1 // Multiset implementation -*- C++ -*-
2
3 // Copyright (C) 2001-2023 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24
25 /*
26 *
27 * Copyright (c) 1994
28 * Hewlett-Packard Company
29 *
30 * Permission to use, copy, modify, distribute and sell this software
31 * and its documentation for any purpose is hereby granted without fee,
32 * provided that the above copyright notice appear in all copies and
33 * that both that copyright notice and this permission notice appear
34 * in supporting documentation. Hewlett-Packard Company makes no
35 * representations about the suitability of this software for any
36 * purpose. It is provided "as is" without express or implied warranty.
37 *
38 *
39 * Copyright (c) 1996
40 * Silicon Graphics Computer Systems, Inc.
41 *
42 * Permission to use, copy, modify, distribute and sell this software
43 * and its documentation for any purpose is hereby granted without fee,
44 * provided that the above copyright notice appear in all copies and
45 * that both that copyright notice and this permission notice appear
46 * in supporting documentation. Silicon Graphics makes no
47 * representations about the suitability of this software for any
48 * purpose. It is provided "as is" without express or implied warranty.
49 */
50
51 /** @file bits/stl_multiset.h
52 * This is an internal header file, included by other library headers.
53 * Do not attempt to use it directly. @headername{set}
54 */
55
56 #ifndef _STL_MULTISET_H
57 #define _STL_MULTISET_H 1
58
59 #include <bits/concept_check.h>
60 #if __cplusplus >= 201103L
61 #include <initializer_list>
62 #endif
63
64 namespace std _GLIBCXX_VISIBILITY(default)
65 {
66 _GLIBCXX_BEGIN_NAMESPACE_VERSION
67 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
68
69 template<typename _Key, typename _Compare, typename _Alloc>
70 class set;
71
72 /**
73 * @brief A standard container made up of elements, which can be retrieved
74 * in logarithmic time.
75 *
76 * @ingroup associative_containers
77 * @headerfile set
78 * @since C++98
79 *
80 * @tparam _Key Type of key objects.
81 * @tparam _Compare Comparison function object type, defaults to less<_Key>.
82 * @tparam _Alloc Allocator type, defaults to allocator<_Key>.
83 *
84 * Meets the requirements of a <a href="tables.html#65">container</a>, a
85 * <a href="tables.html#66">reversible container</a>, and an
86 * <a href="tables.html#69">associative container</a> (using equivalent
87 * keys). For a @c multiset<Key> the key_type and value_type are Key.
88 *
89 * Multisets support bidirectional iterators.
90 *
91 * The private tree data is declared exactly the same way for set and
92 * multiset; the distinction is made entirely in how the tree functions are
93 * called (*_unique versus *_equal, same as the standard).
94 */
95 template <typename _Key, typename _Compare = std::less<_Key>,
96 typename _Alloc = std::allocator<_Key> >
97 class multiset
98 {
99 #ifdef _GLIBCXX_CONCEPT_CHECKS
100 // concept requirements
101 typedef typename _Alloc::value_type _Alloc_value_type;
102 # if __cplusplus < 201103L
103 __glibcxx_class_requires(_Key, _SGIAssignableConcept)
104 # endif
105 __glibcxx_class_requires4(_Compare, bool, _Key, _Key,
106 _BinaryFunctionConcept)
107 __glibcxx_class_requires2(_Key, _Alloc_value_type, _SameTypeConcept)
108 #endif
109
110 #if __cplusplus >= 201103L
111 static_assert(is_same<typename remove_cv<_Key>::type, _Key>::value,
112 "std::multiset must have a non-const, non-volatile value_type");
113 # if __cplusplus > 201703L || defined __STRICT_ANSI__
114 static_assert(is_same<typename _Alloc::value_type, _Key>::value,
115 "std::multiset must have the same value_type as its allocator");
116 # endif
117 #endif
118
119 public:
120 // typedefs:
121 typedef _Key key_type;
122 typedef _Key value_type;
123 typedef _Compare key_compare;
124 typedef _Compare value_compare;
125 typedef _Alloc allocator_type;
126
127 private:
128 /// This turns a red-black tree into a [multi]set.
129 typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
130 rebind<_Key>::other _Key_alloc_type;
131
132 typedef _Rb_tree<key_type, value_type, _Identity<value_type>,
133 key_compare, _Key_alloc_type> _Rep_type;
134 /// The actual tree structure.
135 _Rep_type _M_t;
136
137 typedef __gnu_cxx::__alloc_traits<_Key_alloc_type> _Alloc_traits;
138
139 public:
140 typedef typename _Alloc_traits::pointer pointer;
141 typedef typename _Alloc_traits::const_pointer const_pointer;
142 typedef typename _Alloc_traits::reference reference;
143 typedef typename _Alloc_traits::const_reference const_reference;
144 // _GLIBCXX_RESOLVE_LIB_DEFECTS
145 // DR 103. set::iterator is required to be modifiable,
146 // but this allows modification of keys.
