RE: About Constructions rules

Subject: RE: About Constructions rules
From: Avi Kivity <Avi@xxxxxxxxxxxxx>
Date: Fri, 16 Jul 1999 00:27:16 +0300
On Friday, July 16, 1999 00:09, Brandon Ibach [SMTP:bibach@xxxxxxxxxxxxxx]
wrote:
>    Yes, the query is executed just once to generate the "target" node
> list, but Chris is right is saying that *every* node in the grove
> would have to be tested against it.  That's every single character,
> every attribute assignment, etc.  This brings up the problem of
> calling Jade's bluff on the "each character is a separate node" trick.
>    Still, given that node lists are opaque (meaning that the processor
> can represent them however it wants to), it should be possible to
> implement the checks for node membership relatively efficiently.  For
> instance, a smart processor should be able to figure out if a query
> expression would exclude character nodes entirely, and thus it
> wouldn't even have to check them.  This is, of course, a very
> simplistic example, but you can see the possibilities.
>    In short, I think Chris has a legitimate concern, but that it can
> be addressed without extreme difficulty (using methods that are
> probably already being used elsewhere in Jade).
> 

No no no. A few examples:

(query (empty-node-list) (...)) ;no nodes examined or processed
(query (select-elements yoyo (subtree) (...)) ; all *element* nodes
examined, only yoyos processed
(query (search-for-the-letter-s (subtree)) (highlight-the-s))  ;all nodes
examined (probably), s's processed (s! what a wonderful sound!)

---
"The only words which have meaning are the last ones spoken"



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