libstdc++-v3/include/bits/stl_algo.h - gcc - Git at Google

 // Algorithm implimentation -*- C++ -*-

 // Copyright (C) 2001 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 2, 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.

 // You should have received a copy of the GNU General Public License along
 // with this library; see the file COPYING.  If not, write to the Free
 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
 // USA.

 // As a special exception, you may use this file as part of a free software
 // library without restriction.  Specifically, if other files instantiate
 // templates or use macros or inline functions from this file, or you compile
 // this file and link it with other files to produce an executable, this
 // file does not by itself cause the resulting executable to be covered by
 // the GNU General Public License.  This exception does not however
 // invalidate any other reasons why the executable file might be covered by
 // the GNU General Public License.

 /*
  *
  * 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
  * 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 stl_algo.h
  *  This is an internal header file, included by other library headers.
  *  You should not attempt to use it directly.
  */

 #ifndef __GLIBCPP_INTERNAL_ALGO_H
 #define __GLIBCPP_INTERNAL_ALGO_H

 #include <bits/stl_heap.h>

 // See concept_check.h for the __glibcpp_*_requires macros.

 namespace std
 {

   // __median (an extension, not present in the C++ standard).

   template<typename _Tp>
   inline const _Tp&
     __median(const _Tp& __a, const _Tp& __b, const _Tp& __c)
     {
       // concept requirements
       __glibcpp_function_requires(_LessThanComparableConcept<_Tp>)
       if (__a < __b)
 	if (__b < __c)
 	  return __b;
 	else if (__a < __c)
 	  return __c;
 	else
 	  return __a;
       else if (__a < __c)
 	return __a;
       else if (__b < __c)
 	return __c;
       else
 	return __b;
     }

   template<typename _Tp, typename _Compare>
     inline const _Tp&
     __median(const _Tp& __a, const _Tp& __b, const _Tp& __c, _Compare __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_BinaryFunctionConcept<_Compare, bool, _Tp, _Tp>)
       if (__comp(__a, __b))
 	if (__comp(__b, __c))
 	  return __b;
 	else if (__comp(__a, __c))
 	  return __c;
 	else
 	  return __a;
       else if (__comp(__a, __c))
 	return __a;
       else if (__comp(__b, __c))
 	return __c;
       else
 	return __b;
     }

   // for_each.  Apply a function to every element of a range.
   template<typename _InputIter, typename _Function>
     _Function
     for_each(_InputIter __first, _InputIter __last, _Function __f)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       for ( ; __first != __last; ++__first)
 	__f(*__first);
       return __f;
     }

   // find and find_if.

   template<typename _InputIter, typename _Tp>
     inline _InputIter
     find(_InputIter __first, _InputIter __last,
 	 const _Tp& __val,
 	 input_iterator_tag)
     {
       while (__first != __last && !(*__first == __val))
 	++__first;
       return __first;
     }

   template<typename _InputIter, typename _Predicate>
     inline _InputIter
     find_if(_InputIter __first, _InputIter __last,
 	    _Predicate __pred,
 	    input_iterator_tag)
     {
       while (__first != __last && !__pred(*__first))
 	++__first;
       return __first;
     }

   template<typename _RandomAccessIter, typename _Tp>
     _RandomAccessIter
     find(_RandomAccessIter __first, _RandomAccessIter __last,
 	 const _Tp& __val,
 	 random_access_iterator_tag)
     {
       typename iterator_traits<_RandomAccessIter>::difference_type __trip_count
 	= (__last - __first) >> 2;

       for ( ; __trip_count > 0 ; --__trip_count) {
 	if (*__first == __val) return __first;
 	++__first;

 	if (*__first == __val) return __first;
 	++__first;

 	if (*__first == __val) return __first;
 	++__first;

 	if (*__first == __val) return __first;
 	++__first;
       }

       switch(__last - __first) {
       case 3:
 	if (*__first == __val) return __first;
 	++__first;
       case 2:
 	if (*__first == __val) return __first;
 	++__first;
       case 1:
 	if (*__first == __val) return __first;
 	++__first;
       case 0:
       default:
 	return __last;
       }
     }

   template<typename _RandomAccessIter, typename _Predicate>
     _RandomAccessIter
     find_if(_RandomAccessIter __first, _RandomAccessIter __last,
 	    _Predicate __pred,
 	    random_access_iterator_tag)
     {
       typename iterator_traits<_RandomAccessIter>::difference_type __trip_count
 	= (__last - __first) >> 2;

       for ( ; __trip_count > 0 ; --__trip_count) {
 	if (__pred(*__first)) return __first;
 	++__first;

 	if (__pred(*__first)) return __first;
 	++__first;

 	if (__pred(*__first)) return __first;
 	++__first;

 	if (__pred(*__first)) return __first;
 	++__first;
       }

       switch(__last - __first) {
       case 3:
 	if (__pred(*__first)) return __first;
 	++__first;
       case 2:
 	if (__pred(*__first)) return __first;
 	++__first;
       case 1:
 	if (__pred(*__first)) return __first;
 	++__first;
       case 0:
       default:
 	return __last;
       }
     }

   template<typename _InputIter, typename _Tp>
     inline _InputIter
     find(_InputIter __first, _InputIter __last,
 	 const _Tp& __val)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_EqualOpConcept<
 		typename iterator_traits<_InputIter>::value_type, _Tp>)
       return find(__first, __last, __val, __iterator_category(__first));
     }

   template<typename _InputIter, typename _Predicate>
     inline _InputIter
     find_if(_InputIter __first, _InputIter __last,
 	    _Predicate __pred)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_UnaryPredicateConcept<_Predicate,
 	      typename iterator_traits<_InputIter>::value_type>)
       return find_if(__first, __last, __pred, __iterator_category(__first));
     }

   // adjacent_find.

   template<typename _ForwardIter>
     _ForwardIter
     adjacent_find(_ForwardIter __first, _ForwardIter __last)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_EqualityComparableConcept<
 	    typename iterator_traits<_ForwardIter>::value_type>)
       if (__first == __last)
 	return __last;
       _ForwardIter __next = __first;
       while(++__next != __last) {
 	if (*__first == *__next)
 	  return __first;
 	__first = __next;
       }
       return __last;
     }

   template<typename _ForwardIter, typename _BinaryPredicate>
     _ForwardIter
     adjacent_find(_ForwardIter __first, _ForwardIter __last,
 		  _BinaryPredicate __binary_pred)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
 	    typename iterator_traits<_ForwardIter>::value_type,
 	    typename iterator_traits<_ForwardIter>::value_type>)
       if (__first == __last)
 	return __last;
       _ForwardIter __next = __first;
       while(++__next != __last) {
 	if (__binary_pred(*__first, *__next))
 	  return __first;
 	__first = __next;
       }
       return __last;
     }

   // count and count_if.  There are two version of each, one whose return type
   // type is void and one (present only if we have partial specialization)
   // whose return type is iterator_traits<_InputIter>::difference_type.  The
   // C++ standard only has the latter version, but the former, which was present
   // in the HP STL, is retained for backward compatibility.

   template<typename _InputIter, typename _Tp, typename _Size>
     void
     count(_InputIter __first, _InputIter __last,
 	  const _Tp& __value,
 	  _Size& __n)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_EqualityComparableConcept<
 	    typename iterator_traits<_InputIter>::value_type >)
       __glibcpp_function_requires(_EqualityComparableConcept<_Tp>)
       for ( ; __first != __last; ++__first)
 	if (*__first == __value)
 	  ++__n;
     }

   template<typename _InputIter, typename _Predicate, typename _Size>
     void
     count_if(_InputIter __first, _InputIter __last,
 	     _Predicate __pred,
 	     _Size& __n)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_UnaryPredicateConcept<_Predicate,
 	    typename iterator_traits<_InputIter>::value_type>)
       for ( ; __first != __last; ++__first)
 	if (__pred(*__first))
 	  ++__n;
     }

   template<typename _InputIter, typename _Tp>
     typename iterator_traits<_InputIter>::difference_type
     count(_InputIter __first, _InputIter __last, const _Tp& __value)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_EqualityComparableConcept<
 	    typename iterator_traits<_InputIter>::value_type >)
       __glibcpp_function_requires(_EqualityComparableConcept<_Tp>)
       typename iterator_traits<_InputIter>::difference_type __n = 0;
       for ( ; __first != __last; ++__first)
 	if (*__first == __value)
 	  ++__n;
       return __n;
     }

   template<typename _InputIter, typename _Predicate>
     typename iterator_traits<_InputIter>::difference_type
     count_if(_InputIter __first, _InputIter __last, _Predicate __pred)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_UnaryPredicateConcept<_Predicate,
 	    typename iterator_traits<_InputIter>::value_type>)
       typename iterator_traits<_InputIter>::difference_type __n = 0;
       for ( ; __first != __last; ++__first)
 	if (__pred(*__first))
 	  ++__n;
       return __n;
     }


   // search.

   template<typename _ForwardIter1, typename _ForwardIter2>
     _ForwardIter1
     search(_ForwardIter1 __first1, _ForwardIter1 __last1,
 	   _ForwardIter2 __first2, _ForwardIter2 __last2)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter1>)
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter2>)
       __glibcpp_function_requires(_EqualOpConcept<
 	    typename iterator_traits<_ForwardIter1>::value_type,
 	    typename iterator_traits<_ForwardIter2>::value_type>)

       // Test for empty ranges
       if (__first1 == __last1 || __first2 == __last2)
 	return __first1;

       // Test for a pattern of length 1.
       _ForwardIter2 __tmp(__first2);
       ++__tmp;
       if (__tmp == __last2)
 	return find(__first1, __last1, *__first2);

       // General case.

       _ForwardIter2 __p1, __p;

       __p1 = __first2; ++__p1;

       _ForwardIter1 __current = __first1;

       while (__first1 != __last1) {
 	__first1 = find(__first1, __last1, *__first2);
 	if (__first1 == __last1)
 	  return __last1;

 	__p = __p1;
 	__current = __first1;
 	if (++__current == __last1)
 	  return __last1;

 	while (*__current == *__p) {
 	  if (++__p == __last2)
 	    return __first1;
 	  if (++__current == __last1)
 	    return __last1;
 	}

 	++__first1;
       }
       return __first1;
     }

   template<typename _ForwardIter1, typename _ForwardIter2, typename _BinaryPred>
     _ForwardIter1
     search(_ForwardIter1 __first1, _ForwardIter1 __last1,
 	   _ForwardIter2 __first2, _ForwardIter2 __last2,
 	   _BinaryPred  __predicate)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter1>)
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter2>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_BinaryPred,
 	    typename iterator_traits<_ForwardIter1>::value_type,
 	    typename iterator_traits<_ForwardIter2>::value_type>)

       // Test for empty ranges
       if (__first1 == __last1 || __first2 == __last2)
 	return __first1;

       // Test for a pattern of length 1.
       _ForwardIter2 __tmp(__first2);
       ++__tmp;
       if (__tmp == __last2) {
 	while (__first1 != __last1 && !__predicate(*__first1, *__first2))
 	  ++__first1;
 	return __first1;
       }

       // General case.

       _ForwardIter2 __p1, __p;

       __p1 = __first2; ++__p1;

       _ForwardIter1 __current = __first1;

       while (__first1 != __last1) {
 	while (__first1 != __last1) {
 	  if (__predicate(*__first1, *__first2))
 	    break;
 	  ++__first1;
 	}
 	while (__first1 != __last1 && !__predicate(*__first1, *__first2))
 	  ++__first1;
 	if (__first1 == __last1)
 	  return __last1;

 	__p = __p1;
 	__current = __first1;
 	if (++__current == __last1) return __last1;

 	while (__predicate(*__current, *__p)) {
 	  if (++__p == __last2)
 	    return __first1;
 	  if (++__current == __last1)
 	    return __last1;
 	}

 	++__first1;
       }
       return __first1;
     }

   // search_n.  Search for __count consecutive copies of __val.

   template<typename _ForwardIter, typename _Integer, typename _Tp>
     _ForwardIter
     search_n(_ForwardIter __first, _ForwardIter __last,
 	     _Integer __count, const _Tp& __val)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_EqualityComparableConcept<
 	    typename iterator_traits<_ForwardIter>::value_type>)
       __glibcpp_function_requires(_EqualityComparableConcept<_Tp>)

       if (__count <= 0)
 	return __first;
       else {
 	__first = find(__first, __last, __val);
 	while (__first != __last) {
 	  _Integer __n = __count - 1;
 	  _ForwardIter __i = __first;
 	  ++__i;
 	  while (__i != __last && __n != 0 && *__i == __val) {
 	    ++__i;
 	    --__n;
 	  }
 	  if (__n == 0)
 	    return __first;
 	  else
 	    __first = find(__i, __last, __val);
 	}
 	return __last;
       }
     }

   template<typename _ForwardIter, typename _Integer, typename _Tp,
            typename _BinaryPred>
     _ForwardIter
     search_n(_ForwardIter __first, _ForwardIter __last,
 	     _Integer __count, const _Tp& __val,
 	     _BinaryPred __binary_pred)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_BinaryPred,
 	    typename iterator_traits<_ForwardIter>::value_type, _Tp>)

       if (__count <= 0)
 	return __first;
       else {
 	while (__first != __last) {
 	  if (__binary_pred(*__first, __val))
 	    break;
 	  ++__first;
 	}
 	while (__first != __last) {
 	  _Integer __n = __count - 1;
 	  _ForwardIter __i = __first;
 	  ++__i;
 	  while (__i != __last && __n != 0 && __binary_pred(*__i, __val)) {
 	    ++__i;
 	    --__n;
 	  }
 	  if (__n == 0)
 	    return __first;
 	  else {
 	    while (__i != __last) {
 	      if (__binary_pred(*__i, __val))
 		break;
 	      ++__i;
 	    }
 	    __first = __i;
 	  }
 	}
 	return __last;
       }
     }

