I 'm testing antlr and there is a problem

			

			exp : 'n' | '0' | '1';
			

		

generate code as

			

			exp : 'n'..'1';
			

		

I don't understand. I want to model 'n' or '1' or '0'

Generated code :

			

			// Grammar.g:158:7: ( 'n' | '0' | '1' )
			

			// Grammar.g:
			

			{
			

			if ( (input.LA(1)>=20 && input.LA(1)
			<=22) ) {
			

			input.consume();
			

			state.errorRecovery=false;
			

			}
			

		

Thanks