class MY_Router extends CI_Router {
  
    /**
     * Validates the supplied segments.  Attempts to determine the path to
     * the controller.
     *
     * @access    private
     * @param    array
     * @return    array
     */    
    function _validate_request($segments)
    {
        // Does the requested controller exist in the root folder?
        if (file_exists(APPPATH.'controllers/'.$this->fetch_directory().$segments[0].EXT))
        {
            return $segments;
        }

        // Is the controller in a sub-folder?
        if (is_dir(APPPATH.'controllers/'.$this->fetch_directory().$segments[0]))
        {        
            // Set the directory and remove it from the segment array
            $this->_append_directory($segments[0]);
            $segments = array_slice($segments, 1);
            
            if (count($segments) > 0)
            {
                // Does the requested controller exist in the sub-folder?
                if ( ! file_exists(APPPATH.'controllers/'.$this->fetch_directory().$segments[0].EXT))
                {
                    return $this->_validate_request($segments);
                }
            }
            else
            {
                $this->set_class($this->default_controller);
                $this->set_method('index');
            
                // Does the default controller exist in the sub-folder?
                if ( ! file_exists(APPPATH.'controllers/'.$this->fetch_directory().$this->default_controller.EXT))
                {
                    $this->directory = '';
                    return array();
                }
            
            }

            return $segments;
        }

        // Can't find the requested controller...
        show_404($segments[0]);
    }

    /**
     *  Append the directory name
     *
     * @access  public
     * @param   string
     * @return  void
     */ 
    function _append_directory($dir)
    {
        $this->directory .= $dir.'/';
    }
}