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Re: [xsl] attribute value templates in elements fetched from a map?

2020-09-03 12:29:44
I don't think I've fully understood what you're trying to achieve but 
instinctively it feels to me like the kind of problem for which the elegant 
approach is to first generate an XSLT stylesheet, and then execute it.

Michael Kay

On 3 Sep 2020, at 16:55, Martin Honnen martin(_dot_)honnen(_at_)gmx(_dot_)de 
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

Am 03.09.2020 um 16:24 schrieb Graydon graydon(_at_)marost(_dot_)ca 
On Wed, Sep 02, 2020 at 10:27:17PM -0000, Martin Honnen 
martin(_dot_)honnen(_at_)gmx(_dot_)de scripsit:
I don't understand where you use xsl:evaluate and where you bind the
value to $calculated.

Let me try to give less ambiguous context!

I've got a few hundred source elements; these group into a small number of 
structural categories.  (block, table, inline, link, etc.)  That happens via 
map lookup:

<xsl:template match="*[$categoryMap(name()) = 'block']>
...structure markup goes here....
...something has to define the style...

That part works.

Inside the structure markup, there's an element that defines the rendering 
style.  There are many more rendering styles than there are structures, but 
many fewer than input element names; perhaps a hundred.  The rendering style 
is usually but not always a simple mapping between the element name and a 
style name, and I could -- for at least 80% of the cases -- store that in 
the same map as element markup if I went from


So the grouping templates would use

<xsl:template match="*[$categoryMap(name())('groupname') = 'block']>

and the style would use
<xsl:sequence select="$categoryMap(name())('style')"/>

and retrieve the style markup appropriate to this input element name.

This is attractive because I could keep all the details in the map, making 
long term maintenance simpler; the templates and the logic are stable and 
behaviour gets driven from the map, making it easy to add new elements or 
change a style.

The problem is that it isn't always a static style; sometimes other 
information that depends on the input element context is required, such as 
title depth. (title depth = "how many of my ancestors have titles?") This 
means there's extra/different markup in the style definition and a value 
that isn't statically derived from the element name. What I want to do is to 
store the style markup in the map in the same way, and populate it with the 
specific values somehow after I retrieve it.

So far,
- anonymous functions are an awkward and doubtful way to create nested
  elements in the result tree; might as well just call a regular XSLT
  function directly and encapsulate the source-element-to-style mapping
  in that function
- evaluate doesn't get me anything because I can xsl:evaluate XPath, but
  not markup, so this isn't a way to process the elements retrieved from
  the map to populate values
- there isn't any way (that I know of) to say "plunk this block of
  markup into the evaluation context like we called xsl:call-template
  and this markup retrieved from the map is what was in the template we
- there isn't any way (that I know of) to put an attribute value
  template in the element markup in the map and have it evaluated at
  retrieval time.

What I want to know is if I'm missing something, and there's a way to get 
element markup back out of a map and put it into evaluation context without 
having to use transform() and start a whole new process and pass in the 
whole input document for context anyway.

I haven't completely understood it but the third point sounds like you
need fn:transform on dynamically constructed or retrieved code. I know
you ruled that out in your initial post but I am not sure there is a
simpler way.

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