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      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       : _M_t(std::move(__x._M_t)) { }
    196 
    197       /**
    198        *  @brief  Builds a %multiset from an initializer_list.
    199        *  @param  l  An initializer_list.
    200        *  @param  comp  A comparison functor.
    201        *  @param  a  An allocator object.
    202        *
    203        *  Create a %multiset consisting of copies of the elements from
    204        *  the list.  This is linear in N if the list is already sorted,
    205        *  and NlogN otherwise (where N is @a l.size()).
    206        */
    207       multiset(initializer_list<value_type> __l,
    208 	       const _Compare& __comp = _Compare(),
    209 	       const allocator_type& __a = allocator_type())
    210       : _M_t(__comp, __a)
    211       { _M_t._M_insert_equal(__l.begin(), __l.end()); }
    212 #endif
    213 
    214       /**
    215        *  @brief  %Multiset assignment operator.
    216        *  @param  x  A %multiset of identical element and allocator types.
    217        *
    218        *  All the elements of @a x are copied, but unlike the copy constructor,
    219        *  the allocator object is not copied.
    220        */
    221       multiset&
    222       operator=(const multiset& __x)
    223       {
    224 	_M_t = __x._M_t;
    225 	return *this;
    226       }
    227 
    228 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    229       /**
    230        *  @brief  %Multiset move assignment operator.
    231        *  @param  x  A %multiset of identical element and allocator types.
    232        *
    233        *  The contents of @a x are moved into this %multiset (without copying).
    234        *  @a x is a valid, but unspecified %multiset.
    235        */
    236       multiset&
    237       operator=(multiset&& __x)
    238       {
    239 	// NB: DR 1204.
    240 	// NB: DR 675.
    241 	this->clear();
    242 	this->swap(__x);
    243 	return *this;
    244       }
    245 
    246       /**
    247        *  @brief  %Multiset list assignment operator.
    248        *  @param  l  An initializer_list.
    249        *
    250        *  This function fills a %multiset with copies of the elements in the
    251        *  initializer list @a l.
    252        *
    253        *  Note that the assignment completely changes the %multiset and
    254        *  that the resulting %multiset's size is the same as the number
    255        *  of elements assigned.  Old data may be lost.
    256        */
    257       multiset&
    258       operator=(initializer_list<value_type> __l)
    259       {
    260 	this->clear();
    261 	this->insert(__l.begin(), __l.end());
    262 	return *this;
    263       }
    264 #endif
    265 
    266       // accessors:
    267 
    268       ///  Returns the comparison object.
    269       key_compare
    270       key_comp() const
    271       { return _M_t.key_comp(); }
    272       ///  Returns the comparison object.
    273       value_compare
    274       value_comp() const
    275       { return _M_t.key_comp(); }
    276       ///  Returns the memory allocation object.
    277       allocator_type
    278       get_allocator() const
    279       { return _M_t.get_allocator(); }
    280 
    281       /**
    282        *  Returns a read-only (constant) iterator that points to the first
    283        *  element in the %multiset.  Iteration is done in ascending order
    284        *  according to the keys.
    285        */
    286       iterator
    287       begin() const
    288       { return _M_t.begin(); }
    289 
    290       /**
    291        *  Returns a read-only (constant) iterator that points one past the last
    292        *  element in the %multiset.  Iteration is done in ascending order
    293        *  according to the keys.
    294        */
    295       iterator
    296       end() const
    297       { return _M_t.end(); }
    298 
    299       /**
    300        *  Returns a read-only (constant) reverse iterator that points to the
    301        *  last element in the %multiset.  Iteration is done in descending order
    302        *  according to the keys.
    303        */
    304       reverse_iterator
    305       rbegin() const
    306       { return _M_t.rbegin(); }
    307 
    308       /**
    309        *  Returns a read-only (constant) reverse iterator that points to the
    310        *  last element in the %multiset.  Iteration is done in descending order
    311        *  according to the keys.
