XSLT 3.0 xsl:mode on-no-match="shallow-skip" - xslt

Question

I'd like to filter XML elements out of a response with XSLT 3 with Saxon HE 10.6
<!-- https://mvnrepository.com/artifact/net.sf.saxon/Saxon-HE -->
<dependency>
<groupId>net.sf.saxon</groupId>
<artifactId>Saxon-HE</artifactId>
<version>10.6</version>
</dependency>
I saved cases on https://xsltfiddle.liberty-development.net/3MP42Pc and https://xsltfiddle.liberty-development.net/3MP42Pc/1
I was hoping to be able to use
<xsl:mode on-no-match="shallow-skip" />
(that is: skip elements the do not match a filter.)
So I want to copy all elements that match some deeper attribute value
The structure is like a dataset of shoes with a status, appearing like generic items on a bill.
bill.xml
<bill>
<item>
<shoes>
<status>0</status>
</shoes>
</item>
<item>
<shoes>
<status>1</status>
</shoes>
</item>
<item>
<shoes>
<status>2</status>
</shoes>
</item>
</bill>
I want the generic items (of any kind (shoes)) with status=0
(otherwise said: skip items where '*/[status=0'] does not match)
bill.xslt
<xsl:stylesheet version="3.0">
<xsl:mode on-no-match="shallow-skip" />
<xsl:template match="item/*[status=0]"/>
</xsl:stylesheet>
The result would have to be
<bill>
<item>
<shoes><status>0</status></shoes>
</item>
</bill>
Alas, this script finds nothing
But. In the case of
<xsl:mode on-no-match="shallow-copy" />
It finds (as expected) all items that are not status=0
<bill>
<item/>
<item>
<shoes><status>1</status></shoes>
</item>
<item>
<shoes><status>2</status></shoes>
</item>
</bill>
If i use
<xsl:mode on-no-match="deep-copy" />
It finds all of the items (no filtering).
It seems not very logical to me, even though an item element has the context.
I use SAXON HE version 10.6, the only difference in the code with javax.xml.transform is the use of
TransformerFactory factory = new **BasicTransformerFactory**();
Question is how to make an elegant small script that does this: output the whole xml, skipping the items that do not match.

Answer 1

I think you want to use <xsl:mode on-no-match="shallow-copy"/> with <xsl:template match="item[not(*/status = 0)]"/> (or <xsl:template match="item/*[not(status = 0)]"/> if the item elements all need to be copied, only their children need to be filtered)).
I am not sure where you got the idea that <xsl:mode on-no-match="shallow-skip" /> should do unless you explicitly added <xsl:template match="item[*/status = 0]"><xsl:copy-of select="."/></xsl:template>. Even then you would lose the root element.
If you look at https://www.w3.org/TR/xslt-30/#built-in-templates-shallow-skip it says:
The effect of processing a tree using a mode that specifies
on-no-match="shallow-skip" is to drop both the textual content and the
markup from the result document, except where there is an explicit
user-written template rule that dictates otherwise.

Answer 2

To get the result you (apparently) expect, while using:
<xsl:mode on-no-match="shallow-skip" />
as the default, you would have to make your template:
<xsl:template match="*[descendant-or-self::status=0] | status[.=0]/text()">
<xsl:copy>
<xsl:apply-templates/>
</xsl:copy>
</xsl:template>
in order to copy all branches leading to a <status>0</status> leaf in their entirety.
As already noted, it is much simpler to make:
<xsl:mode on-no-match="shallow-copy" />
the default. Then you only need to add:
<xsl:template match="*[not(descendant-or-self::status=0)]"/>
in order to suppress the branches not having a <status>0</status> leaf.

Answer 3

Thanks Martin
So the logic goes a bit further.
the tip to explicitly write the node misses out of the root tag
https://xsltfiddle.liberty-development.net/3MP42Pc/2
so the solution is to use
<xsl:mode on-no-match="shallow-copy"/>
<xsl:template match="item/*[not(status = 0)]"/>
see
https://xsltfiddle.liberty-development.net/3MP42Pc/3
Michael's suggestion with on-no-match="shallow-skip" also works including the root tag, diving into a descendant.
<xsl:template match="*[descendant-or-self::status=0] | status[.=0]/text()">
<xsl:copy>
<xsl:apply-templates/>
</xsl:copy>
</xsl:template>
https://xsltfiddle.liberty-development.net/3MP42Pc/4
The use of descendant-or-self is new to me though