Re: Psql regex is NFA or DFA?

Tom Lane wrote:
> Josh Jore <josh@greentechnologist.org> writes:
> > So I've finished reading Jeffery Friedl's _Mastering Regular Expressions_
> > and while I don't need regex in PostgreSQL I know I'll do it for something
> > - eventually. The book makes a distinction between DFA, POSIX NFA and
> > Traditional NFA and then ascribes some properties and behaviours to each.
> > So what sort does PostgreSQL have?
>
> Well, you could read the code (src/backend/regex), or you could apply
> the tests that Friedl suggests to distinguish the type of an unknown
> engine ...
>
> My guess is that it's an NFA, but I dunno if Spencer did the POSIX
> semantics or not.

I am continuing to talk to Henry about getting a newer version of his
regex library. He is working on it but is not yet finished.

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