1// unordered_map implementation -*- C++ -*-
2
3// Copyright (C) 2010-2018 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/unordered_map.h
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly. @headername{unordered_map}
28 */
29
30#ifndef _UNORDERED_MAP_H
31#define _UNORDERED_MAP_H
32
33namespace std _GLIBCXX_VISIBILITY(default)
34{
35_GLIBCXX_BEGIN_NAMESPACE_VERSION
36_GLIBCXX_BEGIN_NAMESPACE_CONTAINER
37
38 /// Base types for unordered_map.
39 template<bool _Cache>
40 using __umap_traits = __detail::_Hashtable_traits<_Cache, false, true>;
41
42 template<typename _Key,
43 typename _Tp,
44 typename _Hash = hash<_Key>,
45 typename _Pred = std::equal_to<_Key>,
46 typename _Alloc = std::allocator<std::pair<const _Key, _Tp> >,
47 typename _Tr = __umap_traits<__cache_default<_Key, _Hash>::value>>
48 using __umap_hashtable = _Hashtable<_Key, std::pair<const _Key, _Tp>,
49 _Alloc, __detail::_Select1st,
50 _Pred, _Hash,
51 __detail::_Mod_range_hashing,
52 __detail::_Default_ranged_hash,
53 __detail::_Prime_rehash_policy, _Tr>;
54
55 /// Base types for unordered_multimap.
56 template<bool _Cache>
57 using __ummap_traits = __detail::_Hashtable_traits<_Cache, false, false>;
58
59 template<typename _Key,
60 typename _Tp,
61 typename _Hash = hash<_Key>,
62 typename _Pred = std::equal_to<_Key>,
63 typename _Alloc = std::allocator<std::pair<const _Key, _Tp> >,
64 typename _Tr = __ummap_traits<__cache_default<_Key, _Hash>::value>>
65 using __ummap_hashtable = _Hashtable<_Key, std::pair<const _Key, _Tp>,
66 _Alloc, __detail::_Select1st,
67 _Pred, _Hash,
68 __detail::_Mod_range_hashing,
69 __detail::_Default_ranged_hash,
70 __detail::_Prime_rehash_policy, _Tr>;
71
72 template<class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
73 class unordered_multimap;
74
75 /**
76 * @brief A standard container composed of unique keys (containing
77 * at most one of each key value) that associates values of another type
78 * with the keys.
79 *
80 * @ingroup unordered_associative_containers
81 *
82 * @tparam _Key Type of key objects.
83 * @tparam _Tp Type of mapped objects.
84 * @tparam _Hash Hashing function object type, defaults to hash<_Value>.
85 * @tparam _Pred Predicate function object type, defaults
86 * to equal_to<_Value>.
87 * @tparam _Alloc Allocator type, defaults to
88 * std::allocator<std::pair<const _Key, _Tp>>.
89 *
90 * Meets the requirements of a <a href="tables.html#65">container</a>, and
91 * <a href="tables.html#xx">unordered associative container</a>
92 *
93 * The resulting value type of the container is std::pair<const _Key, _Tp>.
94 *
95 * Base is _Hashtable, dispatched at compile time via template
96 * alias __umap_hashtable.
97 */
98 template<typename _Key, typename _Tp,
99 typename _Hash = hash<_Key>,
100 typename _Pred = equal_to<_Key>,
101 typename _Alloc = allocator<std::pair<const _Key, _Tp>>>
102 class unordered_map
103 {
104 typedef __umap_hashtable<_Key, _Tp, _Hash, _Pred, _Alloc> _Hashtable;
105 _Hashtable _M_h;
106
107 public:
108 // typedefs:
109 //@{
110 /// Public typedefs.
111 typedef typename _Hashtable::key_type key_type;
112 typedef typename _Hashtable::value_type value_type;
113 typedef typename _Hashtable::mapped_type mapped_type;
114 typedef typename _Hashtable::hasher hasher;
115 typedef typename _Hashtable::key_equal key_equal;
116 typedef typename _Hashtable::allocator_type allocator_type;
117 //@}
118
119 //@{
120 /// Iterator-related typedefs.
121 typedef typename _Hashtable::pointer pointer;
122 typedef typename _Hashtable::const_pointer const_pointer;
123 typedef typename _Hashtable::reference reference;
124 typedef typename _Hashtable::const_reference const_reference;
125 typedef typename _Hashtable::iterator iterator;
126 typedef typename _Hashtable::const_iterator const_iterator;
127 typedef typename _Hashtable::local_iterator local_iterator;
128 typedef typename _Hashtable::const_local_iterator const_local_iterator;
129 typedef typename _Hashtable::size_type size_type;
130 typedef typename _Hashtable::difference_type difference_type;
131 //@}
132
133#if __cplusplus > 201402L
134 using node_type = typename _Hashtable::node_type;
135 using insert_return_type = typename _Hashtable::insert_return_type;
136#endif
137
138 //construct/destroy/copy
139
140 /// Default constructor.
141 unordered_map() = default;
142
143 /**
144 * @brief Default constructor creates no elements.
145 * @param __n Minimal initial number of buckets.
146 * @param __hf A hash functor.
147 * @param __eql A key equality functor.
148 * @param __a An allocator object.
149 */
150 explicit
151 unordered_map(size_type __n,
152 const hasher& __hf = hasher(),
153 const key_equal& __eql = key_equal(),
154 const allocator_type& __a = allocator_type())
155 : _M_h(__n, __hf, __eql, __a)
156 { }
157
158 /**
159 * @brief Builds an %unordered_map from a range.
160 * @param __first An input iterator.
161 * @param __last An input iterator.
162 * @param __n Minimal initial number of buckets.
163 * @param __hf A hash functor.
164 * @param __eql A key equality functor.
165 * @param __a An allocator object.
166 *
167 * Create an %unordered_map consisting of copies of the elements from
168 * [__first,__last). This is linear in N (where N is
169 * distance(__first,__last)).
170 */
171 template<typename _InputIterator>
172 unordered_map(_InputIterator __first, _InputIterator __last,
173 size_type __n = 0,
174 const hasher& __hf = hasher(),
175 const key_equal& __eql = key_equal(),
176 const allocator_type& __a = allocator_type())
177 : _M_h(__first, __last, __n, __hf, __eql, __a)
178 { }
179
180 /// Copy constructor.
181 unordered_map(const unordered_map&) = default;
182
183 /// Move constructor.
184 unordered_map(unordered_map&&) = default;
185
186 /**
187 * @brief Creates an %unordered_map with no elements.
188 * @param __a An allocator object.
189 */
190 explicit
191 unordered_map(const allocator_type& __a)
192 : _M_h(__a)
193 { }
194
195 /*
196 * @brief Copy constructor with allocator argument.
197 * @param __uset Input %unordered_map to copy.
198 * @param __a An allocator object.
199 */
200 unordered_map(const unordered_map& __umap,
201 const allocator_type& __a)
202 : _M_h(__umap._M_h, __a)
203 { }
204
205 /*
206 * @brief Move constructor with allocator argument.
207 * @param __uset Input %unordered_map to move.
208 * @param __a An allocator object.
209 */
210 unordered_map(unordered_map&& __umap,
211 const allocator_type& __a)
212 : _M_h(std::move(__umap._M_h), __a)
213 { }
214
215 /**
216 * @brief Builds an %unordered_map from an initializer_list.
217 * @param __l An initializer_list.
218 * @param __n Minimal initial number of buckets.
219 * @param __hf A hash functor.
220 * @param __eql A key equality functor.
221 * @param __a An allocator object.
222 *
223 * Create an %unordered_map consisting of copies of the elements in the
224 * list. This is linear in N (where N is @a __l.size()).
225 */
226 unordered_map(initializer_list<value_type> __l,
227 size_type __n = 0,
228 const hasher& __hf = hasher(),
229 const key_equal& __eql = key_equal(),
230 const allocator_type& __a = allocator_type())
231 : _M_h(__l, __n, __hf, __eql, __a)
232 { }
233
234 unordered_map(size_type __n, const allocator_type& __a)
235 : unordered_map(__n, hasher(), key_equal(), __a)
236 { }
237
238 unordered_map(size_type __n, const hasher& __hf,
239 const allocator_type& __a)
240 : unordered_map(__n, __hf, key_equal(), __a)
241 { }
242
243 template<typename _InputIterator>
244 unordered_map(_InputIterator __first, _InputIterator __last,
245 size_type __n,
246 const allocator_type& __a)
247 : unordered_map(__first, __last, __n, hasher(), key_equal(), __a)
248 { }
249
250 template<typename _InputIterator>
251 unordered_map(_InputIterator __first, _InputIterator __last,
252 size_type __n, const hasher& __hf,
253 const allocator_type& __a)
254 : unordered_map(__first, __last, __n, __hf, key_equal(), __a)
255 { }
256
257 unordered_map(initializer_list<value_type> __l,
258 size_type __n,
259 const allocator_type& __a)
260 : unordered_map(__l, __n, hasher(), key_equal(), __a)
261 { }
262
263 unordered_map(initializer_list<value_type> __l,
264 size_type __n, const hasher& __hf,
265 const allocator_type& __a)
266 : unordered_map(__l, __n, __hf, key_equal(), __a)
267 { }
268
269 /// Copy assignment operator.
270 unordered_map&
271 operator=(const unordered_map&) = default;
272
273 /// Move assignment operator.
274 unordered_map&
275 operator=(unordered_map&&) = default;
276
277 /**
278 * @brief %Unordered_map list assignment operator.
