1 // Multiset implementation -*- C++ -*-
2
3 // Copyright (C) 2001-2020 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
_GLIBCXX_VISIBILITY(default)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 *
78 *
79 * @tparam _Key Type of key objects.
80 * @tparam _Compare Comparison function object type, defaults to less<_Key>.
81 * @tparam _Alloc Allocator type, defaults to allocator<_Key>.
82 *
83 * Meets the requirements of a <a href="tables.html#65">container</a>, a
84 * <a href="tables.html#66">reversible container</a>, and an
85 * <a href="tables.html#69">associative container</a> (using equivalent
86 * keys). For a @c multiset<Key> the key_type and value_type are Key.
87 *
88 * Multisets support bidirectional iterators.
89 *
90 * The private tree data is declared exactly the same way for set and
91 * multiset; the distinction is made entirely in how the tree functions are
92 * called (*_unique versus *_equal, same as the standard).
93 */
94 template <typename _Key, typename _Compare = std::less<_Key>,
95 typename _Alloc = std::allocator<_Key> >
96 class multiset
97 {
98 #ifdef _GLIBCXX_CONCEPT_CHECKS
99 // concept requirements
100 typedef typename _Alloc::value_type _Alloc_value_type;
101 # if __cplusplus < 201103L
102 __glibcxx_class_requires(_Key, _SGIAssignableConcept)
103 # endif
104 __glibcxx_class_requires4(_Compare, bool, _Key, _Key,
105 _BinaryFunctionConcept)
106 __glibcxx_class_requires2(_Key, _Alloc_value_type, _SameTypeConcept)
107 #endif
108
109 #if __cplusplus >= 201103L
110 static_assert(is_same<typename remove_cv<_Key>::type, _Key>::value,
111 "std::multiset must have a non-const, non-volatile value_type");
112 # if __cplusplus > 201703L || defined __STRICT_ANSI__
113 static_assert(is_same<typename _Alloc::value_type, _Key>::value,
114 "std::multiset must have the same value_type as its allocator");
115 # endif
116 #endif
117
118 public:
119 // typedefs:
120 typedef _Key key_type;
121 typedef _Key value_type;
122 typedef _Compare key_compare;
123 typedef _Compare value_compare;
124 typedef _Alloc allocator_type;
125
126 private:
127 /// This turns a red-black tree into a [multi]set.
128 typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
129 rebind<_Key>::other _Key_alloc_type;
130
131 typedef _Rb_tree<key_type, value_type, _Identity<value_type>,
132 key_compare, _Key_alloc_type> _Rep_type;
133 /// The actual tree structure.
134 _Rep_type _M_t;
135
136 typedef __gnu_cxx::__alloc_traits<_Key_alloc_type> _Alloc_traits;
137
138 public:
139 typedef typename _Alloc_traits::pointer pointer;
140 typedef typename _Alloc_traits::const_pointer const_pointer;
141 typedef typename _Alloc_traits::reference reference;
142 typedef typename _Alloc_traits::const_reference const_reference;
143 // _GLIBCXX_RESOLVE_LIB_DEFECTS
144 // DR 103. set::iterator is required to be modifiable,
145 // but this allows modification of keys.
146 typedef typename _Rep_type::const_iterator iterator;
147 typedef typename _Rep_type::const_iterator const_iterator;
148 typedef typename _Rep_type::const_reverse_iterator reverse_iterator;
149 typedef typename _Rep_type::const_reverse_iterator const_reverse_iterator;
150 typedef typename _Rep_type::size_type size_type;
151 typedef typename _Rep_type::difference_type difference_type;
152
153 #if __cplusplus > 201402L
154 using node_type = typename _Rep_type::node_type;
155 #endif
156
157 // allocation/deallocation
158 /**
159 * @brief Default constructor creates no elements.
160 */
161 #if __cplusplus < 201103L
162 multiset() : _M_t() { }
163 #else
164 multiset() = default;
165 #endif
166
167 /**
168 * @brief Creates a %multiset with no elements.
169 * @param __comp Comparator to use.
170 * @param __a An allocator object.
171 */
172 explicit
173 multiset(const _Compare& __comp,
174 const allocator_type& __a = allocator_type())
175 : _M_t(__comp, _Key_alloc_type(__a)) { }
176
177 /**
178 * @brief Builds a %multiset from a range.
179 * @param __first An input iterator.
180 * @param __last An input iterator.
181 *
182 * Create a %multiset consisting of copies of the elements from
183 * [first,last). This is linear in N if the range is already sorted,
184 * and NlogN otherwise (where N is distance(__first,__last)).
