Regex - excluding words but with wildcards

Question

May not be possible with one expression but here goes.

txt = 'check from HERE and i need RED but not BLUE'

For the above text I need an expression that will match if 'RED' appears anywhere after 'HERE' but 'BLUE' does not appear anywhere after HERE.

Answer 1

For posterity:

Without regular expressions

txt = 'check from HERE and i need RED but not BLUE'
after_here = txt.split('HERE', 1)[1]
result = red in after_here and blue not in after_here

Regular expression

^.*HERE(?!.*BLUE.*).*RED.*$
#   ^ look after 'HERE'
#           ^ negative lookahead in everything that comes after HEAD for BLUE
#                     ^ look for RED in everything that comes after HEAD

// see https://www.regular-expressions.info/lookaround2.html