Re: question on p:directory-list and base-uri()

Hi Norm,
It reminds me of a Bug Report many  years ago (2013 actually). A Bug in
Saxon was suspected. See
https://www.oxygenxml.com/forum/topic9194.html
dont know if your System has Access to very old issues. It would be
interesting to check relationship to the current issue …

Greetings, Frank
Norm Tovey-Walsh <ndw@nwalsh.com> schrieb am Mi. 26. Feb. 2025 um 09:47:

> Hello,
>
> I think I’ve worked out what’s going wrong and a simple fix. There are
> still some interesting wrinkles though.
>
> Given this document and @select="//c:directory/c:directory":
>
> <c:directory xmlns:c="http://www.w3.org/ns/xproc-step"
>              xml:base="file:/tmp/y/"
>              name="y">
>    <c:file xml:base="file" name="file"/>
>    <c:directory xml:base="z/" name="z">
>       <c:file xml:base="file" name="file"/>
>    </c:directory>
> </c:directory>
>
> My implementation uses the select expression to locate the relevant nodes.
> This one:
>
>    <c:directory xml:base="z/" name="z">
>       <c:file xml:base="file" name="file"/>
>    </c:directory>
>
> And then it constructs a document containing that node. It constructs an
> XML document. What’s the base URI of *that* document?
>
> Well, the wrong answer is, the same as its root element. Because that
> gives you a document with the base URI “file:/tmp/y/z/” that has a root
> element with an xml:base attribute of “z/” and bad happens.
>
> (If the root element doesn’t have an xml:base attribute, surely the 99%
> case in general, or it has an xml:base that’s an absolute URI, no problem
> arises.)
>
> One way to resolve this would be to remove the xml:base attribute from the
> root element in this case. If we’d said that from the beginning of XProc
> 1.0, then users would just be living with it. But I think saying it now
> would be pretty hostile.
>
> The only other option (that I can think of) is to change the base URI of
> the *document* so that when the xml:base attribute is applied, the right
> thing happens.
>
> I spent a few minutes pondering all of the complexity involved in taking
> an absolute URI and a relative xml:base and working out how to manipulate
> the absolute URI so that it was what you’d need to start with to get back
> the original when you applied the xml:base. The simple case, and you always
> get the simple case from p:directory-list, is easy. But users can put
> arbitrary values in xml:base attributes.
>
> What do you do to “file:/tmp/y/z/” to make it the “before URI” if the
> xml:base attribute is “./spoon/../../x/y/test/”?
>
> And then it occurred to me that the base URI of the element’s *parent* is
> *necessarily* the right value. The actual base URI of the element in
> question was literally constructed by applying its xml:base attribute value
> to the parent’s base URI.
>
> We’re left with the wrinkle that the base URI of the *XML document* is
> going to be different (is going to be the base URI of the selected
> element’s parent) from the base URI of the document element in this case.
>
> I can imagine that might be a little surprising, but I think it’s
> justified in order to avoid producing utterly the wrong base URI on the
> document element.
>
> I’ve constructed a few tests and I’ve just thought of one more that I
> should write.
>
>                                         Be seeing you,
>                                           norm
>
> --
> Norm Tovey-Walsh <ndw@nwalsh.com>
> https://norm.tovey-walsh.com/
>
> > To see the world in a grain of sand,/And a heaven in a wildflower,/Hold
> infinity in the palm of your hand/and eternity for an hour.--William Blake
>
>