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

my $text = 'XYYYZ';
my @source;
push @{$source[$1 ? 0 : $2 ? 1 : 2]}, $& while $text =~ /(X)|(Y)|(Z)/g;
print Dumper \@source;
__END__
$VAR1 = [
          [
            'X'
          ],
          [
            'Y',
            'Y',
            'Y'
          ],
          [
            'Z'
          ]
        ];