Nitpicking: you could remove the x in (?x-s).

I created a small UDL called CommaStruct, and gave it a dummy file of:

https://community.notepad-plus-plus.org/topic/19873/displaying-comma-separated-structures-in-functionlist
STRUCT str1, str2, str3 (…)
    STRUCT aaa, bbb, ccc (…)
STRUCT zzz (…,…,…)

To my functionList.xml, I added:

<association id="CommaStruct"             userDefinedLangName="CommaStruct"    />
<association id="CommaStruct"             ext=".csl"                           />
...
<parser id="CommaStruct" displayName="Comma-based STRUCT" commentExpr="">
  <function
    mainExpr="(?x-s)^\h*STRUCT\h+(\w+)|\G,\h*(\w+)"
  >
    <functionName>
        <nameExpr expr="(?:STRUCT\h+|,\h*)\K\w+" />
    </functionName>
  </function>
</parser>

When I reloaded, I saw:

… so str1,str2,str3, aaa,bbb,ccc, and zzz were all recognized as STRUCT, which is what I understood you wanted.

@MAPJe71 or another FunctionList expert will have to chime in, but from my understanding, when the FunctionList parses the document, each match corresponds to a single entry in the FunctionList display; I don’t know of a way to make it grab multiple from the same line.

However, maybe using an alternation in the regex with \G syntax (which says "start at the end of the previous match), it might be possible. I’ll give it some thought, and if I have a chance to play around with that sometime today (and if no one else has beat me to it), I’ll see if I can come up with something