Implemented more complete limit/expansion rules according to RFC5545

src/main/java/net/fortuna/ical4j/model/Recur.java

@@ -320,17 +320,17 @@ public Recur(final Frequency frequency, final int count) {
     private void initTransformers() {
         transformers = new HashMap<>();
         if (secondList != null) {
-            transformers.put(BYSECOND, new BySecondRule(secondList, Optional.ofNullable(weekStartDay)));
+            transformers.put(BYSECOND, new BySecondRule(secondList, frequency, Optional.ofNullable(weekStartDay)));
         } else {
             secondList = new NumberList(0, 59, false);
         }
         if (minuteList != null) {
-            transformers.put(BYMINUTE, new ByMinuteRule(minuteList, Optional.ofNullable(weekStartDay)));
+            transformers.put(BYMINUTE, new ByMinuteRule(minuteList, frequency, Optional.ofNullable(weekStartDay)));
         } else {
             minuteList = new NumberList(0, 59, false);
         }
         if (hourList != null) {
-            transformers.put(BYHOUR, new ByHourRule(hourList, Optional.ofNullable(weekStartDay)));
+            transformers.put(BYHOUR, new ByHourRule(hourList, frequency, Optional.ofNullable(weekStartDay)));
         } else {
             hourList = new NumberList(0, 23, false);
         }
@@ -350,7 +350,7 @@ private void initTransformers() {
             weekNoList = new NumberList(1, 53, true);
         }
         if (monthList != null) {
-            transformers.put(BYMONTH, new ByMonthRule(monthList, Optional.ofNullable(interval),
+            transformers.put(BYMONTH, new ByMonthRule(monthList, frequency,
                     Optional.ofNullable(weekStartDay)));
         } else {
             monthList = new NumberList(1, 12, false);

src/main/java/net/fortuna/ical4j/transform/recurrence/AbstractDateExpansionRule.java

