Enable NRT for Serialization namespace

Ical.Net/DataTypes/RequestStatus.cs

@@ -61,7 +61,7 @@ public override void CopyFrom(ICopyable obj)
         ExtraData = rs.ExtraData;
     }
 
-    public override string ToString()
+    public override string? ToString()
     {
         var serializer = new RequestStatusSerializer();
         return serializer.SerializeToString(this);

Ical.Net/DataTypes/StatusCode.cs

@@ -68,7 +68,7 @@
         statusCode.Parts.CopyTo(Parts, 0);
     }
 
-    public override string ToString() => new StatusCodeSerializer().SerializeToString(this);
+    public override string? ToString() => new StatusCodeSerializer().SerializeToString(this);
 
     protected bool Equals(StatusCode other) => Parts.SequenceEqual(other.Parts);
 

Ical.Net/Serialization/CalendarComponentFactory.cs

@@ -3,6 +3,7 @@
 // Licensed under the MIT license.
 //
 
+#nullable enable
 using Ical.Net.CalendarComponents;
 
 namespace Ical.Net.Serialization;
@@ -48,4 +49,4 @@ public virtual ICalendarComponent Build(string objectName)
         c.Name = name;
         return c;
     }
-}
+}

Ical.Net/Serialization/CalendarSerializer.cs

@@ -3,6 +3,7 @@
 // Licensed under the MIT license.
 //
 
+#nullable enable
 using System;
 using System.Collections.Generic;
 using System.IO;
@@ -11,7 +12,7 @@
 
 public class CalendarSerializer : ComponentSerializer
 {
-    private readonly Calendar _calendar;
+    private readonly Calendar? _calendar;
 
     public CalendarSerializer()
         : this(new SerializationContext()) { }
@@ -23,16 +24,16 @@
 
     public CalendarSerializer(SerializationContext ctx) : base(ctx) { }
 
-    public virtual string SerializeToString() => SerializeToString(_calendar);
+    public virtual string? SerializeToString() => SerializeToString(_calendar);
 
     protected override IComparer<ICalendarProperty> PropertySorter => new CalendarPropertySorter();
 
 
-    public override object Deserialize(TextReader tr) => null;
+    public override object? Deserialize(TextReader tr) => null;
 
     private class CalendarPropertySorter : IComparer<ICalendarProperty>
     {
-        public int Compare(ICalendarProperty x, ICalendarProperty y)
+        public int Compare(ICalendarProperty? x, ICalendarProperty? y)
         {
             if (x == y)
             {

Ical.Net/Serialization/ComponentSerializer.cs

@@ -3,6 +3,7 @@
 // Licensed under the MIT license.
 //
 
+#nullable enable
 using System;
 using System.Collections.Generic;
 using System.IO;
@@ -23,9 +24,9 @@
 
     public override Type TargetType => typeof(CalendarComponent);
 
-    public override string SerializeToString(object obj)
+    public override string? SerializeToString(object? obj)
     {
-        if (!(obj is ICalendarComponent c))
+        if (obj is not ICalendarComponent c || SerializationContext == null)
         {
             return null;
         }
@@ -44,27 +45,29 @@
         foreach (var p in properties)
         {
             // Get a serializer for each property.
-            var serializer = sf.Build(p.GetType(), SerializationContext) as IStringSerializer;
-            sb.Append(serializer.SerializeToString(p));
+            var serializer = sf?.Build(p.GetType(), SerializationContext) as IStringSerializer;
+            var val = serializer?.SerializeToString(p);
+            if (val != null) sb.Append(val);
         }
 
         // Serialize child objects
         foreach (var child in c.Children)
         {
             // Get a serializer for each child object.
-            var serializer = sf.Build(child.GetType(), SerializationContext) as IStringSerializer;
-            sb.Append(serializer.SerializeToString(child));
+            var serializer = sf?.Build(child.GetType(), SerializationContext) as IStringSerializer;
+            var val = serializer?.SerializeToString(child);
+            if (val != null) sb.Append(val);
         }
 
         sb.FoldLines($"END:{upperName}");
         return sb.ToString();
     }
 
-    public override object Deserialize(TextReader tr) => null;
+    public override object? Deserialize(TextReader tr) => null;
 
     public class PropertyAlphabetizer : IComparer<ICalendarProperty>
     {
-        public int Compare(ICalendarProperty x, ICalendarProperty y)
+        public int Compare(ICalendarProperty? x, ICalendarProperty? y)
         {
             if (x == y)
             {