147 typedef typename _Rep_type::const_iterator iterator;
148 typedef typename _Rep_type::const_iterator const_iterator;
149 typedef typename _Rep_type::const_reverse_iterator reverse_iterator;
150 typedef typename _Rep_type::const_reverse_iterator const_reverse_iterator;
151 typedef typename _Rep_type::size_type size_type;
152 typedef typename _Rep_type::difference_type difference_type;
153
154 #if __cplusplus > 201402L
155 using node_type = typename _Rep_type::node_type;
156 #endif
157
158 // allocation/deallocation
159 /**
160 * @brief Default constructor creates no elements.
161 */
162 #if __cplusplus < 201103L
163 multiset() : _M_t() { }
164 #else
165 multiset() = default;
166 #endif
167
168 /**
169 * @brief Creates a %multiset with no elements.
170 * @param __comp Comparator to use.
171 * @param __a An allocator object.
172 */
173 explicit
174 multiset(const _Compare& __comp,
175 const allocator_type& __a = allocator_type())
176 : _M_t(__comp, _Key_alloc_type(__a)) { }
177
178 /**
179 * @brief Builds a %multiset from a range.
180 * @param __first An input iterator.
181 * @param __last An input iterator.
182 *
183 * Create a %multiset consisting of copies of the elements from
184 * [first,last). This is linear in N if the range is already sorted,
185 * and NlogN otherwise (where N is distance(__first,__last)).
186 */
187 template<typename _InputIterator>
188 multiset(_InputIterator __first, _InputIterator __last)
189 : _M_t()
190 { _M_t._M_insert_range_equal(__first, __last); }
191
192 /**
193 * @brief Builds a %multiset from a range.
194 * @param __first An input iterator.
195 * @param __last An input iterator.
196 * @param __comp A comparison functor.
197 * @param __a An allocator object.
198 *
199 * Create a %multiset consisting of copies of the elements from
200 * [__first,__last). This is linear in N if the range is already sorted,
201 * and NlogN otherwise (where N is distance(__first,__last)).
202 */
203 template<typename _InputIterator>
204 multiset(_InputIterator __first, _InputIterator __last,
205 const _Compare& __comp,
206 const allocator_type& __a = allocator_type())
207 : _M_t(__comp, _Key_alloc_type(__a))
208 { _M_t._M_insert_range_equal(__first, __last); }
209
210 /**
211 * @brief %Multiset copy constructor.
212 *
213 * Whether the allocator is copied depends on the allocator traits.
214 */
215 #if __cplusplus < 201103L
216 multiset(const multiset& __x)
217 : _M_t(__x._M_t) { }
218 #else
219 multiset(const multiset&) = default;
220
221 /**
222 * @brief %Multiset move constructor.
223 *
224 * The newly-created %multiset contains the exact contents of the
225 * moved instance. The moved instance is a valid, but unspecified
226 * %multiset.
227 */
228 multiset(multiset&&) = default;
229
230 /**
231 * @brief Builds a %multiset from an initializer_list.
232 * @param __l An initializer_list.
233 * @param __comp A comparison functor.
234 * @param __a An allocator object.
235 *
236 * Create a %multiset consisting of copies of the elements from
237 * the list. This is linear in N if the list is already sorted,
238 * and NlogN otherwise (where N is @a __l.size()).
239 */
240 multiset(initializer_list<value_type> __l,
241 const _Compare& __comp = _Compare(),
242 const allocator_type& __a = allocator_type())
243 : _M_t(__comp, _Key_alloc_type(__a))
244 { _M_t._M_insert_range_equal(__l.begin(), __l.end()); }
245
246 /// Allocator-extended default constructor.
247 explicit
248 multiset(const allocator_type& __a)
249 : _M_t(_Key_alloc_type(__a)) { }
250
251 /// Allocator-extended copy constructor.
252 multiset(const multiset& __m,
253 const __type_identity_t<allocator_type>& __a)
254 : _M_t(__m._M_t, _Key_alloc_type(__a)) { }
255
256 /// Allocator-extended move constructor.
257 multiset(multiset&& __m, const __type_identity_t<allocator_type>& __a)
258 noexcept(is_nothrow_copy_constructible<_Compare>::value
259 && _Alloc_traits::_S_always_equal())
260 : _M_t(std::move(__m._M_t), _Key_alloc_type(__a)) { }
261
262 /// Allocator-extended initialier-list constructor.
263 multiset(initializer_list<value_type> __l, const allocator_type& __a)
264 : _M_t(_Key_alloc_type(__a))
265 { _M_t._M_insert_range_equal(__l.begin(), __l.end()); }
266
267 /// Allocator-extended range constructor.
