RE: XSL equivalent sought.

["Didier PH Martin" <martind@xxxxxxxxxxxxx>]

Hi Peter,

Peter said:
But wouldn't it be possible to implement this as a function in terms of
the existing SDQL? I don't know XPath very well, but to me it seems
possible, since we can parse strings using the EL and SDQL gives us the
whole grove. IMO this should be tried before the real work on DSSSL-2
starts.

Didier says:
The construct already showed are SDQL constructs. see below
>
> DSSSL1 expression: (example 1)
> 	(process-node-list (select-elements
>                              (descendants (current-root))
>                              '(FRONTMATTER DATE)))
> DSSSL1 expression: (example 2)
> (sgml-root-element) or something similar, defined as:
>
> (define (sgml-root-element #!optional (grove-node (current-node)))
>   (node-property 'document-element (node-property 'grove-root
grove-node)))
> In this case the equivalent of an absolute positioning to the root
expressed
> by XPath by "/".
>

Now compare this to:
> XPath expression:
> "/frontmatter/date"/>

However, if anyone can create a SDQL construct which is as economical, terse
and relatively easy to learn (this last attribute, is, however, very
subjective), I am all ears and eyes. So, let's see if we can have a SDQL
construct as economical as :

"/frontmatter/date"

I'll remain silent and let the others do the exercise. I already invested so
many hours on this issue.

So the goal is: find the most economical SDQL construct for "from the root,
go to the element date which is itself child of frontmatter". The result of
the query is an element node. With a string based expression like XPath (I
do not sell XPath here, let's just have a thread of reflection about the
pros and cons of string based expressions for GROVE querying).

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.

Other question: What are the different ways to reach a GROVE's element (list
different GROVE access languages).

OK, back to the cavern and go back work :-)

Have a good day
Didier PH Martin
mailto:martind@xxxxxxxxxxxxx
http://www.netfolder.com


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