[ssax-sxml] Re: How to get the namespace declarations?

[<ol...@po...>]

Hello!

> > I have just added an example file into the SSAX CVS repository:
> > 		SSAX/examples/daml-parse-unparse.scm

> Sure?  Which cvs repository?  Not the sourceforge one, just checked.

Hmm. Indeed. I distinctly remember committing the code. I did it
again, and now it's definitely there: 

http://cvs.sf.net/cgi-bin/viewcvs.cgi/ssax/SSAX/examples/daml-parse-unparse.scm

The code traverses the SXML tree twice: once to design the translation
from SXML names to XML names and find out about all the namespaces; On
the second traversal, the code emits XML. It is actually possible to
do everything in only one pass. The latter would require a different
traversal combinator (accum-pre-post-order rather than
pre-post-order). Besides, it was past midnight already when I wrote
the code, so I chose the easy way out.

	I have just noticed that I used a match-case special form,
which is Bigloo specific:
	http://www-sop.inria.fr/mimosa/fp/Bigloo/doc/bigloo-6.html#pg1676

I believe many other systems have something similar (DrScheme, for
example). match-case has a distinct feature: non-linear patterns. I
don't use that feature however. Finally,

http://cvs.sf.net/cgi-bin/viewcvs.cgi/ssax/SSAX/examples/pull-punct-sxml.scm

defines a somewhat similar (but unoptimized) pattern matcher and the
corresponding special binding form. However ungainly, the latter
matcher can do what Bigloo's match-case can do. The latter matcher
should run on any R5RS Scheme.

> My requirements can be relaxed to
> (lambda (str)
>   (string=? (xml-format (xml-parse (xml-format (xml-parse str))))
>             (xml-format (xml-parse str))))

> => #t for any string str.

which is, 
	UNPARSE . PARSE . UNPARSE . PARSE === UNPARSE . PARSE

The property above can be derived from the invariant of unparsing I
claimed earlier,
	PARSE . UNPARSE . PARSE === PARSE

by left-multiplying by 'UNPARSE'. That is, I do believe your
requirements will be satisfied.

> <offtopic>
> Hey, what are you doing with agents?
> </offtopic>
... described in the next message ;)

	Cheers,
	Oleg