Evaluation: Make 'MaxIncrementCount' configurable.

Author: minichma

Ical.Net.Tests/RecurrenceTests.cs

@@ -17,6 +17,7 @@
 using Ical.Net.Serialization;
 using Ical.Net.Serialization.DataTypes;
 using NUnit.Framework;
+using NUnit.Framework.Constraints;
 
 namespace Ical.Net.Tests;
 
@@ -1232,8 +1233,8 @@ public void WeekNoOrderingShouldNotMatter()
         var rpe1 = new RecurrencePatternEvaluator(new RecurrencePattern("FREQ=YEARLY;WKST=MO;BYDAY=MO;BYWEEKNO=1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53"));
         var rpe2 = new RecurrencePatternEvaluator(new RecurrencePattern("FREQ=YEARLY;WKST=MO;BYDAY=MO;BYWEEKNO=53,51,49,47,45,43,41,39,37,35,33,31,29,27,25,23,21,19,17,15,13,11,9,7,5,3,1"));
 
-        var recurringPeriods1 = rpe1.Evaluate(new CalDateTime(start), start, end).ToList();
-        var recurringPeriods2 = rpe2.Evaluate(new CalDateTime(start), start, end).ToList();
+        var recurringPeriods1 = rpe1.Evaluate(new CalDateTime(start), start, end, default).ToList();
+        var recurringPeriods2 = rpe2.Evaluate(new CalDateTime(start), start, end, default).ToList();
 
         Assert.That(recurringPeriods2, Has.Count.EqualTo(recurringPeriods1.Count));
     }
@@ -2627,7 +2628,7 @@ public void BugByWeekNoNotWorking()
         var end = new CalDateTime(2019, 12, 31);
         var rpe = new RecurrencePatternEvaluator(new RecurrencePattern("FREQ=WEEKLY;BYDAY=MO;BYWEEKNO=2"));
 
-        var recurringPeriods = rpe.Evaluate(start, start, end).ToList();
+        var recurringPeriods = rpe.Evaluate(start, start, end, default).ToList();
 
         Assert.That(recurringPeriods, Has.Count.EqualTo(1));
         Assert.That(recurringPeriods.First().StartTime, Is.EqualTo(new CalDateTime(2019, 1, 7)));
@@ -2643,7 +2644,7 @@ public void BugByMonthWhileFreqIsWeekly()
         var end = new CalDateTime(2020, 12, 31);
         var rpe = new RecurrencePatternEvaluator(new RecurrencePattern("FREQ=WEEKLY;BYDAY=MO;BYMONTH=1"));
 
-        var recurringPeriods = rpe.Evaluate(start, start, end).OrderBy(x => x).ToList();
+        var recurringPeriods = rpe.Evaluate(start, start, end, default).OrderBy(x => x).ToList();
 
         Assert.That(recurringPeriods, Has.Count.EqualTo(4));
         Assert.Multiple(() =>
@@ -2686,7 +2687,7 @@ public void BugByMonthWhileFreqIsMonthly()
         var end = new CalDateTime(2020, 12, 31);
         var rpe = new RecurrencePatternEvaluator(new RecurrencePattern("FREQ=MONTHLY;BYDAY=MO;BYMONTH=1"));
 
-        var recurringPeriods = rpe.Evaluate(start, start, end).OrderBy(x => x).ToList();
+        var recurringPeriods = rpe.Evaluate(start, start, end, default).OrderBy(x => x).ToList();
 
         Assert.That(recurringPeriods, Has.Count.EqualTo(4));
         Assert.Multiple(() =>
@@ -2710,7 +2711,7 @@ public void Bug3119920()
         var serializer = new RecurrencePatternSerializer();
         var rp = (RecurrencePattern)serializer.Deserialize(sr)!;
         var rpe = new RecurrencePatternEvaluator(rp);
-        var recurringPeriods = rpe.Evaluate(start, start, rp.Until).ToList();
+        var recurringPeriods = rpe.Evaluate(start, start, rp.Until, default).ToList();
 
         var period = recurringPeriods.ElementAt(recurringPeriods.Count - 1);
 
