Goetas\Twital\Helper\ParserHelper::staticSplitExpression PHP Method

    public static function staticSplitExpression($str, $splitter, $limit = 0)
    {
        $in = array();
        $inApex = false;
        $parts = array();
        $prev = 0;
        for ($i = 0, $l = strlen($str); $i < $l; $i++) {
            $chr = $str[$i];
            if ($chr == "'" || $chr == '"') {
                $j = 1;
                while ($i >= $j && $str[$i - $j] === '\\') {
                    $j++;
                }
                if ($j % 2 !== 0) {
                    if (!$inApex) {
                        $inApex = $chr;
                    } elseif ($inApex === $chr) {
                        $inApex = false;
                    }
                }
            }
            if (!$inApex) {
                if (in_array($chr, self::$closing)) {
                    array_push($in, $chr);
                } elseif (isset(self::$closing[$chr]) && self::$closing[$chr] === end($in)) {
                    array_pop($in);
                } elseif (isset(self::$closing[$chr]) && !count($in)) {
                    throw new Exception(sprintf('Unexpected "%s" next to "%s"', $chr, substr($str, 0, $i + 1)));
                }
                if (!count($in) && $chr === $splitter) {
                    $parts[] = substr($str, $prev, $i - $prev);
                    $prev = $i + 1;
                    if ($limit > 1 && count($parts) == $limit - 1) {
                        break;
                    }
                }
            }
        }
        if ($inApex) {
            throw new Exception(sprintf('Can\'t find the closing "%s" in "%s" expression', $inApex, $str));
        } elseif (count($in)) {
            throw new Exception(sprintf('Can\'t find the closing braces for "%s" in "%s" expression', implode(',', $in), $str));
        }
        $parts[] = substr($str, $prev);
        return array_map('trim', $parts);
    }

 public function visit(\DOMAttr $att, Compiler $context)
 {
     $node = $att->ownerElement;
     $sets = ParserHelper::staticSplitExpression(html_entity_decode($att->value), ",");
     foreach ($sets as $set) {
         $pi = $context->createControlNode("set " . $set);
         $node->parentNode->insertBefore($pi, $node);
     }
     $node->removeAttributeNode($att);
 }