Re: XSL equivalent sought.

[Peter Nilsson <pnidv96@xxxxxxxxxxxxxx>]

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.
> 
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:-)

Regards,
/Peter Nilsson

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