xref: /freebsd/contrib/llvm-project/libcxx/include/unordered_set (revision 5ca8e32633c4ffbbcd6762e5888b6a4ba0708c6c)
1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_UNORDERED_SET
11#define _LIBCPP_UNORDERED_SET
12
13/*
14
15    unordered_set synopsis
16
17#include <initializer_list>
18
19namespace std
20{
21
22template <class Value, class Hash = hash<Value>, class Pred = equal_to<Value>,
23          class Alloc = allocator<Value>>
24class unordered_set
25{
26public:
27    // types
28    typedef Value                                                      key_type;
29    typedef key_type                                                   value_type;
30    typedef Hash                                                       hasher;
31    typedef Pred                                                       key_equal;
32    typedef Alloc                                                      allocator_type;
33    typedef value_type&                                                reference;
34    typedef const value_type&                                          const_reference;
35    typedef typename allocator_traits<allocator_type>::pointer         pointer;
36    typedef typename allocator_traits<allocator_type>::const_pointer   const_pointer;
37    typedef typename allocator_traits<allocator_type>::size_type       size_type;
38    typedef typename allocator_traits<allocator_type>::difference_type difference_type;
39
40    typedef /unspecified/ iterator;
41    typedef /unspecified/ const_iterator;
42    typedef /unspecified/ local_iterator;
43    typedef /unspecified/ const_local_iterator;
44
45    typedef unspecified node_type unspecified;                            // C++17
46    typedef INSERT_RETURN_TYPE<iterator, node_type> insert_return_type;   // C++17
47
48    unordered_set()
49        noexcept(
50            is_nothrow_default_constructible<hasher>::value &&
51            is_nothrow_default_constructible<key_equal>::value &&
52            is_nothrow_default_constructible<allocator_type>::value);
53    explicit unordered_set(size_type n, const hasher& hf = hasher(),
54                           const key_equal& eql = key_equal(),
55                           const allocator_type& a = allocator_type());
56    template <class InputIterator>
57        unordered_set(InputIterator f, InputIterator l,
58                      size_type n = 0, const hasher& hf = hasher(),
59                      const key_equal& eql = key_equal(),
60                      const allocator_type& a = allocator_type());
61    template<container-compatible-range<value_type> R>
62      unordered_set(from_range_t, R&& rg, size_type n = see below,
63        const hasher& hf = hasher(), const key_equal& eql = key_equal(),
64        const allocator_type& a = allocator_type()); // C++23
65    explicit unordered_set(const allocator_type&);
66    unordered_set(const unordered_set&);
67    unordered_set(const unordered_set&, const Allocator&);
68    unordered_set(unordered_set&&)
69        noexcept(
70            is_nothrow_move_constructible<hasher>::value &&
71            is_nothrow_move_constructible<key_equal>::value &&
72            is_nothrow_move_constructible<allocator_type>::value);
73    unordered_set(unordered_set&&, const Allocator&);
74    unordered_set(initializer_list<value_type>, size_type n = 0,
75                  const hasher& hf = hasher(), const key_equal& eql = key_equal(),
76                  const allocator_type& a = allocator_type());
77    unordered_set(size_type n, const allocator_type& a); // C++14
78    unordered_set(size_type n, const hasher& hf, const allocator_type& a); // C++14
79    template <class InputIterator>
80      unordered_set(InputIterator f, InputIterator l, size_type n, const allocator_type& a); // C++14
81    template <class InputIterator>
82      unordered_set(InputIterator f, InputIterator l, size_type n,
83                    const hasher& hf,  const allocator_type& a); // C++14
84    template<container-compatible-range<value_type> R>
85      unordered_set(from_range_t, R&& rg, size_type n, const allocator_type& a)
86        : unordered_set(from_range, std::forward<R>(rg), n, hasher(), key_equal(), a) { } // C++23
87    template<container-compatible-range<value_type> R>
88      unordered_set(from_range_t, R&& rg, size_type n, const hasher& hf, const allocator_type& a)
89        : unordered_set(from_range, std::forward<R>(rg), n, hf, key_equal(), a) { }       // C++23
90    unordered_set(initializer_list<value_type> il, size_type n, const allocator_type& a); // C++14
91    unordered_set(initializer_list<value_type> il, size_type n,
92                  const hasher& hf,  const allocator_type& a); // C++14
93    ~unordered_set();
94    unordered_set& operator=(const unordered_set&);
95    unordered_set& operator=(unordered_set&&)
96        noexcept(
97            allocator_type::propagate_on_container_move_assignment::value &&
98            is_nothrow_move_assignable<allocator_type>::value &&
99            is_nothrow_move_assignable<hasher>::value &&
100            is_nothrow_move_assignable<key_equal>::value);
101    unordered_set& operator=(initializer_list<value_type>);
102
103    allocator_type get_allocator() const noexcept;
104
105    bool      empty() const noexcept;
106    size_type size() const noexcept;
107    size_type max_size() const noexcept;
108
109    iterator       begin() noexcept;
110    iterator       end() noexcept;
111    const_iterator begin()  const noexcept;
112    const_iterator end()    const noexcept;
113    const_iterator cbegin() const noexcept;
114    const_iterator cend()   const noexcept;
115
116    template <class... Args>
117        pair<iterator, bool> emplace(Args&&... args);
118    template <class... Args>
119        iterator emplace_hint(const_iterator position, Args&&... args);
120    pair<iterator, bool> insert(const value_type& obj);
121    pair<iterator, bool> insert(value_type&& obj);
122    iterator insert(const_iterator hint, const value_type& obj);
123    iterator insert(const_iterator hint, value_type&& obj);
124    template <class InputIterator>
125        void insert(InputIterator first, InputIterator last);
126    template<container-compatible-range<value_type> R>
127      void insert_range(R&& rg);                                      // C++23
128    void insert(initializer_list<value_type>);
129
130    node_type extract(const_iterator position);                       // C++17
131    node_type extract(const key_type& x);                             // C++17
132    insert_return_type insert(node_type&& nh);                        // C++17
133    iterator           insert(const_iterator hint, node_type&& nh);   // C++17
134
135    iterator erase(const_iterator position);
136    iterator erase(iterator position);  // C++14
137    size_type erase(const key_type& k);
138    iterator erase(const_iterator first, const_iterator last);
139    void clear() noexcept;
140
141    template<class H2, class P2>
142      void merge(unordered_set<Key, H2, P2, Allocator>& source);         // C++17
143    template<class H2, class P2>
144      void merge(unordered_set<Key, H2, P2, Allocator>&& source);        // C++17
145    template<class H2, class P2>
146      void merge(unordered_multiset<Key, H2, P2, Allocator>& source);    // C++17
147    template<class H2, class P2>
148      void merge(unordered_multiset<Key, H2, P2, Allocator>&& source);   // C++17
149
150    void swap(unordered_set&)
151       noexcept(allocator_traits<Allocator>::is_always_equal::value &&
152                 noexcept(swap(declval<hasher&>(), declval<hasher&>())) &&
153                 noexcept(swap(declval<key_equal&>(), declval<key_equal&>()))); // C++17
154
155    hasher hash_function() const;
156    key_equal key_eq() const;
157
158    iterator       find(const key_type& k);
159    const_iterator find(const key_type& k) const;
160    template<typename K>
161        iterator find(const K& x);              // C++20
162    template<typename K>
163        const_iterator find(const K& x) const;  // C++20
164    size_type count(const key_type& k) const;
165    template<typename K>
166        size_type count(const K& k) const; // C++20
167    bool contains(const key_type& k) const; // C++20
168    template<typename K>
169        bool contains(const K& k) const; // C++20
170    pair<iterator, iterator>             equal_range(const key_type& k);
171    pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
172    template<typename K>
173        pair<iterator, iterator>             equal_range(const K& k); // C++20
174    template<typename K>
175        pair<const_iterator, const_iterator> equal_range(const K& k) const; // C++20
176
177    size_type bucket_count() const noexcept;
178    size_type max_bucket_count() const noexcept;
179
180    size_type bucket_size(size_type n) const;
181    size_type bucket(const key_type& k) const;
182
183    local_iterator       begin(size_type n);
184    local_iterator       end(size_type n);
185    const_local_iterator begin(size_type n) const;
186    const_local_iterator end(size_type n) const;
187    const_local_iterator cbegin(size_type n) const;
188    const_local_iterator cend(size_type n) const;
189
190    float load_factor() const noexcept;
191    float max_load_factor() const noexcept;
192    void max_load_factor(float z);
193    void rehash(size_type n);
194    void reserve(size_type n);
195};
196
197template<class InputIterator,
198    class Hash = hash<typename iterator_traits<InputIterator>::value_type>,
199    class Pred = equal_to<typename iterator_traits<InputIterator>::value_type>,
200    class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
201unordered_set(InputIterator, InputIterator, typename see below::size_type = see below,
202    Hash = Hash(), Pred = Pred(), Allocator = Allocator())
203  -> unordered_set<typename iterator_traits<InputIterator>::value_type,
204        Hash, Pred, Allocator>; // C++17
205
206template<ranges::input_range R,
207         class Hash = hash<ranges::range_value_t<R>>,
208         class Pred = equal_to<ranges::range_value_t<R>>,
209         class Allocator = allocator<ranges::range_value_t<R>>>
210  unordered_set(from_range_t, R&&, typename see below::size_type = see below, Hash = Hash(), Pred = Pred(), Allocator = Allocator())
211    -> unordered_set<ranges::range_value_t<R>, Hash, Pred, Allocator>; // C++23
212
213template<class T, class Hash = hash<T>,
214          class Pred = equal_to<T>, class Allocator = allocator<T>>
215unordered_set(initializer_list<T>, typename see below::size_type = see below,
216    Hash = Hash(), Pred = Pred(), Allocator = Allocator())
217  -> unordered_set<T, Hash, Pred, Allocator>; // C++17
218
219template<class InputIterator,  class Allocator>
220unordered_set(InputIterator, InputIterator, typename see below::size_type, Allocator)
221  -> unordered_set<typename iterator_traits<InputIterator>::value_type,
222        hash<typename iterator_traits<InputIterator>::value_type>,
223        equal_to<typename iterator_traits<InputIterator>::value_type>,
224        Allocator>; // C++17
225
226template<class InputIterator, class Hash, class Allocator>
227unordered_set(InputIterator, InputIterator, typename see below::size_type,
228    Hash, Allocator)
229  -> unordered_set<typename iterator_traits<InputIterator>::value_type, Hash,
230        equal_to<typename iterator_traits<InputIterator>::value_type>,
231        Allocator>; // C++17
232
233template<ranges::input_range R, class Allocator>
234  unordered_set(from_range_t, R&&, typename see below::size_type, Allocator)
235    -> unordered_set<ranges::range_value_t<R>, hash<ranges::range_value_t<R>>,
