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

   1 // Multiset implementation -*- C++ -*-
   2
   3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
   4 // 2011 Free Software Foundation, Inc.
   5 //
   6 // This file is part of the GNU ISO C++ Library.  This library is free
   7 // software; you can redistribute it and/or modify it under the
   8 // terms of the GNU General Public License as published by the
   9 // Free Software Foundation; either version 3, or (at your option)
  10 // any later version.
  11
  12 // This library is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16
  17 // Under Section 7 of GPL version 3, you are granted additional
  18 // permissions described in the GCC Runtime Library Exception, version
  19 // 3.1, as published by the Free Software Foundation.
  20
  21 // You should have received a copy of the GNU General Public License and
  22 // a copy of the GCC Runtime Library Exception along with this program;
  23 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 // <http://www.gnu.org/licenses/>.
  25
  26 /*
  27  *
  28  * Copyright (c) 1994
  29  * Hewlett-Packard Company
  30  *
  31  * Permission to use, copy, modify, distribute and sell this software
  32  * and its documentation for any purpose is hereby granted without fee,
  33  * provided that the above copyright notice appear in all copies and
  34  * that both that copyright notice and this permission notice appear
  35  * in supporting documentation.  Hewlett-Packard Company makes no
  36  * representations about the suitability of this software for any
  37  * purpose.  It is provided "as is" without express or implied warranty.
  38  *
  39  *
  40  * Copyright (c) 1996
  41  * Silicon Graphics Computer Systems, Inc.
  42  *
  43  * Permission to use, copy, modify, distribute and sell this software
  44  * and its documentation for any purpose is hereby granted without fee,
  45  * provided that the above copyright notice appear in all copies and
  46  * that both that copyright notice and this permission notice appear
  47  * in supporting documentation.  Silicon Graphics makes no
  48  * representations about the suitability of this software for any
  49  * purpose.  It is provided "as is" without express or implied warranty.
  50  */
  51
  52 /** @file bits/stl_multiset.h
  53  *  This is an internal header file, included by other library headers.
  54  *  Do not attempt to use it directly. @headername{set}
  55  */
  56
  57 #ifndef _STL_MULTISET_H
  58 #define _STL_MULTISET_H 1
  59
  60 #include <bits/concept_check.h>
  61 #include <initializer_list>
  62
  63 namespace std _GLIBCXX_VISIBILITY(default)
  64 {
  65 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
  66
  67   /**
  68    *  @brief A standard container made up of elements, which can be retrieved
  69    *  in logarithmic time.
  70    *
  71    *  @ingroup associative_containers
  72    *
  73    *  Meets the requirements of a <a href="tables.html#65">container</a>, a
  74    *  <a href="tables.html#66">reversible container</a>, and an
  75    *  <a href="tables.html#69">associative container</a> (using equivalent
  76    *  keys).  For a @c multiset<Key> the key_type and value_type are Key.
  77    *
  78    *  Multisets support bidirectional iterators.
  79    *
  80    *  The private tree data is declared exactly the same way for set and
  81    *  multiset; the distinction is made entirely in how the tree functions are
  82    *  called (*_unique versus *_equal, same as the standard).
  83   */
  84   template <typename _Key, typename _Compare = std::less<_Key>,
  85             typename _Alloc = std::allocator<_Key> >
  86     class multiset
  87     {
  88       // concept requirements
  89       typedef typename _Alloc::value_type                   _Alloc_value_type;
  90       __glibcxx_class_requires(_Key, _SGIAssignableConcept)
  91       __glibcxx_class_requires4(_Compare, bool, _Key, _Key,
  92                                 _BinaryFunctionConcept)
  93       __glibcxx_class_requires2(_Key, _Alloc_value_type, _SameTypeConcept)
  94
  95     public:
  96       // typedefs:
  97       typedef _Key     key_type;
  98       typedef _Key     value_type;
  99       typedef _Compare key_compare;
 100       typedef _Compare value_compare;
 101       typedef _Alloc   allocator_type;
 102
 103     private:
 104       /// This turns a red-black tree into a [multi]set.
