/**
 * Echoes the value returned by \wpml_the_language_input_field
 *
 * @since 3.1.7.3
 */
function wpml_the_language_input_field()
{
    echo wpml_get_language_input_field();
}

 /**
  * Filter to add language field to WordPress search form
  * 
  * @param string $form HTML code of search for before filtering
  * @return string HTML code of search form
  */
 function get_search_form_filter($form)
 {
     if (strpos($form, wpml_get_language_input_field()) === false) {
         $form = str_replace("</form>", wpml_get_language_input_field() . "</form>", $form);
     }
     return $form;
 }

 /**
  * Filter to add language field to WordPress search form
  *
  * @param string $form HTML code of search for before filtering
  * @return string HTML code of search form
  */
 function get_search_form_filter($form)
 {
     if (strpos($form, wpml_get_language_input_field()) === false && WPML_LANGUAGE_NEGOTIATION_TYPE_PARAMETER === (int) $this->get_setting('language_negotiation_type')) {
         $form = str_replace("</form>", wpml_get_language_input_field() . "</form>", $form);
     }
     return $form;
 }