279 * @param __l An initializer_list.
280 *
281 * This function fills an %unordered_map with copies of the elements in
282 * the initializer list @a __l.
283 *
284 * Note that the assignment completely changes the %unordered_map and
285 * that the resulting %unordered_map's size is the same as the number
286 * of elements assigned.
287 */
288 unordered_map&
289 operator=(initializer_list<value_type> __l)
290 {
291 _M_h = __l;
292 return *this;
293 }
294
295 /// Returns the allocator object used by the %unordered_map.
296 allocator_type
297 get_allocator() const noexcept
298 { return _M_h.get_allocator(); }
299
300 // size and capacity:
301
302 /// Returns true if the %unordered_map is empty.
303 bool
304 empty() const noexcept
305 { return _M_h.empty(); }
306
307 /// Returns the size of the %unordered_map.
308 size_type
309 size() const noexcept
310 { return _M_h.size(); }
311
312 /// Returns the maximum size of the %unordered_map.
313 size_type
314 max_size() const noexcept
315 { return _M_h.max_size(); }
316
317 // iterators.
318
319 /**
320 * Returns a read/write iterator that points to the first element in the
321 * %unordered_map.
322 */
323 iterator
324 begin() noexcept
325 { return _M_h.begin(); }
326
327 //@{
328 /**
329 * Returns a read-only (constant) iterator that points to the first
330 * element in the %unordered_map.
331 */
332 const_iterator
333 begin() const noexcept
334 { return _M_h.begin(); }
335
336 const_iterator
337 cbegin() const noexcept
338 { return _M_h.begin(); }
339 //@}
340
341 /**
342 * Returns a read/write iterator that points one past the last element in
343 * the %unordered_map.
344 */
345 iterator
346 end() noexcept
347 { return _M_h.end(); }
348
349 //@{
350 /**
351 * Returns a read-only (constant) iterator that points one past the last
352 * element in the %unordered_map.
353 */
354 const_iterator
355 end() const noexcept
356 { return _M_h.end(); }
357
358 const_iterator
359 cend() const noexcept
360 { return _M_h.end(); }
361 //@}
362
363 // modifiers.
364
365 /**
366 * @brief Attempts to build and insert a std::pair into the
367 * %unordered_map.
368 *
369 * @param __args Arguments used to generate a new pair instance (see
370 * std::piecewise_contruct for passing arguments to each
371 * part of the pair constructor).
372 *
373 * @return A pair, of which the first element is an iterator that points
374 * to the possibly inserted pair, and the second is a bool that
375 * is true if the pair was actually inserted.
376 *
377 * This function attempts to build and insert a (key, value) %pair into
378 * the %unordered_map.
379 * An %unordered_map relies on unique keys and thus a %pair is only
380 * inserted if its first element (the key) is not already present in the
381 * %unordered_map.
382 *
383 * Insertion requires amortized constant time.
384 */
385 template<typename... _Args>
386 std::pair<iterator, bool>
387 emplace(_Args&&... __args)
388 { return _M_h.emplace(std::forward<_Args>(__args)...); }
389
390 /**
391 * @brief Attempts to build and insert a std::pair into the
392 * %unordered_map.
393 *
394 * @param __pos An iterator that serves as a hint as to where the pair
395 * should be inserted.
396 * @param __args Arguments used to generate a new pair instance (see
397 * std::piecewise_contruct for passing arguments to each
398 * part of the pair constructor).
399 * @return An iterator that points to the element with key of the
400 * std::pair built from @a __args (may or may not be that
401 * std::pair).
402 *
403 * This function is not concerned about whether the insertion took place,
404 * and thus does not return a boolean like the single-argument emplace()
405 * does.
406 * Note that the first parameter is only a hint and can potentially
407 * improve the performance of the insertion process. A bad hint would
408 * cause no gains in efficiency.
409 *
410 * See
411 * https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
412 * for more on @a hinting.
413 *
414 * Insertion requires amortized constant time.
415 */
416 template<typename... _Args>
417 iterator
418 emplace_hint(const_iterator __pos, _Args&&... __args)
419 { return _M_h.emplace_hint(__pos, std::forward<_Args>(__args)...); }
420
421#if __cplusplus > 201402L
422 /// Extract a node.
423 node_type
424 extract(const_iterator __pos)
425 {
426 __glibcxx_assert(__pos != end());
427 return _M_h.extract(__pos);
428 }
429
430 /// Extract a node.
431 node_type
432 extract(const key_type& __key)
433 { return _M_h.extract(__key); }
434
435 /// Re-insert an extracted node.
436 insert_return_type
437 insert(node_type&& __nh)
438 { return _M_h._M_reinsert_node(std::move(__nh)); }
439
440 /// Re-insert an extracted node.
441 iterator
442 insert(const_iterator, node_type&& __nh)
443 { return _M_h._M_reinsert_node(std::move(__nh)).position; }
444
445#define __cpp_lib_unordered_map_try_emplace 201411
446 /**
447 * @brief Attempts to build and insert a std::pair into the
448 * %unordered_map.
449 *
450 * @param __k Key to use for finding a possibly existing pair in
451 * the unordered_map.
452 * @param __args Arguments used to generate the .second for a
453 * new pair instance.
454 *
455 * @return A pair, of which the first element is an iterator that points
456 * to the possibly inserted pair, and the second is a bool that
457 * is true if the pair was actually inserted.
458 *
459 * This function attempts to build and insert a (key, value) %pair into
460 * the %unordered_map.
461 * An %unordered_map relies on unique keys and thus a %pair is only
462 * inserted if its first element (the key) is not already present in the
463 * %unordered_map.
464 * If a %pair is not inserted, this function has no effect.
465 *
466 * Insertion requires amortized constant time.
467 */
468 template <typename... _Args>
469 pair<iterator, bool>
470 try_emplace(const key_type& __k, _Args&&... __args)
471 {
472 iterator __i = find(__k);
473 if (__i == end())
474 {
475 __i = emplace(std::piecewise_construct,
476 std::forward_as_tuple(__k),
477 std::forward_as_tuple(
478 std::forward<_Args>(__args)...))
479 .first;
480 return {__i, true};
481 }
482 return {__i, false};
483 }
484
485 // move-capable overload
486 template <typename... _Args>
487 pair<iterator, bool>
488 try_emplace(key_type&& __k, _Args&&... __args)
489 {
490 iterator __i = find(__k);
491 if (__i == end())
492 {
493 __i = emplace(std::piecewise_construct,
494 std::forward_as_tuple(std::move(__k)),
495 std::forward_as_tuple(
496 std::forward<_Args>(__args)...))
497 .first;
498 return {__i, true};
499 }
500 return {__i, false};
501 }
502
503 /**
504 * @brief Attempts to build and insert a std::pair into the
505 * %unordered_map.
506 *
507 * @param __hint An iterator that serves as a hint as to where the pair
508 * should be inserted.
509 * @param __k Key to use for finding a possibly existing pair in
510 * the unordered_map.
511 * @param __args Arguments used to generate the .second for a
512 * new pair instance.
513 * @return An iterator that points to the element with key of the
514 * std::pair built from @a __args (may or may not be that
515 * std::pair).
516 *
517 * This function is not concerned about whether the insertion took place,
518 * and thus does not return a boolean like the single-argument emplace()
519 * does. However, if insertion did not take place,
520 * this function has no effect.
521 * Note that the first parameter is only a hint and can potentially
522 * improve the performance of the insertion process. A bad hint would
523 * cause no gains in efficiency.
524 *
525 * See
526 * https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
527 * for more on @a hinting.
528 *
529 * Insertion requires amortized constant time.
530 */
531 template <typename... _Args>
532 iterator
533 try_emplace(const_iterator __hint, const key_type& __k,
534 _Args&&... __args)
535 {
536 iterator __i = find(__k);
537 if (__i == end())
538 __i = emplace_hint(__hint, std::piecewise_construct,
539 std::forward_as_tuple(__k),
540 std::forward_as_tuple(
541 std::forward<_Args>(__args)...));
542 return __i;
543 }
544
545 // move-capable overload
546 template <typename... _Args>
547 iterator
548 try_emplace(const_iterator __hint, key_type&& __k, _Args&&... __args)
549 {
550 iterator __i = find(__k);
551 if (__i == end())
552 __i = emplace_hint(__hint, std::piecewise_construct,
553 std::forward_as_tuple(std::move(__k)),
554 std::forward_as_tuple(
555 std::forward<_Args>(__args)...));
556 return __i;
557 }
558#endif // C++17
559
560 //@{
561 /**
562 * @brief Attempts to insert a std::pair into the %unordered_map.
563
564 * @param __x Pair to be inserted (see std::make_pair for easy
565 * creation of pairs).
566 *
567 * @return A pair, of which the first element is an iterator that
568 * points to the possibly inserted pair, and the second is
569 * a bool that is true if the pair was actually inserted.
570 *
571 * This function attempts to insert a (key, value) %pair into the
572 * %unordered_map. An %unordered_map relies on unique keys and thus a
573 * %pair is only inserted if its first element (the key) is not already
574 * present in the %unordered_map.
575 *
576 * Insertion requires amortized constant time.
