RE: XSL equivalent sought.

Subject: RE: XSL equivalent sought.
From: "Didier PH Martin" <martind@xxxxxxxxxxxxx>
Date: Sun, 3 Oct 1999 17:06:29 -0400
Hi Peter,

Peter said:
That was exactly what I meant. I thought I was clear enough. This would be
good, since it is portable and you don't need to go into (for example) the
OpenJade C++ to implement it. What you'd need, however, is the
query-construction-rule. This is not necessary for the implementation, but
to get:
(query (q-xpath "/frontmatter/date" (some-sosofo))

If such an implementation would be too inefficient, it would be possible
to replace it with C++ (or whatever the implementation is wirtten in).

Implementing XPath on top of SDQL and the DSSSL EL is a good exercise as
well as something else:-)

Didier says:
If I understand you well, your proposal is to implement a new DSSSL function
(let's call it "q-xpath" for the moment). Its body or implementation would
be SDQL constructs. It would first parse the xpath expression and the
convert it into SDQL expression. Because the Xpath language is very rich,
this function is potentially big and somewhat complex.

Yes indeed this is interesting and provides a new light on the problem. But
we still need the query construct and this requires C++ modification to the
code. Also, this could be a good stress test for SDQL and its ability to
reach as many elements as XPath. The secondary advantage is that this would
simplify object access for DSSSL users. A possible drawback, the possibility
of being slower that an other implementation having this implemented in C++.
However, as a prototype, this sounds good.

Thanks for you interesting point of view Peter,

Cheers
Didier PH Martin
mailto:martind@xxxxxxxxxxxxx
http://www.netfolder.com

-----Original Message-----
From: owner-dssslist@xxxxxxxxxxxxxxxx
[mailto:owner-dssslist@xxxxxxxxxxxxxxxx]On Behalf Of Peter Nilsson
Sent: Sunday, October 03, 1999 7:30 AM
To: dssslist@xxxxxxxxxxxxxxxx
Subject: Re: XSL equivalent sought.


On Sat, 2 Oct 1999, Matthias Clasen wrote:

>
> > As an example, with XPath you would have "/frontmatter/date".
> >
> > So with SDQL you would have? (I won't answer. I already did the
exercise).
> > But be cautious, With this exercise, your expression has to be SDQL
> > compliant (in accordance with Hytime and DSSSL1 specs). However, you are
> > allowed in this exercise to propose SDQL improvements (the beginning of
some
> > improvements - - Hint: James created an alternative language which is
scheme
> > based but is not SDQL, see the DSSSL2 option, you'll find there the
XPath
> > ancestor, you may consider James proposal as a SDQL alternative).
> >
> > And now compare.
> >
> Didier, I think you misunderstood Peter. He proposes to write a little
> parser in DSSSL which would allow you to write something like
>
> (xpath-location "/frontmatter/date")
>
> and have it use the necessary SDQL functions internally to return
> the right node.
>

Regards,
/Peter Nilsson

--
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