185 */
186 template<typename _InputIterator>
187 multiset(_InputIterator __first, _InputIterator __last)
188 : _M_t()
189 { _M_t._M_insert_range_equal(__first, __last); }
190
191 /**
192 * @brief Builds a %multiset from a range.
193 * @param __first An input iterator.
194 * @param __last An input iterator.
195 * @param __comp A comparison functor.
196 * @param __a An allocator object.
197 *
198 * Create a %multiset consisting of copies of the elements from
199 * [__first,__last). This is linear in N if the range is already sorted,
200 * and NlogN otherwise (where N is distance(__first,__last)).
201 */
202 template<typename _InputIterator>
203 multiset(_InputIterator __first, _InputIterator __last,
204 const _Compare& __comp,
205 const allocator_type& __a = allocator_type())
206 : _M_t(__comp, _Key_alloc_type(__a))
207 { _M_t._M_insert_range_equal(__first, __last); }
208
209 /**
210 * @brief %Multiset copy constructor.
211 *
212 * Whether the allocator is copied depends on the allocator traits.
213 */
214 #if __cplusplus < 201103L
215 multiset(const multiset& __x)
216 : _M_t(__x._M_t) { }
217 #else
218 multiset(const multiset&) = default;
219
220 /**
221 * @brief %Multiset move constructor.
222 *
223 * The newly-created %multiset contains the exact contents of the
224 * moved instance. The moved instance is a valid, but unspecified
225 * %multiset.
226 */
227 multiset(multiset&&) = default;
228
229 /**
230 * @brief Builds a %multiset from an initializer_list.
231 * @param __l An initializer_list.
232 * @param __comp A comparison functor.
233 * @param __a An allocator object.
234 *
235 * Create a %multiset consisting of copies of the elements from
236 * the list. This is linear in N if the list is already sorted,
237 * and NlogN otherwise (where N is @a __l.size()).
238 */
239 multiset(initializer_list<value_type> __l,
240 const _Compare& __comp = _Compare(),
241 const allocator_type& __a = allocator_type())
242 : _M_t(__comp, _Key_alloc_type(__a))
243 { _M_t._M_insert_range_equal(__l.begin(), __l.end()); }
244
245 /// Allocator-extended default constructor.
246 explicit
247 multiset(const allocator_type& __a)
248 : _M_t(_Key_alloc_type(__a)) { }
249
250 /// Allocator-extended copy constructor.
251 multiset(const multiset& __m, const allocator_type& __a)
252 : _M_t(__m._M_t, _Key_alloc_type(__a)) { }
253
254 /// Allocator-extended move constructor.
255 multiset(multiset&& __m, const allocator_type& __a)
256 noexcept(is_nothrow_copy_constructible<_Compare>::value
257 && _Alloc_traits::_S_always_equal())
258 : _M_t(std::move(__m._M_t), _Key_alloc_type(__a)) { }
259
260 /// Allocator-extended initialier-list constructor.
261 multiset(initializer_list<value_type> __l, const allocator_type& __a)
262 : _M_t(_Key_alloc_type(__a))
263 { _M_t._M_insert_range_equal(__l.begin(), __l.end()); }
264
265 /// Allocator-extended range constructor.
266 template<typename _InputIterator>
267 multiset(_InputIterator __first, _InputIterator __last,
268 const allocator_type& __a)
269 : _M_t(_Key_alloc_type(__a))
270 { _M_t._M_insert_range_equal(__first, __last); }
271
272 /**
273 * The dtor only erases the elements, and note that if the elements
274 * themselves are pointers, the pointed-to memory is not touched in any
275 * way. Managing the pointer is the user's responsibility.
276 */
277 ~multiset() = default;
278 #endif
279
280 /**
281 * @brief %Multiset assignment operator.
282 *
283 * Whether the allocator is copied depends on the allocator traits.
284 */
285 #if __cplusplus < 201103L
286 multiset&
287 operator=(const multiset& __x)
288 {
289 _M_t = __x._M_t;
290 return *this;
291 }
292 #else
293 multiset&
294 operator=(const multiset&) = default;
295
296 /// Move assignment operator.
297 multiset&
298 operator=(multiset&&) = default;
299
300 /**
301 * @brief %Multiset list assignment operator.
302 * @param __l An initializer_list.
303 *
304 * This function fills a %multiset with copies of the elements in the
305 * initializer list @a __l.
306 *
307 * Note that the assignment completely changes the %multiset and
308 * that the resulting %multiset's size is the same as the number
309 * of elements assigned.
