xref: /llvm-project/libcxx/include/unordered_set (revision 0fa05456a8dc468961c33bd8149b157194672c71)
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// clang-format off
14
15/*
16
17    unordered_set synopsis
18
19#include <initializer_list>
20
21namespace std
22{
23
24template <class Value, class Hash = hash<Value>, class Pred = equal_to<Value>,
25          class Alloc = allocator<Value>>
26class unordered_set
27{
28public:
29    // types
30    typedef Value                                                      key_type;
31    typedef key_type                                                   value_type;
32    typedef Hash                                                       hasher;
33    typedef Pred                                                       key_equal;
34    typedef Alloc                                                      allocator_type;
35    typedef value_type&                                                reference;
36    typedef const value_type&                                          const_reference;
37    typedef typename allocator_traits<allocator_type>::pointer         pointer;
38    typedef typename allocator_traits<allocator_type>::const_pointer   const_pointer;
39    typedef typename allocator_traits<allocator_type>::size_type       size_type;
40    typedef typename allocator_traits<allocator_type>::difference_type difference_type;
41
42    typedef /unspecified/ iterator;
43    typedef /unspecified/ const_iterator;
44    typedef /unspecified/ local_iterator;
45    typedef /unspecified/ const_local_iterator;
46
47    typedef unspecified node_type unspecified;                            // C++17
48    typedef INSERT_RETURN_TYPE<iterator, node_type> insert_return_type;   // C++17
49
50    unordered_set()
51        noexcept(
52            is_nothrow_default_constructible<hasher>::value &&
53            is_nothrow_default_constructible<key_equal>::value &&
54            is_nothrow_default_constructible<allocator_type>::value);
55    explicit unordered_set(size_type n, const hasher& hf = hasher(),
56                           const key_equal& eql = key_equal(),
57                           const allocator_type& a = allocator_type());
58    template <class InputIterator>
59        unordered_set(InputIterator f, InputIterator l,
60                      size_type n = 0, const hasher& hf = hasher(),
61                      const key_equal& eql = key_equal(),
62                      const allocator_type& a = allocator_type());
63    template<container-compatible-range<value_type> R>
64      unordered_set(from_range_t, R&& rg, size_type n = see below,
65        const hasher& hf = hasher(), const key_equal& eql = key_equal(),
66        const allocator_type& a = allocator_type()); // C++23
67    explicit unordered_set(const allocator_type&);
68    unordered_set(const unordered_set&);
69    unordered_set(const unordered_set&, const Allocator&);
70    unordered_set(unordered_set&&)
71        noexcept(
72            is_nothrow_move_constructible<hasher>::value &&
73            is_nothrow_move_constructible<key_equal>::value &&
74            is_nothrow_move_constructible<allocator_type>::value);
75    unordered_set(unordered_set&&, const Allocator&);
76    unordered_set(initializer_list<value_type>, size_type n = 0,
77                  const hasher& hf = hasher(), const key_equal& eql = key_equal(),
78                  const allocator_type& a = allocator_type());
79    unordered_set(size_type n, const allocator_type& a); // C++14
80    unordered_set(size_type n, const hasher& hf, const allocator_type& a); // C++14
81    template <class InputIterator>
82      unordered_set(InputIterator f, InputIterator l, size_type n, const allocator_type& a); // C++14
83    template <class InputIterator>
84      unordered_set(InputIterator f, InputIterator l, size_type n,
85                    const hasher& hf,  const allocator_type& a); // C++14
86    template<container-compatible-range<value_type> R>
87      unordered_set(from_range_t, R&& rg, size_type n, const allocator_type& a)
88        : unordered_set(from_range, std::forward<R>(rg), n, hasher(), key_equal(), a) { } // C++23
89    template<container-compatible-range<value_type> R>
90      unordered_set(from_range_t, R&& rg, size_type n, const hasher& hf, const allocator_type& a)
91        : unordered_set(from_range, std::forward<R>(rg), n, hf, key_equal(), a) { }       // C++23
92    unordered_set(initializer_list<value_type> il, size_type n, const allocator_type& a); // C++14
93    unordered_set(initializer_list<value_type> il, size_type n,
94                  const hasher& hf,  const allocator_type& a); // C++14
95    ~unordered_set();
96    unordered_set& operator=(const unordered_set&);
97    unordered_set& operator=(unordered_set&&)
98        noexcept(
99            allocator_type::propagate_on_container_move_assignment::value &&
100            is_nothrow_move_assignable<allocator_type>::value &&
101            is_nothrow_move_assignable<hasher>::value &&
102            is_nothrow_move_assignable<key_equal>::value);
103    unordered_set& operator=(initializer_list<value_type>);
104
105    allocator_type get_allocator() const noexcept;
106
107    bool      empty() const noexcept;
108    size_type size() const noexcept;
109    size_type max_size() const noexcept;
110
111    iterator       begin() noexcept;
112    iterator       end() noexcept;
113    const_iterator begin()  const noexcept;
114    const_iterator end()    const noexcept;
115    const_iterator cbegin() const noexcept;
116    const_iterator cend()   const noexcept;
117
118    template <class... Args>
119        pair<iterator, bool> emplace(Args&&... args);
120    template <class... Args>
121        iterator emplace_hint(const_iterator position, Args&&... args);
122    pair<iterator, bool> insert(const value_type& obj);
123    pair<iterator, bool> insert(value_type&& obj);
124    iterator insert(const_iterator hint, const value_type& obj);
125    iterator insert(const_iterator hint, value_type&& obj);
126    template <class InputIterator>
127        void insert(InputIterator first, InputIterator last);
128    template<container-compatible-range<value_type> R>
129      void insert_range(R&& rg);                                      // C++23
130    void insert(initializer_list<value_type>);
131
132    node_type extract(const_iterator position);                       // C++17
133    node_type extract(const key_type& x);                             // C++17
134    insert_return_type insert(node_type&& nh);                        // C++17
135    iterator           insert(const_iterator hint, node_type&& nh);   // C++17
136
137    iterator erase(const_iterator position);
138    iterator erase(iterator position);  // C++14
139    size_type erase(const key_type& k);
140    iterator erase(const_iterator first, const_iterator last);
141    void clear() noexcept;
142
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_set<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    template<class H2, class P2>
150      void merge(unordered_multiset<Key, H2, P2, Allocator>&& source);   // C++17
151
152    void swap(unordered_set&)
153       noexcept(allocator_traits<Allocator>::is_always_equal::value &&
154                 noexcept(swap(declval<hasher&>(), declval<hasher&>())) &&
155                 noexcept(swap(declval<key_equal&>(), declval<key_equal&>()))); // C++17
156
157    hasher hash_function() const;
158    key_equal key_eq() const;
159
160    iterator       find(const key_type& k);
161    const_iterator find(const key_type& k) const;
162    template<typename K>
163        iterator find(const K& x);              // C++20
164    template<typename K>
165        const_iterator find(const K& x) const;  // C++20
166    size_type count(const key_type& k) const;
167    template<typename K>
168        size_type count(const K& k) const; // C++20
169    bool contains(const key_type& k) const; // C++20
170    template<typename K>
171        bool contains(const K& k) const; // C++20
172    pair<iterator, iterator>             equal_range(const key_type& k);
173    pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
174    template<typename K>
175        pair<iterator, iterator>             equal_range(const K& k); // C++20
176    template<typename K>
177        pair<const_iterator, const_iterator> equal_range(const K& k) const; // C++20
178
179    size_type bucket_count() const noexcept;
180    size_type max_bucket_count() const noexcept;
181
182    size_type bucket_size(size_type n) const;
183    size_type bucket(const key_type& k) const;
184
185    local_iterator       begin(size_type n);
186    local_iterator       end(size_type n);
187    const_local_iterator begin(size_type n) const;
188    const_local_iterator end(size_type n) const;
189    const_local_iterator cbegin(size_type n) const;
190    const_local_iterator cend(size_type n) const;
191
192    float load_factor() const noexcept;
193    float max_load_factor() const noexcept;
194    void max_load_factor(float z);
195    void rehash(size_type n);
196    void reserve(size_type n);
197};
198
199template<class InputIterator,
200    class Hash = hash<typename iterator_traits<InputIterator>::value_type>,
201    class Pred = equal_to<typename iterator_traits<InputIterator>::value_type>,
202    class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
203unordered_set(InputIterator, InputIterator, typename see below::size_type = see below,
204    Hash = Hash(), Pred = Pred(), Allocator = Allocator())
205  -> unordered_set<typename iterator_traits<InputIterator>::value_type,
206        Hash, Pred, Allocator>; // C++17
207
208template<ranges::input_range R,
209         class Hash = hash<ranges::range_value_t<R>>,
210         class Pred = equal_to<ranges::range_value_t<R>>,
211         class Allocator = allocator<ranges::range_value_t<R>>>
212  unordered_set(from_range_t, R&&, typename see below::size_type = see below, Hash = Hash(), Pred = Pred(), Allocator = Allocator())
213    -> unordered_set<ranges::range_value_t<R>, Hash, Pred, Allocator>; // C++23
214
215template<class T, class Hash = hash<T>,
216          class Pred = equal_to<T>, class Allocator = allocator<T>>
217unordered_set(initializer_list<T>, typename see below::size_type = see below,
218    Hash = Hash(), Pred = Pred(), Allocator = Allocator())
219  -> unordered_set<T, Hash, Pred, Allocator>; // C++17
220
221template<class InputIterator,  class Allocator>
222unordered_set(InputIterator, InputIterator, typename see below::size_type, Allocator)
223  -> unordered_set<typename iterator_traits<InputIterator>::value_type,
224        hash<typename iterator_traits<InputIterator>::value_type>,
225        equal_to<typename iterator_traits<InputIterator>::value_type>,
226        Allocator>; // C++17
227
228template<class InputIterator, class Hash, class Allocator>
229unordered_set(InputIterator, InputIterator, typename see below::size_type,
230    Hash, Allocator)
231  -> unordered_set<typename iterator_traits<InputIterator>::value_type, Hash,
232        equal_to<typename iterator_traits<InputIterator>::value_type>,
233        Allocator>; // C++17
234
235template<ranges::input_range R, class Allocator>
236  unordered_set(from_range_t, R&&, typename see below::size_type, Allocator)
237    -> unordered_set<ranges::range_value_t<R>, hash<ranges::range_value_t<R>>,
238                      equal_to<ranges::range_value_t<R>>, Allocator>; // C++23
239
240template<ranges::input_range R, class Allocator>
241  unordered_set(from_range_t, R&&, Allocator)
242    -> unordered_set<ranges::range_value_t<R>, hash<ranges::range_value_t<R>>,
243                      equal_to<ranges::range_value_t<R>>, Allocator>; // C++23
244
245template<ranges::input_range R, class Hash, class Allocator>
