661 typename _Hash, typename _RangeHash, typename _Unused,
662 typename _RehashPolicy, typename _Traits>
663 struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
664 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
665 {
666 private:
667 using __hashtable_base = _Hashtable_base<_Key, _Pair, _Select1st, _Equal,
668 _Hash, _RangeHash, _Unused,
669 _Traits>;
670
671 using __hashtable = _Hashtable<_Key, _Pair, _Alloc, _Select1st, _Equal,
672 _Hash, _RangeHash,
673 _Unused, _RehashPolicy, _Traits>;
674
675 using __hash_code = typename __hashtable_base::__hash_code;
676
677 public:
678 using key_type = typename __hashtable_base::key_type;
679 using mapped_type = typename std::tuple_element<1, _Pair>::type;
680
681 mapped_type&
682 operator[](const key_type& __k);
683
684 mapped_type&
685 operator[](key_type&& __k);
686
687 // _GLIBCXX_RESOLVE_LIB_DEFECTS
688 // DR 761. unordered_map needs an at() member function.
689 mapped_type&
690 at(const key_type& __k);
691
692 const mapped_type&
693 at(const key_type& __k) const;
694 };
695
696 template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
697 typename _Hash, typename _RangeHash, typename _Unused,
698 typename _RehashPolicy, typename _Traits>
699 auto
700 _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
701 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
702 operator[](const key_type& __k)
703 -> mapped_type&
704 {
705 __hashtable* __h = static_cast<__hashtable*>(this);
706 __hash_code __code = __h->_M_hash_code(__k);
707 std::size_t __bkt = __h->_M_bucket_index(__code);
708 if (auto __node = __h->_M_find_node(__bkt, __k, __code))
709 return __node->_M_v().second;
710
711 typename __hashtable::_Scoped_node __node {
712 __h,
716 };
717 auto __pos
718 = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
719 __node._M_node = nullptr;
720 return __pos->second;
721 }
722
723 template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
724 typename _Hash, typename _RangeHash, typename _Unused,
725 typename _RehashPolicy, typename _Traits>
726 auto
727 _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
728 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
729 operator[](key_type&& __k)
730 -> mapped_type&
731 {
732 __hashtable* __h = static_cast<__hashtable*>(this);
733 __hash_code __code = __h->_M_hash_code(__k);
734 std::size_t __bkt = __h->_M_bucket_index(__code);
735 if (auto __node = __h->_M_find_node(__bkt, __k, __code))
736 return __node->_M_v().second;
737
738 typename __hashtable::_Scoped_node __node {
739 __h,
743 };
744 auto __pos
745 = __h->_M_insert_unique_node(__bkt, __code, __node._M_node);
746 __node._M_node = nullptr;
747 return __pos->second;
748 }
749
750 template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
751 typename _Hash, typename _RangeHash, typename _Unused,
752 typename _RehashPolicy, typename _Traits>
753 auto
754 _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
755 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
756 at(const key_type& __k)
757 -> mapped_type&
758 {
759 __hashtable* __h = static_cast<__hashtable*>(this);
760 auto __ite = __h->find(__k);
761
762 if (!__ite._M_cur)
763 __throw_out_of_range(__N("_Map_base::at"));
764 return __ite->second;
765 }
766
767 template<typename _Key, typename _Pair, typename _Alloc, typename _Equal,
768 typename _Hash, typename _RangeHash, typename _Unused,
769 typename _RehashPolicy, typename _Traits>
770 auto
771 _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal,
772 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
773 at(const key_type& __k) const
774 -> const mapped_type&
775 {
776 const __hashtable* __h = static_cast<const __hashtable*>(this);
777 auto __ite = __h->find(__k);
778
779 if (!__ite._M_cur)
780 __throw_out_of_range(__N("_Map_base::at"));
781 return __ite->second;
782 }
783
784 /**
785 * Primary class template _Insert_base.
786 *
787 * Defines @c insert member functions appropriate to all _Hashtables.
788 */
789 template<typename _Key, typename _Value, typename _Alloc,
790 typename _ExtractKey, typename _Equal,
791 typename _Hash, typename _RangeHash, typename _Unused,
792 typename _RehashPolicy, typename _Traits>
793 struct _Insert_base
794 {
795 protected:
796 using __hashtable_base = _Hashtable_base<_Key, _Value, _ExtractKey,
797 _Equal, _Hash, _RangeHash,
798 _Unused, _Traits>;
799
800 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
801 _Hash, _RangeHash,
802 _Unused, _RehashPolicy, _Traits>;
803
804 using __hash_cached = typename _Traits::__hash_cached;
805 using __constant_iterators = typename _Traits::__constant_iterators;
806
807 using __hashtable_alloc = _Hashtable_alloc<
808 __alloc_rebind<_Alloc, _Hash_node<_Value,
809 __hash_cached::value>>>;
810
811 using value_type = typename __hashtable_base::value_type;
812 using size_type = typename __hashtable_base::size_type;
813
814 using __unique_keys = typename _Traits::__unique_keys;
815 using __node_alloc_type = typename __hashtable_alloc::__node_alloc_type;
816 using __node_gen_type = _AllocNode<__node_alloc_type>;
817
818 __hashtable&
819 _M_conjure_hashtable()
820 { return *(static_cast<__hashtable*>(this)); }
821
822 template<typename _InputIterator, typename _NodeGetter>
823 void
824 _M_insert_range(_InputIterator __first, _InputIterator __last,
825 const _NodeGetter&, true_type __uks);
826
827 template<typename _InputIterator, typename _NodeGetter>
828 void
829 _M_insert_range(_InputIterator __first, _InputIterator __last,
830 const _NodeGetter&, false_type __uks);
831
832 public:
833 using iterator = _Node_iterator<_Value, __constant_iterators::value,
834 __hash_cached::value>;
835
