text: // Set implementation -*- C++ -*-
  
  // Copyright (C) 2001-2015 Free Software Foundation, Inc.
  //
  // This file is part of the GNU ISO C++ Library.  This library is free
  // software; you can redistribute it and/or modify it under the
  // terms of the GNU General Public License as published by the
  // Free Software Foundation; either version 3, or (at your option)
  // any later version.
  
  // This library is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  // GNU General Public License for more details.
  
  // Under Section 7 of GPL version 3, you are granted additional
  // permissions described in the GCC Runtime Library Exception, version
  // 3.1, as published by the Free Software Foundation.
  
  // You should have received a copy of the GNU General Public License and
  // a copy of the GCC Runtime Library Exception along with this program;
  // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  // <http://www.gnu.org/licenses/>.
  
  /*
   *
   * Copyright (c) 1994
   * Hewlett-Packard Company
   *
   * Permission to use, copy, modify, distribute and sell this software
   * and its documentation for any purpose is hereby granted without fee,
   * provided that the above copyright notice appear in all copies and
   * that both that copyright notice and this permission notice appear
   * in supporting documentation.  Hewlett-Packard Company makes no
   * representations about the suitability of this software for any
   * purpose.  It is provided "as is" without express or implied warranty.
   *
   *
   * Copyright (c) 1996,1997
   * Silicon Graphics Computer Systems, Inc.
   *
   * Permission to use, copy, modify, distribute and sell this software
   * and its documentation for any purpose is hereby granted without fee,
   * provided that the above copyright notice appear in all copies and
   * that both that copyright notice and this permission notice appear
   * in supporting documentation.  Silicon Graphics makes no
   * representations about the suitability of this software for any
   * purpose.  It is provided "as is" without express or implied warranty.
   */
  
  /** @file bits/stl_set.h
   *  This is an internal header file, included by other library headers.
   *  Do not attempt to use it directly. @headername{set}
   */
  
  #ifndef _STL_SET_H
  #define _STL_SET_H 1
  
  #include <bits/concept_check.h>
  #if __cplusplus >= 201103L
  #include <initializer_list>
  #endif
  
  namespace std _GLIBCXX_VISIBILITY(default)
  {
  _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
  
    /**
     *  @brief A standard container made up of unique keys, which can be
     *  retrieved in logarithmic time.
     *
     *  @ingroup associative_containers
     *
     *  @tparam _Key  Type of key objects.
     *  @tparam _Compare  Comparison function object type, defaults to less<_Key>.
     *  @tparam _Alloc  Allocator type, defaults to allocator<_Key>.
     *
     *  Meets the requirements of a <a href="tables.html#65">container</a>, a
     *  <a href="tables.html#66">reversible container</a>, and an
     *  <a href="tables.html#69">associative container</a> (using unique keys).
     *
     *  Sets support bidirectional iterators.
     *
     *  The private tree data is declared exactly the same way for set and
     *  multiset; the distinction is made entirely in how the tree functions are
     *  called (*_unique versus *_equal, same as the standard).
    */
    template<typename _Key, typename _Compare = std::less<_Key>,
  	   typename _Alloc = std::allocator<_Key> >
      class set
      {
        // concept requirements
        typedef typename _Alloc::value_type                   _Alloc_value_type;
        __glibcxx_class_requires(_Key, _SGIAssignableConcept)
        __glibcxx_class_requires4(_Compare, bool, _Key, _Key,
  				_BinaryFunctionConcept)
        __glibcxx_class_requires2(_Key, _Alloc_value_type, _SameTypeConcept)
  
      public:
        // typedefs:
        //@{
        /// Public typedefs.
        typedef _Key     key_type;
        typedef _Key     value_type;
        typedef _Compare key_compare;
        typedef _Compare value_compare;
        typedef _Alloc   allocator_type;
        //@}
  
      private:
        typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
  	rebind<_Key>::other _Key_alloc_type;
  
        typedef _Rb_tree<key_type, value_type, _Identity<value_type>,
  		       key_compare, _Key_alloc_type> _Rep_type;
        _Rep_type _M_t;  // Red-black tree representing set.
  
