issue with string construction in plsql - regex

Question

I am having a string like
LEAST("col1", "col2") GREATEST("col1", "col2")
and from this string I want to a resultant string like
col1 IN LEAST(v_col1, v_col2) AND col2 IN GREATEST(v_col1, v_col2)
where v_ is appended to the column name and they represent predefined variables.
Number of columns can be dynamic.
I have tried too many options but I am not able to get the desired result.
Please suggest.
This are few options I am trying but seems not moving in right direction.
declare txt varchar2(1000);
anstxt varchar2(1000);
begin
txt := 'LEAST("col1","col2")';
select REGEXP_SUBSTR(TXT,'"([^"]*)"',1,1,'',1) into anstxt from dual;
DBMS_OUTPUT.PUT_LINE(anstxt);
end;
declare
v_Var5 varchar2(50);
v_Var6 varchar2(1000);
v_Var7 varchar2(10);
v_Var8 varchar2(10);
CURSOR c3 IS
SELECT column_expression FROM all_ind_expressions WHERE table_owner = 'schemaname' AND table_name = 'mytable';
names_t c3%ROWTYPE;
TYPE names_ntt IS TABLE OF names_t%TYPE; -- must use type
l_names names_ntt;
BEGIN
v_Var7 := ' IN (';
v_Var8 := ');';
--FOR i in c3
OPEN c3;
FETCH c3 BULK COLLECT INTO l_names;
CLOSE c3;
FOR indx IN 1..l_names.COUNT LOOP
IF(l_names.COUNT > 1) THEN
v_Var6 := v_Var6 || REPLACE(l_names(indx).column_expression, '"', '');
DBMS_OUTPUT.PUT_LINE(l_names(indx).column_expression);
ELSE
v_Var6 := REPLACE(l_names(indx).column_expression, '"', '');
END IF;
END LOOP;
v_Var6 := v_Var7 || REPLACE(v_Var6, ' ', ' AND ') || v_Var8;
--DBMS_OUTPUT.PUT_LINE(v_Var5);
DBMS_OUTPUT.PUT_LINE(v_Var6);
END;
Regards.

Answer 1

After so much trials, I have finally got what I was looking for.
I am sharing this for the forum's reference.
DECLARE
v_Var5 varchar2(1000);
v_Var6 varchar2(1000);
v_Var7 varchar2(10);
v_Var8 varchar2(10);
v_Var9 varchar2(1000);
v_Counter NUMBER;
CURSOR c3 IS
SELECT column_expression FROM all_ind_expressions WHERE table_owner = 'myschema' AND table_name = 'mytable';
names_t c3%ROWTYPE;
TYPE names_ntt IS TABLE OF names_t%TYPE; -- must use type
l_names names_ntt;
BEGIN
v_Counter := 1;
v_Var7 := ' IN (';
v_Var8 := ');';
OPEN c3;
FETCH c3 BULK COLLECT INTO l_names;
CLOSE c3;
FOR indx IN 1..l_names.COUNT
LOOP
--v_Counter := l_names.COUNT;
IF(l_names.COUNT > 1) THEN
v_Var6 := REPLACE(l_names(indx).column_expression, '"', '');
FOR i IN 1..l_names.COUNT LOOP
v_Var6 := REPLACE(v_Var6, REGEXP_SUBSTR(l_names(i).column_expression,'"([^"]*)"',1,i,'',1),'v_' || REGEXP_SUBSTR(l_names(i).column_expression,'"([^"]*)"',1,i,'',1));
END LOOP;
v_Var9 := REGEXP_SUBSTR(l_names(indx).column_expression,'"([^"]*)"',1,indx,'',1) || ' IN (';
CASE
WHEN indx < l_names.COUNT THEN
v_Var5 := v_Var5 || v_Var9 || v_Var6 || ') AND ';
WHEN indx = l_names.COUNT THEN
v_Var5 := v_Var5 || v_Var9 || v_Var6 || ');';
END CASE;
ELSE
v_Var6 := REPLACE(l_names(indx).column_expression, '"', '');
v_Var6 := REPLACE(v_Var6, REGEXP_SUBSTR(l_names(indx).column_expression,'"([^"]*)"',1,indx,'',1),'v_' || REGEXP_SUBSTR(l_names(indx).column_expression,'"([^"]*)"',1,indx,'',1));
v_Var9 := REGEXP_SUBSTR(l_names(indx).column_expression,'"([^"]*)"',1,indx,'',1) || ' IN ';
v_Var5 := v_Var5 || v_Var9 || v_Var6;
END IF;
END LOOP;
--DBMS_OUTPUT.PUT_LINE('v_Var9' || CHR(13) || v_Var9);
--DBMS_OUTPUT.PUT_LINE('v_Var6' || CHR(13) ||v_Var6);
DBMS_OUTPUT.PUT_LINE('v_Var5' || CHR(13) ||v_Var5);
END;