minmax_element.hpp

来自「support vector clustering for vc++」· HPP 代码 · 共 552 行 · 第 1/2 页

  template <typename ForwardIter>
  ForwardIter
  last_min_element(ForwardIter first, ForwardIter last)
  {
    return detail::basic_last_min_element(first, last,
             detail::less_over_iter<ForwardIter>() );
  }

  template <typename ForwardIter, class BinaryPredicate>
  ForwardIter
  last_min_element(ForwardIter first, ForwardIter last, BinaryPredicate comp)
  {
    return detail::basic_last_min_element(first, last,
             detail::binary_pred_over_iter<ForwardIter,BinaryPredicate>(comp) );
  }

  template <typename ForwardIter>
  ForwardIter
  first_max_element(ForwardIter first, ForwardIter last)
  {
    return detail::basic_first_max_element(first, last,
             detail::less_over_iter<ForwardIter>() );
  }

  template <typename ForwardIter, class BinaryPredicate>
  ForwardIter
  first_max_element(ForwardIter first, ForwardIter last, BinaryPredicate comp)
  {
    return detail::basic_first_max_element(first, last,
             detail::binary_pred_over_iter<ForwardIter,BinaryPredicate>(comp) );
  }

  template <typename ForwardIter>
  ForwardIter
  last_max_element(ForwardIter first, ForwardIter last)
  {
    return detail::basic_last_max_element(first, last,
             detail::less_over_iter<ForwardIter>() );
  }

  template <typename ForwardIter, class BinaryPredicate>
  ForwardIter
  last_max_element(ForwardIter first, ForwardIter last, BinaryPredicate comp)
  {
    return detail::basic_last_max_element(first, last,
             detail::binary_pred_over_iter<ForwardIter,BinaryPredicate>(comp) );
  }


  // Minmax_element variants -- comments removed

  namespace detail {

  template <typename ForwardIter, class BinaryPredicate>
  std::pair<ForwardIter,ForwardIter>
  basic_first_min_last_max_element(ForwardIter first, ForwardIter last,
                                   BinaryPredicate comp)
  {
    if (first == last)
      return std::make_pair(last,last);

    ForwardIter min_result = first;
    ForwardIter max_result = first;

    ForwardIter second = ++first;
    if (second == last)
      return std::make_pair(min_result, max_result);

    if (comp(second, min_result))
      min_result = second;
    else
      max_result = second;

    first = ++second; if (first != last) ++second;
    while (second != last) {
      if (!comp(second, first)) {
        if (comp(first, min_result))
                 min_result = first;
        if (!comp(second, max_result))
          max_result = second;
      } else {
        if (comp(second, min_result))
          min_result = second;
        if (!comp(first, max_result))
              max_result = first;
      }
      first = ++second; if (first != last) ++second;
    }

    if (first != last) {
      if (comp(first, min_result))
         min_result = first;
      else if (!comp(first, max_result))
               max_result = first;
    }

    return std::make_pair(min_result, max_result);
  }

  template <typename ForwardIter, class BinaryPredicate>
  std::pair<ForwardIter,ForwardIter>
  basic_last_min_first_max_element(ForwardIter first, ForwardIter last,
                                   BinaryPredicate comp)
  {
    if (first == last) return std::make_pair(last,last);

    ForwardIter min_result = first;
    ForwardIter max_result = first;

    ForwardIter second = ++first;
    if (second == last)
      return std::make_pair(min_result, max_result);

    if (comp(max_result, second))
      max_result = second;
    else
      min_result = second;

    first = ++second; if (first != last) ++second;
    while (second != last)  {
      if (comp(first, second)) {
        if (!comp(min_result, first))
          min_result = first;
        if (comp(max_result, second))
          max_result = second;
      } else {
        if (!comp(min_result, second))
          min_result = second;
        if (comp(max_result, first))
          max_result = first;
      }
      first = ++second; if (first != last) ++second;
    }

    if (first != last) {
      if (!comp(min_result, first))
        min_result = first;
      else if (comp(max_result, first))
        max_result = first;
    }

    return std::make_pair(min_result, max_result);
  }

  template <typename ForwardIter, class BinaryPredicate>
  std::pair<ForwardIter,ForwardIter>
  basic_last_min_last_max_element(ForwardIter first, ForwardIter last,
                                  BinaryPredicate comp)
  {
    if (first == last) return std::make_pair(last,last);

