Add support for treating a non-abstract type as abstract

Author: mythz

src/ServiceStack.Text/JsConfig.cs

@@ -538,6 +538,8 @@ public static DeserializationErrorDelegate OnDeserializationError
 
         public static HashSet<Type> TreatValueAsRefTypes = new HashSet<Type>();
 
+        public static HashSet<Type> TreatAsAbstractType = new HashSet<Type>();
+
         private static bool? sPreferInterfaces;
         /// <summary>
         /// If set to true, Interface types will be prefered over concrete types when serializing.
@@ -713,6 +715,7 @@ public static void Reset()
             HasSerializeFn = new HashSet<Type>();
             HasIncludeDefaultValue = new HashSet<Type>();
             TreatValueAsRefTypes = new HashSet<Type> { typeof(KeyValuePair<,>) };
+            TreatAsAbstractType = new HashSet<Type>();
             sPropertyConvention = null;
             sExcludePropertyReferences = null;
             sExcludeTypes = new HashSet<Type> { typeof(Stream) };
@@ -769,6 +772,23 @@ public class JsConfig<T>
         /// </summary>
         public static bool? ExcludeTypeInfo = null;
 
+        /// <summary>
+        /// Treat non-abstract type like an abstract type
+        /// </summary>
+        public static bool TreatAsAbstractType
+        {
+            get { return JsConfig.TreatAsAbstractType.Contains(typeof(T)); }
+            set
+            {
+                if (value)
+                    JsConfig.TreatAsAbstractType.Add(typeof(T));
+                else
+                    JsConfig.TreatAsAbstractType.Remove(typeof(T));
+
+                ClearFnCaches();
+            }
+        }
+
         /// <summary>
         /// <see langword="true"/> if the <see cref="ITypeSerializer"/> is configured
         /// to take advantage of <see cref="CLSCompliantAttribute"/> specification,

src/ServiceStack.Text/ReflectionExtensions.cs

@@ -1539,9 +1539,9 @@ public static bool IsStandardClass(this Type type)
         public static bool IsAbstract(this Type type)
         {
 #if (NETFX_CORE || PCL)
-            return type.GetTypeInfo().IsAbstract;
+            return type.GetTypeInfo().IsAbstract || JsConfig.TreatAsAbstractType.Contains(type);
 #else
-            return type.IsAbstract;
+            return type.IsAbstract || JsConfig.TreatAsAbstractType.Contains(type);
 #endif
         }