246  unordered_set(from_range_t, R&&, typename see below::size_type, Hash, Allocator)
247    -> unordered_set<ranges::range_value_t<R>, Hash,
248                      equal_to<ranges::range_value_t<R>>, Allocator>; // C++23
249
250template<class T, class Allocator>
251unordered_set(initializer_list<T>, typename see below::size_type, Allocator)
252  -> unordered_set<T, hash<T>, equal_to<T>, Allocator>; // C++17
253
254template<class T, class Hash, class Allocator>
255unordered_set(initializer_list<T>, typename see below::size_type, Hash, Allocator)
256  -> unordered_set<T, Hash, equal_to<T>, Allocator>; // C++17
257
258template <class Value, class Hash, class Pred, class Alloc>
259    void swap(unordered_set<Value, Hash, Pred, Alloc>& x,
260              unordered_set<Value, Hash, Pred, Alloc>& y)
261              noexcept(noexcept(x.swap(y)));
262
263template <class Value, class Hash, class Pred, class Alloc>
264    bool
265    operator==(const unordered_set<Value, Hash, Pred, Alloc>& x,
266               const unordered_set<Value, Hash, Pred, Alloc>& y);
267
268template <class Value, class Hash, class Pred, class Alloc>
269    bool
270    operator!=(const unordered_set<Value, Hash, Pred, Alloc>& x,
271               const unordered_set<Value, Hash, Pred, Alloc>& y); // removed in C++20
272
273template <class Value, class Hash = hash<Value>, class Pred = equal_to<Value>,
274          class Alloc = allocator<Value>>
275class unordered_multiset
276{
277public:
278    // types
279    typedef Value                                                      key_type;
280    typedef key_type                                                   value_type;
281    typedef Hash                                                       hasher;
282    typedef Pred                                                       key_equal;
283    typedef Alloc                                                      allocator_type;
284    typedef value_type&                                                reference;
285    typedef const value_type&                                          const_reference;
286    typedef typename allocator_traits<allocator_type>::pointer         pointer;
287    typedef typename allocator_traits<allocator_type>::const_pointer   const_pointer;
288    typedef typename allocator_traits<allocator_type>::size_type       size_type;
289    typedef typename allocator_traits<allocator_type>::difference_type difference_type;
290
291    typedef /unspecified/ iterator;
292    typedef /unspecified/ const_iterator;
293    typedef /unspecified/ local_iterator;
294    typedef /unspecified/ const_local_iterator;
295
296    typedef unspecified node_type unspecified;   // C++17
297
298    unordered_multiset()
299        noexcept(
300            is_nothrow_default_constructible<hasher>::value &&
301            is_nothrow_default_constructible<key_equal>::value &&
302            is_nothrow_default_constructible<allocator_type>::value);
303    explicit unordered_multiset(size_type n, const hasher& hf = hasher(),
304                           const key_equal& eql = key_equal(),
305                           const allocator_type& a = allocator_type());
306    template <class InputIterator>
307        unordered_multiset(InputIterator f, InputIterator l,
308                      size_type n = 0, const hasher& hf = hasher(),
309                      const key_equal& eql = key_equal(),
310                      const allocator_type& a = allocator_type());
311    template<container-compatible-range<value_type> R>
312      unordered_multiset(from_range_t, R&& rg, size_type n = see below,
313        const hasher& hf = hasher(), const key_equal& eql = key_equal(),
314        const allocator_type& a = allocator_type()); // C++23
315    explicit unordered_multiset(const allocator_type&);
316    unordered_multiset(const unordered_multiset&);
317    unordered_multiset(const unordered_multiset&, const Allocator&);
318    unordered_multiset(unordered_multiset&&)
319        noexcept(
320            is_nothrow_move_constructible<hasher>::value &&
321            is_nothrow_move_constructible<key_equal>::value &&
322            is_nothrow_move_constructible<allocator_type>::value);
323    unordered_multiset(unordered_multiset&&, const Allocator&);
324    unordered_multiset(initializer_list<value_type>, size_type n = /see below/,
325                  const hasher& hf = hasher(), const key_equal& eql = key_equal(),
326                  const allocator_type& a = allocator_type());
327    unordered_multiset(size_type n, const allocator_type& a); // C++14
328    unordered_multiset(size_type n, const hasher& hf, const allocator_type& a); // C++14
329    template <class InputIterator>
330      unordered_multiset(InputIterator f, InputIterator l, size_type n, const allocator_type& a); // C++14
331    template <class InputIterator>
332      unordered_multiset(InputIterator f, InputIterator l, size_type n,
333                         const hasher& hf, const allocator_type& a); // C++14
334    template<container-compatible-range<value_type> R>
335      unordered_multiset(from_range_t, R&& rg, size_type n, const allocator_type& a)
336        : unordered_multiset(from_range, std::forward<R>(rg), n, hasher(), key_equal(), a) { } // C++23
337    template<container-compatible-range<value_type> R>
338      unordered_multiset(from_range_t, R&& rg, size_type n, const hasher& hf, const allocator_type& a)
339        : unordered_multiset(from_range, std::forward<R>(rg), n, hf, key_equal(), a) { }       // C++23
340    unordered_multiset(initializer_list<value_type> il, size_type n, const allocator_type& a); // C++14
341    unordered_multiset(initializer_list<value_type> il, size_type n,
342                       const hasher& hf,  const allocator_type& a); // C++14
343    ~unordered_multiset();
344    unordered_multiset& operator=(const unordered_multiset&);
345    unordered_multiset& operator=(unordered_multiset&&)
346        noexcept(
347            allocator_type::propagate_on_container_move_assignment::value &&
348            is_nothrow_move_assignable<allocator_type>::value &&
349            is_nothrow_move_assignable<hasher>::value &&
350            is_nothrow_move_assignable<key_equal>::value);
351    unordered_multiset& operator=(initializer_list<value_type>);
352
353    allocator_type get_allocator() const noexcept;
354
355    bool      empty() const noexcept;
356    size_type size() const noexcept;
357    size_type max_size() const noexcept;
358
359    iterator       begin() noexcept;
360    iterator       end() noexcept;
361    const_iterator begin()  const noexcept;
362    const_iterator end()    const noexcept;
363    const_iterator cbegin() const noexcept;
364    const_iterator cend()   const noexcept;
365
366    template <class... Args>
367        iterator emplace(Args&&... args);
368    template <class... Args>
369        iterator emplace_hint(const_iterator position, Args&&... args);
370    iterator insert(const value_type& obj);
371    iterator insert(value_type&& obj);
372    iterator insert(const_iterator hint, const value_type& obj);
373    iterator insert(const_iterator hint, value_type&& obj);
374    template <class InputIterator>
375        void insert(InputIterator first, InputIterator last);
376    template<container-compatible-range<value_type> R>
377      void insert_range(R&& rg);                            // C++23
378    void insert(initializer_list<value_type>);
379
380    node_type extract(const_iterator position);             // C++17
381    node_type extract(const key_type& x);                   // C++17
382    iterator insert(node_type&& nh);                        // C++17
383    iterator insert(const_iterator hint, node_type&& nh);   // C++17
384
385    iterator erase(const_iterator position);
386    iterator erase(iterator position);  // C++14
387    size_type erase(const key_type& k);
388    iterator erase(const_iterator first, const_iterator last);
389    void clear() noexcept;
390
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_multiset<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    template<class H2, class P2>
398      void merge(unordered_set<Key, H2, P2, Allocator>&& source);        // C++17
399
400    void swap(unordered_multiset&)
401       noexcept(allocator_traits<Allocator>::is_always_equal::value &&
402                 noexcept(swap(declval<hasher&>(), declval<hasher&>())) &&
403                 noexcept(swap(declval<key_equal&>(), declval<key_equal&>()))); // C++17
404
405    hasher hash_function() const;
406    key_equal key_eq() const;
407
408    iterator       find(const key_type& k);
409    const_iterator find(const key_type& k) const;
410    template<typename K>
411        iterator find(const K& x);              // C++20
412    template<typename K>
413        const_iterator find(const K& x) const;  // C++20
414    size_type count(const key_type& k) const;
415    template<typename K>
416        size_type count(const K& k) const; // C++20
417    bool contains(const key_type& k) const; // C++20
418    template<typename K>
419        bool contains(const K& k) const; // C++20
420    pair<iterator, iterator>             equal_range(const key_type& k);
421    pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
422    template<typename K>
423        pair<iterator, iterator>             equal_range(const K& k); // C++20
424    template<typename K>
425        pair<const_iterator, const_iterator> equal_range(const K& k) const; // C++20
426
427    size_type bucket_count() const noexcept;
428    size_type max_bucket_count() const noexcept;
429
430    size_type bucket_size(size_type n) const;
431    size_type bucket(const key_type& k) const;
432
433    local_iterator       begin(size_type n);
434    local_iterator       end(size_type n);
435    const_local_iterator begin(size_type n) const;
436    const_local_iterator end(size_type n) const;
437    const_local_iterator cbegin(size_type n) const;
438    const_local_iterator cend(size_type n) const;
439
440    float load_factor() const noexcept;
441    float max_load_factor() const noexcept;
442    void max_load_factor(float z);
443    void rehash(size_type n);
444    void reserve(size_type n);
445};
446
447template<class InputIterator,
448    class Hash = hash<typename iterator_traits<InputIterator>::value_type>,
449    class Pred = equal_to<typename iterator_traits<InputIterator>::value_type>,
450    class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
451unordered_multiset(InputIterator, InputIterator, see below::size_type = see below,
452    Hash = Hash(), Pred = Pred(), Allocator = Allocator())
453  -> unordered_multiset<typename iterator_traits<InputIterator>::value_type,
454        Hash, Pred, Allocator>; // C++17
455
456template<ranges::input_range R,
457         class Hash = hash<ranges::range_value_t<R>>,
458         class Pred = equal_to<ranges::range_value_t<R>>,
459         class Allocator = allocator<ranges::range_value_t<R>>>
460  unordered_multiset(from_range_t, R&&, typename see below::size_type = see below, Hash = Hash(), Pred = Pred(), Allocator = Allocator())
461    -> unordered_multiset<ranges::range_value_t<R>, Hash, Pred, Allocator>; // C++23
462
463template<class T, class Hash = hash<T>,
464          class Pred = equal_to<T>, class Allocator = allocator<T>>
465unordered_multiset(initializer_list<T>, typename see below::size_type = see below,
466    Hash = Hash(), Pred = Pred(), Allocator = Allocator())
467  -> unordered_multiset<T, Hash, Pred, Allocator>; // C++17
468
469template<class InputIterator,  class Allocator>
470unordered_multiset(InputIterator, InputIterator, typename see below::size_type, Allocator)
471  -> unordered_multiset<typename iterator_traits<InputIterator>::value_type,
472        hash<typename iterator_traits<InputIterator>::value_type>,
