Java regex: Repeating capturing groups

Question

An item is a comma delimited list of one or more strings of numbers or characters e.g.

"12"
"abc"
"12,abc,3"

I'm trying to match a bracketed list of zero or more items in Java e.g.

""
"(12)"
"(abc,12)"
"(abc,12),(30,asdf)"
"(qqq,pp),(abc,12),(30,asdf,2),"

which should return the following matching groups respectively for the last example

qqq,pp
abc,12
30,asdf,2

I've come up with the following (incorrect)pattern

$(.+?)$(?:,$(.+?)$)*

which matches only the following for the last example

qqq,pp
30,asdf,2

Tips? Thanks

user_6010052 · Answer

Using an ANTLR grammar can solve this problem. This is really beyond the reasonable capabilities of RegExp, although I believe some newer versions of Microsoft's implementation in .Net support this behavior. See this other SO question. If you're stuck with everything but .Net your best option is going to be a parser-generator (you don't have to use ANTLR, that's just my personal preference). Going through the ANTLR4 GitHub page can help get someone started on matching on more complex expressions with things like repeating match groups. Another option that doesn't require a whole lot of new learning is to tokenize the string input that you're wanting to match on and pull out the pieces that you want, but this can prove to be extremely messy and create nightmarish chunks of parsing code that are better-suited to a generated parser.