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Re: how to use parsing expressing grammar


From: Mike Mattie
Subject: Re: how to use parsing expressing grammar
Date: Thu, 5 Mar 2009 08:38:06 -0800

On Tue, 3 Mar 2009 14:05:39 -0800 (PST)
Xah Lee <address@hidden> wrote:

> On Mar 3, 9:59 am, Mike Mattie <address@hidden> wrote:
> > On Tue, 03 Mar 2009 17:34:41 +0000
> >
> > Leo <address@hidden> wrote:
> > > On 2008-12-21 09:49 +0000, Helmut Eller wrote:
> > > >> I'm pretty sure if you create it, more and more people will
> > > >> join it. I'm very interested in PEG and think it is of critical
> > > >> importance.
> >
> > > > I'll try to set up project at savannah.
> >
> > > I have seen the project on
> > >http://savannah.nongnu.org/projects/emacs-peg. I wonder it might
> > >be a
> > > good idea to make a newsgroup on gmane to link to the mailing
> > > list. It will make more Emacs users subscribe to it.
> >
> > > Best wishes,
> >
> > I was working on a PEG/CFG parser
> > compiler:http://www.emacswiki.org/cgi-bin/wiki/ParserCompiler
> >
> > I will be resuming the development soon. Please keep me in the loop
> > on such efforts.
> 
> Folks,
> 
> when you create a PEG parser, please please make it user oriented one,
> so that any user of emacs familiar with regex find-replace will be
> able to use PEG for find-replace. In particular, when doing find-
> replace on nested text such as XML.
> 
> regex is powerful, but it doesn't do nested text. PEG comes to the
> rescue. However, it needs to be regex-like, in the sense that the
> program interface will be a simple source text and replacement text.
> e.g. a function peg-replace that takes 2 args, pattern text, and text
> source. The pattern text can be the region, buffer, or a filename, the
> text source to work on can be similar. (thus, maybe peg-replace-
> region, peg-replace-buffer, peg-replace-file etc.)
> 
> last time i was looking at PEG, i opted to try Helmut Eller's version
> because it seems simpler. (mike's version is far more compiler geeking
> incomprehensible) But still problematic to use. I got busy in other
> things so i didn't continue on studying it, so i dropped out of this
> thread (havn't read Helmut's last message in detail). Rather, i simply
> want just to use it. Last in this thread, he mentioned about stacks
> and i went huh... and just didn't have time to go further.
> 
> Regex is practically extremely useful, a tool every programer uses
> today. However, regex cannot work with nested text such as XML/HTML,
> which is used extensively, probably more so than any programing lang
> or text. So, brigining regex power to html/xml will be a major impact
> on not just emacs, but the whole programing industry. PEG, practically
> speaking, is basically just the next generation of so-called regex.
> Emacs can be the first to have such a feature. (existing PEG
> implementations in various lang,  at this point, as far as i know, are
> all tech geeking toys, done by geekers interested in language parsing
> and so on.)
> 
> Personally, i have huge need for regex that can work on html.
> PEG is of course not just a regex replacement, but a BNF replacement
> in the sense it is actually for machines to read. For these reasons
> that's how i got heavily interested in PEG. (see:
> • Pattern Matching vs Lexical Grammar Specification
>   http://xahlee.org/cmaci/notation/pattern_matching_vs_pattern_spec.html
> )
> 
> Please make your PEG in emacs with a regex-like API. Something any
> emacs user familiar with regex will be able to use brainlessly. This
> will be huge...
> 
> i had plans to open a mailing list and stuff... but got busy with
> other things. I'll come back to this. But i hope you are convienced
> about making PEG usable as a text-editing tool, as opposed to a tool
> for computer scientist or compiler/parser writers.
> 
> Also, Mike & Helmut, please consider putting your code in goode code.
> Google Code is very popular, probably today the most popular code
> building service, and extremely easy to use, and from my studies
> Google's products and services are all extremely high quality. It
> would help a lot in your software at least in the marketing aspect if
> you use Google Code. Also, open a google group is very useful and
> popular. (yasnippet is a successful example for a emacs project on
> google code. There are several others, including e.g. js2, ejacs, the
> erlang one, etc.) Going into Savana or anything on FSF services tend
> to be a dead end. (yeah, controversy, but whatever.)
> 
>   Xah
>http://xahlee.org/
> 
>

Making it simple to use is possible, and a goal. My project is not there
yet. There are still some thorny issues to work out. Until then it will
be very geeky :)

Overcoming the use issue will IMHO require good documentation with *alot*
of examples. When I am writing that I will let you know.

Cheers,
Mike Mattie




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