577 */
578 std::pair<iterator, bool>
579 insert(const value_type& __x)
580 { return _M_h.insert(__x); }
581
582 // _GLIBCXX_RESOLVE_LIB_DEFECTS
583 // 2354. Unnecessary copying when inserting into maps with braced-init
584 std::pair<iterator, bool>
585 insert(value_type&& __x)
586 { return _M_h.insert(std::move(__x)); }
587
588 template<typename _Pair>
589 __enable_if_t<is_constructible<value_type, _Pair&&>::value,
590 pair<iterator, bool>>
591 insert(_Pair&& __x)
592 { return _M_h.emplace(std::forward<_Pair>(__x)); }
593 //@}
594
595 //@{
596 /**
597 * @brief Attempts to insert a std::pair into the %unordered_map.
598 * @param __hint An iterator that serves as a hint as to where the
599 * pair should be inserted.
600 * @param __x Pair to be inserted (see std::make_pair for easy creation
601 * of pairs).
602 * @return An iterator that points to the element with key of
603 * @a __x (may or may not be the %pair passed in).
604 *
605 * This function is not concerned about whether the insertion took place,
606 * and thus does not return a boolean like the single-argument insert()
607 * does. Note that the first parameter is only a hint and can
608 * potentially improve the performance of the insertion process. A bad
609 * hint would cause no gains in efficiency.
610 *
611 * See
612 * https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
613 * for more on @a hinting.
614 *
615 * Insertion requires amortized constant time.
616 */
617 iterator
618 insert(const_iterator __hint, const value_type& __x)
619 { return _M_h.insert(__hint, __x); }
620
621 // _GLIBCXX_RESOLVE_LIB_DEFECTS
622 // 2354. Unnecessary copying when inserting into maps with braced-init
623 iterator
624 insert(const_iterator __hint, value_type&& __x)
625 { return _M_h.insert(__hint, std::move(__x)); }
626
627 template<typename _Pair>
628 __enable_if_t<is_constructible<value_type, _Pair&&>::value, iterator>
629 insert(const_iterator __hint, _Pair&& __x)
630 { return _M_h.emplace_hint(__hint, std::forward<_Pair>(__x)); }
631 //@}
632
633 /**
634 * @brief A template function that attempts to insert a range of
635 * elements.
636 * @param __first Iterator pointing to the start of the range to be
637 * inserted.
638 * @param __last Iterator pointing to the end of the range.
639 *
640 * Complexity similar to that of the range constructor.
641 */
642 template<typename _InputIterator>
643 void
644 insert(_InputIterator __first, _InputIterator __last)
645 { _M_h.insert(__first, __last); }
646
647 /**
648 * @brief Attempts to insert a list of elements into the %unordered_map.
649 * @param __l A std::initializer_list<value_type> of elements
650 * to be inserted.
651 *
652 * Complexity similar to that of the range constructor.
653 */
654 void
655 insert(initializer_list<value_type> __l)
656 { _M_h.insert(__l); }
657
658
659#if __cplusplus > 201402L
660#define __cpp_lib_unordered_map_insertion 201411
661 /**
662 * @brief Attempts to insert a std::pair into the %unordered_map.
663 * @param __k Key to use for finding a possibly existing pair in
664 * the map.
665 * @param __obj Argument used to generate the .second for a pair
666 * instance.
667 *
668 * @return A pair, of which the first element is an iterator that
669 * points to the possibly inserted pair, and the second is
670 * a bool that is true if the pair was actually inserted.
671 *
672 * This function attempts to insert a (key, value) %pair into the
673 * %unordered_map. An %unordered_map relies on unique keys and thus a
674 * %pair is only inserted if its first element (the key) is not already
675 * present in the %unordered_map.
676 * If the %pair was already in the %unordered_map, the .second of
677 * the %pair is assigned from __obj.
678 *
679 * Insertion requires amortized constant time.
680 */
681 template <typename _Obj>
682 pair<iterator, bool>
683 insert_or_assign(const key_type& __k, _Obj&& __obj)
684 {
685 iterator __i = find(__k);
686 if (__i == end())
687 {
688 __i = emplace(std::piecewise_construct,
689 std::forward_as_tuple(__k),
690 std::forward_as_tuple(std::forward<_Obj>(__obj)))
691 .first;
692 return {__i, true};
693 }
694 (*__i).second = std::forward<_Obj>(__obj);
695 return {__i, false};
696 }
697
698 // move-capable overload
699 template <typename _Obj>
700 pair<iterator, bool>
701 insert_or_assign(key_type&& __k, _Obj&& __obj)
702 {
703 iterator __i = find(__k);
704 if (__i == end())
705 {
706 __i = emplace(std::piecewise_construct,
707 std::forward_as_tuple(std::move(__k)),
708 std::forward_as_tuple(std::forward<_Obj>(__obj)))
709 .first;
710 return {__i, true};
711 }
712 (*__i).second = std::forward<_Obj>(__obj);
713 return {__i, false};
714 }
715
716 /**
717 * @brief Attempts to insert a std::pair into the %unordered_map.
718 * @param __hint An iterator that serves as a hint as to where the
719 * pair should be inserted.
720 * @param __k Key to use for finding a possibly existing pair in
721 * the unordered_map.
722 * @param __obj Argument used to generate the .second for a pair
723 * instance.
724 * @return An iterator that points to the element with key of
725 * @a __x (may or may not be the %pair passed in).
726 *
727 * This function is not concerned about whether the insertion took place,
728 * and thus does not return a boolean like the single-argument insert()
729 * does.
730 * If the %pair was already in the %unordered map, the .second of
731 * the %pair is assigned from __obj.
732 * Note that the first parameter is only a hint and can
733 * potentially improve the performance of the insertion process. A bad
734 * hint would cause no gains in efficiency.
735 *
736 * See
737 * https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
738 * for more on @a hinting.
739 *
740 * Insertion requires amortized constant time.
741 */
742 template <typename _Obj>
743 iterator
744 insert_or_assign(const_iterator __hint, const key_type& __k,
745 _Obj&& __obj)
746 {
747 iterator __i = find(__k);
748 if (__i == end())
749 {
750 return emplace_hint(__hint, std::piecewise_construct,
751 std::forward_as_tuple(__k),
752 std::forward_as_tuple(
753 std::forward<_Obj>(__obj)));
754 }
755 (*__i).second = std::forward<_Obj>(__obj);
756 return __i;
757 }
758
759 // move-capable overload
760 template <typename _Obj>
761 iterator
762 insert_or_assign(const_iterator __hint, key_type&& __k, _Obj&& __obj)
763 {
764 iterator __i = find(__k);
765 if (__i == end())
766 {
767 return emplace_hint(__hint, std::piecewise_construct,
768 std::forward_as_tuple(std::move(__k)),
769 std::forward_as_tuple(
770 std::forward<_Obj>(__obj)));
771 }
772 (*__i).second = std::forward<_Obj>(__obj);
773 return __i;
774 }
775#endif
776
777 //@{
778 /**
779 * @brief Erases an element from an %unordered_map.
780 * @param __position An iterator pointing to the element to be erased.
781 * @return An iterator pointing to the element immediately following
782 * @a __position prior to the element being erased. If no such
783 * element exists, end() is returned.
784 *
785 * This function erases an element, pointed to by the given iterator,
786 * from an %unordered_map.
787 * Note that this function only erases the element, and that if the
788 * element is itself a pointer, the pointed-to memory is not touched in
789 * any way. Managing the pointer is the user's responsibility.
790 */
791 iterator
792 erase(const_iterator __position)
793 { return _M_h.erase(__position); }
794
795 // LWG 2059.
796 iterator
797 erase(iterator __position)
798 { return _M_h.erase(__position); }
799 //@}
800
801 /**
802 * @brief Erases elements according to the provided key.
803 * @param __x Key of element to be erased.
804 * @return The number of elements erased.
805 *
806 * This function erases all the elements located by the given key from
807 * an %unordered_map. For an %unordered_map the result of this function
808 * can only be 0 (not present) or 1 (present).
809 * Note that this function only erases the element, and that if the
810 * element is itself a pointer, the pointed-to memory is not touched in
811 * any way. Managing the pointer is the user's responsibility.
812 */
813 size_type
814 erase(const key_type& __x)
815 { return _M_h.erase(__x); }
816
817 /**
818 * @brief Erases a [__first,__last) range of elements from an
819 * %unordered_map.
820 * @param __first Iterator pointing to the start of the range to be
821 * erased.
822 * @param __last Iterator pointing to the end of the range to
823 * be erased.
824 * @return The iterator @a __last.
825 *
826 * This function erases a sequence of elements from an %unordered_map.
827 * Note that this function only erases the elements, and that if
828 * the element is itself a pointer, the pointed-to memory is not touched
829 * in any way. Managing the pointer is the user's responsibility.
830 */
831 iterator
832 erase(const_iterator __first, const_iterator __last)
833 { return _M_h.erase(__first, __last); }
834
835 /**
836 * Erases all elements in an %unordered_map.
837 * Note that this function only erases the elements, and that if the
838 * elements themselves are pointers, the pointed-to memory is not touched
839 * in any way. Managing the pointer is the user's responsibility.
840 */
841 void
842 clear() noexcept
843 { _M_h.clear(); }
844
845 /**
846 * @brief Swaps data with another %unordered_map.
847 * @param __x An %unordered_map of the same element and allocator
848 * types.
849 *
850 * This exchanges the elements between two %unordered_map in constant
851 * time.
852 * Note that the global std::swap() function is specialized such that
853 * std::swap(m1,m2) will feed to this function.