@@ -0,0 +1,111 @@
+package net.fortuna.ical4j.transform.recurrence;
+
+import net.fortuna.ical4j.model.Date;
+import net.fortuna.ical4j.model.DateList;
+import net.fortuna.ical4j.model.WeekDay;
+import net.fortuna.ical4j.transform.Transformer;
+import net.fortuna.ical4j.util.Dates;
+
+import java.io.Serializable;
+import java.util.Calendar;
+import java.util.Optional;
+
+/**
+ * Subclasses provide implementations to expand (or limit) a list of dates based on rule requirements as
+ * specified in RFC5545.
+ *
+ * <pre>
+ *     3.3.10.  Recurrence Rule
+ *
+ *       ...
+ *
+ *       BYxxx rule parts modify the recurrence in some manner.  BYxxx rule
+ *       parts for a period of time that is the same or greater than the
+ *       frequency generally reduce or limit the number of occurrences of
+ *       the recurrence generated.  For example, "FREQ=DAILY;BYMONTH=1"
+ *       reduces the number of recurrence instances from all days (if
+ *       BYMONTH rule part is not present) to all days in January.  BYxxx
+ *       rule parts for a period of time less than the frequency generally
+ *       increase or expand the number of occurrences of the recurrence.
+ *       For example, "FREQ=YEARLY;BYMONTH=1,2" increases the number of
+ *       days within the yearly recurrence set from 1 (if BYMONTH rule part
+ *       is not present) to 2.
+ *
+ *       If multiple BYxxx rule parts are specified, then after evaluating
+ *       the specified FREQ and INTERVAL rule parts, the BYxxx rule parts
+ *       are applied to the current set of evaluated occurrences in the
+ *       following order: BYMONTH, BYWEEKNO, BYYEARDAY, BYMONTHDAY, BYDAY,
+ *       BYHOUR, BYMINUTE, BYSECOND and BYSETPOS; then COUNT and UNTIL are
+ *       evaluated.
+ *
+ *       The table below summarizes the dependency of BYxxx rule part
+ *       expand or limit behavior on the FREQ rule part value.
+ *
+ *       The term "N/A" means that the corresponding BYxxx rule part MUST
+ *       NOT be used with the corresponding FREQ value.
+ *
+ *       BYDAY has some special behavior depending on the FREQ value and
+ *       this is described in separate notes below the table.
+ *
+ *    +----------+--------+--------+-------+-------+------+-------+------+
+ *    |          |SECONDLY|MINUTELY|HOURLY |DAILY  |WEEKLY|MONTHLY|YEARLY|
+ *    +----------+--------+--------+-------+-------+------+-------+------+
+ *    |BYMONTH   |Limit   |Limit   |Limit  |Limit  |Limit |Limit  |Expand|
+ *    +----------+--------+--------+-------+-------+------+-------+------+
+ *    |BYWEEKNO  |N/A     |N/A     |N/A    |N/A    |N/A   |N/A    |Expand|
+ *    +----------+--------+--------+-------+-------+------+-------+------+
+ *    |BYYEARDAY |Limit   |Limit   |Limit  |N/A    |N/A   |N/A    |Expand|
+ *    +----------+--------+--------+-------+-------+------+-------+------+
+ *    |BYMONTHDAY|Limit   |Limit   |Limit  |Limit  |N/A   |Expand |Expand|
+ *    +----------+--------+--------+-------+-------+------+-------+------+
+ *    |BYDAY     |Limit   |Limit   |Limit  |Limit  |Expand|Note 1 |Note 2|
+ *    +----------+--------+--------+-------+-------+------+-------+------+
+ *    |BYHOUR    |Limit   |Limit   |Limit  |Expand |Expand|Expand |Expand|
+ *    +----------+--------+--------+-------+-------+------+-------+------+
+ *    |BYMINUTE  |Limit   |Limit   |Expand |Expand |Expand|Expand |Expand|
+ *    +----------+--------+--------+-------+-------+------+-------+------+
+ *    |BYSECOND  |Limit   |Expand  |Expand |Expand |Expand|Expand |Expand|
+ *    +----------+--------+--------+-------+-------+------+-------+------+
+ *    |BYSETPOS  |Limit   |Limit   |Limit  |Limit  |Limit |Limit  |Limit |
+ *    +----------+--------+--------+-------+-------+------+-------+------+
+ *
+ *       Note 1:  Limit if BYMONTHDAY is present; otherwise, special expand
+ *                for MONTHLY.
+ *
+ *       Note 2:  Limit if BYYEARDAY or BYMONTHDAY is present; otherwise,
+ *                special expand for WEEKLY if BYWEEKNO present; otherwise,
+ *                special expand for MONTHLY if BYMONTH present; otherwise,
+ *                special expand for YEARLY.
+ * </pre>
+ */
+public abstract class AbstractDateExpansionRule implements Transformer<DateList>, Serializable {
+
+    private final int calendarWeekStartDay;
+
+    public AbstractDateExpansionRule() {
+        // default week start is Monday per RFC5545
+        this(Optional.of(WeekDay.Day.MO));
+    }
+
+    public AbstractDateExpansionRule(Optional<WeekDay.Day> weekStartDay) {
+        this.calendarWeekStartDay = WeekDay.getCalendarDay(WeekDay.getWeekDay(weekStartDay.orElse(WeekDay.Day.MO)));
+    }
+
+    /**
+     * Construct a Calendar object and sets the time.
+     *
+     * @param date
+     * @param lenient
+     * @return
+     */
+    protected Calendar getCalendarInstance(final Date date, final boolean lenient) {
+        Calendar cal = Dates.getCalendarInstance(date);
+        // A week should have at least 4 days to be considered as such per RFC5545
+        cal.setMinimalDaysInFirstWeek(4);
+        cal.setFirstDayOfWeek(calendarWeekStartDay);
+        cal.setLenient(lenient);
+        cal.setTime(date);
+
+        return cal;
+    }
+}

