Subject: RE: About Constructions rules From: Avi Kivity <Avi@xxxxxxxxxxxxx> Date: Thu, 15 Jul 1999 23:47:36 +0300 |
On Thursday, July 15, 1999 23:31, Chris Maden [SMTP:crism@xxxxxxxxxxx] wrote: [query construction rules] > > But of course, you have to check every node against your list of > queries. With only element construction rules, a very small > percentage of all nodes (usually) are candidates for a given > construction rule. Evaluating every node will hose your performance. > You can compile queries, of course, but with arbitrary possible > expressions, you'll always have potential ratholes. > I don't see why. The standard says: [165] style-query-expression = expression A style-query-expression shall return an object of type node-list. Within a style-query-expression, the current-root and current-node procedures both return the grove root of the grove being processed. This means that the rule is called, at most, once per grove per mode. If any thrashing about is to be done, you have to specify it explicitly. And of course it can be done lazily. --- "The only words which have meaning are the last ones spoken" DSSSList info and archive: http://www.mulberrytech.com/dsssl/dssslist
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