836 using const_iterator = _Node_const_iterator<_Value, __constant_iterators::value,
837 __hash_cached::value>;
838
839 using __ireturn_type = typename std::conditional<__unique_keys::value,
841 iterator>::type;
842
843 __ireturn_type
844 insert(const value_type& __v)
845 {
846 __hashtable& __h = _M_conjure_hashtable();
847 __node_gen_type __node_gen(__h);
848 return __h._M_insert(__v, __node_gen, __unique_keys{});
849 }
850
851 iterator
852 insert(const_iterator __hint, const value_type& __v)
853 {
854 __hashtable& __h = _M_conjure_hashtable();
855 __node_gen_type __node_gen(__h);
856 return __h._M_insert(__hint, __v, __node_gen, __unique_keys{});
857 }
858
859 template<typename _KType, typename... _Args>
861 try_emplace(const_iterator, _KType&& __k, _Args&&... __args)
862 {
863 __hashtable& __h = _M_conjure_hashtable();
864 auto __code = __h._M_hash_code(__k);
865 std::size_t __bkt = __h._M_bucket_index(__code);
866 if (auto __node = __h._M_find_node(__bkt, __k, __code))
867 return { iterator(__node), false };
868
869 typename __hashtable::_Scoped_node __node {
870 &__h,
874 };
875 auto __it
876 = __h._M_insert_unique_node(__bkt, __code, __node._M_node);
877 __node._M_node = nullptr;
878 return { __it, true };
879 }
880
881 void
882 insert(initializer_list<value_type> __l)
883 { this->insert(__l.begin(), __l.end()); }
884
885 template<typename _InputIterator>
886 void
887 insert(_InputIterator __first, _InputIterator __last)
888 {
889 __hashtable& __h = _M_conjure_hashtable();
890 __node_gen_type __node_gen(__h);
891 return _M_insert_range(__first, __last, __node_gen, __unique_keys{});
892 }
893 };
894
895 template<typename _Key, typename _Value, typename _Alloc,
896 typename _ExtractKey, typename _Equal,
897 typename _Hash, typename _RangeHash, typename _Unused,
898 typename _RehashPolicy, typename _Traits>
899 template<typename _InputIterator, typename _NodeGetter>
900 void
901 _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
902 _Hash, _RangeHash, _Unused,
903 _RehashPolicy, _Traits>::
904 _M_insert_range(_InputIterator __first, _InputIterator __last,
905 const _NodeGetter& __node_gen, true_type __uks)
906 {
907 __hashtable& __h = _M_conjure_hashtable();
908 for (; __first != __last; ++__first)
909 __h._M_insert(*__first, __node_gen, __uks);
910 }
911
912 template<typename _Key, typename _Value, typename _Alloc,
913 typename _ExtractKey, typename _Equal,
914 typename _Hash, typename _RangeHash, typename _Unused,
915 typename _RehashPolicy, typename _Traits>
916 template<typename _InputIterator, typename _NodeGetter>
917 void
918 _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
919 _Hash, _RangeHash, _Unused,
920 _RehashPolicy, _Traits>::
921 _M_insert_range(_InputIterator __first, _InputIterator __last,
922 const _NodeGetter& __node_gen, false_type __uks)
923 {
924 using __rehash_type = typename __hashtable::__rehash_type;
925 using __rehash_state = typename __hashtable::__rehash_state;
926 using pair_type = std::pair<bool, std::size_t>;
927
928 size_type __n_elt = __detail::__distance_fw(__first, __last);
929 if (__n_elt == 0)
930 return;
931
932 __hashtable& __h = _M_conjure_hashtable();
933 __rehash_type& __rehash = __h._M_rehash_policy;
934 const __rehash_state& __saved_state = __rehash._M_state();
935 pair_type __do_rehash = __rehash._M_need_rehash(__h._M_bucket_count,
936 __h._M_element_count,
937 __n_elt);
938
939 if (__do_rehash.first)
940 __h._M_rehash(__do_rehash.second, __saved_state);
941
942 for (; __first != __last; ++__first)
943 __h._M_insert(*__first, __node_gen, __uks);
944 }
945
946 /**
947 * Primary class template _Insert.
948 *
949 * Defines @c insert member functions that depend on _Hashtable policies,
950 * via partial specializations.
951 */
952 template<typename _Key, typename _Value, typename _Alloc,
953 typename _ExtractKey, typename _Equal,
954 typename _Hash, typename _RangeHash, typename _Unused,
955 typename _RehashPolicy, typename _Traits,
956 bool _Constant_iterators = _Traits::__constant_iterators::value>
957 struct _Insert;
958
959 /// Specialization.
960 template<typename _Key, typename _Value, typename _Alloc,
961 typename _ExtractKey, typename _Equal,
962 typename _Hash, typename _RangeHash, typename _Unused,
963 typename _RehashPolicy, typename _Traits>
964 struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
965 _Hash, _RangeHash, _Unused,
966 _RehashPolicy, _Traits, true>
967 : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
968 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>
969 {
970 using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
971 _Equal, _Hash, _RangeHash, _Unused,
972 _RehashPolicy, _Traits>;
973
974 using value_type = typename __base_type::value_type;
975 using iterator = typename __base_type::iterator;
976 using const_iterator = typename __base_type::const_iterator;
977 using __ireturn_type = typename __base_type::__ireturn_type;
978
979 using __unique_keys = typename __base_type::__unique_keys;
980 using __hashtable = typename __base_type::__hashtable;
981 using __node_gen_type = typename __base_type::__node_gen_type;
982
983 using __base_type::insert;
984
985 __ireturn_type
986 insert(value_type&& __v)
987 {
988 __hashtable& __h = this->_M_conjure_hashtable();
989 __node_gen_type __node_gen(__h);
990 return __h._M_insert(std::move(__v), __node_gen, __unique_keys{});
991 }
992
993 iterator
994 insert(const_iterator __hint, value_type&& __v)
995 {
996 __hashtable& __h = this->_M_conjure_hashtable();
997 __node_gen_type __node_gen(__h);
998 return __h._M_insert(__hint, std::move(__v), __node_gen,
999 __unique_keys{});
1000 }
1001 };
1002
1003 /// Specialization.