    312        */
    313       reverse_iterator
    314       rend() const
    315       { return _M_t.rend(); }
    316 
    317 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    318       /**
    319        *  Returns a read-only (constant) iterator that points to the first
    320        *  element in the %multiset.  Iteration is done in ascending order
    321        *  according to the keys.
    322        */
    323       iterator
    324       cbegin() const
    325       { return _M_t.begin(); }
    326 
    327       /**
    328        *  Returns a read-only (constant) iterator that points one past the last
    329        *  element in the %multiset.  Iteration is done in ascending order
    330        *  according to the keys.
    331        */
    332       iterator
    333       cend() const
    334       { return _M_t.end(); }
    335 
    336       /**
    337        *  Returns a read-only (constant) reverse iterator that points to the
    338        *  last element in the %multiset.  Iteration is done in descending order
    339        *  according to the keys.
    340        */
    341       reverse_iterator
    342       crbegin() const
    343       { return _M_t.rbegin(); }
    344 
    345       /**
    346        *  Returns a read-only (constant) reverse iterator that points to the
    347        *  last element in the %multiset.  Iteration is done in descending order
    348        *  according to the keys.
    349        */
    350       reverse_iterator
    351       crend() const
    352       { return _M_t.rend(); }
    353 #endif
    354 
    355       ///  Returns true if the %set is empty.
    356       bool
    357       empty() const
    358       { return _M_t.empty(); }
    359 
    360       ///  Returns the size of the %set.
    361       size_type
    362       size() const
    363       { return _M_t.size(); }
    364 
    365       ///  Returns the maximum size of the %set.
    366       size_type
    367       max_size() const
    368       { return _M_t.max_size(); }
    369 
    370       /**
    371        *  @brief  Swaps data with another %multiset.
    372        *  @param  x  A %multiset of the same element and allocator types.
    373        *
    374        *  This exchanges the elements between two multisets in constant time.
    375        *  (It is only swapping a pointer, an integer, and an instance of the @c
    376        *  Compare type (which itself is often stateless and empty), so it should
    377        *  be quite fast.)
    378        *  Note that the global std::swap() function is specialized such that
    379        *  std::swap(s1,s2) will feed to this function.
    380        */
    381       void
    382       swap(multiset& __x)
    383       { _M_t.swap(__x._M_t); }
    384 
    385       // insert/erase
    386       /**
    387        *  @brief Inserts an element into the %multiset.
    388        *  @param  x  Element to be inserted.
    389        *  @return An iterator that points to the inserted element.
    390        *
    391        *  This function inserts an element into the %multiset.  Contrary
    392        *  to a std::set the %multiset does not rely on unique keys and thus
    393        *  multiple copies of the same element can be inserted.
    394        *
    395        *  Insertion requires logarithmic time.
    396        */
    397       iterator
    398       insert(const value_type& __x)
    399       { return _M_t._M_insert_equal(__x); }
    400 
    401 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    402       iterator
    403       insert(value_type&& __x)
    404       { return _M_t._M_insert_equal(std::move(__x)); }
    405 #endif
    406 
    407       /**
    408        *  @brief Inserts an element into the %multiset.
    409        *  @param  position  An iterator that serves as a hint as to where the
    410        *                    element should be inserted.
    411        *  @param  x  Element to be inserted.
    412        *  @return An iterator that points to the inserted element.
    413        *
    414        *  This function inserts an element into the %multiset.  Contrary
    415        *  to a std::set the %multiset does not rely on unique keys and thus
    416        *  multiple copies of the same element can be inserted.
    417        *
    418        *  Note that the first parameter is only a hint and can potentially
    419        *  improve the performance of the insertion process.  A bad hint would
    420        *  cause no gains in efficiency.
    421        *
    422        *  See http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt07ch17.html
    423        *  for more on @a hinting.
    424        *
    425        *  Insertion requires logarithmic time (if the hint is not taken).
    426        */
    427       iterator
    428       insert(const_iterator __position, const value_type& __x)
    429       { return _M_t._M_insert_equal_(__position, __x); }
    430 
    431 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    432       iterator
    433       insert(const_iterator __position, value_type&& __x)
    434       { return _M_t._M_insert_equal_(__position, std::move(__x)); }
    435 #endif
    436 
    437       /**
    438        *  @brief A template function that tries to insert a range of elements.
