Rate brute_force        mwah     grinder
brute_force  125/s          --        -25%        -92%
mwah         167/s         33%          --        -89%
grinder     1520/s       1114%        812%          --

##</code><code>##

              Rate        mwah brute_force     grinder
mwah         156/s          --        -32%        -87%
brute_force  229/s         47%          --        -81%
grinder     1181/s        659%        416%          --

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;
use Benchmark qw(:all);


my $grinder = sub {
	for (0 .. 1000){
		if ("$_" =~ m/^(?:2(?:[6-9]|5[0-5]?|[0-4]\d?)?|[3-9]\d?|1(?:\d\d?)?|0)$/){
			if ($_ > 255){
				print "Fails for $_\n";
			} 
		} else {
			if ($_ < 255){
				print "Fails for $_\n";
			}
		}
	}
};

my $mwah = sub {
	my $re = qr{
            ((?>\d+))            # what to capture, don't backtrack: (+?> )
            (??{
                $1<255           # what is looked for
                ? ''             # if yes, let the regex succeed
                : '(?!)'         # if no, let the regex bail
            }) 
          }x;
	for (0 .. 1000){
		if ("$_" =~ m/^$re$/){
			if ($_ > 255){
				print "Fails for $_\n";
			} 
		} else {
			if ($_ < 255){
				print "Fails for $_\n";
			}
		}
	}
};

my $bruteforce = sub {
	my $re = join '|', 0 .. 255;
#	print $re, "\n";
	for (0 .. 1000){
		if ("$_" =~ m{^(?:$re)$}){
			if ($_ > 255){
				print "Brute force Fails for $_\n";
			} 
		} else {
			if ($_ < 255){
				print "Brute force Fails for $_\n";
			}
		}
	}
};

cmpthese(-3, {
		grinder		=> $grinder,
		mwah		=> $mwah,
		brute_force	=> $bruteforce,
		});