1004 template<typename _Key, typename _Value, typename _Alloc,
1005 typename _ExtractKey, typename _Equal,
1006 typename _Hash, typename _RangeHash, typename _Unused,
1007 typename _RehashPolicy, typename _Traits>
1008 struct _Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1009 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
1010 : public _Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1011 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>
1012 {
1013 using __base_type = _Insert_base<_Key, _Value, _Alloc, _ExtractKey,
1014 _Equal, _Hash, _RangeHash, _Unused,
1015 _RehashPolicy, _Traits>;
1016 using value_type = typename __base_type::value_type;
1017 using iterator = typename __base_type::iterator;
1018 using const_iterator = typename __base_type::const_iterator;
1019
1020 using __unique_keys = typename __base_type::__unique_keys;
1021 using __hashtable = typename __base_type::__hashtable;
1022 using __ireturn_type = typename __base_type::__ireturn_type;
1023
1024 using __base_type::insert;
1025
1026 template<typename _Pair>
1028
1029 template<typename _Pair>
1031
1032 template<typename _Pair>
1033 using _IFconsp = typename _IFcons<_Pair>::type;
1034
1035 template<typename _Pair, typename = _IFconsp<_Pair>>
1036 __ireturn_type
1037 insert(_Pair&& __v)
1038 {
1039 __hashtable& __h = this->_M_conjure_hashtable();
1040 return __h._M_emplace(__unique_keys{}, std::forward<_Pair>(__v));
1041 }
1042
1043 template<typename _Pair, typename = _IFconsp<_Pair>>
1044 iterator
1045 insert(const_iterator __hint, _Pair&& __v)
1046 {
1047 __hashtable& __h = this->_M_conjure_hashtable();
1048 return __h._M_emplace(__hint, __unique_keys{},
1049 std::forward<_Pair>(__v));
1050 }
1051 };
1052
1053 template<typename _Policy>
1054 using __has_load_factor = typename _Policy::__has_load_factor;
1055
1056 /**
1057 * Primary class template _Rehash_base.
1058 *
1059 * Give hashtable the max_load_factor functions and reserve iff the
1060 * rehash policy supports it.
1061 */
1062 template<typename _Key, typename _Value, typename _Alloc,
1063 typename _ExtractKey, typename _Equal,
1064 typename _Hash, typename _RangeHash, typename _Unused,
1065 typename _RehashPolicy, typename _Traits,
1066 typename =
1067 __detected_or_t<false_type, __has_load_factor, _RehashPolicy>>
1068 struct _Rehash_base;
1069
1070 /// Specialization when rehash policy doesn't provide load factor management.
1071 template<typename _Key, typename _Value, typename _Alloc,
1072 typename _ExtractKey, typename _Equal,
1073 typename _Hash, typename _RangeHash, typename _Unused,
1074 typename _RehashPolicy, typename _Traits>
1075 struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1076 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
1077 false_type /* Has load factor */>
1078 {
1079 };
1080
1081 /// Specialization when rehash policy provide load factor management.
1082 template<typename _Key, typename _Value, typename _Alloc,
1083 typename _ExtractKey, typename _Equal,
1084 typename _Hash, typename _RangeHash, typename _Unused,
1085 typename _RehashPolicy, typename _Traits>
1086 struct _Rehash_base<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1087 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits,
1088 true_type /* Has load factor */>
1089 {
1090 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey,
1091 _Equal, _Hash, _RangeHash, _Unused,
1092 _RehashPolicy, _Traits>;
1093
1094 float
1095 max_load_factor() const noexcept
1096 {
1097 const __hashtable* __this = static_cast<const __hashtable*>(this);
1098 return __this->__rehash_policy().max_load_factor();
1099 }
1100
1101 void
1102 max_load_factor(float __z)
1103 {
1104 __hashtable* __this = static_cast<__hashtable*>(this);
1105 __this->__rehash_policy(_RehashPolicy(__z));
1106 }
1107
1108 void
1109 reserve(std::size_t __n)
1110 {
1111 __hashtable* __this = static_cast<__hashtable*>(this);
1112 __this->rehash(__this->__rehash_policy()._M_bkt_for_elements(__n));
1113 }
1114 };
1115
1116 /**
1117 * Primary class template _Hashtable_ebo_helper.
1118 *
1119 * Helper class using EBO when it is not forbidden (the type is not
1120 * final) and when it is worth it (the type is empty.)
1121 */
1122 template<int _Nm, typename _Tp,
1123 bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
1124 struct _Hashtable_ebo_helper;
1125
1126 /// Specialization using EBO.
1127 template<int _Nm, typename _Tp>
1128 struct _Hashtable_ebo_helper<_Nm, _Tp, true>
1129 : private _Tp
1130 {
1131 _Hashtable_ebo_helper() noexcept(noexcept(_Tp())) : _Tp() { }
1132
1133 template<typename _OtherTp>
1134 _Hashtable_ebo_helper(_OtherTp&& __tp)
1135 : _Tp(std::forward<_OtherTp>(__tp))
1136 { }
1137
1138 const _Tp& _M_cget() const { return static_cast<const _Tp&>(*this); }
1139 _Tp& _M_get() { return static_cast<_Tp&>(*this); }
1140 };
1141
1142 /// Specialization not using EBO.
1143 template<int _Nm, typename _Tp>
1144 struct _Hashtable_ebo_helper<_Nm, _Tp, false>
1145 {
1146 _Hashtable_ebo_helper() = default;
1147
1148 template<typename _OtherTp>
1149 _Hashtable_ebo_helper(_OtherTp&& __tp)
1150 : _M_tp(std::forward<_OtherTp>(__tp))
1151 { }
1152
1153 const _Tp& _M_cget() const { return _M_tp; }
1154 _Tp& _M_get() { return _M_tp; }
1155
1156 private:
1157 _Tp _M_tp{};
1158 };
1159
1160 /**
1161 * Primary class template _Local_iterator_base.
1162 *
1163 * Base class for local iterators, used to iterate within a bucket
1164 * but not between buckets.
1165 */
1166 template<typename _Key, typename _Value, typename _ExtractKey,
1167 typename _Hash, typename _RangeHash, typename _Unused,
1168 bool __cache_hash_code>
1169 struct _Local_iterator_base;
1170
1171 /**
1172 * Primary class template _Hash_code_base.
1173 *
1174 * Encapsulates two policy issues that aren't quite orthogonal.
1175 * (1) the difference between using a ranged hash function and using
1176 * the combination of a hash function and a range-hashing function.
