libstdc++-v3/include/bits/stl_multiset.h

   1 // Multiset implementation -*- C++ -*-
   2
   3 // Copyright (C) 2001-2017 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    *
  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     public:
 110       // typedefs:
 111       typedef _Key     key_type;
 112       typedef _Key     value_type;
 113       typedef _Compare key_compare;
 114       typedef _Compare value_compare;
 115       typedef _Alloc   allocator_type;
 116
 117     private:
 118       /// This turns a red-black tree into a [multi]set.
 119       typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
 120         rebind<_Key>::other _Key_alloc_type;
 121
 122       typedef _Rb_tree<key_type, value_type, _Identity<value_type>,
 123                        key_compare, _Key_alloc_type> _Rep_type;
 124       /// The actual tree structure.
 125       _Rep_type _M_t;
 126
 127       typedef __gnu_cxx::__alloc_traits<_Key_alloc_type> _Alloc_traits;
 128
 129     public:
 130       typedef typename _Alloc_traits::pointer            pointer;
 131       typedef typename _Alloc_traits::const_pointer      const_pointer;
 132       typedef typename _Alloc_traits::reference          reference;
 133       typedef typename _Alloc_traits::const_reference    const_reference;
 134       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 135       // DR 103. set::iterator is required to be modifiable,
 136       // but this allows modification of keys.
 137       typedef typename _Rep_type::const_iterator         iterator;
 138       typedef typename _Rep_type::const_iterator         const_iterator;
 139       typedef typename _Rep_type::const_reverse_iterator reverse_iterator;
 140       typedef typename _Rep_type::const_reverse_iterator const_reverse_iterator;
 141       typedef typename _Rep_type::size_type              size_type;
 142       typedef typename _Rep_type::difference_type        difference_type;
 143
 144 #if __cplusplus > 201402L
 145       using node_type = typename _Rep_type::node_type;
 146 #endif
 147
 148       // allocation/deallocation
 149       /**
 150        *  @brief  Default constructor creates no elements.
 151        */
 152 #if __cplusplus < 201103L
 153       multiset() : _M_t() { }
 154 #else
 155       multiset() = default;
 156 #endif
 157
 158       /**
 159        *  @brief  Creates a %multiset with no elements.
 160        *  @param  __comp  Comparator to use.
 161        *  @param  __a  An allocator object.
 162        */
 163       explicit
 164       multiset(const _Compare& __comp,
 165                const allocator_type& __a = allocator_type())
 166       : _M_t(__comp, _Key_alloc_type(__a)) { }
 167
 168       /**
 169        *  @brief  Builds a %multiset from a range.
 170        *  @param  __first  An input iterator.
 171        *  @param  __last  An input iterator.
 172        *
 173        *  Create a %multiset consisting of copies of the elements from
 174        *  [first,last).  This is linear in N if the range is already sorted,
 175        *  and NlogN otherwise (where N is distance(__first,__last)).
 176        */
 177       template<typename _InputIterator>
 178         multiset(_InputIterator __first, _InputIterator __last)
 179         : _M_t()
 180         { _M_t._M_insert_equal(__first, __last); }
 181
 182       /**
 183        *  @brief  Builds a %multiset from a range.
 184        *  @param  __first  An input iterator.
 185        *  @param  __last  An input iterator.
 186        *  @param  __comp  A comparison functor.
 187        *  @param  __a  An allocator object.
 188        *
 189        *  Create a %multiset consisting of copies of the elements from
 190        *  [__first,__last).  This is linear in N if the range is already sorted,
 191        *  and NlogN otherwise (where N is distance(__first,__last)).
 192        */
 193       template<typename _InputIterator>
 194         multiset(_InputIterator __first, _InputIterator __last,
 195                  const _Compare& __comp,
 196                  const allocator_type& __a = allocator_type())
 197         : _M_t(__comp, _Key_alloc_type(__a))
 198         { _M_t._M_insert_equal(__first, __last); }
 199
 200       /**
 201        *  @brief  %Multiset copy constructor.
 202        *
 203        *  Whether the allocator is copied depends on the allocator traits.