src/main/java/net/fortuna/ical4j/transform/recurrence/ByDayRule.java

@@ -15,7 +15,7 @@
  * Applies BYDAY rules specified in this Recur instance to the specified date list. If no BYDAY rules are specified
  * the date list is returned unmodified.
  */
-public class ByDayRule extends AbstractRecurrenceRule {
+public class ByDayRule extends AbstractDateExpansionRule {
 
     public enum FilterType {
         Daily, Weekly, Monthly, Yearly;

src/main/java/net/fortuna/ical4j/transform/recurrence/ByHourRule.java

@@ -3,27 +3,35 @@
 import net.fortuna.ical4j.model.Date;
 import net.fortuna.ical4j.model.DateList;
 import net.fortuna.ical4j.model.NumberList;
+import net.fortuna.ical4j.model.Recur.Frequency;
 import net.fortuna.ical4j.model.WeekDay;
+import net.fortuna.ical4j.model.parameter.Value;
 import net.fortuna.ical4j.util.Dates;
 
-import java.util.Calendar;
-import java.util.Optional;
+import java.util.*;
+import java.util.function.Function;
+
+import static net.fortuna.ical4j.model.Recur.Frequency.*;
 
 /**
  * Applies BYHOUR rules specified in this Recur instance to the specified date list. If no BYHOUR rules are
  * specified the date list is returned unmodified.
  */
-public class ByHourRule extends AbstractRecurrenceRule {
+public class ByHourRule extends AbstractDateExpansionRule {
 
     private final NumberList hourList;
 
-    public ByHourRule(NumberList hourList) {
+    private final Frequency frequency;
+
+    public ByHourRule(NumberList hourList, Frequency frequency) {
         this.hourList = hourList;
+        this.frequency = frequency;
     }
 
-    public ByHourRule(NumberList hourList, Optional<WeekDay.Day> weekStartDay) {
+    public ByHourRule(NumberList hourList, Frequency frequency, Optional<WeekDay.Day> weekStartDay) {
         super(weekStartDay);
         this.hourList = hourList;
+        this.frequency = frequency;
     }
 
     @Override
@@ -33,12 +41,51 @@ public DateList transform(DateList dates) {
         }
         final DateList hourlyDates = Dates.getDateListInstance(dates);
         for (final Date date : dates) {
-            final Calendar cal = getCalendarInstance(date, true);
-            for (final Integer hour : hourList) {
-                cal.set(Calendar.HOUR_OF_DAY, hour);
-                hourlyDates.add(Dates.getInstance(cal.getTime(), hourlyDates.getType()));
+            if (EnumSet.of(DAILY, WEEKLY, MONTHLY, YEARLY).contains(frequency)) {
+                hourlyDates.addAll(new ExpansionFilter(hourlyDates.getType()).apply(date));
+            } else {
+                hourlyDates.addAll(new LimitFilter(hourlyDates.getType()).apply(date));
             }
         }
         return hourlyDates;
     }
+
+    private class LimitFilter implements Function<Date, List<Date>> {
+
+        private final Value type;
+
+        public LimitFilter(Value type) {
+            this.type = type;
+        }
+
+        @Override
+        public List<Date> apply(Date date) {
+            final Calendar cal = getCalendarInstance(date, true);
+            if (hourList.contains(cal.get(Calendar.HOUR_OF_DAY))) {
+                return Arrays.asList(date);
+            }
+            return Collections.emptyList();
+        }
+    }
+
+    private class ExpansionFilter implements Function<Date, List<Date>> {
+
+        private final Value type;
+
+        public ExpansionFilter(Value type) {
+            this.type = type;
+        }
+
+        @Override
+        public List<Date> apply(Date date) {
+            List<Date> retVal = new ArrayList<>();
+            final Calendar cal = getCalendarInstance(date, true);
+            // construct a list of possible months..
+            hourList.forEach(hour -> {
+                cal.set(Calendar.HOUR_OF_DAY, hour);
+                retVal.add(Dates.getInstance(cal.getTime(), type));
+            });
+            return retVal;
+        }
+    }
 }

src/main/java/net/fortuna/ical4j/transform/recurrence/ByMinuteRule.java

@@ -3,27 +3,35 @@
 import net.fortuna.ical4j.model.Date;
 import net.fortuna.ical4j.model.DateList;
 import net.fortuna.ical4j.model.NumberList;
+import net.fortuna.ical4j.model.Recur.Frequency;
 import net.fortuna.ical4j.model.WeekDay;
+import net.fortuna.ical4j.model.parameter.Value;
 import net.fortuna.ical4j.util.Dates;
 