310 */
311 multiset&
312 operator=(initializer_list<value_type> __l)
313 {
314 _M_t._M_assign_equal(__l.begin(), __l.end());
315 return *this;
316 }
317 #endif
318
319 // accessors:
320
321 /// Returns the comparison object.
322 key_compare
323 key_comp() const
324 { return _M_t.key_comp(); }
325 /// Returns the comparison object.
326 value_compare
327 value_comp() const
328 { return _M_t.key_comp(); }
329 /// Returns the memory allocation object.
330 allocator_type
331 get_allocator() const _GLIBCXX_NOEXCEPT
332 { return allocator_type(_M_t.get_allocator()); }
333
334 /**
335 * Returns a read-only (constant) iterator that points to the first
336 * element in the %multiset. Iteration is done in ascending order
337 * according to the keys.
338 */
339 iterator
340 begin() const _GLIBCXX_NOEXCEPT
341 { return _M_t.begin(); }
342
343 /**
344 * Returns a read-only (constant) iterator that points one past the last
345 * element in the %multiset. Iteration is done in ascending order
346 * according to the keys.
347 */
348 iterator
349 end() const _GLIBCXX_NOEXCEPT
350 { return _M_t.end(); }
351
352 /**
353 * Returns a read-only (constant) reverse iterator that points to the
354 * last element in the %multiset. Iteration is done in descending order
355 * according to the keys.
356 */
357 reverse_iterator
358 rbegin() const _GLIBCXX_NOEXCEPT
359 { return _M_t.rbegin(); }
360
361 /**
362 * Returns a read-only (constant) reverse iterator that points to the
363 * last element in the %multiset. Iteration is done in descending order
364 * according to the keys.
365 */
366 reverse_iterator
367 rend() const _GLIBCXX_NOEXCEPT
368 { return _M_t.rend(); }
369
370 #if __cplusplus >= 201103L
371 /**
372 * Returns a read-only (constant) iterator that points to the first
373 * element in the %multiset. Iteration is done in ascending order
374 * according to the keys.
375 */
376 iterator
377 cbegin() const noexcept
378 { return _M_t.begin(); }
379
380 /**
381 * Returns a read-only (constant) iterator that points one past the last
382 * element in the %multiset. Iteration is done in ascending order
383 * according to the keys.
384 */
385 iterator
386 cend() const noexcept
387 { return _M_t.end(); }
388
389 /**
390 * Returns a read-only (constant) reverse iterator that points to the
391 * last element in the %multiset. Iteration is done in descending order
392 * according to the keys.
393 */
394 reverse_iterator
395 crbegin() const noexcept
396 { return _M_t.rbegin(); }
397
398 /**
399 * Returns a read-only (constant) reverse iterator that points to the
400 * last element in the %multiset. Iteration is done in descending order
401 * according to the keys.
402 */
403 reverse_iterator
404 crend() const noexcept
405 { return _M_t.rend(); }
406 #endif
407
408 /// Returns true if the %set is empty.
409 _GLIBCXX_NODISCARD bool
410 empty() const _GLIBCXX_NOEXCEPT
411 { return _M_t.empty(); }
412
413 /// Returns the size of the %set.
414 size_type
415 size() const _GLIBCXX_NOEXCEPT
416 { return _M_t.size(); }
417
418 /// Returns the maximum size of the %set.
419 size_type
420 max_size() const _GLIBCXX_NOEXCEPT
421 { return _M_t.max_size(); }
422
423 /**
424 * @brief Swaps data with another %multiset.
425 * @param __x A %multiset of the same element and allocator types.
426 *
427 * This exchanges the elements between two multisets in constant time.
428 * (It is only swapping a pointer, an integer, and an instance of the @c
429 * Compare type (which itself is often stateless and empty), so it should
430 * be quite fast.)
431 * Note that the global std::swap() function is specialized such that
432 * std::swap(s1,s2) will feed to this function.
433 *
434 * Whether the allocators are swapped depends on the allocator traits.
435 */
436 void
437 swap(multiset& __x)
438 _GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Compare>::value)
439 { _M_t.swap(__x._M_t); }
440
441 // insert/erase
442 #if __cplusplus >= 201103L
443 /**
444 * @brief Builds and inserts an element into the %multiset.
445 * @param __args Arguments used to generate the element instance to be
446 * inserted.
447 * @return An iterator that points to the inserted element.
448 *
449 * This function inserts an element into the %multiset. Contrary
450 * to a std::set the %multiset does not rely on unique keys and thus
451 * multiple copies of the same element can be inserted.
452 *
453 * Insertion requires logarithmic time.