 204        */
 205 #if __cplusplus < 201103L
 206       multiset(const multiset& __x)
 207       : _M_t(__x._M_t) { }
 208 #else
 209       multiset(const multiset&) = default;
 210
 211      /**
 212        *  @brief  %Multiset move constructor.
 213        *
 214        *  The newly-created %multiset contains the exact contents of the
 215        *  moved instance. The moved instance is a valid, but unspecified
 216        *  %multiset.
 217        */
 218       multiset(multiset&&) = default;
 219
 220       /**
 221        *  @brief  Builds a %multiset from an initializer_list.
 222        *  @param  __l  An initializer_list.
 223        *  @param  __comp  A comparison functor.
 224        *  @param  __a  An allocator object.
 225        *
 226        *  Create a %multiset consisting of copies of the elements from
 227        *  the list.  This is linear in N if the list is already sorted,
 228        *  and NlogN otherwise (where N is @a __l.size()).
 229        */
 230       multiset(initializer_list<value_type> __l,
 231                const _Compare& __comp = _Compare(),
 232                const allocator_type& __a = allocator_type())
 233       : _M_t(__comp, _Key_alloc_type(__a))
 234       { _M_t._M_insert_equal(__l.begin(), __l.end()); }
 235
 236       /// Allocator-extended default constructor.
 237       explicit
 238       multiset(const allocator_type& __a)
 239       : _M_t(_Compare(), _Key_alloc_type(__a)) { }
 240
 241       /// Allocator-extended copy constructor.
 242       multiset(const multiset& __m, const allocator_type& __a)
 243       : _M_t(__m._M_t, _Key_alloc_type(__a)) { }
 244
 245       /// Allocator-extended move constructor.
 246       multiset(multiset&& __m, const allocator_type& __a)
 247       noexcept(is_nothrow_copy_constructible<_Compare>::value
 248                && _Alloc_traits::_S_always_equal())
 249       : _M_t(std::move(__m._M_t), _Key_alloc_type(__a)) { }
 250
 251       /// Allocator-extended initialier-list constructor.
 252       multiset(initializer_list<value_type> __l, const allocator_type& __a)
 253       : _M_t(_Compare(), _Key_alloc_type(__a))
 254       { _M_t._M_insert_equal(__l.begin(), __l.end()); }
 255
 256       /// Allocator-extended range constructor.
 257       template<typename _InputIterator>
 258         multiset(_InputIterator __first, _InputIterator __last,
 259                  const allocator_type& __a)
 260         : _M_t(_Compare(), _Key_alloc_type(__a))
 261         { _M_t._M_insert_equal(__first, __last); }
 262
 263       /**
 264        *  The dtor only erases the elements, and note that if the elements
 265        *  themselves are pointers, the pointed-to memory is not touched in any
 266        *  way. Managing the pointer is the user's responsibility.
 267        */
 268       ~multiset() = default;
 269 #endif
 270
 271       /**
 272        *  @brief  %Multiset assignment operator.
 273        *
 274        *  Whether the allocator is copied depends on the allocator traits.
 275        */
 276 #if __cplusplus < 201103L
 277       multiset&
 278       operator=(const multiset& __x)
 279       {
 280         _M_t = __x._M_t;
 281         return *this;
 282       }
 283 #else
 284       multiset&
 285       operator=(const multiset&) = default;
 286
 287       /// Move assignment operator.
 288       multiset&
 289       operator=(multiset&&) = default;
 290
 291       /**
 292        *  @brief  %Multiset list assignment operator.
 293        *  @param  __l  An initializer_list.
 294        *
 295        *  This function fills a %multiset with copies of the elements in the
 296        *  initializer list @a __l.
 297        *
 298        *  Note that the assignment completely changes the %multiset and
 299        *  that the resulting %multiset's size is the same as the number
 300        *  of elements assigned.
 301        */
 302       multiset&
 303       operator=(initializer_list<value_type> __l)
 304       {
 305         _M_t._M_assign_equal(__l.begin(), __l.end());
 306         return *this;
 307       }
 308 #endif
 309
 310       // accessors:
 311
 312       ///  Returns the comparison object.
 313       key_compare
 314       key_comp() const
 315       { return _M_t.key_comp(); }
 316       ///  Returns the comparison object.
