Subject: Re: [xsl] Re: . in for From: Dimitre Novatchev <dnovatchev@xxxxxxxxx> Date: Sun, 6 Jan 2002 11:17:43 -0800 (PST) |
--- Jeni Tennison <jeni@xxxxxxxxxxxxxxxx> wrote: > Hi Dimitre, > > >> I imagine that a processor would be able to spot situations where > >> the position() or last() function had been called and only compose > >> the steps that were composable. > > > > It seems to me obviously not so -- I mean the general task of > > spotting ***any*** function in the expression, that could reference > > not only the specific item in the sequence. This includes any > > user-defined functions. > > Yes, you're right of course - the focus at the point at which the > user-defined function is called provides the focus for the body of the > function when it's defined by xsl:function, and that will propagate > through function (and named template) calls from those functions and > so on, making it impractical for the processor to spot. > > I do think that the position of an item in a sequence is going to be > an important piece of information, particularly because items in > sequences can't be sequences themselves. Yet another > usability/optimisability trade-off I suppose. > Yes, and this actually means that a piped 'mapping operator' would not be possible to optimise by the XSLT processor and to convert it into a single map applying a composition of functions. Piped/composed map-s will require big space, proportional to the number of map-s, as compared with the single map operation. Cheers, Dimitre. __________________________________________________ Do You Yahoo!? Send FREE video emails in Yahoo! Mail! http://promo.yahoo.com/videomail/ XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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