268 template<typename _InputIterator>
269 multiset(_InputIterator __first, _InputIterator __last,
270 const allocator_type& __a)
271 : _M_t(_Key_alloc_type(__a))
272 { _M_t._M_insert_range_equal(__first, __last); }
273
274 /**
275 * The dtor only erases the elements, and note that if the elements
276 * themselves are pointers, the pointed-to memory is not touched in any
277 * way. Managing the pointer is the user's responsibility.
278 */
279 ~multiset() = default;
280 #endif
281
282 /**
283 * @brief %Multiset assignment operator.
284 *
285 * Whether the allocator is copied depends on the allocator traits.
286 */
287 #if __cplusplus < 201103L
288 multiset&
289 operator=(const multiset& __x)
290 {
291 _M_t = __x._M_t;
292 return *this;
293 }
294 #else
295 multiset&
296 operator=(const multiset&) = default;
297
298 /// Move assignment operator.
299 multiset&
300 operator=(multiset&&) = default;
301
302 /**
303 * @brief %Multiset list assignment operator.
304 * @param __l An initializer_list.
305 *
306 * This function fills a %multiset with copies of the elements in the
307 * initializer list @a __l.
308 *
309 * Note that the assignment completely changes the %multiset and
310 * that the resulting %multiset's size is the same as the number
311 * of elements assigned.
312 */
313 multiset&
314 operator=(initializer_list<value_type> __l)
315 {
316 _M_t._M_assign_equal(__l.begin(), __l.end());
317 return *this;
318 }
319 #endif
320
321 // accessors:
322
323 /// Returns the comparison object.
324 key_compare
325 key_comp() const
326 { return _M_t.key_comp(); }
327 /// Returns the comparison object.
328 value_compare
329 value_comp() const
330 { return _M_t.key_comp(); }
331 /// Returns the memory allocation object.
332 allocator_type
333 get_allocator() const _GLIBCXX_NOEXCEPT
334 { return allocator_type(_M_t.get_allocator()); }
335
336 /**
337 * Returns a read-only (constant) iterator that points to the first
338 * element in the %multiset. Iteration is done in ascending order
339 * according to the keys.
340 */
341 iterator
342 begin() const _GLIBCXX_NOEXCEPT
343 { return _M_t.begin(); }
344
345 /**
346 * Returns a read-only (constant) iterator that points one past the last
347 * element in the %multiset. Iteration is done in ascending order
348 * according to the keys.
349 */
350 iterator
351 end() const _GLIBCXX_NOEXCEPT
352 { return _M_t.end(); }
353
354 /**
355 * Returns a read-only (constant) reverse iterator that points to the
356 * last element in the %multiset. Iteration is done in descending order
357 * according to the keys.
358 */
359 reverse_iterator
360 rbegin() const _GLIBCXX_NOEXCEPT
361 { return _M_t.rbegin(); }
362
363 /**
364 * Returns a read-only (constant) reverse iterator that points to the
365 * last element in the %multiset. Iteration is done in descending order
366 * according to the keys.
367 */
368 reverse_iterator
369 rend() const _GLIBCXX_NOEXCEPT
370 { return _M_t.rend(); }
371
372 #if __cplusplus >= 201103L
373 /**
374 * Returns a read-only (constant) iterator that points to the first
375 * element in the %multiset. Iteration is done in ascending order
376 * according to the keys.
377 */
378 iterator
379 cbegin() const noexcept
380 { return _M_t.begin(); }
381
382 /**
383 * Returns a read-only (constant) iterator that points one past the last
384 * element in the %multiset. Iteration is done in ascending order
385 * according to the keys.
386 */
387 iterator
388 cend() const noexcept
389 { return _M_t.end(); }
390
391 /**
392 * Returns a read-only (constant) reverse iterator that points to the
393 * last element in the %multiset. Iteration is done in descending order
394 * according to the keys.
395 */
396 reverse_iterator
397 crbegin() const noexcept
398 { return _M_t.rbegin(); }
399
400 /**
401 * Returns a read-only (constant) reverse iterator that points to the
402 * last element in the %multiset. Iteration is done in descending order
403 * according to the keys.
404 */
405 reverse_iterator
406 crend() const noexcept
407 { return _M_t.rend(); }
408 #endif
409
410 /// Returns true if the %set is empty.
411 _GLIBCXX_NODISCARD bool
412 empty() const _GLIBCXX_NOEXCEPT
413 { return _M_t.empty(); }
414
415 /// Returns the size of the %set.
416 size_type
417 size() const _GLIBCXX_NOEXCEPT
418 { return _M_t.size(); }
419
420 /// Returns the maximum size of the %set.
421 size_type
422 max_size() const _GLIBCXX_NOEXCEPT
423 { return _M_t.max_size(); }
424
425 /**
426 * @brief Swaps data with another %multiset.
