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

my $str = 'abacadabra';
my @matches;
push @matches, [ map { substr $str, $-[$_], $+[$_]-$-[$_] } 1..$#+ ]
    while $str =~ /([ac])([bd])/g;

print Dumper \@matches;