XSLT: test if sibling matches list of conditions - xslt

Question

I have a list of conditions, and I want to check if the immediate sibling of an element matches any of those conditions.
If these conditions are simple tag names, this is easy enough.
<xsl:param name="tag-list" select="tokenize('img figure table', '\s+')"/>
<xsl:template match="* | text()">
<xsl:variable name="next-name" select="name(following-sibling::*[1])" />
<xsl:if test="$next-name = $tag-list">
<!-- DoSomething -->
</xsl:if>
</xsl:template>
This template will match any element or text node, and will DoSomething if the immediate following sibling of that node is either <img>, <figure> or <table>.
However, I want to check for more complex conditions. How can I only DoSomething for when the template matches against elements with a sibling with a specific attribute, child or text value? I would prefer to do this with a single <xsl:if>, as this list of sibling conditions could get pretty long.
<xsl:param name="tag-list" select="tokenize('img[#src] figure[text()] table[tbody]', '\s+')"/>
<xsl:template match="* | text()">
<xsl:if test="???">
<!-- DoSomething -->
</xsl:if>
</xsl:template>

Answer 1

Define a function representing your complex condition:
<xsl:function name="my:condition" as="xs:boolean">
<xsl:param name="node" as="node()"/>
... your condition goes here ...
</xsl:function>
and then the test is:
<xsl:if test="following-sibling::*[1][my:condition(.)]">...</xsl:if>
If you want to modularize the condition into separate functions then you can of course do so:
<xsl:function name="my:condition" as="xs:boolean">
<xsl:param name="node" as="node()"/>
<xsl:sequence select="my:first($node) and my:second($node) and..."/>
</xsl:function>
If you want to make the logic a bit more dynamic, so the list of conditions is somehow supplied dynamically, then consider using higher order functions.

Answer 2

If you use XSLT 3 consider whether a static parameter with a shadow attribute allows you to construct the right XPath expression on the fly before stylesheet compilation:
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
exclude-result-prefixes="#all"
version="3.0">
<xsl:param name="tag-list" static="yes" select="tokenize('img[#src] figure[text()] table[tbody]', '\s+')"/>
<xsl:template match="* | text()">
<xsl:if _test="{string-join($tag-list ! ('following-sibling::*[1][self::' || . || ']'), ' | ')}">
<xsl:comment>DoSomething</xsl:comment>
</xsl:if>
<xsl:next-match/>
</xsl:template>
<xsl:mode on-no-match="shallow-copy"/>
</xsl:stylesheet>
At https://xsltfiddle.liberty-development.net/3NSTbf3 that transforms
<root>
<section><span>test</span><img src="foo.jpeg"/></section>
<section>test<table><tbody>...</tbody></table><span>test</span><figure>...</figure></section>
</root>
into
<root>
<section><!--DoSomething--><span>test</span><img src="foo.jpeg"/></section>
<section><!--DoSomething-->test<table><tbody>...</tbody></table><!--DoSomething--><span>test</span><figure>...</figure></section>
</root>
The example is meant to show the use of _test as a shadow attribute, I have intentionally used a different template content as it seems easier to show the result of the code with the identity transformation plus a comment being output where the xsl:if kicks in.