Hello,
in one of my applications I want to match all file names except for
some with special extensions. I already have similar regexes with
lookbehind assertions, but those where simpler and only needed one
top level branch, the one I need now is a bit more complex. It doesn't
work as I thought because I use sub level branches with variable
matching length which is not permitted in lookbehind assertions.
The only solution to my problem which I found is to use a lookahead
assertion and negate the check for a match in my source code. As this
is easy to accomplish, I would rather avoid it because all used
regexes in the context of my application are used as whitelists with
lookbehind assertions and for the sake of consistency I would like to
use this problematic one as a whitelist, too.
The regex:
(?i)(?<!(?:(?:p7m|pk7|pkcs7)\.(?:p7m|pk7|pkcs7))|zip|zip\.(?:p7m|pk7|pkcs7))$
Some example filenames:
test.txt
test.txt.pk7
test.txt.p7m.pk7
test.txt.pkcs7.zip
test.txt.pkcs7.zip.p7m.pk7
The regex should only match the first and second file name.
I would really appreciate if some of you could have a look at the
regex and give me some hints about how I could rewrite it to a
functional lookbehind assertion or something similar usable as a
whitelist. Thanks for any ideas!
Mit freundlichen Grüßen,
Thorsten Schöning
--
Thorsten Schöning E-Mail:Thorsten.Schoening@???
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