473        equal_to<typename iterator_traits<InputIterator>::value_type>,
474        Allocator>; // C++17
475
476template<class InputIterator,  class Hash, class Allocator>
477unordered_multiset(InputIterator, InputIterator, typename see below::size_type,
478    Hash, Allocator)
479  -> unordered_multiset<typename iterator_traits<InputIterator>::value_type, Hash,
480        equal_to<typename iterator_traits<InputIterator>::value_type>, Allocator>; // C++17
481
482template<ranges::input_range R, class Allocator>
483  unordered_multiset(from_range_t, R&&, typename see below::size_type, Allocator)
484    -> unordered_multiset<ranges::range_value_t<R>, hash<ranges::range_value_t<R>>,
485                      equal_to<ranges::range_value_t<R>>, Allocator>; // C++23
486
487template<ranges::input_range R, class Allocator>
488  unordered_multiset(from_range_t, R&&, Allocator)
489    -> unordered_multiset<ranges::range_value_t<R>, hash<ranges::range_value_t<R>>,
490                      equal_to<ranges::range_value_t<R>>, Allocator>; // C++23
491
492template<ranges::input_range R, class Hash, class Allocator>
493  unordered_multiset(from_range_t, R&&, typename see below::size_type, Hash, Allocator)
494    -> unordered_multiset<ranges::range_value_t<R>, Hash,
495                      equal_to<ranges::range_value_t<R>>, Allocator>; // C++23
496
497template<class T, class Allocator>
498unordered_multiset(initializer_list<T>, typename see below::size_type, Allocator)
499  -> unordered_multiset<T, hash<T>, equal_to<T>, Allocator>; // C++17
500
501template<class T, class Hash, class Allocator>
502unordered_multiset(initializer_list<T>, typename see below::size_type, Hash, Allocator)
503  -> unordered_multiset<T, Hash, equal_to<T>, Allocator>; // C++17
504
505template <class Value, class Hash, class Pred, class Alloc>
506    void swap(unordered_multiset<Value, Hash, Pred, Alloc>& x,
507              unordered_multiset<Value, Hash, Pred, Alloc>& y)
508              noexcept(noexcept(x.swap(y)));
509
510template <class K, class T, class H, class P, class A, class Predicate>
511    typename unordered_set<K, T, H, P, A>::size_type
512    erase_if(unordered_set<K, T, H, P, A>& c, Predicate pred);       // C++20
513
514template <class K, class T, class H, class P, class A, class Predicate>
515    typename unordered_multiset<K, T, H, P, A>::size_type
516    erase_if(unordered_multiset<K, T, H, P, A>& c, Predicate pred);  // C++20
517
518
519template <class Value, class Hash, class Pred, class Alloc>
520    bool
521    operator==(const unordered_multiset<Value, Hash, Pred, Alloc>& x,
522               const unordered_multiset<Value, Hash, Pred, Alloc>& y);
523
524template <class Value, class Hash, class Pred, class Alloc>
525    bool
526    operator!=(const unordered_multiset<Value, Hash, Pred, Alloc>& x,
527               const unordered_multiset<Value, Hash, Pred, Alloc>& y); // removed in C++20
528}  // std
529
530*/
531
532// clang-format on
533
534#if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
535#  include <__cxx03/unordered_set>
536#else
537#  include <__algorithm/is_permutation.h>
538#  include <__assert>
539#  include <__config>
540#  include <__functional/hash.h>
541#  include <__functional/is_transparent.h>
542#  include <__functional/operations.h>
543#  include <__hash_table>
544#  include <__iterator/distance.h>
545#  include <__iterator/erase_if_container.h>
546#  include <__iterator/iterator_traits.h>
547#  include <__iterator/ranges_iterator_traits.h>
548#  include <__memory/addressof.h>
549#  include <__memory/allocator.h>
550#  include <__memory/allocator_traits.h>
551#  include <__memory_resource/polymorphic_allocator.h>
552#  include <__node_handle>
553#  include <__ranges/concepts.h>
554#  include <__ranges/container_compatible_range.h>
555#  include <__ranges/from_range.h>
556#  include <__type_traits/container_traits.h>
557#  include <__type_traits/enable_if.h>
558#  include <__type_traits/invoke.h>
559#  include <__type_traits/is_allocator.h>
560#  include <__type_traits/is_integral.h>
561#  include <__type_traits/is_nothrow_assignable.h>
562#  include <__type_traits/is_nothrow_constructible.h>
563#  include <__type_traits/is_same.h>
564#  include <__type_traits/is_swappable.h>
565#  include <__type_traits/type_identity.h>
566#  include <__utility/forward.h>
567#  include <__utility/move.h>
568#  include <__utility/pair.h>
569#  include <version>
570
571// standard-mandated includes
572
573// [iterator.range]
574#  include <__iterator/access.h>
575#  include <__iterator/data.h>
576#  include <__iterator/empty.h>
577#  include <__iterator/reverse_access.h>
578#  include <__iterator/size.h>
579
580// [unord.set.syn]
581#  include <compare>
582#  include <initializer_list>
583
584#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
585#    pragma GCC system_header
586#  endif
587
588_LIBCPP_PUSH_MACROS
589#  include <__undef_macros>
590
591_LIBCPP_BEGIN_NAMESPACE_STD
592
593template <class _Value, class _Hash, class _Pred, class _Alloc>
594class unordered_multiset;
595
596template <class _Value, class _Hash = hash<_Value>, class _Pred = equal_to<_Value>, class _Alloc = allocator<_Value> >
597class _LIBCPP_TEMPLATE_VIS unordered_set {
598public:
599  // types
600  typedef _Value key_type;
601  typedef key_type value_type;
602  typedef __type_identity_t<_Hash> hasher;
603  typedef __type_identity_t<_Pred> key_equal;
604  typedef __type_identity_t<_Alloc> allocator_type;
605  typedef value_type& reference;
606  typedef const value_type& const_reference;
607  static_assert(__check_valid_allocator<allocator_type>::value, "");
608  static_assert(is_same<value_type, typename allocator_type::value_type>::value,
609                "Allocator::value_type must be same type as value_type");
610
611private:
612  typedef __hash_table<value_type, hasher, key_equal, allocator_type> __table;
613
614  __table __table_;
615
616public:
617  typedef typename __table::pointer pointer;
618  typedef typename __table::const_pointer const_pointer;
619  typedef typename __table::size_type size_type;
620  typedef typename __table::difference_type difference_type;
621
622  typedef typename __table::const_iterator iterator;
623  typedef typename __table::const_iterator const_iterator;
624  typedef typename __table::const_local_iterator local_iterator;
625  typedef typename __table::const_local_iterator const_local_iterator;
626
627#  if _LIBCPP_STD_VER >= 17
628  typedef __set_node_handle<typename __table::__node, allocator_type> node_type;
629  typedef __insert_return_type<iterator, node_type> insert_return_type;
630#  endif
631
632  template <class _Value2, class _Hash2, class _Pred2, class _Alloc2>
633  friend class _LIBCPP_TEMPLATE_VIS unordered_set;
634  template <class _Value2, class _Hash2, class _Pred2, class _Alloc2>
635  friend class _LIBCPP_TEMPLATE_VIS unordered_multiset;
636
637  _LIBCPP_HIDE_FROM_ABI unordered_set() _NOEXCEPT_(is_nothrow_default_constructible<__table>::value) {}
638  explicit _LIBCPP_HIDE_FROM_ABI
639  unordered_set(size_type __n, const hasher& __hf = hasher(), const key_equal& __eql = key_equal());
640#  if _LIBCPP_STD_VER >= 14
641  inline _LIBCPP_HIDE_FROM_ABI unordered_set(size_type __n, const allocator_type& __a)
642      : unordered_set(__n, hasher(), key_equal(), __a) {}
643  inline _LIBCPP_HIDE_FROM_ABI unordered_set(size_type __n, const hasher& __hf, const allocator_type& __a)
644      : unordered_set(__n, __hf, key_equal(), __a) {}
645#  endif
646  _LIBCPP_HIDE_FROM_ABI
647  unordered_set(size_type __n, const hasher& __hf, const key_equal& __eql, const allocator_type& __a);
648  template <class _InputIterator>
649  _LIBCPP_HIDE_FROM_ABI unordered_set(_InputIterator __first, _InputIterator __last);
650  template <class _InputIterator>
651  _LIBCPP_HIDE_FROM_ABI
652  unordered_set(_InputIterator __first,
653                _InputIterator __last,
654                size_type __n,
655                const hasher& __hf     = hasher(),
656                const key_equal& __eql = key_equal());
657  template <class _InputIterator>
658  _LIBCPP_HIDE_FROM_ABI unordered_set(
659      _InputIterator __first,
660      _InputIterator __last,
661      size_type __n,
662      const hasher& __hf,
663      const key_equal& __eql,
664      const allocator_type& __a);
665
666#  if _LIBCPP_STD_VER >= 23
667  template <_ContainerCompatibleRange<value_type> _Range>
668  _LIBCPP_HIDE_FROM_ABI unordered_set(
669      from_range_t,
670      _Range&& __range,
671      size_type __n             = /*implementation-defined*/ 0,
672      const hasher& __hf        = hasher(),
673      const key_equal& __eql    = key_equal(),
674      const allocator_type& __a = allocator_type())
675      : __table_(__hf, __eql, __a) {
676    if (__n > 0) {
677      __table_.__rehash_unique(__n);
678    }
679    insert_range(std::forward<_Range>(__range));
680  }
681#  endif
682
683#  if _LIBCPP_STD_VER >= 14
684  template <class _InputIterator>
685  inline _LIBCPP_HIDE_FROM_ABI
686  unordered_set(_InputIterator __first, _InputIterator __last, size_type __n, const allocator_type& __a)
687      : unordered_set(__first, __last, __n, hasher(), key_equal(), __a) {}
688  template <class _InputIterator>
689  _LIBCPP_HIDE_FROM_ABI unordered_set(
690      _InputIterator __first, _InputIterator __last, size_type __n, const hasher& __hf, const allocator_type& __a)
691      : unordered_set(__first, __last, __n, __hf, key_equal(), __a) {}
692#  endif
693
694#  if _LIBCPP_STD_VER >= 23
695  template <_ContainerCompatibleRange<value_type> _Range>
696  _LIBCPP_HIDE_FROM_ABI unordered_set(from_range_t, _Range&& __range, size_type __n, const allocator_type& __a)
697      : unordered_set(from_range, std::forward<_Range>(__range), __n, hasher(), key_equal(), __a) {}
698
699  template <_ContainerCompatibleRange<value_type> _Range>
700  _LIBCPP_HIDE_FROM_ABI
701  unordered_set(from_range_t, _Range&& __range, size_type __n, const hasher& __hf, const allocator_type& __a)
702      : unordered_set(from_range, std::forward<_Range>(__range), __n, __hf, key_equal(), __a) {}
703#  endif
704
705  _LIBCPP_HIDE_FROM_ABI explicit unordered_set(const allocator_type& __a);
706  _LIBCPP_HIDE_FROM_ABI unordered_set(const unordered_set& __u);
707  _LIBCPP_HIDE_FROM_ABI unordered_set(const unordered_set& __u, const allocator_type& __a);
708#  ifndef _LIBCPP_CXX03_LANG
709  _LIBCPP_HIDE_FROM_ABI unordered_set(unordered_set&& __u) _NOEXCEPT_(is_nothrow_move_constructible<__table>::value);
710  _LIBCPP_HIDE_FROM_ABI unordered_set(unordered_set&& __u, const allocator_type& __a);
711  _LIBCPP_HIDE_FROM_ABI unordered_set(initializer_list<value_type> __il);
712  _LIBCPP_HIDE_FROM_ABI
713  unordered_set(initializer_list<value_type> __il,
714                size_type __n,
715                const hasher& __hf     = hasher(),
716                const key_equal& __eql = key_equal());
717  _LIBCPP_HIDE_FROM_ABI unordered_set(
718      initializer_list<value_type> __il,
719      size_type __n,
720      const hasher& __hf,
721      const key_equal& __eql,
722      const allocator_type& __a);
723#    if _LIBCPP_STD_VER >= 14
724  inline _LIBCPP_HIDE_FROM_ABI
725  unordered_set(initializer_list<value_type> __il, size_type __n, const allocator_type& __a)
726      : unordered_set(__il, __n, hasher(), key_equal(), __a) {}
727  inline _LIBCPP_HIDE_FROM_ABI
728  unordered_set(initializer_list<value_type> __il, size_type __n, const hasher& __hf, const allocator_type& __a)
729      : unordered_set(__il, __n, __hf, key_equal(), __a) {}
730#    endif
731#  endif // _LIBCPP_CXX03_LANG
732  _LIBCPP_HIDE_FROM_ABI ~unordered_set() {
733    static_assert(sizeof(std::__diagnose_unordered_container_requirements<_Value, _Hash, _Pred>(0)), "");
734  }
735
736  _LIBCPP_HIDE_FROM_ABI unordered_set& operator=(const unordered_set& __u) {
