DOM findElementsByClass

function _getElementsByClassName(DOMNode $node, $class)
    {
        $elements = array();

        if (XML_ELEMENT_NODE === $node->nodeType && $node->hasAttributes()) {
            for ($i = 0; $i < $node->attributes->length; $i++) {
                $attribute = $node->attributes->item($i);
                if ('class' === strtolower($attribute->name)) {
                    $values = explode(' ', $attribute->value);
                    if (in_array($class, $values)) {
                        $elements[] = $node;
                    }
                }
            }
        }

        if ($node->hasChildNodes()) {
            foreach ($node->childNodes as $childNode) {
                $elements += getElementsByClass($childNode, $class);
            }
        }

        return $elements;
    }