 105       typedef typename _Alloc::template rebind<_Key>::other _Key_alloc_type;
 106
 107       typedef _Rb_tree<key_type, value_type, _Identity<value_type>,
 108                        key_compare, _Key_alloc_type> _Rep_type;
 109       /// The actual tree structure.
 110       _Rep_type _M_t;
 111
 112     public:
 113       typedef typename _Key_alloc_type::pointer             pointer;
 114       typedef typename _Key_alloc_type::const_pointer       const_pointer;
 115       typedef typename _Key_alloc_type::reference           reference;
 116       typedef typename _Key_alloc_type::const_reference     const_reference;
 117       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 118       // DR 103. set::iterator is required to be modifiable,
 119       // but this allows modification of keys.
 120       typedef typename _Rep_type::const_iterator            iterator;
 121       typedef typename _Rep_type::const_iterator            const_iterator;
 122       typedef typename _Rep_type::const_reverse_iterator    reverse_iterator;
 123       typedef typename _Rep_type::const_reverse_iterator const_reverse_iterator;
 124       typedef typename _Rep_type::size_type                 size_type;
 125       typedef typename _Rep_type::difference_type           difference_type;
 126
 127       // allocation/deallocation
 128       /**
 129        *  @brief  Default constructor creates no elements.
 130        */
 131       multiset()
 132       : _M_t() { }
 133
 134       /**
 135        *  @brief  Creates a %multiset with no elements.
 136        *  @param  __comp  Comparator to use.
 137        *  @param  __a  An allocator object.
 138        */
 139       explicit
 140       multiset(const _Compare& __comp,
 141                const allocator_type& __a = allocator_type())
 142       : _M_t(__comp, __a) { }
 143
 144       /**
 145        *  @brief  Builds a %multiset from a range.
 146        *  @param  __first  An input iterator.
 147        *  @param  __last  An input iterator.
 148        *
 149        *  Create a %multiset consisting of copies of the elements from
 150        *  [first,last).  This is linear in N if the range is already sorted,
 151        *  and NlogN otherwise (where N is distance(__first,__last)).
 152        */
 153       template<typename _InputIterator>
 154         multiset(_InputIterator __first, _InputIterator __last)
 155         : _M_t()
 156         { _M_t._M_insert_equal(__first, __last); }
 157
 158       /**
 159        *  @brief  Builds a %multiset from a range.
 160        *  @param  __first  An input iterator.
 161        *  @param  __last  An input iterator.
 162        *  @param  __comp  A comparison functor.
 163        *  @param  __a  An allocator object.
 164        *
 165        *  Create a %multiset consisting of copies of the elements from
 166        *  [__first,__last).  This is linear in N if the range is already sorted,
 167        *  and NlogN otherwise (where N is distance(__first,__last)).
 168        */
 169       template<typename _InputIterator>
 170         multiset(_InputIterator __first, _InputIterator __last,
 171                  const _Compare& __comp,
 172                  const allocator_type& __a = allocator_type())
 173         : _M_t(__comp, __a)
 174         { _M_t._M_insert_equal(__first, __last); }
 175
 176       /**
 177        *  @brief  %Multiset copy constructor.
 178        *  @param  __x  A %multiset of identical element and allocator types.
 179        *
 180        *  The newly-created %multiset uses a copy of the allocation object used
 181        *  by @a __x.
 182        */
 183       multiset(const multiset& __x)
 184       : _M_t(__x._M_t) { }
 185
 186 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 187      /**
 188        *  @brief  %Multiset move constructor.
 189        *  @param  __x  A %multiset of identical element and allocator types.
 190        *
 191        *  The newly-created %multiset contains the exact contents of @a __x.
 192        *  The contents of @a __x are a valid, but unspecified %multiset.
 193        */
 194       multiset(multiset&& __x)
 195       noexcept(is_nothrow_copy_constructible<_Compare>::value)
 196       : _M_t(std::move(__x._M_t)) { }
 197
 198       /**
 199        *  @brief  Builds a %multiset from an initializer_list.
