RE: About Constructions rules

[Avi Kivity <Avi@xxxxxxxxxxxxx>]

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.
---
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