Subject: Re: [xsl] Cheaper to prepend or append an item to a sequence? From: Вячеслав Седов <schematronic@xxxxxxxxx> Date: Tue, 22 Feb 2011 23:06:51 +0300 |
yep... it some kind of recursion - current @id should be compared with all other @id (except @id inside meta element) 22 FEWRALQ 2011G. 23:02 POLXZOWATELX Abel Braaksma <abel.online@xxxxxxxxx> NAPISAL: > 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?
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