        typedef __gnu_cxx::__alloc_traits<_Key_alloc_type> _Alloc_traits;
  
      public:
        //@{
        ///  Iterator-related typedefs.
        typedef typename _Alloc_traits::pointer		    pointer;
        typedef typename _Alloc_traits::const_pointer	    const_pointer;
        typedef typename _Alloc_traits::reference		    reference;
        typedef typename _Alloc_traits::const_reference	    const_reference;
        // _GLIBCXX_RESOLVE_LIB_DEFECTS
        // DR 103. set::iterator is required to be modifiable,
        // but this allows modification of keys.
        typedef typename _Rep_type::const_iterator            iterator;
        typedef typename _Rep_type::const_iterator            const_iterator;
        typedef typename _Rep_type::const_reverse_iterator    reverse_iterator;
        typedef typename _Rep_type::const_reverse_iterator const_reverse_iterator;
        typedef typename _Rep_type::size_type                 size_type;
        typedef typename _Rep_type::difference_type           difference_type;
        //@}
  
        // allocation/deallocation
        /**
         *  @brief  Default constructor creates no elements.
         */
        set()
  #if __cplusplus >= 201103L
        noexcept(is_nothrow_default_constructible<allocator_type>::value)
  #endif
        : _M_t() { }
  
        /**
         *  @brief  Creates a %set with no elements.
         *  @param  __comp  Comparator to use.
         *  @param  __a  An allocator object.
         */
        explicit
        set(const _Compare& __comp,
  	  const allocator_type& __a = allocator_type())
        : _M_t(__comp, _Key_alloc_type(__a)) { }
  
        /**
         *  @brief  Builds a %set from a range.
         *  @param  __first  An input iterator.
         *  @param  __last  An input iterator.
         *
         *  Create a %set consisting of copies of the elements from
         *  [__first,__last).  This is linear in N if the range is
         *  already sorted, and NlogN otherwise (where N is
         *  distance(__first,__last)).
         */
        template<typename _InputIterator>
  	set(_InputIterator __first, _InputIterator __last)
  	: _M_t()
  	{ _M_t._M_insert_unique(__first, __last); }
  
        /**
         *  @brief  Builds a %set from a range.
         *  @param  __first  An input iterator.
         *  @param  __last  An input iterator.
         *  @param  __comp  A comparison functor.
         *  @param  __a  An allocator object.
         *
         *  Create a %set consisting of copies of the elements from
         *  [__first,__last).  This is linear in N if the range is
         *  already sorted, and NlogN otherwise (where N is
         *  distance(__first,__last)).
         */
        template<typename _InputIterator>
  	set(_InputIterator __first, _InputIterator __last,
  	    const _Compare& __comp,
  	    const allocator_type& __a = allocator_type())
  	: _M_t(__comp, _Key_alloc_type(__a))
          { _M_t._M_insert_unique(__first, __last); }
  
        /**
         *  @brief  %Set copy constructor.
         *  @param  __x  A %set of identical element and allocator types.
         *
         *  The newly-created %set uses a copy of the allocation object used
         *  by @a __x.
         */
        set(const set& __x)
        : _M_t(__x._M_t) { }
  
  #if __cplusplus >= 201103L
       /**
         *  @brief %Set move constructor
         *  @param __x  A %set of identical element and allocator types.
         *
         *  The newly-created %set contains the exact contents of @a x.
         *  The contents of @a x are a valid, but unspecified %set.
         */
        set(set&& __x)
        noexcept(is_nothrow_copy_constructible<_Compare>::value)
        : _M_t(std::move(__x._M_t)) { }
  