Ical.Net/Serialization/DataMapSerializer.cs

@@ -3,6 +3,7 @@
 // Licensed under the MIT license.
 //
 
+#nullable enable
 using System;
 using System.IO;
 using Ical.Net.Serialization.DataTypes;
@@ -15,19 +16,19 @@
 
     public DataMapSerializer(SerializationContext ctx) : base(ctx) { }
 
-    protected IStringSerializer GetMappedSerializer()
+    protected IStringSerializer? GetMappedSerializer()
     {
         var sf = GetService<ISerializerFactory>();
         var mapper = GetService<DataTypeMapper>();
-        if (sf == null || mapper == null)
+        if (sf == null || mapper == null || SerializationContext == null)
         {
             return null;
         }
 
         var obj = SerializationContext.Peek();
 
         // Get the data type for this object
-        var type = mapper.GetPropertyMapping(obj);
+        var type = obj != null ? mapper.GetPropertyMapping(obj) : null;
 
         return type == null
             ? new StringSerializer(SerializationContext)
@@ -38,18 +39,18 @@
     {
         get
         {
-            ISerializer serializer = GetMappedSerializer();
-            return serializer?.TargetType;
+            ISerializer serializer = GetMappedSerializer() ?? throw new InvalidOperationException("Cannot detect the mapped serializer");
+            return serializer.TargetType;
         }
     }
 
-    public override string SerializeToString(object obj)
+    public override string? SerializeToString(object? obj)
     {
         var serializer = GetMappedSerializer();
         return serializer?.SerializeToString(obj);
     }
 
-    public override object Deserialize(TextReader tr)
+    public override object? Deserialize(TextReader tr)
     {
         var serializer = GetMappedSerializer();
         if (serializer == null)
@@ -67,4 +68,4 @@
         // as try/catch is much slower than other means.
         return returnValue ?? value;
     }
-}
+}

Ical.Net/Serialization/DataTypeMapper.cs

@@ -3,6 +3,7 @@
 // Licensed under the MIT license.
 //
 
+#nullable enable
 using System;
 using System.Collections.Generic;
 using Ical.Net.CalendarComponents;
@@ -16,8 +17,8 @@
 {
     private class PropertyMapping
     {
-        public Type ObjectType { get; set; }
-        public TypeResolverDelegate Resolver { get; set; }
+        public Type? ObjectType { get; set; }
+        public TypeResolverDelegate? Resolver { get; set; }
         public bool AllowsMultipleValuesPerProperty { get; set; }
     }
 
@@ -66,25 +67,21 @@
 
     protected Type ResolveStatusProperty(object context)
     {
-        if (!(context is ICalendarObject obj))
+        if (context is not ICalendarObject obj)
         {
-            return null;
+            return typeof(object); // Return a default type to match the delegate signature  
         }
 
-        switch (obj.Parent)
+        return obj.Parent switch
         {
-            case CalendarEvent _:
-                return typeof(EventStatus);
-            case Todo _:
-                return typeof(TodoStatus);
-            case Journal _:
-                return typeof(JournalStatus);
-        }
-
-        return null;
+            CalendarEvent _ => typeof(EventStatus),
+            Todo _ => typeof(TodoStatus),
+            Journal _ => typeof(JournalStatus),
+            _ => typeof(object) // Return a default type to match the delegate signature  
+        };
     }
 
-    public void AddPropertyMapping(string name, Type objectType, bool allowsMultipleValues)
+    public void AddPropertyMapping(string? name, Type? objectType, bool allowsMultipleValues)
     {
         if (name == null || objectType == null)
         {
@@ -100,7 +97,7 @@
         _propertyMap[name] = m;
     }
 
-    public void AddPropertyMapping(string name, TypeResolverDelegate resolver, bool allowsMultipleValues)
+    public void AddPropertyMapping(string? name, TypeResolverDelegate? resolver, bool allowsMultipleValues)
     {
         if (name == null || resolver == null)
         {
@@ -116,7 +113,7 @@
         _propertyMap[name] = m;
     }
 
-    public void RemovePropertyMapping(string name)
+    public void RemovePropertyMapping(string? name)
     {
         if (name != null && _propertyMap.ContainsKey(name))
         {
@@ -132,7 +129,7 @@
                && m.AllowsMultipleValuesPerProperty;
     }
 
-    public virtual Type GetPropertyMapping(object obj)
+    public virtual Type? GetPropertyMapping(object obj)
     {
         var p = obj as ICalendarProperty;
         if (p?.Name == null)