 200        *  @param  __l  An initializer_list.
 201        *  @param  __comp  A comparison functor.
 202        *  @param  __a  An allocator object.
 203        *
 204        *  Create a %multiset consisting of copies of the elements from
 205        *  the list.  This is linear in N if the list is already sorted,
 206        *  and NlogN otherwise (where N is @a __l.size()).
 207        */
 208       multiset(initializer_list<value_type> __l,
 209                const _Compare& __comp = _Compare(),
 210                const allocator_type& __a = allocator_type())
 211       : _M_t(__comp, __a)
 212       { _M_t._M_insert_equal(__l.begin(), __l.end()); }
 213 #endif
 214
 215       /**
 216        *  @brief  %Multiset assignment operator.
 217        *  @param  __x  A %multiset of identical element and allocator types.
 218        *
 219        *  All the elements of @a __x are copied, but unlike the copy
 220        *  constructor, the allocator object is not copied.
 221        */
 222       multiset&
 223       operator=(const multiset& __x)
 224       {
 225         _M_t = __x._M_t;
 226         return *this;
 227       }
 228
 229 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 230       /**
 231        *  @brief  %Multiset move assignment operator.
 232        *  @param  __x  A %multiset of identical element and allocator types.
 233        *
 234        *  The contents of @a __x are moved into this %multiset
 235        *  (without copying).  @a __x is a valid, but unspecified
 236        *  %multiset.
 237        */
 238       multiset&
 239       operator=(multiset&& __x)
 240       {
 241         // NB: DR 1204.
 242         // NB: DR 675.
 243         this->clear();
 244         this->swap(__x);
 245         return *this;
 246       }
 247
 248       /**
 249        *  @brief  %Multiset list assignment operator.
 250        *  @param  __l  An initializer_list.
 251        *
 252        *  This function fills a %multiset with copies of the elements in the
 253        *  initializer list @a __l.
 254        *
 255        *  Note that the assignment completely changes the %multiset and
 256        *  that the resulting %multiset's size is the same as the number
 257        *  of elements assigned.  Old data may be lost.
 258        */
 259       multiset&
 260       operator=(initializer_list<value_type> __l)
 261       {
 262         this->clear();
 263         this->insert(__l.begin(), __l.end());
 264         return *this;
 265       }
 266 #endif
 267
 268       // accessors:
 269
 270       ///  Returns the comparison object.
 271       key_compare
 272       key_comp() const
 273       { return _M_t.key_comp(); }
 274       ///  Returns the comparison object.
 275       value_compare
 276       value_comp() const
 277       { return _M_t.key_comp(); }
 278       ///  Returns the memory allocation object.
 279       allocator_type
 280       get_allocator() const _GLIBCXX_NOEXCEPT
 281       { return _M_t.get_allocator(); }
 282
 283       /**
 284        *  Returns a read-only (constant) iterator that points to the first
 285        *  element in the %multiset.  Iteration is done in ascending order
 286        *  according to the keys.
 287        */
 288       iterator
 289       begin() const _GLIBCXX_NOEXCEPT
 290       { return _M_t.begin(); }
 291
 292       /**
 293        *  Returns a read-only (constant) iterator that points one past the last
 294        *  element in the %multiset.  Iteration is done in ascending order
 295        *  according to the keys.
 296        */
 297       iterator
 298       end() const _GLIBCXX_NOEXCEPT
 299       { return _M_t.end(); }
 300
 301       /**
 302        *  Returns a read-only (constant) reverse iterator that points to the
 303        *  last element in the %multiset.  Iteration is done in descending order
 304        *  according to the keys.
 305        */
 306       reverse_iterator
 307       rbegin() const _GLIBCXX_NOEXCEPT
 308       { return _M_t.rbegin(); }
 309
 310       /**
 311        *  Returns a read-only (constant) reverse iterator that points to the
 312        *  last element in the %multiset.  Iteration is done in descending order
 313        *  according to the keys.