236                      equal_to<ranges::range_value_t<R>>, Allocator>; // C++23
237
238template<ranges::input_range R, class Allocator>
239  unordered_set(from_range_t, R&&, Allocator)
240    -> unordered_set<ranges::range_value_t<R>, hash<ranges::range_value_t<R>>,
241                      equal_to<ranges::range_value_t<R>>, Allocator>; // C++23
242
243template<ranges::input_range R, class Hash, class Allocator>
244  unordered_set(from_range_t, R&&, typename see below::size_type, Hash, Allocator)
245    -> unordered_set<ranges::range_value_t<R>, Hash,
246                      equal_to<ranges::range_value_t<R>>, Allocator>; // C++23
247
248template<class T, class Allocator>
249unordered_set(initializer_list<T>, typename see below::size_type, Allocator)
250  -> unordered_set<T, hash<T>, equal_to<T>, Allocator>; // C++17
251
252template<class T, class Hash, class Allocator>
253unordered_set(initializer_list<T>, typename see below::size_type, Hash, Allocator)
254  -> unordered_set<T, Hash, equal_to<T>, Allocator>; // C++17
255
256template <class Value, class Hash, class Pred, class Alloc>
257    void swap(unordered_set<Value, Hash, Pred, Alloc>& x,
258              unordered_set<Value, Hash, Pred, Alloc>& y)
259              noexcept(noexcept(x.swap(y)));
260
261template <class Value, class Hash, class Pred, class Alloc>
262    bool
263    operator==(const unordered_set<Value, Hash, Pred, Alloc>& x,
264               const unordered_set<Value, Hash, Pred, Alloc>& y);
265
266template <class Value, class Hash, class Pred, class Alloc>
267    bool
268    operator!=(const unordered_set<Value, Hash, Pred, Alloc>& x,
269               const unordered_set<Value, Hash, Pred, Alloc>& y); // removed in C++20
270
271template <class Value, class Hash = hash<Value>, class Pred = equal_to<Value>,
272          class Alloc = allocator<Value>>
273class unordered_multiset
274{
275public:
276    // types
277    typedef Value                                                      key_type;
278    typedef key_type                                                   value_type;
279    typedef Hash                                                       hasher;
280    typedef Pred                                                       key_equal;
281    typedef Alloc                                                      allocator_type;
282    typedef value_type&                                                reference;
283    typedef const value_type&                                          const_reference;
284    typedef typename allocator_traits<allocator_type>::pointer         pointer;
285    typedef typename allocator_traits<allocator_type>::const_pointer   const_pointer;
286    typedef typename allocator_traits<allocator_type>::size_type       size_type;
287    typedef typename allocator_traits<allocator_type>::difference_type difference_type;
288
289    typedef /unspecified/ iterator;
290    typedef /unspecified/ const_iterator;
291    typedef /unspecified/ local_iterator;
292    typedef /unspecified/ const_local_iterator;
293
294    typedef unspecified node_type unspecified;   // C++17
295
296    unordered_multiset()
297        noexcept(
298            is_nothrow_default_constructible<hasher>::value &&
299            is_nothrow_default_constructible<key_equal>::value &&
300            is_nothrow_default_constructible<allocator_type>::value);
301    explicit unordered_multiset(size_type n, const hasher& hf = hasher(),
302                           const key_equal& eql = key_equal(),
303                           const allocator_type& a = allocator_type());
304    template <class InputIterator>
305        unordered_multiset(InputIterator f, InputIterator l,
306                      size_type n = 0, const hasher& hf = hasher(),
307                      const key_equal& eql = key_equal(),
308                      const allocator_type& a = allocator_type());
309    template<container-compatible-range<value_type> R>
310      unordered_multiset(from_range_t, R&& rg, size_type n = see below,
311        const hasher& hf = hasher(), const key_equal& eql = key_equal(),
312        const allocator_type& a = allocator_type()); // C++23
313    explicit unordered_multiset(const allocator_type&);
314    unordered_multiset(const unordered_multiset&);
315    unordered_multiset(const unordered_multiset&, const Allocator&);
316    unordered_multiset(unordered_multiset&&)
317        noexcept(
318            is_nothrow_move_constructible<hasher>::value &&
319            is_nothrow_move_constructible<key_equal>::value &&
320            is_nothrow_move_constructible<allocator_type>::value);
321    unordered_multiset(unordered_multiset&&, const Allocator&);
322    unordered_multiset(initializer_list<value_type>, size_type n = /see below/,
323                  const hasher& hf = hasher(), const key_equal& eql = key_equal(),
324                  const allocator_type& a = allocator_type());
325    unordered_multiset(size_type n, const allocator_type& a); // C++14
326    unordered_multiset(size_type n, const hasher& hf, const allocator_type& a); // C++14
327    template <class InputIterator>
328      unordered_multiset(InputIterator f, InputIterator l, size_type n, const allocator_type& a); // C++14
329    template <class InputIterator>
330      unordered_multiset(InputIterator f, InputIterator l, size_type n,
331                         const hasher& hf, const allocator_type& a); // C++14
332    template<container-compatible-range<value_type> R>
333      unordered_multiset(from_range_t, R&& rg, size_type n, const allocator_type& a)
334        : unordered_multiset(from_range, std::forward<R>(rg), n, hasher(), key_equal(), a) { } // C++23
335    template<container-compatible-range<value_type> R>
336      unordered_multiset(from_range_t, R&& rg, size_type n, const hasher& hf, const allocator_type& a)
337        : unordered_multiset(from_range, std::forward<R>(rg), n, hf, key_equal(), a) { }       // C++23
338    unordered_multiset(initializer_list<value_type> il, size_type n, const allocator_type& a); // C++14
339    unordered_multiset(initializer_list<value_type> il, size_type n,
340                       const hasher& hf,  const allocator_type& a); // C++14
341    ~unordered_multiset();
342    unordered_multiset& operator=(const unordered_multiset&);
343    unordered_multiset& operator=(unordered_multiset&&)
344        noexcept(
345            allocator_type::propagate_on_container_move_assignment::value &&
346            is_nothrow_move_assignable<allocator_type>::value &&
347            is_nothrow_move_assignable<hasher>::value &&
348            is_nothrow_move_assignable<key_equal>::value);
349    unordered_multiset& operator=(initializer_list<value_type>);
350
351    allocator_type get_allocator() const noexcept;
352
353    bool      empty() const noexcept;
354    size_type size() const noexcept;
355    size_type max_size() const noexcept;
356
357    iterator       begin() noexcept;
358    iterator       end() noexcept;
359    const_iterator begin()  const noexcept;
360    const_iterator end()    const noexcept;
361    const_iterator cbegin() const noexcept;
362    const_iterator cend()   const noexcept;
363
364    template <class... Args>
365        iterator emplace(Args&&... args);
366    template <class... Args>
367        iterator emplace_hint(const_iterator position, Args&&... args);
368    iterator insert(const value_type& obj);
369    iterator insert(value_type&& obj);
370    iterator insert(const_iterator hint, const value_type& obj);
371    iterator insert(const_iterator hint, value_type&& obj);
372    template <class InputIterator>
373        void insert(InputIterator first, InputIterator last);
374    template<container-compatible-range<value_type> R>
375      void insert_range(R&& rg);                            // C++23
376    void insert(initializer_list<value_type>);
377
378    node_type extract(const_iterator position);             // C++17
379    node_type extract(const key_type& x);                   // C++17
380    iterator insert(node_type&& nh);                        // C++17
381    iterator insert(const_iterator hint, node_type&& nh);   // C++17
382
383    iterator erase(const_iterator position);
384    iterator erase(iterator position);  // C++14
385    size_type erase(const key_type& k);
386    iterator erase(const_iterator first, const_iterator last);
387    void clear() noexcept;
388
389    template<class H2, class P2>
390      void merge(unordered_multiset<Key, H2, P2, Allocator>& source);    // C++17
391    template<class H2, class P2>
392      void merge(unordered_multiset<Key, H2, P2, Allocator>&& source);   // C++17
393    template<class H2, class P2>
394      void merge(unordered_set<Key, H2, P2, Allocator>& source);         // C++17
395    template<class H2, class P2>
396      void merge(unordered_set<Key, H2, P2, Allocator>&& source);        // C++17
397
398    void swap(unordered_multiset&)
399       noexcept(allocator_traits<Allocator>::is_always_equal::value &&
400                 noexcept(swap(declval<hasher&>(), declval<hasher&>())) &&
401                 noexcept(swap(declval<key_equal&>(), declval<key_equal&>()))); // C++17
402
403    hasher hash_function() const;
404    key_equal key_eq() const;
405
406    iterator       find(const key_type& k);
407    const_iterator find(const key_type& k) const;
408    template<typename K>
409        iterator find(const K& x);              // C++20
410    template<typename K>
411        const_iterator find(const K& x) const;  // C++20
412    size_type count(const key_type& k) const;
413    template<typename K>
414        size_type count(const K& k) const; // C++20
415    bool contains(const key_type& k) const; // C++20
416    template<typename K>
417        bool contains(const K& k) const; // C++20
418    pair<iterator, iterator>             equal_range(const key_type& k);
419    pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
420    template<typename K>
421        pair<iterator, iterator>             equal_range(const K& k); // C++20
422    template<typename K>
423        pair<const_iterator, const_iterator> equal_range(const K& k) const; // C++20
424
425    size_type bucket_count() const noexcept;
426    size_type max_bucket_count() const noexcept;
427
428    size_type bucket_size(size_type n) const;
429    size_type bucket(const key_type& k) const;
430
431    local_iterator       begin(size_type n);
432    local_iterator       end(size_type n);
433    const_local_iterator begin(size_type n) const;
434    const_local_iterator end(size_type n) const;
435    const_local_iterator cbegin(size_type n) const;
436    const_local_iterator cend(size_type n) const;
437
438    float load_factor() const noexcept;
439    float max_load_factor() const noexcept;
440    void max_load_factor(float z);
441    void rehash(size_type n);
442    void reserve(size_type n);
443};
444
445template<class InputIterator,
446    class Hash = hash<typename iterator_traits<InputIterator>::value_type>,
447    class Pred = equal_to<typename iterator_traits<InputIterator>::value_type>,
448    class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
449unordered_multiset(InputIterator, InputIterator, see below::size_type = see below,
450    Hash = Hash(), Pred = Pred(), Allocator = Allocator())
451  -> unordered_multiset<typename iterator_traits<InputIterator>::value_type,
452        Hash, Pred, Allocator>; // C++17
453
454template<ranges::input_range R,
455         class Hash = hash<ranges::range_value_t<R>>,
456         class Pred = equal_to<ranges::range_value_t<R>>,
457         class Allocator = allocator<ranges::range_value_t<R>>>
458  unordered_multiset(from_range_t, R&&, typename see below::size_type = see below, Hash = Hash(), Pred = Pred(), Allocator = Allocator())
