#ABNF 1.0 utf-8;

language en;
mode voice;
tag-format <semantics/1.0>;
root $command;

$src_shapes =
	object   {$ = -1;} |
	circle   {$ =  0;} |
	square   {$ =  1;} |
	triangle {$ =  2;};

$src_colors =
	red    {$ = 0;} |
	yellow {$ = 1;} |
	blue   {$ = 2;};

$dest_shapes = $src_shapes {$ = $$;};
$dest_colors = $src_colors {$ = $$;};

/*

Just a reminder:
$rule_name = [optional] tokens [the] (user | visitor) can say
  [and] (repeat)<2-4> [of course] you can also
  $reference $<external.gram> files;

$rule_name2 = anything {$ = "this is semantic interpretation tag, which is
  actually ECMAScript";};

*/

// root rule
public $command = change [the]
    [$src_colors  {$.src_color  =  $src_colors;}]
	[$src_shapes  {$.src_shape  =  $src_shapes;}] to [a]
	[$dest_colors {$.dest_color = $dest_colors;}]
	[$dest_shapes {$.dest_shape = $dest_shapes;}];