code: public void addRuleParserAt(IRuleParser parser, Class<? extends IRuleParser> atParser) {
          int index = getIndexOfClass(ruleParsers, atParser);
          if (index == -1) {
              throw new ParserAddException("parser " + atParser.getSimpleName() + " has not been added");
          }
          ruleParsers.remove(index);
          ruleParsers.add(index, parser);
      }
docs: replace parser
  @param parser
  @param atParser