my $grammar = q {
			{ my $g = GraphViz->new }
			start: expression /$/ { $return = $g }
			expression: item_right_exp | right_exp | item
			right_exp: operator expression {$return = $g->add_node($item[1]);$g->add_edge($return, $item[2]);}
			item_right_exp: item operator expression {$return = $g->add_node($item[1].'-'.$item[2].'-'.$item[3], label => $item[2]);$g->add_edge($return, $item[1]);$g->add_edge($return, $item[3]);}
			operator: 'AND' | 'OR'
			item: 'NOT' item | multi_word | word {$return = $g->add_node($item[1]);}
			multi_word: '"'word(s)'"' {$return = join(' ', @{$item[2]}); }
			word: /[a-zA-Z\?\*]+/
			
		};