    439        *  @param  first  Iterator pointing to the start of the range to be
    440        *                 inserted.
    441        *  @param  last  Iterator pointing to the end of the range.
    442        *
    443        *  Complexity similar to that of the range constructor.
    444        */
    445       template<typename _InputIterator>
    446         void
    447         insert(_InputIterator __first, _InputIterator __last)
    448         { _M_t._M_insert_equal(__first, __last); }
    449 
    450 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    451       /**
    452        *  @brief Attempts to insert a list of elements into the %multiset.
    453        *  @param  list  A std::initializer_list<value_type> of elements
    454        *                to be inserted.
    455        *
    456        *  Complexity similar to that of the range constructor.
    457        */
    458       void
    459       insert(initializer_list<value_type> __l)
    460       { this->insert(__l.begin(), __l.end()); }
    461 #endif
    462 
    463 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    464       // _GLIBCXX_RESOLVE_LIB_DEFECTS
    465       // DR 130. Associative erase should return an iterator.
    466       /**
    467        *  @brief Erases an element from a %multiset.
    468        *  @param  position  An iterator pointing to the element to be erased.
    469        *  @return An iterator pointing to the element immediately following
    470        *          @a position prior to the element being erased. If no such
    471        *          element exists, end() is returned.
    472        *
    473        *  This function erases an element, pointed to by the given iterator,
    474        *  from a %multiset.  Note that this function only erases the element,
    475        *  and that if the element is itself a pointer, the pointed-to memory is
    476        *  not touched in any way.  Managing the pointer is the user's
    477        *  responsibility.
    478        */
    479       iterator
    480       erase(const_iterator __position)
    481       { return _M_t.erase(__position); }
    482 #else
    483       /**
    484        *  @brief Erases an element from a %multiset.
    485        *  @param  position  An iterator pointing to the element to be erased.
    486        *
    487        *  This function erases an element, pointed to by the given iterator,
    488        *  from a %multiset.  Note that this function only erases the element,
    489        *  and that if the element is itself a pointer, the pointed-to memory is
    490        *  not touched in any way.  Managing the pointer is the user's
    491        *  responsibility.
    492        */
    493       void
    494       erase(iterator __position)
    495       { _M_t.erase(__position); }
    496 #endif
    497 
    498       /**
    499        *  @brief Erases elements according to the provided key.
    500        *  @param  x  Key of element to be erased.
    501        *  @return  The number of elements erased.
    502        *
    503        *  This function erases all elements located by the given key from a
    504        *  %multiset.
    505        *  Note that this function only erases the element, and that if
    506        *  the element is itself a pointer, the pointed-to memory is not touched
    507        *  in any way.  Managing the pointer is the user's responsibility.
    508        */
    509       size_type
    510       erase(const key_type& __x)
    511       { return _M_t.erase(__x); }
    512 
    513 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    514       // _GLIBCXX_RESOLVE_LIB_DEFECTS
    515       // DR 130. Associative erase should return an iterator.
    516       /**
    517        *  @brief Erases a [first,last) range of elements from a %multiset.
    518        *  @param  first  Iterator pointing to the start of the range to be
    519        *                 erased.
    520        *  @param  last  Iterator pointing to the end of the range to be erased.
    521        *  @return The iterator @a last.
    522        *
    523        *  This function erases a sequence of elements from a %multiset.
    524        *  Note that this function only erases the elements, and that if
    525        *  the elements themselves are pointers, the pointed-to memory is not
    526        *  touched in any way.  Managing the pointer is the user's
    527        *  responsibility.
    528        */
    529       iterator
    530       erase(const_iterator __first, const_iterator __last)
    531       { return _M_t.erase(__first, __last); }
    532 #else
    533       /**
    534        *  @brief Erases a [first,last) range of elements from a %multiset.
