private void advance() throws IOException {
			next = null;
			while((next==null)&&(reader!=null)) {
				final String line = getLine();
				if(line!=null) {
					next = burster.parse(line);
					if(next!=null) {
						if(next.isEmpty()||((!allowPartials)&&(!burster.haveAllFields(next)))) {
							next = null;
						}
					}
				}
			}
		}