Now I know why a variable in a programming language must not start with a digit but ok, here is my problem: An ID may start with a digit, so without my FLOATorID token, a Number like 12e12 is ok, but 12e12e12 results in a 12e12 float and an e12 ID what is wrong. I solved it, but I`m not happy with my solution, there has to be a better one. Here is my small lexer without tokens:

			

			options {
			

			k=2;
			

			charVocabulary='u0000'..'u007F'; //allow ACSII Chars
			

			testLiterals=false;
			

			}
			

			

			Tokens {...}
			

			Basic Types like '.' & '='
			

			

			//Whitespace
			

			WS :
			

			( ' '
			

			| 'f'
			

			| ' '
			

			){_ttype = Token.SKIP;};
			

			

			//Newline
			

			NL
			

			: '
			

			' '
			

			'  {newline();}   // Windows/Dos
			

			| '
			

			'  {newline();}  // UNIX
			

			| '
			

			'  {newline();}  // Mac
			

			

			//Single Line Comment
			

			SL_COMMENT : (options {warnWhenFollowAmbig=false;}
			

			: "//" (~('
			

			'|'
			

			'))* {$setType(Token.SKIP);}
			

			

			FLOATorID : (FLOAT ID)=> FLOAT ID {$setType(ID);}
			

			| (INT '.')=> INT ('.' INT)?  ('e' INT)?  {$setType(FLOAT);}
			

			| (INT 'e')=> INT ('e' INT)? {$setType(FLOAT);}
			

			|  INT {$setType(INT);};
			

			

			// Floating Number
			

			FLOAT :
			

			(INT '.')=> INT ('.' INT)?  ('e' INT)?
			

			| (INT 'e')=> INT ('e' INT)?
			

			|  INT {$setType(INT);};
			

			

			//Integer
			

			INT : ('+'|'-')? ('0'..'9')+;
			

			

			//String
			

			ID options {testLiterals=true;} :
			

			( 'a'..'z' | 'A'..'Z' | '0'..'9' | '_' | '-' | '+' | '/' | '?' | '%' | ':' | '
			<' | '>' | '[' | ']')+;