Attribute::createAttributeValue

protected Attribute::createAttributeValue($name, $value)

protected function createAttributeValue($name, $value) {
  // If the value is already an AttributeValueBase object,
  // return a new instance of the same class, but with the new name.
  if ($value instanceof AttributeValueBase) {
    $class = get_class($value);
    return new $class($name, $value->value());
  }
  // An array value or 'class' attribute name are forced to always be an
  // AttributeArray value for consistency.
  if ($name == 'class' && !is_array($value)) {
    // Cast the value to string in case it implements MarkupInterface.
    $value = [(string) $value];
  }
  if (is_array($value)) {
    // Cast the value to an array if the value was passed in as a string.
    // @todo Decide to fix all the broken instances of class as a string
    // in core or cast them.
    $value = new AttributeArray($name, $value);
  }
  elseif (is_bool($value)) {
    $value = new AttributeBoolean($name, $value);
  }
  // As a development aid, we allow the value to be a safe string object.
  elseif ($value instanceof MarkupInterface) {
    // Attributes are not supposed to display HTML markup, so we just convert
    // the value to plain text.
    $value = PlainTextOutput::renderFromHtml($value);
    $value = new AttributeString($name, $value);
  }
  elseif (!is_object($value)) {
    $value = new AttributeString($name, $value);
  }
  return $value;
}