Re: XML tools for Octave

[Bill Denney]

On Thu, 29 Jun 2006, Andy Adler wrote:

> On Thu, 29 Jun 2006, Bill Denney wrote:
>
> > Andy Adler wrote:
> > > I'm trying to write this. My idea is that XML like this
> > > <a b="c" d="e"> text <f g="h"/> more text <f>data</f> </a>
> >
> > Shouldn't it parse as something more like
> >
> > v.a.ATTS.b = "c"
> > v.a.ATTS.d = "e"
> > v.a.CHILD{1} = " text "
> > v.a.CHILD{2}.f.ATTS.g => "h"
> > v.a.CHILD{3} = " more text  "
> > v.a.CHILD{4}.f.CHILD{1}   => "data"
>
> My concern is that this output makes writing software to parse the xml 
> output really frustrating - you need to loop through the CHILD vectors 
> to find what you're looking for. This would result in people taking 
> shortcuts that make the code fragile.

But not doing it this way would make an incorrect representation for 
nested structures: what about just parsing xhtml like
<p>abcd <i>efg</i> jklm</p>

would turn into

v.p.TEXT = 'abcd  jklm';
v.p.i.TEXT = 'efg';

which would not reverse correctly because all of these could turn into the 
above:
<p>abcd<i>efg</i>  jklm</p>
<p><i>efg</i>abcd  jklm</p>
<p>abcd  jklm<i>efg</i></p>
...

To me, it should be a reversible transformation.  Also, without keeping 
the order, you would lose the ability to do full XSLT interpretation (what 
do you do about sibling commands).

> This is actually a big debate in the XML semantics community - the fact 
> that XML does not map easily to data structures.

I realize that it doesn't map easily, but it should map reversibly.

> The other issue is that XML allows tag names to be full unicode,
> but octave will only allow [0-9A-Za-z_] characters for structs.
> I'm not sure how to deal with this, but I want to keep a simple
> output format.

That's a pretty big challenge.  The only way I can think of getting around 
this is with a .name field, but that's a very dirty solution.

Bill

--
"Now we have to fight fire with marshmallows!" -- Leslie, _Toys_