algorithm

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// Algorithm extensions -*- C++ -*-

// Copyright (C) 2001, 2002 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 ext/algorithm
 *  This file is a GNU extension to the Standard C++ Library (possibly
 *  containing extensions from the HP/SGI STL subset).  You should only
 *  include this header if you are using GCC 3 or later.
 */

#ifndef _EXT_ALGORITHM
#define _EXT_ALGORITHM 1

#pragma GCC system_header

#include <algorithm>

namespace __gnu_cxx
{
  using std::ptrdiff_t;
  using std::min;
  using std::pair;
  using std::input_iterator_tag;
  using std::random_access_iterator_tag;
  using std::iterator_traits;

  //--------------------------------------------------
  // copy_n (not part of the C++ standard)

  template<typename _InputIterator, typename _Size, typename _OutputIterator>
    pair<_InputIterator, _OutputIterator>
    __copy_n(_InputIterator __first, _Size __count,
	     _OutputIterator __result,
	     input_iterator_tag)
    {
      for ( ; __count > 0; --__count) {
	*__result = *__first;
	++__first;
	++__result;
      }
      return pair<_InputIterator, _OutputIterator>(__first, __result);
    }

  template<typename _RAIterator, typename _Size, typename _OutputIterator>
    inline pair<_RAIterator, _OutputIterator>
    __copy_n(_RAIterator __first, _Size __count,
	     _OutputIterator __result,
	     random_access_iterator_tag)
    {
      _RAIterator __last = __first + __count;
      return pair<_RAIterator, _OutputIterator>(__last,
					std::copy(__first, __last, __result));
    }

  /**
   *  @brief Copies the range [first,first+count) into [result,result+count).
   *  @param  first  An input iterator.
   *  @param  count  The number of elements to copy.
   *  @param  result An output iterator.
   *  @return   A std::pair composed of first+count and result+count.
   *
   *  This is an SGI extension.
   *  This inline function will boil down to a call to @c memmove whenever
   *  possible.  Failing that, if random access iterators are passed, then the
   *  loop count will be known (and therefore a candidate for compiler
   *  optimizations such as unrolling).
   *  @ingroup SGIextensions
  */
  template<typename _InputIterator, typename _Size, typename _OutputIterator>
    inline pair<_InputIterator, _OutputIterator>
    copy_n(_InputIterator __first, _Size __count, _OutputIterator __result)
    {
      // concept requirements
      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
	    typename iterator_traits<_InputIterator>::value_type>)

      return __copy_n(__first, __count, __result,
		      std::__iterator_category(__first));
    }

  template<typename _InputIterator1, typename _InputIterator2>
    int
    __lexicographical_compare_3way(_InputIterator1 __first1, _InputIterator1 __last1,
				   _InputIterator2 __first2, _InputIterator2 __last2)
    {
      while (__first1 != __last1 && __first2 != __last2) {
	if (*__first1 < *__first2)
	  return -1;
	if (*__first2 < *__first1)
	  return 1;
	++__first1;
	++__first2;
      }
      if (__first2 == __last2) {
	return !(__first1 == __last1);
      }
      else {
	return -1;
      }
    }

  inline int
  __lexicographical_compare_3way(const unsigned char* __first1,
				 const unsigned char* __last1,
				 const unsigned char* __first2,
				 const unsigned char* __last2)
  {
    const ptrdiff_t __len1 = __last1 - __first1;
    const ptrdiff_t __len2 = __last2 - __first2;
    const int __result = std::memcmp(__first1, __first2, min(__len1, __len2));
    return __result != 0 ? __result
			 : (__len1 == __len2 ? 0 : (__len1 < __len2 ? -1 : 1));
  }

  inline int
  __lexicographical_compare_3way(const char* __first1, const char* __last1,
				 const char* __first2, const char* __last2)
  {
#if CHAR_MAX == SCHAR_MAX
    return __lexicographical_compare_3way(
				  (const signed char*) __first1,
				  (const signed char*) __last1,
				  (const signed char*) __first2,
				  (const signed char*) __last2);
#else
    return __lexicographical_compare_3way((const unsigned char*) __first1,
					  (const unsigned char*) __last1,
					  (const unsigned char*) __first2,
					  (const unsigned char*) __last2);
#endif
  }

  /**
   *  @brief @c memcmp on steroids.
   *  @param  first1  An input iterator.
   *  @param  last1   An input iterator.
   *  @param  first2  An input iterator.
   *  @param  last2   An input iterator.
   *  @return   An int, as with @c memcmp.
   *
   *  The return value will be less than zero if the first range is
   *  "lexigraphically less than" the second, greater than zero if the second
   *  range is "lexigraphically less than" the first, and zero otherwise.
   *  This is an SGI extension.
   *  @ingroup SGIextensions
  */
  template<typename _InputIterator1, typename _InputIterator2>
    int
    lexicographical_compare_3way(_InputIterator1 __first1, _InputIterator1 __last1,
				 _InputIterator2 __first2, _InputIterator2 __last2)
    {
      // concept requirements
      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
      __glibcxx_function_requires(_LessThanComparableConcept<
	    typename iterator_traits<_InputIterator1>::value_type>)
      __glibcxx_function_requires(_LessThanComparableConcept<
	    typename iterator_traits<_InputIterator2>::value_type>)
      __glibcxx_requires_valid_range(__first1, __last1);
      __glibcxx_requires_valid_range(__first2, __last2);

      return __lexicographical_compare_3way(__first1, __last1, __first2, __last2);
    }

  // count and count_if: this version, whose return type is void, was present
  // in the HP STL, and is retained as an extension for backward compatibility.

  template<typename _InputIterator, typename _Tp, typename _Size>
    void
    count(_InputIterator __first, _InputIterator __last,
	  const _Tp& __value,
	  _Size& __n)
    {
      // concept requirements
      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
      __glibcxx_function_requires(_EqualityComparableConcept<
	    typename iterator_traits<_InputIterator>::value_type >)
      __glibcxx_function_requires(_EqualityComparableConcept<_Tp>)
      __glibcxx_requires_valid_range(__first, __last);

      for ( ; __first != __last; ++__first)
	if (*__first == __value)
	  ++__n;
    }

  template<typename _InputIterator, typename _Predicate, typename _Size>
    void
    count_if(_InputIterator __first, _InputIterator __last,
	     _Predicate __pred,
	     _Size& __n)
    {
      // concept requirements
      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
      __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
	    typename iterator_traits<_InputIterator>::value_type>)
      __glibcxx_requires_valid_range(__first, __last);

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

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

  /**
   *  This is an SGI extension.
   *  @ingroup SGIextensions
   *  @doctodo