anchor.diff:  	: '{'! NESTED_ACTION '}'! ( '?'! { $setType(SEMPRED) } )?
   	;
   
  +DOT
  +	: '.'
  +	;
  +
   protected
   NESTED_ACTION
       :
  
positive.code: 		( LPAREN! terms RPAREN!
  			{ ## = #(#[APPL,"APPL"], ##) }	
  		)?
  	;
  
  terms
  
negative.code: 	APPL;
  	LIST;
  	ARG;
  	TRANSF;
  }
  
  grammar
  