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      1 // Set 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) 1996,1997
     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_set.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_SET_H
     58 #define _STL_SET_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 unique keys, which can be
     69    *  retrieved 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 unique keys).
     76    *
     77    *  Sets support bidirectional iterators.
     78    *
     79    *  @param  Key  Type of key objects.
     80    *  @param  Compare  Comparison function object type, defaults to less<Key>.
     81    *  @param  Alloc  Allocator type, defaults to allocator<Key>.
     82    *
     83    *  The private tree data is declared exactly the same way for set and
     84    *  multiset; the distinction is made entirely in how the tree functions are
     85    *  called (*_unique versus *_equal, same as the standard).
     86   */
     87   template<typename _Key, typename _Compare = std::less<_Key>,
     88 	   typename _Alloc = std::allocator<_Key> >
     89     class set
     90     {
     91       // concept requirements
     92       typedef typename _Alloc::value_type                   _Alloc_value_type;
     93       __glibcxx_class_requires(_Key, _SGIAssignableConcept)
     94       __glibcxx_class_requires4(_Compare, bool, _Key, _Key,
     95 				_BinaryFunctionConcept)
     96       __glibcxx_class_requires2(_Key, _Alloc_value_type, _SameTypeConcept)
     97 
     98     public:
     99       // typedefs:
    100       //@{
    101       /// Public typedefs.
    102       typedef _Key     key_type;
    103       typedef _Key     value_type;
    104       typedef _Compare key_compare;
    105       typedef _Compare value_compare;
    106       typedef _Alloc   allocator_type;
    107       //@}
    108 
    109     private:
    110       typedef typename _Alloc::template rebind<_Key>::other _Key_alloc_type;
    111 
    112       typedef _Rb_tree<key_type, value_type, _Identity<value_type>,
    113 		       key_compare, _Key_alloc_type> _Rep_type;
    114       _Rep_type _M_t;  // Red-black tree representing set.
    115 
    116     public:
    117       //@{
    118       ///  Iterator-related typedefs.
    119       typedef typename _Key_alloc_type::pointer             pointer;
    120       typedef typename _Key_alloc_type::const_pointer       const_pointer;
    121       typedef typename _Key_alloc_type::reference           reference;
    122       typedef typename _Key_alloc_type::const_reference     const_reference;
    123       // _GLIBCXX_RESOLVE_LIB_DEFECTS
    124       // DR 103. set::iterator is required to be modifiable,
    125       // but this allows modification of keys.
    126       typedef typename _Rep_type::const_iterator            iterator;
    127       typedef typename _Rep_type::const_iterator            const_iterator;
    128       typedef typename _Rep_type::const_reverse_iterator    reverse_iterator;
    129       typedef typename _Rep_type::const_reverse_iterator const_reverse_iterator;
    130       typedef typename _Rep_type::size_type                 size_type;
    131       typedef typename _Rep_type::difference_type           difference_type;
    132       //@}
    133 
    134       // allocation/deallocation
    135       /**
    136        *  @brief  Default constructor creates no elements.
    137        */
    138       set()
    139       : _M_t() { }
    140 
    141       /**
    142        *  @brief  Creates a %set with no elements.
    143        *  @param  comp  Comparator to use.
    144        *  @param  a  An allocator object.
    145        */
    146       explicit
    147       set(const _Compare& __comp,
    148 	  const allocator_type& __a = allocator_type())
    149       : _M_t(__comp, __a) { }
    150 
    151       /**
    152        *  @brief  Builds a %set from a range.
    153        *  @param  first  An input iterator.
    154        *  @param  last  An input iterator.
    155        *
    156        *  Create a %set consisting of copies of the elements from [first,last).
    157        *  This is linear in N if the range is already sorted, and NlogN
    158        *  otherwise (where N is distance(first,last)).
    159        */
    160       template<typename _InputIterator>
    161 	set(_InputIterator __first, _InputIterator __last)
    162 	: _M_t()
    163 	{ _M_t._M_insert_unique(__first, __last); }
    164 
    165       /**
    166        *  @brief  Builds a %set from a range.
    167        *  @param  first  An input iterator.
    168        *  @param  last  An input iterator.
    169        *  @param  comp  A comparison functor.
    170        *  @param  a  An allocator object.
