#! /usr/bin/perl
use Data::Dumper;

$re = "(ab+)";
$input = "uno abb dos ab tres abbb cuatro";
my @splits = split /$re/, $input;
print "splits: ", Dumper \@splits;

__END__

splits: $VAR1 = [
          'uno ',
          'abb',
          ' dos ',
          'ab',
          ' tres ',
          'abbb',
          ' cuatro'
        ];