public function evaluate($values)
    {
        // Only validate if the source is set to 'list'
        $sourceElement = $this->getOption('sourceElement');
        $sourceElementValue = $sourceElement->getEvaluatedValue();
        if ($sourceElementValue !== 'list') {
            return true;
        }

        $this->invalidValues = [];
        $values = trim(str_replace("\r", '', $values));

        if (!$values) {
            $this->setMessage('Please add at least one domain or directive.');
            return false;
        }

        $sources = explode("\n", $values);

        foreach ($sources as $key => $source) {
            if ($source === '') {
                unset($sources[$key]);
            }

            if (in_array($source, self::DIRECTIVES, true)) {
                if ($this->isValidDirective($source) === false) {
                    $this->invalidValues['domain'][] = $source;
                }
                $sources[$key] = $this->getNormalizedDirective($source);

                continue;
            }

            if ($this->isValidDomain($source) === false) {
                $this->invalidValues['domain'][] = $source;
            }
        }

        $isValid = empty($this->invalidValues);
        if (!$isValid) {
            $this->setMessage($this->getErrorMessage());
        }

        return $isValid;
    }