cleanpath_aggressive

# File ext/pathname/lib/pathname.rb, line 97
  def cleanpath_aggressive # :nodoc:
    path = @path
    names = []
    pre = path
    while r = chop_basename(pre)
      pre, base = r
      case base
      when '.'
      when '..'
        names.unshift base
      else
        if names[0] == '..'
          names.shift
        else
          names.unshift base
        end
      end
    end
    pre.tr!(File::ALT_SEPARATOR, File::SEPARATOR) if File::ALT_SEPARATOR
    if /#{SEPARATOR_PAT}/ =~ File.basename(pre)
      names.shift while names[0] == '..'
    end
    self.class.new(prepend_prefix(pre, File.join(*names)))
  end