Find source na replacement parameters in a string and perform replacement in another string - oracle

Question

I need a function that applies a certain rule to replace words in a string.
There are two variables:
v_imp_user_list - list of users delimited by pipe (example: JOHN|PETER|MARK|USER_PROD)
v_schema_remap_list - list of users that should be remapped (old value - new value, example: JOHN-GEORGE,USER_PROD-USER_TEST)
The function should parse v_schema_remap_list variable and if the name of the first user (before dash, old value)
exist in v_imp_user_list then replace it with the second user (after dash, new value).
Example:
v_imp_user_list := 'JOHN|PETER|MARK|USER_PROD'
v_schema_remap_list := 'JOHN-GEORGE,USER_PROD-USER_TEST'
Desired outcome:
GEORGE|PETER|MARK|USER_TEST
I have a solution which I will post but for some reason I don't like it and will appreciate any comment/review/better solution.

Answer 1

This function helps me to parse the v_schema_remap_list.
-- extract nth occurence in a delimited string
create or replace function f_find_str (
source_string varchar2
, occurence_outer number --occurence of the old-new pair
, occurence_inner number --old/new value, enter 1 for old or 2 for new
)
return varchar2
is
v_aux varchar2(500);
v_result varchar2(100);
begin
v_aux := ltrim(regexp_substr(',' || source_string, ',[^,]*', 1, occurence_outer),',');
if occurence_inner = 1 then
v_result := substr(v_aux, 1, instr(v_aux, '-')-1);
elsif occurence_inner = 2 then
v_result := substr(v_aux, instr(v_aux, '-')+1);
end if;
return v_result;
end;
/
This anonymous block shows my solution (see the loop inside).
declare
v_schema_remap_list varchar2(1000) := 'JOHN-GEORGE,USER_PROD-USER_TEST';
v_imp_user_list varchar2(1000) := 'JOHN|PETER|MARK|USER_PROD';
v_schema_remap_cnt number := nvl(regexp_count(v_schema_remap_list, '-'), 0);
begin
for i in 1..v_schema_remap_cnt
loop
v_imp_user_list := replace(
v_imp_user_list||'|',
f_find_str (
source_string => v_schema_remap_list
, occurence_outer => i
, occurence_inner => 1
)||'|',
f_find_str (
source_string => v_schema_remap_list
, occurence_outer => i
, occurence_inner => 2
)||'|'
);
v_imp_user_list := rtrim(v_imp_user_list, '|');
end loop;
dbms_output.put_line(v_imp_user_list); --test output
end;
/