        /**
         *  @brief  Builds a %set from an initializer_list.
         *  @param  __l  An initializer_list.
         *  @param  __comp  A comparison functor.
         *  @param  __a  An allocator object.
         *
         *  Create a %set consisting of copies of the elements in the list.
         *  This is linear in N if the list is already sorted, and NlogN
         *  otherwise (where N is @a __l.size()).
         */
        set(initializer_list<value_type> __l,
  	  const _Compare& __comp = _Compare(),
  	  const allocator_type& __a = allocator_type())
        : _M_t(__comp, _Key_alloc_type(__a))
        { _M_t._M_insert_unique(__l.begin(), __l.end()); }
  
        /// Allocator-extended default constructor.
        explicit
        set(const allocator_type& __a)
        : _M_t(_Compare(), _Key_alloc_type(__a)) { }
  
        /// Allocator-extended copy constructor.
        set(const set& __x, const allocator_type& __a)
        : _M_t(__x._M_t, _Key_alloc_type(__a)) { }
  
        /// Allocator-extended move constructor.
        set(set&& __x, const allocator_type& __a)
        noexcept(is_nothrow_copy_constructible<_Compare>::value
  	       && _Alloc_traits::_S_always_equal())
        : _M_t(std::move(__x._M_t), _Key_alloc_type(__a)) { }
  
        /// Allocator-extended initialier-list constructor.
        set(initializer_list<value_type> __l, const allocator_type& __a)
        : _M_t(_Compare(), _Key_alloc_type(__a))
        { _M_t._M_insert_unique(__l.begin(), __l.end()); }
  
        /// Allocator-extended range constructor.
        template<typename _InputIterator>
          set(_InputIterator __first, _InputIterator __last,
  	    const allocator_type& __a)
  	: _M_t(_Compare(), _Key_alloc_type(__a))
          { _M_t._M_insert_unique(__first, __last); }
  #endif
  
        /**
         *  @brief  %Set assignment operator.
         *  @param  __x  A %set of identical element and allocator types.
         *
         *  All the elements of @a __x are copied, but unlike the copy
         *  constructor, the allocator object is not copied.
         */
        set&
        operator=(const set& __x)
        {
  	_M_t = __x._M_t;
  	return *this;
        }
  
  #if __cplusplus >= 201103L
        /// Move assignment operator.
        set&
        operator=(set&&) = default;
  
        /**
         *  @brief  %Set list assignment operator.
         *  @param  __l  An initializer_list.
         *
         *  This function fills a %set with copies of the elements in the
         *  initializer list @a __l.
         *
         *  Note that the assignment completely changes the %set and
         *  that the resulting %set's size is the same as the number
         *  of elements assigned.  Old data may be lost.
         */
        set&
        operator=(initializer_list<value_type> __l)
        {
  	_M_t._M_assign_unique(__l.begin(), __l.end());
  	return *this;
        }
  #endif
  
        // accessors:
  
        ///  Returns the comparison object with which the %set was constructed.
        key_compare
        key_comp() const
        { return _M_t.key_comp(); }
        ///  Returns the comparison object with which the %set was constructed.
        value_compare
        value_comp() const
        { return _M_t.key_comp(); }
        ///  Returns the allocator object with which the %set was constructed.
        allocator_type
        get_allocator() const _GLIBCXX_NOEXCEPT
        { return allocator_type(_M_t.get_allocator()); }
  
        /**
         *  Returns a read-only (constant) iterator that points to the first
         *  element in the %set.  Iteration is done in ascending order according
         *  to the keys.
         */
        iterator
        begin() const _GLIBCXX_NOEXCEPT
        { return _M_t.begin(); }
  
        /**
         *  Returns a read-only (constant) iterator that points one past the last
         *  element in the %set.  Iteration is done in ascending order according
         *  to the keys.
         */
        iterator
        end() const _GLIBCXX_NOEXCEPT
        { return _M_t.end(); }
  
