Regex anchors inside character class

Question

Is it possible to use anchors inside a character class? This doesn't work:

analyze-string('abcd', '[\s^]abcd[\s$]') 

It looks like ^ and $ are treated as literal when inside a character class; however, escaping them (\^, \$) doesn't work either.

I'm trying to use this expression to create word boundaries (\b is not available in XSLT/XQuery), but I would prefer not to use groups ((^|\s)) -- since non-capturing groups aren't available, that means in some scenarios I may end up with a large amount of unneeded capture groups, and that creates a new task of finding the "real" capture groups in the set of unneeded ones.

Answer 1

I believe the answer is no, you can't include ^ and $ as anchors in a [], only as literal characters. (I've wished you could do that before too.)

However, you could concat a space on the front and back of the string, then just look for \s as word boundaries and never mind the anchors. E.g.

analyze-string(concat(' ', 'abcd xyz abcd', ' '), '\sabcd\s')

You may also want + after each \s, but that's a separate issue.

Answer 2

If you're using analyze-string as a function, then presumably you're using a 3.0 implementation of either XSLT or XQuery.

In that case, why do you say "non-capturing groups aren't available"? The XPath Functions and Operators 3.0 spec is explicit that "Non-capturing groups are also recognized. These are indicated by the syntax (?:xxxx)."