   // swap_ranges

   template<typename _ForwardIter1, typename _ForwardIter2>
     _ForwardIter2
     swap_ranges(_ForwardIter1 __first1, _ForwardIter1 __last1,
 		_ForwardIter2 __first2)
     {
       // concept requirements
       __glibcpp_function_requires(_Mutable_ForwardIteratorConcept<_ForwardIter1>)
       __glibcpp_function_requires(_Mutable_ForwardIteratorConcept<_ForwardIter2>)
       __glibcpp_function_requires(_ConvertibleConcept<
 	    typename iterator_traits<_ForwardIter1>::value_type,
 	    typename iterator_traits<_ForwardIter2>::value_type>)
       __glibcpp_function_requires(_ConvertibleConcept<
 	    typename iterator_traits<_ForwardIter2>::value_type,
 	    typename iterator_traits<_ForwardIter1>::value_type>)

       for ( ; __first1 != __last1; ++__first1, ++__first2)
 	iter_swap(__first1, __first2);
       return __first2;
     }

   // transform

   template<typename _InputIter, typename _OutputIter, typename _UnaryOperation>
     _OutputIter
     transform(_InputIter __first, _InputIter __last,
 	      _OutputIter __result, _UnaryOperation __unary_op)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
     /* XXX
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    // should be "the type returned by _UnaryOperation"
 	    typename iterator_traits<_InputIter>::value_type>)
     */

       for ( ; __first != __last; ++__first, ++__result)
 	*__result = __unary_op(*__first);
       return __result;
     }

   template<typename _InputIter1, typename _InputIter2, typename _OutputIter,
 	   typename _BinaryOperation>
     _OutputIter
     transform(_InputIter1 __first1, _InputIter1 __last1,
 	      _InputIter2 __first2, _OutputIter __result,
 	      _BinaryOperation __binary_op)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
     /* XXX
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    // should be "the type returned by _BinaryOperation"
 	    typename iterator_traits<_InputIter1>::value_type>)
     */

       for ( ; __first1 != __last1; ++__first1, ++__first2, ++__result)
 	*__result = __binary_op(*__first1, *__first2);
       return __result;
     }

   // replace, replace_if, replace_copy, replace_copy_if

   template<typename _ForwardIter, typename _Tp>
     void
     replace(_ForwardIter __first, _ForwardIter __last,
 	    const _Tp& __old_value, const _Tp& __new_value)
     {
       // concept requirements
       __glibcpp_function_requires(_Mutable_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_EqualOpConcept<
 	    typename iterator_traits<_ForwardIter>::value_type, _Tp>)
       __glibcpp_function_requires(_ConvertibleConcept<_Tp,
 	    typename iterator_traits<_ForwardIter>::value_type>)

       for ( ; __first != __last; ++__first)
 	if (*__first == __old_value)
 	  *__first = __new_value;
     }

   template<typename _ForwardIter, typename _Predicate, typename _Tp>
     void
     replace_if(_ForwardIter __first, _ForwardIter __last,
 	       _Predicate __pred, const _Tp& __new_value)
     {
       // concept requirements
       __glibcpp_function_requires(_Mutable_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_ConvertibleConcept<_Tp,
 	    typename iterator_traits<_ForwardIter>::value_type>)
       __glibcpp_function_requires(_UnaryPredicateConcept<_Predicate,
 	    typename iterator_traits<_ForwardIter>::value_type>)

       for ( ; __first != __last; ++__first)
 	if (__pred(*__first))
 	  *__first = __new_value;
     }

   template<typename _InputIter, typename _OutputIter, typename _Tp>
     _OutputIter
     replace_copy(_InputIter __first, _InputIter __last,
 		 _OutputIter __result,
 		 const _Tp& __old_value, const _Tp& __new_value)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter>::value_type>)
       __glibcpp_function_requires(_EqualOpConcept<
 	    typename iterator_traits<_InputIter>::value_type, _Tp>)

       for ( ; __first != __last; ++__first, ++__result)
 	*__result = *__first == __old_value ? __new_value : *__first;
       return __result;
     }

   template<typename _InputIter, typename _OutputIter, typename _Predicate,
            typename _Tp>
     _OutputIter
     replace_copy_if(_InputIter __first, _InputIter __last,
 		    _OutputIter __result,
 		    _Predicate __pred, const _Tp& __new_value)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter>::value_type>)
       __glibcpp_function_requires(_UnaryPredicateConcept<_Predicate,
 	    typename iterator_traits<_InputIter>::value_type>)

       for ( ; __first != __last; ++__first, ++__result)
 	*__result = __pred(*__first) ? __new_value : *__first;
       return __result;
     }

   // generate and generate_n

   template<typename _ForwardIter, typename _Generator>
     void
     generate(_ForwardIter __first, _ForwardIter __last, _Generator __gen)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_GeneratorConcept<_Generator,
 	    typename iterator_traits<_ForwardIter>::value_type>)

       for ( ; __first != __last; ++__first)
 	*__first = __gen();
     }

   template<typename _OutputIter, typename _Size, typename _Generator>
     _OutputIter
     generate_n(_OutputIter __first, _Size __n, _Generator __gen)
     {
     /*
       // XXX concept requirements
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    "the return type of _Generator" ??   >)
     */

       for ( ; __n > 0; --__n, ++__first)
 	*__first = __gen();
       return __first;
     }

   // remove, remove_if, remove_copy, remove_copy_if

   template<typename _InputIter, typename _OutputIter, typename _Tp>
     _OutputIter
     remove_copy(_InputIter __first, _InputIter __last,
 		_OutputIter __result, const _Tp& __value)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter>::value_type>)
       __glibcpp_function_requires(_EqualOpConcept<
 	    typename iterator_traits<_InputIter>::value_type, _Tp>)

       for ( ; __first != __last; ++__first)
 	if (!(*__first == __value)) {
 	  *__result = *__first;
 	  ++__result;
 	}
       return __result;
     }

   template<typename _InputIter, typename _OutputIter, typename _Predicate>
     _OutputIter
     remove_copy_if(_InputIter __first, _InputIter __last,
 		   _OutputIter __result, _Predicate __pred)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter>::value_type>)
       __glibcpp_function_requires(_UnaryPredicateConcept<_Predicate,
 	    typename iterator_traits<_InputIter>::value_type>)

       for ( ; __first != __last; ++__first)
 	if (!__pred(*__first)) {
 	  *__result = *__first;
 	  ++__result;
 	}
       return __result;
     }

   template<typename _ForwardIter, typename _Tp>
     _ForwardIter
     remove(_ForwardIter __first, _ForwardIter __last,
 	   const _Tp& __value)
     {
       // concept requirements
       __glibcpp_function_requires(_Mutable_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_ConvertibleConcept<_Tp,
 	    typename iterator_traits<_ForwardIter>::value_type>)
       __glibcpp_function_requires(_EqualOpConcept<
 	    typename iterator_traits<_ForwardIter>::value_type, _Tp>)

       __first = find(__first, __last, __value);
       _ForwardIter __i = __first;
       return __first == __last ? __first
 			       : remove_copy(++__i, __last, __first, __value);
     }

   template<typename _ForwardIter, typename _Predicate>
     _ForwardIter
     remove_if(_ForwardIter __first, _ForwardIter __last,
 	      _Predicate __pred)
     {
       // concept requirements
       __glibcpp_function_requires(_Mutable_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_UnaryPredicateConcept<_Predicate,
 	    typename iterator_traits<_ForwardIter>::value_type>)

       __first = find_if(__first, __last, __pred);
       _ForwardIter __i = __first;
       return __first == __last ? __first
 			       : remove_copy_if(++__i, __last, __first, __pred);
     }

   template<typename _InputIter, typename _OutputIter>
     _OutputIter
     __unique_copy(_InputIter __first, _InputIter __last,
 		  _OutputIter __result,
 		  output_iterator_tag)
     {
       // concept requirements -- taken care of in dispatching function
       typename iterator_traits<_InputIter>::value_type __value = *__first;
       *__result = __value;
       while (++__first != __last)
 	if (!(__value == *__first)) {
 	  __value = *__first;
 	  *++__result = __value;
 	}
       return ++__result;
     }

   template<typename _InputIter, typename _ForwardIter>
     _ForwardIter
     __unique_copy(_InputIter __first, _InputIter __last,
 		  _ForwardIter __result,
 		  forward_iterator_tag)
     {
       // concept requirements -- taken care of in dispatching function
       *__result = *__first;
       while (++__first != __last)
 	if (!(*__result == *__first))
 	  *++__result = *__first;
       return ++__result;
     }

   template<typename _InputIter, typename _OutputIter>
     inline _OutputIter
     unique_copy(_InputIter __first, _InputIter __last,
 		_OutputIter __result)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter>::value_type>)
       __glibcpp_function_requires(_EqualityComparableConcept<
 	    typename iterator_traits<_InputIter>::value_type>)

       typedef typename iterator_traits<_OutputIter>::iterator_category _IterType;

       if (__first == __last) return __result;
       return __unique_copy(__first, __last, __result, _IterType());
     }

   template<typename _InputIter, typename _OutputIter, typename _BinaryPredicate>
     _OutputIter
     __unique_copy(_InputIter __first, _InputIter __last,
 		  _OutputIter __result,
 		  _BinaryPredicate __binary_pred,
 		  output_iterator_tag)
     {
       // concept requirements -- iterators already checked
       __glibcpp_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
 	  typename iterator_traits<_InputIter>::value_type,
 	  typename iterator_traits<_InputIter>::value_type>)

       typename iterator_traits<_InputIter>::value_type __value = *__first;
       *__result = __value;
       while (++__first != __last)
 	if (!__binary_pred(__value, *__first)) {
 	  __value = *__first;
 	  *++__result = __value;
 	}
       return ++__result;
     }

   template<typename _InputIter, typename _ForwardIter, typename _BinaryPredicate>
     _ForwardIter
     __unique_copy(_InputIter __first, _InputIter __last,
 		  _ForwardIter __result,
 		  _BinaryPredicate __binary_pred,
 		  forward_iterator_tag)
     {
       // concept requirements -- iterators already checked
       __glibcpp_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
 	    typename iterator_traits<_ForwardIter>::value_type,
 	    typename iterator_traits<_InputIter>::value_type>)

       *__result = *__first;
       while (++__first != __last)
 	if (!__binary_pred(*__result, *__first)) *++__result = *__first;
       return ++__result;
     }

   template<typename _InputIter, typename _OutputIter, typename _BinaryPredicate>
     inline _OutputIter
     unique_copy(_InputIter __first, _InputIter __last,
 		_OutputIter __result,
 		_BinaryPredicate __binary_pred)
     {
       // concept requirements -- predicates checked later
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter>::value_type>)

       typedef typename iterator_traits<_OutputIter>::iterator_category _IterType;

       if (__first == __last) return __result;
       return __unique_copy(__first, __last,
 __result, __binary_pred, _IterType());
     }

   template<typename _ForwardIter>
     _ForwardIter
     unique(_ForwardIter __first, _ForwardIter __last)
     {
 	  // concept requirements
 	  __glibcpp_function_requires(_Mutable_ForwardIteratorConcept<_ForwardIter>)
 	  __glibcpp_function_requires(_EqualityComparableConcept<
 		    typename iterator_traits<_ForwardIter>::value_type>)

 	  __first = adjacent_find(__first, __last);
 	  return unique_copy(__first, __last, __first);
     }

   template<typename _ForwardIter, typename _BinaryPredicate>
     _ForwardIter
     unique(_ForwardIter __first, _ForwardIter __last,
            _BinaryPredicate __binary_pred)
     {
       // concept requirements
       __glibcpp_function_requires(_Mutable_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
 		typename iterator_traits<_ForwardIter>::value_type,
 		typename iterator_traits<_ForwardIter>::value_type>)

       __first = adjacent_find(__first, __last, __binary_pred);
       return unique_copy(__first, __last, __first, __binary_pred);
     }

   template<typename _BidirectionalIter>
     void
     __reverse(_BidirectionalIter __first, _BidirectionalIter __last,
 			  bidirectional_iterator_tag)
     {
 	  while (true)
 	    if (__first == __last || __first == --__last)
 		  return;
 	    else
 		  iter_swap(__first++, __last);
     }

   template<typename _RandomAccessIter>
     void
     __reverse(_RandomAccessIter __first, _RandomAccessIter __last,
 			  random_access_iterator_tag)
     {
 	  while (__first < __last)
 	    iter_swap(__first++, --__last);
     }

   template<typename _BidirectionalIter>
     inline void
     reverse(_BidirectionalIter __first, _BidirectionalIter __last)
     {
 	  // concept requirements
 	  __glibcpp_function_requires(_Mutable_BidirectionalIteratorConcept<
 		    _BidirectionalIter>)
 	  __reverse(__first, __last, __iterator_category(__first));
     }

   template<typename _BidirectionalIter, typename _OutputIter>
     _OutputIter
     reverse_copy(_BidirectionalIter __first, _BidirectionalIter __last,
 			     _OutputIter __result)
     {
       // concept requirements
       __glibcpp_function_requires(_BidirectionalIteratorConcept<_BidirectionalIter>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 		typename iterator_traits<_BidirectionalIter>::value_type>)

       while (__first != __last) {
 	--__last;
 	*__result = *__last;
 	++__result;
       }
       return __result;
     }

   /// This is a helper function for the rotate algorithm specialized on RAIs.

