Re: [xslt] xpath queries from shell revisted

[Liam R E Quin <liam holoweb net>]

On Wed, 2008-03-05 at 05:58 -0500, Daniel Veillard wrote:
> On Tue, Mar 04, 2008 at 06:56:01PM +0000, Dan Stromberg wrote:
> > 
> > I'm having a little trouble with some basic XPath queries from shell.
> > 
> > I dug up a small handful of what-seem-like simple examples from http://
> > www.w3schools.com/xpath/xpath_syntax.asp and fed them into three xpath 
> > programs (one in C, one in python, one in perl), and got pretty different 
> > results from the 3, a number of which I believe must be incorrect.
> > 
> > I've summarized what I found at:
> > 
> > http://stromberg.dnsalias.org/~dstromberg/xml/xpath-issues.html

I am having a hard time reading that Web page.  The black background
doesn't help :-) but by viewing the source, it looks like the Perl
program is not serializing the results as XML.  The desire to get
pointy-bracket results rather than a string was part of why I wrote
the short libxml wrapper that I did.

> > 
> > Is it perhaps the case that some XPath processing programs don't do 
> > complete xpath?  Are there different levels of xpath implementation 
> > completeness?

$ rpm -qf /usr/bin/xpath
perl-XML-XPath-1.13-8mdv2008.0

It's by Matt Sargeant, and you could do
$ perldoc XML::XPath
(after installing perl-doc if needed)
to learn more.

The findnodes_as_string method might work.

I am not sure what XPath engine is used there; there's
support for libxml in Perl these days, but it's separate,
see
$ perldoc XML::LibXML
for more information.  There's a separate mailing list for
XML on Perl.

It was not clear from your Web page in what way the results differed.
When the /usr/bin/xpath program prints "NODE" it's just not returning
the results in a useful way if you're after a tree.  But it probably
found the same results.

I think my program may take only the first matching node and print it,
I forget.  My expectation was (and remains) that you would look at it
and edit it to meet you needs. Actually I didn't mean to send a copy of
it to the list!

Liam

-- 
Liam Quin - http://www.holoweb.net/~liam/
XML Activity Lead, W3C, http://www.w3.org/People/Quin/
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