737    __table_ = __u.__table_;
738    return *this;
739  }
740#  ifndef _LIBCPP_CXX03_LANG
741  _LIBCPP_HIDE_FROM_ABI unordered_set& operator=(unordered_set&& __u)
742      _NOEXCEPT_(is_nothrow_move_assignable<__table>::value);
743  _LIBCPP_HIDE_FROM_ABI unordered_set& operator=(initializer_list<value_type> __il);
744#  endif // _LIBCPP_CXX03_LANG
745
746  _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT {
747    return allocator_type(__table_.__node_alloc());
748  }
749
750  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool empty() const _NOEXCEPT { return __table_.size() == 0; }
751  _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return __table_.size(); }
752  _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT { return __table_.max_size(); }
753
754  _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return __table_.begin(); }
755  _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT { return __table_.end(); }
756  _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return __table_.begin(); }
757  _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return __table_.end(); }
758  _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT { return __table_.begin(); }
759  _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT { return __table_.end(); }
760
761#  ifndef _LIBCPP_CXX03_LANG
762  template <class... _Args>
763  _LIBCPP_HIDE_FROM_ABI pair<iterator, bool> emplace(_Args&&... __args) {
764    return __table_.__emplace_unique(std::forward<_Args>(__args)...);
765  }
766  template <class... _Args>
767  _LIBCPP_HIDE_FROM_ABI iterator emplace_hint(const_iterator, _Args&&... __args) {
768    return __table_.__emplace_unique(std::forward<_Args>(__args)...).first;
769  }
770
771  _LIBCPP_HIDE_FROM_ABI pair<iterator, bool> insert(value_type&& __x) {
772    return __table_.__insert_unique(std::move(__x));
773  }
774  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator, value_type&& __x) { return insert(std::move(__x)).first; }
775
776  _LIBCPP_HIDE_FROM_ABI void insert(initializer_list<value_type> __il) { insert(__il.begin(), __il.end()); }
777#  endif // _LIBCPP_CXX03_LANG
778  _LIBCPP_HIDE_FROM_ABI pair<iterator, bool> insert(const value_type& __x) { return __table_.__insert_unique(__x); }
779
780  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator, const value_type& __x) { return insert(__x).first; }
781  template <class _InputIterator>
782  _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __first, _InputIterator __last);
783
784#  if _LIBCPP_STD_VER >= 23
785  template <_ContainerCompatibleRange<value_type> _Range>
786  _LIBCPP_HIDE_FROM_ABI void insert_range(_Range&& __range) {
787    for (auto&& __element : __range) {
788      __table_.__insert_unique(std::forward<decltype(__element)>(__element));
789    }
790  }
791#  endif
792
793  _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __p) { return __table_.erase(__p); }
794  _LIBCPP_HIDE_FROM_ABI size_type erase(const key_type& __k) { return __table_.__erase_unique(__k); }
795  _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __first, const_iterator __last) {
796    return __table_.erase(__first, __last);
797  }
798  _LIBCPP_HIDE_FROM_ABI void clear() _NOEXCEPT { __table_.clear(); }
799
800#  if _LIBCPP_STD_VER >= 17
801  _LIBCPP_HIDE_FROM_ABI insert_return_type insert(node_type&& __nh) {
802    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__nh.empty() || __nh.get_allocator() == get_allocator(),
803                                        "node_type with incompatible allocator passed to unordered_set::insert()");
804    return __table_.template __node_handle_insert_unique< node_type, insert_return_type>(std::move(__nh));
805  }
806  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __h, node_type&& __nh) {
807    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__nh.empty() || __nh.get_allocator() == get_allocator(),
808                                        "node_type with incompatible allocator passed to unordered_set::insert()");
809    return __table_.template __node_handle_insert_unique<node_type>(__h, std::move(__nh));
810  }
811  _LIBCPP_HIDE_FROM_ABI node_type extract(key_type const& __key) {
812    return __table_.template __node_handle_extract<node_type>(__key);
813  }
814  _LIBCPP_HIDE_FROM_ABI node_type extract(const_iterator __it) {
815    return __table_.template __node_handle_extract<node_type>(__it);
816  }
817
818  template <class _H2, class _P2>
819  _LIBCPP_HIDE_FROM_ABI void merge(unordered_set<key_type, _H2, _P2, allocator_type>& __source) {
820    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
821        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
822    __table_.__node_handle_merge_unique(__source.__table_);
823  }
824  template <class _H2, class _P2>
825  _LIBCPP_HIDE_FROM_ABI void merge(unordered_set<key_type, _H2, _P2, allocator_type>&& __source) {
826    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
827        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
828    __table_.__node_handle_merge_unique(__source.__table_);
829  }
830  template <class _H2, class _P2>
831  _LIBCPP_HIDE_FROM_ABI void merge(unordered_multiset<key_type, _H2, _P2, allocator_type>& __source) {
832    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
833        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
834    __table_.__node_handle_merge_unique(__source.__table_);
835  }
836  template <class _H2, class _P2>
837  _LIBCPP_HIDE_FROM_ABI void merge(unordered_multiset<key_type, _H2, _P2, allocator_type>&& __source) {
838    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
839        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
840    __table_.__node_handle_merge_unique(__source.__table_);
841  }
842#  endif
843
844  _LIBCPP_HIDE_FROM_ABI void swap(unordered_set& __u) _NOEXCEPT_(__is_nothrow_swappable_v<__table>) {
845    __table_.swap(__u.__table_);
846  }
847
848  _LIBCPP_HIDE_FROM_ABI hasher hash_function() const { return __table_.hash_function(); }
849  _LIBCPP_HIDE_FROM_ABI key_equal key_eq() const { return __table_.key_eq(); }
850
851  _LIBCPP_HIDE_FROM_ABI iterator find(const key_type& __k) { return __table_.find(__k); }
852  _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const { return __table_.find(__k); }
853#  if _LIBCPP_STD_VER >= 20
854  template <class _K2, enable_if_t<__is_transparent_v<hasher, _K2> && __is_transparent_v<key_equal, _K2>>* = nullptr>
855  _LIBCPP_HIDE_FROM_ABI iterator find(const _K2& __k) {
856    return __table_.find(__k);
857  }
858  template <class _K2, enable_if_t<__is_transparent_v<hasher, _K2> && __is_transparent_v<key_equal, _K2>>* = nullptr>
859  _LIBCPP_HIDE_FROM_ABI const_iterator find(const _K2& __k) const {
860    return __table_.find(__k);
861  }
862#  endif // _LIBCPP_STD_VER >= 20
863
864  _LIBCPP_HIDE_FROM_ABI size_type count(const key_type& __k) const { return __table_.__count_unique(__k); }
865#  if _LIBCPP_STD_VER >= 20
866  template <class _K2, enable_if_t<__is_transparent_v<hasher, _K2> && __is_transparent_v<key_equal, _K2>>* = nullptr>
867  _LIBCPP_HIDE_FROM_ABI size_type count(const _K2& __k) const {
868    return __table_.__count_unique(__k);
869  }
870#  endif // _LIBCPP_STD_VER >= 20
871
872#  if _LIBCPP_STD_VER >= 20
873  _LIBCPP_HIDE_FROM_ABI bool contains(const key_type& __k) const { return find(__k) != end(); }
874
875  template <class _K2, enable_if_t<__is_transparent_v<hasher, _K2> && __is_transparent_v<key_equal, _K2>>* = nullptr>
876  _LIBCPP_HIDE_FROM_ABI bool contains(const _K2& __k) const {
877    return find(__k) != end();
878  }
879#  endif // _LIBCPP_STD_VER >= 20
880
881  _LIBCPP_HIDE_FROM_ABI pair<iterator, iterator> equal_range(const key_type& __k) {
882    return __table_.__equal_range_unique(__k);
883  }
884  _LIBCPP_HIDE_FROM_ABI pair<const_iterator, const_iterator> equal_range(const key_type& __k) const {
885    return __table_.__equal_range_unique(__k);
886  }
887#  if _LIBCPP_STD_VER >= 20
888  template <class _K2, enable_if_t<__is_transparent_v<hasher, _K2> && __is_transparent_v<key_equal, _K2>>* = nullptr>
889  _LIBCPP_HIDE_FROM_ABI pair<iterator, iterator> equal_range(const _K2& __k) {
890    return __table_.__equal_range_unique(__k);
891  }
892  template <class _K2, enable_if_t<__is_transparent_v<hasher, _K2> && __is_transparent_v<key_equal, _K2>>* = nullptr>
893  _LIBCPP_HIDE_FROM_ABI pair<const_iterator, const_iterator> equal_range(const _K2& __k) const {
894    return __table_.__equal_range_unique(__k);
895  }
896#  endif // _LIBCPP_STD_VER >= 20
897
898  _LIBCPP_HIDE_FROM_ABI size_type bucket_count() const _NOEXCEPT { return __table_.bucket_count(); }
899  _LIBCPP_HIDE_FROM_ABI size_type max_bucket_count() const _NOEXCEPT { return __table_.max_bucket_count(); }
900
901  _LIBCPP_HIDE_FROM_ABI size_type bucket_size(size_type __n) const { return __table_.bucket_size(__n); }
902  _LIBCPP_HIDE_FROM_ABI size_type bucket(const key_type& __k) const { return __table_.bucket(__k); }
903
904  _LIBCPP_HIDE_FROM_ABI local_iterator begin(size_type __n) { return __table_.begin(__n); }
905  _LIBCPP_HIDE_FROM_ABI local_iterator end(size_type __n) { return __table_.end(__n); }
906  _LIBCPP_HIDE_FROM_ABI const_local_iterator begin(size_type __n) const { return __table_.cbegin(__n); }
907  _LIBCPP_HIDE_FROM_ABI const_local_iterator end(size_type __n) const { return __table_.cend(__n); }
908  _LIBCPP_HIDE_FROM_ABI const_local_iterator cbegin(size_type __n) const { return __table_.cbegin(__n); }
909  _LIBCPP_HIDE_FROM_ABI const_local_iterator cend(size_type __n) const { return __table_.cend(__n); }
910
911  _LIBCPP_HIDE_FROM_ABI float load_factor() const _NOEXCEPT { return __table_.load_factor(); }
912  _LIBCPP_HIDE_FROM_ABI float max_load_factor() const _NOEXCEPT { return __table_.max_load_factor(); }
913  _LIBCPP_HIDE_FROM_ABI void max_load_factor(float __mlf) { __table_.max_load_factor(__mlf); }
914  _LIBCPP_HIDE_FROM_ABI void rehash(size_type __n) { __table_.__rehash_unique(__n); }
915  _LIBCPP_HIDE_FROM_ABI void reserve(size_type __n) { __table_.__reserve_unique(__n); }
916};
917
918#  if _LIBCPP_STD_VER >= 17
919template <class _InputIterator,
920          class _Hash      = hash<__iter_value_type<_InputIterator>>,
921          class _Pred      = equal_to<__iter_value_type<_InputIterator>>,
922          class _Allocator = allocator<__iter_value_type<_InputIterator>>,
923          class            = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
924          class            = enable_if_t<!__is_allocator<_Hash>::value>,
925          class            = enable_if_t<!is_integral<_Hash>::value>,
926          class            = enable_if_t<!__is_allocator<_Pred>::value>,
927          class            = enable_if_t<__is_allocator<_Allocator>::value>>
928unordered_set(_InputIterator,
929              _InputIterator,
930              typename allocator_traits<_Allocator>::size_type = 0,
931              _Hash                                            = _Hash(),
932              _Pred                                            = _Pred(),
933              _Allocator = _Allocator()) -> unordered_set<__iter_value_type<_InputIterator>, _Hash, _Pred, _Allocator>;
934
935#    if _LIBCPP_STD_VER >= 23
936template <ranges::input_range _Range,
937          class _Hash      = hash<ranges::range_value_t<_Range>>,
938          class _Pred      = equal_to<ranges::range_value_t<_Range>>,
939          class _Allocator = allocator<ranges::range_value_t<_Range>>,
940          class            = enable_if_t<!__is_allocator<_Hash>::value>,
941          class            = enable_if_t<!is_integral<_Hash>::value>,
942          class            = enable_if_t<!__is_allocator<_Pred>::value>,
943          class            = enable_if_t<__is_allocator<_Allocator>::value>>
944unordered_set(
945    from_range_t,