    535        *  @param  first  Iterator pointing to the start of the range to be
    536        *                 erased.
    537        *  @param  last  Iterator pointing to the end of the range to be erased.
    538        *
    539        *  This function erases a sequence of elements from a %multiset.
    540        *  Note that this function only erases the elements, and that if
    541        *  the elements themselves are pointers, the pointed-to memory is not
    542        *  touched in any way.  Managing the pointer is the user's
    543        *  responsibility.
    544        */
    545       void
    546       erase(iterator __first, iterator __last)
    547       { _M_t.erase(__first, __last); }
    548 #endif
    549 
    550       /**
    551        *  Erases all elements in a %multiset.  Note that this function only
    552        *  erases the elements, and that if the elements themselves are pointers,
    553        *  the pointed-to memory is not touched in any way.  Managing the pointer
    554        *  is the user's responsibility.
    555        */
    556       void
    557       clear()
    558       { _M_t.clear(); }
    559 
    560       // multiset operations:
    561 
    562       /**
    563        *  @brief Finds the number of elements with given key.
    564        *  @param  x  Key of elements to be located.
    565        *  @return Number of elements with specified key.
    566        */
    567       size_type
    568       count(const key_type& __x) const
    569       { return _M_t.count(__x); }
    570 
    571       // _GLIBCXX_RESOLVE_LIB_DEFECTS
    572       // 214.  set::find() missing const overload
    573       //@{
    574       /**
    575        *  @brief Tries to locate an element in a %set.
    576        *  @param  x  Element to be located.
    577        *  @return  Iterator pointing to sought-after element, or end() if not
    578        *           found.
    579        *
    580        *  This function takes a key and tries to locate the element with which
    581        *  the key matches.  If successful the function returns an iterator
    582        *  pointing to the sought after element.  If unsuccessful it returns the
    583        *  past-the-end ( @c end() ) iterator.
    584        */
    585       iterator
    586       find(const key_type& __x)
    587       { return _M_t.find(__x); }
    588 
    589       const_iterator
    590       find(const key_type& __x) const
    591       { return _M_t.find(__x); }
    592       //@}
    593 
    594       //@{
    595       /**
    596        *  @brief Finds the beginning of a subsequence matching given key.
    597        *  @param  x  Key to be located.
    598        *  @return  Iterator pointing to first element equal to or greater
    599        *           than key, or end().
    600        *
    601        *  This function returns the first element of a subsequence of elements
    602        *  that matches the given key.  If unsuccessful it returns an iterator
    603        *  pointing to the first element that has a greater value than given key
    604        *  or end() if no such element exists.
    605        */
    606       iterator
    607       lower_bound(const key_type& __x)
    608       { return _M_t.lower_bound(__x); }
    609 
    610       const_iterator
    611       lower_bound(const key_type& __x) const
    612       { return _M_t.lower_bound(__x); }
    613       //@}
    614 
    615       //@{
    616       /**
    617        *  @brief Finds the end of a subsequence matching given key.
    618        *  @param  x  Key to be located.
    619        *  @return Iterator pointing to the first element
    620        *          greater than key, or end().
    621        */
    622       iterator
    623       upper_bound(const key_type& __x)
    624       { return _M_t.upper_bound(__x); }
    625 
    626       const_iterator
    627       upper_bound(const key_type& __x) const
    628       { return _M_t.upper_bound(__x); }
    629       //@}
    630 
    631       //@{
    632       /**
    633        *  @brief Finds a subsequence matching given key.
    634        *  @param  x  Key to be located.
    635        *  @return  Pair of iterators that possibly points to the subsequence
    636        *           matching given key.
    637        *
    638        *  This function is equivalent to
    639        *  @code
    640        *    std::make_pair(c.lower_bound(val),
    641        *                   c.upper_bound(val))
    642        *  @endcode
    643        *  (but is faster than making the calls separately).
    644        *
    645        *  This function probably only makes sense for multisets.