   template<typename _EuclideanRingElement>
     _EuclideanRingElement
     __gcd(_EuclideanRingElement __m, _EuclideanRingElement __n)
     {
       while (__n != 0) {
 	_EuclideanRingElement __t = __m % __n;
 	__m = __n;
 	__n = __t;
       }
       return __m;
     }

   template<typename _ForwardIter>
     void
     __rotate(_ForwardIter __first,
 	     _ForwardIter __middle,
 	     _ForwardIter __last,
 	      forward_iterator_tag)
     {
       if ((__first == __middle) || (__last  == __middle))
 	return;

       _ForwardIter __first2 = __middle;
       do {
 	swap(*__first++, *__first2++);
 	if (__first == __middle)
 	  __middle = __first2;
       } while (__first2 != __last);

       __first2 = __middle;

       while (__first2 != __last) {
 	swap(*__first++, *__first2++);
 	if (__first == __middle)
 	  __middle = __first2;
 	else if (__first2 == __last)
 	  __first2 = __middle;
       }
     }

   template<typename _BidirectionalIter>
     void
     __rotate(_BidirectionalIter __first,
 	     _BidirectionalIter __middle,
 	     _BidirectionalIter __last,
 	      bidirectional_iterator_tag)
     {
       // concept requirements
       __glibcpp_function_requires(_Mutable_BidirectionalIteratorConcept<
 	    _BidirectionalIter>)

       if ((__first == __middle) || (__last  == __middle))
 	return;

       __reverse(__first,  __middle, bidirectional_iterator_tag());
       __reverse(__middle, __last,   bidirectional_iterator_tag());

       while (__first != __middle && __middle != __last)
 	swap (*__first++, *--__last);

       if (__first == __middle) {
 	__reverse(__middle, __last,   bidirectional_iterator_tag());
       }
       else {
 	__reverse(__first,  __middle, bidirectional_iterator_tag());
       }
     }

   template<typename _RandomAccessIter>
     void
     __rotate(_RandomAccessIter __first,
 	     _RandomAccessIter __middle,
 	     _RandomAccessIter __last,
 	     random_access_iterator_tag)
     {
       // concept requirements
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<
 	    _RandomAccessIter>)

       if ((__first == __middle) || (__last  == __middle))
 	return;

       typedef typename iterator_traits<_RandomAccessIter>::difference_type _Distance;
       typedef typename iterator_traits<_RandomAccessIter>::value_type _ValueType;

       _Distance __n = __last   - __first;
       _Distance __k = __middle - __first;
       _Distance __l = __n - __k;

       if (__k == __l) {
 	swap_ranges(__first, __middle, __middle);
 	return;
       }

       _Distance __d = __gcd(__n, __k);

       for (_Distance __i = 0; __i < __d; __i++) {
 	_ValueType __tmp = *__first;
 	_RandomAccessIter __p = __first;

 	if (__k < __l) {
 	  for (_Distance __j = 0; __j < __l/__d; __j++) {
 	    if (__p > __first + __l) {
 	      *__p = *(__p - __l);
 	      __p -= __l;
 	    }

 	    *__p = *(__p + __k);
 	    __p += __k;
 	  }
 	}

 	else {
 	  for (_Distance __j = 0; __j < __k/__d - 1; __j ++) {
 	    if (__p < __last - __k) {
 	      *__p = *(__p + __k);
 	      __p += __k;
 	    }

 	    *__p = * (__p - __l);
 	    __p -= __l;
 	  }
 	}

 	*__p = __tmp;
 	++__first;
       }
     }

   template<typename _ForwardIter>
     inline void
     rotate(_ForwardIter __first, _ForwardIter __middle, _ForwardIter __last)
     {
       // concept requirements
       __glibcpp_function_requires(_Mutable_ForwardIteratorConcept<_ForwardIter>)

       typedef typename iterator_traits<_ForwardIter>::iterator_category _IterType;
       __rotate(__first, __middle, __last, _IterType());
     }

   template<typename _ForwardIter, typename _OutputIter>
     _OutputIter
     rotate_copy(_ForwardIter __first, _ForwardIter __middle,
                 _ForwardIter __last, _OutputIter __result)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 		typename iterator_traits<_ForwardIter>::value_type>)

       return copy(__first, __middle, copy(__middle, __last, __result));
     }

   // Return a random number in the range [0, __n).  This function encapsulates
   // whether we're using rand (part of the standard C library) or lrand48
   // (not standard, but a much better choice whenever it's available).
   template<typename _Distance>
     inline _Distance
     __random_number(_Distance __n)
     {
   #ifdef _GLIBCPP_HAVE_DRAND48
       return lrand48() % __n;
   #else
       return rand() % __n;
   #endif
     }

   /// 25.2.11 random_shuffle().

   template<typename _RandomAccessIter>
     inline void
     random_shuffle(_RandomAccessIter __first, _RandomAccessIter __last)
     {
       // concept requirements
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<
 	    _RandomAccessIter>)

       if (__first == __last) return;
       for (_RandomAccessIter __i = __first + 1; __i != __last; ++__i)
 	iter_swap(__i, __first + __random_number((__i - __first) + 1));
     }

   template<typename _RandomAccessIter, typename _RandomNumberGenerator>
     void
     random_shuffle(_RandomAccessIter __first, _RandomAccessIter __last,
 		   _RandomNumberGenerator& __rand)
     {
       // concept requirements
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<
 	    _RandomAccessIter>)

       if (__first == __last) return;
       for (_RandomAccessIter __i = __first + 1; __i != __last; ++__i)
 	iter_swap(__i, __first + __rand((__i - __first) + 1));
     }

   // random_sample and random_sample_n (extensions, not part of the standard).

   template<typename _ForwardIter, typename _OutputIter, typename _Distance>
     _OutputIter
     random_sample_n(_ForwardIter __first, _ForwardIter __last,
                     _OutputIter __out, const _Distance __n)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 		typename iterator_traits<_ForwardIter>::value_type>)

       _Distance __remaining = distance(__first, __last);
       _Distance __m = min(__n, __remaining);

       while (__m > 0) {
 	if (__random_number(__remaining) < __m) {
 	      *__out = *__first;
 	      ++__out;
 	      --__m;
 	}

 	--__remaining;
 	++__first;
       }
       return __out;
     }

   template<typename _ForwardIter, typename _OutputIter, typename _Distance,
 	   typename _RandomNumberGenerator>
     _OutputIter
     random_sample_n(_ForwardIter __first, _ForwardIter __last,
                    _OutputIter __out, const _Distance __n,
 		   _RandomNumberGenerator& __rand)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 		typename iterator_traits<_ForwardIter>::value_type>)
       __glibcpp_function_requires(_UnaryFunctionConcept<
 		_RandomNumberGenerator, _Distance, _Distance>)

       _Distance __remaining = distance(__first, __last);
       _Distance __m = min(__n, __remaining);

       while (__m > 0) {
 	if (__rand(__remaining) < __m) {
 	      *__out = *__first;
 	      ++__out;
 	      --__m;
 	}

 	--__remaining;
 	++__first;
       }
       return __out;
     }

   template<typename _InputIter, typename _RandomAccessIter, typename _Distance>
     _RandomAccessIter
     __random_sample(_InputIter __first, _InputIter __last,
 		    _RandomAccessIter __out,
 		    const _Distance __n)
     {
       _Distance __m = 0;
       _Distance __t = __n;
       for ( ; __first != __last && __m < __n; ++__m, ++__first)
 	__out[__m] = *__first;

       while (__first != __last) {
 	++__t;
 	_Distance __M = __random_number(__t);
 	if (__M < __n)
 	  __out[__M] = *__first;
 	++__first;
       }

       return __out + __m;
     }

   template<typename _InputIter, typename _RandomAccessIter,
 	   typename _RandomNumberGenerator, typename _Distance>
     _RandomAccessIter
     __random_sample(_InputIter __first, _InputIter __last,
 		    _RandomAccessIter __out,
 		    _RandomNumberGenerator& __rand,
 		    const _Distance __n)
     {
       // concept requirements
       __glibcpp_function_requires(_UnaryFunctionConcept<
 	    _RandomNumberGenerator, _Distance, _Distance>)

       _Distance __m = 0;
       _Distance __t = __n;
       for ( ; __first != __last && __m < __n; ++__m, ++__first)
 	__out[__m] = *__first;

       while (__first != __last) {
 	++__t;
 	_Distance __M = __rand(__t);
 	if (__M < __n)
 	  __out[__M] = *__first;
 	++__first;
       }

       return __out + __m;
     }

   template<typename _InputIter, typename _RandomAccessIter>
     inline _RandomAccessIter
     random_sample(_InputIter __first, _InputIter __last,
 		  _RandomAccessIter __out_first, _RandomAccessIter __out_last)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<
 	    _RandomAccessIter>)

       return __random_sample(__first, __last,
 			     __out_first, __out_last - __out_first);
     }


   template<typename _InputIter, typename _RandomAccessIter,
 	   typename _RandomNumberGenerator>
     inline _RandomAccessIter
     random_sample(_InputIter __first, _InputIter __last,
 		  _RandomAccessIter __out_first, _RandomAccessIter __out_last,
 		  _RandomNumberGenerator& __rand)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<
 	    _RandomAccessIter>)

       return __random_sample(__first, __last,
 			     __out_first, __rand,
 			     __out_last - __out_first);
     }

   // partition, stable_partition, and their auxiliary functions

   template<typename _ForwardIter, typename _Predicate>
     _ForwardIter
     __partition(_ForwardIter __first, _ForwardIter __last,
 		_Predicate   __pred,
 		forward_iterator_tag)
     {
       if (__first == __last) return __first;

       while (__pred(*__first))
 	if (++__first == __last) return __first;

       _ForwardIter __next = __first;

       while (++__next != __last)
 	if (__pred(*__next)) {
 	  swap(*__first, *__next);
 	  ++__first;
 	}

       return __first;
     }

   template<typename _BidirectionalIter, typename _Predicate>
     _BidirectionalIter
     __partition(_BidirectionalIter __first, _BidirectionalIter __last,
 		_Predicate __pred,
 		bidirectional_iterator_tag)
     {
       while (true) {
 	while (true)
 	  if (__first == __last)
 	    return __first;
 	  else if (__pred(*__first))
 	    ++__first;
 	  else
 	    break;
 	--__last;
 	while (true)
 	  if (__first == __last)
 	    return __first;
 	  else if (!__pred(*__last))
 	    --__last;
 	  else
 	    break;
 	iter_swap(__first, __last);
 	++__first;
       }
     }

   template<typename _ForwardIter, typename _Predicate>
     inline _ForwardIter
     partition(_ForwardIter __first, _ForwardIter __last,
 	      _Predicate   __pred)
     {
       // concept requirements
       __glibcpp_function_requires(_Mutable_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_UnaryPredicateConcept<_Predicate,
 	    typename iterator_traits<_ForwardIter>::value_type>)

       return __partition(__first, __last, __pred, __iterator_category(__first));
     }


   template<typename _ForwardIter, typename _Predicate, typename _Distance>
     _ForwardIter
     __inplace_stable_partition(_ForwardIter __first, _ForwardIter __last,
 			       _Predicate __pred, _Distance __len)
     {
       if (__len == 1)
 	return __pred(*__first) ? __last : __first;
       _ForwardIter __middle = __first;
       advance(__middle, __len / 2);
       _ForwardIter __begin = __inplace_stable_partition(__first, __middle,
 							__pred,
 							__len / 2);
       _ForwardIter __end = __inplace_stable_partition(__middle, __last,
 						      __pred,
 						      __len - __len / 2);
       rotate(__begin, __middle, __end);
       advance(__begin, distance(__middle, __end));
       return __begin;
     }

   template<typename _ForwardIter, typename _Pointer, typename _Predicate,
 	   typename _Distance>
     _ForwardIter
     __stable_partition_adaptive(_ForwardIter __first, _ForwardIter __last,
 				_Predicate __pred, _Distance __len,
 				_Pointer __buffer,
 				_Distance __buffer_size)
     {
       if (__len <= __buffer_size) {
 	_ForwardIter __result1 = __first;
 	_Pointer __result2 = __buffer;
 	for ( ; __first != __last ; ++__first)
 	  if (__pred(*__first)) {
 	    *__result1 = *__first;
 	    ++__result1;
 	  }
 	  else {
 	    *__result2 = *__first;
 	    ++__result2;
 	  }
 	copy(__buffer, __result2, __result1);
 	return __result1;
       }
       else {
 	_ForwardIter __middle = __first;
 	advance(__middle, __len / 2);
 	_ForwardIter __begin = __stable_partition_adaptive(__first, __middle,
 							   __pred,
 							   __len / 2,
 							   __buffer, __buffer_size);
 	_ForwardIter __end = __stable_partition_adaptive( __middle, __last,
 							  __pred,
 							  __len - __len / 2,
 							  __buffer, __buffer_size);
 	rotate(__begin, __middle, __end);
 	advance(__begin, distance(__middle, __end));
 	return __begin;
       }
     }

   template<typename _ForwardIter, typename _Predicate>
     _ForwardIter
     stable_partition(_ForwardIter __first, _ForwardIter __last,
 		     _Predicate __pred)
     {
       // concept requirements
       __glibcpp_function_requires(_Mutable_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_UnaryPredicateConcept<_Predicate,
 	    typename iterator_traits<_ForwardIter>::value_type>)

       if (__first == __last)
 	return __first;
       else
       {
 	typedef typename iterator_traits<_ForwardIter>::value_type _ValueType;
 	typedef typename iterator_traits<_ForwardIter>::difference_type _DistanceType;

