Flow\JSONPath\Filters\QueryResultFilter::filter PHP Метод

    public function filter($collection)
    {
        $result = [];
        preg_match('/@\\.(?<key>\\w+)\\s*(?<operator>-|\\+|\\*|\\/)\\s*(?<numeric>\\d+)/', $this->token->value, $matches);
        $matchKey = $matches['key'];
        if (AccessHelper::keyExists($collection, $matchKey, $this->magicIsAllowed)) {
            $value = AccessHelper::getValue($collection, $matchKey, $this->magicIsAllowed);
        } else {
            if ($matches['key'] === 'length') {
                $value = count($collection);
            } else {
                return;
            }
        }
        switch ($matches['operator']) {
            case '+':
                $resultKey = $value + $matches['numeric'];
                break;
            case '*':
                $resultKey = $value * $matches['numeric'];
                break;
            case '-':
                $resultKey = $value - $matches['numeric'];
                break;
            case '/':
                $resultKey = $value / $matches['numeric'];
                break;
            default:
                throw new JSONPathException("Unsupported operator in expression");
                break;
        }
        if (AccessHelper::keyExists($collection, $resultKey, $this->magicIsAllowed)) {
            $result[] = AccessHelper::getValue($collection, $resultKey, $this->magicIsAllowed);
        }
        return $result;
    }