    646        */
    647       std::pair<iterator, iterator>
    648       equal_range(const key_type& __x)
    649       { return _M_t.equal_range(__x); }
    650 
    651       std::pair<const_iterator, const_iterator>
    652       equal_range(const key_type& __x) const
    653       { return _M_t.equal_range(__x); }
    654 
    655       template<typename _K1, typename _C1, typename _A1>
    656         friend bool
    657         operator==(const multiset<_K1, _C1, _A1>&,
    658 		   const multiset<_K1, _C1, _A1>&);
    659 
    660       template<typename _K1, typename _C1, typename _A1>
    661         friend bool
    662         operator< (const multiset<_K1, _C1, _A1>&,
    663 		   const multiset<_K1, _C1, _A1>&);
    664     };
    665 
    666   /**
    667    *  @brief  Multiset equality comparison.
    668    *  @param  x  A %multiset.
    669    *  @param  y  A %multiset of the same type as @a x.
    670    *  @return  True iff the size and elements of the multisets are equal.
    671    *
    672    *  This is an equivalence relation.  It is linear in the size of the
    673    *  multisets.
    674    *  Multisets are considered equivalent if their sizes are equal, and if
    675    *  corresponding elements compare equal.
    676   */
    677   template<typename _Key, typename _Compare, typename _Alloc>
    678     inline bool
    679     operator==(const multiset<_Key, _Compare, _Alloc>& __x,
    680 	       const multiset<_Key, _Compare, _Alloc>& __y)
    681     { return __x._M_t == __y._M_t; }
    682 
    683   /**
    684    *  @brief  Multiset ordering relation.
    685    *  @param  x  A %multiset.
    686    *  @param  y  A %multiset of the same type as @a x.
    687    *  @return  True iff @a x is lexicographically less than @a y.
    688    *
    689    *  This is a total ordering relation.  It is linear in the size of the
    690    *  maps.  The elements must be comparable with @c <.
    691    *
    692    *  See std::lexicographical_compare() for how the determination is made.
    693   */
    694   template<typename _Key, typename _Compare, typename _Alloc>
    695     inline bool
    696     operator<(const multiset<_Key, _Compare, _Alloc>& __x,
    697 	      const multiset<_Key, _Compare, _Alloc>& __y)
    698     { return __x._M_t < __y._M_t; }
    699 
    700   ///  Returns !(x == y).
    701   template<typename _Key, typename _Compare, typename _Alloc>
    702     inline bool
    703     operator!=(const multiset<_Key, _Compare, _Alloc>& __x,
    704 	       const multiset<_Key, _Compare, _Alloc>& __y)
    705     { return !(__x == __y); }
    706 
    707   ///  Returns y < x.
    708   template<typename _Key, typename _Compare, typename _Alloc>
    709     inline bool
    710     operator>(const multiset<_Key,_Compare,_Alloc>& __x,
    711 	      const multiset<_Key,_Compare,_Alloc>& __y)
    712     { return __y < __x; }
    713 
    714   ///  Returns !(y < x)
    715   template<typename _Key, typename _Compare, typename _Alloc>
    716     inline bool
    717     operator<=(const multiset<_Key, _Compare, _Alloc>& __x,
    718 	       const multiset<_Key, _Compare, _Alloc>& __y)
    719     { return !(__y < __x); }
    720 
    721   ///  Returns !(x < y)
    722   template<typename _Key, typename _Compare, typename _Alloc>
    723     inline bool
    724     operator>=(const multiset<_Key, _Compare, _Alloc>& __x,
    725 	       const multiset<_Key, _Compare, _Alloc>& __y)
    726     { return !(__x < __y); }
    727 
    728   /// See std::multiset::swap().
    729   template<typename _Key, typename _Compare, typename _Alloc>
    730     inline void
    731     swap(multiset<_Key, _Compare, _Alloc>& __x,
    732 	 multiset<_Key, _Compare, _Alloc>& __y)
    733     { __x.swap(__y); }
    734 
    735 _GLIBCXX_END_NAMESPACE_CONTAINER
    736 } // namespace std
    737 
    738 #endif /* _STL_MULTISET_H */
    739