Re: [q-lang-users] Avoiding trailing () in CGIs

[<Dr....@t-...>]

Tim Haynes wrote:
> Well, at some future date I would like to be able to read in arbitrary,
> possibly large-ish, XML documents, have them parsed into an accessible
> structure and then be able to perform xpath/xquery queries on them to
> isolate node(s).

Yes, I see. Well it should be possible to write a sablotron wrapper 
which gives access to the internal data structure so that you can carry 
out these queries. Or even map the internal structure into a Q term.

> Oh, ordered dictionaries as well? That would be great. 

I think we're talking about different things here. Q's ordered 
dictionaries are just dictionaries for key values on which an order is 
defined (such as strings, lists or numbers). They are implemented as AVL 
trees. Hashed dictionaries do not require this order, as the key values 
are hashed to give an integer which is used as the actual key in the AVL 
tree, the associated values are buckets (lists) of table elements with 
the same key. Both structures can be nested, of course.

> I was wondering, earlier, what the most appropriate data-structure would be
> for storing such a set of XML nodes, facilitating rapid random access. I'll
> have a look through those sections imminently.

Well, if you need random access to the components of an xml tag, then 
nested dictionaries could work reasonably well. But if sablatron already 
has all the xpath indexing facilities that you need, then it would 
probably be easiest and most efficient to just expose the internal data 
structure which sablotron uses to represent xml, as an external type in 
Q, and provide the necessary access operations in a Q->C module.

Albert

-- 
Dr. Albert Gr"af
Dept. of Music-Informatics, University of Mainz, Germany
Email:  Dr....@t-..., ag...@mu...
WWW:    http://www.musikwissenschaft.uni-mainz.de/~ag