        /**
         *  Returns a read-only (constant) iterator that points to the last
         *  element in the %set.  Iteration is done in descending order according
         *  to the keys.
         */
        reverse_iterator
        rbegin() const _GLIBCXX_NOEXCEPT
        { return _M_t.rbegin(); }
  
        /**
         *  Returns a read-only (constant) reverse iterator that points to the
         *  last pair in the %set.  Iteration is done in descending order
         *  according to the keys.
         */
        reverse_iterator
        rend() const _GLIBCXX_NOEXCEPT
        { return _M_t.rend(); }
  
  #if __cplusplus >= 201103L
        /**
         *  Returns a read-only (constant) iterator that points to the first
         *  element in the %set.  Iteration is done in ascending order according
         *  to the keys.
         */
        iterator
        cbegin() const noexcept
        { return _M_t.begin(); }
  
        /**
         *  Returns a read-only (constant) iterator that points one past the last
         *  element in the %set.  Iteration is done in ascending order according
         *  to the keys.
         */
        iterator
        cend() const noexcept
        { return _M_t.end(); }
  
        /**
         *  Returns a read-only (constant) iterator that points to the last
         *  element in the %set.  Iteration is done in descending order according
         *  to the keys.
         */
        reverse_iterator
        crbegin() const noexcept
        { return _M_t.rbegin(); }
  
        /**
         *  Returns a read-only (constant) reverse iterator that points to the
         *  last pair in the %set.  Iteration is done in descending order
         *  according to the keys.
         */
        reverse_iterator
        crend() const noexcept
        { return _M_t.rend(); }
  #endif
  
        ///  Returns true if the %set is empty.
        bool
        empty() const _GLIBCXX_NOEXCEPT
        { return _M_t.empty(); }
  
        ///  Returns the size of the %set.
        size_type
        size() const _GLIBCXX_NOEXCEPT
        { return _M_t.size(); }
  
        ///  Returns the maximum size of the %set.
        size_type
        max_size() const _GLIBCXX_NOEXCEPT
        { return _M_t.max_size(); }
  
        /**
         *  @brief  Swaps data with another %set.
         *  @param  __x  A %set of the same element and allocator types.
         *
         *  This exchanges the elements between two sets in constant
         *  time.  (It is only swapping a pointer, an integer, and an
         *  instance of the @c Compare type (which itself is often
         *  stateless and empty), so it should be quite fast.)  Note
         *  that the global std::swap() function is specialized such
         *  that std::swap(s1,s2) will feed to this function.
         */
        void
        swap(set& __x)
  #if __cplusplus >= 201103L
        noexcept(_Alloc_traits::_S_nothrow_swap())
  #endif
        { _M_t.swap(__x._M_t); }
  
        // insert/erase
  #if __cplusplus >= 201103L
        /**
         *  @brief Attempts to build and insert an element into the %set.
         *  @param __args  Arguments used to generate an element.
         *  @return  A pair, of which the first element is an iterator that points
         *           to the possibly inserted element, and the second is a bool
         *           that is true if the element was actually inserted.
         *
         *  This function attempts to build and insert an element into the %set.
         *  A %set relies on unique keys and thus an element is only inserted if
         *  it is not already present in the %set.
         *
         *  Insertion requires logarithmic time.
         */
        template<typename... _Args>
  	std::pair<iterator, bool>
  	emplace(_Args&&... __args)
  	{ return _M_t._M_emplace_unique(std::forward<_Args>(__args)...); }
  
        /**
         *  @brief Attempts to insert an element into the %set.
         *  @param  __pos  An iterator that serves as a hint as to where the
         *                element should be inserted.
         *  @param  __args  Arguments used to generate the element to be
         *                 inserted.
         *  @return An iterator that points to the element with key equivalent to
         *          the one generated from @a __args (may or may not be the
         *          element itself).
         *
         *  This function is not concerned about whether the insertion took place,
         *  and thus does not return a boolean like the single-argument emplace()
         *  does.  Note that the first parameter is only a hint and can
         *  potentially improve the performance of the insertion process.  A bad
         *  hint would cause no gains in efficiency.
         *
         *  For more on @a hinting, see:
         *  https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
         *
         *  Insertion requires logarithmic time (if the hint is not taken).
         */
        template<typename... _Args>
  	iterator
  	emplace_hint(const_iterator __pos, _Args&&... __args)
  	{
  	  return _M_t._M_emplace_hint_unique(__pos,
  					     std::forward<_Args>(__args)...);
  	}
  #endif
  