 317       value_compare
 318       value_comp() const
 319       { return _M_t.key_comp(); }
 320       ///  Returns the memory allocation object.
 321       allocator_type
 322       get_allocator() const _GLIBCXX_NOEXCEPT
 323       { return allocator_type(_M_t.get_allocator()); }
 324
 325       /**
 326        *  Returns a read-only (constant) iterator that points to the first
 327        *  element in the %multiset.  Iteration is done in ascending order
 328        *  according to the keys.
 329        */
 330       iterator
 331       begin() const _GLIBCXX_NOEXCEPT
 332       { return _M_t.begin(); }
 333
 334       /**
 335        *  Returns a read-only (constant) iterator that points one past the last
 336        *  element in the %multiset.  Iteration is done in ascending order
 337        *  according to the keys.
 338        */
 339       iterator
 340       end() const _GLIBCXX_NOEXCEPT
 341       { return _M_t.end(); }
 342
 343       /**
 344        *  Returns a read-only (constant) reverse iterator that points to the
 345        *  last element in the %multiset.  Iteration is done in descending order
 346        *  according to the keys.
 347        */
 348       reverse_iterator
 349       rbegin() const _GLIBCXX_NOEXCEPT
 350       { return _M_t.rbegin(); }
 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       rend() const _GLIBCXX_NOEXCEPT
 359       { return _M_t.rend(); }
 360
 361 #if __cplusplus >= 201103L
 362       /**
 363        *  Returns a read-only (constant) iterator that points to the first
 364        *  element in the %multiset.  Iteration is done in ascending order
 365        *  according to the keys.
 366        */
 367       iterator
 368       cbegin() const noexcept
 369       { return _M_t.begin(); }
 370
 371       /**
 372        *  Returns a read-only (constant) iterator that points one past the last
 373        *  element in the %multiset.  Iteration is done in ascending order
 374        *  according to the keys.
 375        */
 376       iterator
 377       cend() const noexcept
 378       { return _M_t.end(); }
 379
 380       /**
 381        *  Returns a read-only (constant) reverse iterator that points to the
 382        *  last element in the %multiset.  Iteration is done in descending order
 383        *  according to the keys.
 384        */
 385       reverse_iterator
 386       crbegin() const noexcept
 387       { return _M_t.rbegin(); }
 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       crend() const noexcept
 396       { return _M_t.rend(); }
 397 #endif
 398
 399       ///  Returns true if the %set is empty.
 400       bool
 401       empty() const _GLIBCXX_NOEXCEPT
 402       { return _M_t.empty(); }
 403
 404       ///  Returns the size of the %set.
 405       size_type
 406       size() const _GLIBCXX_NOEXCEPT
 407       { return _M_t.size(); }
 408
 409       ///  Returns the maximum size of the %set.
 410       size_type
 411       max_size() const _GLIBCXX_NOEXCEPT
 412       { return _M_t.max_size(); }
 413
 414       /**
 415        *  @brief  Swaps data with another %multiset.
 416        *  @param  __x  A %multiset of the same element and allocator types.
 417        *
 418        *  This exchanges the elements between two multisets in constant time.
 419        *  (It is only swapping a pointer, an integer, and an instance of the @c
 420        *  Compare type (which itself is often stateless and empty), so it should
 421        *  be quite fast.)
 422        *  Note that the global std::swap() function is specialized such that
 423        *  std::swap(s1,s2) will feed to this function.
 424        *
 425        *  Whether the allocators are swapped depends on the allocator traits.
 426        */
 427       void
 428       swap(multiset& __x)
 429       _GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Compare>::value)
 430       { _M_t.swap(__x._M_t); }
 431
 432       // insert/erase
 433 #if __cplusplus >= 201103L
 434       /**
 435        *  @brief Builds and inserts an element into the %multiset.
 436        *  @param  __args  Arguments used to generate the element instance to be
 437        *                 inserted.
 438        *  @return An iterator that points to the inserted element.
 439        *
 440        *  This function inserts an element into the %multiset.  Contrary
 441        *  to a std::set the %multiset does not rely on unique keys and thus
 442        *  multiple copies of the same element can be inserted.
