Re: [xsl] comparing XML document structure

[Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>]

Graydon,

It sounds like you want to infer content models on the fly and then 
validate against them. I can imagine approaches to this, but I doubt 
that I'd trust many algorithms that actually attempted it -- not because 
of XSLT, but because of the problem specifying the problem.

Falling short of the general case there are lots of things you could do:

<xsl:template match="section/*">
  <xsl:variable name="expected-children" 
select="distinct-values(/path/to/specification/section/*/name()"/>
  <xsl:for-each select="*[not(name()=$expected-children)]">
    element <xsl:value-of select="name()"/> not expected here
  </xsl:for-each>
</xsl:template>

It's also possible to index elements by their names plus the names of 
parents (and additional criteria if necessary), if that's a help for 
retrieving things for comparison.

The bottom line is that while what you envision may not be practicable, 
that doesn't mean there aren't useful things that can be done.

But why not use a schema? There are processors such as Trang that can 
infer schemas from documents.

Cheers,
Wendell


On 8/17/2011 5:57 PM, Graydon wrote:
> So I have an XML document which defines the expected semantics of the
> XML output of an SGML-to-XML conversion project as an exemplar; there
> are structures like this, and like these, and like that.
>
> I also have a whole bunch of XML output which ought to conform to that
> semantics.  (This output is the product of a complex, multi-pass, highly
> conditional set of XSLT transforms.)
>
> The desired goal is to be able to programmatically pull the structure,
> at least to the extent of parent-child element pairs, from the
> semantics-defining file, and compare that to each output file in turn.
>
> So if the semantics-defining file gives an example section element,
> which has num, para, and subsection element children, what I want to be
> able to do is create a sequence of axis relationships and test the
> section elements of the output for axis relationships that are not
> members of that sequence.
>
> I'm nearly certain I can't do that, but thought it was much wiser to ask
> and allow for the possibility of a pleasant surprise.
>
> -- Graydon

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Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
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