Improve Numeric Parsing Algorithm as similar shown in the followings

[ferhaterata]

NUMBER
          '-'? INT'.'INT EXP? //1.35,1.35E-9,0.3,-4.5
	| '-'? INT EXP //1e10-3e4
	| '-'? INT //-3,45
	;

	fragment INT: '0'|[1-9][0-9]*;  //noleadingzeros
	fragment EXP: [Ee][+\-]? INT;

[ferhaterata]

http://developers-club.com/posts/259691/