From: Stefan Monnier <monnier@iro.umontreal.ca>
To: emacs-devel@gnu.org
Subject: Re: Improving regexp-opt
Date: Fri, 12 Apr 2019 12:53:06 -0400 [thread overview]
Message-ID: <jwvd0lrp3t8.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: CAARdmY0VxaC9LdACyv_uzGZ-9Sinj3BmknwFGR6dWvGk21gtkQ@mail.gmail.com
> The pros:
> If the resulting strings "came from" a regexp that is splittable, the
> FA implementation always simplifies to it. In pratice, these are
> uncommun, and in most cases, the results are equivalent.
>
> The cons:
> The algorithm for FA seams to have greater computation complexity,
> takes about 20 times to compute in average.
Furthermore, even when the result is noticeably shorter, have you
compared the performance of the regexp-matcher? I expect that you won't
be able to see a measurable difference there.
IOW it's just not a good deal.
As I said, if you really want to improve on regexp-opt, you have to go
through a *real* DFA and that means not returning a regexp but a DFA, so
it's a completely different beast from `regexp-opt`.
Stefan
next prev parent reply other threads:[~2019-04-12 16:53 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-07 16:41 Improving regexp-opt Miguel V. S. Frasson
2019-02-08 3:48 ` Stefan Monnier
2019-04-12 15:06 ` Miguel V. S. Frasson
2019-04-12 15:40 ` Miguel V. S. Frasson
2019-04-12 16:53 ` Stefan Monnier [this message]
2019-04-18 0:59 ` Miguel V. S. Frasson
2019-04-18 3:49 ` Stefan Monnier
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