#!/usr/bin/env perl -l

use strict;
use warnings;

my $master = 'comp.hw.';
my @items = qw{
    comp. comp.hw. comp.hw.new. comp.hw.hw. comp.sw.old. muse.hw.new. ancient.
    comp comp.hw comp.hw.new comp.hw.hw comp.sw.old muse.hw.new ancient
};

for my $level (1 .. split /\./, $master, -1) {
    print "Match Level: $level";

    my $re = '^'
           . join('\.' => (split /\./, $master, $level + 1)[0 .. $level - 1]);
    $re .= $re =~ /\.$/ ? '[^.]' : '(?:[.]|$)';
    print "Matching: /$re/";

    print "\t$_" for grep { /$re/ } @items;
}