@@ -2932,7 +2933,7 @@ public void RecurrencePattern1()
         var occurrences = evaluator.Evaluate(
             startDate,
             fromDate,
-            toDate)
+            toDate, default)
             .OrderBy(o => o.StartTime)
             .ToList();
         Assert.That(occurrences, Has.Count.EqualTo(4));
@@ -2964,7 +2965,7 @@ public void RecurrencePattern2()
         var occurrences = evaluator.Evaluate(
             startDate,
             fromDate,
-            toDate);
+            toDate, default);
         Assert.That(occurrences.Count, Is.Not.EqualTo(0));
     }
 
@@ -3071,7 +3072,7 @@ public void Test4()
         var periods = evaluator.Evaluate(
             evtStart,
             evtStart,
-            evtEnd)
+            evtEnd, default)
             .OrderBy(p => p.StartTime)
             .ToList();
         Assert.That(periods, Has.Count.EqualTo(10));
@@ -3905,7 +3906,7 @@ public void TestDtStartTimezone(string? tzId)
         var cal = Calendar.Load(icalText);
         var evt = cal.Events.First();
         var ev = new EventEvaluator(evt);
-        var occurrences = ev.Evaluate(evt.DtStart, evt.DtStart.ToTimeZone(tzId), evt.DtStart.AddMinutes(61).ToTimeZone(tzId));
+        var occurrences = ev.Evaluate(evt.DtStart, evt.DtStart.ToTimeZone(tzId), evt.DtStart.AddMinutes(61).ToTimeZone(tzId), default);
         var occurrencesStartTimes = occurrences.Select(x => x.StartTime).Take(2).ToList();
 
         var expectedStartTimes = new[]
@@ -3916,4 +3917,35 @@ public void TestDtStartTimezone(string? tzId)
 
         Assert.That(expectedStartTimes.SequenceEqual(occurrencesStartTimes), Is.True);
     }
+
+    [Test]
+    [TestCase(null, false)]
+    [TestCase(0, true)]
+    [TestCase(1000, true)]
+    [TestCase(1440, false)]
+    public void TestMaxIncrementCount(int? limit, bool expectException)
+    {
+        var ical = """
+            BEGIN:VCALENDAR
+            BEGIN:VEVENT
+            DTSTART:20250305T000000
+            RRULE:FREQ=MINUTELY;BYHOUR=0;COUNT=100
+            END:VEVENT
+            END:VCALENDAR
+            """;
+
+        var cal = Calendar.Load(ical);
+
+        var options = new EvaluationOptions
+        {
+            MaxIncrementCount = limit,
+        };
+
+        IResolveConstraint constraint =
+            expectException
+            ? Throws.Exception.TypeOf<MaxIncrementsExceededEvaluationException>()
+            : Throws.Nothing;
+
+        Assert.That(() => cal.GetOccurrences(options: options).ToList(), constraint);
+    }
 }

Ical.Net/Calendar.cs

@@ -11,6 +11,7 @@
 using System.Text;
 using Ical.Net.CalendarComponents;
 using Ical.Net.DataTypes;
+using Ical.Net.Evaluation;
 using Ical.Net.Proxies;
 using Ical.Net.Serialization;
 using Ical.Net.Utility;
@@ -190,16 +191,16 @@ public VTimeZone AddTimeZone(VTimeZone tz)
     /// <param name="startTime">The beginning date/time of the range.</param>
     /// <param name="endTime">The end date/time of the range.</param>
     /// <returns>A list of occurrences that fall between the date/time arguments provided.</returns>
-    public virtual IEnumerable<Occurrence> GetOccurrences(CalDateTime startTime = null, CalDateTime endTime = null)
-        => GetOccurrences<IRecurringComponent>(startTime, endTime);
+    public virtual IEnumerable<Occurrence> GetOccurrences(CalDateTime startTime = null, CalDateTime endTime = null, EvaluationOptions options = default)
+        => GetOccurrences<IRecurringComponent>(startTime, endTime, options);
 
     /// <inheritdoc cref="GetOccurrences(CalDateTime, CalDateTime)"/>
-    public virtual IEnumerable<Occurrence> GetOccurrences(DateTime? startTime, DateTime? endTime)
-        => GetOccurrences<IRecurringComponent>(startTime?.AsCalDateTime(), endTime?.AsCalDateTime());
+    public virtual IEnumerable<Occurrence> GetOccurrences(DateTime? startTime, DateTime? endTime, EvaluationOptions options = default)
+        => GetOccurrences<IRecurringComponent>(startTime?.AsCalDateTime(), endTime?.AsCalDateTime(), options);
 