454 */
455 template<typename... _Args>
456 iterator
457 emplace(_Args&&... __args)
458 { return _M_t._M_emplace_equal(std::forward<_Args>(__args)...); }
459
460 /**
461 * @brief Builds and inserts an element into the %multiset.
462 * @param __pos An iterator that serves as a hint as to where the
463 * element should be inserted.
464 * @param __args Arguments used to generate the element instance to be
465 * inserted.
466 * @return An iterator that points to the inserted element.
467 *
468 * This function inserts an element into the %multiset. Contrary
469 * to a std::set the %multiset does not rely on unique keys and thus
470 * multiple copies of the same element can be inserted.
471 *
472 * Note that the first parameter is only a hint and can potentially
473 * improve the performance of the insertion process. A bad hint would
474 * cause no gains in efficiency.
475 *
476 * See https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
477 * for more on @a hinting.
478 *
479 * Insertion requires logarithmic time (if the hint is not taken).
480 */
481 template<typename... _Args>
482 iterator
483 emplace_hint(const_iterator __pos, _Args&&... __args)
484 {
485 return _M_t._M_emplace_hint_equal(__pos,
486 std::forward<_Args>(__args)...);
487 }
488 #endif
489
490 /**
491 * @brief Inserts an element into the %multiset.
492 * @param __x Element to be inserted.
493 * @return An iterator that points to the inserted element.
494 *
495 * This function inserts an element into the %multiset. Contrary
496 * to a std::set the %multiset does not rely on unique keys and thus
497 * multiple copies of the same element can be inserted.
498 *
499 * Insertion requires logarithmic time.
500 */
501 iterator
502 insert(const value_type& __x)
503 { return _M_t._M_insert_equal(__x); }
504
505 #if __cplusplus >= 201103L
506 iterator
507 insert(value_type&& __x)
508 { return _M_t._M_insert_equal(std::move(__x)); }
509 #endif
510
511 /**
512 * @brief Inserts an element into the %multiset.
513 * @param __position An iterator that serves as a hint as to where the
514 * element should be inserted.
515 * @param __x Element to be inserted.
516 * @return An iterator that points to the inserted element.
517 *
518 * This function inserts an element into the %multiset. Contrary
519 * to a std::set the %multiset does not rely on unique keys and thus
520 * multiple copies of the same element can be inserted.
521 *
522 * Note that the first parameter is only a hint and can potentially
523 * improve the performance of the insertion process. A bad hint would
524 * cause no gains in efficiency.
525 *
526 * See https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
527 * for more on @a hinting.
528 *
529 * Insertion requires logarithmic time (if the hint is not taken).
530 */
531 iterator
532 insert(const_iterator __position, const value_type& __x)
533 { return _M_t._M_insert_equal_(__position, __x); }
534
535 #if __cplusplus >= 201103L
536 iterator
537 insert(const_iterator __position, value_type&& __x)
538 { return _M_t._M_insert_equal_(__position, std::move(__x)); }
539 #endif
540
541 /**
542 * @brief A template function that tries to insert a range of elements.
543 * @param __first Iterator pointing to the start of the range to be
544 * inserted.
545 * @param __last Iterator pointing to the end of the range.
546 *
547 * Complexity similar to that of the range constructor.
548 */
549 template<typename _InputIterator>
550 void
551 insert(_InputIterator __first, _InputIterator __last)
552 { _M_t._M_insert_range_equal(__first, __last); }
553
554 #if __cplusplus >= 201103L
555 /**
556 * @brief Attempts to insert a list of elements into the %multiset.
557 * @param __l A std::initializer_list<value_type> of elements
558 * to be inserted.
559 *
560 * Complexity similar to that of the range constructor.
561 */
562 void
563 insert(initializer_list<value_type> __l)
564 { this->insert(__l.begin(), __l.end()); }
565 #endif
566
567 #if __cplusplus > 201402L
568 /// Extract a node.
569 node_type
570 extract(const_iterator __pos)
571 {
572 __glibcxx_assert(__pos != end());
573 return _M_t.extract(__pos);
574 }
575
576 /// Extract a node.
577 node_type
578 extract(const key_type& __x)
579 { return _M_t.extract(__x); }
580
581 /// Re-insert an extracted node.
582 iterator
583 insert(node_type&& __nh)
584 { return _M_t._M_reinsert_node_equal(std::move(__nh)); }
585
586 /// Re-insert an extracted node.