 	_Temporary_buffer<_ForwardIter, _ValueType> __buf(__first, __last);
 	if (__buf.size() > 0)
 	  return __stable_partition_adaptive(__first, __last, __pred,
 					     _DistanceType(__buf.requested_size()),
 					     __buf.begin(), __buf.size());
 	else
 	  return __inplace_stable_partition(__first, __last, __pred,
 					    _DistanceType(__buf.requested_size()));
       }
     }

   template<typename _RandomAccessIter, typename _Tp>
     _RandomAccessIter
     __unguarded_partition(_RandomAccessIter __first, _RandomAccessIter __last,
 			  _Tp __pivot)
     {
       while (true) {
 	while (*__first < __pivot)
 	  ++__first;
 	--__last;
 	while (__pivot < *__last)
 	  --__last;
 	if (!(__first < __last))
 	  return __first;
 	iter_swap(__first, __last);
 	++__first;
       }
     }

   template<typename _RandomAccessIter, typename _Tp, typename _Compare>
     _RandomAccessIter
     __unguarded_partition(_RandomAccessIter __first, _RandomAccessIter __last,
 			  _Tp __pivot, _Compare __comp)
     {
       while (true) {
 	while (__comp(*__first, __pivot))
 	  ++__first;
 	--__last;
 	while (__comp(__pivot, *__last))
 	  --__last;
 	if (!(__first < __last))
 	  return __first;
 	iter_swap(__first, __last);
 	++__first;
       }
     }

   const int __stl_threshold = 16;

   // sort() and its auxiliary functions.

   template<typename _RandomAccessIter, typename _Tp>
     void
     __unguarded_linear_insert(_RandomAccessIter __last, _Tp __val)
     {
       _RandomAccessIter __next = __last;
       --__next;
       while (__val < *__next) {
 	*__last = *__next;
 	__last = __next;
 	--__next;
       }
       *__last = __val;
     }

   template<typename _RandomAccessIter, typename _Tp, typename _Compare>
     void
     __unguarded_linear_insert(_RandomAccessIter __last, _Tp __val, _Compare __comp)
     {
       _RandomAccessIter __next = __last;
       --__next;
       while (__comp(__val, *__next)) {
 	*__last = *__next;
 	__last = __next;
 	--__next;
       }
       *__last = __val;
     }

   template<typename _RandomAccessIter>
     void
     __insertion_sort(_RandomAccessIter __first, _RandomAccessIter __last)
     {
       if (__first == __last) return;

       for (_RandomAccessIter __i = __first + 1; __i != __last; ++__i)
       {
 	typename iterator_traits<_RandomAccessIter>::value_type __val = *__i;
 	if (__val < *__first) {
 	  copy_backward(__first, __i, __i + 1);
 	  *__first = __val;
 	}
 	else
 	  __unguarded_linear_insert(__i, __val);
       }
     }

   template<typename _RandomAccessIter, typename _Compare>
     void
     __insertion_sort(_RandomAccessIter __first, _RandomAccessIter __last,
 		     _Compare __comp)
     {
       if (__first == __last) return;

       for (_RandomAccessIter __i = __first + 1; __i != __last; ++__i)
       {
 	typename iterator_traits<_RandomAccessIter>::value_type __val = *__i;
 	if (__comp(__val, *__first)) {
 	  copy_backward(__first, __i, __i + 1);
 	  *__first = __val;
 	}
 	else
 	  __unguarded_linear_insert(__i, __val, __comp);
       }
     }

   template<typename _RandomAccessIter>
     inline void
     __unguarded_insertion_sort(_RandomAccessIter __first, _RandomAccessIter __last)
     {
       typedef typename iterator_traits<_RandomAccessIter>::value_type _ValueType;

       for (_RandomAccessIter __i = __first; __i != __last; ++__i)
 	__unguarded_linear_insert(__i, _ValueType(*__i));
     }

   template<typename _RandomAccessIter, typename _Compare>
     inline void
     __unguarded_insertion_sort(_RandomAccessIter __first, _RandomAccessIter __last,
 			       _Compare __comp)
     {
       typedef typename iterator_traits<_RandomAccessIter>::value_type _ValueType;

       for (_RandomAccessIter __i = __first; __i != __last; ++__i)
 	__unguarded_linear_insert(__i, _ValueType(*__i), __comp);
     }

   template<typename _RandomAccessIter>
     void
     __final_insertion_sort(_RandomAccessIter __first, _RandomAccessIter __last)
     {
       if (__last - __first > __stl_threshold) {
 	__insertion_sort(__first, __first + __stl_threshold);
 	__unguarded_insertion_sort(__first + __stl_threshold, __last);
       }
       else
 	__insertion_sort(__first, __last);
     }

   template<typename _RandomAccessIter, typename _Compare>
     void
     __final_insertion_sort(_RandomAccessIter __first, _RandomAccessIter __last,
 			   _Compare __comp)
     {
       if (__last - __first > __stl_threshold) {
 	__insertion_sort(__first, __first + __stl_threshold, __comp);
 	__unguarded_insertion_sort(__first + __stl_threshold, __last, __comp);
       }
       else
 	__insertion_sort(__first, __last, __comp);
     }

   template<typename _Size>
     inline _Size
     __lg(_Size __n)
     {
       _Size __k;
       for (__k = 0; __n != 1; __n >>= 1) ++__k;
       return __k;
     }

   template<typename _RandomAccessIter, typename _Size>
     void
     __introsort_loop(_RandomAccessIter __first, _RandomAccessIter __last,
 		     _Size __depth_limit)
     {
       typedef typename iterator_traits<_RandomAccessIter>::value_type _ValueType;

       while (__last - __first > __stl_threshold) {
 	if (__depth_limit == 0) {
 	  partial_sort(__first, __last, __last);
 	  return;
 	}
 	--__depth_limit;
 	_RandomAccessIter __cut =
 	  __unguarded_partition(__first, __last,
 				_ValueType(__median(*__first,
 						    *(__first + (__last - __first)/2),
 						    *(__last - 1))));
 	__introsort_loop(__cut, __last, __depth_limit);
 	__last = __cut;
       }
     }

   template<typename _RandomAccessIter, typename _Size, typename _Compare>
     void
     __introsort_loop(_RandomAccessIter __first, _RandomAccessIter __last,
 		     _Size __depth_limit, _Compare __comp)
     {
       typedef typename iterator_traits<_RandomAccessIter>::value_type _ValueType;

       while (__last - __first > __stl_threshold) {
 	if (__depth_limit == 0) {
 	  partial_sort(__first, __last, __last, __comp);
 	  return;
 	}
 	--__depth_limit;
 	_RandomAccessIter __cut =
 	  __unguarded_partition(__first, __last,
 				_ValueType(__median(*__first,
 						    *(__first + (__last - __first)/2),
 						    *(__last - 1), __comp)),
 	   __comp);
 	__introsort_loop(__cut, __last, __depth_limit, __comp);
 	__last = __cut;
       }
     }

   template<typename _RandomAccessIter>
     inline void
     sort(_RandomAccessIter __first, _RandomAccessIter __last)
     {
       typedef typename iterator_traits<_RandomAccessIter>::value_type _ValueType;

       // concept requirements
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<
 	    _RandomAccessIter>)
       __glibcpp_function_requires(_LessThanComparableConcept<_ValueType>)

       if (__first != __last) {
 	__introsort_loop(__first, __last, __lg(__last - __first) * 2);
 	__final_insertion_sort(__first, __last);
       }
     }

   template<typename _RandomAccessIter, typename _Compare>
     inline void
     sort(_RandomAccessIter __first, _RandomAccessIter __last, _Compare __comp)
     {
       typedef typename iterator_traits<_RandomAccessIter>::value_type _ValueType;

       // concept requirements
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<
 	    _RandomAccessIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare, _ValueType, _ValueType>)

       if (__first != __last) {
 	__introsort_loop(__first, __last, __lg(__last - __first) * 2, __comp);
 	__final_insertion_sort(__first, __last, __comp);
       }
     }

   // stable_sort() and its auxiliary functions.

   template<typename _RandomAccessIter>
     void
     __inplace_stable_sort(_RandomAccessIter __first, _RandomAccessIter __last)
     {
       if (__last - __first < 15) {
 	__insertion_sort(__first, __last);
 	return;
       }
       _RandomAccessIter __middle = __first + (__last - __first) / 2;
       __inplace_stable_sort(__first, __middle);
       __inplace_stable_sort(__middle, __last);
       __merge_without_buffer(__first, __middle, __last,
 			     __middle - __first,
 			     __last - __middle);
     }

   template<typename _RandomAccessIter, typename _Compare>
     void
     __inplace_stable_sort(_RandomAccessIter __first, _RandomAccessIter __last,
 			  _Compare __comp)
     {
       if (__last - __first < 15) {
 	__insertion_sort(__first, __last, __comp);
 	return;
       }
       _RandomAccessIter __middle = __first + (__last - __first) / 2;
       __inplace_stable_sort(__first, __middle, __comp);
       __inplace_stable_sort(__middle, __last, __comp);
       __merge_without_buffer(__first, __middle, __last,
 			     __middle - __first,
 			     __last - __middle,
 			     __comp);
     }

   template<typename _RandomAccessIter1, typename _RandomAccessIter2,
 	   typename _Distance>
     void
     __merge_sort_loop(_RandomAccessIter1 __first, _RandomAccessIter1 __last,
 		      _RandomAccessIter2 __result, _Distance __step_size)
     {
       _Distance __two_step = 2 * __step_size;

       while (__last - __first >= __two_step) {
 	__result = merge(__first, __first + __step_size,
 			 __first + __step_size, __first + __two_step,
 			 __result);
 	__first += __two_step;
       }

       __step_size = min(_Distance(__last - __first), __step_size);
       merge(__first, __first + __step_size, __first + __step_size, __last,
 	    __result);
     }

   template<typename _RandomAccessIter1, typename _RandomAccessIter2,
 	   typename _Distance, typename _Compare>
     void
     __merge_sort_loop(_RandomAccessIter1 __first, _RandomAccessIter1 __last,
 		      _RandomAccessIter2 __result, _Distance __step_size,
 		      _Compare __comp)
     {
       _Distance __two_step = 2 * __step_size;

       while (__last - __first >= __two_step) {
 	__result = merge(__first, __first + __step_size,
 			 __first + __step_size, __first + __two_step,
 			 __result,
 			 __comp);
 	__first += __two_step;
       }
       __step_size = min(_Distance(__last - __first), __step_size);

       merge(__first, __first + __step_size,
 	    __first + __step_size, __last,
 	    __result,
 	    __comp);
     }

   const int __stl_chunk_size = 7;

   template<typename _RandomAccessIter, typename _Distance>
     void
     __chunk_insertion_sort(_RandomAccessIter __first, _RandomAccessIter __last,
 			   _Distance __chunk_size)
     {
       while (__last - __first >= __chunk_size) {
 	__insertion_sort(__first, __first + __chunk_size);
 	__first += __chunk_size;
       }
       __insertion_sort(__first, __last);
     }

   template<typename _RandomAccessIter, typename _Distance, typename _Compare>
     void
     __chunk_insertion_sort(_RandomAccessIter __first, _RandomAccessIter __last,
 			   _Distance __chunk_size, _Compare __comp)
     {
       while (__last - __first >= __chunk_size) {
 	__insertion_sort(__first, __first + __chunk_size, __comp);
 	__first += __chunk_size;
       }
       __insertion_sort(__first, __last, __comp);
     }

   template<typename _RandomAccessIter, typename _Pointer>
     void
     __merge_sort_with_buffer(_RandomAccessIter __first, _RandomAccessIter __last,
                              _Pointer __buffer)
     {
       typedef typename iterator_traits<_RandomAccessIter>::difference_type _Distance;

       _Distance __len = __last - __first;
       _Pointer __buffer_last = __buffer + __len;

       _Distance __step_size = __stl_chunk_size;
       __chunk_insertion_sort(__first, __last, __step_size);

       while (__step_size < __len) {
 	__merge_sort_loop(__first, __last, __buffer, __step_size);
 	__step_size *= 2;
 	__merge_sort_loop(__buffer, __buffer_last, __first, __step_size);
 	__step_size *= 2;
       }
     }

   template<typename _RandomAccessIter, typename _Pointer, typename _Compare>
     void
     __merge_sort_with_buffer(_RandomAccessIter __first, _RandomAccessIter __last,
                              _Pointer __buffer, _Compare __comp)
     {
       typedef typename iterator_traits<_RandomAccessIter>::difference_type _Distance;

       _Distance __len = __last - __first;
       _Pointer __buffer_last = __buffer + __len;

