Hi BaseX team,

I admit, I'm pushing the combinations a bit, but otherwise it wouldn't be any fun... ;-)

I want to call an XSLT stylesheet with Saxon in BaseX. However, the stylesheet should
use an XSLT package. For XSLT packages, I wrote a Saxon initialiser some time ago that
automatically recognises packages in the classpath and configures Saxon so that they
are available.

When embedding it in BaseX, however, I now encounter very strange behaviour when I
execute the stylesheet twice (or more) in the same session. I have reproduced this
in this GitHub project:

https://github.com/nkutsche/basex-saxon-xslt-package-issue

When you run either the shell script basex or basex.bat in the project, the following
happens:

1. The Maven project fetches the necessary dependencies.
- Saxon 12.9 & BaseX 12.2
- xpath-model - the XSLT package I want to use in my XSLTs
(https://github.com/nkutsche/xpath-model/)
- xslt-pkg-manager120 - the Saxon initialiser mentioned above
2. The system property SAXON_INITIALIZER is set to the Saxon initialiser
3. The XQuery script xquer.xq is executed with BaseX:
- this executes test.xsl twice on test.xml with xslt:transform()
- the sequence of both transformation results is the result of the main query.
4. test.xsl uses a function from the XPath model: the XPath expression in test.xml is
parsed into an XML tree.

The second result is then very surprising:

<expr><XPath><Expr Predicate="sequence"><EOF><ExprSingle><Expr Predicate="or"><EOF><Expr Predicate="and"><EOF><ComparisonExpr><Expr Predicate="concat"><EOF><Expr Predicate="range"><EOF><Expr Predicate="additive"><EOF><Expr Predicate="multiplicativ"><EOF><Expr Predicate="union"><EOF><Expr Predicate="intersect-except"><EOF><Expr Predicate="instance-of"><EOF><Expr Predicate="treat-as"><EOF><Expr Predicate="castable"><EOF><Expr Predicate="cast"><EOF><Expr Predicate="arrow"><EOF><Expr Predicate="unary"><EOF><ValueExpr><Expr Predicate="map"><EOF><Expr Predicate="step"><EOF><TOKEN>/</TOKEN></EOF><EOF><Expr Predicate="step"><EOF>[...]

The complete output can also be found here:

https://github.com/nkutsche/basex-saxon-xslt-package-issue/actions/runs/22407282705/job/64870585894#step:4:1823

The first result is as expected. I can hardly explain the second one. Except that the
elements look similar to my intermediate results, but as far as I know, they never occur
in this combination. My only guess is that a few templates in the package suddenly are
no longer matching or no longer match as they should.

Do you have any idea where this might be coming from? I couldn't reproduce the behaviour
when I called Saxon directly twice in a JVM. The problem could still be in Saxon, of
course, but I would first have to reproduce it without BaseX.

Thank you for your help!

Best Regards,
Nico

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