Method prepareOptionsNested

/**
 * Add "-" before nested tags, depending on level
 *
 * @param   array  &$options  Array of tags
 *
 * @return  array  The field option objects.
 *
 * @since   3.1
 */
protected function prepareOptionsNested(&$options)
{
    if ($options) {
        foreach ($options as &$option) {
            $repeat = isset($option->level) && $option->level - 1 >= 0 ? $option->level - 1 : 0;
            $option->text = str_repeat('- ', $repeat) . $option->text;
        }
    }
    return $options;
}