       _Distance __step_size = __stl_chunk_size;
       __chunk_insertion_sort(__first, __last, __step_size, __comp);

       while (__step_size < __len) {
 	__merge_sort_loop(__first, __last, __buffer, __step_size, __comp);
 	__step_size *= 2;
 	__merge_sort_loop(__buffer, __buffer_last, __first, __step_size, __comp);
 	__step_size *= 2;
       }
     }

   template<typename _RandomAccessIter, typename _Pointer, typename _Distance>
     void
     __stable_sort_adaptive(_RandomAccessIter __first, _RandomAccessIter __last,
                            _Pointer __buffer, _Distance __buffer_size)
     {
       _Distance __len = (__last - __first + 1) / 2;
       _RandomAccessIter __middle = __first + __len;
       if (__len > __buffer_size) {
 	__stable_sort_adaptive(__first, __middle, __buffer, __buffer_size);
 	__stable_sort_adaptive(__middle, __last, __buffer, __buffer_size);
       }
       else {
 	__merge_sort_with_buffer(__first, __middle, __buffer);
 	__merge_sort_with_buffer(__middle, __last, __buffer);
       }
       __merge_adaptive(__first, __middle, __last, _Distance(__middle - __first),
                        _Distance(__last - __middle), __buffer, __buffer_size);
     }

   template<typename _RandomAccessIter, typename _Pointer, typename _Distance,
            typename _Compare>
     void
     __stable_sort_adaptive(_RandomAccessIter __first, _RandomAccessIter __last,
                            _Pointer __buffer, _Distance __buffer_size,
                            _Compare __comp)
     {
       _Distance __len = (__last - __first + 1) / 2;
       _RandomAccessIter __middle = __first + __len;
       if (__len > __buffer_size) {
 	__stable_sort_adaptive(__first, __middle, __buffer, __buffer_size,
                                __comp);
 	__stable_sort_adaptive(__middle, __last, __buffer, __buffer_size,
                                __comp);
       }
       else {
 	__merge_sort_with_buffer(__first, __middle, __buffer, __comp);
 	__merge_sort_with_buffer(__middle, __last, __buffer, __comp);
       }
       __merge_adaptive(__first, __middle, __last, _Distance(__middle - __first),
                        _Distance(__last - __middle), __buffer, __buffer_size,
                        __comp);
     }

   template<typename _RandomAccessIter>
     inline void
     stable_sort(_RandomAccessIter __first, _RandomAccessIter __last)
     {
       typedef typename iterator_traits<_RandomAccessIter>::value_type _ValueType;
       typedef typename iterator_traits<_RandomAccessIter>::difference_type _DistanceType;

       // concept requirements
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<
 	    _RandomAccessIter>)
       __glibcpp_function_requires(_LessThanComparableConcept<_ValueType>)

       _Temporary_buffer<_RandomAccessIter, _ValueType> buf(__first, __last);
       if (buf.begin() == 0)
 	__inplace_stable_sort(__first, __last);
       else
 	__stable_sort_adaptive(__first, __last, buf.begin(), _DistanceType(buf.size()));
     }

   template<typename _RandomAccessIter, typename _Compare>
     inline void
     stable_sort(_RandomAccessIter __first, _RandomAccessIter __last, _Compare __comp)
     {
       typedef typename iterator_traits<_RandomAccessIter>::value_type _ValueType;
       typedef typename iterator_traits<_RandomAccessIter>::difference_type _DistanceType;

       // concept requirements
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<
 	    _RandomAccessIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 							  _ValueType, _ValueType>)

       _Temporary_buffer<_RandomAccessIter, _ValueType> buf(__first, __last);
       if (buf.begin() == 0)
 	__inplace_stable_sort(__first, __last, __comp);
       else
 	__stable_sort_adaptive(__first, __last, buf.begin(), _DistanceType(buf.size()),
 			       __comp);
     }

   template<typename _RandomAccessIter>
     void
     partial_sort(_RandomAccessIter __first,
 		 _RandomAccessIter __middle,
 		 _RandomAccessIter __last)
     {
       typedef typename iterator_traits<_RandomAccessIter>::value_type _ValueType;

       // concept requirements
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<
 	    _RandomAccessIter>)
       __glibcpp_function_requires(_LessThanComparableConcept<_ValueType>)

       make_heap(__first, __middle);
       for (_RandomAccessIter __i = __middle; __i < __last; ++__i)
 	if (*__i < *__first)
 	  __pop_heap(__first, __middle, __i, _ValueType(*__i));
       sort_heap(__first, __middle);
     }

   template<typename _RandomAccessIter, typename _Compare>
     void
     partial_sort(_RandomAccessIter __first,
 		 _RandomAccessIter __middle,
 		 _RandomAccessIter __last,
 		 _Compare __comp)
     {
       typedef typename iterator_traits<_RandomAccessIter>::value_type _ValueType;

       // concept requirements
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<
 	    _RandomAccessIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 							  _ValueType, _ValueType>)

       make_heap(__first, __middle, __comp);
       for (_RandomAccessIter __i = __middle; __i < __last; ++__i)
 	if (__comp(*__i, *__first))
 	  __pop_heap(__first, __middle, __i, _ValueType(*__i), __comp);
       sort_heap(__first, __middle, __comp);
     }

   template<typename _InputIter, typename _RandomAccessIter>
     _RandomAccessIter
     partial_sort_copy(_InputIter __first, _InputIter __last,
 		      _RandomAccessIter __result_first,
 		      _RandomAccessIter __result_last)
     {
       typedef typename iterator_traits<_InputIter>::value_type _InputValueType;
       typedef typename iterator_traits<_RandomAccessIter>::value_type _OutputValueType;
       typedef typename iterator_traits<_RandomAccessIter>::difference_type _DistanceType;

       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_ConvertibleConcept<_InputValueType, _OutputValueType>)
       __glibcpp_function_requires(_LessThanComparableConcept<_OutputValueType>)
       __glibcpp_function_requires(_LessThanComparableConcept<_InputValueType>)

       if (__result_first == __result_last) return __result_last;
       _RandomAccessIter __result_real_last = __result_first;
       while(__first != __last && __result_real_last != __result_last) {
 	*__result_real_last = *__first;
 	++__result_real_last;
 	++__first;
       }
       make_heap(__result_first, __result_real_last);
       while (__first != __last) {
 	if (*__first < *__result_first)
 	  __adjust_heap(__result_first, _DistanceType(0),
 			_DistanceType(__result_real_last - __result_first),
 			_InputValueType(*__first));
 	++__first;
       }
       sort_heap(__result_first, __result_real_last);
       return __result_real_last;
     }

   template<typename _InputIter, typename _RandomAccessIter, typename _Compare>
     _RandomAccessIter
     partial_sort_copy(_InputIter __first, _InputIter __last,
 		      _RandomAccessIter __result_first,
 		      _RandomAccessIter __result_last,
 		      _Compare __comp)
     {
       typedef typename iterator_traits<_InputIter>::value_type _InputValueType;
       typedef typename iterator_traits<_RandomAccessIter>::value_type _OutputValueType;
       typedef typename iterator_traits<_RandomAccessIter>::difference_type _DistanceType;

       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<_RandomAccessIter>)
       __glibcpp_function_requires(_ConvertibleConcept<_InputValueType, _OutputValueType>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 				  _OutputValueType, _OutputValueType>)

       if (__result_first == __result_last) return __result_last;
       _RandomAccessIter __result_real_last = __result_first;
       while(__first != __last && __result_real_last != __result_last) {
 	*__result_real_last = *__first;
 	++__result_real_last;
 	++__first;
       }
       make_heap(__result_first, __result_real_last, __comp);
       while (__first != __last) {
 	if (__comp(*__first, *__result_first))
 	  __adjust_heap(__result_first, _DistanceType(0),
 			_DistanceType(__result_real_last - __result_first),
 			_InputValueType(*__first),
 			__comp);
 	++__first;
       }
       sort_heap(__result_first, __result_real_last, __comp);
       return __result_real_last;
     }

   template<typename _RandomAccessIter>
     void
     nth_element(_RandomAccessIter __first,
 		_RandomAccessIter __nth,
 		_RandomAccessIter __last)
     {
       typedef typename iterator_traits<_RandomAccessIter>::value_type _ValueType;

       // concept requirements
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<_RandomAccessIter>)
       __glibcpp_function_requires(_LessThanComparableConcept<_ValueType>)

       while (__last - __first > 3) {
 	_RandomAccessIter __cut =
 	  __unguarded_partition(__first, __last,
 				_ValueType(__median(*__first,
 						    *(__first + (__last - __first)/2),
 						    *(__last - 1))));
 	if (__cut <= __nth)
 	  __first = __cut;
 	else
 	  __last = __cut;
       }
       __insertion_sort(__first, __last);
     }

   template<typename _RandomAccessIter, typename _Compare>
     void
     nth_element(_RandomAccessIter __first,
 		_RandomAccessIter __nth,
 		_RandomAccessIter __last,
 			    _Compare __comp)
     {
       typedef typename iterator_traits<_RandomAccessIter>::value_type _ValueType;

       // concept requirements
       __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<_RandomAccessIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 				  _ValueType, _ValueType>)

       while (__last - __first > 3) {
 	_RandomAccessIter __cut =
 	  __unguarded_partition(__first, __last,
 				_ValueType(__median(*__first,
 						    *(__first + (__last - __first)/2),
 						    *(__last - 1),
 						    __comp)),
 				__comp);
 	if (__cut <= __nth)
 	  __first = __cut;
 	else
 	  __last = __cut;
       }
       __insertion_sort(__first, __last, __comp);
     }


   // Binary search (lower_bound, upper_bound, equal_range, binary_search).

   template<typename _ForwardIter, typename _Tp>
     _ForwardIter
     lower_bound(_ForwardIter __first, _ForwardIter __last, const _Tp& __val)
     {
       typedef typename iterator_traits<_ForwardIter>::value_type _ValueType;
       typedef typename iterator_traits<_ForwardIter>::difference_type _DistanceType;

       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_SameTypeConcept<_Tp, _ValueType>)
       __glibcpp_function_requires(_LessThanComparableConcept<_Tp>)

       _DistanceType __len = distance(__first, __last);
       _DistanceType __half;
       _ForwardIter __middle;

       while (__len > 0) {
 	__half = __len >> 1;
 	__middle = __first;
 	advance(__middle, __half);
 	if (*__middle < __val) {
 	  __first = __middle;
 	  ++__first;
 	  __len = __len - __half - 1;
 	}
 	else
 	  __len = __half;
       }
       return __first;
     }

   template<typename _ForwardIter, typename _Tp, typename _Compare>
     _ForwardIter
     lower_bound(_ForwardIter __first, _ForwardIter __last,
 		const _Tp& __val, _Compare __comp)
     {
       typedef typename iterator_traits<_ForwardIter>::value_type _ValueType;
       typedef typename iterator_traits<_ForwardIter>::difference_type _DistanceType;

       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_SameTypeConcept<_Tp, _ValueType>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare, _Tp, _Tp>)

       _DistanceType __len = distance(__first, __last);
       _DistanceType __half;
       _ForwardIter __middle;

       while (__len > 0) {
 	__half = __len >> 1;
 	__middle = __first;
 	advance(__middle, __half);
 	if (__comp(*__middle, __val)) {
 	  __first = __middle;
 	  ++__first;
 	  __len = __len - __half - 1;
 	}
 	else
 	  __len = __half;
       }
       return __first;
     }

   template<typename _ForwardIter, typename _Tp>
     _ForwardIter
     upper_bound(_ForwardIter __first, _ForwardIter __last, const _Tp& __val)
     {
       typedef typename iterator_traits<_ForwardIter>::value_type _ValueType;
       typedef typename iterator_traits<_ForwardIter>::difference_type _DistanceType;

       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_SameTypeConcept<_Tp, _ValueType>)
       __glibcpp_function_requires(_LessThanComparableConcept<_Tp>)

       _DistanceType __len = distance(__first, __last);
       _DistanceType __half;
       _ForwardIter __middle;

       while (__len > 0) {
 	__half = __len >> 1;
 	__middle = __first;
 	advance(__middle, __half);
 	if (__val < *__middle)
 	  __len = __half;
 	else {
 	  __first = __middle;
 	  ++__first;
 	  __len = __len - __half - 1;
 	}
       }
       return __first;
     }

   template<typename _ForwardIter, typename _Tp, typename _Compare>
     _ForwardIter
     upper_bound(_ForwardIter __first, _ForwardIter __last,
 		const _Tp& __val, _Compare __comp)
     {
       typedef typename iterator_traits<_ForwardIter>::value_type _ValueType;
       typedef typename iterator_traits<_ForwardIter>::difference_type _DistanceType;

       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_SameTypeConcept<_Tp, _ValueType>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare, _Tp, _Tp>)

       _DistanceType __len = distance(__first, __last);
       _DistanceType __half;
       _ForwardIter __middle;

       while (__len > 0) {
 	__half = __len >> 1;
 	__middle = __first;
 	advance(__middle, __half);
 	if (__comp(__val, *__middle))
 	  __len = __half;
 	else {
 	  __first = __middle;
 	  ++__first;
 	  __len = __len - __half - 1;
 	}
       }
       return __first;
     }

   template<typename _ForwardIter, typename _Tp>
     pair<_ForwardIter, _ForwardIter>
     equal_range(_ForwardIter __first, _ForwardIter __last, const _Tp& __val)
     {
       typedef typename iterator_traits<_ForwardIter>::value_type _ValueType;
       typedef typename iterator_traits<_ForwardIter>::difference_type _DistanceType;

       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_SameTypeConcept<_Tp, _ValueType>)
       __glibcpp_function_requires(_LessThanComparableConcept<_Tp>)

       _DistanceType __len = distance(__first, __last);
       _DistanceType __half;
       _ForwardIter __middle, __left, __right;

       while (__len > 0) {
 	__half = __len >> 1;
 	__middle = __first;
 	advance(__middle, __half);
 	if (*__middle < __val) {
 	  __first = __middle;
 	  ++__first;
 	  __len = __len - __half - 1;
 	}
 	else if (__val < *__middle)
 	  __len = __half;
 	else {
 	  __left = lower_bound(__first, __middle, __val);
 	  advance(__first, __len);
 	  __right = upper_bound(++__middle, __first, __val);
 	  return pair<_ForwardIter, _ForwardIter>(__left, __right);
 	}
       }
       return pair<_ForwardIter, _ForwardIter>(__first, __first);
     }

   template<typename _ForwardIter, typename _Tp, typename _Compare>
     pair<_ForwardIter, _ForwardIter>
     equal_range(_ForwardIter __first, _ForwardIter __last, const _Tp& __val,
 		_Compare __comp)
     {
       typedef typename iterator_traits<_ForwardIter>::value_type _ValueType;
       typedef typename iterator_traits<_ForwardIter>::difference_type _DistanceType;