587 iterator
588 insert(const_iterator __hint, node_type&& __nh)
589 { return _M_t._M_reinsert_node_hint_equal(__hint, std::move(__nh)); }
590
591 template<typename, typename>
592 friend class std::_Rb_tree_merge_helper;
593
594 template<typename _Compare1>
595 void
596 merge(multiset<_Key, _Compare1, _Alloc>& __source)
597 {
598 using _Merge_helper = _Rb_tree_merge_helper<multiset, _Compare1>;
599 _M_t._M_merge_equal(_Merge_helper::_S_get_tree(__source));
600 }
601
602 template<typename _Compare1>
603 void
604 merge(multiset<_Key, _Compare1, _Alloc>&& __source)
605 { merge(__source); }
606
607 template<typename _Compare1>
608 void
609 merge(set<_Key, _Compare1, _Alloc>& __source)
610 {
611 using _Merge_helper = _Rb_tree_merge_helper<multiset, _Compare1>;
612 _M_t._M_merge_equal(_Merge_helper::_S_get_tree(__source));
613 }
614
615 template<typename _Compare1>
616 void
617 merge(set<_Key, _Compare1, _Alloc>&& __source)
618 { merge(__source); }
619 #endif // C++17
620
621 #if __cplusplus >= 201103L
622 // _GLIBCXX_RESOLVE_LIB_DEFECTS
623 // DR 130. Associative erase should return an iterator.
624 /**
625 * @brief Erases an element from a %multiset.
626 * @param __position An iterator pointing to the element to be erased.
627 * @return An iterator pointing to the element immediately following
628 * @a position prior to the element being erased. If no such
629 * element exists, end() is returned.
630 *
631 * This function erases an element, pointed to by the given iterator,
632 * from a %multiset. Note that this function only erases the element,
633 * and that if the element is itself a pointer, the pointed-to memory is
634 * not touched in any way. Managing the pointer is the user's
635 * responsibility.
636 */
637 _GLIBCXX_ABI_TAG_CXX11
638 iterator
639 erase(const_iterator __position)
640 { return _M_t.erase(__position); }
641 #else
642 /**
643 * @brief Erases an element from a %multiset.
644 * @param __position An iterator pointing to the element to be erased.
645 *
646 * This function erases an element, pointed to by the given iterator,
647 * from a %multiset. Note that this function only erases the element,
648 * and that if the element is itself a pointer, the pointed-to memory is
649 * not touched in any way. Managing the pointer is the user's
650 * responsibility.
651 */
652 void
653 erase(iterator __position)
654 { _M_t.erase(__position); }
655 #endif
656
657 /**
658 * @brief Erases elements according to the provided key.
659 * @param __x Key of element to be erased.
660 * @return The number of elements erased.
661 *
662 * This function erases all elements located by the given key from a
663 * %multiset.
664 * Note that this function only erases the element, and that if
665 * the element is itself a pointer, the pointed-to memory is not touched
666 * in any way. Managing the pointer is the user's responsibility.
667 */
668 size_type
669 erase(const key_type& __x)
670 { return _M_t.erase(__x); }
671
672 #if __cplusplus >= 201103L
673 // _GLIBCXX_RESOLVE_LIB_DEFECTS
674 // DR 130. Associative erase should return an iterator.
675 /**
676 * @brief Erases a [first,last) range of elements from a %multiset.
677 * @param __first Iterator pointing to the start of the range to be
678 * erased.
679 * @param __last Iterator pointing to the end of the range to
680 * be erased.
681 * @return The iterator @a last.
682 *
683 * This function erases a sequence of elements from a %multiset.
684 * Note that this function only erases the elements, and that if
685 * the elements themselves are pointers, the pointed-to memory is not
686 * touched in any way. Managing the pointer is the user's
687 * responsibility.
688 */
689 _GLIBCXX_ABI_TAG_CXX11
690 iterator
691 erase(const_iterator __first, const_iterator __last)
692 { return _M_t.erase(__first, __last); }
693 #else
694 /**
695 * @brief Erases a [first,last) range of elements from a %multiset.
696 * @param first Iterator pointing to the start of the range to be
697 * erased.
698 * @param last Iterator pointing to the end of the range to be erased.
699 *
700 * This function erases a sequence of elements from a %multiset.
701 * Note that this function only erases the elements, and that if
702 * the elements themselves are pointers, the pointed-to memory is not
703 * touched in any way. Managing the pointer is the user's
704 * responsibility.
705 */
706 void
707 erase(iterator __first, iterator __last)
708 { _M_t.erase(__first, __last); }
709 #endif
710
711 /**
712 * Erases all elements in a %multiset. Note that this function only
713 * erases the elements, and that if the elements themselves are pointers,
714 * the pointed-to memory is not touched in any way. Managing the pointer
715 * is the user's responsibility.
