Python: Regex match or condition?

Question

I have a string like {string}{string}{string} which I'm able to parse by

import re
input_string = '{string}{string}{string}'
for match in re.finditer(r'{([^}]*)}', input_string):
     print str(match.group(0)) #outputs {string}

but I also want to catch strings with an asterick following a curly bracket.

input_string = '{string}{string}*{string}{string}*'

How do I modify the regex so that both {string} and {string}* will be caught?

I tried doing r'{([^}]*)}|*' but doesn't seem to be working.

Also, what if a string contains curly brackets? ex. {string{3}} How do I make sure only the outer {} is caught and not the one's inside?

what the....I was gonna accept a really great answer but it's gone. — I Love Python, Nov 13 '13 at 08:18
Sorry, I had missed writing a response to your second question; undeleted. — Dogbert, Nov 13 '13 at 08:19

score 1 · Accepted Answer · edited May 23 '17 at 11:50

1

Add \*? at the end of your regex to match an optional *.

import re
input_string = '{string}{string}*{string}{string}*'
for match in re.finditer(r'{([^}]*)}\*?', input_string):
     print str(match.group(0)) #outputs {string}

Output:

{string}
{string}*
{string}
{string}*

As for nested brackets, simple regular expressions cannot parse that. You can use recursive regular expressions for this, but it becomes unreadable (example). You should use a proper parsing library, more discussion and examples here.

edited May 23 '17 at 11:50

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answered Nov 13 '13 at 08:09

Dogbert

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ah I see, it fails when there's a nested bracket – I Love Python Nov 13 '13 at 08:21
It will match the first closing bracket after an opening bracket. It'll match `{{a}` for input `{{a}}`. – Dogbert Nov 13 '13 at 08:22

Python: Regex match or condition?

1 Answers1