854 */
855 void
856 swap(unordered_map& __x)
857 noexcept( noexcept(_M_h.swap(__x._M_h)) )
858 { _M_h.swap(__x._M_h); }
859
860#if __cplusplus > 201402L
861 template<typename, typename, typename>
862 friend class std::_Hash_merge_helper;
863
864 template<typename _H2, typename _P2>
865 void
866 merge(unordered_map<_Key, _Tp, _H2, _P2, _Alloc>& __source)
867 {
868 using _Merge_helper = _Hash_merge_helper<unordered_map, _H2, _P2>;
869 _M_h._M_merge_unique(_Merge_helper::_S_get_table(__source));
870 }
871
872 template<typename _H2, typename _P2>
873 void
874 merge(unordered_map<_Key, _Tp, _H2, _P2, _Alloc>&& __source)
875 { merge(__source); }
876
877 template<typename _H2, typename _P2>
878 void
879 merge(unordered_multimap<_Key, _Tp, _H2, _P2, _Alloc>& __source)
880 {
881 using _Merge_helper = _Hash_merge_helper<unordered_map, _H2, _P2>;
882 _M_h._M_merge_unique(_Merge_helper::_S_get_table(__source));
883 }
884
885 template<typename _H2, typename _P2>
886 void
887 merge(unordered_multimap<_Key, _Tp, _H2, _P2, _Alloc>&& __source)
888 { merge(__source); }
889#endif // C++17
890
891 // observers.
892
893 /// Returns the hash functor object with which the %unordered_map was
894 /// constructed.
895 hasher
896 hash_function() const
897 { return _M_h.hash_function(); }
898
899 /// Returns the key comparison object with which the %unordered_map was
900 /// constructed.
901 key_equal
902 key_eq() const
903 { return _M_h.key_eq(); }
904
905 // lookup.
906
907 //@{
908 /**
909 * @brief Tries to locate an element in an %unordered_map.
910 * @param __x Key to be located.
911 * @return Iterator pointing to sought-after element, or end() if not
912 * found.
913 *
914 * This function takes a key and tries to locate the element with which
915 * the key matches. If successful the function returns an iterator
916 * pointing to the sought after element. If unsuccessful it returns the
917 * past-the-end ( @c end() ) iterator.
918 */
919 iterator
920 find(const key_type& __x)
921 { return _M_h.find(__x); }
922
923 const_iterator
924 find(const key_type& __x) const
925 { return _M_h.find(__x); }
926 //@}
927
928 /**
929 * @brief Finds the number of elements.
930 * @param __x Key to count.
931 * @return Number of elements with specified key.
932 *
933 * This function only makes sense for %unordered_multimap; for
934 * %unordered_map the result will either be 0 (not present) or 1
935 * (present).
936 */
937 size_type
938 count(const key_type& __x) const
939 { return _M_h.count(__x); }
940
941 //@{
942 /**
943 * @brief Finds a subsequence matching given key.
944 * @param __x Key to be located.
945 * @return Pair of iterators that possibly points to the subsequence
946 * matching given key.
947 *
948 * This function probably only makes sense for %unordered_multimap.
949 */
950 std::pair<iterator, iterator>
951 equal_range(const key_type& __x)
952 { return _M_h.equal_range(__x); }
953
954 std::pair<const_iterator, const_iterator>
955 equal_range(const key_type& __x) const
956 { return _M_h.equal_range(__x); }
957 //@}
958
959 //@{
960 /**
961 * @brief Subscript ( @c [] ) access to %unordered_map data.
962 * @param __k The key for which data should be retrieved.
963 * @return A reference to the data of the (key,data) %pair.
964 *
965 * Allows for easy lookup with the subscript ( @c [] )operator. Returns
966 * data associated with the key specified in subscript. If the key does
967 * not exist, a pair with that key is created using default values, which
968 * is then returned.
969 *
970 * Lookup requires constant time.
971 */
972 mapped_type&
973 operator[](const key_type& __k)
974 { return _M_h[__k]; }
975
976 mapped_type&
977 operator[](key_type&& __k)
978 { return _M_h[std::move(__k)]; }
979 //@}
980
981 //@{
982 /**
983 * @brief Access to %unordered_map data.
984 * @param __k The key for which data should be retrieved.
985 * @return A reference to the data whose key is equal to @a __k, if
986 * such a data is present in the %unordered_map.
987 * @throw std::out_of_range If no such data is present.
988 */
989 mapped_type&
990 at(const key_type& __k)
991 { return _M_h.at(__k); }
992
993 const mapped_type&
994 at(const key_type& __k) const
995 { return _M_h.at(__k); }
996 //@}
997
998 // bucket interface.
999
1000 /// Returns the number of buckets of the %unordered_map.
1001 size_type
1002 bucket_count() const noexcept
1003 { return _M_h.bucket_count(); }
1004
1005 /// Returns the maximum number of buckets of the %unordered_map.
1006 size_type
1007 max_bucket_count() const noexcept
1008 { return _M_h.max_bucket_count(); }
1009
1010 /*
1011 * @brief Returns the number of elements in a given bucket.
1012 * @param __n A bucket index.
1013 * @return The number of elements in the bucket.
1014 */
1015 size_type
1016 bucket_size(size_type __n) const
1017 { return _M_h.bucket_size(__n); }
1018
1019 /*
1020 * @brief Returns the bucket index of a given element.
1021 * @param __key A key instance.
1022 * @return The key bucket index.
1023 */
1024 size_type
1025 bucket(const key_type& __key) const
1026 { return _M_h.bucket(__key); }
1027
1028 /**
1029 * @brief Returns a read/write iterator pointing to the first bucket
1030 * element.
1031 * @param __n The bucket index.
1032 * @return A read/write local iterator.
1033 */
1034 local_iterator
1035 begin(size_type __n)
1036 { return _M_h.begin(__n); }
1037
1038 //@{
1039 /**
1040 * @brief Returns a read-only (constant) iterator pointing to the first
1041 * bucket element.
1042 * @param __n The bucket index.
1043 * @return A read-only local iterator.
1044 */
1045 const_local_iterator
1046 begin(size_type __n) const
1047 { return _M_h.begin(__n); }
1048
1049 const_local_iterator
1050 cbegin(size_type __n) const
1051 { return _M_h.cbegin(__n); }
1052 //@}
1053
1054 /**
1055 * @brief Returns a read/write iterator pointing to one past the last
1056 * bucket elements.
1057 * @param __n The bucket index.
1058 * @return A read/write local iterator.
1059 */
1060 local_iterator
1061 end(size_type __n)
1062 { return _M_h.end(__n); }
1063
1064 //@{
1065 /**
1066 * @brief Returns a read-only (constant) iterator pointing to one past
1067 * the last bucket elements.
1068 * @param __n The bucket index.
1069 * @return A read-only local iterator.
1070 */
1071 const_local_iterator
1072 end(size_type __n) const
1073 { return _M_h.end(__n); }
1074
1075 const_local_iterator
1076 cend(size_type __n) const
1077 { return _M_h.cend(__n); }
1078 //@}
1079
1080 // hash policy.
1081
1082 /// Returns the average number of elements per bucket.
1083 float
1084 load_factor() const noexcept
1085 { return _M_h.load_factor(); }
1086
1087 /// Returns a positive number that the %unordered_map tries to keep the
1088 /// load factor less than or equal to.
1089 float
1090 max_load_factor() const noexcept
1091 { return _M_h.max_load_factor(); }
1092
1093 /**
1094 * @brief Change the %unordered_map maximum load factor.
1095 * @param __z The new maximum load factor.
1096 */
1097 void
1098 max_load_factor(float __z)
1099 { _M_h.max_load_factor(__z); }
1100
1101 /**
1102 * @brief May rehash the %unordered_map.
1103 * @param __n The new number of buckets.
1104 *
1105 * Rehash will occur only if the new number of buckets respect the
1106 * %unordered_map maximum load factor.
1107 */
1108 void
1109 rehash(size_type __n)
1110 { _M_h.rehash(__n); }
1111
1112 /**
1113 * @brief Prepare the %unordered_map for a specified number of
1114 * elements.
1115 * @param __n Number of elements required.
1116 *
1117 * Same as rehash(ceil(n / max_load_factor())).
