Updated XInclude for Saxon

I’ve just shipped version 5.0.0 of my Saxon XInclude processor in the usual ways. At the level of the stylesheet extension function, this is a drop-in replacement for earlier versions, but it has different behavior in one case (see below) and the internal Java APIs have changed in some backwards-incompatible ways so I bumped the major version number.

What’s different is the way documents that don’t declare a language are handled. Consider:

<doc xmlns:xi="http://www.w3.org/2001/XInclude";
     xml:lang="en">
  <xi:include href="xx.xml" fragid="element(/1/1)"/>
</doc>

where xx.xml is:

<chap><p>Something.</p></chap>

With “language fixup” enabled, previous versions of the extension function would produce:

<doc xmlns:xi="http://www.w3.org/2001/XInclude";
     xml:lang="en">
  <p>Something.</p>
</doc>

But I now think that’s wrong. To see why, consider this example:

<doc xmlns:xi="http://www.w3.org/2001/XInclude";
     xml:lang="en">
  <xi:include href="cy.xml" fragid="element(/1/1)"/>
</doc>

where cy.xml is:

<chap xml:lang="cy"><p>Rhywbeth.</p></chap>

Here, I hope, it’s uncontroversial that the correct result is:

<doc xmlns:xi="http://www.w3.org/2001/XInclude";
     xml:lang="en">
  <p xml:lang="cy">Rhywbeth.</p>
</doc>

The fact that the included elements came from a Welsh language document has to be preserved. I have come to the conclusion that the absence of a language declaration must also be preserved. So the correct result for my first example is

<doc xmlns:xi="http://www.w3.org/2001/XInclude";
     xml:lang="en">
  <p xml:lang="">Something.</p>
</doc>

I think that’s justified by the specification and it’s what version 5.0.0 produces.

I will make the same change to my XProc step(s) when I next publish them (it’s essentially the same code base, but packaged a bit differently).