searching backwards in a string

[Jason Orendorff]

Steve Holden wrote:
> If you'd like to find the "last match before a given position" then,
> supposing string p to represent the regex matching the pattern you are
> looking for, you can try match()'ing
> 
>     ".*(%s)" % p
> 
> Given the greedy nature of matching, this should give you the rightmost
> match in groups(1). Maybe. Anyway, an idea to play with.

Hey, that's pretty clever!  I wonder about the performance, though...
Anyway, remember that by default .* won't cross newlines.
So: r"(.|\n)*(%s)".  Or you could re.DOTALL, but that may change
the meaning of the other regular expression you're plugging in.

## Jason Orendorff    http://www.jorendorff.com/