1177 * In the former case we don't have such things as hash codes, so
1178 * we have a dummy type as placeholder.
1179 * (2) Whether or not we cache hash codes. Caching hash codes is
1180 * meaningless if we have a ranged hash function.
1181 *
1182 * We also put the key extraction objects here, for convenience.
1183 * Each specialization derives from one or more of the template
1184 * parameters to benefit from Ebo. This is important as this type
1185 * is inherited in some cases by the _Local_iterator_base type used
1186 * to implement local_iterator and const_local_iterator. As with
1187 * any iterator type we prefer to make it as small as possible.
1188 */
1189 template<typename _Key, typename _Value, typename _ExtractKey,
1190 typename _Hash, typename _RangeHash, typename _Unused,
1191 bool __cache_hash_code>
1192 struct _Hash_code_base
1193 : private _Hashtable_ebo_helper<1, _Hash>
1194 {
1195 private:
1196 using __ebo_hash = _Hashtable_ebo_helper<1, _Hash>;
1197
1198 // Gives the local iterator implementation access to _M_bucket_index().
1199 friend struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1200 _Hash, _RangeHash, _Unused, false>;
1201
1202 public:
1203 typedef _Hash hasher;
1204
1205 hasher
1206 hash_function() const
1207 { return _M_hash(); }
1208
1209 protected:
1210 typedef std::size_t __hash_code;
1211
1212 // We need the default constructor for the local iterators and _Hashtable
1213 // default constructor.
1214 _Hash_code_base() = default;
1215
1216 _Hash_code_base(const _Hash& __hash) : __ebo_hash(__hash) { }
1217
1218 __hash_code
1219 _M_hash_code(const _Key& __k) const
1220 {
1221 static_assert(__is_invocable<const _Hash&, const _Key&>{},
1222 "hash function must be invocable with an argument of key type");
1223 return _M_hash()(__k);
1224 }
1225
1226 template<typename _Kt>
1227 __hash_code
1228 _M_hash_code_tr(const _Kt& __k) const
1229 {
1230 static_assert(__is_invocable<const _Hash&, const _Kt&>{},
1231 "hash function must be invocable with an argument of key type");
1232 return _M_hash()(__k);
1233 }
1234
1235 std::size_t
1236 _M_bucket_index(__hash_code __c, std::size_t __bkt_count) const
1237 { return _RangeHash{}(__c, __bkt_count); }
1238
1239 std::size_t
1240 _M_bucket_index(const _Hash_node_value<_Value, false>& __n,
1241 std::size_t __bkt_count) const
1242 noexcept( noexcept(declval<const _Hash&>()(declval<const _Key&>()))
1243 && noexcept(declval<const _RangeHash&>()((__hash_code)0,
1244 (std::size_t)0)) )
1245 {
1246 return _RangeHash{}(_M_hash_code(_ExtractKey{}(__n._M_v())),
1247 __bkt_count);
1248 }
1249
1250 std::size_t
1251 _M_bucket_index(const _Hash_node_value<_Value, true>& __n,
1252 std::size_t __bkt_count) const
1253 noexcept( noexcept(declval<const _RangeHash&>()((__hash_code)0,
1254 (std::size_t)0)) )
1255 { return _RangeHash{}(__n._M_hash_code, __bkt_count); }
1256
1257 void
1258 _M_store_code(_Hash_node_code_cache<false>&, __hash_code) const
1259 { }
1260
1261 void
1262 _M_copy_code(_Hash_node_code_cache<false>&,
1263 const _Hash_node_code_cache<false>&) const
1264 { }
1265
1266 void
1267 _M_store_code(_Hash_node_code_cache<true>& __n, __hash_code __c) const
1268 { __n._M_hash_code = __c; }
1269
1270 void
1271 _M_copy_code(_Hash_node_code_cache<true>& __to,
1272 const _Hash_node_code_cache<true>& __from) const
1273 { __to._M_hash_code = __from._M_hash_code; }
1274
1275 void
1276 _M_swap(_Hash_code_base& __x)
1277 { std::swap(__ebo_hash::_M_get(), __x.__ebo_hash::_M_get()); }
1278
1279 const _Hash&
1280 _M_hash() const { return __ebo_hash::_M_cget(); }
1281 };
1282
1283 /// Partial specialization used when nodes contain a cached hash code.
1284 template<typename _Key, typename _Value, typename _ExtractKey,
1285 typename _Hash, typename _RangeHash, typename _Unused>
1286 struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1287 _Hash, _RangeHash, _Unused, true>
1288 : public _Node_iterator_base<_Value, true>
1289 {
1290 protected:
1291 using __base_node_iter = _Node_iterator_base<_Value, true>;
1292 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1293 _Hash, _RangeHash, _Unused, true>;
1294
1295 _Local_iterator_base() = default;
1296 _Local_iterator_base(const __hash_code_base&,
1297 _Hash_node<_Value, true>* __p,
1298 std::size_t __bkt, std::size_t __bkt_count)
1299 : __base_node_iter(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1300 { }
1301
1302 void
1303 _M_incr()
1304 {
1305 __base_node_iter::_M_incr();
1306 if (this->_M_cur)
1307 {
1308 std::size_t __bkt
1309 = _RangeHash{}(this->_M_cur->_M_hash_code, _M_bucket_count);
1310 if (__bkt != _M_bucket)
1311 this->_M_cur = nullptr;
1312 }
1313 }
1314
1315 std::size_t _M_bucket;
1316 std::size_t _M_bucket_count;
1317
1318 public:
1319 std::size_t
1320 _M_get_bucket() const { return _M_bucket; } // for debug mode
1321 };
1322
1323 // Uninitialized storage for a _Hash_code_base.
1324 // This type is DefaultConstructible and Assignable even if the
1325 // _Hash_code_base type isn't, so that _Local_iterator_base<..., false>
1326 // can be DefaultConstructible and Assignable.
1327 template<typename _Tp, bool _IsEmpty = std::is_empty<_Tp>::value>
1328 struct _Hash_code_storage
1329 {
1330 __gnu_cxx::__aligned_buffer<_Tp> _M_storage;
1331
1332 _Tp*
1333 _M_h() { return _M_storage._M_ptr(); }
1334
1335 const _Tp*
1336 _M_h() const { return _M_storage._M_ptr(); }
1337 };
1338
1339 // Empty partial specialization for empty _Hash_code_base types.
