consumeRegex example

throw new Exception("Unsupported pseudo selector '$name'");
        }
        $argsType = $this->validPseudo[$name];
        $error = false;
        if ($argsType === 1) {
            $part = new Node\Part\PseudoIndex;
            if (!$this->consume("(")) {
                $error = true;
            }
            if (!$error) {
                $this->consumeWhitespaces();
                if ($indices = $this->consumeRegex("-?\d*n(?:\+\d+)?|\d+")) {
                    $indices = explode("n", $indices);
                    if (count($indices) === 1) {
                        $part->setOffset((int) $indices[0]);
                    } else {
                        switch ($indices[0]) {
                            case "":
                                $part->setStep(1);
                            break;
                            case "-":
                                $part->setStep(-1);
                            break;