/** * @param ElementInterface $element * * @throws ValidationError */ public function validate(ElementInterface $element) { if ($element->isLeaf()) { if (strlen($element->getContent()) === 0) { throw new ValidationError(sprintf($this->message, 'content')); } } else { if (count($element->getChildren()) === 0) { throw new ValidationError(sprintf($this->message, 'children[]')); } } }