 443        *
 444        *  Insertion requires logarithmic time.
 445        */
 446       template<typename... _Args>
 447         iterator
 448         emplace(_Args&&... __args)
 449         { return _M_t._M_emplace_equal(std::forward<_Args>(__args)...); }
 450
 451       /**
 452        *  @brief Builds and inserts an element into the %multiset.
 453        *  @param  __pos  An iterator that serves as a hint as to where the
 454        *                element should be inserted.
 455        *  @param  __args  Arguments used to generate the element instance to be
 456        *                 inserted.
 457        *  @return An iterator that points to the inserted element.
 458        *
 459        *  This function inserts an element into the %multiset.  Contrary
 460        *  to a std::set the %multiset does not rely on unique keys and thus
 461        *  multiple copies of the same element can be inserted.
 462        *
 463        *  Note that the first parameter is only a hint and can potentially
 464        *  improve the performance of the insertion process.  A bad hint would
 465        *  cause no gains in efficiency.
 466        *
 467        *  See https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
 468        *  for more on @a hinting.
 469        *
 470        *  Insertion requires logarithmic time (if the hint is not taken).
 471        */
 472       template<typename... _Args>
 473         iterator
 474         emplace_hint(const_iterator __pos, _Args&&... __args)
 475         {
 476           return _M_t._M_emplace_hint_equal(__pos,
 477                                             std::forward<_Args>(__args)...);
 478         }
 479 #endif
 480
 481       /**
 482        *  @brief Inserts an element into the %multiset.
 483        *  @param  __x  Element to be inserted.
 484        *  @return An iterator that points to the inserted element.
 485        *
 486        *  This function inserts an element into the %multiset.  Contrary
 487        *  to a std::set the %multiset does not rely on unique keys and thus
 488        *  multiple copies of the same element can be inserted.
 489        *
 490        *  Insertion requires logarithmic time.
 491        */
 492       iterator
 493       insert(const value_type& __x)
 494       { return _M_t._M_insert_equal(__x); }
 495
 496 #if __cplusplus >= 201103L
 497       iterator
 498       insert(value_type&& __x)
 499       { return _M_t._M_insert_equal(std::move(__x)); }
 500 #endif
 501
 502       /**
 503        *  @brief Inserts an element into the %multiset.
 504        *  @param  __position  An iterator that serves as a hint as to where the
 505        *                    element should be inserted.
 506        *  @param  __x  Element to be inserted.
 507        *  @return An iterator that points to the inserted element.
 508        *
 509        *  This function inserts an element into the %multiset.  Contrary
 510        *  to a std::set the %multiset does not rely on unique keys and thus
 511        *  multiple copies of the same element can be inserted.
 512        *
 513        *  Note that the first parameter is only a hint and can potentially
 514        *  improve the performance of the insertion process.  A bad hint would
 515        *  cause no gains in efficiency.
 516        *
 517        *  See https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
 518        *  for more on @a hinting.
 519        *
 520        *  Insertion requires logarithmic time (if the hint is not taken).
 521        */
 522       iterator
 523       insert(const_iterator __position, const value_type& __x)
 524       { return _M_t._M_insert_equal_(__position, __x); }
 525
 526 #if __cplusplus >= 201103L
 527       iterator
 528       insert(const_iterator __position, value_type&& __x)
 529       { return _M_t._M_insert_equal_(__position, std::move(__x)); }
 530 #endif
 531
 532       /**
 533        *  @brief A template function that tries to insert a range of elements.
 534        *  @param  __first  Iterator pointing to the start of the range to be
 535        *                   inserted.
 536        *  @param  __last  Iterator pointing to the end of the range.
 537        *
 538        *  Complexity similar to that of the range constructor.
 539        */
 540       template<typename _InputIterator>
 541         void
 542         insert(_InputIterator __first, _InputIterator __last)
 543         { _M_t._M_insert_equal(__first, __last); }
 544
 545 #if __cplusplus >= 201103L
 546       /**
 547        *  @brief Attempts to insert a list of elements into the %multiset.
 548        *  @param  __l  A std::initializer_list<value_type> of elements
 549        *               to be inserted.
 550        *
 551        *  Complexity similar to that of the range constructor.
