UNDEFINE TEXT
WITH STRING AS (SELECT '&&TEXT' AS STR FROM DUAL),
DE_STRING AS(
    SELECT STR, SUBSTR(STR,LEVEL,1) SS, ROWNUM RN
    FROM STRING
    CONNECT BY LEVEL <= LENGTH(STR)),
PARENTHESIS AS(
    SELECT STR, SS, ROWNUM R
        FROM DE_STRING
            WHERE SS IN ('(',')')
            ORDER BY RN),
DE_PARENTHESIS AS(
    SELECT STR, TO_NUMBER(CASE SS WHEN '(' THEN 1 ELSE -1 END) AS SS, R FROM PARENTHESIS),
RESULT AS(
    SELECT STR, SS, R, (SELECT SUM(SS) FROM DE_PARENTHESIS WHERE R<=EXT.R) AS RESULT FROM DE_PARENTHESIS EXT
    START WITH R = 1
    CONNECT BY PRIOR R = R-1),
IS_MINUS AS(
    SELECT DISTINCT 1 AS BAD_MINUS FROM RESULT WHERE RESULT <0),
IS_PLUS AS(
    SELECT DISTINCT 1 AS BAD_PLUS FROM RESULT WHERE (SELECT SUM(SS) FROM RESULT)>0),
REF AS(
    SELECT
        CASE
            WHEN (SELECT * FROM IS_MINUS)=1 OR (SELECT * FROM IS_PLUS)=1 THEN NULL
            ELSE (SELECT DISTINCT STR FROM RESULT)
        END
    AS STR FROM DUAL)
SELECT DISTINCT STR
FROM RESULT
WHERE STR IN(SELECT * FROM REF);