459    -> unordered_multiset<ranges::range_value_t<R>, Hash, Pred, Allocator>; // C++23
460
461template<class T, class Hash = hash<T>,
462          class Pred = equal_to<T>, class Allocator = allocator<T>>
463unordered_multiset(initializer_list<T>, typename see below::size_type = see below,
464    Hash = Hash(), Pred = Pred(), Allocator = Allocator())
465  -> unordered_multiset<T, Hash, Pred, Allocator>; // C++17
466
467template<class InputIterator,  class Allocator>
468unordered_multiset(InputIterator, InputIterator, typename see below::size_type, Allocator)
469  -> unordered_multiset<typename iterator_traits<InputIterator>::value_type,
470        hash<typename iterator_traits<InputIterator>::value_type>,
471        equal_to<typename iterator_traits<InputIterator>::value_type>,
472        Allocator>; // C++17
473
474template<class InputIterator,  class Hash, class Allocator>
475unordered_multiset(InputIterator, InputIterator, typename see below::size_type,
476    Hash, Allocator)
477  -> unordered_multiset<typename iterator_traits<InputIterator>::value_type, Hash,
478        equal_to<typename iterator_traits<InputIterator>::value_type>, Allocator>; // C++17
479
480template<ranges::input_range R, class Allocator>
481  unordered_multiset(from_range_t, R&&, typename see below::size_type, Allocator)
482    -> unordered_multiset<ranges::range_value_t<R>, hash<ranges::range_value_t<R>>,
483                      equal_to<ranges::range_value_t<R>>, Allocator>; // C++23
484
485template<ranges::input_range R, class Allocator>
486  unordered_multiset(from_range_t, R&&, Allocator)
487    -> unordered_multiset<ranges::range_value_t<R>, hash<ranges::range_value_t<R>>,
488                      equal_to<ranges::range_value_t<R>>, Allocator>; // C++23
489
490template<ranges::input_range R, class Hash, class Allocator>
491  unordered_multiset(from_range_t, R&&, typename see below::size_type, Hash, Allocator)
492    -> unordered_multiset<ranges::range_value_t<R>, Hash,
493                      equal_to<ranges::range_value_t<R>>, Allocator>; // C++23
494
495template<class T, class Allocator>
496unordered_multiset(initializer_list<T>, typename see below::size_type, Allocator)
497  -> unordered_multiset<T, hash<T>, equal_to<T>, Allocator>; // C++17
498
499template<class T, class Hash, class Allocator>
500unordered_multiset(initializer_list<T>, typename see below::size_type, Hash, Allocator)
501  -> unordered_multiset<T, Hash, equal_to<T>, Allocator>; // C++17
502
503template <class Value, class Hash, class Pred, class Alloc>
504    void swap(unordered_multiset<Value, Hash, Pred, Alloc>& x,
505              unordered_multiset<Value, Hash, Pred, Alloc>& y)
506              noexcept(noexcept(x.swap(y)));
507
508template <class K, class T, class H, class P, class A, class Predicate>
509    typename unordered_set<K, T, H, P, A>::size_type
510    erase_if(unordered_set<K, T, H, P, A>& c, Predicate pred);       // C++20
511
512template <class K, class T, class H, class P, class A, class Predicate>
513    typename unordered_multiset<K, T, H, P, A>::size_type
514    erase_if(unordered_multiset<K, T, H, P, A>& c, Predicate pred);  // C++20
515
516
517template <class Value, class Hash, class Pred, class Alloc>
518    bool
519    operator==(const unordered_multiset<Value, Hash, Pred, Alloc>& x,
520               const unordered_multiset<Value, Hash, Pred, Alloc>& y);
521
522template <class Value, class Hash, class Pred, class Alloc>
523    bool
524    operator!=(const unordered_multiset<Value, Hash, Pred, Alloc>& x,
525               const unordered_multiset<Value, Hash, Pred, Alloc>& y); // removed in C++20
526}  // std
527
528*/
529
530#include <__algorithm/is_permutation.h>
531#include <__assert> // all public C++ headers provide the assertion handler
532#include <__availability>
533#include <__config>
534#include <__functional/is_transparent.h>
535#include <__functional/operations.h>
536#include <__hash_table>
537#include <__iterator/distance.h>
538#include <__iterator/erase_if_container.h>
539#include <__iterator/iterator_traits.h>
540#include <__iterator/ranges_iterator_traits.h>
541#include <__memory/addressof.h>
542#include <__memory/allocator.h>
543#include <__memory_resource/polymorphic_allocator.h>
544#include <__node_handle>
545#include <__ranges/concepts.h>
546#include <__ranges/container_compatible_range.h>
547#include <__ranges/from_range.h>
548#include <__type_traits/is_allocator.h>
549#include <__utility/forward.h>
550#include <version>
551
552// standard-mandated includes
553
554// [iterator.range]
555#include <__iterator/access.h>
556#include <__iterator/data.h>
557#include <__iterator/empty.h>
558#include <__iterator/reverse_access.h>
559#include <__iterator/size.h>
560
561// [unord.set.syn]
562#include <compare>
563#include <initializer_list>
564
565#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
566#  pragma GCC system_header
567#endif
568
569_LIBCPP_BEGIN_NAMESPACE_STD
570
571template <class _Value, class _Hash, class _Pred, class _Alloc>
572class unordered_multiset;
573
574template <class _Value, class _Hash = hash<_Value>, class _Pred = equal_to<_Value>,
575          class _Alloc = allocator<_Value> >
576class _LIBCPP_TEMPLATE_VIS unordered_set
577{
578public:
579    // types
580    typedef _Value                                                     key_type;
581    typedef key_type                                                   value_type;
582    typedef __type_identity_t<_Hash>                                   hasher;
583    typedef __type_identity_t<_Pred>                                   key_equal;
584    typedef __type_identity_t<_Alloc>                                  allocator_type;
585    typedef value_type&                                                reference;
586    typedef const value_type&                                          const_reference;
587    static_assert((is_same<value_type, typename allocator_type::value_type>::value),
588                  "Allocator::value_type must be same type as value_type");
589
590    static_assert(is_same<allocator_type, __rebind_alloc<allocator_traits<allocator_type>, value_type> >::value,
591                  "[allocator.requirements] states that rebinding an allocator to the same type should result in the "
592                  "original allocator");
593
594  private:
595    typedef __hash_table<value_type, hasher, key_equal, allocator_type> __table;
596
597    __table __table_;
598
599public:
600    typedef typename __table::pointer         pointer;
601    typedef typename __table::const_pointer   const_pointer;
602    typedef typename __table::size_type       size_type;
603    typedef typename __table::difference_type difference_type;
604
605    typedef typename __table::const_iterator       iterator;
606    typedef typename __table::const_iterator       const_iterator;
607    typedef typename __table::const_local_iterator local_iterator;
608    typedef typename __table::const_local_iterator const_local_iterator;
609
610#if _LIBCPP_STD_VER >= 17
611    typedef __set_node_handle<typename __table::__node, allocator_type> node_type;
612    typedef __insert_return_type<iterator, node_type> insert_return_type;
613#endif
614
615    template <class _Value2, class _Hash2, class _Pred2, class _Alloc2>
616        friend class _LIBCPP_TEMPLATE_VIS unordered_set;
617    template <class _Value2, class _Hash2, class _Pred2, class _Alloc2>
618        friend class _LIBCPP_TEMPLATE_VIS unordered_multiset;
619
620    _LIBCPP_INLINE_VISIBILITY
621    unordered_set()
622        _NOEXCEPT_(is_nothrow_default_constructible<__table>::value)
623    {
624    }
625    explicit _LIBCPP_HIDE_FROM_ABI unordered_set(size_type __n, const hasher& __hf = hasher(),
626                           const key_equal& __eql = key_equal());
627#if _LIBCPP_STD_VER >= 14
628    inline _LIBCPP_INLINE_VISIBILITY
629    unordered_set(size_type __n, const allocator_type& __a)
630        : unordered_set(__n, hasher(), key_equal(), __a) {}
631    inline _LIBCPP_INLINE_VISIBILITY
632    unordered_set(size_type __n, const hasher& __hf, const allocator_type& __a)
633        : unordered_set(__n, __hf, key_equal(), __a) {}
634#endif
635    _LIBCPP_HIDE_FROM_ABI unordered_set(size_type __n, const hasher& __hf, const key_equal& __eql,
636                  const allocator_type& __a);
637    template <class _InputIterator>
638    _LIBCPP_HIDE_FROM_ABI unordered_set(_InputIterator __first, _InputIterator __last);
639    template <class _InputIterator>
640    _LIBCPP_HIDE_FROM_ABI unordered_set(_InputIterator __first, _InputIterator __last,
641                      size_type __n, const hasher& __hf = hasher(),
642                      const key_equal& __eql = key_equal());
643    template <class _InputIterator>
644    _LIBCPP_HIDE_FROM_ABI unordered_set(_InputIterator __first, _InputIterator __last,
645                      size_type __n, const hasher& __hf, const key_equal& __eql,
646                      const allocator_type& __a);
647
648#if _LIBCPP_STD_VER >= 23
649    template <_ContainerCompatibleRange<value_type> _Range>
650    _LIBCPP_HIDE_FROM_ABI
651    unordered_set(from_range_t, _Range&& __range, size_type __n = /*implementation-defined*/0,
652                  const hasher& __hf = hasher(), const key_equal& __eql = key_equal(),
653                  const allocator_type& __a = allocator_type())
654    : __table_(__hf, __eql, __a) {
655      if (__n > 0) {
656        __table_.__rehash_unique(__n);
657      }
658      insert_range(std::forward<_Range>(__range));
659    }
660#endif
661
662#if _LIBCPP_STD_VER >= 14
663    template <class _InputIterator>
664    inline _LIBCPP_INLINE_VISIBILITY
665        unordered_set(_InputIterator __first, _InputIterator __last,
666                    size_type __n, const allocator_type& __a)
667            : unordered_set(__first, __last, __n, hasher(), key_equal(), __a) {}
668    template <class _InputIterator>
669    _LIBCPP_HIDE_FROM_ABI unordered_set(_InputIterator __first, _InputIterator __last,
670                      size_type __n, const hasher& __hf, const allocator_type& __a)
671            : unordered_set(__first, __last, __n, __hf, key_equal(), __a) {}
672#endif
673
674#if _LIBCPP_STD_VER >= 23
675    template <_ContainerCompatibleRange<value_type> _Range>
676    _LIBCPP_HIDE_FROM_ABI
677    unordered_set(from_range_t, _Range&& __range, size_type __n, const allocator_type& __a)
678        : unordered_set(from_range, std::forward<_Range>(__range), __n, hasher(), key_equal(), __a) {}
679
680    template <_ContainerCompatibleRange<value_type> _Range>
681    _LIBCPP_HIDE_FROM_ABI
682    unordered_set(from_range_t, _Range&& __range, size_type __n, const hasher& __hf, const allocator_type& __a)
683        : unordered_set(from_range, std::forward<_Range>(__range), __n, __hf, key_equal(), __a) {}
684#endif
685
686    _LIBCPP_INLINE_VISIBILITY
687    explicit unordered_set(const allocator_type& __a);
688    _LIBCPP_HIDE_FROM_ABI unordered_set(const unordered_set& __u);
689    _LIBCPP_HIDE_FROM_ABI unordered_set(const unordered_set& __u, const allocator_type& __a);
690#ifndef _LIBCPP_CXX03_LANG
691    _LIBCPP_INLINE_VISIBILITY
692    unordered_set(unordered_set&& __u)
693        _NOEXCEPT_(is_nothrow_move_constructible<__table>::value);
694    _LIBCPP_HIDE_FROM_ABI unordered_set(unordered_set&& __u, const allocator_type& __a);
695    _LIBCPP_HIDE_FROM_ABI unordered_set(initializer_list<value_type> __il);
696    _LIBCPP_HIDE_FROM_ABI unordered_set(initializer_list<value_type> __il, size_type __n,
697                  const hasher& __hf = hasher(),
698                  const key_equal& __eql = key_equal());