 552        */
 553       void
 554       insert(initializer_list<value_type> __l)
 555       { this->insert(__l.begin(), __l.end()); }
 556 #endif
 557
 558 #if __cplusplus > 201402L
 559       /// Extract a node.
 560       node_type
 561       extract(const_iterator __pos)
 562       {
 563         __glibcxx_assert(__pos != end());
 564         return _M_t.extract(__pos);
 565       }
 566
 567       /// Extract a node.
 568       node_type
 569       extract(const key_type& __x)
 570       { return _M_t.extract(__x); }
 571
 572       /// Re-insert an extracted node.
 573       iterator
 574       insert(node_type&& __nh)
 575       { return _M_t._M_reinsert_node_equal(std::move(__nh)); }
 576
 577       /// Re-insert an extracted node.
 578       iterator
 579       insert(const_iterator __hint, node_type&& __nh)
 580       { return _M_t._M_reinsert_node_hint_equal(__hint, std::move(__nh)); }
 581
 582       template<typename, typename>
 583         friend class _Rb_tree_merge_helper;
 584
 585       template<typename _Compare1>
 586         void
 587         merge(multiset<_Key, _Compare1, _Alloc>& __source)
 588         {
 589           using _Merge_helper = _Rb_tree_merge_helper<multiset, _Compare1>;
 590           _M_t._M_merge_equal(_Merge_helper::_S_get_tree(__source));
 591         }
 592
 593       template<typename _Compare1>
 594         void
 595         merge(multiset<_Key, _Compare1, _Alloc>&& __source)
 596         { merge(__source); }
 597
 598       template<typename _Compare1>
 599         void
 600         merge(set<_Key, _Compare1, _Alloc>& __source)
 601         {
 602           using _Merge_helper = _Rb_tree_merge_helper<multiset, _Compare1>;
 603           _M_t._M_merge_equal(_Merge_helper::_S_get_tree(__source));
 604         }
 605
 606       template<typename _Compare1>
 607         void
 608         merge(set<_Key, _Compare1, _Alloc>&& __source)
 609         { merge(__source); }
 610 #endif // C++17
 611
 612 #if __cplusplus >= 201103L
 613       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 614       // DR 130. Associative erase should return an iterator.
 615       /**
 616        *  @brief Erases an element from a %multiset.
 617        *  @param  __position  An iterator pointing to the element to be erased.
 618        *  @return An iterator pointing to the element immediately following
 619        *          @a position prior to the element being erased. If no such
 620        *          element exists, end() is returned.
 621        *
 622        *  This function erases an element, pointed to by the given iterator,
 623        *  from a %multiset.  Note that this function only erases the element,
 624        *  and that if the element is itself a pointer, the pointed-to memory is
 625        *  not touched in any way.  Managing the pointer is the user's
 626        *  responsibility.
 627        */
 628       _GLIBCXX_ABI_TAG_CXX11
 629       iterator
 630       erase(const_iterator __position)
 631       { return _M_t.erase(__position); }
 632 #else
 633       /**
 634        *  @brief Erases an element from a %multiset.
 635        *  @param  __position  An iterator pointing to the element to be erased.
 636        *
 637        *  This function erases an element, pointed to by the given iterator,
 638        *  from a %multiset.  Note that this function only erases the element,
 639        *  and that if the element is itself a pointer, the pointed-to memory is
 640        *  not touched in any way.  Managing the pointer is the user's
 641        *  responsibility.
 642        */
 643       void
 644       erase(iterator __position)
 645       { _M_t.erase(__position); }
 646 #endif
 647
 648       /**
 649        *  @brief Erases elements according to the provided key.
 650        *  @param  __x  Key of element to be erased.
 651        *  @return  The number of elements erased.
 652        *
 653        *  This function erases all elements located by the given key from a
 654        *  %multiset.
 655        *  Note that this function only erases the element, and that if
 656        *  the element is itself a pointer, the pointed-to memory is not touched
 657        *  in any way.  Managing the pointer is the user's responsibility.
 658        */
 659       size_type
 660       erase(const key_type& __x)
 661       { return _M_t.erase(__x); }
 662
 663 #if __cplusplus >= 201103L
 664       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 665       // DR 130. Associative erase should return an iterator.
