Subject: RE: [xsl] Re: . in for From: "Michael Kay" <michael.h.kay@xxxxxxxxxxxx> Date: Sun, 6 Jan 2002 19:50:43 -0000 |
> 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. There's a debate going on about whether context should be provided as an implicit parameter to user-defined functions or not. Optimisation is certainly a lot easier if context is *not* retained through the function call: in other words, if the function needs to know position(), it has to be supplied as an explicit argument. In that case it certainly is possible to detect whether an expression uses position() or last(). (This applies equally to XPath 1.0. Saxon currently assumes the worst case: if an expression calls an extension function, then it's assumed to need position() and last().) Mike Kay XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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