Validating regexp

[Larry Martell]

On Tue, Aug 8, 2017 at 12:51 PM, Chris Angelico <rosuav at gmail.com> wrote:
> On Wed, Aug 9, 2017 at 2:37 AM, Larry Martell <larry.martell at gmail.com> wrote:
>> Anyone have any code or know of any packages for validating a regexp?
>>
>> I have an app that allows users to enter regexps for db searching.
>> When a user enters an invalid one (e.g. 'A|B|' is one I just saw) it
>> causes downstream issues. I'd like to flag it at entry time.
>
> re.compile()? Although I'm not sure that 'A|B|' is actually invalid.
> But re.compile("(") throws.

Yeah, it does not throw for 'A|B|' - but mysql chokes on it with empty
subexpression for regexp' I'd like to flag it before it gets to SQL.