699    _LIBCPP_HIDE_FROM_ABI unordered_set(initializer_list<value_type> __il, size_type __n,
700                  const hasher& __hf, const key_equal& __eql,
701                  const allocator_type& __a);
702#if _LIBCPP_STD_VER >= 14
703    inline _LIBCPP_INLINE_VISIBILITY
704    unordered_set(initializer_list<value_type> __il, size_type __n,
705                                                      const allocator_type& __a)
706        : unordered_set(__il, __n, hasher(), key_equal(), __a) {}
707    inline _LIBCPP_INLINE_VISIBILITY
708    unordered_set(initializer_list<value_type> __il, size_type __n,
709                                  const hasher& __hf, const allocator_type& __a)
710        : unordered_set(__il, __n, __hf, key_equal(), __a) {}
711#endif
712#endif // _LIBCPP_CXX03_LANG
713    _LIBCPP_INLINE_VISIBILITY
714    ~unordered_set() {
715        static_assert(sizeof(std::__diagnose_unordered_container_requirements<_Value, _Hash, _Pred>(0)), "");
716    }
717
718    _LIBCPP_INLINE_VISIBILITY
719    unordered_set& operator=(const unordered_set& __u)
720    {
721        __table_ = __u.__table_;
722        return *this;
723    }
724#ifndef _LIBCPP_CXX03_LANG
725    _LIBCPP_INLINE_VISIBILITY
726    unordered_set& operator=(unordered_set&& __u)
727        _NOEXCEPT_(is_nothrow_move_assignable<__table>::value);
728    _LIBCPP_INLINE_VISIBILITY
729    unordered_set& operator=(initializer_list<value_type> __il);
730#endif // _LIBCPP_CXX03_LANG
731
732    _LIBCPP_INLINE_VISIBILITY
733    allocator_type get_allocator() const _NOEXCEPT
734        {return allocator_type(__table_.__node_alloc());}
735
736    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
737    bool      empty() const _NOEXCEPT {return __table_.size() == 0;}
738    _LIBCPP_INLINE_VISIBILITY
739    size_type size() const _NOEXCEPT  {return __table_.size();}
740    _LIBCPP_INLINE_VISIBILITY
741    size_type max_size() const _NOEXCEPT {return __table_.max_size();}
742
743    _LIBCPP_INLINE_VISIBILITY
744    iterator       begin() _NOEXCEPT        {return __table_.begin();}
745    _LIBCPP_INLINE_VISIBILITY
746    iterator       end() _NOEXCEPT          {return __table_.end();}
747    _LIBCPP_INLINE_VISIBILITY
748    const_iterator begin()  const _NOEXCEPT {return __table_.begin();}
749    _LIBCPP_INLINE_VISIBILITY
750    const_iterator end()    const _NOEXCEPT {return __table_.end();}
751    _LIBCPP_INLINE_VISIBILITY
752    const_iterator cbegin() const _NOEXCEPT {return __table_.begin();}
753    _LIBCPP_INLINE_VISIBILITY
754    const_iterator cend()   const _NOEXCEPT {return __table_.end();}
755
756#ifndef _LIBCPP_CXX03_LANG
757    template <class... _Args>
758        _LIBCPP_INLINE_VISIBILITY
759        pair<iterator, bool> emplace(_Args&&... __args)
760            {return __table_.__emplace_unique(_VSTD::forward<_Args>(__args)...);}
761    template <class... _Args>
762    _LIBCPP_INLINE_VISIBILITY
763    iterator emplace_hint(const_iterator, _Args&&... __args) {
764        return __table_.__emplace_unique(std::forward<_Args>(__args)...).first;
765    }
766
767    _LIBCPP_INLINE_VISIBILITY
768    pair<iterator, bool> insert(value_type&& __x)
769        {return __table_.__insert_unique(_VSTD::move(__x));}
770    _LIBCPP_INLINE_VISIBILITY
771    iterator insert(const_iterator, value_type&& __x) {
772        return insert(std::move(__x)).first;
773    }
774
775    _LIBCPP_INLINE_VISIBILITY
776    void insert(initializer_list<value_type> __il)
777        {insert(__il.begin(), __il.end());}
778#endif // _LIBCPP_CXX03_LANG
779    _LIBCPP_INLINE_VISIBILITY
780    pair<iterator, bool> insert(const value_type& __x)
781        {return __table_.__insert_unique(__x);}
782
783    _LIBCPP_INLINE_VISIBILITY
784    iterator insert(const_iterator, const value_type& __x) {
785        return insert(__x).first;
786    }
787    template <class _InputIterator>
788        _LIBCPP_INLINE_VISIBILITY
789        void insert(_InputIterator __first, _InputIterator __last);
790
791#if _LIBCPP_STD_VER >= 23
792    template <_ContainerCompatibleRange<value_type> _Range>
793    _LIBCPP_HIDE_FROM_ABI
794    void insert_range(_Range&& __range) {
795      for (auto&& __element : __range) {
796        __table_.__insert_unique(std::forward<decltype(__element)>(__element));
797      }
798    }
799#endif
800
801    _LIBCPP_INLINE_VISIBILITY
802    iterator erase(const_iterator __p) {return __table_.erase(__p);}
803    _LIBCPP_INLINE_VISIBILITY
804    size_type erase(const key_type& __k) {return __table_.__erase_unique(__k);}
805    _LIBCPP_INLINE_VISIBILITY
806    iterator erase(const_iterator __first, const_iterator __last)
807        {return __table_.erase(__first, __last);}
808    _LIBCPP_INLINE_VISIBILITY
809    void clear() _NOEXCEPT {__table_.clear();}
810
811#if _LIBCPP_STD_VER >= 17
812    _LIBCPP_INLINE_VISIBILITY
813    insert_return_type insert(node_type&& __nh)
814    {
815        _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__nh.empty() || __nh.get_allocator() == get_allocator(),
816            "node_type with incompatible allocator passed to unordered_set::insert()");
817        return __table_.template __node_handle_insert_unique<
818            node_type, insert_return_type>(_VSTD::move(__nh));
819    }
820    _LIBCPP_INLINE_VISIBILITY
821    iterator insert(const_iterator __h, node_type&& __nh)
822    {
823        _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__nh.empty() || __nh.get_allocator() == get_allocator(),
824            "node_type with incompatible allocator passed to unordered_set::insert()");
825        return __table_.template __node_handle_insert_unique<node_type>(
826            __h, _VSTD::move(__nh));
827    }
828    _LIBCPP_INLINE_VISIBILITY
829    node_type extract(key_type const& __key)
830    {
831        return __table_.template __node_handle_extract<node_type>(__key);
832    }
833    _LIBCPP_INLINE_VISIBILITY
834    node_type extract(const_iterator __it)
835    {
836        return __table_.template __node_handle_extract<node_type>(__it);
837    }
838
839    template<class _H2, class _P2>
840    _LIBCPP_INLINE_VISIBILITY
841    void merge(unordered_set<key_type, _H2, _P2, allocator_type>& __source)
842    {
843        _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__source.get_allocator() == get_allocator(),
844                                            "merging container with incompatible allocator");
845        __table_.__node_handle_merge_unique(__source.__table_);
846    }
847    template<class _H2, class _P2>
848    _LIBCPP_INLINE_VISIBILITY
849    void merge(unordered_set<key_type, _H2, _P2, allocator_type>&& __source)
850    {
851          _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__source.get_allocator() == get_allocator(),
852                                              "merging container with incompatible allocator");
853        __table_.__node_handle_merge_unique(__source.__table_);
854    }
855    template<class _H2, class _P2>
856    _LIBCPP_INLINE_VISIBILITY
857    void merge(unordered_multiset<key_type, _H2, _P2, allocator_type>& __source)
858    {
859        _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__source.get_allocator() == get_allocator(),
860                                            "merging container with incompatible allocator");
861        __table_.__node_handle_merge_unique(__source.__table_);
862    }
863    template<class _H2, class _P2>
864    _LIBCPP_INLINE_VISIBILITY
865    void merge(unordered_multiset<key_type, _H2, _P2, allocator_type>&& __source)
866    {
867        _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__source.get_allocator() == get_allocator(),
868                                            "merging container with incompatible allocator");
869        __table_.__node_handle_merge_unique(__source.__table_);
870    }
871#endif
872
873    _LIBCPP_INLINE_VISIBILITY
874    void swap(unordered_set& __u)
875        _NOEXCEPT_(__is_nothrow_swappable<__table>::value)
876        {__table_.swap(__u.__table_);}
877
878    _LIBCPP_INLINE_VISIBILITY
879    hasher hash_function() const {return __table_.hash_function();}
880    _LIBCPP_INLINE_VISIBILITY
881    key_equal key_eq() const {return __table_.key_eq();}
882
883    _LIBCPP_INLINE_VISIBILITY
884    iterator       find(const key_type& __k)       {return __table_.find(__k);}
885    _LIBCPP_INLINE_VISIBILITY
886    const_iterator find(const key_type& __k) const {return __table_.find(__k);}
887#if _LIBCPP_STD_VER >= 20
888    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
889    _LIBCPP_INLINE_VISIBILITY
890    iterator       find(const _K2& __k)            {return __table_.find(__k);}
891    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
892    _LIBCPP_INLINE_VISIBILITY
893    const_iterator find(const _K2& __k) const      {return __table_.find(__k);}
894#endif // _LIBCPP_STD_VER >= 20
895
896    _LIBCPP_INLINE_VISIBILITY
897    size_type count(const key_type& __k) const {return __table_.__count_unique(__k);}
898#if _LIBCPP_STD_VER >= 20
899    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
900    _LIBCPP_INLINE_VISIBILITY
901    size_type count(const _K2& __k) const      {return __table_.__count_unique(__k);}
902#endif // _LIBCPP_STD_VER >= 20
903
904#if _LIBCPP_STD_VER >= 20
905    _LIBCPP_INLINE_VISIBILITY
906    bool contains(const key_type& __k) const {return find(__k) != end();}
907
908    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
909    _LIBCPP_INLINE_VISIBILITY
910    bool contains(const _K2& __k) const      {return find(__k) != end();}
911#endif // _LIBCPP_STD_VER >= 20
912
913    _LIBCPP_INLINE_VISIBILITY
914    pair<iterator, iterator>             equal_range(const key_type& __k)
915        {return __table_.__equal_range_unique(__k);}
916    _LIBCPP_INLINE_VISIBILITY
917    pair<const_iterator, const_iterator> equal_range(const key_type& __k) const
918        {return __table_.__equal_range_unique(__k);}
919#if _LIBCPP_STD_VER >= 20
920    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
921    _LIBCPP_INLINE_VISIBILITY
922    pair<iterator, iterator>             equal_range(const _K2& __k)
923        {return __table_.__equal_range_unique(__k);}
924    template <class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
925    _LIBCPP_INLINE_VISIBILITY
926    pair<const_iterator, const_iterator> equal_range(const _K2& __k) const
927        {return __table_.__equal_range_unique(__k);}
928#endif // _LIBCPP_STD_VER >= 20
929
930    _LIBCPP_INLINE_VISIBILITY
931    size_type bucket_count() const _NOEXCEPT {return __table_.bucket_count();}
932    _LIBCPP_INLINE_VISIBILITY
933    size_type max_bucket_count() const _NOEXCEPT {return __table_.max_bucket_count();}
934
935    _LIBCPP_INLINE_VISIBILITY
936    size_type bucket_size(size_type __n) const {return __table_.bucket_size(__n);}
937    _LIBCPP_INLINE_VISIBILITY
938    size_type bucket(const key_type& __k) const {return __table_.bucket(__k);}
939
940    _LIBCPP_INLINE_VISIBILITY
941    local_iterator       begin(size_type __n)        {return __table_.begin(__n);}
942    _LIBCPP_INLINE_VISIBILITY
943    local_iterator       end(size_type __n)          {return __table_.end(__n);}
944    _LIBCPP_INLINE_VISIBILITY
945    const_local_iterator begin(size_type __n) const  {return __table_.cbegin(__n);}
946    _LIBCPP_INLINE_VISIBILITY
947    const_local_iterator end(size_type __n) const    {return __table_.cend(__n);}
948    _LIBCPP_INLINE_VISIBILITY
949    const_local_iterator cbegin(size_type __n) const {return __table_.cbegin(__n);}
950    _LIBCPP_INLINE_VISIBILITY
951    const_local_iterator cend(size_type __n) const   {return __table_.cend(__n);}
952
953    _LIBCPP_INLINE_VISIBILITY
