Regex for string matching with special escaping rule

Question

I'm trying to match special kind of string literals with some funky escaping rules.

The general form looks like this:

"some string"

Which are simple to match using a pattern such as "(.*?)"

However you can escape quotes by doubling them, such as:

"hello "" there" becomes hello " there
"hello """" there" becomes hello "" there

And this is where my regex skills fail me. How can I match strings like this?

Oh, and I'm using python 3.1.

Answer 1

regex = re.compile(r'"(?:[^"]|"")*"')

This just finds the literals, it doesn't decode them by replacing the doubled quotes.

Answer 2

Not using a regular expression, but you've specified Python, so here's a way to get your expected output:

>>> import csv
>>> strings = ['"some string"', '"hello "" there"', '"hello """" there"']
>>> for s in strings:
    print next(csv.reader([s]))


['some string']
['hello " there']
['hello "" there']