427 * @param __x A %multiset of the same element and allocator types.
428 *
429 * This exchanges the elements between two multisets in constant time.
430 * (It is only swapping a pointer, an integer, and an instance of the @c
431 * Compare type (which itself is often stateless and empty), so it should
432 * be quite fast.)
433 * Note that the global std::swap() function is specialized such that
434 * std::swap(s1,s2) will feed to this function.
435 *
436 * Whether the allocators are swapped depends on the allocator traits.
437 */
438 void
439 swap(multiset& __x)
440 _GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Compare>::value)
441 { _M_t.swap(__x._M_t); }
442
443 // insert/erase
444 #if __cplusplus >= 201103L
445 /**
446 * @brief Builds and inserts an element into the %multiset.
447 * @param __args Arguments used to generate the element instance to be
448 * inserted.
449 * @return An iterator that points to the inserted element.
450 *
451 * This function inserts an element into the %multiset. Contrary
452 * to a std::set the %multiset does not rely on unique keys and thus
453 * multiple copies of the same element can be inserted.
454 *
455 * Insertion requires logarithmic time.
456 */
457 template<typename... _Args>
458 iterator
459 emplace(_Args&&... __args)
460 { return _M_t._M_emplace_equal(std::forward<_Args>(__args)...); }
461
462 /**
463 * @brief Builds and inserts an element into the %multiset.
464 * @param __pos An iterator that serves as a hint as to where the
465 * element should be inserted.
466 * @param __args Arguments used to generate the element instance to be
467 * inserted.
468 * @return An iterator that points to the inserted element.
469 *
470 * This function inserts an element into the %multiset. Contrary
471 * to a std::set the %multiset does not rely on unique keys and thus
472 * multiple copies of the same element can be inserted.
473 *
474 * Note that the first parameter is only a hint and can potentially
475 * improve the performance of the insertion process. A bad hint would
476 * cause no gains in efficiency.
477 *
478 * See https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
479 * for more on @a hinting.
480 *
481 * Insertion requires logarithmic time (if the hint is not taken).
482 */
483 template<typename... _Args>
484 iterator
485 emplace_hint(const_iterator __pos, _Args&&... __args)
486 {
487 return _M_t._M_emplace_hint_equal(__pos,
488 std::forward<_Args>(__args)...);
489 }
490 #endif
491
492 /**
493 * @brief Inserts an element into the %multiset.
494 * @param __x Element to be inserted.
495 * @return An iterator that points to the inserted element.
496 *
497 * This function inserts an element into the %multiset. Contrary
498 * to a std::set the %multiset does not rely on unique keys and thus
499 * multiple copies of the same element can be inserted.
500 *
501 * Insertion requires logarithmic time.
502 */
503 iterator
504 insert(const value_type& __x)
505 { return _M_t._M_insert_equal(__x); }
506
507 #if __cplusplus >= 201103L
508 iterator
509 insert(value_type&& __x)
510 { return _M_t._M_insert_equal(std::move(__x)); }
511 #endif
512
513 /**
514 * @brief Inserts an element into the %multiset.
515 * @param __position An iterator that serves as a hint as to where the
516 * element should be inserted.
517 * @param __x Element to be inserted.
518 * @return An iterator that points to the inserted element.
519 *
520 * This function inserts an element into the %multiset. Contrary
521 * to a std::set the %multiset does not rely on unique keys and thus
522 * multiple copies of the same element can be inserted.
523 *
524 * Note that the first parameter is only a hint and can potentially
525 * improve the performance of the insertion process. A bad hint would
526 * cause no gains in efficiency.
527 *
528 * See https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
529 * for more on @a hinting.
530 *
531 * Insertion requires logarithmic time (if the hint is not taken).
532 */
533 iterator
534 insert(const_iterator __position, const value_type& __x)
535 { return _M_t._M_insert_equal_(__position, __x); }
536
537 #if __cplusplus >= 201103L
538 iterator
539 insert(const_iterator __position, value_type&& __x)
540 { return _M_t._M_insert_equal_(__position, std::move(__x)); }
541 #endif
542
543 /**
544 * @brief A template function that tries to insert a range of elements.
545 * @param __first Iterator pointing to the start of the range to be
546 * inserted.
547 * @param __last Iterator pointing to the end of the range.
548 *
549 * Complexity similar to that of the range constructor.
550 */
551 template<typename _InputIterator>
552 void
553 insert(_InputIterator __first, _InputIterator __last)
554 { _M_t._M_insert_range_equal(__first, __last); }
555
556 #if __cplusplus >= 201103L
557 /**
558 * @brief Attempts to insert a list of elements into the %multiset.
559 * @param __l A std::initializer_list<value_type> of elements
560 * to be inserted.
561 *
562 * Complexity similar to that of the range constructor.