716 */
717 void
718 clear() _GLIBCXX_NOEXCEPT
719 { _M_t.clear(); }
720
721 // multiset operations:
722
723 //@{
724 /**
725 * @brief Finds the number of elements with given key.
726 * @param __x Key of elements to be located.
727 * @return Number of elements with specified key.
728 */
729 size_type
730 count(const key_type& __x) const
731 { return _M_t.count(__x); }
732
733 #if __cplusplus > 201103L
734 template<typename _Kt>
735 auto
736 count(const _Kt& __x) const -> decltype(_M_t._M_count_tr(__x))
737 { return _M_t._M_count_tr(__x); }
738 #endif
739 //@}
740
741 #if __cplusplus > 201703L
742 //@{
743 /**
744 * @brief Finds whether an element with the given key exists.
745 * @param __x Key of elements to be located.
746 * @return True if there is any element with the specified key.
747 */
748 bool
749 contains(const key_type& __x) const
750 { return _M_t.find(__x) != _M_t.end(); }
751
752 template<typename _Kt>
753 auto
754 contains(const _Kt& __x) const
755 -> decltype(_M_t._M_find_tr(__x), void(), true)
756 { return _M_t._M_find_tr(__x) != _M_t.end(); }
757 //@}
758 #endif
759
760 // _GLIBCXX_RESOLVE_LIB_DEFECTS
761 // 214. set::find() missing const overload
762 //@{
763 /**
764 * @brief Tries to locate an element in a %set.
765 * @param __x Element to be located.
766 * @return Iterator pointing to sought-after element, or end() if not
767 * found.
768 *
769 * This function takes a key and tries to locate the element with which
770 * the key matches. If successful the function returns an iterator
771 * pointing to the sought after element. If unsuccessful it returns the
772 * past-the-end ( @c end() ) iterator.
773 */
774 iterator
775 find(const key_type& __x)
776 { return _M_t.find(__x); }
777
778 const_iterator
779 find(const key_type& __x) const
780 { return _M_t.find(__x); }
781
782 #if __cplusplus > 201103L
783 template<typename _Kt>
784 auto
785 find(const _Kt& __x)
786 -> decltype(iterator{_M_t._M_find_tr(__x)})
787 { return iterator{_M_t._M_find_tr(__x)}; }
788
789 template<typename _Kt>
790 auto
791 find(const _Kt& __x) const
792 -> decltype(const_iterator{_M_t._M_find_tr(__x)})
793 { return const_iterator{_M_t._M_find_tr(__x)}; }
794 #endif
795 //@}
796
797 //@{
798 /**
799 * @brief Finds the beginning of a subsequence matching given key.
800 * @param __x Key to be located.
801 * @return Iterator pointing to first element equal to or greater
802 * than key, or end().
803 *
804 * This function returns the first element of a subsequence of elements
805 * that matches the given key. If unsuccessful it returns an iterator
806 * pointing to the first element that has a greater value than given key
807 * or end() if no such element exists.
808 */
809 iterator
810 lower_bound(const key_type& __x)
811 { return _M_t.lower_bound(__x); }
812
813 const_iterator
814 lower_bound(const key_type& __x) const
815 { return _M_t.lower_bound(__x); }
816
817 #if __cplusplus > 201103L
818 template<typename _Kt>
819 auto
820 lower_bound(const _Kt& __x)
821 -> decltype(iterator(_M_t._M_lower_bound_tr(__x)))
822 { return iterator(_M_t._M_lower_bound_tr(__x)); }
823
824 template<typename _Kt>
825 auto
826 lower_bound(const _Kt& __x) const
827 -> decltype(iterator(_M_t._M_lower_bound_tr(__x)))
828 { return iterator(_M_t._M_lower_bound_tr(__x)); }
829 #endif
830 //@}
831
832 //@{
833 /**
834 * @brief Finds the end of a subsequence matching given key.
835 * @param __x Key to be located.
836 * @return Iterator pointing to the first element
837 * greater than key, or end().
838 */
839 iterator
840 upper_bound(const key_type& __x)
841 { return _M_t.upper_bound(__x); }
842
843 const_iterator
844 upper_bound(const key_type& __x) const
845 { return _M_t.upper_bound(__x); }
846
847 #if __cplusplus > 201103L
848 template<typename _Kt>
849 auto
850 upper_bound(const _Kt& __x)
851 -> decltype(iterator(_M_t._M_upper_bound_tr(__x)))
852 { return iterator(_M_t._M_upper_bound_tr(__x)); }
853
854 template<typename _Kt>
855 auto
856 upper_bound(const _Kt& __x) const
857 -> decltype(iterator(_M_t._M_upper_bound_tr(__x)))
858 { return iterator(_M_t._M_upper_bound_tr(__x)); }
859 #endif
860 //@}
861
862 //@{
863 /**
864 * @brief Finds a subsequence matching given key.
