if ($x and ! $y) {
    ...
}
elsif (!$x and $y) {
    ...
}
else {
    ...
}

##</code><code>##

  1 sub _synch_arrays {
  2     # if the method is called from a token generated by the get_tag() method,
  3     # the returned array reference will be identical to a start or end tag
  4     # token returned by get_token() *except* the first element in the reference
  5     # will not be an identifier like 'S' or 'E'
  6 
  7     my $array_ref = shift;
  8     my $tag_func  = GET_TOKEN;
  9 
 10     unless ( grep { $array_ref->[0] eq $_ } keys %token ) {
 11         # created with get_tag() method, so we need
 12         # to munge the array to match the get_token() array
 13         # After this is called, and before the method returns, you must
 14         # use something like the following:
 15         # shift @$self if $method == GET_TAG;
 16         $tag_func = GET_TAG;
 17         if ( '/' ne substr $array_ref->[0], 0, 1 ) {
 18             unshift @$array_ref, 'S';
 19         }
 20         else {
 21             unshift @$array_ref, 'E';
 22         }
 23     }
 24     return ( $array_ref, $tag_func );
 25 }

##</code><code>##

  1 sub as_is {
  2    my ( $self, $method ) = _synch_arrays( shift );
  3    my $type = $self->[0];
  4    my $text = $self->[ $token{ $type }{ text } ];
  5    shift @$self if $method == GET_TAG;
  6    return $text;
  7 }