    171        *
    172        *  Create a %set consisting of copies of the elements from [first,last).
    173        *  This is linear in N if the range is already sorted, and NlogN
    174        *  otherwise (where N is distance(first,last)).
    175        */
    176       template<typename _InputIterator>
    177 	set(_InputIterator __first, _InputIterator __last,
    178 	    const _Compare& __comp,
    179 	    const allocator_type& __a = allocator_type())
    180 	: _M_t(__comp, __a)
    181 	{ _M_t._M_insert_unique(__first, __last); }
    182 
    183       /**
    184        *  @brief  %Set copy constructor.
    185        *  @param  x  A %set of identical element and allocator types.
    186        *
    187        *  The newly-created %set uses a copy of the allocation object used
    188        *  by @a x.
    189        */
    190       set(const set& __x)
    191       : _M_t(__x._M_t) { }
    192 
    193 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    194      /**
    195        *  @brief %Set move constructor
    196        *  @param x  A %set of identical element and allocator types.
    197        *
    198        *  The newly-created %set contains the exact contents of @a x.
    199        *  The contents of @a x are a valid, but unspecified %set.
    200        */
    201       set(set&& __x)
    202       : _M_t(std::move(__x._M_t)) { }
    203 
    204       /**
    205        *  @brief  Builds a %set from an initializer_list.
    206        *  @param  l  An initializer_list.
    207        *  @param  comp  A comparison functor.
    208        *  @param  a  An allocator object.
    209        *
    210        *  Create a %set consisting of copies of the elements in the list.
    211        *  This is linear in N if the list is already sorted, and NlogN
    212        *  otherwise (where N is @a l.size()).
    213        */
    214       set(initializer_list<value_type> __l,
    215 	  const _Compare& __comp = _Compare(),
    216 	  const allocator_type& __a = allocator_type())
    217       : _M_t(__comp, __a)
    218       { _M_t._M_insert_unique(__l.begin(), __l.end()); }
    219 #endif
    220 
    221       /**
    222        *  @brief  %Set assignment operator.
    223        *  @param  x  A %set of identical element and allocator types.
    224        *
    225        *  All the elements of @a x are copied, but unlike the copy constructor,
    226        *  the allocator object is not copied.
    227        */
    228       set&
    229       operator=(const set& __x)
    230       {
    231 	_M_t = __x._M_t;
    232 	return *this;
    233       }
    234 
    235 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    236       /**
    237        *  @brief %Set move assignment operator.
    238        *  @param x  A %set of identical element and allocator types.
    239        *
    240        *  The contents of @a x are moved into this %set (without copying).
    241        *  @a x is a valid, but unspecified %set.
    242        */
    243       set&
    244       operator=(set&& __x)
    245       {
    246 	// NB: DR 1204.
    247 	// NB: DR 675.
    248 	this->clear();
    249 	this->swap(__x);
    250       	return *this;
    251       }
    252 
    253       /**
    254        *  @brief  %Set list assignment operator.
    255        *  @param  l  An initializer_list.
    256        *
    257        *  This function fills a %set with copies of the elements in the
    258        *  initializer list @a l.
    259        *
    260        *  Note that the assignment completely changes the %set and
    261        *  that the resulting %set's size is the same as the number
    262        *  of elements assigned.  Old data may be lost.
    263        */
    264       set&
    265       operator=(initializer_list<value_type> __l)
    266       {
    267 	this->clear();
    268 	this->insert(__l.begin(), __l.end());
    269 	return *this;
    270       }
    271 #endif
    272 
    273       // accessors:
    274 
    275       ///  Returns the comparison object with which the %set was constructed.
    276       key_compare
    277       key_comp() const
    278       { return _M_t.key_comp(); }
    279       ///  Returns the comparison object with which the %set was constructed.
    280       value_compare
    281       value_comp() const
    282       { return _M_t.key_comp(); }
    283       ///  Returns the allocator object with which the %set was constructed.
    284       allocator_type
    285       get_allocator() const
    286       { return _M_t.get_allocator(); }
    287 
    288       /**
    289        *  Returns a read-only (constant) iterator that points to the first
    290        *  element in the %set.  Iteration is done in ascending order according
    291        *  to the keys.
