Sets a form element's class attribute.
Adds 'required' and 'error' classes as needed.
$element: The form element.
$name: Array of new class names to be added.
function _form_set_class(&$element, $class = array()) {
if (!empty($class)) {
if (!isset($element['#attributes']['class'])) {
$element['#attributes']['class'] = array();
}
$element['#attributes']['class'] = array_merge($element['#attributes']['class'], $class);
}
// This function is invoked from form element theme functions, but the
// rendered form element may not necessarily have been processed by
// form_builder().
if (!empty($element['#required'])) {
$element['#attributes']['class'][] = 'required';
}
if (isset($element['#parents']) && form_get_error($element) !== NULL && !empty($element['#validated'])) {
$element['#attributes']['class'][] = 'error';
}
}