use Parse::RecDescent;

my $grammar = <<'__EOI__';
parse: {
   # Create error message.
   my $msg = 'FOO!';

   # Create error.
   push(@{$thisparser->{errors}}, [ $msg, $thisline ])
      unless $_noactions;

   # Fail the action.
   undef;
}
__EOI__

my $parser = Parse::RecDescent->new($grammar)
or die("Bad grammar\n");

$parser->parse('');