865 * @param __x Key to be located.
866 * @return Pair of iterators that possibly points to the subsequence
867 * matching given key.
868 *
869 * This function is equivalent to
870 * @code
871 * std::make_pair(c.lower_bound(val),
872 * c.upper_bound(val))
873 * @endcode
874 * (but is faster than making the calls separately).
875 *
876 * This function probably only makes sense for multisets.
877 */
878 std::pair<iterator, iterator>
879 equal_range(const key_type& __x)
880 { return _M_t.equal_range(__x); }
881
882 std::pair<const_iterator, const_iterator>
883 equal_range(const key_type& __x) const
884 { return _M_t.equal_range(__x); }
885
886 #if __cplusplus > 201103L
887 template<typename _Kt>
888 auto
889 equal_range(const _Kt& __x)
890 -> decltype(pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)))
891 { return pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)); }
892
893 template<typename _Kt>
894 auto
895 equal_range(const _Kt& __x) const
896 -> decltype(pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)))
897 { return pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)); }
898 #endif
899 //@}
900
901 template<typename _K1, typename _C1, typename _A1>
902 friend bool
903 operator==(const multiset<_K1, _C1, _A1>&,
904 const multiset<_K1, _C1, _A1>&);
905
906 #if __cpp_lib_three_way_comparison
907 template<typename _K1, typename _C1, typename _A1>
908 friend __detail::__synth3way_t<_K1>
909 operator<=>(const multiset<_K1, _C1, _A1>&,
910 const multiset<_K1, _C1, _A1>&);
911 #else
912 template<typename _K1, typename _C1, typename _A1>
913 friend bool
914 operator< (const multiset<_K1, _C1, _A1>&,
915 const multiset<_K1, _C1, _A1>&);
916 #endif
917 };
918
919 #if __cpp_deduction_guides >= 201606
920
921 template<typename _InputIterator,
922 typename _Compare =
923 less<typename iterator_traits<_InputIterator>::value_type>,
924 typename _Allocator =
925 allocator<typename iterator_traits<_InputIterator>::value_type>,
926 typename = _RequireInputIter<_InputIterator>,
927 typename = _RequireNotAllocator<_Compare>,
928 typename = _RequireAllocator<_Allocator>>
929 multiset(_InputIterator, _InputIterator,
930 _Compare = _Compare(), _Allocator = _Allocator())
931 -> multiset<typename iterator_traits<_InputIterator>::value_type,
932 _Compare, _Allocator>;
933
934 template<typename _Key,
935 typename _Compare = less<_Key>,
936 typename _Allocator = allocator<_Key>,
937 typename = _RequireNotAllocator<_Compare>,
938 typename = _RequireAllocator<_Allocator>>
939 multiset(initializer_list<_Key>,
940 _Compare = _Compare(), _Allocator = _Allocator())
941 -> multiset<_Key, _Compare, _Allocator>;
942
943 template<typename _InputIterator, typename _Allocator,
944 typename = _RequireInputIter<_InputIterator>,
945 typename = _RequireAllocator<_Allocator>>
946 multiset(_InputIterator, _InputIterator, _Allocator)
947 -> multiset<typename iterator_traits<_InputIterator>::value_type,
948 less<typename iterator_traits<_InputIterator>::value_type>,
949 _Allocator>;
950
951 template<typename _Key, typename _Allocator,
952 typename = _RequireAllocator<_Allocator>>
953 multiset(initializer_list<_Key>, _Allocator)
954 -> multiset<_Key, less<_Key>, _Allocator>;
955
956 #endif // deduction guides
957
958 /**
959 * @brief Multiset equality comparison.
960 * @param __x A %multiset.
961 * @param __y A %multiset of the same type as @a __x.
962 * @return True iff the size and elements of the multisets are equal.
963 *
964 * This is an equivalence relation. It is linear in the size of the
965 * multisets.
966 * Multisets are considered equivalent if their sizes are equal, and if
967 * corresponding elements compare equal.
968 */
969 template<typename _Key, typename _Compare, typename _Alloc>
970 inline bool
971 operator==(const multiset<_Key, _Compare, _Alloc>& __x,
972 const multiset<_Key, _Compare, _Alloc>& __y)
973 { return __x._M_t == __y._M_t; }
974
975 #if __cpp_lib_three_way_comparison
976 /**
977 * @brief Multiset ordering relation.