    292        */
    293       iterator
    294       begin() const
    295       { return _M_t.begin(); }
    296 
    297       /**
    298        *  Returns a read-only (constant) iterator that points one past the last
    299        *  element in the %set.  Iteration is done in ascending order according
    300        *  to the keys.
    301        */
    302       iterator
    303       end() const
    304       { return _M_t.end(); }
    305 
    306       /**
    307        *  Returns a read-only (constant) iterator that points to the last
    308        *  element in the %set.  Iteration is done in descending order according
    309        *  to the keys.
    310        */
    311       reverse_iterator
    312       rbegin() const
    313       { return _M_t.rbegin(); }
    314 
    315       /**
    316        *  Returns a read-only (constant) reverse iterator that points to the
    317        *  last pair in the %set.  Iteration is done in descending order
    318        *  according to the keys.
    319        */
    320       reverse_iterator
    321       rend() const
    322       { return _M_t.rend(); }
    323 
    324 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    325       /**
    326        *  Returns a read-only (constant) iterator that points to the first
    327        *  element in the %set.  Iteration is done in ascending order according
    328        *  to the keys.
    329        */
    330       iterator
    331       cbegin() const
    332       { return _M_t.begin(); }
    333 
    334       /**
    335        *  Returns a read-only (constant) iterator that points one past the last
    336        *  element in the %set.  Iteration is done in ascending order according
    337        *  to the keys.
    338        */
    339       iterator
    340       cend() const
    341       { return _M_t.end(); }
    342 
    343       /**
    344        *  Returns a read-only (constant) iterator that points to the last
    345        *  element in the %set.  Iteration is done in descending order according
    346        *  to the keys.
    347        */
    348       reverse_iterator
    349       crbegin() const
    350       { return _M_t.rbegin(); }
    351 
    352       /**
    353        *  Returns a read-only (constant) reverse iterator that points to the
    354        *  last pair in the %set.  Iteration is done in descending order
    355        *  according to the keys.
    356        */
    357       reverse_iterator
    358       crend() const
    359       { return _M_t.rend(); }
    360 #endif
    361 
    362       ///  Returns true if the %set is empty.
    363       bool
    364       empty() const
    365       { return _M_t.empty(); }
    366 
    367       ///  Returns the size of the %set.
    368       size_type
    369       size() const
    370       { return _M_t.size(); }
    371 
    372       ///  Returns the maximum size of the %set.
    373       size_type
    374       max_size() const
    375       { return _M_t.max_size(); }
    376 
    377       /**
    378        *  @brief  Swaps data with another %set.
    379        *  @param  x  A %set of the same element and allocator types.
    380        *
    381        *  This exchanges the elements between two sets in constant time.
    382        *  (It is only swapping a pointer, an integer, and an instance of
    383        *  the @c Compare type (which itself is often stateless and empty), so it
    384        *  should be quite fast.)
    385        *  Note that the global std::swap() function is specialized such that
    386        *  std::swap(s1,s2) will feed to this function.
    387        */
    388       void
    389       swap(set& __x)
    390       { _M_t.swap(__x._M_t); }
    391 
    392       // insert/erase
    393       /**
    394        *  @brief Attempts to insert an element into the %set.
    395        *  @param  x  Element to be inserted.
    396        *  @return  A pair, of which the first element is an iterator that points
    397        *           to the possibly inserted element, and the second is a bool
    398        *           that is true if the element was actually inserted.
    399        *
    400        *  This function attempts to insert an element into the %set.  A %set
    401        *  relies on unique keys and thus an element is only inserted if it is
    402        *  not already present in the %set.
    403        *
    404        *  Insertion requires logarithmic time.
    405        */
    406       std::pair<iterator, bool>
    407       insert(const value_type& __x)
    408       {
    409 	std::pair<typename _Rep_type::iterator, bool> __p =
    410 	  _M_t._M_insert_unique(__x);
    411 	return std::pair<iterator, bool>(__p.first, __p.second);
    412       }
    413 
    414 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    415       std::pair<iterator, bool>
    416       insert(value_type&& __x)
    417       {
    418 	std::pair<typename _Rep_type::iterator, bool> __p =
    419 	  _M_t._M_insert_unique(std::move(__x));
    420 	return std::pair<iterator, bool>(__p.first, __p.second);
    421       }
    422 #endif
    423 
    424       /**
    425        *  @brief Attempts to insert an element into the %set.
