Convert text string to xml tagging using xsl pt.2

If I have:

<p>This is a @e function that does stuff.</p>
<p>This is also a @e function</p>

and I want to use XSL to surround 'function' with <apiname> tags, example:

<p>This is a <apiname>function</apiname> that does stuff.</p>
<p>This is also a <apiname>function()</apiname></p>

is there a way to do this?

Note that the string 'function' changes and <p> tags can contain more than one <apiname> tag.

I tried:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    exclude-result-prefixes="xs"
    version="2.0">
    
    <xsl:template match="*[contains(text(),'@c ')]">
         <xsl:value-of select="substring-before(text(),'@c ')" />
            <apiname>
                <xsl:value-of select="substring-before(substring-after (., '@c '), ' ')" />
            </apiname>
        <xsl:value-of select="substring-after(., substring-before(substring-after (., '@c '), ' '))" />
    </xsl:template>
</xsl:stylesheet>

but it doesn't work all the time (I'm not sure what determines whether it does or doesn't). It definitely doesn't when '@e function' makes up the last character within the <p> tagging (ex. <p>This is also a @e function</p>)

I'm using DITA Open Toolkit to write Markdown, which is then converted to XML behind the scenes. Then, XSL is applied to the XML to display HTML and other formats. This is why I can't just update the XML from the source.

Use xsl:analyze-string.

Something like

<xsl:template match="p">
  <xsl:analyze-string regex="@e\s+([A-Za-z]+)">
    <xsl:matching-substring>
       <apiname>
         <xsl:value-of select="regex-group(1)"/>
       </apiname>
    </xsl:matching-substring>
    <xsl:non-matching-substring>
       <xsl:value-of select="."/>
    </xsl:non-matching-substring>
  </xsl:analyze-string>
</xsl:template>