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