       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_SameTypeConcept<_Tp, _ValueType>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare, _Tp, _Tp>)

       _DistanceType __len = distance(__first, __last);
       _DistanceType __half;
       _ForwardIter __middle, __left, __right;

       while (__len > 0) {
 	__half = __len >> 1;
 	__middle = __first;
 	advance(__middle, __half);
 	if (__comp(*__middle, __val)) {
 	  __first = __middle;
 	  ++__first;
 	  __len = __len - __half - 1;
 	}
 	else if (__comp(__val, *__middle))
 	  __len = __half;
 	else {
 	  __left = lower_bound(__first, __middle, __val, __comp);
 	  advance(__first, __len);
 	  __right = upper_bound(++__middle, __first, __val, __comp);
 	  return pair<_ForwardIter, _ForwardIter>(__left, __right);
 	}
       }
       return pair<_ForwardIter, _ForwardIter>(__first, __first);
     }

   template<typename _ForwardIter, typename _Tp>
     bool
     binary_search(_ForwardIter __first, _ForwardIter __last,
                   const _Tp& __val)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_SameTypeConcept<_Tp,
 		typename iterator_traits<_ForwardIter>::value_type>)
       __glibcpp_function_requires(_LessThanComparableConcept<_Tp>)

       _ForwardIter __i = lower_bound(__first, __last, __val);
       return __i != __last && !(__val < *__i);
     }

   template<typename _ForwardIter, typename _Tp, typename _Compare>
     bool
     binary_search(_ForwardIter __first, _ForwardIter __last,
                   const _Tp& __val, _Compare __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_SameTypeConcept<_Tp,
 		typename iterator_traits<_ForwardIter>::value_type>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare, _Tp, _Tp>)

       _ForwardIter __i = lower_bound(__first, __last, __val, __comp);
       return __i != __last && !__comp(__val, *__i);
     }

   // merge, with and without an explicitly supplied comparison function.

   template<typename _InputIter1, typename _InputIter2, typename _OutputIter>
     _OutputIter
     merge(_InputIter1 __first1, _InputIter1 __last1,
 	  _InputIter2 __first2, _InputIter2 __last2,
 	  _OutputIter __result)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter1>::value_type>)
       __glibcpp_function_requires(_SameTypeConcept<
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)
       __glibcpp_function_requires(_LessThanComparableConcept<
 	    typename iterator_traits<_InputIter1>::value_type>)

       while (__first1 != __last1 && __first2 != __last2) {
 	if (*__first2 < *__first1) {
 	  *__result = *__first2;
 	  ++__first2;
 	}
 	else {
 	  *__result = *__first1;
 	  ++__first1;
 	}
 	++__result;
       }
       return copy(__first2, __last2, copy(__first1, __last1, __result));
     }

   template<typename _InputIter1, typename _InputIter2, typename _OutputIter,
 	   typename _Compare>
     _OutputIter
     merge(_InputIter1 __first1, _InputIter1 __last1,
 	  _InputIter2 __first2, _InputIter2 __last2,
 	  _OutputIter __result, _Compare __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
       __glibcpp_function_requires(_SameTypeConcept<
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter1>::value_type>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)

       while (__first1 != __last1 && __first2 != __last2) {
 	if (__comp(*__first2, *__first1)) {
 	  *__result = *__first2;
 	  ++__first2;
 	}
 	else {
 	  *__result = *__first1;
 	  ++__first1;
 	}
 	++__result;
       }
       return copy(__first2, __last2, copy(__first1, __last1, __result));
     }

   // inplace_merge and its auxiliary functions.

   template<typename _BidirectionalIter, typename _Distance>
     void
     __merge_without_buffer(_BidirectionalIter __first,
 			   _BidirectionalIter __middle,
 			   _BidirectionalIter __last,
 			   _Distance __len1, _Distance __len2)
     {
       if (__len1 == 0 || __len2 == 0)
 	return;
       if (__len1 + __len2 == 2) {
 	if (*__middle < *__first)
 	      iter_swap(__first, __middle);
 	return;
       }
       _BidirectionalIter __first_cut = __first;
       _BidirectionalIter __second_cut = __middle;
       _Distance __len11 = 0;
       _Distance __len22 = 0;
       if (__len1 > __len2) {
 	__len11 = __len1 / 2;
 	advance(__first_cut, __len11);
 	__second_cut = lower_bound(__middle, __last, *__first_cut);
 	__len22 = distance(__middle, __second_cut);
       }
       else {
 	__len22 = __len2 / 2;
 	advance(__second_cut, __len22);
 	__first_cut = upper_bound(__first, __middle, *__second_cut);
 	__len11 = distance(__first, __first_cut);
       }
       rotate(__first_cut, __middle, __second_cut);
       _BidirectionalIter __new_middle = __first_cut;
       advance(__new_middle, distance(__middle, __second_cut));
       __merge_without_buffer(__first, __first_cut, __new_middle,
 			     __len11, __len22);
       __merge_without_buffer(__new_middle, __second_cut, __last,
 			     __len1 - __len11, __len2 - __len22);
     }

   template<typename _BidirectionalIter, typename _Distance, typename _Compare>
     void
     __merge_without_buffer(_BidirectionalIter __first,
                            _BidirectionalIter __middle,
 			   _BidirectionalIter __last,
 			   _Distance __len1, _Distance __len2,
 			   _Compare __comp)
     {
       if (__len1 == 0 || __len2 == 0)
 	return;
       if (__len1 + __len2 == 2) {
 	if (__comp(*__middle, *__first))
 	      iter_swap(__first, __middle);
 	return;
       }
       _BidirectionalIter __first_cut = __first;
       _BidirectionalIter __second_cut = __middle;
       _Distance __len11 = 0;
       _Distance __len22 = 0;
       if (__len1 > __len2) {
 	__len11 = __len1 / 2;
 	advance(__first_cut, __len11);
 	__second_cut = lower_bound(__middle, __last, *__first_cut, __comp);
 	__len22 = distance(__middle, __second_cut);
       }
       else {
 	__len22 = __len2 / 2;
 	advance(__second_cut, __len22);
 	__first_cut = upper_bound(__first, __middle, *__second_cut, __comp);
 	__len11 = distance(__first, __first_cut);
       }
       rotate(__first_cut, __middle, __second_cut);
       _BidirectionalIter __new_middle = __first_cut;
       advance(__new_middle, distance(__middle, __second_cut));
       __merge_without_buffer(__first, __first_cut, __new_middle,
 			     __len11, __len22, __comp);
       __merge_without_buffer(__new_middle, __second_cut, __last,
 			     __len1 - __len11, __len2 - __len22, __comp);
     }

   template<typename _BidirectionalIter1, typename _BidirectionalIter2,
 	   typename _Distance>
     _BidirectionalIter1
     __rotate_adaptive(_BidirectionalIter1 __first,
 		      _BidirectionalIter1 __middle,
 		      _BidirectionalIter1 __last,
 		      _Distance __len1, _Distance __len2,
 		      _BidirectionalIter2 __buffer,
 		      _Distance __buffer_size)
     {
       _BidirectionalIter2 __buffer_end;
       if (__len1 > __len2 && __len2 <= __buffer_size) {
 	__buffer_end = copy(__middle, __last, __buffer);
 	copy_backward(__first, __middle, __last);
 	return copy(__buffer, __buffer_end, __first);
       }
       else if (__len1 <= __buffer_size) {
 	__buffer_end = copy(__first, __middle, __buffer);
 	copy(__middle, __last, __first);
 	return copy_backward(__buffer, __buffer_end, __last);
       }
       else {
 	rotate(__first, __middle, __last);
 	advance(__first, distance(__middle, __last));
 	return __first;
       }
     }

   template<typename _BidirectionalIter1, typename _BidirectionalIter2,
 	   typename _BidirectionalIter3>
     _BidirectionalIter3
     __merge_backward(_BidirectionalIter1 __first1, _BidirectionalIter1 __last1,
 		     _BidirectionalIter2 __first2, _BidirectionalIter2 __last2,
 		     _BidirectionalIter3 __result)
     {
       if (__first1 == __last1)
 	return copy_backward(__first2, __last2, __result);
       if (__first2 == __last2)
 	return copy_backward(__first1, __last1, __result);
       --__last1;
       --__last2;
       while (true) {
 	if (*__last2 < *__last1) {
 	  *--__result = *__last1;
 	  if (__first1 == __last1)
 	    return copy_backward(__first2, ++__last2, __result);
 	  --__last1;
 	}
 	else {
 	  *--__result = *__last2;
 	  if (__first2 == __last2)
 	    return copy_backward(__first1, ++__last1, __result);
 	  --__last2;
 	}
       }
     }

   template<typename _BidirectionalIter1, typename _BidirectionalIter2,
 	   typename _BidirectionalIter3, typename _Compare>
     _BidirectionalIter3
     __merge_backward(_BidirectionalIter1 __first1, _BidirectionalIter1 __last1,
 		     _BidirectionalIter2 __first2, _BidirectionalIter2 __last2,
 		     _BidirectionalIter3 __result,
 		     _Compare __comp)
     {
       if (__first1 == __last1)
 	return copy_backward(__first2, __last2, __result);
       if (__first2 == __last2)
 	return copy_backward(__first1, __last1, __result);
       --__last1;
       --__last2;
       while (true) {
 	if (__comp(*__last2, *__last1)) {
 	  *--__result = *__last1;
 	  if (__first1 == __last1)
 	    return copy_backward(__first2, ++__last2, __result);
 	  --__last1;
 	}
 	else {
 	  *--__result = *__last2;
 	  if (__first2 == __last2)
 	    return copy_backward(__first1, ++__last1, __result);
 	  --__last2;
 	}
       }
     }

   template<typename _BidirectionalIter, typename _Distance, typename _Pointer>
     void
     __merge_adaptive(_BidirectionalIter __first,
                      _BidirectionalIter __middle,
 		     _BidirectionalIter __last,
 		     _Distance __len1, _Distance __len2,
 		     _Pointer __buffer, _Distance __buffer_size)
     {
 	  if (__len1 <= __len2 && __len1 <= __buffer_size) {
 	    _Pointer __buffer_end = copy(__first, __middle, __buffer);
 	    merge(__buffer, __buffer_end, __middle, __last, __first);
 	  }
 	  else if (__len2 <= __buffer_size) {
 	    _Pointer __buffer_end = copy(__middle, __last, __buffer);
 	    __merge_backward(__first, __middle, __buffer, __buffer_end, __last);
 	  }
 	  else {
 	    _BidirectionalIter __first_cut = __first;
 	    _BidirectionalIter __second_cut = __middle;
 	    _Distance __len11 = 0;
 	    _Distance __len22 = 0;
 	    if (__len1 > __len2) {
 		  __len11 = __len1 / 2;
 		  advance(__first_cut, __len11);
 		  __second_cut = lower_bound(__middle, __last, *__first_cut);
 		  __len22 = distance(__middle, __second_cut);
 	    }
 	    else {
 		  __len22 = __len2 / 2;
 		  advance(__second_cut, __len22);
 		  __first_cut = upper_bound(__first, __middle, *__second_cut);
 		  __len11 = distance(__first, __first_cut);
 	    }
 	    _BidirectionalIter __new_middle =
 		  __rotate_adaptive(__first_cut, __middle, __second_cut,
 				    __len1 - __len11, __len22, __buffer,
 				    __buffer_size);
 	    __merge_adaptive(__first, __first_cut, __new_middle, __len11,
 			     __len22, __buffer, __buffer_size);
 	    __merge_adaptive(__new_middle, __second_cut, __last, __len1 - __len11,
 			     __len2 - __len22, __buffer, __buffer_size);
 	  }
     }

   template<typename _BidirectionalIter, typename _Distance, typename _Pointer,
 	   typename _Compare>
     void
     __merge_adaptive(_BidirectionalIter __first,
                      _BidirectionalIter __middle,
 		     _BidirectionalIter __last,
 		     _Distance __len1, _Distance __len2,
 		     _Pointer __buffer, _Distance __buffer_size,
 		     _Compare __comp)
     {
 	  if (__len1 <= __len2 && __len1 <= __buffer_size) {
 	    _Pointer __buffer_end = copy(__first, __middle, __buffer);
 	    merge(__buffer, __buffer_end, __middle, __last, __first, __comp);
 	  }
 	  else if (__len2 <= __buffer_size) {
 	    _Pointer __buffer_end = copy(__middle, __last, __buffer);
 	    __merge_backward(__first, __middle, __buffer, __buffer_end, __last,
 					     __comp);
 	  }
 	  else {
 	    _BidirectionalIter __first_cut = __first;
 	    _BidirectionalIter __second_cut = __middle;
 	    _Distance __len11 = 0;
 	    _Distance __len22 = 0;
 	    if (__len1 > __len2) {
 		  __len11 = __len1 / 2;
 		  advance(__first_cut, __len11);
 		  __second_cut = lower_bound(__middle, __last, *__first_cut, __comp);
 		  __len22 = distance(__middle, __second_cut);
 	    }
 	    else {
 		  __len22 = __len2 / 2;
 		  advance(__second_cut, __len22);
 		  __first_cut = upper_bound(__first, __middle, *__second_cut, __comp);
 		  __len11 = distance(__first, __first_cut);
 	    }
 	    _BidirectionalIter __new_middle =
 		  __rotate_adaptive(__first_cut, __middle, __second_cut,
 				    __len1 - __len11, __len22, __buffer,
 				    __buffer_size);
 	    __merge_adaptive(__first, __first_cut, __new_middle, __len11,
 			     __len22, __buffer, __buffer_size, __comp);
 	    __merge_adaptive(__new_middle, __second_cut, __last, __len1 - __len11,
 			     __len2 - __len22, __buffer, __buffer_size, __comp);
 	  }
     }

   template<typename _BidirectionalIter>
     void
     inplace_merge(_BidirectionalIter __first,
 		  _BidirectionalIter __middle,
 		  _BidirectionalIter __last)
     {
       typedef typename iterator_traits<_BidirectionalIter>::value_type
           _ValueType;
       typedef typename iterator_traits<_BidirectionalIter>::difference_type
           _DistanceType;