     /// <inheritdoc cref="GetOccurrences(CalDateTime, CalDateTime)"/>
-    public virtual IEnumerable<Occurrence> GetOccurrences<T>(DateTime? startTime, DateTime? endTime) where T : IRecurringComponent
-        => GetOccurrences<T>(startTime?.AsCalDateTime(), endTime?.AsCalDateTime());
+    public virtual IEnumerable<Occurrence> GetOccurrences<T>(DateTime? startTime, DateTime? endTime, EvaluationOptions options = default) where T : IRecurringComponent
+        => GetOccurrences<T>(startTime?.AsCalDateTime(), endTime?.AsCalDateTime(), options);
 
     /// <summary>
     /// Returns all occurrences of components of type T that start within the date range provided.
@@ -208,7 +209,7 @@ public virtual IEnumerable<Occurrence> GetOccurrences<T>(DateTime? startTime, Da
     /// </summary>
     /// <param name="startTime">The starting date range</param>
     /// <param name="endTime">The ending date range</param>
-    public virtual IEnumerable<Occurrence> GetOccurrences<T>(CalDateTime startTime = null, CalDateTime endTime = null) where T : IRecurringComponent
+    public virtual IEnumerable<Occurrence> GetOccurrences<T>(CalDateTime startTime = null, CalDateTime endTime = null, EvaluationOptions options = default) where T : IRecurringComponent
     {
         // These are the UID/RECURRENCE-ID combinations that replace other occurrences.
         var recurrenceIdsAndUids = this.Children.OfType<IRecurrable>()
@@ -219,7 +220,7 @@ public virtual IEnumerable<Occurrence> GetOccurrences<T>(CalDateTime startTime =
 
         var occurrences = RecurringItems
             .OfType<T>()
-            .Select(recurrable => recurrable.GetOccurrences(startTime, endTime))
+            .Select(recurrable => recurrable.GetOccurrences(startTime, endTime, options))
 
             // Enumerate the list of occurrences (not the occurrences themselves) now to ensure
             // the initialization code is run, including validation and error handling.

Ical.Net/CalendarCollection.cs

@@ -10,8 +10,10 @@
 using System.Text;
 using Ical.Net.CalendarComponents;
 using Ical.Net.DataTypes;
+using Ical.Net.Evaluation;
 using Ical.Net.Serialization;
 using Ical.Net.Utility;
+using static NodaTime.TimeZones.ZoneEqualityComparer;
 
 namespace Ical.Net;
 
@@ -55,17 +57,17 @@ private IEnumerable<Occurrence> GetOccurrences(Func<Calendar, IEnumerable<Occurr
         // being ordered to avoid full enumeration.
         .OrderedMergeMany();
 
-    public IEnumerable<Occurrence> GetOccurrences(CalDateTime startTime = null, CalDateTime endTime = null)
-        => GetOccurrences(iCal => iCal.GetOccurrences(startTime, endTime));
+    public IEnumerable<Occurrence> GetOccurrences(CalDateTime startTime = null, CalDateTime endTime = null, EvaluationOptions options = default)
+        => GetOccurrences(iCal => iCal.GetOccurrences(startTime, endTime, options));
 
-    public IEnumerable<Occurrence> GetOccurrences(DateTime? startTime, DateTime? endTime)
-        => GetOccurrences(iCal => iCal.GetOccurrences(startTime, endTime));
+    public IEnumerable<Occurrence> GetOccurrences(DateTime? startTime, DateTime? endTime, EvaluationOptions options = default)
+        => GetOccurrences(iCal => iCal.GetOccurrences(startTime, endTime, options));
 
-    public IEnumerable<Occurrence> GetOccurrences<T>(CalDateTime startTime = null, CalDateTime endTime = null) where T : IRecurringComponent
-        => GetOccurrences(iCal => iCal.GetOccurrences<T>(startTime, endTime));
+    public IEnumerable<Occurrence> GetOccurrences<T>(CalDateTime startTime = null, CalDateTime endTime = null, EvaluationOptions options = default) where T : IRecurringComponent
+        => GetOccurrences(iCal => iCal.GetOccurrences<T>(startTime, endTime, options));
 
