How do I write a complex regex as string in python3?

Question

So, I've got this regex I would like to compile:

(?<!\\)(?:(')|")(?(1)(\\'|[^'\r])+?'|(\\"|[^\r"])+?")

It works fine. But because there are ' and " signs, I need to escape them. So I do:

re.compile('''(?<!\\)(?:(')|")(?(1)(\\'|[^'\r])+?'|(\\"|[^\r"])+?")''')

Which give me the 'unbalanced parenthesis' error. I also tried:

re.compile('(?<!\\)(?:(\')|")(?(1)(\\\'|[^\'\r])+?\'|(\\"|[^\r"])+?")')

Are all those backslashes confusing it, somehow? It's hard enough to understand without having to add more backslashes to escape the backslashes...

Ignacio Vazquez-Abrams · Accepted Answer · 2013-06-30 23:47:00Z

4

Yes, they are. Use a raw string.

>>> re.compile(r'(?<!\\)(?:(\')|")(?(1)(\\\'|[^\'\r])+?\'|(\\"|[^\r"])+?")')
<_sre.SRE_Pattern object at 0x242aa60>

answered Jun 30, 2013 at 23:47

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3 Comments

Ah, that's what those little r's mean I've been seeing here and there. Thanks

It makes more sense to use a triple-quoted string (as in the original post) instead of escaping quote characters.

Sure, but the problem is not the quotes.