Use preceding \K group negatively

Question

Can I use the the preceding \K group negatively? Can I match the bar inside faxbar funbar bobar and bar and omit the bar inside foobar fobar foooooobar? https://regex101.com/r/qR9kD4/5

Regex

fo*\Kbar

String: (- and desired outcome)

foobar       - no match
fobar        - no match
foooooobar   - no match
faxbar       - match 'bar'
funbar       - match 'bar'
bobar        - match 'bar'
bar          - match 'bar'
dontmineidontwanttfooooobematchedaatall  - no match

Basically invert my current matches (apart from dontmineme...). Hoping I just need to add a ! or something!

Answer 1

You can use \K with a Negative Lookahead assertion:

\b(?!fo+)\w*\Kbar

Demo

A simple solution would be to place what you want to ignore on the left side of the alternation and place what you want to match in a capturing group on the right side of the alternation operator.

fo+bar|\w*(bar)