       // concept requirements
       __glibcpp_function_requires(_Mutable_BidirectionalIteratorConcept<
 	    _BidirectionalIter>)
       __glibcpp_function_requires(_LessThanComparableConcept<_ValueType>)

       if (__first == __middle || __middle == __last)
 	return;

       _DistanceType __len1 = distance(__first, __middle);
       _DistanceType __len2 = distance(__middle, __last);

       _Temporary_buffer<_BidirectionalIter, _ValueType> __buf(__first, __last);
       if (__buf.begin() == 0)
 	__merge_without_buffer(__first, __middle, __last, __len1, __len2);
       else
 	__merge_adaptive(__first, __middle, __last, __len1, __len2,
 			 __buf.begin(), _DistanceType(__buf.size()));
     }

   template<typename _BidirectionalIter, typename _Compare>
     void
     inplace_merge(_BidirectionalIter __first,
 		  _BidirectionalIter __middle,
 		  _BidirectionalIter __last,
 		  _Compare __comp)
     {
       typedef typename iterator_traits<_BidirectionalIter>::value_type
           _ValueType;
       typedef typename iterator_traits<_BidirectionalIter>::difference_type
           _DistanceType;

       // concept requirements
       __glibcpp_function_requires(_Mutable_BidirectionalIteratorConcept<
 	    _BidirectionalIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 	    _ValueType, _ValueType>)

       if (__first == __middle || __middle == __last)
 	return;

       _DistanceType __len1 = distance(__first, __middle);
       _DistanceType __len2 = distance(__middle, __last);

       _Temporary_buffer<_BidirectionalIter, _ValueType> __buf(__first, __last);
       if (__buf.begin() == 0)
 	__merge_without_buffer(__first, __middle, __last, __len1, __len2, __comp);
       else
 	__merge_adaptive(__first, __middle, __last, __len1, __len2,
 			 __buf.begin(), _DistanceType(__buf.size()),
 			 __comp);
     }

   // Set algorithms: includes, set_union, set_intersection, set_difference,
   // set_symmetric_difference.  All of these algorithms have the precondition
   // that their input ranges are sorted and the postcondition that their output
   // ranges are sorted.

   template<typename _InputIter1, typename _InputIter2>
     bool
     includes(_InputIter1 __first1, _InputIter1 __last1,
 	     _InputIter2 __first2, _InputIter2 __last2)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
       __glibcpp_function_requires(_SameTypeConcept<
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)
       __glibcpp_function_requires(_LessThanComparableConcept<
 	    typename iterator_traits<_InputIter1>::value_type>)

       while (__first1 != __last1 && __first2 != __last2)
 	if (*__first2 < *__first1)
 	  return false;
 	else if(*__first1 < *__first2)
 	  ++__first1;
 	else
 	  ++__first1, ++__first2;

       return __first2 == __last2;
     }

   template<typename _InputIter1, typename _InputIter2, typename _Compare>
     bool
     includes(_InputIter1 __first1, _InputIter1 __last1,
 	     _InputIter2 __first2, _InputIter2 __last2, _Compare __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
       __glibcpp_function_requires(_SameTypeConcept<
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)

       while (__first1 != __last1 && __first2 != __last2)
 	if (__comp(*__first2, *__first1))
 	  return false;
 	else if(__comp(*__first1, *__first2))
 	  ++__first1;
 	else
 	  ++__first1, ++__first2;

       return __first2 == __last2;
     }

   template<typename _InputIter1, typename _InputIter2, typename _OutputIter>
     _OutputIter
     set_union(_InputIter1 __first1, _InputIter1 __last1,
 	      _InputIter2 __first2, _InputIter2 __last2,
 	      _OutputIter __result)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter1>::value_type>)
       __glibcpp_function_requires(_SameTypeConcept<
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)
       __glibcpp_function_requires(_LessThanComparableConcept<
 	    typename iterator_traits<_InputIter1>::value_type>)

       while (__first1 != __last1 && __first2 != __last2) {
 	if (*__first1 < *__first2) {
 	  *__result = *__first1;
 	  ++__first1;
 	}
 	else if (*__first2 < *__first1) {
 	  *__result = *__first2;
 	  ++__first2;
 	}
 	else {
 	  *__result = *__first1;
 	  ++__first1;
 	  ++__first2;
 	}
 	++__result;
       }
       return copy(__first2, __last2, copy(__first1, __last1, __result));
     }

   template<typename _InputIter1, typename _InputIter2, typename _OutputIter,
 	   typename _Compare>
     _OutputIter
     set_union(_InputIter1 __first1, _InputIter1 __last1,
 	      _InputIter2 __first2, _InputIter2 __last2,
 	      _OutputIter __result, _Compare __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
       __glibcpp_function_requires(_SameTypeConcept<
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter1>::value_type>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)

       while (__first1 != __last1 && __first2 != __last2) {
 	if (__comp(*__first1, *__first2)) {
 	  *__result = *__first1;
 	  ++__first1;
 	}
 	else if (__comp(*__first2, *__first1)) {
 	  *__result = *__first2;
 	  ++__first2;
 	}
 	else {
 	  *__result = *__first1;
 	  ++__first1;
 	  ++__first2;
 	}
 	++__result;
       }
       return copy(__first2, __last2, copy(__first1, __last1, __result));
     }

   template<typename _InputIter1, typename _InputIter2, typename _OutputIter>
     _OutputIter
     set_intersection(_InputIter1 __first1, _InputIter1 __last1,
 		     _InputIter2 __first2, _InputIter2 __last2,
 		     _OutputIter __result)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter1>::value_type>)
       __glibcpp_function_requires(_SameTypeConcept<
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)
       __glibcpp_function_requires(_LessThanComparableConcept<
 	    typename iterator_traits<_InputIter1>::value_type>)

       while (__first1 != __last1 && __first2 != __last2)
 	if (*__first1 < *__first2)
 	  ++__first1;
 	else if (*__first2 < *__first1)
 	  ++__first2;
 	else {
 	  *__result = *__first1;
 	  ++__first1;
 	  ++__first2;
 	  ++__result;
 	}
       return __result;
     }

   template<typename _InputIter1, typename _InputIter2, typename _OutputIter,
 	   typename _Compare>
     _OutputIter
     set_intersection(_InputIter1 __first1, _InputIter1 __last1,
 		     _InputIter2 __first2, _InputIter2 __last2,
 		     _OutputIter __result, _Compare __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
       __glibcpp_function_requires(_SameTypeConcept<
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter1>::value_type>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)

       while (__first1 != __last1 && __first2 != __last2)
 	if (__comp(*__first1, *__first2))
 	  ++__first1;
 	else if (__comp(*__first2, *__first1))
 	  ++__first2;
 	else {
 	  *__result = *__first1;
 	  ++__first1;
 	  ++__first2;
 	  ++__result;
 	}
       return __result;
     }

   template<typename _InputIter1, typename _InputIter2, typename _OutputIter>
     _OutputIter
     set_difference(_InputIter1 __first1, _InputIter1 __last1,
 		   _InputIter2 __first2, _InputIter2 __last2,
 		   _OutputIter __result)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter1>::value_type>)
       __glibcpp_function_requires(_SameTypeConcept<
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)
       __glibcpp_function_requires(_LessThanComparableConcept<
 	    typename iterator_traits<_InputIter1>::value_type>)

       while (__first1 != __last1 && __first2 != __last2)
 	if (*__first1 < *__first2) {
 	  *__result = *__first1;
 	  ++__first1;
 	  ++__result;
 	}
 	else if (*__first2 < *__first1)
 	  ++__first2;
 	else {
 	  ++__first1;
 	  ++__first2;
 	}
       return copy(__first1, __last1, __result);
     }

   template<typename _InputIter1, typename _InputIter2, typename _OutputIter,
 	   typename _Compare>
     _OutputIter
     set_difference(_InputIter1 __first1, _InputIter1 __last1,
 		   _InputIter2 __first2, _InputIter2 __last2,
 		   _OutputIter __result, _Compare __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
       __glibcpp_function_requires(_SameTypeConcept<
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter1>::value_type>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)

       while (__first1 != __last1 && __first2 != __last2)
 	if (__comp(*__first1, *__first2)) {
 	  *__result = *__first1;
 	  ++__first1;
 	  ++__result;
 	}
 	else if (__comp(*__first2, *__first1))
 	  ++__first2;
 	else {
 	  ++__first1;
 	  ++__first2;
 	}
       return copy(__first1, __last1, __result);
     }

   template<typename _InputIter1, typename _InputIter2, typename _OutputIter>
     _OutputIter
     set_symmetric_difference(_InputIter1 __first1, _InputIter1 __last1,
 			     _InputIter2 __first2, _InputIter2 __last2,
 			     _OutputIter __result)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter1>::value_type>)
       __glibcpp_function_requires(_SameTypeConcept<
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)
       __glibcpp_function_requires(_LessThanComparableConcept<
 	    typename iterator_traits<_InputIter1>::value_type>)

       while (__first1 != __last1 && __first2 != __last2)
 	if (*__first1 < *__first2) {
 	  *__result = *__first1;
 	  ++__first1;
 	  ++__result;
 	}
 	else if (*__first2 < *__first1) {
 	  *__result = *__first2;
 	  ++__first2;
 	  ++__result;
 	}
 	else {
 	  ++__first1;
 	  ++__first2;
 	}
       return copy(__first2, __last2, copy(__first1, __last1, __result));
     }

   template<typename _InputIter1, typename _InputIter2, typename _OutputIter,
 	   typename _Compare>
     _OutputIter
     set_symmetric_difference(_InputIter1 __first1, _InputIter1 __last1,
 			     _InputIter2 __first2, _InputIter2 __last2,
 			     _OutputIter __result,
 			     _Compare __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
       __glibcpp_function_requires(_SameTypeConcept<
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)
       __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
 	    typename iterator_traits<_InputIter1>::value_type>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 	    typename iterator_traits<_InputIter1>::value_type,
 	    typename iterator_traits<_InputIter2>::value_type>)

       while (__first1 != __last1 && __first2 != __last2)
 	if (__comp(*__first1, *__first2)) {
 	  *__result = *__first1;
 	  ++__first1;
 	  ++__result;
 	}
 	else if (__comp(*__first2, *__first1)) {
 	  *__result = *__first2;
 	  ++__first2;
 	  ++__result;
 	}
 	else {
 	  ++__first1;
 	  ++__first2;
 	}
       return copy(__first2, __last2, copy(__first1, __last1, __result));
     }

   // min_element and max_element, with and without an explicitly supplied
   // comparison function.

   template<typename _ForwardIter>
     _ForwardIter
     max_element(_ForwardIter __first, _ForwardIter __last)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_LessThanComparableConcept<
 	    typename iterator_traits<_ForwardIter>::value_type>)

       if (__first == __last) return __first;
       _ForwardIter __result = __first;
       while (++__first != __last)
 	if (*__result < *__first)
 	  __result = __first;
       return __result;
     }

   template<typename _ForwardIter, typename _Compare>
     _ForwardIter
     max_element(_ForwardIter __first, _ForwardIter __last,
 		_Compare __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 	    typename iterator_traits<_ForwardIter>::value_type,
 	    typename iterator_traits<_ForwardIter>::value_type>)

       if (__first == __last) return __first;
       _ForwardIter __result = __first;
       while (++__first != __last)
 	if (__comp(*__result, *__first)) __result = __first;
       return __result;
     }

   template<typename _ForwardIter>
     _ForwardIter
     min_element(_ForwardIter __first, _ForwardIter __last)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_LessThanComparableConcept<
 	    typename iterator_traits<_ForwardIter>::value_type>)

       if (__first == __last) return __first;
       _ForwardIter __result = __first;
       while (++__first != __last)
 	if (*__first < *__result)
 	  __result = __first;
       return __result;
     }

   template<typename _ForwardIter, typename _Compare>
     _ForwardIter
     min_element(_ForwardIter __first, _ForwardIter __last,
 		_Compare __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 	    typename iterator_traits<_ForwardIter>::value_type,
 	    typename iterator_traits<_ForwardIter>::value_type>)

       if (__first == __last) return __first;
       _ForwardIter __result = __first;
       while (++__first != __last)
 	if (__comp(*__first, *__result))
 	  __result = __first;
       return __result;
     }

   // next_permutation and prev_permutation, with and without an explicitly
   // supplied comparison function.