946    _Range&&,
947    typename allocator_traits<_Allocator>::size_type = 0,
948    _Hash                                            = _Hash(),
949    _Pred                                            = _Pred(),
950    _Allocator = _Allocator()) -> unordered_set<ranges::range_value_t<_Range>, _Hash, _Pred, _Allocator>; // C++23
951#    endif
952
953template <class _Tp,
954          class _Hash      = hash<_Tp>,
955          class _Pred      = equal_to<_Tp>,
956          class _Allocator = allocator<_Tp>,
957          class            = enable_if_t<!__is_allocator<_Hash>::value>,
958          class            = enable_if_t<!is_integral<_Hash>::value>,
959          class            = enable_if_t<!__is_allocator<_Pred>::value>,
960          class            = enable_if_t<__is_allocator<_Allocator>::value>>
961unordered_set(initializer_list<_Tp>,
962              typename allocator_traits<_Allocator>::size_type = 0,
963              _Hash                                            = _Hash(),
964              _Pred                                            = _Pred(),
965              _Allocator = _Allocator()) -> unordered_set<_Tp, _Hash, _Pred, _Allocator>;
966
967template <class _InputIterator,
968          class _Allocator,
969          class = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
970          class = enable_if_t<__is_allocator<_Allocator>::value>>
971unordered_set(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type, _Allocator)
972    -> unordered_set<__iter_value_type<_InputIterator>,
973                     hash<__iter_value_type<_InputIterator>>,
974                     equal_to<__iter_value_type<_InputIterator>>,
975                     _Allocator>;
976
977template <class _InputIterator,
978          class _Hash,
979          class _Allocator,
980          class = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
981          class = enable_if_t<!__is_allocator<_Hash>::value>,
982          class = enable_if_t<!is_integral<_Hash>::value>,
983          class = enable_if_t<__is_allocator<_Allocator>::value>>
984unordered_set(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
985    -> unordered_set<__iter_value_type<_InputIterator>, _Hash, equal_to<__iter_value_type<_InputIterator>>, _Allocator>;
986
987#    if _LIBCPP_STD_VER >= 23
988
989template <ranges::input_range _Range, class _Allocator, class = enable_if_t<__is_allocator<_Allocator>::value>>
990unordered_set(from_range_t, _Range&&, typename allocator_traits<_Allocator>::size_type, _Allocator)
991    -> unordered_set<ranges::range_value_t<_Range>,
992                     hash<ranges::range_value_t<_Range>>,
993                     equal_to<ranges::range_value_t<_Range>>,
994                     _Allocator>;
995
996template <ranges::input_range _Range, class _Allocator, class = enable_if_t<__is_allocator<_Allocator>::value>>
997unordered_set(from_range_t, _Range&&, _Allocator)
998    -> unordered_set<ranges::range_value_t<_Range>,
999                     hash<ranges::range_value_t<_Range>>,
1000                     equal_to<ranges::range_value_t<_Range>>,
1001                     _Allocator>;
1002
1003template <ranges::input_range _Range,
1004          class _Hash,
1005          class _Allocator,
1006          class = enable_if_t<!__is_allocator<_Hash>::value>,
1007          class = enable_if_t<!is_integral<_Hash>::value>,
1008          class = enable_if_t<__is_allocator<_Allocator>::value>>
1009unordered_set(from_range_t, _Range&&, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
1010    -> unordered_set<ranges::range_value_t<_Range>, _Hash, equal_to<ranges::range_value_t<_Range>>, _Allocator>;
1011
1012#    endif
1013
1014template <class _Tp, class _Allocator, class = enable_if_t<__is_allocator<_Allocator>::value>>
1015unordered_set(initializer_list<_Tp>, typename allocator_traits<_Allocator>::size_type, _Allocator)
1016    -> unordered_set<_Tp, hash<_Tp>, equal_to<_Tp>, _Allocator>;
1017
1018template <class _Tp,
1019          class _Hash,
1020          class _Allocator,
1021          class = enable_if_t<!__is_allocator<_Hash>::value>,
1022          class = enable_if_t<!is_integral<_Hash>::value>,
1023          class = enable_if_t<__is_allocator<_Allocator>::value>>
1024unordered_set(initializer_list<_Tp>, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
1025    -> unordered_set<_Tp, _Hash, equal_to<_Tp>, _Allocator>;
1026#  endif
1027
1028template <class _Value, class _Hash, class _Pred, class _Alloc>
1029unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(size_type __n, const hasher& __hf, const key_equal& __eql)
1030    : __table_(__hf, __eql) {
1031  __table_.__rehash_unique(__n);
1032}
1033
1034template <class _Value, class _Hash, class _Pred, class _Alloc>
1035unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1036    size_type __n, const hasher& __hf, const key_equal& __eql, const allocator_type& __a)
1037    : __table_(__hf, __eql, __a) {
1038  __table_.__rehash_unique(__n);
1039}
1040
1041template <class _Value, class _Hash, class _Pred, class _Alloc>
1042template <class _InputIterator>
1043unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(_InputIterator __first, _InputIterator __last) {
1044  insert(__first, __last);
1045}
1046
1047template <class _Value, class _Hash, class _Pred, class _Alloc>
1048template <class _InputIterator>
1049unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1050    _InputIterator __first, _InputIterator __last, size_type __n, const hasher& __hf, const key_equal& __eql)
1051    : __table_(__hf, __eql) {
1052  __table_.__rehash_unique(__n);
1053  insert(__first, __last);
1054}
1055
1056template <class _Value, class _Hash, class _Pred, class _Alloc>
1057template <class _InputIterator>
1058unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1059    _InputIterator __first,
1060    _InputIterator __last,
1061    size_type __n,
1062    const hasher& __hf,
1063    const key_equal& __eql,
1064    const allocator_type& __a)
1065    : __table_(__hf, __eql, __a) {
1066  __table_.__rehash_unique(__n);
1067  insert(__first, __last);
1068}
1069
1070template <class _Value, class _Hash, class _Pred, class _Alloc>
1071inline unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(const allocator_type& __a) : __table_(__a) {}
1072
1073template <class _Value, class _Hash, class _Pred, class _Alloc>
1074unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(const unordered_set& __u) : __table_(__u.__table_) {
1075  __table_.__rehash_unique(__u.bucket_count());
1076  insert(__u.begin(), __u.end());
1077}
1078
1079template <class _Value, class _Hash, class _Pred, class _Alloc>
1080unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(const unordered_set& __u, const allocator_type& __a)
1081    : __table_(__u.__table_, __a) {
1082  __table_.__rehash_unique(__u.bucket_count());
1083  insert(__u.begin(), __u.end());
1084}
1085
1086#  ifndef _LIBCPP_CXX03_LANG
1087
1088template <class _Value, class _Hash, class _Pred, class _Alloc>
1089inline unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(unordered_set&& __u)
1090    _NOEXCEPT_(is_nothrow_move_constructible<__table>::value)
1091    : __table_(std::move(__u.__table_)) {}
1092
1093template <class _Value, class _Hash, class _Pred, class _Alloc>
1094unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(unordered_set&& __u, const allocator_type& __a)
1095    : __table_(std::move(__u.__table_), __a) {
1096  if (__a != __u.get_allocator()) {
1097    iterator __i = __u.begin();
1098    while (__u.size() != 0)
1099      __table_.__insert_unique(std::move(__u.__table_.remove(__i++)->__get_value()));
1100  }
1101}
1102
1103template <class _Value, class _Hash, class _Pred, class _Alloc>
1104unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(initializer_list<value_type> __il) {
1105  insert(__il.begin(), __il.end());
1106}
1107
1108template <class _Value, class _Hash, class _Pred, class _Alloc>
1109unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1110    initializer_list<value_type> __il, size_type __n, const hasher& __hf, const key_equal& __eql)
1111    : __table_(__hf, __eql) {
1112  __table_.__rehash_unique(__n);
1113  insert(__il.begin(), __il.end());
1114}
1115
1116template <class _Value, class _Hash, class _Pred, class _Alloc>
1117unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(
1118    initializer_list<value_type> __il,
1119    size_type __n,
1120    const hasher& __hf,
1121    const key_equal& __eql,
1122    const allocator_type& __a)
1123    : __table_(__hf, __eql, __a) {
1124  __table_.__rehash_unique(__n);
1125  insert(__il.begin(), __il.end());
1126}
1127
1128template <class _Value, class _Hash, class _Pred, class _Alloc>
1129inline unordered_set<_Value, _Hash, _Pred, _Alloc>&
1130unordered_set<_Value, _Hash, _Pred, _Alloc>::operator=(unordered_set&& __u)
1131    _NOEXCEPT_(is_nothrow_move_assignable<__table>::value) {
1132  __table_ = std::move(__u.__table_);
1133  return *this;
1134}
1135
1136template <class _Value, class _Hash, class _Pred, class _Alloc>
1137inline unordered_set<_Value, _Hash, _Pred, _Alloc>&
1138unordered_set<_Value, _Hash, _Pred, _Alloc>::operator=(initializer_list<value_type> __il) {
1139  __table_.__assign_unique(__il.begin(), __il.end());
1140  return *this;
1141}
1142
1143#  endif // _LIBCPP_CXX03_LANG
1144
1145template <class _Value, class _Hash, class _Pred, class _Alloc>
1146template <class _InputIterator>
1147inline void unordered_set<_Value, _Hash, _Pred, _Alloc>::insert(_InputIterator __first, _InputIterator __last) {
1148  for (; __first != __last; ++__first)
1149    __table_.__insert_unique(*__first);
1150}
1151
1152template <class _Value, class _Hash, class _Pred, class _Alloc>
1153inline _LIBCPP_HIDE_FROM_ABI void
1154swap(unordered_set<_Value, _Hash, _Pred, _Alloc>& __x, unordered_set<_Value, _Hash, _Pred, _Alloc>& __y)
1155    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y))) {
1156  __x.swap(__y);
1157}
1158
1159#  if _LIBCPP_STD_VER >= 20
1160template <class _Value, class _Hash, class _Pred, class _Alloc, class _Predicate>
1161inline _LIBCPP_HIDE_FROM_ABI typename unordered_set<_Value, _Hash, _Pred, _Alloc>::size_type
1162erase_if(unordered_set<_Value, _Hash, _Pred, _Alloc>& __c, _Predicate __pred) {
1163  return std::__libcpp_erase_if_container(__c, __pred);
1164}
1165#  endif
1166
1167template <class _Value, class _Hash, class _Pred, class _Alloc>
1168_LIBCPP_HIDE_FROM_ABI bool operator==(const unordered_set<_Value, _Hash, _Pred, _Alloc>& __x,
1169                                      const unordered_set<_Value, _Hash, _Pred, _Alloc>& __y) {
1170  if (__x.size() != __y.size())
1171    return false;
1172  typedef typename unordered_set<_Value, _Hash, _Pred, _Alloc>::const_iterator const_iterator;
1173  for (const_iterator __i = __x.begin(), __ex = __x.end(), __ey = __y.end(); __i != __ex; ++__i) {
1174    const_iterator __j = __y.find(*__i);
1175    if (__j == __ey || !(*__i == *__j))
1176      return false;
1177  }
1178  return true;
1179}
1180
1181#  if _LIBCPP_STD_VER <= 17
1182
1183template <class _Value, class _Hash, class _Pred, class _Alloc>
1184inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const unordered_set<_Value, _Hash, _Pred, _Alloc>& __x,
1185                                             const unordered_set<_Value, _Hash, _Pred, _Alloc>& __y) {
1186  return !(__x == __y);
1187}
1188
1189#  endif
1190
1191template <class _Value, class _Hash, class _Pred, class _Alloc>
1192struct __container_traits<unordered_set<_Value, _Hash, _Pred, _Alloc> > {
1193  // http://eel.is/c++draft/unord.req.except#2
1194  //  For unordered associative containers, if an exception is thrown by any operation
1195  //  other than the container's hash function from within an insert or emplace function
1196  //  inserting a single element, the insertion has no effect.