563 */
564 void
565 insert(initializer_list<value_type> __l)
566 { this->insert(__l.begin(), __l.end()); }
567 #endif
568
569 #if __cplusplus > 201402L
570 /// Extract a node.
571 node_type
572 extract(const_iterator __pos)
573 {
574 __glibcxx_assert(__pos != end());
575 return _M_t.extract(__pos);
576 }
577
578 /// Extract a node.
579 node_type
580 extract(const key_type& __x)
581 { return _M_t.extract(__x); }
582
583 /// Re-insert an extracted node.
584 iterator
585 insert(node_type&& __nh)
586 { return _M_t._M_reinsert_node_equal(std::move(__nh)); }
587
588 /// Re-insert an extracted node.
589 iterator
590 insert(const_iterator __hint, node_type&& __nh)
591 { return _M_t._M_reinsert_node_hint_equal(__hint, std::move(__nh)); }
592
593 template<typename, typename>
594 friend struct std::_Rb_tree_merge_helper;
595
596 template<typename _Compare1>
597 void
598 merge(multiset<_Key, _Compare1, _Alloc>& __source)
599 {
600 using _Merge_helper = _Rb_tree_merge_helper<multiset, _Compare1>;
601 _M_t._M_merge_equal(_Merge_helper::_S_get_tree(__source));
602 }
603
604 template<typename _Compare1>
605 void
606 merge(multiset<_Key, _Compare1, _Alloc>&& __source)
607 { merge(__source); }
608
609 template<typename _Compare1>
610 void
611 merge(set<_Key, _Compare1, _Alloc>& __source)
612 {
613 using _Merge_helper = _Rb_tree_merge_helper<multiset, _Compare1>;
614 _M_t._M_merge_equal(_Merge_helper::_S_get_tree(__source));
615 }
616
617 template<typename _Compare1>
618 void
619 merge(set<_Key, _Compare1, _Alloc>&& __source)
620 { merge(__source); }
621 #endif // C++17
622
623 #if __cplusplus >= 201103L
624 // _GLIBCXX_RESOLVE_LIB_DEFECTS
625 // DR 130. Associative erase should return an iterator.
626 /**
627 * @brief Erases an element from a %multiset.
628 * @param __position An iterator pointing to the element to be erased.
629 * @return An iterator pointing to the element immediately following
630 * @a position prior to the element being erased. If no such
631 * element exists, end() is returned.
632 *
633 * This function erases an element, pointed to by the given iterator,
634 * from a %multiset. Note that this function only erases the element,
635 * and that if the element is itself a pointer, the pointed-to memory is
636 * not touched in any way. Managing the pointer is the user's
637 * responsibility.
638 */
639 _GLIBCXX_ABI_TAG_CXX11
640 iterator
641 erase(const_iterator __position)
642 { return _M_t.erase(__position); }
643 #else
644 /**
645 * @brief Erases an element from a %multiset.
646 * @param __position An iterator pointing to the element to be erased.
647 *
648 * This function erases an element, pointed to by the given iterator,
649 * from a %multiset. Note that this function only erases the element,
650 * and that if the element is itself a pointer, the pointed-to memory is
651 * not touched in any way. Managing the pointer is the user's
652 * responsibility.
653 */
654 void
655 erase(iterator __position)
656 { _M_t.erase(__position); }
657 #endif
658
659 /**
660 * @brief Erases elements according to the provided key.
661 * @param __x Key of element to be erased.
662 * @return The number of elements erased.
663 *
664 * This function erases all elements located by the given key from a
665 * %multiset.
666 * Note that this function only erases the element, and that if
667 * the element is itself a pointer, the pointed-to memory is not touched
668 * in any way. Managing the pointer is the user's responsibility.
669 */
670 size_type
671 erase(const key_type& __x)
672 { return _M_t.erase(__x); }
673
674 #if __cplusplus >= 201103L
675 // _GLIBCXX_RESOLVE_LIB_DEFECTS
676 // DR 130. Associative erase should return an iterator.
677 /**
678 * @brief Erases a [first,last) range of elements from a %multiset.
679 * @param __first Iterator pointing to the start of the range to be
680 * erased.
681 * @param __last Iterator pointing to the end of the range to
682 * be erased.
683 * @return The iterator @a last.
684 *
685 * This function erases a sequence of elements from a %multiset.
686 * Note that this function only erases the elements, and that if
687 * the elements themselves are pointers, the pointed-to memory is not
688 * touched in any way. Managing the pointer is the user's
689 * responsibility.
690 */
691 _GLIBCXX_ABI_TAG_CXX11
692 iterator
693 erase(const_iterator __first, const_iterator __last)
694 { return _M_t.erase(__first, __last); }
695 #else
696 /**
697 * @brief Erases a [first,last) range of elements from a %multiset.
698 * @param first Iterator pointing to the start of the range to be
699 * erased.
