code: public final hqlParser.constant_return constant() throws RecognitionException {
  		hqlParser.constant_return retval = new hqlParser.constant_return();
  		retval.start = input.LT(1);
  
  		CommonTree root_0 = null;
  
  		Token set301=null;
  
  		CommonTree set301_tree=null;
  
  		try {
  			// hql.g:691:2: ( NUM_INT | NUM_FLOAT | NUM_LONG | NUM_DOUBLE | NUM_DECIMAL | QUOTED_String | NULL | TRUE | FALSE | EMPTY )
  			// hql.g:
  			{
  			root_0 = (CommonTree)adaptor.nil();
  
  
  			set301=input.LT(1);
  			if ( input.LA(1)==EMPTY||input.LA(1)==FALSE||(input.LA(1) >= NULL && input.LA(1) <= NUM_LONG)||input.LA(1)==QUOTED_String||input.LA(1)==TRUE ) {
  				input.consume();
  				adaptor.addChild(root_0, adaptor.create(set301));
  				state.errorRecovery=false;
  			}
  			else {
  				MismatchedSetException mse = new MismatchedSetException(null,input);
  				throw mse;
  			}
  			}
  
  			retval.stop = input.LT(-1);
  
  			retval.tree = (CommonTree)adaptor.rulePostProcessing(root_0);
  			adaptor.setTokenBoundaries(retval.tree, retval.start, retval.stop);
  
  		}
  		catch (RecognitionException re) {
  			reportError(re);
  			recover(input,re);
  			retval.tree = (CommonTree)adaptor.errorNode(input, retval.start, input.LT(-1), re);
  		}
  		finally {
  			// do for sure before leaving
  		}
  		return retval;
  	}
docs: hql.g:690:1: constant : ( NUM_INT | NUM_FLOAT | NUM_LONG | NUM_DOUBLE | NUM_DECIMAL | QUOTED_String | NULL | TRUE | FALSE | EMPTY );