Generate switch expression

Author: danielmarbach

sdk/eventgrid/Azure.Messaging.EventGrid/EventGridSourceGenerator/src/EventGridSourceGenerator.cs

@@ -109,28 +109,21 @@ internal class SystemEventExtensions
     {{
         public static object AsSystemEventData(string eventType, JsonElement data)
         {{
-            if (s_systemEventDeserializers.TryGetValue(eventType, out Func<JsonElement,{(_isSystemEventsLibrary ? " ModelReaderWriterOptions," : string.Empty)} object> systemDeserializationFunction))
+            return eventType switch
             {{
-                return systemDeserializationFunction(data{(_isSystemEventsLibrary ? ", null" : string.Empty)});
-            }}
-            else
-            {{
-                return null;
-            }}
-        }}
-
-        internal static readonly IReadOnlyDictionary<string, Func<JsonElement,{(_isSystemEventsLibrary ? " ModelReaderWriterOptions," : string.Empty)} object>> s_systemEventDeserializers = new Dictionary<string, Func<JsonElement,{(_isSystemEventsLibrary ? " ModelReaderWriterOptions," : string.Empty)} object>>(StringComparer.OrdinalIgnoreCase)
-        {{
 ");
             foreach (SystemEventNode sysEvent in _visitor.SystemEvents)
             {
                 // Add each an entry for each system event to the dictionary containing a mapping from constant name to deserialization method.
                 sourceBuilder.AppendLine(
-                    $"{Indent}{Indent}{Indent}{{ SystemEventNames.{sysEvent.EventConstantName}, {sysEvent.EventName}.{sysEvent.DeserializeMethod} }},");
+                    $"{Indent}{Indent}{Indent}{Indent}SystemEventNames.{sysEvent.EventConstantName} => {sysEvent.EventName}.{sysEvent.DeserializeMethod}(data{(_isSystemEventsLibrary ? ", null": string.Empty)}),");
             }
-            sourceBuilder.Append($@"{Indent}{Indent}}};
-{Indent}}}
-}}");
+            sourceBuilder.AppendLine($"{Indent}{Indent}{Indent}{Indent}_ => null");
+            sourceBuilder.AppendLine($"{Indent}{Indent}{Indent}}};");
+            sourceBuilder.AppendLine($"{Indent}{Indent}}}");
+            sourceBuilder.AppendLine($"{Indent}}}");
+            sourceBuilder.AppendLine("}");
+
             return sourceBuilder.ToString();
         }
     }