Huh, did not realize that endswith takes a list. I'll remember that in the future.
This need is actually for http://schemaspy.sourceforge.net/, which allows one to include only tables/views that match a pattern. Either there is a bug in Schemaspy's code or Java's implementation of regular expressions is different than Python's or there is a flaw in my logic, because the pattern I verify using Python produces different results when used with Schemaspy. I suppose I'll open a bug there unless I can find the aforementioned flaw. On Mon, Jul 1, 2013 at 11:44 PM, Ian Kelly <ian.g.ke...@gmail.com> wrote: > On Mon, Jul 1, 2013 at 8:27 PM, Jason Friedman <jsf80...@gmail.com> wrote: > > Found this: > > > http://stackoverflow.com/questions/13871833/negative-lookahead-assertion-not-working-in-python > . > > > > This pattern seems to work: > > pattern = re.compile(r"^(?!.*(CTL|DEL|RUN))") > > > > But I am not sure why. > > > > > > On Mon, Jul 1, 2013 at 5:07 PM, Jason Friedman <jsf80...@gmail.com> > wrote: > >> > >> I have table names in this form: > >> MY_TABLE > >> MY_TABLE_CTL > >> MY_TABLE_DEL > >> MY_TABLE_RUN > >> YOUR_TABLE > >> YOUR_TABLE_CTL > >> YOUR_TABLE_DEL > >> YOUR_TABLE_RUN > >> > >> I am trying to create a regular expression that will return true for > only > >> these tables: > >> MY_TABLE > >> YOUR_TABLE > >> > >> I tried these: > >> pattern = re.compile(r"_(?!(CTL|DEL|RUN))") > >> pattern = re.compile(r"\w+(?!(CTL|DEL|RUN))") > >> pattern = re.compile(r"(?!(CTL|DEL|RUN)$)") > >> > >> But, both match. > >> I do not need to capture anything. > > > For some reason I don't seem to have a copy of your initial post. > > The reason that regex works is because you're anchoring it at the > start of the string and then telling it to match only if > ".*(CTL|DEL|RUN)" /doesn't/ match. That pattern does match starting > from the beginning of the string, so the pattern as a whole does not > match. > > The reason that the other three do not work is because the forward > assertions are not properly anchored. The first one can match the > first underscore in "MY_TABLE_CTL" instead of the second, and then the > next three characters are "TAB", not any of the verboten strings, so > it matches. The second one matches any substring of "MY_TABLE_CTL" > that isn't followed by "CTL". So it will just match the entire string > "MY_TABLE_CTL", and the rest of the string is then empty, so does not > match any of those three strings, so it too gets accepted. The third > one simply matches an empty string that isn't followed by one of those > three, so it will just match at the very start of the string and see > that the next three characters meet the forward assertion. > > Now, all that said, are you sure you actually need a regular > expression for this? It seems to me that you're overcomplicating > things. Since you don't need to capture anything, your need can be > met more simply with: > > if not table_name.endswith(('_CTL', '_DEL', '_RUN')): > # Do whatever > -- > http://mail.python.org/mailman/listinfo/python-list >
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