Re: xpath processing brain dead

From: James Pye <lists(at)jwp(dot)name>
To: Andrew Dunstan <andrew(at)dunslane(dot)net>
Cc: Peter Eisentraut <peter_e(at)gmx(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Nikolay Samokhvalov <samokhvalov(at)gmail(dot)com>
Subject: Re: xpath processing brain dead
Date: 2009-02-28 02:19:51
Views: Raw Message | Whole Thread | Download mbox | Resend email
Lists: pgsql-hackers

On Feb 26, 2009, at 7:03 PM, Andrew Dunstan wrote:
> can you point me at any call in libxml2 which will evaluate an xpath
> expression in the context of a nodeset instead of a document?

No, I can't. node-sets are XPath objects not xmlNode objects, so I
don't think it would be as simple as modifying:

xml.c:xpath() {
xpathctx->node = xmlDocGetRootElement(doc);

with the result of xmlXPathNewNodeSet..

[snip other questions]

My *guess* would be that if we were to use a node-set instead, we'd
still have to prefix the XPath query. In this case, with a function
call to an xpath extension function that creates the NodeSet from the
content fragment(s?) of the document created by xml_parse(ie, more or
less, a re-implementation of exsl:node-set() tailored for our use-
case). Well, that or force the user to call it explicitly. Possible or
not--wrt using a content fragment/document as the context node, I find
this less desirable than the current mangling, so I'm becoming quite
indifferent. :)

In response to


Browse pgsql-hackers by date

  From Date Subject
Next Message Tom Lane 2009-02-28 02:35:34 Re: add_path optimization
Previous Message Tom Lane 2009-02-27 23:39:38 Re: add_path optimization