private QueryOption parseOption()

in lib/server-core/src/main/java/org/apache/olingo/server/core/uri/parser/Parser.java [300:403]
100 lines of code
28 McCabe index (conditional complexity)

  private QueryOption parseOption(final String optionName, final String optionValue)
      throws UriParserException, UriValidationException {
    if (optionName.startsWith(DOLLAR)) {
      final SystemQueryOptionKind kind = SystemQueryOptionKind.get(optionName);
      if (kind == null) {
        throw new UriParserSyntaxException("Unknown system query option!",
            UriParserSyntaxException.MessageKeys.UNKNOWN_SYSTEM_QUERY_OPTION, optionName);
      }
      SystemQueryOptionImpl systemOption;
      switch (kind) {
      case SEARCH:
        SearchOption searchOption = new SearchParser().parse(optionValue);
        SearchOptionImpl tmp = new SearchOptionImpl();
        tmp.setSearchExpression(searchOption.getSearchExpression());
        systemOption = tmp;
        break;
      case FILTER:
        systemOption = new FilterOptionImpl();
        break;
      case COUNT:
        if ("true".equals(optionValue) || "false".equals(optionValue)) {
          systemOption = new CountOptionImpl().setValue(Boolean.parseBoolean(optionValue));
        } else {
          throw new UriParserSyntaxException("Illegal value of $count option!",
              UriParserSyntaxException.MessageKeys.WRONG_VALUE_FOR_SYSTEM_QUERY_OPTION,
              optionName, optionValue);
        }
        break;
      case ORDERBY:
        systemOption = new OrderByOptionImpl();
        break;
      case SKIP:
        systemOption = new SkipOptionImpl()
            .setValue(ParserHelper.parseNonNegativeInteger(optionName, optionValue, true));
        break;
      case SKIPTOKEN:
        if (optionValue.isEmpty()) {
          throw new UriParserSyntaxException("Illegal value of $skiptoken option!",
              UriParserSyntaxException.MessageKeys.WRONG_VALUE_FOR_SYSTEM_QUERY_OPTION,
              optionName, optionValue);
        }
        systemOption = new SkipTokenOptionImpl().setValue(optionValue);
        break;
      case DELTATOKEN:
        if (optionValue.isEmpty()) {
          throw new UriParserSyntaxException("Illegal value of $deltatoken option!",
              UriParserSyntaxException.MessageKeys.WRONG_VALUE_FOR_SYSTEM_QUERY_OPTION,
              optionName, optionValue);
        }
        systemOption = new DeltaTokenOptionImpl().setValue(optionValue);
        break;
      case TOP:
        systemOption = new TopOptionImpl()
            .setValue(ParserHelper.parseNonNegativeInteger(optionName, optionValue, true));
        break;
      case EXPAND:
        systemOption = new ExpandOptionImpl();
        break;
      case SELECT:
        systemOption = new SelectOptionImpl();
        break;
      case FORMAT:
        if (optionValue.equalsIgnoreCase(JSON)
            || optionValue.equalsIgnoreCase(XML)
            || optionValue.equalsIgnoreCase(ATOM)
            || isFormatSyntaxValid(optionValue)) {
          systemOption = new FormatOptionImpl().setFormat(optionValue);
        } else {
          throw new UriParserSyntaxException("Illegal value of $format option!",
              UriParserSyntaxException.MessageKeys.WRONG_VALUE_FOR_SYSTEM_QUERY_OPTION_FORMAT, optionValue);
        }
        break;
      case ID:
        if (optionValue.isEmpty()) {
          throw new UriParserSyntaxException("Illegal value of $id option!",
              UriParserSyntaxException.MessageKeys.WRONG_VALUE_FOR_SYSTEM_QUERY_OPTION,
              optionName, optionValue);
        }
        systemOption = new IdOptionImpl().setValue(optionValue);
        break;
      case LEVELS:
        throw new UriParserSyntaxException("System query option '$levels' is allowed only inside '$expand'!",
            UriParserSyntaxException.MessageKeys.SYSTEM_QUERY_OPTION_LEVELS_NOT_ALLOWED_HERE);
      case APPLY:
        systemOption = new ApplyOptionImpl();
        break;
      default:
          throw new UriParserSyntaxException("System query option '" + kind + "' is not known!",
              UriParserSyntaxException.MessageKeys.UNKNOWN_SYSTEM_QUERY_OPTION, optionName);
      }
      systemOption.setText(optionValue);
      return systemOption;

    } else if (optionName.startsWith(AT)) {
      // Aliases can only be parsed in the context of their usage, so the value is not checked here.
      return new AliasQueryOptionImpl()
          .setName(optionName)
          .setText(NULL.equals(optionValue) ? null : optionValue);

    } else {
      // The option is a custom query option; the caller can re-use its query option.
      return null;
    }
  }