want to know if something is a valid NCName? easy! just do
/self::node()[exsldyn:evaluate(concat('not(self::exsldyn:', $thing, ')'))]
XSLT 1.0 + EXSLT is a constant exercise in things you probably weren’t intended to be able to do but nevertheless can
this probably actually needs a touch of hardening (making sure $thing does not contain a '[' or '/', or else you could run into serious issues) but
/self::node()[translate(normalize-space($thing), ' /([,*', '')=string($thing) and exsldyn:evaluate(concat('not(self::exsldyn:', $thing, ')'))]
i think is safe
here is a shell command you can run to test whether the value of MAYBE_NCNAME is an ncname or not; returns exit status 0 if it is and 1 otherwise
printf '%s\n' '<transform xmlns="http://www.w3.org/1999/XSL/Transform" xmlns:exsldyn="http://exslt.org/dynamic" version="1.0"><param name="thing"/><template match="/"><choose><when test="/self::node()[translate(normalize-space($thing), " /([,*", "")=string($thing) and exsldyn:evaluate(concat("not(self::exsldyn:", $thing, ")"))]">ok</when><otherwise>ng</otherwise></choose></template></transform>' | xsltproc --stringparam thing "${MAYBE_NCNAME}" --html --novalid - /dev/null 2>/dev/null | grep -F -q -x 'ok'
this might be the easiest portableish way of doing this and that is a condemnation of the current state of computing on Posix
Posix be like, “ok but suppose someone is developing an operating system which never has to process XML” 🙄
everyone decided to build operating systems around C code and a portable shell and then they standardized that, but everyone agreed on a whole lot of other things also and they decided that wasn’t worth the bother
@Lady yeah, I believe you that it might well be the easiest portablieish way to do this but when i look at the code ... well let's just say that 'easy' isn't the first word that sprang to mind.