1340 template<typename _Tp>
1341 struct _Hash_code_storage<_Tp, true>
1342 {
1343 static_assert( std::is_empty<_Tp>::value, "Type must be empty" );
1344
1345 // As _Tp is an empty type there will be no bytes written/read through
1346 // the cast pointer, so no strict-aliasing violation.
1347 _Tp*
1348 _M_h() { return reinterpret_cast<_Tp*>(this); }
1349
1350 const _Tp*
1351 _M_h() const { return reinterpret_cast<const _Tp*>(this); }
1352 };
1353
1354 template<typename _Key, typename _Value, typename _ExtractKey,
1355 typename _Hash, typename _RangeHash, typename _Unused>
1356 using __hash_code_for_local_iter
1357 = _Hash_code_storage<_Hash_code_base<_Key, _Value, _ExtractKey,
1358 _Hash, _RangeHash, _Unused, false>>;
1359
1360 // Partial specialization used when hash codes are not cached
1361 template<typename _Key, typename _Value, typename _ExtractKey,
1362 typename _Hash, typename _RangeHash, typename _Unused>
1363 struct _Local_iterator_base<_Key, _Value, _ExtractKey,
1364 _Hash, _RangeHash, _Unused, false>
1365 : __hash_code_for_local_iter<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1366 _Unused>
1367 , _Node_iterator_base<_Value, false>
1368 {
1369 protected:
1370 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1371 _Hash, _RangeHash, _Unused, false>;
1372 using __node_iter_base = _Node_iterator_base<_Value, false>;
1373
1374 _Local_iterator_base() : _M_bucket_count(-1) { }
1375
1376 _Local_iterator_base(const __hash_code_base& __base,
1377 _Hash_node<_Value, false>* __p,
1378 std::size_t __bkt, std::size_t __bkt_count)
1379 : __node_iter_base(__p), _M_bucket(__bkt), _M_bucket_count(__bkt_count)
1380 { _M_init(__base); }
1381
1382 ~_Local_iterator_base()
1383 {
1384 if (_M_bucket_count != size_t(-1))
1385 _M_destroy();
1386 }
1387
1388 _Local_iterator_base(const _Local_iterator_base& __iter)
1389 : __node_iter_base(__iter._M_cur), _M_bucket(__iter._M_bucket)
1390 , _M_bucket_count(__iter._M_bucket_count)
1391 {
1392 if (_M_bucket_count != size_t(-1))
1393 _M_init(*__iter._M_h());
1394 }
1395
1396 _Local_iterator_base&
1397 operator=(const _Local_iterator_base& __iter)
1398 {
1399 if (_M_bucket_count != -1)
1400 _M_destroy();
1401 this->_M_cur = __iter._M_cur;
1402 _M_bucket = __iter._M_bucket;
1403 _M_bucket_count = __iter._M_bucket_count;
1404 if (_M_bucket_count != -1)
1405 _M_init(*__iter._M_h());
1406 return *this;
1407 }
1408
1409 void
1410 _M_incr()
1411 {
1412 __node_iter_base::_M_incr();
1413 if (this->_M_cur)
1414 {
1415 std::size_t __bkt = this->_M_h()->_M_bucket_index(*this->_M_cur,
1416 _M_bucket_count);
1417 if (__bkt != _M_bucket)
1418 this->_M_cur = nullptr;
1419 }
1420 }
1421
1422 std::size_t _M_bucket;
1423 std::size_t _M_bucket_count;
1424
1425 void
1426 _M_init(const __hash_code_base& __base)
1427 { ::new(this->_M_h()) __hash_code_base(__base); }
1428
1429 void
1430 _M_destroy() { this->_M_h()->~__hash_code_base(); }
1431
1432 public:
1433 std::size_t
1434 _M_get_bucket() const { return _M_bucket; } // for debug mode
1435 };
1436
1437 /// local iterators
1438 template<typename _Key, typename _Value, typename _ExtractKey,
1439 typename _Hash, typename _RangeHash, typename _Unused,
1440 bool __constant_iterators, bool __cache>
1441 struct _Local_iterator
1442 : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1443 _Hash, _RangeHash, _Unused, __cache>
1444 {
1445 private:
1446 using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1447 _Hash, _RangeHash, _Unused, __cache>;
1448 using __hash_code_base = typename __base_type::__hash_code_base;
1449
1450 public:
1451 typedef _Value value_type;
1452 typedef typename std::conditional<__constant_iterators,
1453 const value_type*, value_type*>::type
1454 pointer;
1455 typedef typename std::conditional<__constant_iterators,
1456 const value_type&, value_type&>::type
1457 reference;
1458 typedef std::ptrdiff_t difference_type;
1459 typedef std::forward_iterator_tag iterator_category;
1460
1461 _Local_iterator() = default;
1462
1463 _Local_iterator(const __hash_code_base& __base,
1464 _Hash_node<_Value, __cache>* __n,
1465 std::size_t __bkt, std::size_t __bkt_count)
1466 : __base_type(__base, __n, __bkt, __bkt_count)
1467 { }
1468
1469 reference
1470 operator*() const
1471 { return this->_M_cur->_M_v(); }
1472
1473 pointer
1474 operator->() const
1475 { return this->_M_cur->_M_valptr(); }
1476
1477 _Local_iterator&
1478 operator++()
1479 {
1480 this->_M_incr();
1481 return *this;
1482 }
1483
1484 _Local_iterator
1485 operator++(int)
1486 {
1487 _Local_iterator __tmp(*this);
1488 this->_M_incr();
1489 return __tmp;
1490 }
1491 };
1492
1493 /// local const_iterators
1494 template<typename _Key, typename _Value, typename _ExtractKey,
1495 typename _Hash, typename _RangeHash, typename _Unused,
1496 bool __constant_iterators, bool __cache>
1497 struct _Local_const_iterator
1498 : public _Local_iterator_base<_Key, _Value, _ExtractKey,
1499 _Hash, _RangeHash, _Unused, __cache>
1500 {
1501 private:
1502 using __base_type = _Local_iterator_base<_Key, _Value, _ExtractKey,
1503 _Hash, _RangeHash, _Unused, __cache>;
1504 using __hash_code_base = typename __base_type::__hash_code_base;
1505
1506 public:
1507 typedef _Value value_type;
1508 typedef const value_type* pointer;
1509 typedef const value_type& reference;
1510 typedef std::ptrdiff_t difference_type;
1511 typedef std::forward_iterator_tag iterator_category;
1512
1513 _Local_const_iterator() = default;
1514
1515 _Local_const_iterator(const __hash_code_base& __base,
1516 _Hash_node<_Value, __cache>* __n,
1517 std::size_t __bkt, std::size_t __bkt_count)
1518 : __base_type(__base, __n, __bkt, __bkt_count)
1519 { }
1520
1521 _Local_const_iterator(const _Local_iterator<_Key, _Value, _ExtractKey,
1522 _Hash, _RangeHash, _Unused,
1523 __constant_iterators,
1524 __cache>& __x)
1525 : __base_type(__x)
1526 { }
1527
1528 reference
1529 operator*() const
1530 { return this->_M_cur->_M_v(); }
1531
1532 pointer
1533 operator->() const
1534 { return this->_M_cur->_M_valptr(); }
1535
1536 _Local_const_iterator&
1537 operator++()
1538 {
1539 this->_M_incr();
1540 return *this;
1541 }
1542
1543 _Local_const_iterator
1544 operator++(int)
1545 {
1546 _Local_const_iterator __tmp(*this);
1547 this->_M_incr();
1548 return __tmp;
1549 }
1550 };
1551
1552 /**
1553 * Primary class template _Hashtable_base.
