my $regex = join '|', qw( red green blue );
foreach my $line ( @lines ) {
    next if $line !~ $regex;
}
[download]

Update: toolic pointed out that the conditions were different for the different colors. A better version would be:

my $negative_regex = join '|', qw( red blue );
my $positive_regex = join '|', qw( green );
foreach my $line ( @lines ) {
    next if $line =~ $positive_regex || $line !~ $negative_regex;
}
[download]

thanks Dragonchild, this looks like good solution.

Didn't realize you can do that w/ regex
Just wanted to add that, OP should be using below as well.


next unless $line =~ $regex;
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s/should/could/;

That's a matter of personal preference.
In PBP, TheDamian recommends avoiding the use of unless. Mainly because statements can very quickly become quite difficult to read if you start extending them and adding multiple conditions.

I tend to agree with this view, but as I say - it's really a matter of personal preference.

Cheers,
Darren :)

The stated problem is not exactly regexp friendly ;-) (to be solved in a single expression), as has been stated by others.

You are looking for a combination of conditions, a problem which might be solved better per parser or similar stuff.

BTW, you can set conditions during the regexp run and jump on the result afterwards. This might be handy if you have several conditions which depend linearly on the input data, sth. like:

 ...
 our $c;
 my $regex = qr{  red   (?{$c|=4})  
                | green (?{$c|=2})
                | blue  (?{$c|=1})
             }x;

 foreach my $line (@lines) {
   $c = 0;   
   next if () = $line =~ /$regex/g, $c != 5;    # bail on: !(red && bl
+ue) | green

   # do something here, got red/blue combo
   
 }
[download]

Regards

mwa