The problem with trying to do this is the length to consider a
mismatch. If you wanted the mismatch to be considered up to
the next match, you could do something like this:
/(?!#{re}).*?(?=#{re}|$)/
or
/((?!#{re}).)*/
I don't see any practical application for doing something like
this. Is this just a academic question?
···
--- Harry Ohlsen <Harry_Ohlsen@hyperion.com> wrote:
A colleague of mine just asked me whether it was possible to
invert an
arbitrary regular expression. Ie, create a new regular
expression that
matches whatever the original *didn't*.It seems like quite a difficult problem to me, but maybe I'm
just not
looking at it the right way.Obviously simple cases are easy. Eg
re = /[a-z]/
inverse = /[^a-z]/However, I think it would be much harder for arbitrary cases.
Eg, how
would one automatically invert something like the following/<[^<>]*id="!?(region8-).*?>/
Note that I'm not talking about finding lines that don't
contain the
pattern (a la "grep -v"); I'm talking about finding all the
occurrences
within a single line that don't match it.Inquisitively yours,
Harry O.
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