From: Daniel Colascione <dancol@dancol.org>
To: "Perry E. Metzger" <perry@piermont.com>
Cc: Stefan Monnier <monnier@iro.umontreal.ca>, emacs-devel@gnu.org
Subject: Re: [Emacs-diffs] master 938d252 4/4: Make regex matching reentrant; update syntax during match
Date: Tue, 19 Jun 2018 07:46:01 -0700 [thread overview]
Message-ID: <e9f47aa0-7790-8472-7bd2-b0242930e7ef@dancol.org> (raw)
In-Reply-To: <20180619103002.4f000018@jabberwock.cb.piermont.com>
On 06/19/2018 07:30 AM, Perry E. Metzger wrote:
> On Tue, 19 Jun 2018 06:49:03 -0700 Daniel Colascione
> <dancol@dancol.org> wrote:
>> On 06/19/2018 06:44 AM, Perry E. Metzger wrote:
>>> On Tue, 19 Jun 2018 09:40:05 -0400 "Perry E. Metzger"
>>> <perry@piermont.com> wrote:
>>>> On Mon, 18 Jun 2018 10:49:46 -0700 "Daniel Colascione"
>>>> <dancol@dancol.org> wrote:
>>>>>> I think the right thing would be to use TRE if we could get
>>>>>> Ville Laurikari to let someone else be the maintainer. Sadly
>>>>>> right now it seems unmaintained and has been for years, but
>>>>>> it's fast, complete, and has the ability to handle things like
>>>>>> gap buffers.
>>>>>
>>>>> Last time I looked, many years ago, there were several bugs (or
>>>>> differences between TRE and POSIX anyway)
>>>>
>>>> Bugs yes, but the POSIX conformance was pretty strict. As I
>>>> said, he seemed to have abandoned the thing, but the bones are
>>>> pretty good. Someone could just fork it and implement all the
>>>> patches people have been contributing that have been languishing
>>>> in the github issue trackers.
>>>
>>> Oh, and re2 isn't built for POSIX compliance. It has no constructs
>>> that require backtracking etc.
>>
>> No DFA engine can do backtracking.
>
> Correct, but there are regexp libraries that will switch between DFA
> and non-DFA implementations depending on whether the regexp has
> constructs in it that require backtracking
Sure, but the DFA and non-DFA engines can vary independently so long as
they understand the same language, modulo backreference support.
IMHO, back reference support is an old unix mistake. I can't think of a
time when I've wanted to actually use them, but their theoretical use is
still a hindrance. One option would be to just deprecate them.
next prev parent reply other threads:[~2018-06-19 14:46 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180616204650.8423.73499@vcs0.savannah.gnu.org>
[not found] ` <20180616204653.86AFC203CB@vcs0.savannah.gnu.org>
2018-06-17 18:42 ` [Emacs-diffs] master 938d252 4/4: Make regex matching reentrant; update syntax during match Stefan Monnier
2018-06-17 18:51 ` Daniel Colascione
2018-06-17 19:18 ` Daniel Colascione
2018-06-17 19:34 ` Stefan Monnier
2018-06-17 19:50 ` Daniel Colascione
2018-06-17 19:30 ` Stefan Monnier
2018-06-18 15:59 ` Perry E. Metzger
2018-06-18 17:49 ` Daniel Colascione
2018-06-19 13:40 ` Perry E. Metzger
2018-06-19 13:44 ` Perry E. Metzger
2018-06-19 13:49 ` Daniel Colascione
2018-06-19 14:30 ` Perry E. Metzger
2018-06-19 14:33 ` Perry E. Metzger
2018-06-19 14:48 ` Daniel Colascione
2018-06-19 15:37 ` Perry E. Metzger
2018-06-19 16:20 ` Paul Eggert
2018-06-19 16:27 ` Perry E. Metzger
2018-06-19 17:46 ` Stefan Monnier
2018-06-19 18:18 ` Daniel Colascione
2018-06-19 18:26 ` Perry E. Metzger
2018-06-19 16:54 ` John Wiegley
2018-06-19 17:04 ` Perry E. Metzger
2018-06-19 18:20 ` John Wiegley
2018-06-19 18:04 ` Paul Eggert
2018-06-19 18:16 ` Daniel Colascione
2018-06-19 18:26 ` Paul Eggert
2018-06-19 18:03 ` Andreas Schwab
2018-06-19 18:48 ` Paul Eggert
2018-06-19 14:46 ` Daniel Colascione [this message]
2018-06-19 14:58 ` Andreas Schwab
2018-06-19 15:32 ` Perry E. Metzger
2018-06-18 23:25 ` Richard Stallman
2018-06-19 1:30 ` Perry E. Metzger
2018-06-19 22:54 ` Richard Stallman
2018-06-20 1:17 ` Perry E. Metzger
2018-06-20 23:26 ` Richard Stallman
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