From: "Aurélien Aptel" <aurelien.aptel@gmail.com>
To: Achim Gratz <Stromeko@nexgo.de>
Cc: emacs-orgmode@gnu.org
Subject: Re: GSoC 2012 -- Elisp backend for Ragel
Date: Wed, 28 Mar 2012 00:11:08 +0200 [thread overview]
Message-ID: <CA+5B0FNeMOGrbUYDYkn50cxQX7UEfh5KkeaZhOZTfozji3=zJQ@mail.gmail.com> (raw)
In-Reply-To: <87sjgtoi1o.fsf@Rainer.invalid>
On Tue, Mar 27, 2012 at 11:22 PM, Achim Gratz <Stromeko@nexgo.de> wrote:
> It needs yet another tool to fully build org-mode from scratch, which
> needs to be installed, bug-free and configured correctly. Right now all
> one really needs to have to build org-mode is a working Emacs (even make
> is optional).
Ragel is written in C++ and has no dependency.
* every major platform has a C++ compiler
* ragel input along with generated code can be tracked in the repo
* the generated code is portable since it's elisp (doesn't need to be
regenerated on different platforms)
* the parser is a confined part of org-mode
I don't think this is a problem.
>>> 3) FSM implementation into code is inherently very simple anyway
>>
>> Well I've never done it for big language but I did not find it that
>> easy. Mistakes are easily made e.g. you end up accepting more thing
>> that the language does in order to simplify the code, etc.
>
> Which is just as easily done by specifying the syntax incorrectly.
I think the fix will be shorter and simpler in the syntax because it's
easier to reason on an abstract definition when it comes to language.
When you're neck-deep in your handwritten implementation trying to
figure what you did wrong, it can take a long time.
> No, you can (for a suitably restricted set of languages) formally proof
> that the implementation and the specification is identical for any
> input.
How would you do that programmatically?
> The assumption that an FSM running in ELisp is faster than a bunch of
> regexp has not been actually tested or has it?
I haven't tested anything yet.
If I remember correctly, the emacs regex API doesn't provide a way to
compile patterns and thus have to be compiled at each call.
Also the underlying FSM implementation uses NFA which can lead to a
exponential complexity in time [1] for certain patterns.
1: http://swtch.com/~rsc/regexp/regexp1.html
next prev parent reply other threads:[~2012-03-27 22:11 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-22 13:43 GSoC 2012 -- Elisp backend for Ragel Rustom Mody
2012-03-23 11:12 ` Aurélien Aptel
2012-03-23 11:36 ` Rustom Mody
[not found] ` <CAJ+TeoebkVTLs9nrDTH_6xvzvkk1vTEZDL2iHmEAkTUfZRjpjQ@mail.gmail.com>
[not found] ` <CAJ+TeoebkVTLs9nrDTH_6xvzvkk1vTEZDL2iHmEAkTUfZRjpjQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-03-25 4:17 ` Rustom Mody
2012-03-25 6:55 ` Rustom Mody
2012-03-25 10:06 ` Aurélien Aptel
2012-03-25 11:40 ` Nicolas Goaziou
2012-03-25 12:52 ` Martyn Jago
2012-03-27 20:34 ` Aurélien Aptel
2012-03-27 21:22 ` Achim Gratz
2012-03-27 22:11 ` Aurélien Aptel [this message]
2012-03-28 6:34 ` Achim Gratz
2012-03-29 17:50 ` Aurélien Aptel
2012-03-29 17:52 ` Samuel Wales
2012-03-29 19:04 ` Achim Gratz
[not found] ` <87vclsykl6.fsf-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-03-27 20:03 ` Aurélien Aptel
2012-03-26 16:01 ` Bastien
[not found] ` <87wr674aii.fsf-mXXj517/zsQ@public.gmane.org>
2012-03-27 20:49 ` Aurélien Aptel
2012-03-27 22:10 ` Bastien
2012-03-26 15:53 ` Bastien
-- strict thread matches above, loose matches on Subject: below --
2012-03-21 18:51 Aurélien Aptel
2012-03-21 19:32 ` Aurélien Aptel
2012-03-21 19:34 ` Samuel Wales
2012-03-22 12:22 ` Thorsten
2012-03-24 8:16 ` Nicolas Goaziou
2012-03-26 16:03 ` Bastien
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