Regular Expression Parser in Emacs Lisp

Regular Expression Parser in Emacs Lisp

[Nordlöw]

Has any body any reflections, ideas or even code snippets that could
be used to implement a regular expression parser in Emacs-Lisp?
My highest prio is supporting emacs-style regexps.

Thanks in advance,
Nordlöw

Re: Regular Expression Parser in Emacs Lisp

[Joost Kremers]

Nordlöw wrote:
> Has any body any reflections, ideas or even code snippets that could
> be used to implement a regular expression parser in Emacs-Lisp?
> My highest prio is supporting emacs-style regexps.

and why don't you use the one that's built into emacs?


-- 
Joost Kremers                                      joostkremers@yahoo.com
Selbst in die Unterwelt dringt durch Spalten Licht
EN:SiS(9)

Re: Regular Expression Parser in Emacs Lisp

[Nordlöw]

On Sep 25, 2:08 pm, Joost Kremers <joostkrem...@yahoo.com> wrote:
> Nordlöw wrote:
> > Has any body any reflections, ideas or even code snippets that could
> > be used to implement a regular expression parser in Emacs-Lisp?
> > My highest prio is supporting emacs-style regexps.
>
> and why don't you use the one that's built into emacs?
>
> --
> Joost Kremers                                      joostkrem...@yahoo.com
> Selbst in die Unterwelt dringt durch Spalten Licht
> EN:SiS(9)

My motivation:
I am currently implementing (in Emacs-Lisp) a sort of database layer
for file types based on both file name and contents patterns (compare
with file and libmagic) that are preferrably specified using regular
expressions. But to make this reasonably fast I need a way to figure
out if a regexp has a maximum match length and if so what that length
is.
This because I want to perform memory-local scanning of file contents
and only want to load as much of the file that I actually need.

/Nordlöw

Re: Regular Expression Parser in Emacs Lisp

[Joost Kremers]

Nordlöw wrote:
>  I need a way to figure
> out if a regexp has a maximum match length and if so what that length
> is.

do you need a full-blown regexp parser for that? AFAICT the regexp syntax
defines precisely which tokens may match more than one character, and in those
cases, the maximum number of characters matched is not given, so that the
maximum length is not defined.


-- 
Joost Kremers                                      joostkremers@yahoo.com
Selbst in die Unterwelt dringt durch Spalten Licht
EN:SiS(9)

Re: Regular Expression Parser in Emacs Lisp

[Ilya Zakharevich]

On 2009-09-25, Nordlöw <per.nordlow@gmail.com> wrote:
> Has any body any reflections, ideas or even code snippets that could
> be used to implement a regular expression parser in Emacs-Lisp?
> My highest prio is supporting emacs-style regexps.

There is one cperl-mode.el.  But IIRC it might be inlined, not in a
separate function...  Hmm, maybe it IS separated - I got conflicting
memories of that...

Hope this helps,
Ilya