Comma-separated repeats

Question

I've got a pretty long regex to match an entry in a list I'm processing. The list should be one or more of these entries, comma-separated. Consider a regex:

([abc]+|[123]+)

for the entry. To match my comma-separated list, I'm matching against something like this:

([abc]+|[123]+)(,([abc]+|[123]+))*

(It looks especially foolish with my nasty regex instead of the short one I used here for the example)

I feel there must be a better way than having two copies of the entry -- once for the first entry, again for and follow comma/entry pairs.

Answer 1

Looks like you want backreferences.

([abc123])(,\1)*

Also, just FYI, [abc]|[123] is equivalent to [abc123].

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Edit: Based on your edit, I think I misunderstood what you were trying to do. Try this:

([abc123]+(,|$))*

Or if you want to be less restrictive:

([^,]+(,|$))*

This matches strings of non-comma characters separated by commas. A simpler approach would just be a global match for [^,]+ by itself. In JavaScript, that would look like this:

myString.match(/[^,]+/g) //or /[abc123]+/g, or whatever

Or you could just split on commas:

myString.split(/,/)