700 * @param last Iterator pointing to the end of the range to be erased.
701 *
702 * This function erases a sequence of elements from a %multiset.
703 * Note that this function only erases the elements, and that if
704 * the elements themselves are pointers, the pointed-to memory is not
705 * touched in any way. Managing the pointer is the user's
706 * responsibility.
707 */
708 void
709 erase(iterator __first, iterator __last)
710 { _M_t.erase(__first, __last); }
711 #endif
712
713 /**
714 * Erases all elements in a %multiset. Note that this function only
715 * erases the elements, and that if the elements themselves are pointers,
716 * the pointed-to memory is not touched in any way. Managing the pointer
717 * is the user's responsibility.
718 */
719 void
720 clear() _GLIBCXX_NOEXCEPT
721 { _M_t.clear(); }
722
723 // multiset operations:
724
725 ///@{
726 /**
727 * @brief Finds the number of elements with given key.
728 * @param __x Key of elements to be located.
729 * @return Number of elements with specified key.
730 */
731 size_type
732 count(const key_type& __x) const
733 { return _M_t.count(__x); }
734
735 #if __cplusplus > 201103L
736 template<typename _Kt>
737 auto
738 count(const _Kt& __x) const -> decltype(_M_t._M_count_tr(__x))
739 { return _M_t._M_count_tr(__x); }
740 #endif
741 ///@}
742
743 #if __cplusplus > 201703L
744 ///@{
745 /**
746 * @brief Finds whether an element with the given key exists.
747 * @param __x Key of elements to be located.
748 * @return True if there is any element with the specified key.
749 */
750 bool
751 contains(const key_type& __x) const
752 { return _M_t.find(__x) != _M_t.end(); }
753
754 template<typename _Kt>
755 auto
756 contains(const _Kt& __x) const
757 -> decltype(_M_t._M_find_tr(__x), void(), true)
758 { return _M_t._M_find_tr(__x) != _M_t.end(); }
759 ///@}
760 #endif
761
762 // _GLIBCXX_RESOLVE_LIB_DEFECTS
763 // 214. set::find() missing const overload
764 ///@{
765 /**
766 * @brief Tries to locate an element in a %set.
767 * @param __x Element to be located.
768 * @return Iterator pointing to sought-after element, or end() if not
769 * found.
770 *
771 * This function takes a key and tries to locate the element with which
772 * the key matches. If successful the function returns an iterator
773 * pointing to the sought after element. If unsuccessful it returns the
774 * past-the-end ( @c end() ) iterator.
775 */
776 iterator
777 find(const key_type& __x)
778 { return _M_t.find(__x); }
779
780 const_iterator
781 find(const key_type& __x) const
782 { return _M_t.find(__x); }
783
784 #if __cplusplus > 201103L
785 template<typename _Kt>
786 auto
787 find(const _Kt& __x)
788 -> decltype(iterator{_M_t._M_find_tr(__x)})
789 { return iterator{_M_t._M_find_tr(__x)}; }
790
791 template<typename _Kt>
792 auto
793 find(const _Kt& __x) const
794 -> decltype(const_iterator{_M_t._M_find_tr(__x)})
795 { return const_iterator{_M_t._M_find_tr(__x)}; }
796 #endif
797 ///@}
798
799 ///@{
800 /**
801 * @brief Finds the beginning of a subsequence matching given key.
802 * @param __x Key to be located.
803 * @return Iterator pointing to first element equal to or greater
804 * than key, or end().
805 *
806 * This function returns the first element of a subsequence of elements
807 * that matches the given key. If unsuccessful it returns an iterator
808 * pointing to the first element that has a greater value than given key
809 * or end() if no such element exists.
810 */
811 iterator
812 lower_bound(const key_type& __x)
813 { return _M_t.lower_bound(__x); }
814
815 const_iterator
816 lower_bound(const key_type& __x) const
817 { return _M_t.lower_bound(__x); }
818
819 #if __cplusplus > 201103L
820 template<typename _Kt>
821 auto
822 lower_bound(const _Kt& __x)
823 -> decltype(iterator(_M_t._M_lower_bound_tr(__x)))
824 { return iterator(_M_t._M_lower_bound_tr(__x)); }
825
826 template<typename _Kt>
827 auto
828 lower_bound(const _Kt& __x) const
829 -> decltype(iterator(_M_t._M_lower_bound_tr(__x)))
830 { return iterator(_M_t._M_lower_bound_tr(__x)); }
831 #endif
832 ///@}
833
834 ///@{
835 /**
836 * @brief Finds the end of a subsequence matching given key.
837 * @param __x Key to be located.
838 * @return Iterator pointing to the first element
839 * greater than key, or end().
