Regex applied to Replace function on XSLT 3 not working - xslt

Question

I believe this is a simple problem, I'm trying to apply a Regex to my replace method in a variable in XSLT 3 (I'm also using Saxon (latest version)). I know it is possible to use replace with a regex but it seems that the regex I'm trying to use is wrong, it works in Java but not there on XSLT.
Here is my variable with the replace method:
<xsl:variable name="namePrefix" select="replace(#name, '/(.*_[^_]+)/')" />
I want this variable namePrefix to return me an specific part of the name of my Node (found under the attribute #name), here is an Name Example:
ALBA_MASTER_FIX_Test
I want this regex and replace methode to return to my variable everything before the last _.
I would like to know wheter I'm applying the regex correctly? Or if I should do it in a different way or use a different regex. Thx :)

Answer 1

everything before the last _.
I believe that could be simply:
replace(#name, '_[^_]*$', '')
Alternatively, you could use something like:
<xsl:value-of select="tokenize(#name, '_')[position() lt last()]" separator="_"/>

Answer 2

This works in the very useful xslt3fiddle based upon SaxonJS:
replace(#name, '(.*)_(.*)', '$1')
Can see used in this stylesheet
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="3.0"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
exclude-result-prefixes="#all">
<xsl:output method="xml" indent="yes" />
<xsl:variable name="inputElement" as="element()" >
<input name="ALBA_MASTER_FIX_Test" />
</xsl:variable>
<xsl:template name="xsl:initial-template">
<output value="{replace($inputElement/#name, '(.*)_(.*)', '$1')}" />
</xsl:template>
</xsl:stylesheet>
with output
<output value="ALBA_MASTER_FIX"/>