Method parseDateSymbol

base/src/main/java/net/time4j/Duration.java:3781–3809

(
        char c,
        String period,
        int index
    )

    }

    private static CalendarUnit parseDateSymbol(
        char c,
        String period,
        int index
    ) throws ParseException {

        switch (c) {
            case 'I':
                return MILLENNIA;
            case 'C':
                return CENTURIES;
            case 'E':
                return DECADES;
            case 'Y':
                return YEARS;
            case 'Q':
                return QUARTERS;
            case 'M':
                return MONTHS;
            case 'W':
                return WEEKS;
            case 'D':
                return DAYS;
            default:
                throw new ParseException(
                    "Symbol \'" + c + "\' not supported: " + period, index);
        }

    }

    private static ClockUnit parseTimeSymbol(
        char c,