1118 */
1119 void
1120 reserve(size_type __n)
1121 { _M_h.reserve(__n); }
1122
1123 template<typename _Key1, typename _Tp1, typename _Hash1, typename _Pred1,
1124 typename _Alloc1>
1125 friend bool
1126 operator==(const unordered_map<_Key1, _Tp1, _Hash1, _Pred1, _Alloc1>&,
1127 const unordered_map<_Key1, _Tp1, _Hash1, _Pred1, _Alloc1>&);
1128 };
1129
1130#if __cpp_deduction_guides >= 201606
1131
1132 template<typename _InputIterator,
1133 typename _Hash = hash<__iter_key_t<_InputIterator>>,
1134 typename _Pred = equal_to<__iter_key_t<_InputIterator>>,
1135 typename _Allocator = allocator<__iter_to_alloc_t<_InputIterator>>,
1136 typename = _RequireInputIter<_InputIterator>,
1137 typename = _RequireAllocator<_Allocator>>
1138 unordered_map(_InputIterator, _InputIterator,
1139 typename unordered_map<int, int>::size_type = {},
1140 _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
1141 -> unordered_map<__iter_key_t<_InputIterator>,
1142 __iter_val_t<_InputIterator>,
1143 _Hash, _Pred, _Allocator>;
1144
1145 template<typename _Key, typename _Tp, typename _Hash = hash<_Key>,
1146 typename _Pred = equal_to<_Key>,
1147 typename _Allocator = allocator<pair<const _Key, _Tp>>,
1148 typename = _RequireAllocator<_Allocator>>
1149 unordered_map(initializer_list<pair<_Key, _Tp>>,
1150 typename unordered_map<int, int>::size_type = {},
1151 _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
1152 -> unordered_map<_Key, _Tp, _Hash, _Pred, _Allocator>;
1153
1154 template<typename _InputIterator, typename _Allocator,
1155 typename = _RequireInputIter<_InputIterator>,
1156 typename = _RequireAllocator<_Allocator>>
1157 unordered_map(_InputIterator, _InputIterator,
1158 typename unordered_map<int, int>::size_type, _Allocator)
1159 -> unordered_map<__iter_key_t<_InputIterator>,
1160 __iter_val_t<_InputIterator>,
1161 hash<__iter_key_t<_InputIterator>>,
1162 equal_to<__iter_key_t<_InputIterator>>,
1163 _Allocator>;
1164
1165 template<typename _InputIterator, typename _Allocator,
1166 typename = _RequireInputIter<_InputIterator>,
1167 typename = _RequireAllocator<_Allocator>>
1168 unordered_map(_InputIterator, _InputIterator, _Allocator)
1169 -> unordered_map<__iter_key_t<_InputIterator>,
1170 __iter_val_t<_InputIterator>,
1171 hash<__iter_key_t<_InputIterator>>,
1172 equal_to<__iter_key_t<_InputIterator>>,
1173 _Allocator>;
1174
1175 template<typename _InputIterator, typename _Hash, typename _Allocator,
1176 typename = _RequireInputIter<_InputIterator>,
1177 typename = _RequireAllocator<_Allocator>>
1178 unordered_map(_InputIterator, _InputIterator,
1179 typename unordered_map<int, int>::size_type,
1180 _Hash, _Allocator)
1181 -> unordered_map<__iter_key_t<_InputIterator>,
1182 __iter_val_t<_InputIterator>, _Hash,
1183 equal_to<__iter_key_t<_InputIterator>>, _Allocator>;
1184
1185 template<typename _Key, typename _Tp, typename _Allocator,
1186 typename = _RequireAllocator<_Allocator>>
1187 unordered_map(initializer_list<pair<_Key, _Tp>>,
1188 typename unordered_map<int, int>::size_type,
1189 _Allocator)
1190 -> unordered_map<_Key, _Tp, hash<_Key>, equal_to<_Key>, _Allocator>;
1191
1192 template<typename _Key, typename _Tp, typename _Allocator,
1193 typename = _RequireAllocator<_Allocator>>
1194 unordered_map(initializer_list<pair<_Key, _Tp>>, _Allocator)
1195 -> unordered_map<_Key, _Tp, hash<_Key>, equal_to<_Key>, _Allocator>;
1196
1197 template<typename _Key, typename _Tp, typename _Hash, typename _Allocator,
1198 typename = _RequireAllocator<_Allocator>>
1199 unordered_map(initializer_list<pair<_Key, _Tp>>,
1200 typename unordered_map<int, int>::size_type,
1201 _Hash, _Allocator)
1202 -> unordered_map<_Key, _Tp, _Hash, equal_to<_Key>, _Allocator>;
1203
1204#endif
1205
1206 /**
1207 * @brief A standard container composed of equivalent keys
1208 * (possibly containing multiple of each key value) that associates
1209 * values of another type with the keys.
1210 *
1211 * @ingroup unordered_associative_containers
1212 *
1213 * @tparam _Key Type of key objects.
1214 * @tparam _Tp Type of mapped objects.
1215 * @tparam _Hash Hashing function object type, defaults to hash<_Value>.
1216 * @tparam _Pred Predicate function object type, defaults
1217 * to equal_to<_Value>.
1218 * @tparam _Alloc Allocator type, defaults to
1219 * std::allocator<std::pair<const _Key, _Tp>>.
1220 *
1221 * Meets the requirements of a <a href="tables.html#65">container</a>, and
1222 * <a href="tables.html#xx">unordered associative container</a>
1223 *
1224 * The resulting value type of the container is std::pair<const _Key, _Tp>.
1225 *
1226 * Base is _Hashtable, dispatched at compile time via template
1227 * alias __ummap_hashtable.
1228 */
1229 template<typename _Key, typename _Tp,
1230 typename _Hash = hash<_Key>,
1231 typename _Pred = equal_to<_Key>,
1232 typename _Alloc = allocator<std::pair<const _Key, _Tp>>>
1233 class unordered_multimap
1234 {
1235 typedef __ummap_hashtable<_Key, _Tp, _Hash, _Pred, _Alloc> _Hashtable;
1236 _Hashtable _M_h;
1237
1238 public:
1239 // typedefs:
1240 //@{
1241 /// Public typedefs.
1242 typedef typename _Hashtable::key_type key_type;
1243 typedef typename _Hashtable::value_type value_type;
1244 typedef typename _Hashtable::mapped_type mapped_type;
1245 typedef typename _Hashtable::hasher hasher;
1246 typedef typename _Hashtable::key_equal key_equal;
1247 typedef typename _Hashtable::allocator_type allocator_type;
1248 //@}
1249
1250 //@{
1251 /// Iterator-related typedefs.
1252 typedef typename _Hashtable::pointer pointer;
1253 typedef typename _Hashtable::const_pointer const_pointer;
1254 typedef typename _Hashtable::reference reference;
1255 typedef typename _Hashtable::const_reference const_reference;
1256 typedef typename _Hashtable::iterator iterator;
1257 typedef typename _Hashtable::const_iterator const_iterator;
1258 typedef typename _Hashtable::local_iterator local_iterator;
1259 typedef typename _Hashtable::const_local_iterator const_local_iterator;
1260 typedef typename _Hashtable::size_type size_type;
1261 typedef typename _Hashtable::difference_type difference_type;
1262 //@}
1263
1264#if __cplusplus > 201402L
1265 using node_type = typename _Hashtable::node_type;
1266#endif
1267
1268 //construct/destroy/copy
1269
1270 /// Default constructor.
1271 unordered_multimap() = default;
1272
1273 /**
1274 * @brief Default constructor creates no elements.
1275 * @param __n Mnimal initial number of buckets.
1276 * @param __hf A hash functor.
1277 * @param __eql A key equality functor.
1278 * @param __a An allocator object.
1279 */
1280 explicit
1281 unordered_multimap(size_type __n,
1282 const hasher& __hf = hasher(),
1283 const key_equal& __eql = key_equal(),
1284 const allocator_type& __a = allocator_type())
1285 : _M_h(__n, __hf, __eql, __a)
1286 { }
1287
1288 /**
1289 * @brief Builds an %unordered_multimap from a range.
1290 * @param __first An input iterator.
1291 * @param __last An input iterator.
1292 * @param __n Minimal initial number of buckets.
1293 * @param __hf A hash functor.
1294 * @param __eql A key equality functor.
1295 * @param __a An allocator object.
1296 *
1297 * Create an %unordered_multimap consisting of copies of the elements
1298 * from [__first,__last). This is linear in N (where N is
1299 * distance(__first,__last)).
1300 */
1301 template<typename _InputIterator>
1302 unordered_multimap(_InputIterator __first, _InputIterator __last,
1303 size_type __n = 0,
1304 const hasher& __hf = hasher(),
1305 const key_equal& __eql = key_equal(),
1306 const allocator_type& __a = allocator_type())
1307 : _M_h(__first, __last, __n, __hf, __eql, __a)
1308 { }
1309
1310 /// Copy constructor.
1311 unordered_multimap(const unordered_multimap&) = default;
1312
1313 /// Move constructor.
1314 unordered_multimap(unordered_multimap&&) = default;
1315
1316 /**
1317 * @brief Creates an %unordered_multimap with no elements.
1318 * @param __a An allocator object.
1319 */
1320 explicit
1321 unordered_multimap(const allocator_type& __a)
1322 : _M_h(__a)
1323 { }
1324
1325 /*
1326 * @brief Copy constructor with allocator argument.
1327 * @param __uset Input %unordered_multimap to copy.
1328 * @param __a An allocator object.
1329 */
1330 unordered_multimap(const unordered_multimap& __ummap,
1331 const allocator_type& __a)
1332 : _M_h(__ummap._M_h, __a)
1333 { }
1334
1335 /*
1336 * @brief Move constructor with allocator argument.
1337 * @param __uset Input %unordered_multimap to move.
1338 * @param __a An allocator object.
1339 */
1340 unordered_multimap(unordered_multimap&& __ummap,
1341 const allocator_type& __a)
1342 : _M_h(std::move(__ummap._M_h), __a)
1343 { }
1344
1345 /**
1346 * @brief Builds an %unordered_multimap from an initializer_list.
1347 * @param __l An initializer_list.
1348 * @param __n Minimal initial number of buckets.
1349 * @param __hf A hash functor.
1350 * @param __eql A key equality functor.
1351 * @param __a An allocator object.
1352 *
1353 * Create an %unordered_multimap consisting of copies of the elements in
1354 * the list. This is linear in N (where N is @a __l.size()).