954    float load_factor() const _NOEXCEPT {return __table_.load_factor();}
955    _LIBCPP_INLINE_VISIBILITY
956    float max_load_factor() const _NOEXCEPT {return __table_.max_load_factor();}
957    _LIBCPP_INLINE_VISIBILITY
958    void max_load_factor(float __mlf) {__table_.max_load_factor(__mlf);}
959    _LIBCPP_INLINE_VISIBILITY
960    void rehash(size_type __n) {__table_.__rehash_unique(__n);}
961    _LIBCPP_INLINE_VISIBILITY
962    void reserve(size_type __n) {__table_.__reserve_unique(__n);}
963};
964
965#if _LIBCPP_STD_VER >= 17
966template<class _InputIterator,
967         class _Hash = hash<__iter_value_type<_InputIterator>>,
968         class _Pred = equal_to<__iter_value_type<_InputIterator>>,
969         class _Allocator = allocator<__iter_value_type<_InputIterator>>,
970         class = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
971         class = enable_if_t<!__is_allocator<_Hash>::value>,
972         class = enable_if_t<!is_integral<_Hash>::value>,
973         class = enable_if_t<!__is_allocator<_Pred>::value>,
974         class = enable_if_t<__is_allocator<_Allocator>::value>>
975unordered_set(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type = 0,
976              _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
977  -> unordered_set<__iter_value_type<_InputIterator>, _Hash, _Pred, _Allocator>;
978
979#if _LIBCPP_STD_VER >= 23
980template <ranges::input_range _Range,
981          class _Hash = hash<ranges::range_value_t<_Range>>,
982          class _Pred = equal_to<ranges::range_value_t<_Range>>,
983          class _Allocator = allocator<ranges::range_value_t<_Range>>,
984          class = enable_if_t<!__is_allocator<_Hash>::value>,
985          class = enable_if_t<!is_integral<_Hash>::value>,
986          class = enable_if_t<!__is_allocator<_Pred>::value>,
987          class = enable_if_t<__is_allocator<_Allocator>::value>>
988unordered_set(from_range_t, _Range&&, typename allocator_traits<_Allocator>::size_type = 0,
989              _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
990  -> unordered_set<ranges::range_value_t<_Range>, _Hash, _Pred, _Allocator>; // C++23
991#endif
992
993template<class _Tp, class _Hash = hash<_Tp>,
994         class _Pred = equal_to<_Tp>,
995         class _Allocator = allocator<_Tp>,
996         class = enable_if_t<!__is_allocator<_Hash>::value>,
997         class = enable_if_t<!is_integral<_Hash>::value>,
998         class = enable_if_t<!__is_allocator<_Pred>::value>,
999         class = enable_if_t<__is_allocator<_Allocator>::value>>
1000unordered_set(initializer_list<_Tp>, typename allocator_traits<_Allocator>::size_type = 0,
1001              _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
1002  -> unordered_set<_Tp, _Hash, _Pred, _Allocator>;
1003
1004template<class _InputIterator, class _Allocator,
1005         class = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
1006         class = enable_if_t<__is_allocator<_Allocator>::value>>
1007unordered_set(_InputIterator, _InputIterator,
1008              typename allocator_traits<_Allocator>::size_type, _Allocator)
1009  -> unordered_set<__iter_value_type<_InputIterator>,
1010                   hash<__iter_value_type<_InputIterator>>,
1011                   equal_to<__iter_value_type<_InputIterator>>,
1012                   _Allocator>;
1013
1014template<class _InputIterator, class _Hash, class _Allocator,
1015         class = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
1016         class = enable_if_t<!__is_allocator<_Hash>::value>,
1017         class = enable_if_t<!is_integral<_Hash>::value>,
1018         class = enable_if_t<__is_allocator<_Allocator>::value>>
1019unordered_set(_InputIterator, _InputIterator,
1020              typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
1021  -> unordered_set<__iter_value_type<_InputIterator>, _Hash,
1022                   equal_to<__iter_value_type<_InputIterator>>,
1023                   _Allocator>;
1024
1025#if _LIBCPP_STD_VER >= 23
1026
1027template <ranges::input_range _Range, class _Allocator,
1028          class = enable_if_t<__is_allocator<_Allocator>::value>>
1029unordered_set(from_range_t, _Range&&, typename allocator_traits<_Allocator>::size_type, _Allocator)
1030  -> unordered_set<ranges::range_value_t<_Range>, hash<ranges::range_value_t<_Range>>,
1031                   equal_to<ranges::range_value_t<_Range>>, _Allocator>;
1032
1033template <ranges::input_range _Range, class _Allocator,
1034          class = enable_if_t<__is_allocator<_Allocator>::value>>
1035unordered_set(from_range_t, _Range&&, _Allocator)
1036  -> unordered_set<ranges::range_value_t<_Range>, hash<ranges::range_value_t<_Range>>,
1037                   equal_to<ranges::range_value_t<_Range>>, _Allocator>;
1038
1039template <ranges::input_range _Range, class _Hash, class _Allocator,
1040          class = enable_if_t<!__is_allocator<_Hash>::value>,
1041          class = enable_if_t<!is_integral<_Hash>::value>,
1042          class = enable_if_t<__is_allocator<_Allocator>::value>>
1043unordered_set(from_range_t, _Range&&, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
1044  -> unordered_set<ranges::range_value_t<_Range>, _Hash, equal_to<ranges::range_value_t<_Range>>, _Allocator>;
1045
1046#endif
1047
1048template<class _Tp, class _Allocator,
1049         class = enable_if_t<__is_allocator<_Allocator>::value>>
1050unordered_set(initializer_list<_Tp>, typename allocator_traits<_Allocator>::size_type, _Allocator)
1051  -> unordered_set<_Tp, hash<_Tp>, equal_to<_Tp>, _Allocator>;
1052
1053template<class _Tp, class _Hash, class _Allocator,
1054         class = enable_if_t<!__is_allocator<_Hash>::value>,
1055         class = enable_if_t<!is_integral<_Hash>::value>,
1056         class = enable_if_t<__is_allocator<_Allocator>::value>>
1057unordered_set(initializer_list<_Tp>, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
1058  -> unordered_set<_Tp, _Hash, equal_to<_Tp>, _Allocator>;
1059#endif
1060
1061template <class _Value, class _Hash, class _Pred, class _Alloc>
1062unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(size_type __n,
1063        const hasher& __hf, const key_equal& __eql)
1064    : __table_(__hf, __eql)
1065{
1066    __table_.__rehash_unique(__n);
1067}
1068
1069template <class _Value, class _Hash, class _Pred, class _Alloc>
1070unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(size_type __n,
1071        const hasher& __hf, const key_equal& __eql, const allocator_type& __a)
1072    : __table_(__hf, __eql, __a)
1073{
1074    __table_.__rehash_unique(__n);
1075}
1076
1077template <class _Value, class _Hash, class _Pred, class _Alloc>
1078template <class _InputIterator>
1079unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1080        _InputIterator __first, _InputIterator __last)
1081{
1082    insert(__first, __last);
1083}
1084
1085template <class _Value, class _Hash, class _Pred, class _Alloc>
1086template <class _InputIterator>
1087unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1088        _InputIterator __first, _InputIterator __last, size_type __n,
1089        const hasher& __hf, const key_equal& __eql)
1090    : __table_(__hf, __eql)
1091{
1092    __table_.__rehash_unique(__n);
1093    insert(__first, __last);
1094}
1095
1096template <class _Value, class _Hash, class _Pred, class _Alloc>
1097template <class _InputIterator>
1098unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1099        _InputIterator __first, _InputIterator __last, size_type __n,
1100        const hasher& __hf, const key_equal& __eql, const allocator_type& __a)
1101    : __table_(__hf, __eql, __a)
1102{
1103    __table_.__rehash_unique(__n);
1104    insert(__first, __last);
1105}
1106
1107template <class _Value, class _Hash, class _Pred, class _Alloc>
1108inline
1109unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1110        const allocator_type& __a)
1111    : __table_(__a)
1112{
1113}
1114
1115template <class _Value, class _Hash, class _Pred, class _Alloc>
1116unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1117        const unordered_set& __u)
1118    : __table_(__u.__table_)
1119{
1120    __table_.__rehash_unique(__u.bucket_count());
1121    insert(__u.begin(), __u.end());
1122}
1123
1124template <class _Value, class _Hash, class _Pred, class _Alloc>
1125unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1126        const unordered_set& __u, const allocator_type& __a)
1127    : __table_(__u.__table_, __a)
1128{
1129    __table_.__rehash_unique(__u.bucket_count());
1130    insert(__u.begin(), __u.end());
1131}
1132
1133#ifndef _LIBCPP_CXX03_LANG
1134
1135template <class _Value, class _Hash, class _Pred, class _Alloc>
1136inline
1137unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1138        unordered_set&& __u)
1139    _NOEXCEPT_(is_nothrow_move_constructible<__table>::value)
1140    : __table_(_VSTD::move(__u.__table_))
1141{
1142}
1143
1144template <class _Value, class _Hash, class _Pred, class _Alloc>
1145unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1146        unordered_set&& __u, const allocator_type& __a)
1147    : __table_(_VSTD::move(__u.__table_), __a)
1148{
1149    if (__a != __u.get_allocator())
1150    {
1151        iterator __i = __u.begin();
1152        while (__u.size() != 0)
1153            __table_.__insert_unique(_VSTD::move(__u.__table_.remove(__i++)->__value_));
1154    }
1155}
1156
1157template <class _Value, class _Hash, class _Pred, class _Alloc>
1158unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1159        initializer_list<value_type> __il)
1160{
1161    insert(__il.begin(), __il.end());
1162}
1163
1164template <class _Value, class _Hash, class _Pred, class _Alloc>
1165unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1166        initializer_list<value_type> __il, size_type __n, const hasher& __hf,
1167        const key_equal& __eql)
1168    : __table_(__hf, __eql)
1169{
1170    __table_.__rehash_unique(__n);
1171    insert(__il.begin(), __il.end());
1172}
1173
1174template <class _Value, class _Hash, class _Pred, class _Alloc>
1175unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1176        initializer_list<value_type> __il, size_type __n, const hasher& __hf,
1177        const key_equal& __eql, const allocator_type& __a)
1178    : __table_(__hf, __eql, __a)
1179{
1180    __table_.__rehash_unique(__n);
1181    insert(__il.begin(), __il.end());
1182}
1183
1184template <class _Value, class _Hash, class _Pred, class _Alloc>
1185inline
1186unordered_set<_Value, _Hash, _Pred, _Alloc>&
1187unordered_set<_Value, _Hash, _Pred, _Alloc>::operator=(unordered_set&& __u)
1188    _NOEXCEPT_(is_nothrow_move_assignable<__table>::value)
1189{
1190    __table_ = _VSTD::move(__u.__table_);
1191    return *this;
1192}
1193
1194template <class _Value, class _Hash, class _Pred, class _Alloc>
1195inline
1196unordered_set<_Value, _Hash, _Pred, _Alloc>&
1197unordered_set<_Value, _Hash, _Pred, _Alloc>::operator=(
1198        initializer_list<value_type> __il)
1199{
1200    __table_.__assign_unique(__il.begin(), __il.end());
1201    return *this;
1202}
1203
1204#endif // _LIBCPP_CXX03_LANG
1205
1206template <class _Value, class _Hash, class _Pred, class _Alloc>
1207template <class _InputIterator>
1208inline
1209void
1210unordered_set<_Value, _Hash, _Pred, _Alloc>::insert(_InputIterator __first,
1211                                                    _InputIterator __last)
1212{
1213    for (; __first != __last; ++__first)
1214        __table_.__insert_unique(*__first);
1215}
1216
1217template <class _Value, class _Hash, class _Pred, class _Alloc>
1218inline _LIBCPP_INLINE_VISIBILITY
1219void
1220swap(unordered_set<_Value, _Hash, _Pred, _Alloc>& __x,
