An antlr4 grammar application of a C# abstract class which includes only abstract methods and variables

grammar.g4

grammar AbstractClass;

prog              :   abstractclass;

abstractclass     :   visibility abstr clas CLASSNAME OPEN_BRACKET statement+ CLOSE_BRACKET;

visibility        :   ('public'|'protected'|'internal'|'private');

abstr             :   'abstract';
clas              :   'class';
CLASSNAME         :   AlphaNum+;  
OPEN_BRACKET      :   '{';
CLOSE_BRACKET     :   '}';

statement         :   variable | (normal_func | abstr_func);

variable	  :   visibility type VARIABLENAME;

normal_func       :   visibility type FUNCTIONNAME;
abstr_func        :   visibility abstr type FUNCTIONNAME;

type 		  :   ('bool'|'byte'|'sbyte'|'char'|'decimal'|'double'|'float'|'int'|
			'uint'|'long'|'ulong'|'object'|'short'|'ushort'|'string'|'void');

FUNCTIONNAME	  :   (AlphaNum+'();');
VARIABLENAME	  :   (AlphaNum_LetterFirst+';');

fragment AlphaNum :   [a-zA-Z0-9];
fragment AlphaNum_LetterFirst : ([a-zA-Z]AlphaNum+);

WS                :   [ \t\r\n]+ -> skip ;