Re: [Caml-list] xpath or alternatives

[Stefano Zacchiroli <zack@upsilon.cc>]

On Wed, Sep 30, 2009 at 04:49:37PM +0200, Gerd Stolpmann wrote:
> No. However, there is a little XPath evaluator in SVN:
> https://godirepo.camlcity.org/svn/lib-pxp/trunk/src/pxp-engine/pxp_xpath.ml

Cool, and you have even already implemented all of the XPath 1.0
standard library!

> 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?

If I'm not mistaken, more than a syntax extension that evaluator needs a
parser from concrete syntax to the abstract syntax you've already
implemented. Once you have that, I don't think there is really a need of
any syntax extension, what would be wrong in using it as follows:

  let nodes = xpath_eval ~xpath:(xpath "/foo/bar[2]/@baz") tree in
  let nodes2 = xpath_eval ~expr:"/foo/bar[2]/@baz" in
  ...

we already use regexps this way and is more than handy. Or am I missing
something here?

I don't have energy to volunteer myself, but I duly note that Alain's
old XPath implementation already contains a parser that can be reused
(whereas the lexer should be changed, as already observed; most likely
the lexer should be ported to Ulex).

All in all, it is probably just a matter of integration work (modulo the
limitations of the current evaluator, of course).

Any volunteer? :-)

Cheers.

-- 
Stefano Zacchiroli -o- PhD in Computer Science \ PostDoc @ Univ. Paris 7
zack@{upsilon.cc,pps.jussieu.fr,debian.org} -<>- http://upsilon.cc/zack/
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