1221     unordered_set<_Value, _Hash, _Pred, _Alloc>& __y)
1222    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
1223{
1224    __x.swap(__y);
1225}
1226
1227#if _LIBCPP_STD_VER >= 20
1228template <class _Value, class _Hash, class _Pred, class _Alloc,
1229          class _Predicate>
1230inline _LIBCPP_INLINE_VISIBILITY
1231    typename unordered_set<_Value, _Hash, _Pred, _Alloc>::size_type
1232    erase_if(unordered_set<_Value, _Hash, _Pred, _Alloc>& __c,
1233             _Predicate __pred) {
1234  return _VSTD::__libcpp_erase_if_container(__c, __pred);
1235}
1236#endif
1237
1238template <class _Value, class _Hash, class _Pred, class _Alloc>
1239_LIBCPP_HIDE_FROM_ABI bool
1240operator==(const unordered_set<_Value, _Hash, _Pred, _Alloc>& __x,
1241           const unordered_set<_Value, _Hash, _Pred, _Alloc>& __y)
1242{
1243    if (__x.size() != __y.size())
1244        return false;
1245    typedef typename unordered_set<_Value, _Hash, _Pred, _Alloc>::const_iterator
1246                                                                 const_iterator;
1247    for (const_iterator __i = __x.begin(), __ex = __x.end(), __ey = __y.end();
1248            __i != __ex; ++__i)
1249    {
1250        const_iterator __j = __y.find(*__i);
1251        if (__j == __ey || !(*__i == *__j))
1252            return false;
1253    }
1254    return true;
1255}
1256
1257#if _LIBCPP_STD_VER <= 17
1258
1259template <class _Value, class _Hash, class _Pred, class _Alloc>
1260inline _LIBCPP_INLINE_VISIBILITY
1261bool
1262operator!=(const unordered_set<_Value, _Hash, _Pred, _Alloc>& __x,
1263           const unordered_set<_Value, _Hash, _Pred, _Alloc>& __y)
1264{
1265    return !(__x == __y);
1266}
1267
1268#endif
1269
1270template <class _Value, class _Hash = hash<_Value>, class _Pred = equal_to<_Value>,
1271          class _Alloc = allocator<_Value> >
1272class _LIBCPP_TEMPLATE_VIS unordered_multiset
1273{
1274public:
1275    // types
1276    typedef _Value                                                     key_type;
1277    typedef key_type                                                   value_type;
1278    typedef __type_identity_t<_Hash>                                   hasher;
1279    typedef __type_identity_t<_Pred>                                   key_equal;
1280    typedef __type_identity_t<_Alloc>                                  allocator_type;
1281    typedef value_type&                                                reference;
1282    typedef const value_type&                                          const_reference;
1283    static_assert((is_same<value_type, typename allocator_type::value_type>::value),
1284                  "Allocator::value_type must be same type as value_type");
1285
1286private:
1287    typedef __hash_table<value_type, hasher, key_equal, allocator_type> __table;
1288
1289    __table __table_;
1290
1291public:
1292    typedef typename __table::pointer         pointer;
1293    typedef typename __table::const_pointer   const_pointer;
1294    typedef typename __table::size_type       size_type;
1295    typedef typename __table::difference_type difference_type;
1296
1297    typedef typename __table::const_iterator       iterator;
1298    typedef typename __table::const_iterator       const_iterator;
1299    typedef typename __table::const_local_iterator local_iterator;
1300    typedef typename __table::const_local_iterator const_local_iterator;
1301
1302#if _LIBCPP_STD_VER >= 17
1303    typedef __set_node_handle<typename __table::__node, allocator_type> node_type;
1304#endif
1305
1306    template <class _Value2, class _Hash2, class _Pred2, class _Alloc2>
1307        friend class _LIBCPP_TEMPLATE_VIS unordered_set;
1308    template <class _Value2, class _Hash2, class _Pred2, class _Alloc2>
1309        friend class _LIBCPP_TEMPLATE_VIS unordered_multiset;
1310
1311    _LIBCPP_INLINE_VISIBILITY
1312    unordered_multiset()
1313        _NOEXCEPT_(is_nothrow_default_constructible<__table>::value)
1314    {
1315    }
1316    explicit _LIBCPP_HIDE_FROM_ABI unordered_multiset(size_type __n, const hasher& __hf = hasher(),
1317                                const key_equal& __eql = key_equal());
1318    _LIBCPP_HIDE_FROM_ABI unordered_multiset(size_type __n, const hasher& __hf,
1319                       const key_equal& __eql, const allocator_type& __a);
1320#if _LIBCPP_STD_VER >= 14
1321    inline _LIBCPP_INLINE_VISIBILITY
1322    unordered_multiset(size_type __n, const allocator_type& __a)
1323        : unordered_multiset(__n, hasher(), key_equal(), __a) {}
1324    inline _LIBCPP_INLINE_VISIBILITY
1325    unordered_multiset(size_type __n, const hasher& __hf, const allocator_type& __a)
1326        : unordered_multiset(__n, __hf, key_equal(), __a) {}
1327#endif
1328    template <class _InputIterator>
1329    _LIBCPP_HIDE_FROM_ABI unordered_multiset(_InputIterator __first, _InputIterator __last);
1330    template <class _InputIterator>
1331    _LIBCPP_HIDE_FROM_ABI unordered_multiset(_InputIterator __first, _InputIterator __last,
1332                      size_type __n, const hasher& __hf = hasher(),
1333                      const key_equal& __eql = key_equal());
1334    template <class _InputIterator>
1335    _LIBCPP_HIDE_FROM_ABI unordered_multiset(_InputIterator __first, _InputIterator __last,
1336                      size_type __n , const hasher& __hf,
1337                      const key_equal& __eql, const allocator_type& __a);
1338
1339#if _LIBCPP_STD_VER >= 23
1340    template <_ContainerCompatibleRange<value_type> _Range>
1341    _LIBCPP_HIDE_FROM_ABI
1342    unordered_multiset(from_range_t, _Range&& __range, size_type __n = /*implementation-defined*/0,
1343                  const hasher& __hf = hasher(), const key_equal& __eql = key_equal(),
1344                  const allocator_type& __a = allocator_type())
1345    : __table_(__hf, __eql, __a) {
1346      if (__n > 0) {
1347        __table_.__rehash_multi(__n);
1348      }
1349      insert_range(std::forward<_Range>(__range));
1350    }
1351#endif
1352
1353#if _LIBCPP_STD_VER >= 14
1354    template <class _InputIterator>
1355    inline _LIBCPP_INLINE_VISIBILITY
1356    unordered_multiset(_InputIterator __first, _InputIterator __last,
1357                       size_type __n, const allocator_type& __a)
1358        : unordered_multiset(__first, __last, __n, hasher(), key_equal(), __a) {}
1359    template <class _InputIterator>
1360    inline _LIBCPP_INLINE_VISIBILITY
1361    unordered_multiset(_InputIterator __first, _InputIterator __last,
1362                       size_type __n, const hasher& __hf, const allocator_type& __a)
1363        : unordered_multiset(__first, __last, __n, __hf, key_equal(), __a) {}
1364#endif
1365
1366#if _LIBCPP_STD_VER >= 23
1367    template <_ContainerCompatibleRange<value_type> _Range>
1368    _LIBCPP_HIDE_FROM_ABI
1369    unordered_multiset(from_range_t, _Range&& __range, size_type __n, const allocator_type& __a)
1370        : unordered_multiset(from_range, std::forward<_Range>(__range), __n, hasher(), key_equal(), __a) {}
1371
1372    template <_ContainerCompatibleRange<value_type> _Range>
1373    _LIBCPP_HIDE_FROM_ABI
1374    unordered_multiset(from_range_t, _Range&& __range, size_type __n, const hasher& __hf, const allocator_type& __a)
1375        : unordered_multiset(from_range, std::forward<_Range>(__range), __n, __hf, key_equal(), __a) {}
1376#endif
1377
1378    _LIBCPP_INLINE_VISIBILITY
1379    explicit unordered_multiset(const allocator_type& __a);
1380    _LIBCPP_HIDE_FROM_ABI unordered_multiset(const unordered_multiset& __u);
1381    _LIBCPP_HIDE_FROM_ABI unordered_multiset(const unordered_multiset& __u, const allocator_type& __a);
1382#ifndef _LIBCPP_CXX03_LANG
1383    _LIBCPP_INLINE_VISIBILITY
1384    unordered_multiset(unordered_multiset&& __u)
1385        _NOEXCEPT_(is_nothrow_move_constructible<__table>::value);
1386    _LIBCPP_HIDE_FROM_ABI unordered_multiset(unordered_multiset&& __u, const allocator_type& __a);
1387    _LIBCPP_HIDE_FROM_ABI unordered_multiset(initializer_list<value_type> __il);
1388    _LIBCPP_HIDE_FROM_ABI unordered_multiset(initializer_list<value_type> __il, size_type __n,
1389                       const hasher& __hf = hasher(),
1390                       const key_equal& __eql = key_equal());
1391    _LIBCPP_HIDE_FROM_ABI unordered_multiset(initializer_list<value_type> __il, size_type __n,
1392                       const hasher& __hf, const key_equal& __eql,
1393                       const allocator_type& __a);
1394#if _LIBCPP_STD_VER >= 14
1395    inline _LIBCPP_INLINE_VISIBILITY
1396    unordered_multiset(initializer_list<value_type> __il, size_type __n, const allocator_type& __a)
1397      : unordered_multiset(__il, __n, hasher(), key_equal(), __a) {}
1398    inline _LIBCPP_INLINE_VISIBILITY
1399    unordered_multiset(initializer_list<value_type> __il, size_type __n, const hasher& __hf, const allocator_type& __a)
1400      : unordered_multiset(__il, __n, __hf, key_equal(), __a) {}
1401#endif
1402#endif // _LIBCPP_CXX03_LANG
1403    _LIBCPP_INLINE_VISIBILITY
1404    ~unordered_multiset() {
1405        static_assert(sizeof(std::__diagnose_unordered_container_requirements<_Value, _Hash, _Pred>(0)), "");
1406    }
1407
1408    _LIBCPP_INLINE_VISIBILITY
1409    unordered_multiset& operator=(const unordered_multiset& __u)
1410    {
1411        __table_ = __u.__table_;
1412        return *this;
1413    }
1414#ifndef _LIBCPP_CXX03_LANG
1415    _LIBCPP_INLINE_VISIBILITY
1416    unordered_multiset& operator=(unordered_multiset&& __u)
1417        _NOEXCEPT_(is_nothrow_move_assignable<__table>::value);
1418    _LIBCPP_HIDE_FROM_ABI unordered_multiset& operator=(initializer_list<value_type> __il);
1419#endif // _LIBCPP_CXX03_LANG
1420
1421    _LIBCPP_INLINE_VISIBILITY
1422    allocator_type get_allocator() const _NOEXCEPT
1423        {return allocator_type(__table_.__node_alloc());}
1424
1425    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
1426    bool      empty() const _NOEXCEPT {return __table_.size() == 0;}
1427    _LIBCPP_INLINE_VISIBILITY
1428    size_type size() const _NOEXCEPT  {return __table_.size();}
1429    _LIBCPP_INLINE_VISIBILITY
1430    size_type max_size() const _NOEXCEPT {return __table_.max_size();}
1431
1432    _LIBCPP_INLINE_VISIBILITY
1433    iterator       begin() _NOEXCEPT        {return __table_.begin();}
1434    _LIBCPP_INLINE_VISIBILITY
1435    iterator       end() _NOEXCEPT          {return __table_.end();}
1436    _LIBCPP_INLINE_VISIBILITY
1437    const_iterator begin()  const _NOEXCEPT {return __table_.begin();}
1438    _LIBCPP_INLINE_VISIBILITY
1439    const_iterator end()    const _NOEXCEPT {return __table_.end();}
1440    _LIBCPP_INLINE_VISIBILITY
1441    const_iterator cbegin() const _NOEXCEPT {return __table_.begin();}
1442    _LIBCPP_INLINE_VISIBILITY
1443    const_iterator cend()   const _NOEXCEPT {return __table_.end();}
1444
1445#ifndef _LIBCPP_CXX03_LANG
1446    template <class... _Args>
1447        _LIBCPP_INLINE_VISIBILITY
1448        iterator emplace(_Args&&... __args)
1449            {return __table_.__emplace_multi(_VSTD::forward<_Args>(__args)...);}
1450    template <class... _Args>
1451        _LIBCPP_INLINE_VISIBILITY
1452        iterator emplace_hint(const_iterator __p, _Args&&... __args)
1453            {return __table_.__emplace_hint_multi(__p, _VSTD::forward<_Args>(__args)...);}
1454
1455    _LIBCPP_INLINE_VISIBILITY
1456    iterator insert(value_type&& __x) {return __table_.__insert_multi(_VSTD::move(__x));}
1457    _LIBCPP_INLINE_VISIBILITY
1458    iterator insert(const_iterator __p, value_type&& __x)
1459        {return __table_.__insert_multi(__p, _VSTD::move(__x));}
1460    _LIBCPP_INLINE_VISIBILITY