 314        */
 315       reverse_iterator
 316       rend() const _GLIBCXX_NOEXCEPT
 317       { return _M_t.rend(); }
 318
 319 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 320       /**
 321        *  Returns a read-only (constant) iterator that points to the first
 322        *  element in the %multiset.  Iteration is done in ascending order
 323        *  according to the keys.
 324        */
 325       iterator
 326       cbegin() const noexcept
 327       { return _M_t.begin(); }
 328
 329       /**
 330        *  Returns a read-only (constant) iterator that points one past the last
 331        *  element in the %multiset.  Iteration is done in ascending order
 332        *  according to the keys.
 333        */
 334       iterator
 335       cend() const noexcept
 336       { return _M_t.end(); }
 337
 338       /**
 339        *  Returns a read-only (constant) reverse iterator that points to the
 340        *  last element in the %multiset.  Iteration is done in descending order
 341        *  according to the keys.
 342        */
 343       reverse_iterator
 344       crbegin() const noexcept
 345       { return _M_t.rbegin(); }
 346
 347       /**
 348        *  Returns a read-only (constant) reverse iterator that points to the
 349        *  last element in the %multiset.  Iteration is done in descending order
 350        *  according to the keys.
 351        */
 352       reverse_iterator
 353       crend() const noexcept
 354       { return _M_t.rend(); }
 355 #endif
 356
 357       ///  Returns true if the %set is empty.
 358       bool
 359       empty() const _GLIBCXX_NOEXCEPT
 360       { return _M_t.empty(); }
 361
 362       ///  Returns the size of the %set.
 363       size_type
 364       size() const _GLIBCXX_NOEXCEPT
 365       { return _M_t.size(); }
 366
 367       ///  Returns the maximum size of the %set.
 368       size_type
 369       max_size() const _GLIBCXX_NOEXCEPT
 370       { return _M_t.max_size(); }
 371
 372       /**
 373        *  @brief  Swaps data with another %multiset.
 374        *  @param  __x  A %multiset of the same element and allocator types.
 375        *
 376        *  This exchanges the elements between two multisets in constant time.
 377        *  (It is only swapping a pointer, an integer, and an instance of the @c
 378        *  Compare type (which itself is often stateless and empty), so it should
 379        *  be quite fast.)
 380        *  Note that the global std::swap() function is specialized such that
 381        *  std::swap(s1,s2) will feed to this function.
 382        */
 383       void
 384       swap(multiset& __x)
 385       { _M_t.swap(__x._M_t); }
 386
 387       // insert/erase
 388       /**
 389        *  @brief Inserts an element into the %multiset.
 390        *  @param  __x  Element to be inserted.
 391        *  @return An iterator that points to the inserted element.
 392        *
 393        *  This function inserts an element into the %multiset.  Contrary
 394        *  to a std::set the %multiset does not rely on unique keys and thus
 395        *  multiple copies of the same element can be inserted.
 396        *
 397        *  Insertion requires logarithmic time.
 398        */
 399       iterator
 400       insert(const value_type& __x)
 401       { return _M_t._M_insert_equal(__x); }
 402
 403 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 404       iterator
 405       insert(value_type&& __x)
 406       { return _M_t._M_insert_equal(std::move(__x)); }
 407 #endif
 408
 409       /**
 410        *  @brief Inserts an element into the %multiset.
 411        *  @param  __position  An iterator that serves as a hint as to where the
 412        *                    element should be inserted.
 413        *  @param  __x  Element to be inserted.
 414        *  @return An iterator that points to the inserted element.
 415        *
 416        *  This function inserts an element into the %multiset.  Contrary
 417        *  to a std::set the %multiset does not rely on unique keys and thus
 418        *  multiple copies of the same element can be inserted.
 419        *
 420        *  Note that the first parameter is only a hint and can potentially
 421        *  improve the performance of the insertion process.  A bad hint would
 422        *  cause no gains in efficiency.
 423        *
 424        *  See http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt07ch17.html
 425        *  for more on @a hinting.
 426        *
 427        *  Insertion requires logarithmic time (if the hint is not taken).