1355 */
1356 unordered_multimap(initializer_list<value_type> __l,
1357 size_type __n = 0,
1358 const hasher& __hf = hasher(),
1359 const key_equal& __eql = key_equal(),
1360 const allocator_type& __a = allocator_type())
1361 : _M_h(__l, __n, __hf, __eql, __a)
1362 { }
1363
1364 unordered_multimap(size_type __n, const allocator_type& __a)
1365 : unordered_multimap(__n, hasher(), key_equal(), __a)
1366 { }
1367
1368 unordered_multimap(size_type __n, const hasher& __hf,
1369 const allocator_type& __a)
1370 : unordered_multimap(__n, __hf, key_equal(), __a)
1371 { }
1372
1373 template<typename _InputIterator>
1374 unordered_multimap(_InputIterator __first, _InputIterator __last,
1375 size_type __n,
1376 const allocator_type& __a)
1377 : unordered_multimap(__first, __last, __n, hasher(), key_equal(), __a)
1378 { }
1379
1380 template<typename _InputIterator>
1381 unordered_multimap(_InputIterator __first, _InputIterator __last,
1382 size_type __n, const hasher& __hf,
1383 const allocator_type& __a)
1384 : unordered_multimap(__first, __last, __n, __hf, key_equal(), __a)
1385 { }
1386
1387 unordered_multimap(initializer_list<value_type> __l,
1388 size_type __n,
1389 const allocator_type& __a)
1390 : unordered_multimap(__l, __n, hasher(), key_equal(), __a)
1391 { }
1392
1393 unordered_multimap(initializer_list<value_type> __l,
1394 size_type __n, const hasher& __hf,
1395 const allocator_type& __a)
1396 : unordered_multimap(__l, __n, __hf, key_equal(), __a)
1397 { }
1398
1399 /// Copy assignment operator.
1400 unordered_multimap&
1401 operator=(const unordered_multimap&) = default;
1402
1403 /// Move assignment operator.
1404 unordered_multimap&
1405 operator=(unordered_multimap&&) = default;
1406
1407 /**
1408 * @brief %Unordered_multimap list assignment operator.
1409 * @param __l An initializer_list.
1410 *
1411 * This function fills an %unordered_multimap with copies of the
1412 * elements in the initializer list @a __l.
1413 *
1414 * Note that the assignment completely changes the %unordered_multimap
1415 * and that the resulting %unordered_multimap's size is the same as the
1416 * number of elements assigned.
1417 */
1418 unordered_multimap&
1419 operator=(initializer_list<value_type> __l)
1420 {
1421 _M_h = __l;
1422 return *this;
1423 }
1424
1425 /// Returns the allocator object used by the %unordered_multimap.
1426 allocator_type
1427 get_allocator() const noexcept
1428 { return _M_h.get_allocator(); }
1429
1430 // size and capacity:
1431
1432 /// Returns true if the %unordered_multimap is empty.
1433 bool
1434 empty() const noexcept
1435 { return _M_h.empty(); }
1436
1437 /// Returns the size of the %unordered_multimap.
1438 size_type
1439 size() const noexcept
1440 { return _M_h.size(); }
1441
1442 /// Returns the maximum size of the %unordered_multimap.
1443 size_type
1444 max_size() const noexcept
1445 { return _M_h.max_size(); }
1446
1447 // iterators.
1448
1449 /**
1450 * Returns a read/write iterator that points to the first element in the
1451 * %unordered_multimap.
1452 */
1453 iterator
1454 begin() noexcept
1455 { return _M_h.begin(); }
1456
1457 //@{
1458 /**
1459 * Returns a read-only (constant) iterator that points to the first
1460 * element in the %unordered_multimap.
1461 */
1462 const_iterator
1463 begin() const noexcept
1464 { return _M_h.begin(); }
1465
1466 const_iterator
1467 cbegin() const noexcept
1468 { return _M_h.begin(); }
1469 //@}
1470
1471 /**
1472 * Returns a read/write iterator that points one past the last element in
1473 * the %unordered_multimap.
1474 */
1475 iterator
1476 end() noexcept
1477 { return _M_h.end(); }
1478
1479 //@{
1480 /**
1481 * Returns a read-only (constant) iterator that points one past the last
1482 * element in the %unordered_multimap.
1483 */
1484 const_iterator
1485 end() const noexcept
1486 { return _M_h.end(); }
1487
1488 const_iterator
1489 cend() const noexcept
1490 { return _M_h.end(); }
1491 //@}
1492
1493 // modifiers.
1494
1495 /**
1496 * @brief Attempts to build and insert a std::pair into the
1497 * %unordered_multimap.
1498 *
1499 * @param __args Arguments used to generate a new pair instance (see
1500 * std::piecewise_contruct for passing arguments to each
1501 * part of the pair constructor).
1502 *
1503 * @return An iterator that points to the inserted pair.
1504 *
1505 * This function attempts to build and insert a (key, value) %pair into
1506 * the %unordered_multimap.
1507 *
1508 * Insertion requires amortized constant time.
1509 */
1510 template<typename... _Args>
1511 iterator
1512 emplace(_Args&&... __args)
1513 { return _M_h.emplace(std::forward<_Args>(__args)...); }
1514
1515 /**
1516 * @brief Attempts to build and insert a std::pair into the
1517 * %unordered_multimap.
1518 *
1519 * @param __pos An iterator that serves as a hint as to where the pair
1520 * should be inserted.
1521 * @param __args Arguments used to generate a new pair instance (see
1522 * std::piecewise_contruct for passing arguments to each
1523 * part of the pair constructor).
1524 * @return An iterator that points to the element with key of the
1525 * std::pair built from @a __args.
1526 *
1527 * Note that the first parameter is only a hint and can potentially
1528 * improve the performance of the insertion process. A bad hint would
1529 * cause no gains in efficiency.
1530 *
1531 * See
1532 * https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
1533 * for more on @a hinting.
1534 *
1535 * Insertion requires amortized constant time.
1536 */
1537 template<typename... _Args>
1538 iterator
1539 emplace_hint(const_iterator __pos, _Args&&... __args)
1540 { return _M_h.emplace_hint(__pos, std::forward<_Args>(__args)...); }
1541
1542 //@{
1543 /**
1544 * @brief Inserts a std::pair into the %unordered_multimap.
1545 * @param __x Pair to be inserted (see std::make_pair for easy
1546 * creation of pairs).
1547 *
1548 * @return An iterator that points to the inserted pair.
1549 *
1550 * Insertion requires amortized constant time.
1551 */
1552 iterator
1553 insert(const value_type& __x)
1554 { return _M_h.insert(__x); }
1555
1556 iterator
1557 insert(value_type&& __x)
1558 { return _M_h.insert(std::move(__x)); }
1559
1560 template<typename _Pair>
1561 __enable_if_t<is_constructible<value_type, _Pair&&>::value, iterator>
1562 insert(_Pair&& __x)
1563 { return _M_h.emplace(std::forward<_Pair>(__x)); }
1564 //@}
1565
1566 //@{
1567 /**
1568 * @brief Inserts a std::pair into the %unordered_multimap.
1569 * @param __hint An iterator that serves as a hint as to where the
1570 * pair should be inserted.
1571 * @param __x Pair to be inserted (see std::make_pair for easy creation
1572 * of pairs).
1573 * @return An iterator that points to the element with key of
1574 * @a __x (may or may not be the %pair passed in).
1575 *
1576 * Note that the first parameter is only a hint and can potentially
1577 * improve the performance of the insertion process. A bad hint would
1578 * cause no gains in efficiency.
1579 *
1580 * See
1581 * https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
1582 * for more on @a hinting.
1583 *
1584 * Insertion requires amortized constant time.
1585 */
1586 iterator
1587 insert(const_iterator __hint, const value_type& __x)
1588 { return _M_h.insert(__hint, __x); }
1589
1590 // _GLIBCXX_RESOLVE_LIB_DEFECTS
1591 // 2354. Unnecessary copying when inserting into maps with braced-init
1592 iterator
1593 insert(const_iterator __hint, value_type&& __x)
1594 { return _M_h.insert(__hint, std::move(__x)); }
1595
1596 template<typename _Pair>
1597 __enable_if_t<is_constructible<value_type, _Pair&&>::value, iterator>
1598 insert(const_iterator __hint, _Pair&& __x)
1599 { return _M_h.emplace_hint(__hint, std::forward<_Pair>(__x)); }
1600 //@}
1601
1602 /**
1603 * @brief A template function that attempts to insert a range of
1604 * elements.
1605 * @param __first Iterator pointing to the start of the range to be
1606 * inserted.
1607 * @param __last Iterator pointing to the end of the range.
1608 *
1609 * Complexity similar to that of the range constructor.
1610 */
1611 template<typename _InputIterator>
1612 void
1613 insert(_InputIterator __first, _InputIterator __last)
1614 { _M_h.insert(__first, __last); }
1615
1616 /**
1617 * @brief Attempts to insert a list of elements into the
1618 * %unordered_multimap.
1619 * @param __l A std::initializer_list<value_type> of elements
1620 * to be inserted.
1621 *
1622 * Complexity similar to that of the range constructor.
1623 */
1624 void
1625 insert(initializer_list<value_type> __l)
1626 { _M_h.insert(__l); }
1627
1628#if __cplusplus > 201402L
1629 /// Extract a node.
1630 node_type
1631 extract(const_iterator __pos)
1632 {
1633 __glibcxx_assert(__pos != end());
1634 return _M_h.extract(__pos);
1635 }
1636
1637 /// Extract a node.
1638 node_type
1639 extract(const key_type& __key)
1640 { return _M_h.extract(__key); }
1641
1642 /// Re-insert an extracted node.
