Implementing an extension function that returns result tree fragment

[Erik Rydgren <er...@mandarinen.se>]

Hi all!

 

I’m trying to create an extension function that should return a tree
fragment. The problem is that the returned tree fragment doesn’t
actually reside inside the source document. I must create it on the fly
and return it. To clarify I will show you an example of what I want to
do.

 

<xsl:variable name=”result” select=”aptic:regexp(//text(),
‘^the_row.*data (?P<data1>……) more data (?P<data2>…).*’)”/>

 

After the call I want the $result variable to contain a traversable tree
fragment that looks something like this

<result>

  <row matched=’false’/>

  <row matched=’false’/>

  <row matched=’true’ data1=’the fetched data’ data2=’more fetched
data’/>

  <row matched=’false’/>

</result>


I have all the extension functionality in place. It gets called while
doing a transformation. The regexp works just fine. The problem is that
I can’t create the tree fragment.

First I planned to create the tree fragment inside the source document,
but not actually connecting it to the document. But since the
XalanDocument I get passed to the execute function is read only I can’t
create a single extra element in it. I looked at the
XercesDocumentWrapper for an answer but to my knowledge then I would
have to rebuild the wrapper which is probably a bad idea for two
reasons. It is SLOOOW and furthermore deallocating the wrapper nodes
that are already in cached nodelists and so on is just like bringing a
big gun and shooting myself in the foot.

 

Now I’m looking into creating a new document that contains the result
tree. But the problem with that solution is deallocating it afterwards.
Is there somewhere I can register my new document for destruction when
the transformation is finished? Is there a better way? Is what I’m
trying to do possible at all?

 

Thanks in advance


Erik Rydgren
Software engineer

Aptic AB
Kåsatorpsvägen 5
SE 541 34 SKÖVDE
Sweden

tfn: +46(0)500-416506
fax: +46(0)500-413215
mail:  <ma...@aptic.se> erik.rydgren@aptic.se
site:  <http://www.aptic.se> www.aptic.se

Re: Implementing an extension function that returns result tree fragment

[Joseph Kesselman <ke...@us.ibm.com>]

Use any DOM implementation (EXCEPT the one built into Xalan, which is
deliberately read-only), build your new tree using that, return its root as
the result of your extension function.

______________________________________
Joe Kesselman, IBM Next-Generation Web Technologies: XML, XSL and more.
"The world changed profoundly and unpredictably the day Tim Berners Lee
got bitten by a radioactive spider." -- Rafe Culpin, in r.m.filk