First time posting so be gentle. My goal was to match a group of characters (except if numeric) inside the first set of brackets delimited by a comma while ignoring white spaces. The trick was to not match the comma nested in another set of brackets. My solution seems to work so I wanted to share my solution and also get input on any other better solutions.
My example input string is:
test[ [a], b1 , 1,2 , cc[nn[ 99],oo[ g , l]],dd].test2[ ee , 22 ]
Desired matches:
1. "[a]"
2. "b1"
3. "cc[nn[ 99],oo[ g , l]]"
4. "dd"
5. "ee"
Solution:
Regex regexObj = new Regex(
@"(?<=[,\[]\s*) (?# Match must start with, but not include, opening bracket or comma)
(?![0-9]) (?# Do not match if followed by a number)
(?> (?# Start atomic group, do not backtrack inside the match)
(?(DEPTH) (?# Check IF inside an un-closed bracket group THEN)
[^\[\]] (?# match any char except brackets)
| (?# ELSE closed)
[^\s,\[\]]) (?# delimit by comma)
| (?# OR)
(?'DEPTH'\[) (?# Match open bracket and increase DEPTH count)
| (?# OR)
(?'-DEPTH'\]) (?# Match closed bracket and decrease DEPTH count)
)* (?# Continue atomic group)
(?(DEPTH)(?!)) (?# Ensure the match has a balanced set of brackets)
(?=\s*[,\]]) (?# Match must end with a comma or closing bracket)",
RegexOptions.IgnorePatternWhitespace);
The example I worked from is found here C# Regex - How to remove multiple paired parentheses from string
