Re: GByte Transforms

Hi Jeff,

Comments below.

On Wednesday 02 June 2004 21:40, Jeff Kenton wrote:
> >
> > Ignore the problem, leave to stylesheet writer testing.
>
> Can't do this.  People do the strangest things in stylesheets, as any
> reader of this list knows.  Your job is to take anything a customer might
> throw your way, no matter how weird, and "do the right thing".

Ok. I was really just trying that one on. I think performance would be too 
unpredictable if we did that which is why we could do with some thoughts on 
this.

>
> > Extra smarts in the compiler to warn of the use of potentially non-linear
> > behaviour. E.G. Recursive templates not being tail recursive, nested
> > loop/ template constructions.
> >
> > As above but aided by structural information for better targeting.
>
> Sure, the more diagnostics for the user, the better.  But be prepared for
> users ignoring them, and customers that set things up so that users never
> see the warnings.

That is a rather an obvious drawback of just warning about potential problems, 
although I have always liked the high level of feedback Saxon gives about 
stylesheet issues.

> > Subset XSLT to limit the scope for non-linear transforms.
>
> It often comes down to that.  The other way to look at the problem of
> "streaming" large input files is to analyze the stylesheet and try to
> decide how much of the input you need to keep during processing. For some
> operations, only the current node is necessary.  More often, keeping just
> the path from the root to the current node will work (as another poster
> suggested). Sometimes, you need the entire input tree, and you're not
> really "streaming" anymore.  Consider it a continuum, rather than just a
> binary "can I stream this stylesheet or not" question.

Nice point about it not being a binary choice although I think streamability 
is perhaps only a sub-plot here. I suspect trivially streamable transforms 
may always have a linear performance characteristic by definition but the 
reverse does not hold, i.e. things that a streamable via re-writing or not 
streamable at all may also have linear performance. I will have a closer look 
at that relationship to see if it holds anything we can use.

Thanks,
Kev