eZ\Publish\Core\QueryType\QueryParameterContentViewQueryTypeMapper::evaluateExpression PHP Method

    private function evaluateExpression(ContentView $contentView, $queryParameterValue)
    {
        if (substr($queryParameterValue, 0, 2) === '@=') {
            $language = new ExpressionLanguage();
            return $language->evaluate(substr($queryParameterValue, 2), ['view' => $contentView, 'location' => $contentView->getLocation(), 'content' => $contentView->getContent()]);
        } else {
            return $queryParameterValue;
        }
    }