    426        *  @param  position  An iterator that serves as a hint as to where the
    427        *                    element should be inserted.
    428        *  @param  x  Element to be inserted.
    429        *  @return  An iterator that points to the element with key of @a x (may
    430        *           or may not be the element passed in).
    431        *
    432        *  This function is not concerned about whether the insertion took place,
    433        *  and thus does not return a boolean like the single-argument insert()
    434        *  does.  Note that the first parameter is only a hint and can
    435        *  potentially improve the performance of the insertion process.  A bad
    436        *  hint would cause no gains in efficiency.
    437        *
    438        *  For more on @a hinting, see:
    439        *  http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt07ch17.html
    440        *
    441        *  Insertion requires logarithmic time (if the hint is not taken).
    442        */
    443       iterator
    444       insert(const_iterator __position, const value_type& __x)
    445       { return _M_t._M_insert_unique_(__position, __x); }
    446 
    447 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    448       iterator
    449       insert(const_iterator __position, value_type&& __x)
    450       { return _M_t._M_insert_unique_(__position, std::move(__x)); }
    451 #endif
    452 
    453       /**
    454        *  @brief A template function that attempts to insert a range
    455        *  of elements.
    456        *  @param  first  Iterator pointing to the start of the range to be
    457        *                 inserted.
    458        *  @param  last  Iterator pointing to the end of the range.
    459        *
    460        *  Complexity similar to that of the range constructor.
    461        */
    462       template<typename _InputIterator>
    463 	void
    464 	insert(_InputIterator __first, _InputIterator __last)
    465 	{ _M_t._M_insert_unique(__first, __last); }
    466 
    467 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    468       /**
    469        *  @brief Attempts to insert a list of elements into the %set.
    470        *  @param  list  A std::initializer_list<value_type> of elements
    471        *                to be inserted.
    472        *
    473        *  Complexity similar to that of the range constructor.
    474        */
    475       void
    476       insert(initializer_list<value_type> __l)
    477       { this->insert(__l.begin(), __l.end()); }
    478 #endif
    479 
    480 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    481       // _GLIBCXX_RESOLVE_LIB_DEFECTS
    482       // DR 130. Associative erase should return an iterator.
    483       /**
    484        *  @brief Erases an element from a %set.
    485        *  @param  position  An iterator pointing to the element to be erased.
    486        *  @return An iterator pointing to the element immediately following
    487        *          @a position prior to the element being erased. If no such
    488        *          element exists, end() is returned.
    489        *
    490        *  This function erases an element, pointed to by the given iterator,
    491        *  from a %set.  Note that this function only erases the element, and
    492        *  that if the element is itself a pointer, the pointed-to memory is not
    493        *  touched in any way.  Managing the pointer is the user's
    494        *  responsibility.
    495        */
    496       iterator
    497       erase(const_iterator __position)
    498       { return _M_t.erase(__position); }
    499 #else
    500       /**
    501        *  @brief Erases an element from a %set.
    502        *  @param  position  An iterator pointing to the element to be erased.
    503        *
    504        *  This function erases an element, pointed to by the given iterator,
    505        *  from a %set.  Note that this function only erases the element, and
    506        *  that if the element is itself a pointer, the pointed-to memory is not
    507        *  touched in any way.  Managing the pointer is the user's
    508        *  responsibility.
    509        */
    510       void
    511       erase(iterator __position)
    512       { _M_t.erase(__position); }
    513 #endif
    514 
    515       /**
    516        *  @brief Erases elements according to the provided key.
    517        *  @param  x  Key of element to be erased.
    518        *  @return  The number of elements erased.
    519        *
    520        *  This function erases all the elements located by the given key from
    521        *  a %set.
    522        *  Note that this function only erases the element, and that if
    523        *  the element is itself a pointer, the pointed-to memory is not touched
    524        *  in any way.  Managing the pointer is the user's responsibility.
    525        */
    526       size_type
    527       erase(const key_type& __x)
    528       { return _M_t.erase(__x); }
    529 
    530 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    531       // _GLIBCXX_RESOLVE_LIB_DEFECTS
    532       // DR 130. Associative erase should return an iterator.
    533       /**
    534        *  @brief Erases a [first,last) range of elements from a %set.
