Class Rule

base/src/main/java/net/time4j/CalendarUnit.java:627–789

Realisiert die Zeitarithmetik für eine kalendarische Zeiteinheit. @param generic type of calendrical context

     * @param   <T> generic type of calendrical context
     */
    static class Rule<T extends ChronoEntity<T>>
        implements UnitRule<T> {

        //~ Instanzvariablen ----------------------------------------------

        private final CalendarUnit unit;
        private final int policy;

        //~ Konstruktoren -------------------------------------------------

        /**
         * <p>Constructs a new rule for a calendar unit using the policy
         * {@code OverflowUnit.POLICY_PREVIOUS_VALID_DATE}. </p>
         *
         * @param   unit    calendar unit
         */
        Rule(CalendarUnit unit) {
            this(unit, OverflowUnit.POLICY_PREVIOUS_VALID_DATE);

        }

        /**
         * <p>Constructs a new rule for a calendar unit using the given
         * policy. </p>
         *
         * @param   unit    calendar unit as delegate
         * @param   policy  strategy for handling day overflow
         */
        Rule(
            CalendarUnit unit,
            int policy
        ) {
            super();

            this.unit = unit;
            this.policy = policy;

        }

        //~ Methoden ------------------------------------------------------

        @Override
        public T addTo(
            T context,
            long amount
        ) {

            PlainDate date = context.get(PlainDate.CALENDAR_DATE);
            date = PlainDate.doAdd(this.unit, date, amount, this.policy);
            return context.with(PlainDate.CALENDAR_DATE, date);

        }

        @Override
        public long between(T start, T end) {

            PlainDate d1 = start.get(PlainDate.CALENDAR_DATE);
            PlainDate d2 = end.get(PlainDate.CALENDAR_DATE);