Re: [xsl] Cheaper to prepend or append an item to a sequence?

[Abel Braaksma <abel.online@xxxxxxxxx>]

Hmm, maybe I misunderstand or we're mixing apples and pears. The way I 
see it, you say "select all @id from whole doc which is not belong to 
meta node" and that means check for each @id whether it belongs to a 
meta-node. You cannot do that check only once. I don't see a difference 
between your and my analysis.


On 22-2-2011 20:51, wQ^ESLAW sEDOW wrote:
> nope... select all @id from whole doc which is not belong to meta node
> - result ia same for every node
>
> 2011/2/22 Abel Braaksma<abel.online@xxxxxxxxx>:
> > wQ^ESLAW,
> >
> > Actually, it _is_ dependent on the current node. //@id gets all @id nodes in
> > the document. The next "[..]" means "filter these nodes by the following
> > expression". That expression is a node-test: "not(ancestor::meta)", which is
> > applied to the _current_ node (the current @id-node).
> >
> > That doesn't mean that a processor cannot optimize that, but in this case
> > that might proof futile: no single element can contain multiple attributes
> > with the same name. Hence the processor will have to test the predicate for
> > each and every found id-attribute.
> >
> > In short: no, it cannot be calculated only once.
> >
> > Kind regards,
> > Abel Braaksm
> >
> >
> > On 22-2-2011 20:26, wQ^ESLAW sEDOW wrote:
> > > @id = //@id except (@id, //meta//@id) - yep... good idea
> > >
> > > but i think that even //@id[not(ancestor::meta)] should be calculated
> > > only once since it not depend from current node - is not it? is
> > > optimizer capable to recognize context dependant from context
> > > independant XPath fragments inside predicate and calculate independant
> > > fragments only once instead calculating it every time for each node?