1554 *
1555 * Helper class adding management of _Equal functor to
1556 * _Hash_code_base type.
1557 *
1558 * Base class templates are:
1559 * - __detail::_Hash_code_base
1560 * - __detail::_Hashtable_ebo_helper
1561 */
1562 template<typename _Key, typename _Value, typename _ExtractKey,
1563 typename _Equal, typename _Hash, typename _RangeHash,
1564 typename _Unused, typename _Traits>
1565 struct _Hashtable_base
1566 : public _Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash,
1567 _Unused, _Traits::__hash_cached::value>,
1568 private _Hashtable_ebo_helper<0, _Equal>
1569 {
1570 public:
1571 typedef _Key key_type;
1572 typedef _Value value_type;
1573 typedef _Equal key_equal;
1574 typedef std::size_t size_type;
1575 typedef std::ptrdiff_t difference_type;
1576
1577 using __traits_type = _Traits;
1578 using __hash_cached = typename __traits_type::__hash_cached;
1579
1580 using __hash_code_base = _Hash_code_base<_Key, _Value, _ExtractKey,
1581 _Hash, _RangeHash, _Unused,
1582 __hash_cached::value>;
1583
1584 using __hash_code = typename __hash_code_base::__hash_code;
1585
1586 private:
1587 using _EqualEBO = _Hashtable_ebo_helper<0, _Equal>;
1588
1589 static bool
1590 _S_equals(__hash_code, const _Hash_node_code_cache<false>&)
1591 { return true; }
1592
1593 static bool
1594 _S_node_equals(const _Hash_node_code_cache<false>&,
1595 const _Hash_node_code_cache<false>&)
1596 { return true; }
1597
1598 static bool
1599 _S_equals(__hash_code __c, const _Hash_node_code_cache<true>& __n)
1600 { return __c == __n._M_hash_code; }
1601
1602 static bool
1603 _S_node_equals(const _Hash_node_code_cache<true>& __lhn,
1604 const _Hash_node_code_cache<true>& __rhn)
1605 { return __lhn._M_hash_code == __rhn._M_hash_code; }
1606
1607 protected:
1608 _Hashtable_base() = default;
1609
1610 _Hashtable_base(const _Hash& __hash, const _Equal& __eq)
1611 : __hash_code_base(__hash), _EqualEBO(__eq)
1612 { }
1613
1614 bool
1615 _M_equals(const _Key& __k, __hash_code __c,
1616 const _Hash_node_value<_Value, __hash_cached::value>& __n) const
1617 {
1618 static_assert(__is_invocable<const _Equal&, const _Key&, const _Key&>{},
1619 "key equality predicate must be invocable with two arguments of "
1620 "key type");
1621 return _S_equals(__c, __n) && _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1622 }
1623
1624 template<typename _Kt>
1625 bool
1626 _M_equals_tr(const _Kt& __k, __hash_code __c,
1627 const _Hash_node_value<_Value,
1628 __hash_cached::value>& __n) const
1629 {
1630 static_assert(
1631 __is_invocable<const _Equal&, const _Kt&, const _Key&>{},
1632 "key equality predicate must be invocable with two arguments of "
1633 "key type");
1634 return _S_equals(__c, __n) && _M_eq()(__k, _ExtractKey{}(__n._M_v()));
1635 }
1636
1637 bool
1638 _M_node_equals(
1639 const _Hash_node_value<_Value, __hash_cached::value>& __lhn,
1640 const _Hash_node_value<_Value, __hash_cached::value>& __rhn) const
1641 {
1642 return _S_node_equals(__lhn, __rhn)
1643 && _M_eq()(_ExtractKey{}(__lhn._M_v()), _ExtractKey{}(__rhn._M_v()));
1644 }
1645
1646 void
1647 _M_swap(_Hashtable_base& __x)
1648 {
1649 __hash_code_base::_M_swap(__x);
1650 std::swap(_EqualEBO::_M_get(), __x._EqualEBO::_M_get());
1651 }
1652
1653 const _Equal&
1654 _M_eq() const { return _EqualEBO::_M_cget(); }
1655 };
1656
1657 /**
1658 * Primary class template _Equality.
1659 *
1660 * This is for implementing equality comparison for unordered
1661 * containers, per N3068, by John Lakos and Pablo Halpern.
1662 * Algorithmically, we follow closely the reference implementations
1663 * therein.
