Added skip behaviour for BYMONTH rules

ical4j · Jul 6, 2021 · 73c8bad · 73c8bad
1 parent 19493b4
commit 73c8bad
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Showing 3 changed files with 61 additions and 10 deletions.
diff --git a/src/main/java/net/fortuna/ical4j/model/Recur.java b/src/main/java/net/fortuna/ical4j/model/Recur.java
@@ -397,7 +397,7 @@ private void initTransformers() {
         }
         if (monthList != null) {
             transformers.put(BYMONTH, new ByMonthRule(monthList, frequency,
-                    Optional.ofNullable(weekStartDay)));
+                    Optional.ofNullable(weekStartDay), skip));
         } else {
             monthList = new MonthList(chronology.range(ChronoField.MONTH_OF_YEAR));
         }

diff --git a/src/main/java/net/fortuna/ical4j/transform/recurrence/ByMonthRule.java b/src/main/java/net/fortuna/ical4j/transform/recurrence/ByMonthRule.java
@@ -19,13 +19,24 @@ public class ByMonthRule extends AbstractDateExpansionRule {
 
     private final MonthList monthList;
 
+    private final Recur.Skip skip;
+
     public ByMonthRule(MonthList monthList, Frequency frequency) {
-        this(monthList, frequency, Optional.empty());
+        this(monthList, frequency, Recur.Skip.OMIT);
+    }
+
+    public ByMonthRule(MonthList monthList, Frequency frequency, Recur.Skip skip) {
+        this(monthList, frequency, Optional.empty(), skip);
     }
 
     public ByMonthRule(MonthList monthList, Frequency frequency, Optional<WeekDay.Day> weekStartDay) {
+        this(monthList, frequency, weekStartDay, Recur.Skip.OMIT);
+    }
+
+    public ByMonthRule(MonthList monthList, Frequency frequency, Optional<WeekDay.Day> weekStartDay, Recur.Skip skip) {
         super(frequency, weekStartDay);
         this.monthList = monthList;
+        this.skip = skip;
     }
 
     @Override
@@ -73,12 +84,22 @@ public List<Date> apply(Date date) {
             List<Date> retVal = new ArrayList<>();
             final Calendar cal = getCalendarInstance(date, true);
             // construct a list of possible months..
-            monthList.forEach(month -> {
-                // Java months are zero-based..
+            for (Month month : monthList) {
+                if (month.isLeapMonth()) {
+                    if (skip == Recur.Skip.BACKWARD) {
+                        cal.roll(Calendar.MONTH, (month.getMonthOfYear() - 1) - cal.get(Calendar.MONTH));
+                    } else if (skip == Recur.Skip.FORWARD) {
+                        cal.roll(Calendar.MONTH, month.getMonthOfYear() - cal.get(Calendar.MONTH));
+                    } else {
+                        continue;
+                    }
+                } else {
+                    // Java months are zero-based..
 //                cal.set(Calendar.MONTH, month - 1);
-                cal.roll(Calendar.MONTH, (month.getMonthOfYear() - 1) - cal.get(Calendar.MONTH));
+                    cal.roll(Calendar.MONTH, (month.getMonthOfYear() - 1) - cal.get(Calendar.MONTH));
+                }
                 retVal.add(Dates.getInstance(getTime(date, cal), type));
-            });
+            }
             return retVal;
         }
     }

diff --git a/src/test/groovy/net/fortuna/ical4j/transform/recurrence/ByMonthRuleTest.groovy b/src/test/groovy/net/fortuna/ical4j/transform/recurrence/ByMonthRuleTest.groovy
@@ -1,9 +1,6 @@
 package net.fortuna.ical4j.transform.recurrence
 
-import net.fortuna.ical4j.model.Date
-import net.fortuna.ical4j.model.DateList
-import net.fortuna.ical4j.model.DateTime
-import net.fortuna.ical4j.model.MonthList
+import net.fortuna.ical4j.model.*
 import net.fortuna.ical4j.model.parameter.Value
 import spock.lang.Specification
 
@@ -29,5 +26,38 @@ class ByMonthRuleTest extends Specification {
         '2'         | YEARLY | [new DateTime("20200229T000000")] | Value.DATE_TIME | [new DateTime("20200229T000000")]
         '10,12'         | YEARLY | [new Date("20181010")]            | Value.DATE      | [new Date("20181010"), new Date("20181210")]
         '10,12'         | DAILY | [new Date("20181010"), new Date("20181110"), new Date("20181210")]            | Value.DATE      | [new Date("20181010"), new Date("20181210")]
+        '5L'        | YEARLY    | [new Date('20150103')]            | Value.DATE                        | []
+    }
+
+    def 'verify transformations by month with skip backward'() {
+        given: 'a bymonth rule'
+        ByMonthRule rule = [new MonthList(byMonthPart), frequency, Recur.Skip.BACKWARD]
+
+        and: 'a list of dates'
+        DateList dateList = [valueType]
+        dateList.addAll(dates)
+
+        expect: 'the rule transforms the dates correctly'
+        rule.transform(dateList) == expectedResult
+
+        where:
+        byMonthPart | frequency | dates                             | valueType                         | expectedResult
+        '5L'        | YEARLY    | [new Date('20150103')]            | Value.DATE                        | [new Date('20150503')]
+    }
+
+    def 'verify transformations by month with skip forward'() {
+        given: 'a bymonth rule'
+        ByMonthRule rule = [new MonthList(byMonthPart), frequency, Recur.Skip.FORWARD]
+
+        and: 'a list of dates'
+        DateList dateList = [valueType]
+        dateList.addAll(dates)
+
+        expect: 'the rule transforms the dates correctly'
+        rule.transform(dateList) == expectedResult
+
+        where:
+        byMonthPart | frequency | dates                             | valueType     | expectedResult
+        '5L'        | YEARLY    | [new Date('20150103')]            | Value.DATE    | [new Date('20150603')]
     }
 }