1643 iterator
1644 insert(node_type&& __nh)
1645 { return _M_h._M_reinsert_node_multi(cend(), std::move(__nh)); }
1646
1647 /// Re-insert an extracted node.
1648 iterator
1649 insert(const_iterator __hint, node_type&& __nh)
1650 { return _M_h._M_reinsert_node_multi(__hint, std::move(__nh)); }
1651#endif // C++17
1652
1653 //@{
1654 /**
1655 * @brief Erases an element from an %unordered_multimap.
1656 * @param __position An iterator pointing to the element to be erased.
1657 * @return An iterator pointing to the element immediately following
1658 * @a __position prior to the element being erased. If no such
1659 * element exists, end() is returned.
1660 *
1661 * This function erases an element, pointed to by the given iterator,
1662 * from an %unordered_multimap.
1663 * Note that this function only erases the element, and that if the
1664 * element is itself a pointer, the pointed-to memory is not touched in
1665 * any way. Managing the pointer is the user's responsibility.
1666 */
1667 iterator
1668 erase(const_iterator __position)
1669 { return _M_h.erase(__position); }
1670
1671 // LWG 2059.
1672 iterator
1673 erase(iterator __position)
1674 { return _M_h.erase(__position); }
1675 //@}
1676
1677 /**
1678 * @brief Erases elements according to the provided key.
1679 * @param __x Key of elements to be erased.
1680 * @return The number of elements erased.
1681 *
1682 * This function erases all the elements located by the given key from
1683 * an %unordered_multimap.
1684 * Note that this function only erases the element, and that if the
1685 * element is itself a pointer, the pointed-to memory is not touched in
1686 * any way. Managing the pointer is the user's responsibility.
1687 */
1688 size_type
1689 erase(const key_type& __x)
1690 { return _M_h.erase(__x); }
1691
1692 /**
1693 * @brief Erases a [__first,__last) range of elements from an
1694 * %unordered_multimap.
1695 * @param __first Iterator pointing to the start of the range to be
1696 * erased.
1697 * @param __last Iterator pointing to the end of the range to
1698 * be erased.
1699 * @return The iterator @a __last.
1700 *
1701 * This function erases a sequence of elements from an
1702 * %unordered_multimap.
1703 * Note that this function only erases the elements, and that if
1704 * the element is itself a pointer, the pointed-to memory is not touched
1705 * in any way. Managing the pointer is the user's responsibility.
1706 */
1707 iterator
1708 erase(const_iterator __first, const_iterator __last)
1709 { return _M_h.erase(__first, __last); }
1710
1711 /**
1712 * Erases all elements in an %unordered_multimap.
1713 * Note that this function only erases the elements, and that if the
1714 * elements themselves are pointers, the pointed-to memory is not touched
1715 * in any way. Managing the pointer is the user's responsibility.
1716 */
1717 void
1718 clear() noexcept
1719 { _M_h.clear(); }
1720
1721 /**
1722 * @brief Swaps data with another %unordered_multimap.
1723 * @param __x An %unordered_multimap of the same element and allocator
1724 * types.
1725 *
1726 * This exchanges the elements between two %unordered_multimap in
1727 * constant time.
1728 * Note that the global std::swap() function is specialized such that
1729 * std::swap(m1,m2) will feed to this function.
1730 */
1731 void
1732 swap(unordered_multimap& __x)
1733 noexcept( noexcept(_M_h.swap(__x._M_h)) )
1734 { _M_h.swap(__x._M_h); }
1735
1736#if __cplusplus > 201402L
1737 template<typename, typename, typename>
1738 friend class std::_Hash_merge_helper;
1739
1740 template<typename _H2, typename _P2>
1741 void
1742 merge(unordered_multimap<_Key, _Tp, _H2, _P2, _Alloc>& __source)
1743 {
1744 using _Merge_helper
1745 = _Hash_merge_helper<unordered_multimap, _H2, _P2>;
1746 _M_h._M_merge_multi(_Merge_helper::_S_get_table(__source));
1747 }
1748
1749 template<typename _H2, typename _P2>
1750 void
1751 merge(unordered_multimap<_Key, _Tp, _H2, _P2, _Alloc>&& __source)
1752 { merge(__source); }
1753
1754 template<typename _H2, typename _P2>
1755 void
1756 merge(unordered_map<_Key, _Tp, _H2, _P2, _Alloc>& __source)
1757 {
1758 using _Merge_helper
1759 = _Hash_merge_helper<unordered_multimap, _H2, _P2>;
1760 _M_h._M_merge_multi(_Merge_helper::_S_get_table(__source));
1761 }
1762
1763 template<typename _H2, typename _P2>
1764 void
1765 merge(unordered_map<_Key, _Tp, _H2, _P2, _Alloc>&& __source)
1766 { merge(__source); }
1767#endif // C++17
1768
1769 // observers.
1770
1771 /// Returns the hash functor object with which the %unordered_multimap
1772 /// was constructed.
1773 hasher
1774 hash_function() const
1775 { return _M_h.hash_function(); }
1776
1777 /// Returns the key comparison object with which the %unordered_multimap
1778 /// was constructed.
1779 key_equal
1780 key_eq() const
1781 { return _M_h.key_eq(); }
1782
1783 // lookup.
1784
1785 //@{
1786 /**
1787 * @brief Tries to locate an element in an %unordered_multimap.
1788 * @param __x Key to be located.
1789 * @return Iterator pointing to sought-after element, or end() if not
1790 * found.
1791 *
1792 * This function takes a key and tries to locate the element with which
1793 * the key matches. If successful the function returns an iterator
1794 * pointing to the sought after element. If unsuccessful it returns the
1795 * past-the-end ( @c end() ) iterator.
1796 */
1797 iterator
1798 find(const key_type& __x)
1799 { return _M_h.find(__x); }
1800
1801 const_iterator
1802 find(const key_type& __x) const
1803 { return _M_h.find(__x); }
1804 //@}
1805
1806 /**
1807 * @brief Finds the number of elements.
1808 * @param __x Key to count.
1809 * @return Number of elements with specified key.
1810 */
1811 size_type
1812 count(const key_type& __x) const
1813 { return _M_h.count(__x); }
1814
1815 //@{
1816 /**
1817 * @brief Finds a subsequence matching given key.
1818 * @param __x Key to be located.
1819 * @return Pair of iterators that possibly points to the subsequence
1820 * matching given key.
1821 */
1822 std::pair<iterator, iterator>
1823 equal_range(const key_type& __x)
1824 { return _M_h.equal_range(__x); }
1825
1826 std::pair<const_iterator, const_iterator>
1827 equal_range(const key_type& __x) const
1828 { return _M_h.equal_range(__x); }
1829 //@}
1830
1831 // bucket interface.
1832
1833 /// Returns the number of buckets of the %unordered_multimap.
1834 size_type
1835 bucket_count() const noexcept
1836 { return _M_h.bucket_count(); }
1837
1838 /// Returns the maximum number of buckets of the %unordered_multimap.
1839 size_type
1840 max_bucket_count() const noexcept
1841 { return _M_h.max_bucket_count(); }
1842
1843 /*
1844 * @brief Returns the number of elements in a given bucket.
1845 * @param __n A bucket index.
1846 * @return The number of elements in the bucket.
1847 */
1848 size_type
1849 bucket_size(size_type __n) const
1850 { return _M_h.bucket_size(__n); }
1851
1852 /*
1853 * @brief Returns the bucket index of a given element.
1854 * @param __key A key instance.
1855 * @return The key bucket index.
1856 */
1857 size_type
1858 bucket(const key_type& __key) const
1859 { return _M_h.bucket(__key); }
1860
1861 /**
1862 * @brief Returns a read/write iterator pointing to the first bucket
1863 * element.
1864 * @param __n The bucket index.
1865 * @return A read/write local iterator.
1866 */
1867 local_iterator
1868 begin(size_type __n)
1869 { return _M_h.begin(__n); }
1870
1871 //@{
1872 /**
1873 * @brief Returns a read-only (constant) iterator pointing to the first
1874 * bucket element.
1875 * @param __n The bucket index.
1876 * @return A read-only local iterator.
1877 */
1878 const_local_iterator
1879 begin(size_type __n) const
1880 { return _M_h.begin(__n); }
1881
1882 const_local_iterator
1883 cbegin(size_type __n) const
1884 { return _M_h.cbegin(__n); }
1885 //@}
1886
1887 /**
1888 * @brief Returns a read/write iterator pointing to one past the last
1889 * bucket elements.
1890 * @param __n The bucket index.
1891 * @return A read/write local iterator.
1892 */
1893 local_iterator
1894 end(size_type __n)
1895 { return _M_h.end(__n); }
1896
1897 //@{
1898 /**
1899 * @brief Returns a read-only (constant) iterator pointing to one past
1900 * the last bucket elements.
1901 * @param __n The bucket index.
1902 * @return A read-only local iterator.
1903 */
1904 const_local_iterator
1905 end(size_type __n) const
1906 { return _M_h.end(__n); }
1907
1908 const_local_iterator
1909 cend(size_type __n) const
1910 { return _M_h.cend(__n); }
1911 //@}
1912
1913 // hash policy.
1914
1915 /// Returns the average number of elements per bucket.
1916 float
1917 load_factor() const noexcept
1918 { return _M_h.load_factor(); }
1919
1920 /// Returns a positive number that the %unordered_multimap tries to keep
1921 /// the load factor less than or equal to.