        /**
         *  @brief Attempts to insert an element into the %set.
         *  @param  __x  Element to be inserted.
         *  @return  A pair, of which the first element is an iterator that points
         *           to the possibly inserted element, and the second is a bool
         *           that is true if the element was actually inserted.
         *
         *  This function attempts to insert an element into the %set.  A %set
         *  relies on unique keys and thus an element is only inserted if it is
         *  not already present in the %set.
         *
         *  Insertion requires logarithmic time.
         */
        std::pair<iterator, bool>
        insert(const value_type& __x)
        {
  	std::pair<typename _Rep_type::iterator, bool> __p =
  	  _M_t._M_insert_unique(__x);
  	return std::pair<iterator, bool>(__p.first, __p.second);
        }
  
  #if __cplusplus >= 201103L
        std::pair<iterator, bool>
        insert(value_type&& __x)
        {
  	std::pair<typename _Rep_type::iterator, bool> __p =
  	  _M_t._M_insert_unique(std::move(__x));
  	return std::pair<iterator, bool>(__p.first, __p.second);
        }
  #endif
  
        /**
         *  @brief Attempts to insert an element into the %set.
         *  @param  __position  An iterator that serves as a hint as to where the
         *                    element should be inserted.
         *  @param  __x  Element to be inserted.
         *  @return An iterator that points to the element with key of
         *           @a __x (may or may not be the element passed in).
         *
         *  This function is not concerned about whether the insertion took place,
         *  and thus does not return a boolean like the single-argument insert()
         *  does.  Note that the first parameter is only a hint and can
         *  potentially improve the performance of the insertion process.  A bad
         *  hint would cause no gains in efficiency.
         *
         *  For more on @a hinting, see:
         *  https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
         *
         *  Insertion requires logarithmic time (if the hint is not taken).
         */
        iterator
        insert(const_iterator __position, const value_type& __x)
        { return _M_t._M_insert_unique_(__position, __x); }
  
  #if __cplusplus >= 201103L
        iterator
        insert(const_iterator __position, value_type&& __x)
        { return _M_t._M_insert_unique_(__position, std::move(__x)); }
  #endif
  
        /**
         *  @brief A template function that attempts to insert a range
         *  of elements.
         *  @param  __first  Iterator pointing to the start of the range to be
         *                   inserted.
         *  @param  __last  Iterator pointing to the end of the range.
         *
         *  Complexity similar to that of the range constructor.
         */
        template<typename _InputIterator>
  	void
  	insert(_InputIterator __first, _InputIterator __last)
  	{ _M_t._M_insert_unique(__first, __last); }
  
  #if __cplusplus >= 201103L
        /**
         *  @brief Attempts to insert a list of elements into the %set.
         *  @param  __l  A std::initializer_list<value_type> of elements
         *               to be inserted.
         *
         *  Complexity similar to that of the range constructor.
         */
        void
        insert(initializer_list<value_type> __l)
        { this->insert(__l.begin(), __l.end()); }
  #endif
  