    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        *  @return The iterator @a last.
    539        *
    540        *  This function erases a sequence of elements from a %set.
    541        *  Note that this function only erases the element, and that if
    542        *  the element is itself a pointer, the pointed-to memory is not touched
    543        *  in any way.  Managing the pointer is the user's responsibility.
    544        */
    545       iterator
    546       erase(const_iterator __first, const_iterator __last)
    547       { return _M_t.erase(__first, __last); }
    548 #else
    549       /**
    550        *  @brief Erases a [first,last) range of elements from a %set.
    551        *  @param  first  Iterator pointing to the start of the range to be
    552        *                 erased.
    553        *  @param  last  Iterator pointing to the end of the range to be erased.
    554        *
    555        *  This function erases a sequence of elements from a %set.
    556        *  Note that this function only erases the element, and that if
    557        *  the element is itself a pointer, the pointed-to memory is not touched
    558        *  in any way.  Managing the pointer is the user's responsibility.
    559        */
    560       void
    561       erase(iterator __first, iterator __last)
    562       { _M_t.erase(__first, __last); }
    563 #endif
    564 
    565       /**
    566        *  Erases all elements in a %set.  Note that this function only erases
    567        *  the elements, and that if the elements themselves are pointers, the
    568        *  pointed-to memory is not touched in any way.  Managing the pointer is
    569        *  the user's responsibility.
    570        */
    571       void
    572       clear()
    573       { _M_t.clear(); }
    574 
    575       // set operations:
    576 
    577       /**
    578        *  @brief  Finds the number of elements.
    579        *  @param  x  Element to located.
    580        *  @return  Number of elements with specified key.
    581        *
    582        *  This function only makes sense for multisets; for set the result will
    583        *  either be 0 (not present) or 1 (present).
    584        */
    585       size_type
    586       count(const key_type& __x) const
    587       { return _M_t.find(__x) == _M_t.end() ? 0 : 1; }
    588 
    589       // _GLIBCXX_RESOLVE_LIB_DEFECTS
    590       // 214.  set::find() missing const overload
    591       //@{
    592       /**
    593        *  @brief Tries to locate an element in a %set.
    594        *  @param  x  Element to be located.
    595        *  @return  Iterator pointing to sought-after element, or end() if not
    596        *           found.
    597        *
    598        *  This function takes a key and tries to locate the element with which
    599        *  the key matches.  If successful the function returns an iterator
    600        *  pointing to the sought after element.  If unsuccessful it returns the
    601        *  past-the-end ( @c end() ) iterator.
    602        */
    603       iterator
    604       find(const key_type& __x)
    605       { return _M_t.find(__x); }
    606 
    607       const_iterator
    608       find(const key_type& __x) const
    609       { return _M_t.find(__x); }
    610       //@}
    611 
    612       //@{
    613       /**
    614        *  @brief Finds the beginning of a subsequence matching given key.
    615        *  @param  x  Key to be located.
    616        *  @return  Iterator pointing to first element equal to or greater
    617        *           than key, or end().
    618        *
    619        *  This function returns the first element of a subsequence of elements
    620        *  that matches the given key.  If unsuccessful it returns an iterator
    621        *  pointing to the first element that has a greater value than given key
    622        *  or end() if no such element exists.
    623        */
    624       iterator
    625       lower_bound(const key_type& __x)
    626       { return _M_t.lower_bound(__x); }
    627 
    628       const_iterator
    629       lower_bound(const key_type& __x) const
    630       { return _M_t.lower_bound(__x); }
    631       //@}
    632 
    633       //@{
    634       /**
    635        *  @brief Finds the end of a subsequence matching given key.
    636        *  @param  x  Key to be located.
    637        *  @return Iterator pointing to the first element
    638        *          greater than key, or end().
    639        */
    640       iterator
    641       upper_bound(const key_type& __x)
    642       { return _M_t.upper_bound(__x); }
    643 
    644       const_iterator
    645       upper_bound(const key_type& __x) const
    646       { return _M_t.upper_bound(__x); }
    647       //@}
    648 
    649       //@{
    650       /**
    651        *  @brief Finds a subsequence matching given key.
    652        *  @param  x  Key to be located.
    653        *  @return  Pair of iterators that possibly points to the subsequence
    654        *           matching given key.
