Replace commas within parantheses using regular expression

Question

I have a requirement in Python that I need to replace all the commas with a unique character, such as "$" or "|" , using regular expression. I tried doing so but not able to achieve my objective.

Please find below a sample string where I need to replace.

For eg consider the string below :-

SELECT 'column1' AS "Column 1" , 
  'column2' AS "Column 2" , 
  'column3' AS "Column 3", 
SUM(Column_1, Column_2) , 'column5' AS "Column 5" ,
CONCAT("str1","str2","str3") , 
ADD(len(str1),avg(column_1),sum(column_1,column_2,column_3)) 

In the above string i want to replace all the commas inside parentheses with "$" ie

SUM(Column_1 $ Column_2)
CONCAT("str1"$"str2"$"str3")
ADD(len(str1)$avg(column_1)
  $sum(column_1$column_2$column_3))

I have to do this with the help of regular expressions. I was able to do this for 2 values, means that when there is only one comma inside the ( ) I was able to replace but when tested with the scenario of more than one comma, my expression failed.

Answer 1

A regex like this? (\\s?,\\s?)(?=[^\\(]*\\))|(\\s?,\\s?)(?=(?:[^\\(]*\\([^\\(]*?\\))*\\))

see: https://regex101.com/r/uT1gQ7/3

It matches the comma with optional spaces around it, if it is followed by ) before another ( appears, using lookahead , looking at level 1 deepness. The second alternative looks if the remaining string has an aditional ) besides other (stuff) structures, It should do the trick.