protected function normalizeComparison($operator)
    {
        switch (strtolower($operator)) {
            case '<':
            case 'lt':
                return '<';
            case '<=':
            case 'lte':
                return '<=';
            case '>':
            case 'gt':
                return '>';
            case '>=':
            case 'gte':
                return '>=';
            case '~':
            case '~=':
            case '=~':
            case 'regex':
            case 'regexp':
                return "regexp";
            // LIKE
            case 'like':
                return "like";
            case '||':
            case 'fulltext':
            case 'fulltext_boolean':
                return 'fulltext';
            case '<>':
            case '!=':
            case 'ne':
            case 'not':
                return '!=';
            case '=':
            case 'eq':
                return '=';
            default:
                throw new QueryException(sprintf('Query does not supports comparison operator "%s" in query "%s"', $operator, $this->model()->entity()));
        }
    }