Am 09.05.2019 um 21:42 schrieb Manuel Souto Pico terminolator@xxxxxxxxx:

@Martin, your example works really well. I had to edit the expression,
as in my real files sometimes they have used lists instead of
linebreaks:

<xsl:param name="lb"
as="xs:string">&lt;/?(li|ul|br)\s*/?&gt;</xsl:param>

However, I can see what I would also need to split at the end of
sentences when there's no escaped tag but just final punctuation. To
avoid the transformation eating the punctuation, I have tried with a
lookbehind assertion but it seems it's not supported:

<xsl:param name="lb"
as="xs:string">(?<=[.!?])\s|&lt;/?(li|ul|br)\s*/?&gt;</xsl:param>

Any ideas?

In general, if there is markup, it might be better to try to parse it,
in your initial sample you seemed to have simple HTML empty element
syntax with <br> elements, now with the adapted regular expression it
seems you expect opening and closing tags.

If you know the escaped markup is an XML fragment then I would try to
parse it with the "parse-xml-fragment" function, if it is HTML, then I
would look into using David Carlisle's HTML parser implementation done
in pure XSLT 2 or use an extension function like the commercial editions
of Saxon offer.

After parsing, you can then apply normal templates or grouping
constructs.

An adaption of the previous suggestion, but now with escaped XML syntax
in the sample input, to then use parse-xml-fragment, is at

B  <xsl:template match="tu">
B B B B B  <xsl:variable name="split">
B B B B B B B B B  <xsl:apply-templates mode="split"/>
B B B B B  </xsl:variable>
B B B B B  <xsl:for-each-group select="$split/tuv/seg" group-by="position()
mod count($split/tuv[1]/seg)">
B B B B B B B B B  <tu tuid="{position()}">
B B B B B B B B B B B B B  <xsl:apply-templates
select="current-group()/snapshot()/.."/>
B B B B B B B B B  </tu>
B B B B B  </xsl:for-each-group>
B  </xsl:template>

B  <xsl:template match="seg" expand-text="yes" mode="split">
B B B B B  <xsl:for-each-group select="parse-xml-fragment(.)/node()"
group-ending-with="br">
B B B B B B B B B  <seg>{.}</seg>
B B B B B  </xsl:for-each-group>
B  </xsl:template>

For HTML parsing you would need to use an extension or David Carlisle's
HTML parser available on Github, but the approach then is the same. Of
course handling different elements like various list constructs needs
more code but once you have a tree you can process the "normal" XSLT way
you can write more templates and/or more modes for various processing
steps to address more complex input structures.