1922 float
1923 max_load_factor() const noexcept
1924 { return _M_h.max_load_factor(); }
1925
1926 /**
1927 * @brief Change the %unordered_multimap maximum load factor.
1928 * @param __z The new maximum load factor.
1929 */
1930 void
1931 max_load_factor(float __z)
1932 { _M_h.max_load_factor(__z); }
1933
1934 /**
1935 * @brief May rehash the %unordered_multimap.
1936 * @param __n The new number of buckets.
1937 *
1938 * Rehash will occur only if the new number of buckets respect the
1939 * %unordered_multimap maximum load factor.
1940 */
1941 void
1942 rehash(size_type __n)
1943 { _M_h.rehash(__n); }
1944
1945 /**
1946 * @brief Prepare the %unordered_multimap for a specified number of
1947 * elements.
1948 * @param __n Number of elements required.
1949 *
1950 * Same as rehash(ceil(n / max_load_factor())).
1951 */
1952 void
1953 reserve(size_type __n)
1954 { _M_h.reserve(__n); }
1955
1956 template<typename _Key1, typename _Tp1, typename _Hash1, typename _Pred1,
1957 typename _Alloc1>
1958 friend bool
1959 operator==(const unordered_multimap<_Key1, _Tp1,
1960 _Hash1, _Pred1, _Alloc1>&,
1961 const unordered_multimap<_Key1, _Tp1,
1962 _Hash1, _Pred1, _Alloc1>&);
1963 };
1964
1965#if __cpp_deduction_guides >= 201606
1966
1967 template<typename _InputIterator,
1968 typename _Hash = hash<__iter_key_t<_InputIterator>>,
1969 typename _Pred = equal_to<__iter_key_t<_InputIterator>>,
1970 typename _Allocator = allocator<__iter_to_alloc_t<_InputIterator>>,
1971 typename = _RequireInputIter<_InputIterator>,
1972 typename = _RequireAllocator<_Allocator>>
1973 unordered_multimap(_InputIterator, _InputIterator,
1974 unordered_multimap<int, int>::size_type = {},
1975 _Hash = _Hash(), _Pred = _Pred(),
1976 _Allocator = _Allocator())
1977 -> unordered_multimap<__iter_key_t<_InputIterator>,
1978 __iter_val_t<_InputIterator>, _Hash, _Pred,
1979 _Allocator>;
1980
1981 template<typename _Key, typename _Tp, typename _Hash = hash<_Key>,
1982 typename _Pred = equal_to<_Key>,
1983 typename _Allocator = allocator<pair<const _Key, _Tp>>,
1984 typename = _RequireAllocator<_Allocator>>
1985 unordered_multimap(initializer_list<pair<_Key, _Tp>>,
1986 unordered_multimap<int, int>::size_type = {},
1987 _Hash = _Hash(), _Pred = _Pred(),
1988 _Allocator = _Allocator())
1989 -> unordered_multimap<_Key, _Tp, _Hash, _Pred, _Allocator>;
1990
1991 template<typename _InputIterator, typename _Allocator,
1992 typename = _RequireInputIter<_InputIterator>,
1993 typename = _RequireAllocator<_Allocator>>
1994 unordered_multimap(_InputIterator, _InputIterator,
1995 unordered_multimap<int, int>::size_type, _Allocator)
1996 -> unordered_multimap<__iter_key_t<_InputIterator>,
1997 __iter_val_t<_InputIterator>,
1998 hash<__iter_key_t<_InputIterator>>,
1999 equal_to<__iter_key_t<_InputIterator>>, _Allocator>;
2000
2001 template<typename _InputIterator, typename _Allocator,
2002 typename = _RequireInputIter<_InputIterator>,
2003 typename = _RequireAllocator<_Allocator>>
2004 unordered_multimap(_InputIterator, _InputIterator, _Allocator)
2005 -> unordered_multimap<__iter_key_t<_InputIterator>,
2006 __iter_val_t<_InputIterator>,
2007 hash<__iter_key_t<_InputIterator>>,
2008 equal_to<__iter_key_t<_InputIterator>>, _Allocator>;
2009
2010 template<typename _InputIterator, typename _Hash, typename _Allocator,
2011 typename = _RequireInputIter<_InputIterator>,
2012 typename = _RequireAllocator<_Allocator>>
2013 unordered_multimap(_InputIterator, _InputIterator,
2014 unordered_multimap<int, int>::size_type, _Hash,
2015 _Allocator)
2016 -> unordered_multimap<__iter_key_t<_InputIterator>,
2017 __iter_val_t<_InputIterator>, _Hash,
2018 equal_to<__iter_key_t<_InputIterator>>, _Allocator>;
2019
2020 template<typename _Key, typename _Tp, typename _Allocator,
2021 typename = _RequireAllocator<_Allocator>>
2022 unordered_multimap(initializer_list<pair<_Key, _Tp>>,
2023 unordered_multimap<int, int>::size_type,
2024 _Allocator)
2025 -> unordered_multimap<_Key, _Tp, hash<_Key>, equal_to<_Key>, _Allocator>;
2026
2027 template<typename _Key, typename _Tp, typename _Allocator,
2028 typename = _RequireAllocator<_Allocator>>
2029 unordered_multimap(initializer_list<pair<_Key, _Tp>>, _Allocator)
2030 -> unordered_multimap<_Key, _Tp, hash<_Key>, equal_to<_Key>, _Allocator>;
2031
2032 template<typename _Key, typename _Tp, typename _Hash, typename _Allocator,
2033 typename = _RequireAllocator<_Allocator>>
2034 unordered_multimap(initializer_list<pair<_Key, _Tp>>,
2035 unordered_multimap<int, int>::size_type,
2036 _Hash, _Allocator)
2037 -> unordered_multimap<_Key, _Tp, _Hash, equal_to<_Key>, _Allocator>;
2038
2039#endif
2040
2041 template<class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
2042 inline void
2043 swap(unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
2044 unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
2045 noexcept(noexcept(__x.swap(__y)))
2046 { __x.swap(__y); }
2047
2048 template<class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
2049 inline void
2050 swap(unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
2051 unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
2052 noexcept(noexcept(__x.swap(__y)))
2053 { __x.swap(__y); }
2054
2055 template<class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
2056 inline bool
2057 operator==(const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
2058 const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
2059 { return __x._M_h._M_equal(__y._M_h); }
2060
2061 template<class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
2062 inline bool
2063 operator!=(const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
2064 const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
2065 { return !(__x == __y); }
2066
2067 template<class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
2068 inline bool
2069 operator==(const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
2070 const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
2071 { return __x._M_h._M_equal(__y._M_h); }
2072
2073 template<class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
2074 inline bool
2075 operator!=(const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
2076 const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
2077 { return !(__x == __y); }
2078
2079_GLIBCXX_END_NAMESPACE_CONTAINER
2080
2081#if __cplusplus > 201402L
2082 // Allow std::unordered_map access to internals of compatible maps.
2083 template<typename _Key, typename _Val, typename _Hash1, typename _Eq1,
2084 typename _Alloc, typename _Hash2, typename _Eq2>
2085 struct _Hash_merge_helper<
2086 _GLIBCXX_STD_C::unordered_map<_Key, _Val, _Hash1, _Eq1, _Alloc>,
2087 _Hash2, _Eq2>
2088 {
2089 private:
2090 template<typename... _Tp>
2091 using unordered_map = _GLIBCXX_STD_C::unordered_map<_Tp...>;
2092 template<typename... _Tp>
2093 using unordered_multimap = _GLIBCXX_STD_C::unordered_multimap<_Tp...>;
2094
2095 friend unordered_map<_Key, _Val, _Hash1, _Eq1, _Alloc>;
2096
2097 static auto&
2098 _S_get_table(unordered_map<_Key, _Val, _Hash2, _Eq2, _Alloc>& __map)
2099 { return __map._M_h; }
2100
2101 static auto&
2102 _S_get_table(unordered_multimap<_Key, _Val, _Hash2, _Eq2, _Alloc>& __map)
2103 { return __map._M_h; }
2104 };
2105
2106 // Allow std::unordered_multimap access to internals of compatible maps.
2107 template<typename _Key, typename _Val, typename _Hash1, typename _Eq1,
2108 typename _Alloc, typename _Hash2, typename _Eq2>
2109 struct _Hash_merge_helper<
2110 _GLIBCXX_STD_C::unordered_multimap<_Key, _Val, _Hash1, _Eq1, _Alloc>,
2111 _Hash2, _Eq2>
2112 {
2113 private:
2114 template<typename... _Tp>
2115 using unordered_map = _GLIBCXX_STD_C::unordered_map<_Tp...>;
2116 template<typename... _Tp>
2117 using unordered_multimap = _GLIBCXX_STD_C::unordered_multimap<_Tp...>;
2118
2119 friend unordered_multimap<_Key, _Val, _Hash1, _Eq1, _Alloc>;
2120
2121 static auto&
2122 _S_get_table(unordered_map<_Key, _Val, _Hash2, _Eq2, _Alloc>& __map)
2123 { return __map._M_h; }
2124
2125 static auto&
2126 _S_get_table(unordered_multimap<_Key, _Val, _Hash2, _Eq2, _Alloc>& __map)
2127 { return __map._M_h; }
2128 };
2129#endif // C++17
2130
2131_GLIBCXX_END_NAMESPACE_VERSION
2132} // namespace std
2133
2134#endif /* _UNORDERED_MAP_H */
2135