840 */
841 iterator
842 upper_bound(const key_type& __x)
843 { return _M_t.upper_bound(__x); }
844
845 const_iterator
846 upper_bound(const key_type& __x) const
847 { return _M_t.upper_bound(__x); }
848
849 #if __cplusplus > 201103L
850 template<typename _Kt>
851 auto
852 upper_bound(const _Kt& __x)
853 -> decltype(iterator(_M_t._M_upper_bound_tr(__x)))
854 { return iterator(_M_t._M_upper_bound_tr(__x)); }
855
856 template<typename _Kt>
857 auto
858 upper_bound(const _Kt& __x) const
859 -> decltype(iterator(_M_t._M_upper_bound_tr(__x)))
860 { return iterator(_M_t._M_upper_bound_tr(__x)); }
861 #endif
862 ///@}
863
864 ///@{
865 /**
866 * @brief Finds a subsequence matching given key.
867 * @param __x Key to be located.
868 * @return Pair of iterators that possibly points to the subsequence
869 * matching given key.
870 *
871 * This function is equivalent to
872 * @code
873 * std::make_pair(c.lower_bound(val),
874 * c.upper_bound(val))
875 * @endcode
876 * (but is faster than making the calls separately).
877 *
878 * This function probably only makes sense for multisets.
879 */
880 std::pair<iterator, iterator>
881 equal_range(const key_type& __x)
882 { return _M_t.equal_range(__x); }
883
884 std::pair<const_iterator, const_iterator>
885 equal_range(const key_type& __x) const
886 { return _M_t.equal_range(__x); }
887
888 #if __cplusplus > 201103L
889 template<typename _Kt>
890 auto
891 equal_range(const _Kt& __x)
892 -> decltype(pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)))
893 { return pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)); }
894
895 template<typename _Kt>
896 auto
897 equal_range(const _Kt& __x) const
898 -> decltype(pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)))
899 { return pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)); }
900 #endif
901 ///@}
902
903 template<typename _K1, typename _C1, typename _A1>
904 friend bool
905 operator==(const multiset<_K1, _C1, _A1>&,
906 const multiset<_K1, _C1, _A1>&);
907
908 #if __cpp_lib_three_way_comparison
909 template<typename _K1, typename _C1, typename _A1>
910 friend __detail::__synth3way_t<_K1>
911 operator<=>(const multiset<_K1, _C1, _A1>&,
912 const multiset<_K1, _C1, _A1>&);
913 #else
914 template<typename _K1, typename _C1, typename _A1>
915 friend bool
916 operator< (const multiset<_K1, _C1, _A1>&,
917 const multiset<_K1, _C1, _A1>&);
918 #endif
919 };
920
921 #if __cpp_deduction_guides >= 201606
922
923 template<typename _InputIterator,
924 typename _Compare =
925 less<typename iterator_traits<_InputIterator>::value_type>,
926 typename _Allocator =
927 allocator<typename iterator_traits<_InputIterator>::value_type>,
928 typename = _RequireInputIter<_InputIterator>,
929 typename = _RequireNotAllocator<_Compare>,
930 typename = _RequireAllocator<_Allocator>>
931 multiset(_InputIterator, _InputIterator,
932 _Compare = _Compare(), _Allocator = _Allocator())
933 -> multiset<typename iterator_traits<_InputIterator>::value_type,
934 _Compare, _Allocator>;
935
936 template<typename _Key,
937 typename _Compare = less<_Key>,
938 typename _Allocator = allocator<_Key>,
939 typename = _RequireNotAllocator<_Compare>,
940 typename = _RequireAllocator<_Allocator>>
941 multiset(initializer_list<_Key>,
942 _Compare = _Compare(), _Allocator = _Allocator())
943 -> multiset<_Key, _Compare, _Allocator>;
944
945 template<typename _InputIterator, typename _Allocator,
946 typename = _RequireInputIter<_InputIterator>,
947 typename = _RequireAllocator<_Allocator>>
948 multiset(_InputIterator, _InputIterator, _Allocator)
949 -> multiset<typename iterator_traits<_InputIterator>::value_type,
950 less<typename iterator_traits<_InputIterator>::value_type>,
951 _Allocator>;
952
953 template<typename _Key, typename _Allocator,
954 typename = _RequireAllocator<_Allocator>>
955 multiset(initializer_list<_Key>, _Allocator)
956 -> multiset<_Key, less<_Key>, _Allocator>;
957
958 #endif // deduction guides
959
960 /**
961 * @brief Multiset equality comparison.
962 * @param __x A %multiset.
963 * @param __y A %multiset of the same type as @a __x.
964 * @return True iff the size and elements of the multisets are equal.
965 *
966 * This is an equivalence relation. It is linear in the size of the
967 * multisets.
968 * Multisets are considered equivalent if their sizes are equal, and if
969 * corresponding elements compare equal.