  #if __cplusplus >= 201103L
        // _GLIBCXX_RESOLVE_LIB_DEFECTS
        // DR 130. Associative erase should return an iterator.
        /**
         *  @brief Erases an element from a %set.
         *  @param  __position  An iterator pointing to the element to be erased.
         *  @return An iterator pointing to the element immediately following
         *          @a __position prior to the element being erased. If no such
         *          element exists, end() is returned.
         *
         *  This function erases an element, pointed to by the given iterator,
         *  from a %set.  Note that this function only erases the element, and
         *  that if the element is itself a pointer, the pointed-to memory is not
         *  touched in any way.  Managing the pointer is the user's
         *  responsibility.
         */
        _GLIBCXX_ABI_TAG_CXX11
        iterator
        erase(const_iterator __position)
        { return _M_t.erase(__position); }
  #else
        /**
         *  @brief Erases an element from a %set.
         *  @param  position  An iterator pointing to the element to be erased.
         *
         *  This function erases an element, pointed to by the given iterator,
         *  from a %set.  Note that this function only erases the element, and
         *  that if the element is itself a pointer, the pointed-to memory is not
         *  touched in any way.  Managing the pointer is the user's
         *  responsibility.
         */
        void
        erase(iterator __position)
        { _M_t.erase(__position); }
  #endif
  
        /**
         *  @brief Erases elements according to the provided key.
         *  @param  __x  Key of element to be erased.
         *  @return  The number of elements erased.
         *
         *  This function erases all the elements located by the given key from
         *  a %set.
         *  Note that this function only erases the element, and that if
         *  the element is itself a pointer, the pointed-to memory is not touched
         *  in any way.  Managing the pointer is the user's responsibility.
         */
        size_type
        erase(const key_type& __x)
        { return _M_t.erase(__x); }
  
  #if __cplusplus >= 201103L
        // _GLIBCXX_RESOLVE_LIB_DEFECTS
        // DR 130. Associative erase should return an iterator.
        /**
         *  @brief Erases a [__first,__last) range of elements from a %set.
         *  @param  __first  Iterator pointing to the start of the range to be
         *                 erased.
  
         *  @param __last Iterator pointing to the end of the range to
         *  be erased.
         *  @return The iterator @a __last.
         *
         *  This function erases a sequence of elements from a %set.
         *  Note that this function only erases the element, and that if
         *  the element is itself a pointer, the pointed-to memory is not touched
         *  in any way.  Managing the pointer is the user's responsibility.
         */
        _GLIBCXX_ABI_TAG_CXX11
        iterator
        erase(const_iterator __first, const_iterator __last)
        { return _M_t.erase(__first, __last); }
  #else
        /**
         *  @brief Erases a [first,last) range of elements from a %set.
         *  @param  __first  Iterator pointing to the start of the range to be
         *                 erased.
         *  @param __last Iterator pointing to the end of the range to
         *  be erased.
         *
         *  This function erases a sequence of elements from a %set.
         *  Note that this function only erases the element, and that if
         *  the element is itself a pointer, the pointed-to memory is not touched
         *  in any way.  Managing the pointer is the user's responsibility.
         */
        void
        erase(iterator __first, iterator __last)
        { _M_t.erase(__first, __last); }
  #endif
  
        /**
         *  Erases all elements in a %set.  Note that this function only erases
         *  the elements, and that if the elements themselves are pointers, the
         *  pointed-to memory is not touched in any way.  Managing the pointer is
         *  the user's responsibility.
         */
        void
        clear() _GLIBCXX_NOEXCEPT
        { _M_t.clear(); }
  
        // set operations:
  
        //@{
        /**
         *  @brief  Finds the number of elements.
         *  @param  __x  Element to located.
         *  @return  Number of elements with specified key.
         *
         *  This function only makes sense for multisets; for set the result will
         *  either be 0 (not present) or 1 (present).
         */
        size_type
        count(const key_type& __x) const
        { return _M_t.find(__x) == _M_t.end() ? 0 : 1; }
  
  #if __cplusplus > 201103L
        template<typename _Kt>
  	auto
  	count(const _Kt& __x) const
  	-> decltype(_M_t._M_count_tr(__x))
  	{ return _M_t._M_find_tr(__x) == _M_t.end() ? 0 : 1; }
  #endif
        //@}
  