 666       /**
 667        *  @brief Erases a [first,last) range of elements from a %multiset.
 668        *  @param  __first  Iterator pointing to the start of the range to be
 669        *                   erased.
 670        *  @param __last Iterator pointing to the end of the range to
 671        *                be erased.
 672        *  @return The iterator @a last.
 673        *
 674        *  This function erases a sequence of elements from a %multiset.
 675        *  Note that this function only erases the elements, and that if
 676        *  the elements themselves are pointers, the pointed-to memory is not
 677        *  touched in any way.  Managing the pointer is the user's
 678        *  responsibility.
 679        */
 680       _GLIBCXX_ABI_TAG_CXX11
 681       iterator
 682       erase(const_iterator __first, const_iterator __last)
 683       { return _M_t.erase(__first, __last); }
 684 #else
 685       /**
 686        *  @brief Erases a [first,last) range of elements from a %multiset.
 687        *  @param  first  Iterator pointing to the start of the range to be
 688        *                 erased.
 689        *  @param  last  Iterator pointing to the end of the range to be erased.
 690        *
 691        *  This function erases a sequence of elements from a %multiset.
 692        *  Note that this function only erases the elements, and that if
 693        *  the elements themselves are pointers, the pointed-to memory is not
 694        *  touched in any way.  Managing the pointer is the user's
 695        *  responsibility.
 696        */
 697       void
 698       erase(iterator __first, iterator __last)
 699       { _M_t.erase(__first, __last); }
 700 #endif
 701
 702       /**
 703        *  Erases all elements in a %multiset.  Note that this function only
 704        *  erases the elements, and that if the elements themselves are pointers,
 705        *  the pointed-to memory is not touched in any way.  Managing the pointer
 706        *  is the user's responsibility.
 707        */
 708       void
 709       clear() _GLIBCXX_NOEXCEPT
 710       { _M_t.clear(); }
 711
 712       // multiset operations:
 713
 714       //@{
 715       /**
 716        *  @brief Finds the number of elements with given key.
 717        *  @param  __x  Key of elements to be located.
 718        *  @return Number of elements with specified key.
 719        */
 720       size_type
 721       count(const key_type& __x) const
 722       { return _M_t.count(__x); }
 723
 724 #if __cplusplus > 201103L
 725       template<typename _Kt>
 726         auto
 727         count(const _Kt& __x) const -> decltype(_M_t._M_count_tr(__x))
 728         { return _M_t._M_count_tr(__x); }
 729 #endif
 730       //@}
 731
 732       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 733       // 214.  set::find() missing const overload
 734       //@{
 735       /**
 736        *  @brief Tries to locate an element in a %set.
 737        *  @param  __x  Element to be located.
 738        *  @return  Iterator pointing to sought-after element, or end() if not
 739        *           found.
 740        *
 741        *  This function takes a key and tries to locate the element with which
 742        *  the key matches.  If successful the function returns an iterator
 743        *  pointing to the sought after element.  If unsuccessful it returns the
 744        *  past-the-end ( @c end() ) iterator.
 745        */
 746       iterator
 747       find(const key_type& __x)
 748       { return _M_t.find(__x); }
 749
 750       const_iterator
 751       find(const key_type& __x) const
 752       { return _M_t.find(__x); }
 753
 754 #if __cplusplus > 201103L
 755       template<typename _Kt>
 756         auto
 757         find(const _Kt& __x)
 758         -> decltype(iterator{_M_t._M_find_tr(__x)})
 759         { return iterator{_M_t._M_find_tr(__x)}; }
 760
 761       template<typename _Kt>
 762         auto
 763         find(const _Kt& __x) const
 764         -> decltype(const_iterator{_M_t._M_find_tr(__x)})
 765         { return const_iterator{_M_t._M_find_tr(__x)}; }
 766 #endif
 767       //@}
 768
 769       //@{
 770       /**
 771        *  @brief Finds the beginning of a subsequence matching given key.
 772        *  @param  __x  Key to be located.
 773        *  @return  Iterator pointing to first element equal to or greater
 774        *           than key, or end().