 428        */
 429       iterator
 430       insert(const_iterator __position, const value_type& __x)
 431       { return _M_t._M_insert_equal_(__position, __x); }
 432
 433 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 434       iterator
 435       insert(const_iterator __position, value_type&& __x)
 436       { return _M_t._M_insert_equal_(__position, std::move(__x)); }
 437 #endif
 438
 439       /**
 440        *  @brief A template function that tries to insert a range of elements.
 441        *  @param  __first  Iterator pointing to the start of the range to be
 442        *                   inserted.
 443        *  @param  __last  Iterator pointing to the end of the range.
 444        *
 445        *  Complexity similar to that of the range constructor.
 446        */
 447       template<typename _InputIterator>
 448         void
 449         insert(_InputIterator __first, _InputIterator __last)
 450         { _M_t._M_insert_equal(__first, __last); }
 451
 452 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 453       /**
 454        *  @brief Attempts to insert a list of elements into the %multiset.
 455        *  @param  __l  A std::initializer_list<value_type> of elements
 456        *               to be inserted.
 457        *
 458        *  Complexity similar to that of the range constructor.
 459        */
 460       void
 461       insert(initializer_list<value_type> __l)
 462       { this->insert(__l.begin(), __l.end()); }
 463 #endif
 464
 465 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 466       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 467       // DR 130. Associative erase should return an iterator.
 468       /**
 469        *  @brief Erases an element from a %multiset.
 470        *  @param  __position  An iterator pointing to the element to be erased.
 471        *  @return An iterator pointing to the element immediately following
 472        *          @a position prior to the element being erased. If no such
 473        *          element exists, end() is returned.
 474        *
 475        *  This function erases an element, pointed to by the given iterator,
 476        *  from a %multiset.  Note that this function only erases the element,
 477        *  and that if the element is itself a pointer, the pointed-to memory is
 478        *  not touched in any way.  Managing the pointer is the user's
 479        *  responsibility.
 480        */
 481       iterator
 482       erase(const_iterator __position)
 483       { return _M_t.erase(__position); }
 484 #else
 485       /**
 486        *  @brief Erases an element from a %multiset.
 487        *  @param  __position  An iterator pointing to the element to be erased.
 488        *
 489        *  This function erases an element, pointed to by the given iterator,
 490        *  from a %multiset.  Note that this function only erases the element,
 491        *  and that if the element is itself a pointer, the pointed-to memory is
 492        *  not touched in any way.  Managing the pointer is the user's
 493        *  responsibility.
 494        */
 495       void
 496       erase(iterator __position)
 497       { _M_t.erase(__position); }
 498 #endif
 499
 500       /**
 501        *  @brief Erases elements according to the provided key.
 502        *  @param  __x  Key of element to be erased.
 503        *  @return  The number of elements erased.
 504        *
 505        *  This function erases all elements located by the given key from a
 506        *  %multiset.
 507        *  Note that this function only erases the element, and that if
 508        *  the element is itself a pointer, the pointed-to memory is not touched
 509        *  in any way.  Managing the pointer is the user's responsibility.
 510        */
 511       size_type
 512       erase(const key_type& __x)
 513       { return _M_t.erase(__x); }
 514
 515 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 516       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 517       // DR 130. Associative erase should return an iterator.
 518       /**
 519        *  @brief Erases a [first,last) range of elements from a %multiset.
 520        *  @param  __first  Iterator pointing to the start of the range to be
 521        *                   erased.
 522        *  @param __last Iterator pointing to the end of the range to
 523        *                be erased.
 524        *  @return The iterator @a last.
 525        *
 526        *  This function erases a sequence of elements from a %multiset.
 527        *  Note that this function only erases the elements, and that if
 528        *  the elements themselves are pointers, the pointed-to memory is not
 529        *  touched in any way.  Managing the pointer is the user's
 530        *  responsibility.
 531        */
 532       iterator
 533       erase(const_iterator __first, const_iterator __last)
 534       { return _M_t.erase(__first, __last); }
 535 #else
 536       /**
 537        *  @brief Erases a [first,last) range of elements from a %multiset.
