anchor.diff:  MUL			: '*';
   DIV			: '/';
   MOD         : '%';
  +QUESTION	: '?';
  +COLON		: ':';
   EQUAL		: '==';
   LE			: '<=';
   GE			: '>=';
  
positive.code: 	|	Literal						# LiteralExpression
  	|	NormalIdentifier			        # NormalIdentifierExpression
  	|	PropertyIdentifier					# PropertyIdentifierExpression
  	|	(NormalIdentifier|PropertyIdentifier) Operator=(INC|DEC)		# PostIncDecExpression
  	|	Operator=(
  			SUB
  
negative.code: 		|	OR
  		)
  		expression	# BinaryExpression
  	|	<assoc=right> expression QUESTION expression COLON expression		# TernaryOpExpression
  	|	<assoc=right> (NormalIdentifier | PropertyIdentifier) 
  		Operator=(
  			ASSIGN
  		|	MUL_ASSIGN 
  