1197  static _LIBCPP_CONSTEXPR const bool __emplacement_has_strong_exception_safety_guarantee =
1198      __is_nothrow_invocable_v<_Hash, const _Value&>;
1199};
1200
1201template <class _Value, class _Hash = hash<_Value>, class _Pred = equal_to<_Value>, class _Alloc = allocator<_Value> >
1202class _LIBCPP_TEMPLATE_VIS unordered_multiset {
1203public:
1204  // types
1205  typedef _Value key_type;
1206  typedef key_type value_type;
1207  typedef __type_identity_t<_Hash> hasher;
1208  typedef __type_identity_t<_Pred> key_equal;
1209  typedef __type_identity_t<_Alloc> allocator_type;
1210  typedef value_type& reference;
1211  typedef const value_type& const_reference;
1212  static_assert(is_same<value_type, typename allocator_type::value_type>::value,
1213                "Allocator::value_type must be same type as value_type");
1214
1215private:
1216  typedef __hash_table<value_type, hasher, key_equal, allocator_type> __table;
1217
1218  __table __table_;
1219
1220public:
1221  typedef typename __table::pointer pointer;
1222  typedef typename __table::const_pointer const_pointer;
1223  typedef typename __table::size_type size_type;
1224  typedef typename __table::difference_type difference_type;
1225
1226  typedef typename __table::const_iterator iterator;
1227  typedef typename __table::const_iterator const_iterator;
1228  typedef typename __table::const_local_iterator local_iterator;
1229  typedef typename __table::const_local_iterator const_local_iterator;
1230
1231#  if _LIBCPP_STD_VER >= 17
1232  typedef __set_node_handle<typename __table::__node, allocator_type> node_type;
1233#  endif
1234
1235  template <class _Value2, class _Hash2, class _Pred2, class _Alloc2>
1236  friend class _LIBCPP_TEMPLATE_VIS unordered_set;
1237  template <class _Value2, class _Hash2, class _Pred2, class _Alloc2>
1238  friend class _LIBCPP_TEMPLATE_VIS unordered_multiset;
1239
1240  _LIBCPP_HIDE_FROM_ABI unordered_multiset() _NOEXCEPT_(is_nothrow_default_constructible<__table>::value) {}
1241  explicit _LIBCPP_HIDE_FROM_ABI
1242  unordered_multiset(size_type __n, const hasher& __hf = hasher(), const key_equal& __eql = key_equal());
1243  _LIBCPP_HIDE_FROM_ABI
1244  unordered_multiset(size_type __n, const hasher& __hf, const key_equal& __eql, const allocator_type& __a);
1245#  if _LIBCPP_STD_VER >= 14
1246  inline _LIBCPP_HIDE_FROM_ABI unordered_multiset(size_type __n, const allocator_type& __a)
1247      : unordered_multiset(__n, hasher(), key_equal(), __a) {}
1248  inline _LIBCPP_HIDE_FROM_ABI unordered_multiset(size_type __n, const hasher& __hf, const allocator_type& __a)
1249      : unordered_multiset(__n, __hf, key_equal(), __a) {}
1250#  endif
1251  template <class _InputIterator>
1252  _LIBCPP_HIDE_FROM_ABI unordered_multiset(_InputIterator __first, _InputIterator __last);
1253  template <class _InputIterator>
1254  _LIBCPP_HIDE_FROM_ABI unordered_multiset(
1255      _InputIterator __first,
1256      _InputIterator __last,
1257      size_type __n,
1258      const hasher& __hf     = hasher(),
1259      const key_equal& __eql = key_equal());
1260  template <class _InputIterator>
1261  _LIBCPP_HIDE_FROM_ABI unordered_multiset(
1262      _InputIterator __first,
1263      _InputIterator __last,
1264      size_type __n,
1265      const hasher& __hf,
1266      const key_equal& __eql,
1267      const allocator_type& __a);
1268
1269#  if _LIBCPP_STD_VER >= 23
1270  template <_ContainerCompatibleRange<value_type> _Range>
1271  _LIBCPP_HIDE_FROM_ABI unordered_multiset(
1272      from_range_t,
1273      _Range&& __range,
1274      size_type __n             = /*implementation-defined*/ 0,
1275      const hasher& __hf        = hasher(),
1276      const key_equal& __eql    = key_equal(),
1277      const allocator_type& __a = allocator_type())
1278      : __table_(__hf, __eql, __a) {
1279    if (__n > 0) {
1280      __table_.__rehash_multi(__n);
1281    }
1282    insert_range(std::forward<_Range>(__range));
1283  }
1284#  endif
1285
1286#  if _LIBCPP_STD_VER >= 14
1287  template <class _InputIterator>
1288  inline _LIBCPP_HIDE_FROM_ABI
1289  unordered_multiset(_InputIterator __first, _InputIterator __last, size_type __n, const allocator_type& __a)
1290      : unordered_multiset(__first, __last, __n, hasher(), key_equal(), __a) {}
1291  template <class _InputIterator>
1292  inline _LIBCPP_HIDE_FROM_ABI unordered_multiset(
1293      _InputIterator __first, _InputIterator __last, size_type __n, const hasher& __hf, const allocator_type& __a)
1294      : unordered_multiset(__first, __last, __n, __hf, key_equal(), __a) {}
1295#  endif
1296
1297#  if _LIBCPP_STD_VER >= 23
1298  template <_ContainerCompatibleRange<value_type> _Range>
1299  _LIBCPP_HIDE_FROM_ABI unordered_multiset(from_range_t, _Range&& __range, size_type __n, const allocator_type& __a)
1300      : unordered_multiset(from_range, std::forward<_Range>(__range), __n, hasher(), key_equal(), __a) {}
1301
1302  template <_ContainerCompatibleRange<value_type> _Range>
1303  _LIBCPP_HIDE_FROM_ABI
1304  unordered_multiset(from_range_t, _Range&& __range, size_type __n, const hasher& __hf, const allocator_type& __a)
1305      : unordered_multiset(from_range, std::forward<_Range>(__range), __n, __hf, key_equal(), __a) {}
1306#  endif
1307
1308  _LIBCPP_HIDE_FROM_ABI explicit unordered_multiset(const allocator_type& __a);
1309  _LIBCPP_HIDE_FROM_ABI unordered_multiset(const unordered_multiset& __u);
1310  _LIBCPP_HIDE_FROM_ABI unordered_multiset(const unordered_multiset& __u, const allocator_type& __a);
1311#  ifndef _LIBCPP_CXX03_LANG
1312  _LIBCPP_HIDE_FROM_ABI unordered_multiset(unordered_multiset&& __u)
1313      _NOEXCEPT_(is_nothrow_move_constructible<__table>::value);
1314  _LIBCPP_HIDE_FROM_ABI unordered_multiset(unordered_multiset&& __u, const allocator_type& __a);
1315  _LIBCPP_HIDE_FROM_ABI unordered_multiset(initializer_list<value_type> __il);
1316  _LIBCPP_HIDE_FROM_ABI unordered_multiset(
1317      initializer_list<value_type> __il,
1318      size_type __n,
1319      const hasher& __hf     = hasher(),
1320      const key_equal& __eql = key_equal());
1321  _LIBCPP_HIDE_FROM_ABI unordered_multiset(
1322      initializer_list<value_type> __il,
1323      size_type __n,
1324      const hasher& __hf,
1325      const key_equal& __eql,
1326      const allocator_type& __a);
1327#    if _LIBCPP_STD_VER >= 14
1328  inline _LIBCPP_HIDE_FROM_ABI
1329  unordered_multiset(initializer_list<value_type> __il, size_type __n, const allocator_type& __a)
1330      : unordered_multiset(__il, __n, hasher(), key_equal(), __a) {}
1331  inline _LIBCPP_HIDE_FROM_ABI
1332  unordered_multiset(initializer_list<value_type> __il, size_type __n, const hasher& __hf, const allocator_type& __a)
1333      : unordered_multiset(__il, __n, __hf, key_equal(), __a) {}
1334#    endif
1335#  endif // _LIBCPP_CXX03_LANG
1336  _LIBCPP_HIDE_FROM_ABI ~unordered_multiset() {
1337    static_assert(sizeof(std::__diagnose_unordered_container_requirements<_Value, _Hash, _Pred>(0)), "");
1338  }
1339
1340  _LIBCPP_HIDE_FROM_ABI unordered_multiset& operator=(const unordered_multiset& __u) {
1341    __table_ = __u.__table_;
1342    return *this;
1343  }
1344#  ifndef _LIBCPP_CXX03_LANG
1345  _LIBCPP_HIDE_FROM_ABI unordered_multiset& operator=(unordered_multiset&& __u)
1346      _NOEXCEPT_(is_nothrow_move_assignable<__table>::value);
1347  _LIBCPP_HIDE_FROM_ABI unordered_multiset& operator=(initializer_list<value_type> __il);
1348#  endif // _LIBCPP_CXX03_LANG
1349
1350  _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT {
1351    return allocator_type(__table_.__node_alloc());
1352  }
1353
1354  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool empty() const _NOEXCEPT { return __table_.size() == 0; }
1355  _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return __table_.size(); }
1356  _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT { return __table_.max_size(); }
1357
1358  _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return __table_.begin(); }
1359  _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT { return __table_.end(); }
1360  _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return __table_.begin(); }
1361  _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return __table_.end(); }
1362  _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT { return __table_.begin(); }
1363  _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT { return __table_.end(); }
1364
1365#  ifndef _LIBCPP_CXX03_LANG
1366  template <class... _Args>
1367  _LIBCPP_HIDE_FROM_ABI iterator emplace(_Args&&... __args) {
1368    return __table_.__emplace_multi(std::forward<_Args>(__args)...);
1369  }
1370  template <class... _Args>
1371  _LIBCPP_HIDE_FROM_ABI iterator emplace_hint(const_iterator __p, _Args&&... __args) {
1372    return __table_.__emplace_hint_multi(__p, std::forward<_Args>(__args)...);
1373  }
1374
1375  _LIBCPP_HIDE_FROM_ABI iterator insert(value_type&& __x) { return __table_.__insert_multi(std::move(__x)); }
1376  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, value_type&& __x) {
1377    return __table_.__insert_multi(__p, std::move(__x));
1378  }
1379  _LIBCPP_HIDE_FROM_ABI void insert(initializer_list<value_type> __il) { insert(__il.begin(), __il.end()); }
1380#  endif // _LIBCPP_CXX03_LANG
1381
1382  _LIBCPP_HIDE_FROM_ABI iterator insert(const value_type& __x) { return __table_.__insert_multi(__x); }
1383
1384  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, const value_type& __x) {
1385    return __table_.__insert_multi(__p, __x);
1386  }
1387
1388  template <class _InputIterator>
1389  _LIBCPP_HIDE_FROM_ABI void insert(_InputIterator __first, _InputIterator __last);
1390
1391#  if _LIBCPP_STD_VER >= 23
1392  template <_ContainerCompatibleRange<value_type> _Range>
1393  _LIBCPP_HIDE_FROM_ABI void insert_range(_Range&& __range) {
1394    for (auto&& __element : __range) {
1395      __table_.__insert_multi(std::forward<decltype(__element)>(__element));
1396    }
1397  }
1398#  endif
1399
1400#  if _LIBCPP_STD_VER >= 17
1401  _LIBCPP_HIDE_FROM_ABI iterator insert(node_type&& __nh) {
1402    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__nh.empty() || __nh.get_allocator() == get_allocator(),
1403                                        "node_type with incompatible allocator passed to unordered_multiset::insert()");
1404    return __table_.template __node_handle_insert_multi<node_type>(std::move(__nh));
1405  }
1406  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __hint, node_type&& __nh) {
1407    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(__nh.empty() || __nh.get_allocator() == get_allocator(),
1408                                        "node_type with incompatible allocator passed to unordered_multiset::insert()");
1409    return __table_.template __node_handle_insert_multi<node_type>(__hint, std::move(__nh));
1410  }
1411  _LIBCPP_HIDE_FROM_ABI node_type extract(const_iterator __position) {
1412    return __table_.template __node_handle_extract<node_type>(__position);