 538        *  @param  first  Iterator pointing to the start of the range to be
 539        *                 erased.
 540        *  @param  last  Iterator pointing to the end of the range to be erased.
 541        *
 542        *  This function erases a sequence of elements from a %multiset.
 543        *  Note that this function only erases the elements, and that if
 544        *  the elements themselves are pointers, the pointed-to memory is not
 545        *  touched in any way.  Managing the pointer is the user's
 546        *  responsibility.
 547        */
 548       void
 549       erase(iterator __first, iterator __last)
 550       { _M_t.erase(__first, __last); }
 551 #endif
 552
 553       /**
 554        *  Erases all elements in a %multiset.  Note that this function only
 555        *  erases the elements, and that if the elements themselves are pointers,
 556        *  the pointed-to memory is not touched in any way.  Managing the pointer
 557        *  is the user's responsibility.
 558        */
 559       void
 560       clear() _GLIBCXX_NOEXCEPT
 561       { _M_t.clear(); }
 562
 563       // multiset operations:
 564
 565       /**
 566        *  @brief Finds the number of elements with given key.
 567        *  @param  __x  Key of elements to be located.
 568        *  @return Number of elements with specified key.
 569        */
 570       size_type
 571       count(const key_type& __x) const
 572       { return _M_t.count(__x); }
 573
 574       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 575       // 214.  set::find() missing const overload
 576       //@{
 577       /**
 578        *  @brief Tries to locate an element in a %set.
 579        *  @param  __x  Element to be located.
 580        *  @return  Iterator pointing to sought-after element, or end() if not
 581        *           found.
 582        *
 583        *  This function takes a key and tries to locate the element with which
 584        *  the key matches.  If successful the function returns an iterator
 585        *  pointing to the sought after element.  If unsuccessful it returns the
 586        *  past-the-end ( @c end() ) iterator.
 587        */
 588       iterator
 589       find(const key_type& __x)
 590       { return _M_t.find(__x); }
 591
 592       const_iterator
 593       find(const key_type& __x) const
 594       { return _M_t.find(__x); }
 595       //@}
 596
 597       //@{
 598       /**
 599        *  @brief Finds the beginning of a subsequence matching given key.
 600        *  @param  __x  Key to be located.
 601        *  @return  Iterator pointing to first element equal to or greater
 602        *           than key, or end().
 603        *
 604        *  This function returns the first element of a subsequence of elements
 605        *  that matches the given key.  If unsuccessful it returns an iterator
 606        *  pointing to the first element that has a greater value than given key
 607        *  or end() if no such element exists.
 608        */
 609       iterator
 610       lower_bound(const key_type& __x)
 611       { return _M_t.lower_bound(__x); }
 612
 613       const_iterator
 614       lower_bound(const key_type& __x) const
 615       { return _M_t.lower_bound(__x); }
 616       //@}
 617
 618       //@{
 619       /**
 620        *  @brief Finds the end of a subsequence matching given key.
 621        *  @param  __x  Key to be located.
 622        *  @return Iterator pointing to the first element
 623        *          greater than key, or end().
 624        */
 625       iterator
 626       upper_bound(const key_type& __x)
 627       { return _M_t.upper_bound(__x); }
 628
 629       const_iterator
 630       upper_bound(const key_type& __x) const
 631       { return _M_t.upper_bound(__x); }
 632       //@}
 633
 634       //@{
 635       /**
 636        *  @brief Finds a subsequence matching given key.
 637        *  @param  __x  Key to be located.
 638        *  @return  Pair of iterators that possibly points to the subsequence
 639        *           matching given key.
 640        *
 641        *  This function is equivalent to
 642        *  @code
 643        *    std::make_pair(c.lower_bound(val),
 644        *                   c.upper_bound(val))
 645        *  @endcode
 646        *  (but is faster than making the calls separately).
 647        *
 648        *  This function probably only makes sense for multisets.
