I am new to Parse::RecDescent and I have a question. I have downloaded some samples and they work well. Here is the grammar from one of the samples I have downloaded.

my $grammar = <<'_EOGRAMMAR_';


   # Terminals (macros that can't expand further)
   #


   OP       : m([-+*/%])      # Mathematical operators
   INTEGER  : /[-+]?\d+/      # Signed integers
   VARIABLE : /\w[a-z0-9_]*/i # Variable


   expression : INTEGER OP expression
              { return main::expression(@item) }
              | VARIABLE OP expression
              { return main::expression(@item) }
              | INTEGER
              | VARIABLE
              { return $main::VARIABLE{$item{VARIABLE}} }


   print_instruction  : /print/i expression
                      { print $item{expression}."\n" }
   assign_instruction : VARIABLE "=" expression
                      { $main::VARIABLE{$item{VARIABLE}} = $item{expre
+ssion} }


   instruction : print_instruction
               | assign_instruction


   startrule: instruction(s /;/)


_EOGRAMMAR_
[download]

Now what I want to do is put the calls to $parser->startrule() inside a loop so that I can use it kind of like a command shell. When I ran my perl script I noticed that if there were some extra characters at the end of the buffer that were preceeded by whitespace the parse was succesfull eg. print a a How can I make sure that the call to $parser->startrule() will fail if there are extra characters at the end of the buffer?