        // _GLIBCXX_RESOLVE_LIB_DEFECTS
        // 214.  set::find() missing const overload
        //@{
        /**
         *  @brief Tries to locate an element in a %set.
         *  @param  __x  Element to be located.
         *  @return  Iterator pointing to sought-after element, or end() if not
         *           found.
         *
         *  This function takes a key and tries to locate the element with which
         *  the key matches.  If successful the function returns an iterator
         *  pointing to the sought after element.  If unsuccessful it returns the
         *  past-the-end ( @c end() ) iterator.
         */
        iterator
        find(const key_type& __x)
        { return _M_t.find(__x); }
  
        const_iterator
        find(const key_type& __x) const
        { return _M_t.find(__x); }
  
  #if __cplusplus > 201103L
        template<typename _Kt>
  	auto
  	find(const _Kt& __x)
  	-> decltype(iterator{_M_t._M_find_tr(__x)})
  	{ return iterator{_M_t._M_find_tr(__x)}; }
  
        template<typename _Kt>
  	auto
  	find(const _Kt& __x) const
  	-> decltype(const_iterator{_M_t._M_find_tr(__x)})
  	{ return const_iterator{_M_t._M_find_tr(__x)}; }
  #endif
        //@}
  
        //@{
        /**
         *  @brief Finds the beginning of a subsequence matching given key.
         *  @param  __x  Key to be located.
         *  @return  Iterator pointing to first element equal to or greater
         *           than key, or end().
         *
         *  This function returns the first element of a subsequence of elements
         *  that matches the given key.  If unsuccessful it returns an iterator
         *  pointing to the first element that has a greater value than given key
         *  or end() if no such element exists.
         */
        iterator
        lower_bound(const key_type& __x)
        { return _M_t.lower_bound(__x); }
  
        const_iterator
        lower_bound(const key_type& __x) const
        { return _M_t.lower_bound(__x); }
  
  #if __cplusplus > 201103L
        template<typename _Kt>
  	auto
  	lower_bound(const _Kt& __x)
  	-> decltype(_M_t._M_lower_bound_tr(__x))
  	{ return _M_t._M_lower_bound_tr(__x); }
  
        template<typename _Kt>
  	auto
  	lower_bound(const _Kt& __x) const
  	-> decltype(_M_t._M_lower_bound_tr(__x))
  	{ return _M_t._M_lower_bound_tr(__x); }
  #endif
        //@}
  
        //@{
        /**
         *  @brief Finds the end of a subsequence matching given key.
         *  @param  __x  Key to be located.
         *  @return Iterator pointing to the first element
         *          greater than key, or end().
         */
        iterator
        upper_bound(const key_type& __x)
        { return _M_t.upper_bound(__x); }
  
        const_iterator
        upper_bound(const key_type& __x) const
        { return _M_t.upper_bound(__x); }
  
  #if __cplusplus > 201103L
        template<typename _Kt>
  	auto
  	upper_bound(const _Kt& __x)
  	-> decltype(_M_t._M_upper_bound_tr(__x))
  	{ return _M_t._M_upper_bound_tr(__x); }
  
        template<typename _Kt>
  	auto
  	upper_bound(const _Kt& __x) const
  	-> decltype(_M_t._M_upper_bound_tr(__x))
  	{ return _M_t._M_upper_bound_tr(__x); }
  #endif
        //@}
  
        //@{
        /**
         *  @brief Finds a subsequence matching given key.
         *  @param  __x  Key to be located.
         *  @return  Pair of iterators that possibly points to the subsequence
         *           matching given key.
         *
         *  This function is equivalent to
         *  @code
         *    std::make_pair(c.lower_bound(val),
         *                   c.upper_bound(val))
         *  @endcode
         *  (but is faster than making the calls separately).
         *
         *  This function probably only makes sense for multisets.
         */
        std::pair<iterator, iterator>
        equal_range(const key_type& __x)
        { return _M_t.equal_range(__x); }
  
        std::pair<const_iterator, const_iterator>
        equal_range(const key_type& __x) const
        { return _M_t.equal_range(__x); }
  
