Re: [xsl] XSL pattern needed for begin/end elements

Subject: Re: [xsl] XSL pattern needed for begin/end elements
From: Mike Trotman <mike.trotman@xxxxxxxxxxxxx>
Date: Wed, 07 Jul 2004 23:35:08 +0100
Hi Tracy.

I see than John Harsen has already posted an explicit template to suppress text_run from being processed twice.

In XSLT there are default rules that match all elements and text nodes.
The default for these is to process the node and it's children and print the contents of text nodes.

If you don't want this behaviour then you can turn it off by defining your own overriding templates.
<xsl:template match='*'/>
<xsl:template match='text()'/>
<xsl:template match='@*|/'/>

If you do this - then only templates that you specify will be processed,
but you have to supply a processing chain that will reach all the nodes you want.

I gave you the example using 'mode' so that you could see how to decide when to process text_run elements.
So - I should have emphasised the mode attribute.
This also lets you process text_run and other nodes independently of the hyperlink-begin element by using another mode - if you want to,
and to do different processing on them when they are not being processed as part of the hyperlink context.

Tracy Atteberry wrote:


Thanks for your suggestion.  Your template code is much cleaner than
what I had posted (so I used it as an example to clean up my own!) but
unfortunately the behavior remains the same.  That is, the text_run
elements between the hyperlink_(begin/end) elements are processed twice.
Once for the hyperlink then again.

So the output looks something like this:

<HyperLink xlink:href="";>
  Click <b>here.</b>
Click <b>here.</b>

How do we stop the intervening elements from being processed twice?


-----Original Message-----
From: Mike Trotman [mailto:mike.trotman@xxxxxxxxxxxxx] Sent: Wednesday, July 07, 2004 3:09 PM
To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re: [xsl] XSL pattern needed for begin/end elements


I haven't worked through this too carefully - but here is a pseudo-code method that might work in the sibling case.
It is based on the idea of selecting all following nodes for processing based on their next <hyperlink_end> element having matching attributes to the current hyperlink-begin.
(which looks like what you were intending)

<xsl:template match='hyperlink-begin'>
<HyperLink xlink:href="{concat(locator_url/@protocol,'/',locator_url/@host_name)}">
<xsl:apply-templates select='following-sibling::*[following-sibling::hyperlink_end[1][@id=cur
rent()/@end]' mode='INLINK'/>

<xsl:template match='text_run' mode='INLINK'>
<xsl:when test='@emphaisis="bold"'>
<b><xsl:value-of select='.'/></b>
<xsl:value-of select='.'/>

There are other ways of doing the 'INLINK' mode processing - depending on hwo complex it gets.
E.g. - you could have separate templates matching 'text_run[@emphasis]'

You may need an additional template
<xsl:template match='*' mode='INLINE'>
   <xsl:apply-templates/> <!-- or whatever else you want to do -->
</xsl:template> if you need to process non-sibling intervening elements.

I think something close to the above should work.


Tracy Atteberry wrote:


The current project is a demo for something that will eventually be written in C/C++. Then as you say, we can then walk the DOM tree and maintain a separate context stack to help solve the problem.

For now, we can definitely assume that these elements are siblings. In

fact, for most real source documents this will be the case. Given that

assumption, I would love to know the not-too-difficult solution, as this is my immediate problem.

As for the more general case, a hyperlink may in some cases overlap text runs. For example:

<text_run emphasis="bold">Click <hyperlink_begin id="111" end="222">
<locator_url protocol="http" host_name=""/>
<text_run> to download.</text_run>
<hyperlink_end id="222" begin="111"/>

In fact, hyperlinks can overlap paragraphs and other document elements though this is rarely seen in practice.


-----Original Message----- From: Mike Trotman [mailto:mike.trotman@xxxxxxxxxxxxx] Sent: Wednesday, July 07, 2004 1:26 PM To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx Subject: Re: [xsl] XSL pattern needed for begin/end elements

If the begin and end elements are siblings at the same level then the problem is tractable and probably not too difficult to solve.

However if they can occur at different levels then this means that one
of them is enclosed inside an element that excludes the other (I


Can you give any example of a case where the begin and end elements are
not siblings at the same level?
I ask because:
a) I can't picture how this would make sense given the information that

you require them to contain
b) If one of them does occur inside an element that excludes the other
- what would you want to to with the excluded part of this elements

content / tree?
- If you start closing all the parent elements etc (and opening


again to match the orphaned end tags)
  then you are destroying the structure and meaning of the XML data
which XSLT is designed to help preserve.

I.e. if they are not siblings at the same level then the XML data
'structure' is totally inappropriate for XSLT
and the 1st thing you should do is process it using something else.

I have documents like this - and I process them by walking the DOM tree
and maintaining a separate STACK of whatever I consider my current context to be.
(I am doing this to detect overlap between different document layers marked in exactly the way you describe.)

Tracy Atteberry wrote:

Hi all,

I'm looking for an XSL pattern to solve the problem of going from XML
that has separate begin and end elements to one that does not.

Please, please note that I do not control either the source or target
XML formats.  If I did, this would be much easier.

Source XML snip:

<hyperlink_begin id=3D"111" end=3D"222">
<locator_url protocol=3D"http" host_name=3D""/> </hyperlink_begin> <text_run>Click</text_run>
<text_run emphasis=3D"bold">here.</text_run>
<hyperlink_end id=3D"222" begin=3D"111"/>

Target XML example:

<HyperLink xlink:href=3D"";>
 Click <b>here.</b>

In my case I can assume that associated begin and end hyperlink tags
will occur as siblings -- though generally this is not the case and in

fact, this is the reason the begin and end tags are unique elements.

I have a template that /almost/ works so feel free to let me know why
it fails OR suggest a completely different solution.

Current XSL template snip:

<xsl:template match=3D"//hyperlink_begin">
<xsl:variable name=3D"linkUrl">
<xsl:value-of select=3D"locator_url/@protocol"/>
<xsl:value-of select=3D"locator_url/@host_name"/>
<xsl:variable name=3D"endID" select=3D"@end"/>
<xsl:element name=3D"HyperLink">
<xsl:attribute name=3D"xlink:href"><xsl:value-of
<xsl:apply-templates select=3D"(following-sibling::*) except (following-sibling::hyperlink_end[@id=3D$endID]/following-sibling::*)"



This produces the correct hyperlink but the template for text_run
elements gets called twice this way -- once inside the hyperlink, then

again as templates continue to be applied.

Any help would be greatly appreciated. Thanks!

Tracy Atteberry

PS. I'm using Saxon 8

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