Problems with regexps

From: Kirk Strauser (kirk_at_daycos.com)
Date: 11/07/03 

Date: Fri, 07 Nov 2003 21:20:08 GMT

I'm writing a program to scan through a bunch of VB source.  An example of
one of the types of strings I'm trying to match is:

    response.write Request.Cookies ("domain")("cname")

but I do not want to match variable assignments like this (they are picked
up later by a different pattern):

    strXRSCust= Request.Cookies ("domain")("cname")

I'm differentiating between the two forms by looking for an equal sign
followed by zero or more spaces; if the '=' is there, then I don't want to
match.  Here's where it gets weird.  This pattern works perfectly (as long
as there are 1 or more spaces after the '='), in that it will not match
the assignment example above:

    re.compile(r'(?<!=)\s+Request.Cookies\s*((\(\s*".*?"\s*\)\s*)+)')

I really want to use the pattern below to match for zero or more spaces
(not one or more).  Note that it's identical except that the first '\s+'
is replaced with a '\s*':

    re.compile(r'(?<!=)\s*Request.Cookies\s*((\(\s*".*?"\s*\)\s*)+)')

I don't know why, but the second pattern does match the assignment example
above, although I don't think it should.

It seems like there's a problem with the negative lookbehind assertion and
that the variable-length '\s' pattern immediately following it is throwing
it off.  Any thoughts? 

-- 
Kirk Strauser
The Day Companies

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