 775        *
 776        *  This function returns the first element of a subsequence of elements
 777        *  that matches the given key.  If unsuccessful it returns an iterator
 778        *  pointing to the first element that has a greater value than given key
 779        *  or end() if no such element exists.
 780        */
 781       iterator
 782       lower_bound(const key_type& __x)
 783       { return _M_t.lower_bound(__x); }
 784
 785       const_iterator
 786       lower_bound(const key_type& __x) const
 787       { return _M_t.lower_bound(__x); }
 788
 789 #if __cplusplus > 201103L
 790       template<typename _Kt>
 791         auto
 792         lower_bound(const _Kt& __x)
 793         -> decltype(iterator(_M_t._M_lower_bound_tr(__x)))
 794         { return iterator(_M_t._M_lower_bound_tr(__x)); }
 795
 796       template<typename _Kt>
 797         auto
 798         lower_bound(const _Kt& __x) const
 799         -> decltype(iterator(_M_t._M_lower_bound_tr(__x)))
 800         { return iterator(_M_t._M_lower_bound_tr(__x)); }
 801 #endif
 802       //@}
 803
 804       //@{
 805       /**
 806        *  @brief Finds the end of a subsequence matching given key.
 807        *  @param  __x  Key to be located.
 808        *  @return Iterator pointing to the first element
 809        *          greater than key, or end().
 810        */
 811       iterator
 812       upper_bound(const key_type& __x)
 813       { return _M_t.upper_bound(__x); }
 814
 815       const_iterator
 816       upper_bound(const key_type& __x) const
 817       { return _M_t.upper_bound(__x); }
 818
 819 #if __cplusplus > 201103L
 820       template<typename _Kt>
 821         auto
 822         upper_bound(const _Kt& __x)
 823         -> decltype(iterator(_M_t._M_upper_bound_tr(__x)))
 824         { return iterator(_M_t._M_upper_bound_tr(__x)); }
 825
 826       template<typename _Kt>
 827         auto
 828         upper_bound(const _Kt& __x) const
 829         -> decltype(iterator(_M_t._M_upper_bound_tr(__x)))
 830         { return iterator(_M_t._M_upper_bound_tr(__x)); }
 831 #endif
 832       //@}
 833
 834       //@{
 835       /**
 836        *  @brief Finds a subsequence matching given key.
 837        *  @param  __x  Key to be located.
 838        *  @return  Pair of iterators that possibly points to the subsequence
 839        *           matching given key.
 840        *
 841        *  This function is equivalent to
 842        *  @code
 843        *    std::make_pair(c.lower_bound(val),
 844        *                   c.upper_bound(val))
 845        *  @endcode
 846        *  (but is faster than making the calls separately).
 847        *
 848        *  This function probably only makes sense for multisets.
 849        */
 850       std::pair<iterator, iterator>
 851       equal_range(const key_type& __x)
 852       { return _M_t.equal_range(__x); }
 853
 854       std::pair<const_iterator, const_iterator>
 855       equal_range(const key_type& __x) const
 856       { return _M_t.equal_range(__x); }
 857
 858 #if __cplusplus > 201103L
 859       template<typename _Kt>
 860         auto
 861         equal_range(const _Kt& __x)
 862         -> decltype(pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)))
 863         { return pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)); }
 864
 865       template<typename _Kt>
 866         auto
 867         equal_range(const _Kt& __x) const
 868         -> decltype(pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)))
 869         { return pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)); }
 870 #endif
 871       //@}
 872
 873       template<typename _K1, typename _C1, typename _A1>
 874         friend bool
 875         operator==(const multiset<_K1, _C1, _A1>&,
 876                    const multiset<_K1, _C1, _A1>&);
 877
 878       template<typename _K1, typename _C1, typename _A1>
 879         friend bool
 880         operator< (const multiset<_K1, _C1, _A1>&,
 881                    const multiset<_K1, _C1, _A1>&);
 882     };
 883
 884   /**
 885    *  @brief  Multiset equality comparison.
 886    *  @param  __x  A %multiset.
 887    *  @param  __y  A %multiset of the same type as @a __x.
 888    *  @return  True iff the size and elements of the multisets are equal.