1664 */
1665 template<typename _Key, typename _Value, typename _Alloc,
1666 typename _ExtractKey, typename _Equal,
1667 typename _Hash, typename _RangeHash, typename _Unused,
1668 typename _RehashPolicy, typename _Traits,
1669 bool _Unique_keys = _Traits::__unique_keys::value>
1670 struct _Equality;
1671
1672 /// unordered_map and unordered_set specializations.
1673 template<typename _Key, typename _Value, typename _Alloc,
1674 typename _ExtractKey, typename _Equal,
1675 typename _Hash, typename _RangeHash, typename _Unused,
1676 typename _RehashPolicy, typename _Traits>
1677 struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1678 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>
1679 {
1680 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1681 _Hash, _RangeHash, _Unused,
1682 _RehashPolicy, _Traits>;
1683
1684 bool
1685 _M_equal(const __hashtable&) const;
1686 };
1687
1688 template<typename _Key, typename _Value, typename _Alloc,
1689 typename _ExtractKey, typename _Equal,
1690 typename _Hash, typename _RangeHash, typename _Unused,
1691 typename _RehashPolicy, typename _Traits>
1692 bool
1693 _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1694 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>::
1695 _M_equal(const __hashtable& __other) const
1696 {
1697 using __node_type = typename __hashtable::__node_type;
1698 const __hashtable* __this = static_cast<const __hashtable*>(this);
1699 if (__this->size() != __other.size())
1700 return false;
1701
1702 for (auto __itx = __this->begin(); __itx != __this->end(); ++__itx)
1703 {
1704 std::size_t __ybkt = __other._M_bucket_index(*__itx._M_cur);
1705 auto __prev_n = __other._M_buckets[__ybkt];
1706 if (!__prev_n)
1707 return false;
1708
1709 for (__node_type* __n = static_cast<__node_type*>(__prev_n->_M_nxt);;
1710 __n = __n->_M_next())
1711 {
1712 if (__n->_M_v() == *__itx)
1713 break;
1714
1715 if (!__n->_M_nxt
1716 || __other._M_bucket_index(*__n->_M_next()) != __ybkt)
1717 return false;
1718 }
1719 }
1720
1721 return true;
1722 }
1723
1724 /// unordered_multiset and unordered_multimap specializations.
1725 template<typename _Key, typename _Value, typename _Alloc,
1726 typename _ExtractKey, typename _Equal,
1727 typename _Hash, typename _RangeHash, typename _Unused,
1728 typename _RehashPolicy, typename _Traits>
1729 struct _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1730 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>
1731 {
1732 using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1733 _Hash, _RangeHash, _Unused,
1734 _RehashPolicy, _Traits>;
1735
1736 bool
1737 _M_equal(const __hashtable&) const;
1738 };
1739
1740 template<typename _Key, typename _Value, typename _Alloc,
1741 typename _ExtractKey, typename _Equal,
1742 typename _Hash, typename _RangeHash, typename _Unused,
1743 typename _RehashPolicy, typename _Traits>
1744 bool
1745 _Equality<_Key, _Value, _Alloc, _ExtractKey, _Equal,
1746 _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false>::
1747 _M_equal(const __hashtable& __other) const
1748 {
1749 using __node_type = typename __hashtable::__node_type;
1750 const __hashtable* __this = static_cast<const __hashtable*>(this);
1751 if (__this->size() != __other.size())
1752 return false;
1753
1754 for (auto __itx = __this->begin(); __itx != __this->end();)
1755 {
1756 std::size_t __x_count = 1;
1757 auto __itx_end = __itx;
1758 for (++__itx_end; __itx_end != __this->end()
1759 && __this->key_eq()(_ExtractKey{}(*__itx),
1760 _ExtractKey{}(*__itx_end));
1761 ++__itx_end)
1762 ++__x_count;
1763
1764 std::size_t __ybkt = __other._M_bucket_index(*__itx._M_cur);
1765 auto __y_prev_n = __other._M_buckets[__ybkt];
1766 if (!__y_prev_n)
1767 return false;
1768
1769 __node_type* __y_n = static_cast<__node_type*>(__y_prev_n->_M_nxt);
1770 for (;;)
1771 {
1772 if (__this->key_eq()(_ExtractKey{}(__y_n->_M_v()),
1773 _ExtractKey{}(*__itx)))
1774 break;
1775
1776 auto __y_ref_n = __y_n;
1777 for (__y_n = __y_n->_M_next(); __y_n; __y_n = __y_n->_M_next())
1778 if (!__other._M_node_equals(*__y_ref_n, *__y_n))
1779 break;
1780
1781 if (!__y_n || __other._M_bucket_index(*__y_n) != __ybkt)
1782 return false;
1783 }
1784
1785 typename __hashtable::const_iterator __ity(__y_n);
1786 for (auto __ity_end = __ity; __ity_end != __other.end(); ++__ity_end)
1787 if (--__x_count == 0)
1788 break;
1789
1790 if (__x_count != 0)
1791 return false;
1792
1793 if (!std::is_permutation(__itx, __itx_end, __ity))
1794 return false;
1795
1796 __itx = __itx_end;
1797 }
1798 return true;
1799 }
1800
1801 /**
1802 * This type deals with all allocation and keeps an allocator instance
1803 * through inheritance to benefit from EBO when possible.
1804 */
1805 template<typename _NodeAlloc>
1806 struct _Hashtable_alloc : private _Hashtable_ebo_helper<0, _NodeAlloc>
1807 {
1808 private:
1809 using __ebo_node_alloc = _Hashtable_ebo_helper<0, _NodeAlloc>;
1810 public:
1811 using __node_type = typename _NodeAlloc::value_type;
1812 using __node_alloc_type = _NodeAlloc;
1813 // Use __gnu_cxx to benefit from _S_always_equal and al.