-    public IEnumerable<Occurrence> GetOccurrences<T>(DateTime? startTime, DateTime? endTime) where T : IRecurringComponent
-        => GetOccurrences(iCal => iCal.GetOccurrences<T>(startTime, endTime));
+    public IEnumerable<Occurrence> GetOccurrences<T>(DateTime? startTime, DateTime? endTime, EvaluationOptions options = default) where T : IRecurringComponent
+        => GetOccurrences(iCal => iCal.GetOccurrences<T>(startTime, endTime, options));
 
     private FreeBusy CombineFreeBusy(FreeBusy main, FreeBusy current)
     {

Ical.Net/CalendarComponents/Alarm.cs

@@ -7,6 +7,7 @@
 using System;
 using System.Collections.Generic;
 using Ical.Net.DataTypes;
+using Ical.Net.Evaluation;
 
 namespace Ical.Net.CalendarComponents;
 
@@ -73,7 +74,7 @@ public Alarm()
     /// Gets a list of alarm occurrences for the given recurring component, <paramref name="rc"/>
     /// that occur between <paramref name="fromDate"/> and <paramref name="toDate"/>.
     /// </summary>
-    public virtual IList<AlarmOccurrence> GetOccurrences(IRecurringComponent rc, CalDateTime? fromDate, CalDateTime? toDate)
+    public virtual IList<AlarmOccurrence> GetOccurrences(IRecurringComponent rc, CalDateTime? fromDate, CalDateTime? toDate, EvaluationOptions options)
     {
         if (Trigger == null)
         {
@@ -94,7 +95,7 @@ public virtual IList<AlarmOccurrence> GetOccurrences(IRecurringComponent rc, Cal
             }
 
             Duration? duration = null;
-            foreach (var o in rc.GetOccurrences(fromDate, toDate))
+            foreach (var o in rc.GetOccurrences(fromDate, toDate, options))
             {
                 var dt = o.Period.StartTime;
                 if (string.Equals(Trigger.Related, TriggerRelation.End, TriggerRelation.Comparison))
@@ -143,7 +144,7 @@ public virtual IList<AlarmOccurrence> GetOccurrences(IRecurringComponent rc, Cal
     /// <param name="start">The earliest date/time to poll trigered alarms for.</param>
     /// <param name="end"></param>
     /// <returns>A list of <see cref="AlarmOccurrence"/> objects, each containing a triggered alarm.</returns>
-    public virtual IList<AlarmOccurrence> Poll(CalDateTime start, CalDateTime end)
+    public virtual IList<AlarmOccurrence> Poll(CalDateTime start, CalDateTime end, EvaluationOptions options = default)
     {
         var results = new List<AlarmOccurrence>();
 
@@ -154,7 +155,7 @@ public virtual IList<AlarmOccurrence> Poll(CalDateTime start, CalDateTime end)
             return results;
         }
 
-        results.AddRange(GetOccurrences(rc, start, end));
+        results.AddRange(GetOccurrences(rc, start, end, options));
         return results;
     }
 

Ical.Net/CalendarComponents/FreeBusy.cs

@@ -7,20 +7,21 @@
 using System.Collections.Generic;
 using System.Linq;
 using Ical.Net.DataTypes;
+using Ical.Net.Evaluation;
 using Ical.Net.Utility;
 
 namespace Ical.Net.CalendarComponents;
 
 public class FreeBusy : UniqueComponent, IMergeable
 {
-    public static FreeBusy Create(ICalendarObject obj, FreeBusy freeBusyRequest)
+    public static FreeBusy Create(ICalendarObject obj, FreeBusy freeBusyRequest, EvaluationOptions options = default)
     {
         if (!(obj is IGetOccurrencesTyped))
         {
             return null;
         }
         var getOccurrences = (IGetOccurrencesTyped) obj;
-        var occurrences = getOccurrences.GetOccurrences<CalendarEvent>(freeBusyRequest.Start, freeBusyRequest.End);
+        var occurrences = getOccurrences.GetOccurrences<CalendarEvent>(freeBusyRequest.Start, freeBusyRequest.End, options);
         var contacts = new List<string>();
         var isFilteredByAttendees = false;
 
@@ -196,4 +197,4 @@ public virtual void MergeWith(IMergeable obj)
 
         Entries.AddRange(fb.Entries.Where(entry => !Entries.Contains(entry)));
     }
-}
+}