    655        *
    656        *  This function is equivalent to
    657        *  @code
    658        *    std::make_pair(c.lower_bound(val),
    659        *                   c.upper_bound(val))
    660        *  @endcode
    661        *  (but is faster than making the calls separately).
    662        *
    663        *  This function probably only makes sense for multisets.
    664        */
    665       std::pair<iterator, iterator>
    666       equal_range(const key_type& __x)
    667       { return _M_t.equal_range(__x); }
    668 
    669       std::pair<const_iterator, const_iterator>
    670       equal_range(const key_type& __x) const
    671       { return _M_t.equal_range(__x); }
    672       //@}
    673 
    674       template<typename _K1, typename _C1, typename _A1>
    675 	friend bool
    676 	operator==(const set<_K1, _C1, _A1>&, const set<_K1, _C1, _A1>&);
    677 
    678       template<typename _K1, typename _C1, typename _A1>
    679 	friend bool
    680 	operator<(const set<_K1, _C1, _A1>&, const set<_K1, _C1, _A1>&);
    681     };
    682 
    683 
    684   /**
    685    *  @brief  Set equality comparison.
    686    *  @param  x  A %set.
    687    *  @param  y  A %set of the same type as @a x.
    688    *  @return  True iff the size and elements of the sets are equal.
    689    *
    690    *  This is an equivalence relation.  It is linear in the size of the sets.
    691    *  Sets are considered equivalent if their sizes are equal, and if
    692    *  corresponding elements compare equal.
    693   */
    694   template<typename _Key, typename _Compare, typename _Alloc>
    695     inline bool
    696     operator==(const set<_Key, _Compare, _Alloc>& __x,
    697 	       const set<_Key, _Compare, _Alloc>& __y)
    698     { return __x._M_t == __y._M_t; }
    699 
    700   /**
    701    *  @brief  Set ordering relation.
    702    *  @param  x  A %set.
    703    *  @param  y  A %set of the same type as @a x.
    704    *  @return  True iff @a x is lexicographically less than @a y.
    705    *
    706    *  This is a total ordering relation.  It is linear in the size of the
    707    *  maps.  The elements must be comparable with @c <.
    708    *
    709    *  See std::lexicographical_compare() for how the determination is made.
    710   */
    711   template<typename _Key, typename _Compare, typename _Alloc>
    712     inline bool
    713     operator<(const set<_Key, _Compare, _Alloc>& __x,
    714 	      const set<_Key, _Compare, _Alloc>& __y)
    715     { return __x._M_t < __y._M_t; }
    716 
    717   ///  Returns !(x == y).
    718   template<typename _Key, typename _Compare, typename _Alloc>
    719     inline bool
    720     operator!=(const set<_Key, _Compare, _Alloc>& __x,
    721 	       const set<_Key, _Compare, _Alloc>& __y)
    722     { return !(__x == __y); }
    723 
    724   ///  Returns y < x.
    725   template<typename _Key, typename _Compare, typename _Alloc>
    726     inline bool
    727     operator>(const set<_Key, _Compare, _Alloc>& __x,
    728 	      const set<_Key, _Compare, _Alloc>& __y)
    729     { return __y < __x; }
    730 
    731   ///  Returns !(y < x)
    732   template<typename _Key, typename _Compare, typename _Alloc>
    733     inline bool
    734     operator<=(const set<_Key, _Compare, _Alloc>& __x,
    735 	       const set<_Key, _Compare, _Alloc>& __y)
    736     { return !(__y < __x); }
    737 
    738   ///  Returns !(x < y)
    739   template<typename _Key, typename _Compare, typename _Alloc>
    740     inline bool
    741     operator>=(const set<_Key, _Compare, _Alloc>& __x,
    742 	       const set<_Key, _Compare, _Alloc>& __y)
    743     { return !(__x < __y); }
    744 
    745   /// See std::set::swap().
    746   template<typename _Key, typename _Compare, typename _Alloc>
    747     inline void
    748     swap(set<_Key, _Compare, _Alloc>& __x, set<_Key, _Compare, _Alloc>& __y)
    749     { __x.swap(__y); }
    750 
    751 _GLIBCXX_END_NAMESPACE_CONTAINER
    752 } //namespace std
    753 #endif /* _STL_SET_H */
    754