    ForwardIter min_result = first;
    ForwardIter max_result = first;

    ForwardIter second = first; ++second;
    if (second == last)
      return std::make_pair(min_result,max_result);

    ForwardIter potential_max_result = last;
    if (comp(first, second))
      max_result = second;
    else {
      min_result = second;
      potential_max_result = second;
    }

    first = ++second; if (first != last) ++second;
    while (second != last) {
      if (comp(first, second)) {
        if (!comp(min_result, first))
          min_result = first;
        if (!comp(second, max_result)) {
          max_result = second;
          potential_max_result = last;
        }
      } else {
        if (!comp(min_result, second))
          min_result = second;
        if (!comp(first, max_result)) {
          max_result = first;
          potential_max_result = second;
        }
      }
      first = ++second;
      if (first != last) ++second;
    }

    if (first != last) {
      if (!comp(min_result, first))
        min_result = first;
      if (!comp(first, max_result)) {
        max_result = first;
               potential_max_result = last;
      }
    }

    if (potential_max_result != last
        && !comp(potential_max_result, max_result))
      max_result = potential_max_result;

    return std::make_pair(min_result,max_result);
  }

  } // namespace detail

  template <typename ForwardIter>
  inline std::pair<ForwardIter,ForwardIter>
  first_min_first_max_element(ForwardIter first, ForwardIter last)
  {
    return minmax_element(first, last);
  }

  template <typename ForwardIter, class BinaryPredicate>
  inline std::pair<ForwardIter,ForwardIter>
  first_min_first_max_element(ForwardIter first, ForwardIter last,
                              BinaryPredicate comp)
  {
    return minmax_element(first, last, comp);
  }

  template <typename ForwardIter>
  std::pair<ForwardIter,ForwardIter>
  first_min_last_max_element(ForwardIter first, ForwardIter last)
  {
    return detail::basic_first_min_last_max_element(first, last,
             detail::less_over_iter<ForwardIter>() );
  }

  template <typename ForwardIter, class BinaryPredicate>
  inline std::pair<ForwardIter,ForwardIter>
  first_min_last_max_element(ForwardIter first, ForwardIter last,
                              BinaryPredicate comp)
  {
    return detail::basic_first_min_last_max_element(first, last,
             detail::binary_pred_over_iter<ForwardIter,BinaryPredicate>(comp) );
  }

  template <typename ForwardIter>
  std::pair<ForwardIter,ForwardIter>
  last_min_first_max_element(ForwardIter first, ForwardIter last)
  {
    return detail::basic_last_min_first_max_element(first, last,
             detail::less_over_iter<ForwardIter>() );
  }

  template <typename ForwardIter, class BinaryPredicate>
  inline std::pair<ForwardIter,ForwardIter>
  last_min_first_max_element(ForwardIter first, ForwardIter last,
                              BinaryPredicate comp)
  {
    return detail::basic_last_min_first_max_element(first, last,
             detail::binary_pred_over_iter<ForwardIter,BinaryPredicate>(comp) );
  }

  template <typename ForwardIter>
  std::pair<ForwardIter,ForwardIter>
  last_min_last_max_element(ForwardIter first, ForwardIter last)
  {
    return detail::basic_last_min_last_max_element(first, last,
             detail::less_over_iter<ForwardIter>() );
  }

  template <typename ForwardIter, class BinaryPredicate>
  inline std::pair<ForwardIter,ForwardIter>
  last_min_last_max_element(ForwardIter first, ForwardIter last,
                              BinaryPredicate comp)
  {
    return detail::basic_last_min_last_max_element(first, last,
             detail::binary_pred_over_iter<ForwardIter,BinaryPredicate>(comp) );
  }

} // namespace boost

#endif // BOOST_ALGORITHM_MINMAX_ELEMENT_HPP