 649        */
 650       std::pair<iterator, iterator>
 651       equal_range(const key_type& __x)
 652       { return _M_t.equal_range(__x); }
 653
 654       std::pair<const_iterator, const_iterator>
 655       equal_range(const key_type& __x) const
 656       { return _M_t.equal_range(__x); }
 657       //@}
 658
 659       template<typename _K1, typename _C1, typename _A1>
 660         friend bool
 661         operator==(const multiset<_K1, _C1, _A1>&,
 662                    const multiset<_K1, _C1, _A1>&);
 663
 664       template<typename _K1, typename _C1, typename _A1>
 665         friend bool
 666         operator< (const multiset<_K1, _C1, _A1>&,
 667                    const multiset<_K1, _C1, _A1>&);
 668     };
 669
 670   /**
 671    *  @brief  Multiset equality comparison.
 672    *  @param  __x  A %multiset.
 673    *  @param  __y  A %multiset of the same type as @a __x.
 674    *  @return  True iff the size and elements of the multisets are equal.
 675    *
 676    *  This is an equivalence relation.  It is linear in the size of the
 677    *  multisets.
 678    *  Multisets are considered equivalent if their sizes are equal, and if
 679    *  corresponding elements compare equal.
 680   */
 681   template<typename _Key, typename _Compare, typename _Alloc>
 682     inline bool
 683     operator==(const multiset<_Key, _Compare, _Alloc>& __x,
 684                const multiset<_Key, _Compare, _Alloc>& __y)
 685     { return __x._M_t == __y._M_t; }
 686
 687   /**
 688    *  @brief  Multiset ordering relation.
 689    *  @param  __x  A %multiset.
 690    *  @param  __y  A %multiset of the same type as @a __x.
 691    *  @return  True iff @a __x is lexicographically less than @a __y.
 692    *
 693    *  This is a total ordering relation.  It is linear in the size of the
 694    *  maps.  The elements must be comparable with @c <.
 695    *
 696    *  See std::lexicographical_compare() for how the determination is made.
 697   */
 698   template<typename _Key, typename _Compare, typename _Alloc>
 699     inline bool
 700     operator<(const multiset<_Key, _Compare, _Alloc>& __x,
 701               const multiset<_Key, _Compare, _Alloc>& __y)
 702     { return __x._M_t < __y._M_t; }
 703
 704   ///  Returns !(x == y).
 705   template<typename _Key, typename _Compare, typename _Alloc>
 706     inline bool
 707     operator!=(const multiset<_Key, _Compare, _Alloc>& __x,
 708                const multiset<_Key, _Compare, _Alloc>& __y)
 709     { return !(__x == __y); }
 710
 711   ///  Returns y < x.
 712   template<typename _Key, typename _Compare, typename _Alloc>
 713     inline bool
 714     operator>(const multiset<_Key,_Compare,_Alloc>& __x,
 715               const multiset<_Key,_Compare,_Alloc>& __y)
 716     { return __y < __x; }
 717
 718   ///  Returns !(y < x)
 719   template<typename _Key, typename _Compare, typename _Alloc>
 720     inline bool
 721     operator<=(const multiset<_Key, _Compare, _Alloc>& __x,
 722                const multiset<_Key, _Compare, _Alloc>& __y)
 723     { return !(__y < __x); }
 724
 725   ///  Returns !(x < y)
 726   template<typename _Key, typename _Compare, typename _Alloc>
 727     inline bool
 728     operator>=(const multiset<_Key, _Compare, _Alloc>& __x,
 729                const multiset<_Key, _Compare, _Alloc>& __y)
 730     { return !(__x < __y); }
 731
 732   /// See std::multiset::swap().
 733   template<typename _Key, typename _Compare, typename _Alloc>
 734     inline void
 735     swap(multiset<_Key, _Compare, _Alloc>& __x,
 736          multiset<_Key, _Compare, _Alloc>& __y)
 737     { __x.swap(__y); }
 738
 739 _GLIBCXX_END_NAMESPACE_CONTAINER
 740 } // namespace std
 741
 742 #endif /* _STL_MULTISET_H */