Ical.Net/CalendarComponents/RecurringComponent.cs

@@ -185,11 +185,11 @@ protected override void OnDeserializing(StreamingContext context)
         Initialize();
     }
 
-    public virtual IEnumerable<Occurrence> GetOccurrences(CalDateTime startTime = null, CalDateTime endTime = null)
-        => RecurrenceUtil.GetOccurrences(this, startTime, endTime);
+    public virtual IEnumerable<Occurrence> GetOccurrences(CalDateTime startTime = null, CalDateTime endTime = null, EvaluationOptions options = default)
+        => RecurrenceUtil.GetOccurrences(this, startTime, endTime, options);
 
-    public virtual IEnumerable<Occurrence> GetOccurrences(DateTime? startTime, DateTime? endTime)
-        => RecurrenceUtil.GetOccurrences(this, startTime?.AsCalDateTime(), endTime?.AsCalDateTime());
+    public virtual IEnumerable<Occurrence> GetOccurrences(DateTime? startTime, DateTime? endTime, EvaluationOptions options = default)
+        => RecurrenceUtil.GetOccurrences(this, startTime?.AsCalDateTime(), endTime?.AsCalDateTime(), options);
 
     public virtual IList<AlarmOccurrence> PollAlarms() => PollAlarms(null, null);
 

Ical.Net/CalendarComponents/Todo.cs

@@ -146,7 +146,7 @@ public virtual bool IsCompleted(CalDateTime currDt)
             }
 
             // Evaluate to the previous occurrence.
-            var periods = _mEvaluator.EvaluateToPreviousOccurrence(Completed, currDt);
+            var periods = _mEvaluator.EvaluateToPreviousOccurrence(Completed, currDt, options: default);
 
             return periods.All(p => !p.StartTime.GreaterThan(Completed) || !currDt.GreaterThanOrEqual(p.StartTime));
         }

Ical.Net/Evaluation/EvaluationOptions.cs

@@ -0,0 +1,20 @@
+//
+// Copyright ical.net project maintainers and contributors.
+// Licensed under the MIT license.
+//
+
+namespace Ical.Net.Evaluation;
+public class EvaluationOptions
+{
+    /// <summary>
+    /// The maximum number of increments to evaluate without finding a recurrence before
+    /// evaluation is stopped exceptionally. If null, the evaluation will continue indefinitely.
+    /// </summary>
+    /// <remarks>
+    /// This option only applies to the evaluation of RecurrencePatterns.
+    ///
+    /// If the specified number of increments is exceeded without finding a recurrence, an
+    /// exception of type <see cref="Ical.Net.Evaluation.MaxIncrementsExceededEvaluationException"/> will be thrown.
+    /// </remarks>
+    public int? MaxIncrementCount { get; set; }
+}

Ical.Net/Evaluation/Evaluator.cs

@@ -56,5 +56,5 @@ protected void IncrementDate(ref CalDateTime dt, RecurrencePattern pattern, int
 
     public System.Globalization.Calendar Calendar { get; private set; }
 
-    public abstract IEnumerable<Period> Evaluate(CalDateTime referenceDate, CalDateTime? periodStart, CalDateTime? periodEnd);
+    public abstract IEnumerable<Period> Evaluate(CalDateTime referenceDate, CalDateTime? periodStart, CalDateTime? periodEnd, EvaluationOptions options);
 }

Ical.Net/Evaluation/EventEvaluator.cs

@@ -40,12 +40,12 @@ public EventEvaluator(CalendarEvent evt) : base(evt) { }
     /// <param name="referenceTime"></param>
     /// <param name="periodStart">The beginning date of the range to evaluate.</param>
     /// <param name="periodEnd">The end date of the range to evaluate.</param>
-    /// <param name="includeReferenceDateInResults"></param>
+    /// <param name="options"></param>
     /// <returns></returns>
-    public override IEnumerable<Period> Evaluate(CalDateTime referenceTime, CalDateTime? periodStart, CalDateTime? periodEnd)
+    public override IEnumerable<Period> Evaluate(CalDateTime referenceTime, CalDateTime? periodStart, CalDateTime? periodEnd, EvaluationOptions options)
     {
         // Evaluate recurrences normally
-        var periods = base.Evaluate(referenceTime, periodStart, periodEnd)
+        var periods = base.Evaluate(referenceTime, periodStart, periodEnd, options)
             .Select(WithEndTime);
 
         return periods;