-- Name: trim_parens(text); Type: FUNCTION; Schema: util; Owner: -

--

CREATE FUNCTION trim_parens(str text) RETURNS text

    LANGUAGE sql IMMUTABLE

    AS $_$

SELECT CASE WHEN /*base case*/inner_str IS NULL THEN str

ELSE util.trim_parens(inner_str) END

FROM (SELECT (SELECT regexp_matches(str, '^\((.*)\)$'))[1] AS inner_str) s

$_$;

--