[xsl] Copy-per-default

Subject: [xsl] Copy-per-default
From: Fredrik Bengtsson <Fredrik.Bengtsson@xxxxxxxxxxxx>
Date: Wed, 20 Apr 2011 15:24:54 +0000

I am using FOP trunk to generate PDFs from DocBook documents on the command
line. Fop.bat is doing the XSL transformation, using whatever engine fop uses
(xalan?). I have written the XSLT entirely by myself, i.e. I am not using any
default DocBook transform or similar. The transform is small and under my
strict control.

I am having the problem that the transform does not behave as expected in two
* Contents of nodes are being copied to the output as if there were some kind
of identity transform in effect by default even though I have not written one,
* Matches far down in the document cannot fetch data that existed earlier in
the document, as if select="/x" selected the x post-transform instead of

Imagine a document like this (ignoring namespaces etc for brevity):

    <title>Ch. 2: The chapter</title>
    <titleabbrev>Ch. 2</titleabbrev>

If I have the following transforms in place:

<xsl:template match="/d:book">
  <!-- ignoring root, page-sequence etc for brevity -->
  <xsl:apply-templates />

<xsl:template match="d:chapter">
  <xsl:apply-templates />

<xsl:template match="d:chapter/d:title">
  <fo:block> ... ... </fo:block>

Then for some reason the titleabbrev appears in the output even though I have
not made any rule explicitly matching it. It is caught along with the title
inside the apply-templates under d:chapter. I thought that this would not
happen, unless I really added a matching template of some sort, for example an
identity transform.

I then just for fun tried to add the following template:

<xsl:template match="*" />

That got rid of the offending titleabbrev, BUT it also had the effect of
breaking another template that special-cases the first chapter:

<xsl:template match="d:chapter[1]">
  <xsl:variable name="abbr">
    <xsl:value-of select="/d:book/d:titleabbrev" />
  <!-- note: that selects a node that is higher up in the document -->
  <!-- now do something with $abbr -->

It seems that at that point, book/titleabbrev has already been transformed,
i.e. removed due to the catch-all template above, so $abbr is empty. That
strikes me as extremely strange; should the select not grab nodes from the
original unmodified document? If I remove the catch-all, $abbr is set properly
just as expected.

This is really confusing! And again - I am not using a huge third-party
transform and modifying it, but rather using a really small, custom-written
and strict one under my control.


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