oracle split by comma a quoted string

I have found tons of questions like this, but none of them are 100% suitable for me. i have oracle 11g express

I have that string

'abcd,123,,defoifcd,"comma, in string",87765,,,hello'

it means normally a comma separates the data, but could be empty data (even more in a series), and if there is comma in the data it is quoted.

so far the best reg exp is that one

'("[^"]*"|[^,]+)'

but this puts at the end of all of the empty data using that query

with test as 
(select 
'abcd,123,,defoifcd,"comma, in string", 87765,,,hello'
str from dual  
)  
select REGEXP_SUBSTR(str, '("[^"]*"|[^,]+)', 1, rownum) split
from test  
connect by level <= length (regexp_replace (str, '("[^"]*"|[^,]+)'))  + 1;

i also tried replacing the empty data with ,n/a, so to have

'abcd,123,n/a,defoifcd,"comma, in string",87765,n/a,n/a,hello'

but regexp_replace replaces only the first occurence of the empty data

select 
regexp_replace('abcd,123,,defoifcd,"comma, in string",87765,,,hello', '(,,)', ',n/a,')
str from dual;

thanks in advance!

Solution

This seems to work and handles NULLs:

SQL> with test as
    (select
    'abcd,123,,defoifcd,"comma, in string", 87765,,,hello'
    str from dual
    )
    select trim('"' from REGEXP_SUBSTR(str, '(".*?"|.*?)(,|$)', 1, level, NULL, 1)) split
    from test
    connect by level<=length(regexp_replace(str,'".*?"|[^,]*'))+1;

SPLIT
----------------------------------------------------
abcd
123

defoifcd
comma, in string
 87765


hello

9 rows selected.

SQL>

This post provided the impetus for the solution: https://community.oracle.com/thread/528107?tstart=0