my $last_state=''; 

  while (my $line= <DATA>) { 
    chomp $line; 
    next unless ($line); 
    if (substr($line,0,1) eq '+') {
      # if line starts with a plus use last_state to process 
      process($last_state,substr($line,1));
      } 
    else { 
      # otherwise set last_state and process with it
      my @parts=split(' ',$line,2); 
      $last_state=$parts[0]; 
      process($last_state,$parts[1]);
      } 
  
    } # line 
sub process { 
  my $state=shift; 
  my $input=shift; 
  ... do stuff based on $state and $input ... 
  } # process