 889    *
 890    *  This is an equivalence relation.  It is linear in the size of the
 891    *  multisets.
 892    *  Multisets are considered equivalent if their sizes are equal, and if
 893    *  corresponding elements compare equal.
 894   */
 895   template<typename _Key, typename _Compare, typename _Alloc>
 896     inline bool
 897     operator==(const multiset<_Key, _Compare, _Alloc>& __x,
 898                const multiset<_Key, _Compare, _Alloc>& __y)
 899     { return __x._M_t == __y._M_t; }
 900
 901   /**
 902    *  @brief  Multiset ordering relation.
 903    *  @param  __x  A %multiset.
 904    *  @param  __y  A %multiset of the same type as @a __x.
 905    *  @return  True iff @a __x is lexicographically less than @a __y.
 906    *
 907    *  This is a total ordering relation.  It is linear in the size of the
 908    *  sets.  The elements must be comparable with @c <.
 909    *
 910    *  See std::lexicographical_compare() for how the determination is made.
 911   */
 912   template<typename _Key, typename _Compare, typename _Alloc>
 913     inline bool
 914     operator<(const multiset<_Key, _Compare, _Alloc>& __x,
 915               const multiset<_Key, _Compare, _Alloc>& __y)
 916     { return __x._M_t < __y._M_t; }
 917
 918   ///  Returns !(x == y).
 919   template<typename _Key, typename _Compare, typename _Alloc>
 920     inline bool
 921     operator!=(const multiset<_Key, _Compare, _Alloc>& __x,
 922                const multiset<_Key, _Compare, _Alloc>& __y)
 923     { return !(__x == __y); }
 924
 925   ///  Returns y < x.
 926   template<typename _Key, typename _Compare, typename _Alloc>
 927     inline bool
 928     operator>(const multiset<_Key,_Compare,_Alloc>& __x,
 929               const multiset<_Key,_Compare,_Alloc>& __y)
 930     { return __y < __x; }
 931
 932   ///  Returns !(y < x)
 933   template<typename _Key, typename _Compare, typename _Alloc>
 934     inline bool
 935     operator<=(const multiset<_Key, _Compare, _Alloc>& __x,
 936                const multiset<_Key, _Compare, _Alloc>& __y)
 937     { return !(__y < __x); }
 938
 939   ///  Returns !(x < y)
 940   template<typename _Key, typename _Compare, typename _Alloc>
 941     inline bool
 942     operator>=(const multiset<_Key, _Compare, _Alloc>& __x,
 943                const multiset<_Key, _Compare, _Alloc>& __y)
 944     { return !(__x < __y); }
 945
 946   /// See std::multiset::swap().
 947   template<typename _Key, typename _Compare, typename _Alloc>
 948     inline void
 949     swap(multiset<_Key, _Compare, _Alloc>& __x,
 950          multiset<_Key, _Compare, _Alloc>& __y)
 951     _GLIBCXX_NOEXCEPT_IF(noexcept(__x.swap(__y)))
 952     { __x.swap(__y); }
 953
 954 _GLIBCXX_END_NAMESPACE_CONTAINER
 955
 956 #if __cplusplus > 201402L
 957   // Allow std::multiset access to internals of compatible sets.
 958   template<typename _Val, typename _Cmp1, typename _Alloc, typename _Cmp2>
 959     struct
 960     _Rb_tree_merge_helper<_GLIBCXX_STD_C::multiset<_Val, _Cmp1, _Alloc>,
 961                           _Cmp2>
 962     {
 963     private:
 964       friend class _GLIBCXX_STD_C::multiset<_Val, _Cmp1, _Alloc>;
 965
 966       static auto&
 967       _S_get_tree(_GLIBCXX_STD_C::set<_Val, _Cmp2, _Alloc>& __set)
 968       { return __set._M_t; }
 969
 970       static auto&
 971       _S_get_tree(_GLIBCXX_STD_C::multiset<_Val, _Cmp2, _Alloc>& __set)
 972       { return __set._M_t; }
 973     };
 974 #endif // C++17
 975
 976 _GLIBCXX_END_NAMESPACE_VERSION
 977 } // namespace std
 978
 979 #endif /* _STL_MULTISET_H */