/**
 * Implements hook_language_switch_links_alter().
 */
function {{ machine_name }}_language_switch_links_alter(array &$links, $type, $path) {
  global $language;

  if ($type == LANGUAGE_TYPE_CONTENT && isset($links[$language->language])) {
    foreach ($links[$language->language] as $link) {
      $link['attributes']['class'][] = 'active-language';
    }
  }
}