RE: About Constructions rules

Subject: RE: About Constructions rules
From: Avi Kivity <Avi@xxxxxxxxxxxxx>
Date: Fri, 16 Jul 1999 14:57:55 +0300
On Friday, July 16, 1999 02:57, Matthias Clasen
[SMTP:clasen@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx] wrote:
> > 
> > A (query ...) construction rule operates in the following way:
> > 1. The dsssl engine hands the style-query-expression the grove root. In
> > fact, with both hands - (current-node) and (current-root)
> > 2. The stylesheet (you) now use standard node manipulation to gather
> > nodes
> > into a node-list. The dsssl engine has no say as to the compexity of
> > this.
> > It can be O(1), O(children in toplevel element), O(all elements), O(all
> > nodes), or O(atoms in solar system).
> > 3. The stylesheet (still you) returns the assembled node-list to the
> > dsssl
> > engine. It may be large or small.
> > 4. The dsssl engine feeds the node-list, node by node, to the
> > construct-expression. This is essentially what (map-constructor) does
> > (or
> > will do in 1.2.2). The sosofos keep their separate identities (they are
> > related to their nodes).
> > 5. When a node's turn to be processed comes, if it is in the node-list
> > returned by the q-c-r, the corresponding sosofo is inserted.
> > 
> 
> This is one way to look at it, but don't forget that there may be multiple
> query rules which match the same node. With your algorithm, we would
> construct 20 sosofos and throw 19 of them away later, since only the one
> produced by the most specific query rule would be used.
> 
Sososo's can be lazy, so the cost is one node pointer and one evaluation
context pointer.


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