anchor.diff:  	;
   
   primary_expr
  -	: NUM
  +	: num
   	| FLOATNUM
   //	| TEMP
   	| REG_ID
  
positive.code: postfix_suffix
  	: (AT) => AT LSQUARE exp COLON exp RSQUARE
  	| (S_E) => S_E
  	| (LCURLY NUM RCURLY) => LCURLY NUM RCURLY
  	;
  
  lookup_expr
  
negative.code: 	| LPAREN exp RPAREN
  	| LSQUARE exp QUEST exp COLON exp RSQUARE
  	| "addr" LPAREN exp RPAREN
  //	| conv_func LPAREN num COMMA num COMMA exp RPAREN
  //	| transcend LPAREN exp RPAREN
  	| NAME LPAREN exp_list RPAREN
  	| NAME LSQUARE NAME RSQUARE
  	;
  
  