Re: Iteration condition...

[radiantmatrix]

I don't know about "shorter, more economical", but perhaps easier to maintain:

## a dispatch table in the form state => CODEref
my %operation = (
   1 => \&do_this,
   0 => \&do_that,
   9 => \&do_another_thing,
);

## a table of transitions in the form pattern => state
my @transition = (
   [ $Start  => 1 ],
   [ $Finish => 0 ],
   [ $Break  => 9 ],
);

my $State = 0;  # or whatever your initial state is.

for my $item (@Input) {

    # check transition conditions in order; if met, change state
    for my $trans (@transition) {
       next unless $item =~ /$trans->[0]/;
       $State = $trans->[1];
       last;
    }

    $operation->{$State}->();  # dereference and execute op for this S
+tate
}

That's a very simple state machine that uses a dispatch table. It's pretty easy to expand: add transitions to the @transition structure, write a sub for each operation and add it to the %operation dispatch table. You don't need to change any other code.

However, if you have a large number of states and/or transitions, using one of the state-machine modules that CountZero references above could be a better choice.