[XSL-LIST Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Does the count() function require access to the wh
Exactly, this is what I tried to express in my first reply: that count() is not "whitewashing" its argument, and so you can't say "count() is streamable, period". -W On 13/01/2014, Michael Kay <mike@xxxxxxxxxxxx> wrote: > >> >> My first question in other words: Is count( x ) always streamable, no >> matter what x (or a $x or...) is? > > No. Counter-example: count(following-sibling::x) is not streamable. > > More specifically, count(X) is streamable (more specifically, its posture is > grounded) if the posture of X is grounded, climbing, striding, or crawling, > but not if it is roaming. > > Sorry - I know that's a lot of new jargon to absorb on a Monday morning! > > Michael Kay > Saxonica > > >> >> The "positioned" was referring to a quote from Roger, see his post, >> please. >> >> -W >> >> >> On 13/01/2014, Michael Kay <mike@xxxxxxxxxxxx> wrote: >>> >>> On 13 Jan 2014, at 11:59, Wolfgang Laun <wolfgang.laun@xxxxxxxxx> wrote: >>> >>>> With growing insecurity ;-) >>>> >>>> My understanding is that count($x) may be called on the construction >>>> of a sequence which (the construction) is not streamable, and that >>>> calling count(...) on it does not make it streamable. >>>> >>>> Another thing: calling count(...) doesn't require to be positioned >>>> anywhere. >>>> >>> >>> Sorry, but I'm afraid I don't even understand what you're saying/asking >>> here. What do you mean by an expression being positioned? >>> >>> What we are discussing, is in simplified terms, the fact that count(//x) >>> is >>> streamable, but data(//x) is not. Here //x is a "crawling" expression - >>> one >>> that selects nodes which may overlap each other. When an expression >>> returns >>> (potentially) overlapping nodes, the W3C spec says you can apply >>> inspection >>> operations like count() to those nodes, but you cannot apply absorption >>> expressions like data(), because doing so would require buffering. >>> >>> Michael Kay >>> Saxonica
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