978 * @param __x A `multiset`.
979 * @param __y A `multiset` of the same type as `x`.
980 * @return A value indicating whether `__x` is less than, equal to,
981 * greater than, or incomparable with `__y`.
982 *
983 * This is a total ordering relation. It is linear in the size of the
984 * maps. The elements must be comparable with @c <.
985 *
986 * See `std::lexicographical_compare_three_way()` for how the determination
987 * is made. This operator is used to synthesize relational operators like
988 * `<` and `>=` etc.
989 */
990 template<typename _Key, typename _Compare, typename _Alloc>
991 inline __detail::__synth3way_t<_Key>
992 operator<=>(const multiset<_Key, _Compare, _Alloc>& __x,
993 const multiset<_Key, _Compare, _Alloc>& __y)
994 { return __x._M_t <=> __y._M_t; }
995 #else
996 /**
997 * @brief Multiset ordering relation.
998 * @param __x A %multiset.
999 * @param __y A %multiset of the same type as @a __x.
1000 * @return True iff @a __x is lexicographically less than @a __y.
1001 *
1002 * This is a total ordering relation. It is linear in the size of the
1003 * sets. The elements must be comparable with @c <.
1004 *
1005 * See std::lexicographical_compare() for how the determination is made.
1006 */
1007 template<typename _Key, typename _Compare, typename _Alloc>
1008 inline bool
1009 operator<(const multiset<_Key, _Compare, _Alloc>& __x,
1010 const multiset<_Key, _Compare, _Alloc>& __y)
1011 { return __x._M_t < __y._M_t; }
1012
1013 /// Returns !(x == y).
1014 template<typename _Key, typename _Compare, typename _Alloc>
1015 inline bool
1016 operator!=(const multiset<_Key, _Compare, _Alloc>& __x,
1017 const multiset<_Key, _Compare, _Alloc>& __y)
1018 { return !(__x == __y); }
1019
1020 /// Returns y < x.
1021 template<typename _Key, typename _Compare, typename _Alloc>
1022 inline bool
1023 operator>(const multiset<_Key,_Compare,_Alloc>& __x,
1024 const multiset<_Key,_Compare,_Alloc>& __y)
1025 { return __y < __x; }
1026
1027 /// Returns !(y < x)
1028 template<typename _Key, typename _Compare, typename _Alloc>
1029 inline bool
1030 operator<=(const multiset<_Key, _Compare, _Alloc>& __x,
1031 const multiset<_Key, _Compare, _Alloc>& __y)
1032 { return !(__y < __x); }
1033
1034 /// Returns !(x < y)
1035 template<typename _Key, typename _Compare, typename _Alloc>
1036 inline bool
1037 operator>=(const multiset<_Key, _Compare, _Alloc>& __x,
1038 const multiset<_Key, _Compare, _Alloc>& __y)
1039 { return !(__x < __y); }
1040 #endif // three-way comparison
1041
1042 /// See std::multiset::swap().
1043 template<typename _Key, typename _Compare, typename _Alloc>
1044 inline void
1045 swap(multiset<_Key, _Compare, _Alloc>& __x,
1046 multiset<_Key, _Compare, _Alloc>& __y)
1047 _GLIBCXX_NOEXCEPT_IF(noexcept(__x.swap(__y)))
1048 { __x.swap(__y); }
1049
1050 _GLIBCXX_END_NAMESPACE_CONTAINER
1051
1052 #if __cplusplus > 201402L
1053 // Allow std::multiset access to internals of compatible sets.
1054 template<typename _Val, typename _Cmp1, typename _Alloc, typename _Cmp2>
1055 struct
1056 _Rb_tree_merge_helper<_GLIBCXX_STD_C::multiset<_Val, _Cmp1, _Alloc>,
1057 _Cmp2>
1058 {
1059 private:
1060 friend class _GLIBCXX_STD_C::multiset<_Val, _Cmp1, _Alloc>;
1061
1062 static auto&
1063 _S_get_tree(_GLIBCXX_STD_C::set<_Val, _Cmp2, _Alloc>& __set)
1064 { return __set._M_t; }
1065
1066 static auto&
1067 _S_get_tree(_GLIBCXX_STD_C::multiset<_Val, _Cmp2, _Alloc>& __set)
1068 { return __set._M_t; }
1069 };
1070 #endif // C++17
1071
1072 _GLIBCXX_END_NAMESPACE_VERSION
1073 } // namespace std
1074
1075 #endif /* _STL_MULTISET_H */
1076