  #if __cplusplus > 201103L
        template<typename _Kt>
  	auto
  	equal_range(const _Kt& __x)
  	-> decltype(_M_t._M_equal_range_tr(__x))
  	{ return _M_t._M_equal_range_tr(__x); }
  
        template<typename _Kt>
  	auto
  	equal_range(const _Kt& __x) const
  	-> decltype(_M_t._M_equal_range_tr(__x))
  	{ return _M_t._M_equal_range_tr(__x); }
  #endif
        //@}
  
        template<typename _K1, typename _C1, typename _A1>
  	friend bool
  	operator==(const set<_K1, _C1, _A1>&, const set<_K1, _C1, _A1>&);
  
        template<typename _K1, typename _C1, typename _A1>
  	friend bool
  	operator<(const set<_K1, _C1, _A1>&, const set<_K1, _C1, _A1>&);
      };
  
  
    /**
     *  @brief  Set equality comparison.
     *  @param  __x  A %set.
     *  @param  __y  A %set of the same type as @a x.
     *  @return  True iff the size and elements of the sets are equal.
     *
     *  This is an equivalence relation.  It is linear in the size of the sets.
     *  Sets are considered equivalent if their sizes are equal, and if
     *  corresponding elements compare equal.
    */
    template<typename _Key, typename _Compare, typename _Alloc>
      inline bool
      operator==(const set<_Key, _Compare, _Alloc>& __x,
  	       const set<_Key, _Compare, _Alloc>& __y)
      { return __x._M_t == __y._M_t; }
  
    /**
     *  @brief  Set ordering relation.
     *  @param  __x  A %set.
     *  @param  __y  A %set of the same type as @a x.
     *  @return  True iff @a __x is lexicographically less than @a __y.
     *
     *  This is a total ordering relation.  It is linear in the size of the
     *  sets.  The elements must be comparable with @c <.
     *
     *  See std::lexicographical_compare() for how the determination is made.
    */
    template<typename _Key, typename _Compare, typename _Alloc>
      inline bool
      operator<(const set<_Key, _Compare, _Alloc>& __x,
  	      const set<_Key, _Compare, _Alloc>& __y)
      { return __x._M_t < __y._M_t; }
  
    ///  Returns !(x == y).
    template<typename _Key, typename _Compare, typename _Alloc>
      inline bool
      operator!=(const set<_Key, _Compare, _Alloc>& __x,
  	       const set<_Key, _Compare, _Alloc>& __y)
      { return !(__x == __y); }
  
    ///  Returns y < x.
    template<typename _Key, typename _Compare, typename _Alloc>
      inline bool
      operator>(const set<_Key, _Compare, _Alloc>& __x,
  	      const set<_Key, _Compare, _Alloc>& __y)
      { return __y < __x; }
  
    ///  Returns !(y < x)
    template<typename _Key, typename _Compare, typename _Alloc>
      inline bool
      operator<=(const set<_Key, _Compare, _Alloc>& __x,
  	       const set<_Key, _Compare, _Alloc>& __y)
      { return !(__y < __x); }
  
    ///  Returns !(x < y)
    template<typename _Key, typename _Compare, typename _Alloc>
      inline bool
      operator>=(const set<_Key, _Compare, _Alloc>& __x,
  	       const set<_Key, _Compare, _Alloc>& __y)
      { return !(__x < __y); }
  
    /// See std::set::swap().
    template<typename _Key, typename _Compare, typename _Alloc>
      inline void
      swap(set<_Key, _Compare, _Alloc>& __x, set<_Key, _Compare, _Alloc>& __y)
      { __x.swap(__y); }
  
  _GLIBCXX_END_NAMESPACE_CONTAINER
  } //namespace std
  #endif /* _STL_SET_H */
  