1814 using __node_alloc_traits = __gnu_cxx::__alloc_traits<__node_alloc_type>;
1815
1816 using __value_alloc_traits = typename __node_alloc_traits::template
1817 rebind_traits<typename __node_type::value_type>;
1818
1819 using __node_ptr = __node_type*;
1820 using __node_base = _Hash_node_base;
1821 using __node_base_ptr = __node_base*;
1822 using __buckets_alloc_type =
1823 __alloc_rebind<__node_alloc_type, __node_base_ptr>;
1824 using __buckets_alloc_traits = std::allocator_traits<__buckets_alloc_type>;
1825 using __buckets_ptr = __node_base_ptr*;
1826
1827 _Hashtable_alloc() = default;
1828 _Hashtable_alloc(const _Hashtable_alloc&) = default;
1829 _Hashtable_alloc(_Hashtable_alloc&&) = default;
1830
1831 template<typename _Alloc>
1832 _Hashtable_alloc(_Alloc&& __a)
1833 : __ebo_node_alloc(std::forward<_Alloc>(__a))
1834 { }
1835
1836 __node_alloc_type&
1837 _M_node_allocator()
1838 { return __ebo_node_alloc::_M_get(); }
1839
1840 const __node_alloc_type&
1841 _M_node_allocator() const
1842 { return __ebo_node_alloc::_M_cget(); }
1843
1844 // Allocate a node and construct an element within it.
1845 template<typename... _Args>
1846 __node_ptr
1847 _M_allocate_node(_Args&&... __args);
1848
1849 // Destroy the element within a node and deallocate the node.
1850 void
1851 _M_deallocate_node(__node_ptr __n);
1852
1853 // Deallocate a node.
1854 void
1855 _M_deallocate_node_ptr(__node_ptr __n);
1856
1857 // Deallocate the linked list of nodes pointed to by __n.
1858 // The elements within the nodes are destroyed.
1859 void
1860 _M_deallocate_nodes(__node_ptr __n);
1861
1862 __buckets_ptr
1863 _M_allocate_buckets(std::size_t __bkt_count);
1864
1865 void
1866 _M_deallocate_buckets(__buckets_ptr, std::size_t __bkt_count);
1867 };
1868
1869 // Definitions of class template _Hashtable_alloc's out-of-line member
1870 // functions.
1871 template<typename _NodeAlloc>
1872 template<typename... _Args>
1873 auto
1874 _Hashtable_alloc<_NodeAlloc>::_M_allocate_node(_Args&&... __args)
1875 -> __node_ptr
1876 {
1877 auto __nptr = __node_alloc_traits::allocate(_M_node_allocator(), 1);
1878 __node_ptr __n = std::__to_address(__nptr);
1879 __try
1880 {
1881 ::new ((void*)__n) __node_type;
1882 __node_alloc_traits::construct(_M_node_allocator(),
1883 __n->_M_valptr(),
1884 std::forward<_Args>(__args)...);
1885 return __n;
1886 }
1887 __catch(...)
1888 {
1889 __node_alloc_traits::deallocate(_M_node_allocator(), __nptr, 1);
1890 __throw_exception_again;
1891 }
1892 }
1893
1894 template<typename _NodeAlloc>
1895 void
1896 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_ptr __n)
1897 {
1898 __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
1899 _M_deallocate_node_ptr(__n);
1900 }
1901
1902 template<typename _NodeAlloc>
1903 void
1904 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node_ptr(__node_ptr __n)
1905 {
1906 typedef typename __node_alloc_traits::pointer _Ptr;
1907 auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
1908 __n->~__node_type();
1909 __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
1910 }
1911
1912 template<typename _NodeAlloc>
1913 void
1914 _Hashtable_alloc<_NodeAlloc>::_M_deallocate_nodes(__node_ptr __n)
1915 {
1916 while (__n)
1917 {
1918 __node_ptr __tmp = __n;
1919 __n = __n->_M_next();
1920 _M_deallocate_node(__tmp);
1921 }
1922 }
1923
1924 template<typename _NodeAlloc>
1925 auto
1926 _Hashtable_alloc<_NodeAlloc>::_M_allocate_buckets(std::size_t __bkt_count)
1927 -> __buckets_ptr
1928 {
1929 __buckets_alloc_type __alloc(_M_node_allocator());
1930
1931 auto __ptr = __buckets_alloc_traits::allocate(__alloc, __bkt_count);
1932 __buckets_ptr __p = std::__to_address(__ptr);
1933 __builtin_memset(__p, 0, __bkt_count * sizeof(__node_base_ptr));
1934 return __p;
1935 }
1936
1937 template<typename _NodeAlloc>
1938 void
1939 _Hashtable_alloc<_NodeAlloc>::
1940 _M_deallocate_buckets(__buckets_ptr __bkts,
1941 std::size_t __bkt_count)
1942 {
1943 typedef typename __buckets_alloc_traits::pointer _Ptr;
1944 auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__bkts);
1945 __buckets_alloc_type __alloc(_M_node_allocator());
1946 __buckets_alloc_traits::deallocate(__alloc, __ptr, __bkt_count);
1947 }
1948
1949 ///@} hashtable-detail
1950} // namespace __detail
1951/// @endcond
1952_GLIBCXX_END_NAMESPACE_VERSION
1953} // namespace std
1954
1955#endif // _HASHTABLE_POLICY_H
constexpr duration< __common_rep_t< _Rep2, _Rep1 >, _Period > operator*(const _Rep1 &__s, const duration< _Rep2, _Period > &__d)
Definition chrono:700
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition type_traits:83
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
Definition type_traits:86
constexpr tuple< _Elements &&... > forward_as_tuple(_Elements &&... __args) noexcept
std::forward_as_tuple
Definition tuple:1631
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition move.h:104
constexpr piecewise_construct_t piecewise_construct
Tag for piecewise construction of std::pair objects.
Definition stl_pair.h:83
void swap(any &__x, any &__y) noexcept
Exchange the states of two any objects.
Definition any:428
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition move.h:77
constexpr iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
ISO C++ entities toplevel namespace is std.
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
__numeric_traits_integer< _Tp > __int_traits
Convenience alias for __numeric_traits<integer-type>.
constexpr _Iterator __base(_Iterator __it)
tuple_element
Definition array:442
Primary class template, tuple.
Definition tuple:610
Define a member typedef type to one of two argument types.
Definition type_traits:2221
is_empty
Definition type_traits:757
Traits class for iterators.
Uniform interface to all pointer-like types.
Definition ptr_traits.h:101
Marking input iterators.
Forward iterators support a superset of input iterator operations.
Uniform interface to C++98 and C++11 allocators.