my $re;
$re = qr/((.)(??{ $re })\2|.)/;
my $s = 'abcdegedfc';
foreach my $i (0 .. length($s) - 1) {
    local $\ = "\n";  # add newline to print
	substr($s, $i) =~ /^$re/ and print $1;
}

##</code><code>##

my $s = 'abcdegedfc';
foreach my $i (0 .. length($s) - 1) {
    local $\ = "\n";  # add newline to print
    substr($s, $i) =~ /((.*).?(??{ quotemeta reverse $2 }))/
      and print $1;
}