Established cached version of TypeAccessor for Topic

When evaluating members of the source `Topic` class in `TopicMappingService`, we are almost always operating off of an actual `Topic` class, since subclasses of `Topic` are rare, and mostly used for configuration data. Given that, it doesn't make sense to do a lookup of the `TypeAccessor` for the `Topic` class via the `TypeAccessorCache` every time we need to do this (e.g., as part of `GetValue()` and `TryGetCompatibleValue()`. This lookup was probably fast, but there's no need to repeat it when we have a logical default.

Author: JeremyCaney

OnTopic/Mapping/TopicMappingService.cs

@@ -30,6 +30,7 @@ public class TopicMappingService : ITopicMappingService {
     \-------------------------------------------------------------------------------------------------------------------------*/
     readonly                    ITopicRepository                _topicRepository;
     readonly                    ITypeLookupService              _typeLookupService;
+    static readonly             TypeAccessor                    _topicTypeAccessor              = TypeAccessorCache.GetTypeAccessor<Topic>();
 
     /*==========================================================================================================================
     | CONSTRUCTOR
@@ -600,7 +601,8 @@ await MapAsync(
       /*------------------------------------------------------------------------------------------------------------------------
       | Attempt to retrieve value from topic.Get{Property}()
       \-----------------------------------------------------------------------------------------------------------------------*/
-      var typeAccessor          = TypeAccessorCache.GetTypeAccessor(source.GetType());
+      var typeAccessor          = GetTopicAccessor(source.GetType());
+
       var attributeValue        = typeAccessor.GetMethodValue(source, $"Get{configuration.AttributeKey}")?.ToString();
 
       /*------------------------------------------------------------------------------------------------------------------------
@@ -1071,7 +1073,7 @@ private static bool TryGetCompatibleProperty(Topic source, Type targetType, Item
       /*------------------------------------------------------------------------------------------------------------------------
       | Attempt to retrieve value from topic.{Property}
       \-----------------------------------------------------------------------------------------------------------------------*/
-      var sourcePropertyAccessor = TypeAccessorCache.GetTypeAccessor(source.GetType()).GetMember(configuration.AttributeKey);
+      var sourcePropertyAccessor = GetTopicAccessor(source.GetType()).GetMember(configuration.AttributeKey);
 
       /*------------------------------------------------------------------------------------------------------------------------
       | Escape clause if preconditions are not met
@@ -1090,5 +1092,16 @@ private static bool TryGetCompatibleProperty(Topic source, Type targetType, Item
 
     }
 
+    /*==========================================================================================================================
+    | PRIVATE: GET TOPIC ACCESSOR
+    \-------------------------------------------------------------------------------------------------------------------------*/
+    /// <summary>
+    ///   Given a specific <see cref="Type"/> for a <see cref="Topic"/>, returns the appropriate <see cref="TypeAccessor"/> from
+    ///   the <see cref="TypeAccessorCache"/>.
+    /// </summary>
+    /// <param name="topicType">The <see cref="Type"/> of the source <see cref="Topic"/>.</param>
+    private static TypeAccessor GetTopicAccessor(Type topicType) =>
+      topicType == typeof(Topic) ? _topicTypeAccessor : TypeAccessorCache.GetTypeAccessor(topicType);
+
   } //Class
 } //Namespace