Problem with optional non-capturing group in Regex

user_5655772 0
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I am trying to do regex parsing and matching and optionally discard the rest of the string.

My strings are of type:

[GROUP 1][delimiter 1][GROUP 2][delimiter 2][GROUP 3][delimiter 3 - optional][REST OF THE STRING - optional]

For example:

07. Neospace - Into The Night (Chris Van Buren)
13. Atomic Space Orchestra - Starfleet

I am trying to capture GROUP 1, GROUP 2 and GROUP 3 while ignoring REST OF THE STRING

The following regex works well if [delimiter 3] is present:

(\d+)\. (.*) - (.*)(?: \()

I am getting "07", "Neospace" and "Into The Night". But for the second string, there is no match, because my last non-capturing group is mandatory. When I'm trying to make last group optional like this:

(\d+)\. (.*) - (.*)(?: \()? non-capturing group stops working and I am getting "Into The Night (Chris Van Buren)" for the GROUP 3 - which is NOT what I want.

regex-group regex
1 Answers

If the 3rd group has ( as a delimiter, you can use a negated character class to exclude matching a ( char.

Note that using * as a quantifier can also match an empty string between the delimiters.

If the match should be at the start of the string, you can prepend the pattern with ^

(\d+)\. (.*?) - ([^(\n]*)

Explanation

  • (\d+) Capture group 1, match 1+ digits
  • \. Match .
  • (.*?) Capture group 2, match 0+ times any character, as few as possible
  • - Match literally
  • ([^(\n]*) Capture group 3, match 0+ times any character except ( or a newline

See a regex demo.

user_54249880
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