1461    void insert(initializer_list<value_type> __il)
1462        {insert(__il.begin(), __il.end());}
1463#endif // _LIBCPP_CXX03_LANG
1464
1465    _LIBCPP_INLINE_VISIBILITY
1466    iterator insert(const value_type& __x) {return __table_.__insert_multi(__x);}
1467
1468    _LIBCPP_INLINE_VISIBILITY
1469    iterator insert(const_iterator __p, const value_type& __x)
1470        {return __table_.__insert_multi(__p, __x);}
1471
1472    template <class _InputIterator>
1473        _LIBCPP_INLINE_VISIBILITY
1474        void insert(_InputIterator __first, _InputIterator __last);
1475
1476#if _LIBCPP_STD_VER >= 23
1477    template <_ContainerCompatibleRange<value_type> _Range>
1478    _LIBCPP_HIDE_FROM_ABI
1479    void insert_range(_Range&& __range) {
1480      for (auto&& __element : __range) {
1481        __table_.__insert_multi(std::forward<decltype(__element)>(__element));
1482      }
1483    }
1484#endif
1485
1486#if _LIBCPP_STD_VER >= 17
1487    _LIBCPP_INLINE_VISIBILITY
1488    iterator insert(node_type&& __nh)
1489    {
1490        _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__nh.empty() || __nh.get_allocator() == get_allocator(),
1491            "node_type with incompatible allocator passed to unordered_multiset::insert()");
1492        return __table_.template __node_handle_insert_multi<node_type>(
1493            _VSTD::move(__nh));
1494    }
1495    _LIBCPP_INLINE_VISIBILITY
1496    iterator insert(const_iterator __hint, node_type&& __nh)
1497    {
1498        _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__nh.empty() || __nh.get_allocator() == get_allocator(),
1499            "node_type with incompatible allocator passed to unordered_multiset::insert()");
1500        return __table_.template __node_handle_insert_multi<node_type>(
1501            __hint, _VSTD::move(__nh));
1502    }
1503    _LIBCPP_INLINE_VISIBILITY
1504    node_type extract(const_iterator __position)
1505    {
1506        return __table_.template __node_handle_extract<node_type>(
1507            __position);
1508    }
1509    _LIBCPP_INLINE_VISIBILITY
1510    node_type extract(key_type const& __key)
1511    {
1512        return __table_.template __node_handle_extract<node_type>(__key);
1513    }
1514
1515    template <class _H2, class _P2>
1516    _LIBCPP_INLINE_VISIBILITY
1517    void merge(unordered_multiset<key_type, _H2, _P2, allocator_type>& __source)
1518    {
1519        _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__source.get_allocator() == get_allocator(),
1520                                            "merging container with incompatible allocator");
1521        return __table_.__node_handle_merge_multi(__source.__table_);
1522    }
1523    template <class _H2, class _P2>
1524    _LIBCPP_INLINE_VISIBILITY
1525    void merge(unordered_multiset<key_type, _H2, _P2, allocator_type>&& __source)
1526    {
1527        _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__source.get_allocator() == get_allocator(),
1528                                            "merging container with incompatible allocator");
1529        return __table_.__node_handle_merge_multi(__source.__table_);
1530    }
1531    template <class _H2, class _P2>
1532    _LIBCPP_INLINE_VISIBILITY
1533    void merge(unordered_set<key_type, _H2, _P2, allocator_type>& __source)
1534    {
1535        _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__source.get_allocator() == get_allocator(),
1536                                            "merging container with incompatible allocator");
1537        return __table_.__node_handle_merge_multi(__source.__table_);
1538    }
1539    template <class _H2, class _P2>
1540    _LIBCPP_INLINE_VISIBILITY
1541    void merge(unordered_set<key_type, _H2, _P2, allocator_type>&& __source)
1542    {
1543        _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__source.get_allocator() == get_allocator(),
1544                                            "merging container with incompatible allocator");
1545        return __table_.__node_handle_merge_multi(__source.__table_);
1546    }
1547#endif
1548
1549    _LIBCPP_INLINE_VISIBILITY
1550    iterator erase(const_iterator __p) {return __table_.erase(__p);}
1551    _LIBCPP_INLINE_VISIBILITY
1552    size_type erase(const key_type& __k) {return __table_.__erase_multi(__k);}
1553    _LIBCPP_INLINE_VISIBILITY
1554    iterator erase(const_iterator __first, const_iterator __last)
1555        {return __table_.erase(__first, __last);}
1556    _LIBCPP_INLINE_VISIBILITY
1557    void clear() _NOEXCEPT {__table_.clear();}
1558
1559    _LIBCPP_INLINE_VISIBILITY
1560    void swap(unordered_multiset& __u)
1561        _NOEXCEPT_(__is_nothrow_swappable<__table>::value)
1562        {__table_.swap(__u.__table_);}
1563
1564    _LIBCPP_INLINE_VISIBILITY
1565    hasher hash_function() const {return __table_.hash_function();}
1566    _LIBCPP_INLINE_VISIBILITY
1567    key_equal key_eq() const {return __table_.key_eq();}
1568
1569    _LIBCPP_INLINE_VISIBILITY
1570    iterator       find(const key_type& __k)       {return __table_.find(__k);}
1571    _LIBCPP_INLINE_VISIBILITY
1572    const_iterator find(const key_type& __k) const {return __table_.find(__k);}
1573#if _LIBCPP_STD_VER >= 20
1574    template<class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
1575    _LIBCPP_INLINE_VISIBILITY
1576    iterator       find(const _K2& __k)            {return __table_.find(__k);}
1577    template<class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
1578    _LIBCPP_INLINE_VISIBILITY
1579    const_iterator find(const _K2& __k) const      {return __table_.find(__k);}
1580#endif // _LIBCPP_STD_VER >= 20
1581
1582    _LIBCPP_INLINE_VISIBILITY
1583    size_type count(const key_type& __k) const {return __table_.__count_multi(__k);}
1584#if _LIBCPP_STD_VER >= 20
1585    template<class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
1586    _LIBCPP_INLINE_VISIBILITY
1587    size_type count(const _K2& __k) const      {return __table_.__count_multi(__k);}
1588#endif // _LIBCPP_STD_VER >= 20
1589
1590#if _LIBCPP_STD_VER >= 20
1591    _LIBCPP_INLINE_VISIBILITY
1592    bool contains(const key_type& __k) const {return find(__k) != end();}
1593
1594    template<class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
1595    _LIBCPP_INLINE_VISIBILITY
1596    bool contains(const _K2& __k) const      {return find(__k) != end();}
1597#endif // _LIBCPP_STD_VER >= 20
1598
1599    _LIBCPP_INLINE_VISIBILITY
1600    pair<iterator, iterator>             equal_range(const key_type& __k)
1601        {return __table_.__equal_range_multi(__k);}
1602    _LIBCPP_INLINE_VISIBILITY
1603    pair<const_iterator, const_iterator> equal_range(const key_type& __k) const
1604        {return __table_.__equal_range_multi(__k);}
1605#if _LIBCPP_STD_VER >= 20
1606    template<class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
1607    _LIBCPP_INLINE_VISIBILITY
1608    pair<iterator, iterator>             equal_range(const _K2& __k)
1609        {return __table_.__equal_range_multi(__k);}
1610    template<class _K2, enable_if_t<__is_transparent<hasher, _K2>::value && __is_transparent<key_equal, _K2>::value>* = nullptr>
1611    _LIBCPP_INLINE_VISIBILITY
1612    pair<const_iterator, const_iterator> equal_range(const _K2& __k) const
1613        {return __table_.__equal_range_multi(__k);}
1614#endif // _LIBCPP_STD_VER >= 20
1615
1616    _LIBCPP_INLINE_VISIBILITY
1617    size_type bucket_count() const _NOEXCEPT {return __table_.bucket_count();}
1618    _LIBCPP_INLINE_VISIBILITY
1619    size_type max_bucket_count() const _NOEXCEPT {return __table_.max_bucket_count();}
1620
1621    _LIBCPP_INLINE_VISIBILITY
1622    size_type bucket_size(size_type __n) const {return __table_.bucket_size(__n);}
1623    _LIBCPP_INLINE_VISIBILITY
1624    size_type bucket(const key_type& __k) const {return __table_.bucket(__k);}
1625
1626    _LIBCPP_INLINE_VISIBILITY
1627    local_iterator       begin(size_type __n)        {return __table_.begin(__n);}
1628    _LIBCPP_INLINE_VISIBILITY
1629    local_iterator       end(size_type __n)          {return __table_.end(__n);}
1630    _LIBCPP_INLINE_VISIBILITY
1631    const_local_iterator begin(size_type __n) const  {return __table_.cbegin(__n);}
1632    _LIBCPP_INLINE_VISIBILITY
1633    const_local_iterator end(size_type __n) const    {return __table_.cend(__n);}
1634    _LIBCPP_INLINE_VISIBILITY
1635    const_local_iterator cbegin(size_type __n) const {return __table_.cbegin(__n);}
1636    _LIBCPP_INLINE_VISIBILITY
1637    const_local_iterator cend(size_type __n) const   {return __table_.cend(__n);}
1638
1639    _LIBCPP_INLINE_VISIBILITY
1640    float load_factor() const _NOEXCEPT {return __table_.load_factor();}
1641    _LIBCPP_INLINE_VISIBILITY
1642    float max_load_factor() const _NOEXCEPT {return __table_.max_load_factor();}
1643    _LIBCPP_INLINE_VISIBILITY
1644    void max_load_factor(float __mlf) {__table_.max_load_factor(__mlf);}
1645    _LIBCPP_INLINE_VISIBILITY
1646    void rehash(size_type __n) {__table_.__rehash_multi(__n);}
1647    _LIBCPP_INLINE_VISIBILITY
1648    void reserve(size_type __n) {__table_.__reserve_multi(__n);}
1649};
1650
1651#if _LIBCPP_STD_VER >= 17
1652template<class _InputIterator,
1653         class _Hash = hash<__iter_value_type<_InputIterator>>,
1654         class _Pred = equal_to<__iter_value_type<_InputIterator>>,
1655         class _Allocator = allocator<__iter_value_type<_InputIterator>>,
1656         class = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
1657         class = enable_if_t<!__is_allocator<_Hash>::value>,
1658         class = enable_if_t<!is_integral<_Hash>::value>,
1659         class = enable_if_t<!__is_allocator<_Pred>::value>,
1660         class = enable_if_t<__is_allocator<_Allocator>::value>>
1661unordered_multiset(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type = 0,
1662              _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
1663  -> unordered_multiset<__iter_value_type<_InputIterator>, _Hash, _Pred, _Allocator>;
1664
1665#if _LIBCPP_STD_VER >= 23
1666template <ranges::input_range _Range,
1667          class _Hash = hash<ranges::range_value_t<_Range>>,
1668          class _Pred = equal_to<ranges::range_value_t<_Range>>,
1669          class _Allocator = allocator<ranges::range_value_t<_Range>>,
1670          class = enable_if_t<!__is_allocator<_Hash>::value>,
1671          class = enable_if_t<!is_integral<_Hash>::value>,
1672          class = enable_if_t<!__is_allocator<_Pred>::value>,
1673          class = enable_if_t<__is_allocator<_Allocator>::value>>
1674unordered_multiset(from_range_t, _Range&&, typename allocator_traits<_Allocator>::size_type = 0,
1675              _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
1676  -> unordered_multiset<ranges::range_value_t<_Range>, _Hash, _Pred, _Allocator>; // C++23
1677#endif
1678
1679template<class _Tp, class _Hash = hash<_Tp>,
1680         class _Pred = equal_to<_Tp>, class _Allocator = allocator<_Tp>,
1681         class = enable_if_t<!__is_allocator<_Hash>::value>,
1682         class = enable_if_t<!is_integral<_Hash>::value>,
1683         class = enable_if_t<!__is_allocator<_Pred>::value>,
1684         class = enable_if_t<__is_allocator<_Allocator>::value>>
1685unordered_multiset(initializer_list<_Tp>, typename allocator_traits<_Allocator>::size_type = 0,
1686              _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
1687  -> unordered_multiset<_Tp, _Hash, _Pred, _Allocator>;
1688
1689template<class _InputIterator, class _Allocator,
1690         class = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
1691         class = enable_if_t<__is_allocator<_Allocator>::value>>
1692unordered_multiset(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type, _Allocator)
