PhpCss\Parser\PseudoClass::createPseudoClassPosition PHP Метод

    private function createPseudoClassPosition($string)
    {
        $string = str_replace(' ', '', $string);
        if ($string == 'n') {
            $position = new Ast\Selector\Simple\PseudoClass\Position(1, 0);
        } elseif ($string == 'odd') {
            $position = new Ast\Selector\Simple\PseudoClass\Position(2, 1);
        } elseif ($string == 'even') {
            $position = new Ast\Selector\Simple\PseudoClass\Position(2, 0);
        } elseif (preg_match('(^[+-]?\\d+$)D', $string)) {
            $position = new Ast\Selector\Simple\PseudoClass\Position(0, (int) $string);
        } elseif (preg_match('(^(?P<repeat>\\d+)n$)D', $string, $matches) || preg_match('(^(?P<repeat>[+-]?\\d*)n(?P<add>[+-]\\d+)$)D', $string, $matches)) {
            $position = new Ast\Selector\Simple\PseudoClass\Position(isset($matches['repeat']) && $matches['repeat'] != '' ? (int) $matches['repeat'] : 1, isset($matches['add']) ? (int) $matches['add'] : 0);
        } else {
            throw new \LogicException('Invalid pseudo class position - @todo implement exception');
        }
        return $position;
    }