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Date: -- (:)
From: Gerd Stolpmann <gerd@g...>
Subject: Re: [Caml-list] xpath or alternatives

Am Mittwoch, den 30.09.2009, 15:39 +0200 schrieb Stefano Zacchiroli:
> On Mon, Sep 28, 2009 at 01:17:45PM +0100, Richard Jones wrote:
> > I need to do some relatively simple extraction of fields from an XML
> > document.  In Perl I would use xpath, very specifically if $xml was an
> > XML document[1] stored as a string, then:
> > 
> >     my $p = XML::XPath->new (xml => $xml);
> >     my @disks = $p->findnodes ('//devices/disk/source/@dev');
> >     push (@disks, $p->findnodes ('//devices/disk/source/@file'));
> 
> I've just realized that this thread can look a bit ridiculous, at least
> for people used to other languages where XPath implementations can even
> be found in the language standard library (the best solutions we have
> thus far are: a 40-line xml-light solution, the need to use a modified
> version of the OCaml compiler [yes, I know, it is compatible, but still
> ...], Galax with unreachable homepage, ...).
> 
> So, I was wondering, has anybody ever tried to develop an XPath
> implementation on top of, say, PXP? The original announcement page of
> PXP (now archived) mentions "rumors" about people which, back then, were
> developing it. Has anything ever been released?

No. However, there is a little XPath evaluator in SVN:

https://godirepo.camlcity.org/svn/lib-pxp/trunk/src/pxp-engine/pxp_xpath.ml

I have never found the time to complete it, and to add some syntax
extension for painless use. But maybe somebody wants to take this over?

Gerd

> At first glance, it doesn't seem to exist any specific typing problem,
> at least with XPath 1.0, since the PXP node interface is already common
> for all node types. Sure XPath 2.0, when static typing is in use, can be
> better integrated with the language, but that's probably already
> happening in Galax.
> 
> [ Cc-ing the PXP mailing list ]
> 
> Cheers.
> 
-- 
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gerd@gerd-stolpmann.de          http://www.gerd-stolpmann.de
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