my @values = qw/ a ab. d ef def g|h /;
my ($regex) = map { qr/$_/ }          # 5.
    join '|',                         # 4.
    map {quotemeta}                   # 3.
    sort { length $b <=> length $a }  # 2.
    @values;                          # 1.
print "$regex\n";                     # 6.