   template<typename _BidirectionalIter>
     bool
     next_permutation(_BidirectionalIter __first, _BidirectionalIter __last)
     {
       // concept requirements
       __glibcpp_function_requires(_BidirectionalIteratorConcept<_BidirectionalIter>)
       __glibcpp_function_requires(_LessThanComparableConcept<
 	    typename iterator_traits<_BidirectionalIter>::value_type>)

       if (__first == __last)
 	return false;
       _BidirectionalIter __i = __first;
       ++__i;
       if (__i == __last)
 	return false;
       __i = __last;
       --__i;

       for(;;) {
 	_BidirectionalIter __ii = __i;
 	--__i;
 	if (*__i < *__ii) {
 	  _BidirectionalIter __j = __last;
 	  while (!(*__i < *--__j))
 	    {}
 	  iter_swap(__i, __j);
 	  reverse(__ii, __last);
 	  return true;
 	}
 	if (__i == __first) {
 	  reverse(__first, __last);
 	  return false;
 	}
       }
     }

   template<typename _BidirectionalIter, typename _Compare>
     bool
     next_permutation(_BidirectionalIter __first, _BidirectionalIter __last,
 		     _Compare __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_BidirectionalIteratorConcept<_BidirectionalIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 	    typename iterator_traits<_BidirectionalIter>::value_type,
 	    typename iterator_traits<_BidirectionalIter>::value_type>)

       if (__first == __last)
 	return false;
       _BidirectionalIter __i = __first;
       ++__i;
       if (__i == __last)
 	return false;
       __i = __last;
       --__i;

       for(;;) {
 	_BidirectionalIter __ii = __i;
 	--__i;
 	if (__comp(*__i, *__ii)) {
 	  _BidirectionalIter __j = __last;
 	  while (!__comp(*__i, *--__j))
 	    {}
 	  iter_swap(__i, __j);
 	  reverse(__ii, __last);
 	  return true;
 	}
 	if (__i == __first) {
 	  reverse(__first, __last);
 	  return false;
 	}
       }
     }

   template<typename _BidirectionalIter>
     bool
     prev_permutation(_BidirectionalIter __first, _BidirectionalIter __last)
     {
       // concept requirements
       __glibcpp_function_requires(_BidirectionalIteratorConcept<_BidirectionalIter>)
       __glibcpp_function_requires(_LessThanComparableConcept<
 	    typename iterator_traits<_BidirectionalIter>::value_type>)

       if (__first == __last)
 	return false;
       _BidirectionalIter __i = __first;
       ++__i;
       if (__i == __last)
 	return false;
       __i = __last;
       --__i;

       for(;;) {
 	_BidirectionalIter __ii = __i;
 	--__i;
 	if (*__ii < *__i) {
 	  _BidirectionalIter __j = __last;
 	  while (!(*--__j < *__i))
 	    {}
 	  iter_swap(__i, __j);
 	  reverse(__ii, __last);
 	  return true;
 	}
 	if (__i == __first) {
 	  reverse(__first, __last);
 	  return false;
 	}
       }
     }

   template<typename _BidirectionalIter, typename _Compare>
     bool
     prev_permutation(_BidirectionalIter __first, _BidirectionalIter __last,
 		     _Compare __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_BidirectionalIteratorConcept<_BidirectionalIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_Compare,
 	    typename iterator_traits<_BidirectionalIter>::value_type,
 	    typename iterator_traits<_BidirectionalIter>::value_type>)

       if (__first == __last)
 	return false;
       _BidirectionalIter __i = __first;
       ++__i;
       if (__i == __last)
 	return false;
       __i = __last;
       --__i;

       for(;;) {
 	_BidirectionalIter __ii = __i;
 	--__i;
 	if (__comp(*__ii, *__i)) {
 	  _BidirectionalIter __j = __last;
 	  while (!__comp(*--__j, *__i))
 	    {}
 	  iter_swap(__i, __j);
 	  reverse(__ii, __last);
 	  return true;
 	}
 	if (__i == __first) {
 	  reverse(__first, __last);
 	  return false;
 	}
       }
     }

   // find_first_of, with and without an explicitly supplied comparison function.

   template<typename _InputIter, typename _ForwardIter>
     _InputIter
     find_first_of(_InputIter __first1, _InputIter __last1,
 		  _ForwardIter __first2, _ForwardIter __last2)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_EqualOpConcept<
 	    typename iterator_traits<_InputIter>::value_type,
 	    typename iterator_traits<_ForwardIter>::value_type>)

       for ( ; __first1 != __last1; ++__first1)
 	for (_ForwardIter __iter = __first2; __iter != __last2; ++__iter)
 	  if (*__first1 == *__iter)
 	    return __first1;
       return __last1;
     }

   template<typename _InputIter, typename _ForwardIter, typename _BinaryPredicate>
     _InputIter
     find_first_of(_InputIter __first1, _InputIter __last1,
 		  _ForwardIter __first2, _ForwardIter __last2,
 		  _BinaryPredicate __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_EqualOpConcept<
 	    typename iterator_traits<_InputIter>::value_type,
 	    typename iterator_traits<_ForwardIter>::value_type>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
 	    typename iterator_traits<_InputIter>::value_type,
 	    typename iterator_traits<_ForwardIter>::value_type>)

       for ( ; __first1 != __last1; ++__first1)
 	for (_ForwardIter __iter = __first2; __iter != __last2; ++__iter)
 	  if (__comp(*__first1, *__iter))
 	    return __first1;
       return __last1;
     }


   // find_end, with and without an explicitly supplied comparison function.
   // Search [first2, last2) as a subsequence in [first1, last1), and return
   // the *last* possible match.  Note that find_end for bidirectional iterators
   // is much faster than for forward iterators.

   // find_end for forward iterators.
   template<typename _ForwardIter1, typename _ForwardIter2>
     _ForwardIter1
     __find_end(_ForwardIter1 __first1, _ForwardIter1 __last1,
 	       _ForwardIter2 __first2, _ForwardIter2 __last2,
 	       forward_iterator_tag, forward_iterator_tag)
     {
       if (__first2 == __last2)
 	return __last1;
       else {
 	_ForwardIter1 __result = __last1;
 	while (1) {
 	  _ForwardIter1 __new_result
 	    = search(__first1, __last1, __first2, __last2);
 	  if (__new_result == __last1)
 	    return __result;
 	  else {
 	    __result = __new_result;
 	    __first1 = __new_result;
 	    ++__first1;
 	  }
 	}
       }
     }

   template<typename _ForwardIter1, typename _ForwardIter2,
 	   typename _BinaryPredicate>
     _ForwardIter1
     __find_end(_ForwardIter1 __first1, _ForwardIter1 __last1,
 	       _ForwardIter2 __first2, _ForwardIter2 __last2,
 	       forward_iterator_tag, forward_iterator_tag,
 	       _BinaryPredicate __comp)
     {
       if (__first2 == __last2)
 	return __last1;
       else {
 	_ForwardIter1 __result = __last1;
 	while (1) {
 	  _ForwardIter1 __new_result
 	    = search(__first1, __last1, __first2, __last2, __comp);
 	  if (__new_result == __last1)
 	    return __result;
 	  else {
 	    __result = __new_result;
 	    __first1 = __new_result;
 	    ++__first1;
 	  }
 	}
       }
     }

   // find_end for bidirectional iterators.  Requires partial specialization.
   template<typename _BidirectionalIter1, typename _BidirectionalIter2>
     _BidirectionalIter1
     __find_end(_BidirectionalIter1 __first1, _BidirectionalIter1 __last1,
 	       _BidirectionalIter2 __first2, _BidirectionalIter2 __last2,
 	       bidirectional_iterator_tag, bidirectional_iterator_tag)
     {
       // concept requirements
       __glibcpp_function_requires(_BidirectionalIteratorConcept<_BidirectionalIter1>)
       __glibcpp_function_requires(_BidirectionalIteratorConcept<_BidirectionalIter2>)

       typedef reverse_iterator<_BidirectionalIter1> _RevIter1;
       typedef reverse_iterator<_BidirectionalIter2> _RevIter2;

       _RevIter1 __rlast1(__first1);
       _RevIter2 __rlast2(__first2);
       _RevIter1 __rresult = search(_RevIter1(__last1), __rlast1,
 				   _RevIter2(__last2), __rlast2);

       if (__rresult == __rlast1)
 	return __last1;
       else {
 	_BidirectionalIter1 __result = __rresult.base();
 	advance(__result, -distance(__first2, __last2));
 	return __result;
       }
     }

   template<typename _BidirectionalIter1, typename _BidirectionalIter2,
 	   typename _BinaryPredicate>
     _BidirectionalIter1
     __find_end(_BidirectionalIter1 __first1, _BidirectionalIter1 __last1,
 	       _BidirectionalIter2 __first2, _BidirectionalIter2 __last2,
 	       bidirectional_iterator_tag, bidirectional_iterator_tag,
 	       _BinaryPredicate __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_BidirectionalIteratorConcept<_BidirectionalIter1>)
       __glibcpp_function_requires(_BidirectionalIteratorConcept<_BidirectionalIter2>)

       typedef reverse_iterator<_BidirectionalIter1> _RevIter1;
       typedef reverse_iterator<_BidirectionalIter2> _RevIter2;

       _RevIter1 __rlast1(__first1);
       _RevIter2 __rlast2(__first2);
       _RevIter1 __rresult = search(_RevIter1(__last1), __rlast1,
 				   _RevIter2(__last2), __rlast2,
 				   __comp);

       if (__rresult == __rlast1)
 	return __last1;
       else {
 	_BidirectionalIter1 __result = __rresult.base();
 	advance(__result, -distance(__first2, __last2));
 	return __result;
       }
     }

   // Dispatching functions for find_end.

   template<typename _ForwardIter1, typename _ForwardIter2>
     inline _ForwardIter1
     find_end(_ForwardIter1 __first1, _ForwardIter1 __last1,
 	     _ForwardIter2 __first2, _ForwardIter2 __last2)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter1>)
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter2>)
       __glibcpp_function_requires(_EqualOpConcept<
 	    typename iterator_traits<_ForwardIter1>::value_type,
 	    typename iterator_traits<_ForwardIter2>::value_type>)

       return __find_end(__first1, __last1, __first2, __last2,
 			__iterator_category(__first1),
 			__iterator_category(__first2));
     }

   template<typename _ForwardIter1, typename _ForwardIter2,
 	   typename _BinaryPredicate>
     inline _ForwardIter1
     find_end(_ForwardIter1 __first1, _ForwardIter1 __last1,
 	     _ForwardIter2 __first2, _ForwardIter2 __last2,
 	     _BinaryPredicate __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter1>)
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter2>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
 	    typename iterator_traits<_ForwardIter1>::value_type,
 	    typename iterator_traits<_ForwardIter2>::value_type>)

       return __find_end(__first1, __last1, __first2, __last2,
 			__iterator_category(__first1),
 			__iterator_category(__first2),
 			__comp);
     }

   // is_heap, a predicate testing whether or not a range is
   // a heap.  This function is an extension, not part of the C++
   // standard.

   template<typename _RandomAccessIter, typename _Distance>
     bool
     __is_heap(_RandomAccessIter __first, _Distance __n)
     {
       _Distance __parent = 0;
       for (_Distance __child = 1; __child < __n; ++__child) {
 	if (__first[__parent] < __first[__child])
 	  return false;
 	if ((__child & 1) == 0)
 	  ++__parent;
       }
       return true;
     }

   template<typename _RandomAccessIter, typename _Distance,
            typename _StrictWeakOrdering>
     bool
     __is_heap(_RandomAccessIter __first, _StrictWeakOrdering __comp,
 	      _Distance __n)
     {
       _Distance __parent = 0;
       for (_Distance __child = 1; __child < __n; ++__child) {
 	if (__comp(__first[__parent], __first[__child]))
 	  return false;
 	if ((__child & 1) == 0)
 	  ++__parent;
       }
       return true;
     }

   template<typename _RandomAccessIter>
     inline bool
     is_heap(_RandomAccessIter __first, _RandomAccessIter __last)
     {
       // concept requirements
       __glibcpp_function_requires(_RandomAccessIteratorConcept<_RandomAccessIter>)
       __glibcpp_function_requires(_LessThanComparableConcept<
 	    typename iterator_traits<_RandomAccessIter>::value_type>)

       return __is_heap(__first, __last - __first);
     }


   template<typename _RandomAccessIter, typename _StrictWeakOrdering>
     inline bool
     is_heap(_RandomAccessIter __first, _RandomAccessIter __last,
 	    _StrictWeakOrdering __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_RandomAccessIteratorConcept<_RandomAccessIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering,
 	    typename iterator_traits<_RandomAccessIter>::value_type,
 	    typename iterator_traits<_RandomAccessIter>::value_type>)

       return __is_heap(__first, __comp, __last - __first);
     }

   // is_sorted, a predicated testing whether a range is sorted in
   // nondescending order.  This is an extension, not part of the C++
   // standard.

   template<typename _ForwardIter>
     bool
     is_sorted(_ForwardIter __first, _ForwardIter __last)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_LessThanComparableConcept<
 	    typename iterator_traits<_ForwardIter>::value_type>)

       if (__first == __last)
 	return true;

       _ForwardIter __next = __first;
       for (++__next; __next != __last; __first = __next, ++__next) {
 	if (*__next < *__first)
 	  return false;
       }

       return true;
     }

   template<typename _ForwardIter, typename _StrictWeakOrdering>
     bool
     is_sorted(_ForwardIter __first, _ForwardIter __last, _StrictWeakOrdering __comp)
     {
       // concept requirements
       __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
       __glibcpp_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering,
 	    typename iterator_traits<_ForwardIter>::value_type,
 	    typename iterator_traits<_ForwardIter>::value_type>)

       if (__first == __last)
 	return true;

       _ForwardIter __next = __first;
       for (++__next; __next != __last; __first = __next, ++__next) {
 	if (__comp(*__next, *__first))
 	  return false;
       }

       return true;
     }

 } // namespace std

 #endif /* __GLIBCPP_INTERNAL_ALGO_H */

 // Local Variables:
 // mode:C++
 // End: