my %code_cache;
while (<>) {
   my $code=$code_cache{$_};
   unless ($code) {
      my @actions=parse_to_actions($_);
      $code=eval "sub { @actions }" 
               or die "$@ while evaling actions @actions ";  
      $code_cache{$_}=$code;
   }
   $code->();
}

##</code><code>##

use Memoize;

sub parse_to_actions {
  return eval "sub { @lines_of_code }" or die $@;
}

memoize("parse_to_actions");
while (<>) {
  #Parse and generate. Memoize caches.
  parse_to_actions($_)->($_); # pass the line to the generated sub 
                              # just in case it gets smart
}