1413  }
1414  _LIBCPP_HIDE_FROM_ABI node_type extract(key_type const& __key) {
1415    return __table_.template __node_handle_extract<node_type>(__key);
1416  }
1417
1418  template <class _H2, class _P2>
1419  _LIBCPP_HIDE_FROM_ABI void merge(unordered_multiset<key_type, _H2, _P2, allocator_type>& __source) {
1420    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
1421        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
1422    return __table_.__node_handle_merge_multi(__source.__table_);
1423  }
1424  template <class _H2, class _P2>
1425  _LIBCPP_HIDE_FROM_ABI void merge(unordered_multiset<key_type, _H2, _P2, allocator_type>&& __source) {
1426    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
1427        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
1428    return __table_.__node_handle_merge_multi(__source.__table_);
1429  }
1430  template <class _H2, class _P2>
1431  _LIBCPP_HIDE_FROM_ABI void merge(unordered_set<key_type, _H2, _P2, allocator_type>& __source) {
1432    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
1433        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
1434    return __table_.__node_handle_merge_multi(__source.__table_);
1435  }
1436  template <class _H2, class _P2>
1437  _LIBCPP_HIDE_FROM_ABI void merge(unordered_set<key_type, _H2, _P2, allocator_type>&& __source) {
1438    _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
1439        __source.get_allocator() == get_allocator(), "merging container with incompatible allocator");
1440    return __table_.__node_handle_merge_multi(__source.__table_);
1441  }
1442#  endif
1443
1444  _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __p) { return __table_.erase(__p); }
1445  _LIBCPP_HIDE_FROM_ABI size_type erase(const key_type& __k) { return __table_.__erase_multi(__k); }
1446  _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __first, const_iterator __last) {
1447    return __table_.erase(__first, __last);
1448  }
1449  _LIBCPP_HIDE_FROM_ABI void clear() _NOEXCEPT { __table_.clear(); }
1450
1451  _LIBCPP_HIDE_FROM_ABI void swap(unordered_multiset& __u) _NOEXCEPT_(__is_nothrow_swappable_v<__table>) {
1452    __table_.swap(__u.__table_);
1453  }
1454
1455  _LIBCPP_HIDE_FROM_ABI hasher hash_function() const { return __table_.hash_function(); }
1456  _LIBCPP_HIDE_FROM_ABI key_equal key_eq() const { return __table_.key_eq(); }
1457
1458  _LIBCPP_HIDE_FROM_ABI iterator find(const key_type& __k) { return __table_.find(__k); }
1459  _LIBCPP_HIDE_FROM_ABI const_iterator find(const key_type& __k) const { return __table_.find(__k); }
1460#  if _LIBCPP_STD_VER >= 20
1461  template <class _K2, enable_if_t<__is_transparent_v<hasher, _K2> && __is_transparent_v<key_equal, _K2>>* = nullptr>
1462  _LIBCPP_HIDE_FROM_ABI iterator find(const _K2& __k) {
1463    return __table_.find(__k);
1464  }
1465  template <class _K2, enable_if_t<__is_transparent_v<hasher, _K2> && __is_transparent_v<key_equal, _K2>>* = nullptr>
1466  _LIBCPP_HIDE_FROM_ABI const_iterator find(const _K2& __k) const {
1467    return __table_.find(__k);
1468  }
1469#  endif // _LIBCPP_STD_VER >= 20
1470
1471  _LIBCPP_HIDE_FROM_ABI size_type count(const key_type& __k) const { return __table_.__count_multi(__k); }
1472#  if _LIBCPP_STD_VER >= 20
1473  template <class _K2, enable_if_t<__is_transparent_v<hasher, _K2> && __is_transparent_v<key_equal, _K2>>* = nullptr>
1474  _LIBCPP_HIDE_FROM_ABI size_type count(const _K2& __k) const {
1475    return __table_.__count_multi(__k);
1476  }
1477#  endif // _LIBCPP_STD_VER >= 20
1478
1479#  if _LIBCPP_STD_VER >= 20
1480  _LIBCPP_HIDE_FROM_ABI bool contains(const key_type& __k) const { return find(__k) != end(); }
1481
1482  template <class _K2, enable_if_t<__is_transparent_v<hasher, _K2> && __is_transparent_v<key_equal, _K2>>* = nullptr>
1483  _LIBCPP_HIDE_FROM_ABI bool contains(const _K2& __k) const {
1484    return find(__k) != end();
1485  }
1486#  endif // _LIBCPP_STD_VER >= 20
1487
1488  _LIBCPP_HIDE_FROM_ABI pair<iterator, iterator> equal_range(const key_type& __k) {
1489    return __table_.__equal_range_multi(__k);
1490  }
1491  _LIBCPP_HIDE_FROM_ABI pair<const_iterator, const_iterator> equal_range(const key_type& __k) const {
1492    return __table_.__equal_range_multi(__k);
1493  }
1494#  if _LIBCPP_STD_VER >= 20
1495  template <class _K2, enable_if_t<__is_transparent_v<hasher, _K2> && __is_transparent_v<key_equal, _K2>>* = nullptr>
1496  _LIBCPP_HIDE_FROM_ABI pair<iterator, iterator> equal_range(const _K2& __k) {
1497    return __table_.__equal_range_multi(__k);
1498  }
1499  template <class _K2, enable_if_t<__is_transparent_v<hasher, _K2> && __is_transparent_v<key_equal, _K2>>* = nullptr>
1500  _LIBCPP_HIDE_FROM_ABI pair<const_iterator, const_iterator> equal_range(const _K2& __k) const {
1501    return __table_.__equal_range_multi(__k);
1502  }
1503#  endif // _LIBCPP_STD_VER >= 20
1504
1505  _LIBCPP_HIDE_FROM_ABI size_type bucket_count() const _NOEXCEPT { return __table_.bucket_count(); }
1506  _LIBCPP_HIDE_FROM_ABI size_type max_bucket_count() const _NOEXCEPT { return __table_.max_bucket_count(); }
1507
1508  _LIBCPP_HIDE_FROM_ABI size_type bucket_size(size_type __n) const { return __table_.bucket_size(__n); }
1509  _LIBCPP_HIDE_FROM_ABI size_type bucket(const key_type& __k) const { return __table_.bucket(__k); }
1510
1511  _LIBCPP_HIDE_FROM_ABI local_iterator begin(size_type __n) { return __table_.begin(__n); }
1512  _LIBCPP_HIDE_FROM_ABI local_iterator end(size_type __n) { return __table_.end(__n); }
1513  _LIBCPP_HIDE_FROM_ABI const_local_iterator begin(size_type __n) const { return __table_.cbegin(__n); }
1514  _LIBCPP_HIDE_FROM_ABI const_local_iterator end(size_type __n) const { return __table_.cend(__n); }
1515  _LIBCPP_HIDE_FROM_ABI const_local_iterator cbegin(size_type __n) const { return __table_.cbegin(__n); }
1516  _LIBCPP_HIDE_FROM_ABI const_local_iterator cend(size_type __n) const { return __table_.cend(__n); }
1517
1518  _LIBCPP_HIDE_FROM_ABI float load_factor() const _NOEXCEPT { return __table_.load_factor(); }
1519  _LIBCPP_HIDE_FROM_ABI float max_load_factor() const _NOEXCEPT { return __table_.max_load_factor(); }
1520  _LIBCPP_HIDE_FROM_ABI void max_load_factor(float __mlf) { __table_.max_load_factor(__mlf); }
1521  _LIBCPP_HIDE_FROM_ABI void rehash(size_type __n) { __table_.__rehash_multi(__n); }
1522  _LIBCPP_HIDE_FROM_ABI void reserve(size_type __n) { __table_.__reserve_multi(__n); }
1523};
1524
1525#  if _LIBCPP_STD_VER >= 17
1526template <class _InputIterator,
1527          class _Hash      = hash<__iter_value_type<_InputIterator>>,
1528          class _Pred      = equal_to<__iter_value_type<_InputIterator>>,
1529          class _Allocator = allocator<__iter_value_type<_InputIterator>>,
1530          class            = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
1531          class            = enable_if_t<!__is_allocator<_Hash>::value>,
1532          class            = enable_if_t<!is_integral<_Hash>::value>,
1533          class            = enable_if_t<!__is_allocator<_Pred>::value>,
1534          class            = enable_if_t<__is_allocator<_Allocator>::value>>
1535unordered_multiset(
1536    _InputIterator,
1537    _InputIterator,
1538    typename allocator_traits<_Allocator>::size_type = 0,
1539    _Hash                                            = _Hash(),
1540    _Pred                                            = _Pred(),
1541    _Allocator = _Allocator()) -> unordered_multiset<__iter_value_type<_InputIterator>, _Hash, _Pred, _Allocator>;
1542
1543#    if _LIBCPP_STD_VER >= 23
1544template <ranges::input_range _Range,
1545          class _Hash      = hash<ranges::range_value_t<_Range>>,
1546          class _Pred      = equal_to<ranges::range_value_t<_Range>>,
1547          class _Allocator = allocator<ranges::range_value_t<_Range>>,
1548          class            = enable_if_t<!__is_allocator<_Hash>::value>,
1549          class            = enable_if_t<!is_integral<_Hash>::value>,
1550          class            = enable_if_t<!__is_allocator<_Pred>::value>,
1551          class            = enable_if_t<__is_allocator<_Allocator>::value>>
1552unordered_multiset(
1553    from_range_t,
1554    _Range&&,
1555    typename allocator_traits<_Allocator>::size_type = 0,
1556    _Hash                                            = _Hash(),
1557    _Pred                                            = _Pred(),
1558    _Allocator = _Allocator()) -> unordered_multiset<ranges::range_value_t<_Range>, _Hash, _Pred, _Allocator>; // C++23
1559#    endif
1560
1561template <class _Tp,
1562          class _Hash      = hash<_Tp>,
1563          class _Pred      = equal_to<_Tp>,
1564          class _Allocator = allocator<_Tp>,
1565          class            = enable_if_t<!__is_allocator<_Hash>::value>,
1566          class            = enable_if_t<!is_integral<_Hash>::value>,
1567          class            = enable_if_t<!__is_allocator<_Pred>::value>,
1568          class            = enable_if_t<__is_allocator<_Allocator>::value>>
1569unordered_multiset(initializer_list<_Tp>,
1570                   typename allocator_traits<_Allocator>::size_type = 0,
1571                   _Hash                                            = _Hash(),
1572                   _Pred                                            = _Pred(),
1573                   _Allocator = _Allocator()) -> unordered_multiset<_Tp, _Hash, _Pred, _Allocator>;
1574
1575template <class _InputIterator,
1576          class _Allocator,
1577          class = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
1578          class = enable_if_t<__is_allocator<_Allocator>::value>>
1579unordered_multiset(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type, _Allocator)
1580    -> unordered_multiset<__iter_value_type<_InputIterator>,
1581                          hash<__iter_value_type<_InputIterator>>,
1582                          equal_to<__iter_value_type<_InputIterator>>,
1583                          _Allocator>;
1584
1585template <class _InputIterator,
1586          class _Hash,
1587          class _Allocator,
1588          class = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
1589          class = enable_if_t<!__is_allocator<_Hash>::value>,
1590          class = enable_if_t<!is_integral<_Hash>::value>,
1591          class = enable_if_t<__is_allocator<_Allocator>::value>>
1592unordered_multiset(_InputIterator, _InputIterator, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
1593    -> unordered_multiset<__iter_value_type<_InputIterator>,
1594                          _Hash,
1595                          equal_to<__iter_value_type<_InputIterator>>,
1596                          _Allocator>;
1597
1598#    if _LIBCPP_STD_VER >= 23
1599
1600template <ranges::input_range _Range, class _Allocator, class = enable_if_t<__is_allocator<_Allocator>::value>>
1601unordered_multiset(from_range_t, _Range&&, typename allocator_traits<_Allocator>::size_type, _Allocator)
