🚀 go-pugleaf

I would like to have a more powerful negation operator.
Currently, regexps allow negation of a signal set of chars.
I would like negation of a whole subexpression.

e.g. abc(def)^ would match a string that starts with
abc but is NOT followed by def.

I think "^" would be unambiguous as a postfix operator.
"^" as beginning-of-line would only be
valid as the first char of a subexpression.
There is possible confusion with [^abc] as negation of a char set,
but such use could be phased out since [abc]^ is equivalent.

Since negation of a regular expression is a regular expression
and all you have to do to a finite state machine is flip
accepting and non-accepting states, this should be trivial.
Why wasnt it done before?

Dan LaLiberte
uiucdcs!liberte
liberte@cs.uiuc.edu
liberte%a.cs.uiuc.edu@uiucvmd.bitnet