BBP_Walker_Dropdown

class BBP_Walker_Dropdown extends Walker {

	/**
	 * @see Walker::$tree_type
	 *
	 * @since bbPress (r2746)
	 *
	 * @var string
	 */
	var $tree_type;

	/**
	 * @see Walker::$db_fields
	 *
	 * @since bbPress (r2746)
	 *
	 * @var array
	 */
	var $db_fields = array( 'parent' => 'post_parent', 'id' => 'ID' );

	/** Methods ***************************************************************/

	/**
	 * Set the tree_type
	 *
	 * @since bbPress (r2746)
	 */
	public function __construct() {
		$this->tree_type = bbp_get_forum_post_type();
	}

	/**
	 * @see Walker::start_el()
	 *
	 * @since bbPress (r2746)
	 *
	 * @param string $output Passed by reference. Used to append additional
	 *                        content.
	 * @param object $_post Post data object.
	 * @param int $depth Depth of post in reference to parent posts. Used
	 *                    for padding.
	 * @param array $args Uses 'selected' argument for selected post to set
	 *                     selected HTML attribute for option element.
	 * @param int $current_object_id
	 * @uses bbp_is_forum_category() To check if the forum is a category
	 * @uses current_user_can() To check if the current user can post in
	 *                           closed forums
	 * @uses bbp_is_forum_closed() To check if the forum is closed
	 * @uses apply_filters() Calls 'bbp_walker_dropdown_post_title' with the
	 *                        title, output, post, depth and args
	 */
	public function start_el( &$output, $object, $depth = 0, $args = array(), $current_object_id = 0 ) {
		$pad     = str_repeat( ' ', (int) $depth * 3 );
		$output .= '<option class="level-' . (int) $depth . '"';

		// Disable the <option> if:
		// - we're told to do so
		// - the post type is a forum
		// - the forum is a category
		// - forum is closed
		if (	( true === $args['disable_categories'] )
				&& ( bbp_get_forum_post_type() === $object->post_type )
				&& ( bbp_is_forum_category( $object->ID )
					|| ( !current_user_can( 'edit_forum', $object->ID ) && bbp_is_forum_closed( $object->ID )
				)
			) ) {
			$output .= ' disabled="disabled" value=""';
		} else {
			$output .= ' value="' . (int) $object->ID .'"' . selected( $args['selected'], $object->ID, false );
		}

		$output .= '>';
		$title   = apply_filters( 'bbp_walker_dropdown_post_title', $object->post_title, $output, $object, $depth, $args );
		$output .= $pad . esc_html( $title );
		$output .= "</option>\n";
	}
}