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.
 */

#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));
    }

  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
  }

  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).

  template<typename _ForwardIterator, typename _OutputIterator, typename _Distance>
    _OutputIterator
    random_sample_n(_ForwardIterator __first, _ForwardIterator __last,
                    _OutputIterator __out, const _Distance __n)
    {
      // concept requirements
      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
        typename iterator_traits<_ForwardIterator>::value_type>)
      __glibcxx_requires_valid_range(__first, __last);

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

      while (__m > 0) {
    if ((std::rand() % __remaining) < __m) {
          *__out = *__first;
          ++__out;
          --__m;
    }

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

  template<typename _ForwardIterator, typename _OutputIterator, typename _Distance,
       typename _RandomNumberGenerator>
    _OutputIterator
    random_sample_n(_ForwardIterator __first, _ForwardIterator __last,
                   _OutputIterator __out, const _Distance __n,
           _RandomNumberGenerator& __rand)
    {
      // concept requirements
      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
        typename iterator_traits<_ForwardIterator>::value_type>)
      __glibcxx_function_requires(_UnaryFunctionConcept<
        _RandomNumberGenerator, _Distance, _Distance>)
      __glibcxx_requires_valid_range(__first, __last);

      _Distance __remaining = std::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 _InputIterator, typename _RandomAccessIterator, typename _Distance>
    _RandomAccessIterator
    __random_sample(_InputIterator __first, _InputIterator __last,
            _RandomAccessIterator __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 = std::rand() % (__t);
    if (__M < __n)
      __out[__M] = *__first;
    ++__first;
      }

      return __out + __m;
    }

  template<typename _InputIterator, typename _RandomAccessIterator,
       typename _RandomNumberGenerator, typename _Distance>
    _RandomAccessIterator
    __random_sample(_InputIterator __first, _InputIterator __last,
            _RandomAccessIterator __out,
            _RandomNumberGenerator& __rand,
            const _Distance __n)
    {
      // concept requirements
      __glibcxx_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 _InputIterator, typename _RandomAccessIterator>
    inline _RandomAccessIterator
    random_sample(_InputIterator __first, _InputIterator __last,
          _RandomAccessIterator __out_first, _RandomAccessIterator __out_last)
    {
      // concept requirements
      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
      __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
        _RandomAccessIterator>)
      __glibcxx_requires_valid_range(__first, __last);
      __glibcxx_requires_valid_range(__out_first, __out_last);

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

  template<typename _InputIterator, typename _RandomAccessIterator,
       typename _RandomNumberGenerator>
    inline _RandomAccessIterator
    random_sample(_InputIterator __first, _InputIterator __last,
          _RandomAccessIterator __out_first, _RandomAccessIterator __out_last,
          _RandomNumberGenerator& __rand)
    {
      // concept requirements
      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
      __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
        _RandomAccessIterator>)
      __glibcxx_requires_valid_range(__first, __last);
      __glibcxx_requires_valid_range(__out_first, __out_last);

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

  template<typename _RandomAccessIterator>
    inline bool
    is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
    {
      // concept requirements
      __glibcxx_function_requires(_RandomAccessIteratorConcept<_RandomAccessIterator>)
      __glibcxx_function_requires(_LessThanComparableConcept<
        typename iterator_traits<_RandomAccessIterator>::value_type>)
      __glibcxx_requires_valid_range(__first, __last);

      return std::__is_heap(__first, __last - __first);
    }

  template<typename _RandomAccessIterator, typename _StrictWeakOrdering>
    inline bool
    is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last,
        _StrictWeakOrdering __comp)
    {
      // concept requirements
      __glibcxx_function_requires(_RandomAccessIteratorConcept<_RandomAccessIterator>)
      __glibcxx_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering,
        typename iterator_traits<_RandomAccessIterator>::value_type,
        typename iterator_traits<_RandomAccessIterator>::value_type>)
      __glibcxx_requires_valid_range(__first, __last);

      return std::__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 _ForwardIterator>
    bool
    is_sorted(_ForwardIterator __first, _ForwardIterator __last)
    {
      // concept requirements
      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
      __glibcxx_function_requires(_LessThanComparableConcept<
        typename iterator_traits<_ForwardIterator>::value_type>)
      __glibcxx_requires_valid_range(__first, __last);

      if (__first == __last)
    return true;

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

      return true;
    }

  template<typename _ForwardIterator, typename _StrictWeakOrdering>
    bool
    is_sorted(_ForwardIterator __first, _ForwardIterator __last, _StrictWeakOrdering __comp)
    {
      // concept requirements
      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
      __glibcxx_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering,
        typename iterator_traits<_ForwardIterator>::value_type,
        typename iterator_traits<_ForwardIterator>::value_type>)
      __glibcxx_requires_valid_range(__first, __last);

      if (__first == __last)
    return true;

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

      return true;
    }
} // namespace __gnu_cxx

#endif /* _EXT_ALGORITHM */

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