970 */
971 template<typename _Key, typename _Compare, typename _Alloc>
972 inline bool
973 operator==(const multiset<_Key, _Compare, _Alloc>& __x,
974 const multiset<_Key, _Compare, _Alloc>& __y)
975 { return __x._M_t == __y._M_t; }
976
977 #if __cpp_lib_three_way_comparison
978 /**
979 * @brief Multiset ordering relation.
980 * @param __x A `multiset`.
981 * @param __y A `multiset` of the same type as `x`.
982 * @return A value indicating whether `__x` is less than, equal to,
983 * greater than, or incomparable with `__y`.
984 *
985 * This is a total ordering relation. It is linear in the size of the
986 * maps. The elements must be comparable with @c <.
987 *
988 * See `std::lexicographical_compare_three_way()` for how the determination
989 * is made. This operator is used to synthesize relational operators like
990 * `<` and `>=` etc.
991 */
992 template<typename _Key, typename _Compare, typename _Alloc>
993 inline __detail::__synth3way_t<_Key>
994 operator<=>(const multiset<_Key, _Compare, _Alloc>& __x,
995 const multiset<_Key, _Compare, _Alloc>& __y)
996 { return __x._M_t <=> __y._M_t; }
997 #else
998 /**
999 * @brief Multiset ordering relation.
1000 * @param __x A %multiset.
1001 * @param __y A %multiset of the same type as @a __x.
1002 * @return True iff @a __x is lexicographically less than @a __y.
1003 *
1004 * This is a total ordering relation. It is linear in the size of the
1005 * sets. The elements must be comparable with @c <.
1006 *
1007 * See std::lexicographical_compare() for how the determination is made.
1008 */
1009 template<typename _Key, typename _Compare, typename _Alloc>
1010 inline bool
1011 operator<(const multiset<_Key, _Compare, _Alloc>& __x,
1012 const multiset<_Key, _Compare, _Alloc>& __y)
1013 { return __x._M_t < __y._M_t; }
1014
1015 /// Returns !(x == y).
1016 template<typename _Key, typename _Compare, typename _Alloc>
1017 inline bool
1018 operator!=(const multiset<_Key, _Compare, _Alloc>& __x,
1019 const multiset<_Key, _Compare, _Alloc>& __y)
1020 { return !(__x == __y); }
1021
1022 /// Returns y < x.
1023 template<typename _Key, typename _Compare, typename _Alloc>
1024 inline bool
1025 operator>(const multiset<_Key,_Compare,_Alloc>& __x,
1026 const multiset<_Key,_Compare,_Alloc>& __y)
1027 { return __y < __x; }
1028
1029 /// Returns !(y < x)
1030 template<typename _Key, typename _Compare, typename _Alloc>
1031 inline bool
1032 operator<=(const multiset<_Key, _Compare, _Alloc>& __x,
1033 const multiset<_Key, _Compare, _Alloc>& __y)
1034 { return !(__y < __x); }
1035
1036 /// Returns !(x < y)
1037 template<typename _Key, typename _Compare, typename _Alloc>
1038 inline bool
1039 operator>=(const multiset<_Key, _Compare, _Alloc>& __x,
1040 const multiset<_Key, _Compare, _Alloc>& __y)
1041 { return !(__x < __y); }
1042 #endif // three-way comparison
1043
1044 /// See std::multiset::swap().
1045 template<typename _Key, typename _Compare, typename _Alloc>
1046 inline void
1047 swap(multiset<_Key, _Compare, _Alloc>& __x,
1048 multiset<_Key, _Compare, _Alloc>& __y)
1049 _GLIBCXX_NOEXCEPT_IF(noexcept(__x.swap(__y)))
1050 { __x.swap(__y); }
1051
1052 _GLIBCXX_END_NAMESPACE_CONTAINER
1053
1054 #if __cplusplus > 201402L
1055 // Allow std::multiset access to internals of compatible sets.
1056 template<typename _Val, typename _Cmp1, typename _Alloc, typename _Cmp2>
1057 struct
1058 _Rb_tree_merge_helper<_GLIBCXX_STD_C::multiset<_Val, _Cmp1, _Alloc>,
1059 _Cmp2>
1060 {
1061 private:
1062 friend class _GLIBCXX_STD_C::multiset<_Val, _Cmp1, _Alloc>;
1063
1064 static auto&
1065 _S_get_tree(_GLIBCXX_STD_C::set<_Val, _Cmp2, _Alloc>& __set)
1066 { return __set._M_t; }
1067
1068 static auto&
1069 _S_get_tree(_GLIBCXX_STD_C::multiset<_Val, _Cmp2, _Alloc>& __set)
1070 { return __set._M_t; }
1071 };
1072 #endif // C++17
1073
1074 _GLIBCXX_END_NAMESPACE_VERSION
1075 } // namespace std
1076
1077 #endif /* _STL_MULTISET_H */