Ical.Net/Serialization/DataTypeSerializerFactory.cs

@@ -3,94 +3,53 @@
 // Licensed under the MIT license.
 //
 
+#nullable enable
 using System;
+using System.Collections.Generic;
+using System.Linq;
 using Ical.Net.DataTypes;
 using Ical.Net.Serialization.DataTypes;
 
 namespace Ical.Net.Serialization;
 
 public class DataTypeSerializerFactory : ISerializerFactory
 {
+    private static readonly Dictionary<Type, Func<SerializationContext, ISerializer>> _serializerMap =
+        new()
+        {
+            { typeof(Attachment), ctx => new AttachmentSerializer(ctx) },
+            { typeof(Attendee), ctx => new AttendeeSerializer(ctx) },
+            { typeof(CalDateTime), ctx => new DateTimeSerializer(ctx) },
+            { typeof(FreeBusyEntry), ctx => new FreeBusyEntrySerializer(ctx) },
+            { typeof(GeographicLocation), ctx => new GeographicLocationSerializer(ctx) },
+            { typeof(Organizer), ctx => new OrganizerSerializer(ctx) },
+            { typeof(Period), ctx => new PeriodSerializer(ctx) },
+            { typeof(PeriodList), ctx => new PeriodListSerializer(ctx) },
+            { typeof(RecurrencePattern), ctx => new RecurrencePatternSerializer(ctx) },
+            { typeof(RequestStatus), ctx => new RequestStatusSerializer(ctx) },
+            { typeof(StatusCode), ctx => new StatusCodeSerializer(ctx) },
+            { typeof(Trigger), ctx => new TriggerSerializer(ctx) },
+            { typeof(UtcOffset), ctx => new UtcOffsetSerializer(ctx) },
+            { typeof(WeekDay), ctx => new WeekDaySerializer(ctx) }
+        };
+
     /// <summary>
     /// Returns a serializer that can be used to serialize and object
     /// of type <paramref name="objectType"/>.
-    /// <note>
-    ///     TODO: Add support for caching.
-    /// </note>
     /// </summary>
     /// <param name="objectType">The type of object to be serialized.</param>
     /// <param name="ctx">The serialization context.</param>
-    public virtual ISerializer Build(Type objectType, SerializationContext ctx)
+    public virtual ISerializer? Build(Type? objectType, SerializationContext ctx)
     {
-        if (objectType != null)
-        {
-            ISerializer s;
+        if (objectType == null) return null;
 
-            if (typeof(Attachment).IsAssignableFrom(objectType))
-            {
-                s = new AttachmentSerializer(ctx);
-            }
-            else if (typeof(Attendee).IsAssignableFrom(objectType))
-            {
-                s = new AttendeeSerializer(ctx);
-            }
-            else if (typeof(CalDateTime).IsAssignableFrom(objectType))
-            {
-                s = new DateTimeSerializer(ctx);
-            }
-            else if (typeof(FreeBusyEntry).IsAssignableFrom(objectType))
-            {
-                s = new FreeBusyEntrySerializer(ctx);
-            }
-            else if (typeof(GeographicLocation).IsAssignableFrom(objectType))
-            {
-                s = new GeographicLocationSerializer(ctx);
-            }
-            else if (typeof(Organizer).IsAssignableFrom(objectType))
-            {
-                s = new OrganizerSerializer(ctx);
-            }
-            else if (typeof(Period).IsAssignableFrom(objectType))
-            {
-                s = new PeriodSerializer(ctx);
-            }
-            else if (typeof(PeriodList).IsAssignableFrom(objectType))
-            {
-                s = new PeriodListSerializer(ctx);
-            }
-            else if (typeof(RecurrencePattern).IsAssignableFrom(objectType))
-            {
-                s = new RecurrencePatternSerializer(ctx);
-            }
-            else if (typeof(RequestStatus).IsAssignableFrom(objectType))
-            {
-                s = new RequestStatusSerializer(ctx);
-            }
-            else if (typeof(StatusCode).IsAssignableFrom(objectType))
-            {
-                s = new StatusCodeSerializer(ctx);
-            }
-            else if (typeof(Trigger).IsAssignableFrom(objectType))
-            {
-                s = new TriggerSerializer(ctx);
-            }
-            else if (typeof(UtcOffset).IsAssignableFrom(objectType))
-            {
-                s = new UtcOffsetSerializer(ctx);
-            }
-            else if (typeof(WeekDay).IsAssignableFrom(objectType))
-            {
-                s = new WeekDaySerializer(ctx);
-            }
-            // Default to a string serializer, which simply calls
-            // ToString() on the value to serialize it.
-            else
-            {
-                s = new StringSerializer(ctx);
-            }
+        // Check if the type exists in the map
+        var serializer = _serializerMap
+            .Where(entry => entry.Key.IsAssignableFrom(objectType))
+            .Select(entry => entry.Value(ctx))
+            .FirstOrDefault();
 
-            return s;
-        }
-        return null;
+        // Return the found serializer or default to a string serializer
+        return serializer ?? new StringSerializer(ctx);
     }
-}
+}