You're really not going to find that in a single regex, unless you also include code-blocks as part of your solution, in which case you're back into the realm of full Turing-completeness where it can always be done.

And I don't call it "right non greedy". I think that's where you start thinking that "left non greedy" can exist. I call it "minimal repetitions", which means it doesn't need to really maintain state -- just prefer "match again" over "stop here", or vice versa.

Your hypothetical regex would need a lot of state as it kept searching. It'd also have to search the entire string every time, in a myriad of ways. Can you say slooooooow?

Here's one way you can do it with some extra code: 

my $string = "....";
my $regex = qr/...(...).../; # must have $1 be the thing we're optimiz
+ing to reduce
my @solutions;
while ($string =~ g/(?=$regex)/g) {
  push @solutions, [[@-], [@+]]; # push starts and ends
}
# now walk through the solutions, and pick the one with the minimal sp
+an on $1
# [ code unfinished ]

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-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

In reply to •Re: left-non-greedy regex? by merlyn
in thread left-non-greedy regex? by dash2

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