sub dequote {
    my $x = $_[0];
    $x =~ s/!(.)/$1/sg;
    return $x;
}

while(<>) {
    chomp;
    my @fields = map dequote($_), /\G((?:[^!;]+|!.)*)(?:;|\z)/sg;
    print "$_ => " . join( '|', @fields ) . "\n";
#     print "$_ => @fields\n";
}