Re: RE: Re: . in for

Dimitre,

>> As a point of information, the implementation of "for" expressions
>> in Saxon 7.0 is fully pipelined, so there will never be a need to
>> store intermediate sequences in memory.
>
> We were discussing with Jeni the problem for optimisation if certain
> functions like position() (or any other function, including
> user-defined ones, that uses the result of the inner for as a
> sequence) are used in an outer 'for' and the inner 'for' decreases
> the cardinality of its sequence by producing one or more empty
> sequences (). This is fully described in:
>
> http://aspn.activestate.com/ASPN/Mail/Message/xsl-list/968103
>
> It is interesting to hear your solution -- where were Jeni and I
> wrong?

Not wishing to preempt Mike's reply, but I think that for expressions
as defined don't support the position() function anyway (the focus
stays the same throughout the for expression because range variables
can be used instead), so it isn't a problem there.

Cheers,

Jeni

---
Jeni Tennison
http://www.jenitennison.com/


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