1693  -> unordered_multiset<__iter_value_type<_InputIterator>,
1694                   hash<__iter_value_type<_InputIterator>>,
1695                   equal_to<__iter_value_type<_InputIterator>>,
1696                   _Allocator>;
1697
1698template<class _InputIterator, class _Hash, class _Allocator,
1699         class = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
1700         class = enable_if_t<!__is_allocator<_Hash>::value>,
1701         class = enable_if_t<!is_integral<_Hash>::value>,
1702         class = enable_if_t<__is_allocator<_Allocator>::value>>
1703unordered_multiset(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type,
1704              _Hash, _Allocator)
1705  -> unordered_multiset<__iter_value_type<_InputIterator>, _Hash,
1706                   equal_to<__iter_value_type<_InputIterator>>,
1707                   _Allocator>;
1708
1709#if _LIBCPP_STD_VER >= 23
1710
1711template <ranges::input_range _Range, class _Allocator,
1712          class = enable_if_t<__is_allocator<_Allocator>::value>>
1713unordered_multiset(from_range_t, _Range&&, typename allocator_traits<_Allocator>::size_type, _Allocator)
1714  -> unordered_multiset<ranges::range_value_t<_Range>, hash<ranges::range_value_t<_Range>>,
1715                   equal_to<ranges::range_value_t<_Range>>, _Allocator>;
1716
1717template <ranges::input_range _Range, class _Allocator,
1718          class = enable_if_t<__is_allocator<_Allocator>::value>>
1719unordered_multiset(from_range_t, _Range&&, _Allocator)
1720  -> unordered_multiset<ranges::range_value_t<_Range>, hash<ranges::range_value_t<_Range>>,
1721                   equal_to<ranges::range_value_t<_Range>>, _Allocator>;
1722
1723template <ranges::input_range _Range, class _Hash, class _Allocator,
1724          class = enable_if_t<!__is_allocator<_Hash>::value>,
1725          class = enable_if_t<!is_integral<_Hash>::value>,
1726          class = enable_if_t<__is_allocator<_Allocator>::value>>
1727unordered_multiset(from_range_t, _Range&&, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
1728  -> unordered_multiset<ranges::range_value_t<_Range>, _Hash, equal_to<ranges::range_value_t<_Range>>, _Allocator>;
1729
1730#endif
1731
1732template<class _Tp, class _Allocator,
1733         class = enable_if_t<__is_allocator<_Allocator>::value>>
1734unordered_multiset(initializer_list<_Tp>, typename allocator_traits<_Allocator>::size_type, _Allocator)
1735  -> unordered_multiset<_Tp, hash<_Tp>, equal_to<_Tp>, _Allocator>;
1736
1737template<class _Tp, class _Hash, class _Allocator,
1738         class = enable_if_t<!__is_allocator<_Hash>::value>,
1739         class = enable_if_t<!is_integral<_Hash>::value>,
1740         class = enable_if_t<__is_allocator<_Allocator>::value>>
1741unordered_multiset(initializer_list<_Tp>, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
1742  -> unordered_multiset<_Tp, _Hash, equal_to<_Tp>, _Allocator>;
1743#endif
1744
1745template <class _Value, class _Hash, class _Pred, class _Alloc>
1746unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1747        size_type __n, const hasher& __hf, const key_equal& __eql)
1748    : __table_(__hf, __eql)
1749{
1750    __table_.__rehash_multi(__n);
1751}
1752
1753template <class _Value, class _Hash, class _Pred, class _Alloc>
1754unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1755        size_type __n, const hasher& __hf, const key_equal& __eql,
1756        const allocator_type& __a)
1757    : __table_(__hf, __eql, __a)
1758{
1759    __table_.__rehash_multi(__n);
1760}
1761
1762template <class _Value, class _Hash, class _Pred, class _Alloc>
1763template <class _InputIterator>
1764unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1765        _InputIterator __first, _InputIterator __last)
1766{
1767    insert(__first, __last);
1768}
1769
1770template <class _Value, class _Hash, class _Pred, class _Alloc>
1771template <class _InputIterator>
1772unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1773        _InputIterator __first, _InputIterator __last, size_type __n,
1774        const hasher& __hf, const key_equal& __eql)
1775    : __table_(__hf, __eql)
1776{
1777    __table_.__rehash_multi(__n);
1778    insert(__first, __last);
1779}
1780
1781template <class _Value, class _Hash, class _Pred, class _Alloc>
1782template <class _InputIterator>
1783unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1784        _InputIterator __first, _InputIterator __last, size_type __n,
1785        const hasher& __hf, const key_equal& __eql, const allocator_type& __a)
1786    : __table_(__hf, __eql, __a)
1787{
1788    __table_.__rehash_multi(__n);
1789    insert(__first, __last);
1790}
1791
1792template <class _Value, class _Hash, class _Pred, class _Alloc>
1793inline
1794unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1795        const allocator_type& __a)
1796    : __table_(__a)
1797{
1798}
1799
1800template <class _Value, class _Hash, class _Pred, class _Alloc>
1801unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1802        const unordered_multiset& __u)
1803    : __table_(__u.__table_)
1804{
1805    __table_.__rehash_multi(__u.bucket_count());
1806    insert(__u.begin(), __u.end());
1807}
1808
1809template <class _Value, class _Hash, class _Pred, class _Alloc>
1810unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1811        const unordered_multiset& __u, const allocator_type& __a)
1812    : __table_(__u.__table_, __a)
1813{
1814    __table_.__rehash_multi(__u.bucket_count());
1815    insert(__u.begin(), __u.end());
1816}
1817
1818#ifndef _LIBCPP_CXX03_LANG
1819
1820template <class _Value, class _Hash, class _Pred, class _Alloc>
1821inline
1822unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1823        unordered_multiset&& __u)
1824    _NOEXCEPT_(is_nothrow_move_constructible<__table>::value)
1825    : __table_(_VSTD::move(__u.__table_))
1826{
1827}
1828
1829template <class _Value, class _Hash, class _Pred, class _Alloc>
1830unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1831        unordered_multiset&& __u, const allocator_type& __a)
1832    : __table_(_VSTD::move(__u.__table_), __a)
1833{
1834    if (__a != __u.get_allocator())
1835    {
1836        iterator __i = __u.begin();
1837        while (__u.size() != 0)
1838            __table_.__insert_multi(_VSTD::move(__u.__table_.remove(__i++)->__value_));
1839    }
1840}
1841
1842template <class _Value, class _Hash, class _Pred, class _Alloc>
1843unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1844        initializer_list<value_type> __il)
1845{
1846    insert(__il.begin(), __il.end());
1847}
1848
1849template <class _Value, class _Hash, class _Pred, class _Alloc>
1850unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1851        initializer_list<value_type> __il, size_type __n, const hasher& __hf,
1852        const key_equal& __eql)
1853    : __table_(__hf, __eql)
1854{
1855    __table_.__rehash_multi(__n);
1856    insert(__il.begin(), __il.end());
1857}
1858
1859template <class _Value, class _Hash, class _Pred, class _Alloc>
1860unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1861        initializer_list<value_type> __il, size_type __n, const hasher& __hf,
1862        const key_equal& __eql, const allocator_type& __a)
1863    : __table_(__hf, __eql, __a)
1864{
1865    __table_.__rehash_multi(__n);
1866    insert(__il.begin(), __il.end());
1867}
1868
1869template <class _Value, class _Hash, class _Pred, class _Alloc>
1870inline
1871unordered_multiset<_Value, _Hash, _Pred, _Alloc>&
1872unordered_multiset<_Value, _Hash, _Pred, _Alloc>::operator=(
1873        unordered_multiset&& __u)
1874    _NOEXCEPT_(is_nothrow_move_assignable<__table>::value)
1875{
1876    __table_ = _VSTD::move(__u.__table_);
1877    return *this;
1878}
1879
1880template <class _Value, class _Hash, class _Pred, class _Alloc>
1881inline
1882unordered_multiset<_Value, _Hash, _Pred, _Alloc>&
1883unordered_multiset<_Value, _Hash, _Pred, _Alloc>::operator=(
1884        initializer_list<value_type> __il)
1885{
1886    __table_.__assign_multi(__il.begin(), __il.end());
1887    return *this;
1888}
1889
1890#endif // _LIBCPP_CXX03_LANG
1891
1892template <class _Value, class _Hash, class _Pred, class _Alloc>
1893template <class _InputIterator>
1894inline
1895void
1896unordered_multiset<_Value, _Hash, _Pred, _Alloc>::insert(_InputIterator __first,
1897                                                         _InputIterator __last)
1898{
1899    for (; __first != __last; ++__first)
1900        __table_.__insert_multi(*__first);
1901}
1902
1903template <class _Value, class _Hash, class _Pred, class _Alloc>
1904inline _LIBCPP_INLINE_VISIBILITY
1905void
1906swap(unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __x,
1907     unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __y)
1908    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
1909{
1910    __x.swap(__y);
1911}
1912
1913#if _LIBCPP_STD_VER >= 20
1914template <class _Value, class _Hash, class _Pred, class _Alloc,
1915          class _Predicate>
1916inline _LIBCPP_INLINE_VISIBILITY
1917    typename unordered_multiset<_Value, _Hash, _Pred, _Alloc>::size_type
1918    erase_if(unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __c,
1919             _Predicate __pred) {
1920  return _VSTD::__libcpp_erase_if_container(__c, __pred);
1921}
1922#endif
1923
1924template <class _Value, class _Hash, class _Pred, class _Alloc>
1925_LIBCPP_HIDE_FROM_ABI bool
1926operator==(const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __x,
1927           const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __y)
1928{
1929    if (__x.size() != __y.size())
1930        return false;
1931    typedef typename unordered_multiset<_Value, _Hash, _Pred, _Alloc>::const_iterator
1932                                                                 const_iterator;
1933    typedef pair<const_iterator, const_iterator> _EqRng;
1934    for (const_iterator __i = __x.begin(), __ex = __x.end(); __i != __ex;)
1935    {
1936        _EqRng __xeq = __x.equal_range(*__i);
1937        _EqRng __yeq = __y.equal_range(*__i);
1938        if (_VSTD::distance(__xeq.first, __xeq.second) !=
1939            _VSTD::distance(__yeq.first, __yeq.second) ||
1940                  !_VSTD::is_permutation(__xeq.first, __xeq.second, __yeq.first))
1941            return false;
1942        __i = __xeq.second;
1943    }
1944    return true;
1945}
1946
1947#if _LIBCPP_STD_VER <= 17
1948
1949template <class _Value, class _Hash, class _Pred, class _Alloc>
1950inline _LIBCPP_INLINE_VISIBILITY
1951bool
1952operator!=(const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __x,
1953           const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __y)
1954{
1955    return !(__x == __y);
1956}
1957
1958#endif
1959
1960_LIBCPP_END_NAMESPACE_STD
1961
1962#if _LIBCPP_STD_VER >= 17
1963_LIBCPP_BEGIN_NAMESPACE_STD
1964namespace pmr {
1965template <class _KeyT, class _HashT = std::hash<_KeyT>, class _PredT = std::equal_to<_KeyT>>
1966using unordered_set _LIBCPP_AVAILABILITY_PMR = std::unordered_set<_KeyT, _HashT, _PredT, polymorphic_allocator<_KeyT>>;
1967
1968template <class _KeyT, class _HashT = std::hash<_KeyT>, class _PredT = std::equal_to<_KeyT>>
1969using unordered_multiset _LIBCPP_AVAILABILITY_PMR = std::unordered_multiset<_KeyT, _HashT, _PredT, polymorphic_allocator<_KeyT>>;
1970} // namespace pmr
1971_LIBCPP_END_NAMESPACE_STD
1972#endif
1973
1974#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
1975#  include <concepts>
1976#  include <cstdlib>
1977#  include <functional>
1978#  include <iterator>
1979#  include <type_traits>
1980#endif
1981
1982#endif // _LIBCPP_UNORDERED_SET
1983