1602    -> unordered_multiset<ranges::range_value_t<_Range>,
1603                          hash<ranges::range_value_t<_Range>>,
1604                          equal_to<ranges::range_value_t<_Range>>,
1605                          _Allocator>;
1606
1607template <ranges::input_range _Range, class _Allocator, class = enable_if_t<__is_allocator<_Allocator>::value>>
1608unordered_multiset(from_range_t, _Range&&, _Allocator)
1609    -> unordered_multiset<ranges::range_value_t<_Range>,
1610                          hash<ranges::range_value_t<_Range>>,
1611                          equal_to<ranges::range_value_t<_Range>>,
1612                          _Allocator>;
1613
1614template <ranges::input_range _Range,
1615          class _Hash,
1616          class _Allocator,
1617          class = enable_if_t<!__is_allocator<_Hash>::value>,
1618          class = enable_if_t<!is_integral<_Hash>::value>,
1619          class = enable_if_t<__is_allocator<_Allocator>::value>>
1620unordered_multiset(from_range_t, _Range&&, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
1621    -> unordered_multiset<ranges::range_value_t<_Range>, _Hash, equal_to<ranges::range_value_t<_Range>>, _Allocator>;
1622
1623#    endif
1624
1625template <class _Tp, class _Allocator, class = enable_if_t<__is_allocator<_Allocator>::value>>
1626unordered_multiset(initializer_list<_Tp>, typename allocator_traits<_Allocator>::size_type, _Allocator)
1627    -> unordered_multiset<_Tp, hash<_Tp>, equal_to<_Tp>, _Allocator>;
1628
1629template <class _Tp,
1630          class _Hash,
1631          class _Allocator,
1632          class = enable_if_t<!__is_allocator<_Hash>::value>,
1633          class = enable_if_t<!is_integral<_Hash>::value>,
1634          class = enable_if_t<__is_allocator<_Allocator>::value>>
1635unordered_multiset(initializer_list<_Tp>, typename allocator_traits<_Allocator>::size_type, _Hash, _Allocator)
1636    -> unordered_multiset<_Tp, _Hash, equal_to<_Tp>, _Allocator>;
1637#  endif
1638
1639template <class _Value, class _Hash, class _Pred, class _Alloc>
1640unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1641    size_type __n, const hasher& __hf, const key_equal& __eql)
1642    : __table_(__hf, __eql) {
1643  __table_.__rehash_multi(__n);
1644}
1645
1646template <class _Value, class _Hash, class _Pred, class _Alloc>
1647unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1648    size_type __n, const hasher& __hf, const key_equal& __eql, const allocator_type& __a)
1649    : __table_(__hf, __eql, __a) {
1650  __table_.__rehash_multi(__n);
1651}
1652
1653template <class _Value, class _Hash, class _Pred, class _Alloc>
1654template <class _InputIterator>
1655unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(_InputIterator __first, _InputIterator __last) {
1656  insert(__first, __last);
1657}
1658
1659template <class _Value, class _Hash, class _Pred, class _Alloc>
1660template <class _InputIterator>
1661unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1662    _InputIterator __first, _InputIterator __last, size_type __n, const hasher& __hf, const key_equal& __eql)
1663    : __table_(__hf, __eql) {
1664  __table_.__rehash_multi(__n);
1665  insert(__first, __last);
1666}
1667
1668template <class _Value, class _Hash, class _Pred, class _Alloc>
1669template <class _InputIterator>
1670unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1671    _InputIterator __first,
1672    _InputIterator __last,
1673    size_type __n,
1674    const hasher& __hf,
1675    const key_equal& __eql,
1676    const allocator_type& __a)
1677    : __table_(__hf, __eql, __a) {
1678  __table_.__rehash_multi(__n);
1679  insert(__first, __last);
1680}
1681
1682template <class _Value, class _Hash, class _Pred, class _Alloc>
1683inline unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(const allocator_type& __a)
1684    : __table_(__a) {}
1685
1686template <class _Value, class _Hash, class _Pred, class _Alloc>
1687unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(const unordered_multiset& __u)
1688    : __table_(__u.__table_) {
1689  __table_.__rehash_multi(__u.bucket_count());
1690  insert(__u.begin(), __u.end());
1691}
1692
1693template <class _Value, class _Hash, class _Pred, class _Alloc>
1694unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1695    const unordered_multiset& __u, const allocator_type& __a)
1696    : __table_(__u.__table_, __a) {
1697  __table_.__rehash_multi(__u.bucket_count());
1698  insert(__u.begin(), __u.end());
1699}
1700
1701#  ifndef _LIBCPP_CXX03_LANG
1702
1703template <class _Value, class _Hash, class _Pred, class _Alloc>
1704inline unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(unordered_multiset&& __u)
1705    _NOEXCEPT_(is_nothrow_move_constructible<__table>::value)
1706    : __table_(std::move(__u.__table_)) {}
1707
1708template <class _Value, class _Hash, class _Pred, class _Alloc>
1709unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1710    unordered_multiset&& __u, const allocator_type& __a)
1711    : __table_(std::move(__u.__table_), __a) {
1712  if (__a != __u.get_allocator()) {
1713    iterator __i = __u.begin();
1714    while (__u.size() != 0)
1715      __table_.__insert_multi(std::move(__u.__table_.remove(__i++)->__get_value()));
1716  }
1717}
1718
1719template <class _Value, class _Hash, class _Pred, class _Alloc>
1720unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(initializer_list<value_type> __il) {
1721  insert(__il.begin(), __il.end());
1722}
1723
1724template <class _Value, class _Hash, class _Pred, class _Alloc>
1725unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1726    initializer_list<value_type> __il, size_type __n, const hasher& __hf, const key_equal& __eql)
1727    : __table_(__hf, __eql) {
1728  __table_.__rehash_multi(__n);
1729  insert(__il.begin(), __il.end());
1730}
1731
1732template <class _Value, class _Hash, class _Pred, class _Alloc>
1733unordered_multiset<_Value, _Hash, _Pred, _Alloc>::unordered_multiset(
1734    initializer_list<value_type> __il,
1735    size_type __n,
1736    const hasher& __hf,
1737    const key_equal& __eql,
1738    const allocator_type& __a)
1739    : __table_(__hf, __eql, __a) {
1740  __table_.__rehash_multi(__n);
1741  insert(__il.begin(), __il.end());
1742}
1743
1744template <class _Value, class _Hash, class _Pred, class _Alloc>
1745inline unordered_multiset<_Value, _Hash, _Pred, _Alloc>&
1746unordered_multiset<_Value, _Hash, _Pred, _Alloc>::operator=(unordered_multiset&& __u)
1747    _NOEXCEPT_(is_nothrow_move_assignable<__table>::value) {
1748  __table_ = std::move(__u.__table_);
1749  return *this;
1750}
1751
1752template <class _Value, class _Hash, class _Pred, class _Alloc>
1753inline unordered_multiset<_Value, _Hash, _Pred, _Alloc>&
1754unordered_multiset<_Value, _Hash, _Pred, _Alloc>::operator=(initializer_list<value_type> __il) {
1755  __table_.__assign_multi(__il.begin(), __il.end());
1756  return *this;
1757}
1758
1759#  endif // _LIBCPP_CXX03_LANG
1760
1761template <class _Value, class _Hash, class _Pred, class _Alloc>
1762template <class _InputIterator>
1763inline void unordered_multiset<_Value, _Hash, _Pred, _Alloc>::insert(_InputIterator __first, _InputIterator __last) {
1764  for (; __first != __last; ++__first)
1765    __table_.__insert_multi(*__first);
1766}
1767
1768template <class _Value, class _Hash, class _Pred, class _Alloc>
1769inline _LIBCPP_HIDE_FROM_ABI void
1770swap(unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __x, unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __y)
1771    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y))) {
1772  __x.swap(__y);
1773}
1774
1775#  if _LIBCPP_STD_VER >= 20
1776template <class _Value, class _Hash, class _Pred, class _Alloc, class _Predicate>
1777inline _LIBCPP_HIDE_FROM_ABI typename unordered_multiset<_Value, _Hash, _Pred, _Alloc>::size_type
1778erase_if(unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __c, _Predicate __pred) {
1779  return std::__libcpp_erase_if_container(__c, __pred);
1780}
1781#  endif
1782
1783template <class _Value, class _Hash, class _Pred, class _Alloc>
1784_LIBCPP_HIDE_FROM_ABI bool operator==(const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __x,
1785                                      const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __y) {
1786  if (__x.size() != __y.size())
1787    return false;
1788  typedef typename unordered_multiset<_Value, _Hash, _Pred, _Alloc>::const_iterator const_iterator;
1789  typedef pair<const_iterator, const_iterator> _EqRng;
1790  for (const_iterator __i = __x.begin(), __ex = __x.end(); __i != __ex;) {
1791    _EqRng __xeq = __x.equal_range(*__i);
1792    _EqRng __yeq = __y.equal_range(*__i);
1793    if (std::distance(__xeq.first, __xeq.second) != std::distance(__yeq.first, __yeq.second) ||
1794        !std::is_permutation(__xeq.first, __xeq.second, __yeq.first))
1795      return false;
1796    __i = __xeq.second;
1797  }
1798  return true;
1799}
1800
1801#  if _LIBCPP_STD_VER <= 17
1802
1803template <class _Value, class _Hash, class _Pred, class _Alloc>
1804inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __x,
1805                                             const unordered_multiset<_Value, _Hash, _Pred, _Alloc>& __y) {
1806  return !(__x == __y);
1807}
1808
1809#  endif
1810
1811template <class _Value, class _Hash, class _Pred, class _Alloc>
1812struct __container_traits<unordered_multiset<_Value, _Hash, _Pred, _Alloc> > {
1813  // http://eel.is/c++draft/unord.req.except#2
1814  //  For unordered associative containers, if an exception is thrown by any operation
1815  //  other than the container's hash function from within an insert or emplace function
1816  //  inserting a single element, the insertion has no effect.
1817  static _LIBCPP_CONSTEXPR const bool __emplacement_has_strong_exception_safety_guarantee =
1818      __is_nothrow_invocable_v<_Hash, const _Value&>;
1819};
1820
1821_LIBCPP_END_NAMESPACE_STD
1822
1823#  if _LIBCPP_STD_VER >= 17
1824_LIBCPP_BEGIN_NAMESPACE_STD
1825namespace pmr {
1826template <class _KeyT, class _HashT = std::hash<_KeyT>, class _PredT = std::equal_to<_KeyT>>
1827using unordered_set _LIBCPP_AVAILABILITY_PMR = std::unordered_set<_KeyT, _HashT, _PredT, polymorphic_allocator<_KeyT>>;
1828
1829template <class _KeyT, class _HashT = std::hash<_KeyT>, class _PredT = std::equal_to<_KeyT>>
1830using unordered_multiset _LIBCPP_AVAILABILITY_PMR =
1831    std::unordered_multiset<_KeyT, _HashT, _PredT, polymorphic_allocator<_KeyT>>;
1832} // namespace pmr
1833_LIBCPP_END_NAMESPACE_STD
1834#  endif
1835
1836_LIBCPP_POP_MACROS
1837
1838#  if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
1839#    include <cmath>
1840#    include <concepts>
1841#    include <cstdlib>
1842#    include <functional>
1843#    include <iterator>
1844#    include <stdexcept>
1845#    include <type_traits>
1846#  endif
1847#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
1848
1849#endif // _LIBCPP_UNORDERED_SET
1850