-import java.util.Calendar;
-import java.util.Optional;
+import java.util.*;
+import java.util.function.Function;
+
+import static net.fortuna.ical4j.model.Recur.Frequency.*;
 
 /**
  * Applies BYMINUTE rules specified in this Recur instance to the specified date list. If no BYMINUTE rules are
  * specified the date list is returned unmodified.
  */
-public class ByMinuteRule extends AbstractRecurrenceRule {
+public class ByMinuteRule extends AbstractDateExpansionRule {
 
     private final NumberList minuteList;
 
-    public ByMinuteRule(NumberList minuteList) {
+    private final Frequency frequency;
+
+    public ByMinuteRule(NumberList minuteList, Frequency frequency) {
         this.minuteList = minuteList;
+        this.frequency = frequency;
     }
 
-    public ByMinuteRule(NumberList minuteList, Optional<WeekDay.Day> weekStartDay) {
+    public ByMinuteRule(NumberList minuteList, Frequency frequency, Optional<WeekDay.Day> weekStartDay) {
         super(weekStartDay);
         this.minuteList = minuteList;
+        this.frequency = frequency;
     }
 
     @Override
@@ -33,12 +41,51 @@ public DateList transform(DateList dates) {
         }
         final DateList minutelyDates = Dates.getDateListInstance(dates);
         for (final Date date : dates) {
-            final Calendar cal = getCalendarInstance(date, true);
-            for (final Integer minute : minuteList) {
-                cal.set(Calendar.MINUTE, minute);
-                minutelyDates.add(Dates.getInstance(cal.getTime(), minutelyDates.getType()));
+            if (EnumSet.of(HOURLY, DAILY, WEEKLY, MONTHLY, YEARLY).contains(frequency)) {
+                minutelyDates.addAll(new ExpansionFilter(minutelyDates.getType()).apply(date));
+            } else {
+                minutelyDates.addAll(new LimitFilter(minutelyDates.getType()).apply(date));
             }
         }
         return minutelyDates;
     }
+
+    private class LimitFilter implements Function<Date, List<Date>> {
+
+        private final Value type;
+
+        public LimitFilter(Value type) {
+            this.type = type;
+        }
+
+        @Override
+        public List<Date> apply(Date date) {
+            final Calendar cal = getCalendarInstance(date, true);
+            if (minuteList.contains(cal.get(Calendar.MINUTE))) {
+                return Arrays.asList(date);
+            }
+            return Collections.emptyList();
+        }
+    }
+
+    private class ExpansionFilter implements Function<Date, List<Date>> {
+
+        private final Value type;
+
+        public ExpansionFilter(Value type) {
+            this.type = type;
+        }
+
+        @Override
+        public List<Date> apply(Date date) {
+            List<Date> retVal = new ArrayList<>();
+            final Calendar cal = getCalendarInstance(date, true);
+            // construct a list of possible minutes..
+            minuteList.forEach(minute -> {
+                cal.set(Calendar.MINUTE, minute);
+                retVal.add(Dates.getInstance(cal.getTime(), type));
+            });
+            return retVal;
+        }
+    }
 }

src/main/java/net/fortuna/ical4j/transform/recurrence/ByMonthDayRule.java

@@ -13,7 +13,7 @@
  * Applies BYMONTHDAY rules specified in this Recur instance to the specified date list. If no BYMONTHDAY rules are
  * specified the date list is returned unmodified.
  */
-public class ByMonthDayRule extends AbstractRecurrenceRule {
+public class ByMonthDayRule extends AbstractDateExpansionRule {
 
     private transient Logger log = LoggerFactory.getLogger(ByMonthDayRule.class);