anchor.diff:  simple_arithmetic_expr :
       integer |
       (MINUS)? VAR |
  -    (integer | (MINUS)? VAR) (arithmetic_op (natural_number | VAR))* ;
  +    (integer | (MINUS)? VAR) (binary_op (bit_number | VAR))* ;
   
   //四则运算算术表达式，加括号
   simple_arithmetic_expr2 :
  
positive.code: natural_number : POSITIVE_INT | ZERO;
  //四则运算符
  arithmetic_op : PLUS | MINUS | STAR | SLASH;
  //关系运算符(comparison predicates)
  relation_op : LESS_THAN | LEQ | GREATER_THAN | GEQ | EQUAL | DOUBLE_EQUAL | NEQ;
  
  
negative.code: //变量
  VAR : [A-Z][a-zA-Z0-9_]*;
  
  //指数运算
  EXPONENITIATION : '**';
  //位运算
  BITWISE_AND : '&';
  BITWISE_OR : '?';
  BITWISE_EXCLUSIVE_OR : '^';
  BITWISE_COMPLEMENT : '~';
  //加号
  PLUS : '+';
  //减号、经典否定关键字
  