- Reintroduce support for WrapperList third party types.

- Small update to readme to indicate this library is an incremental source generator.

Author: CodingFlow

DecoratorGenerator/Main.cs

@@ -3,6 +3,7 @@
 using Microsoft.CodeAnalysis.Text;
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Text;
 using System.Threading;
 
@@ -18,7 +19,10 @@ public void Initialize(IncrementalGeneratorInitializationContext context) {
                 transform: GetSemanticTargetForGeneration
             );
 
+            var thirdPartyTypes = context.CompilationProvider.SelectMany(GetThirdPartySemanticTargetsForGeneration);
+
             context.RegisterSourceOutput(types, Execute);
+            context.RegisterSourceOutput(thirdPartyTypes, Execute);
         }
 
         private static bool IsSyntaxTargetForGeneration(SyntaxNode syntaxNode, CancellationToken token) {
@@ -37,5 +41,41 @@ private static void Execute(SourceProductionContext context, INamedTypeSymbol ty
 
             context.AddSource($"{className}.generated.cs", SourceText.From(source, Encoding.UTF8, SourceHashAlgorithm.Sha256));
         }
+
+        private IEnumerable<INamedTypeSymbol> GetThirdPartySemanticTargetsForGeneration(Compilation compilation, CancellationToken _) {
+            var wrapperSymbolWithoutNamespace = compilation.Assembly.GetTypeByMetadataName("WrapperList");
+
+            var wrapperListTypes =
+            (wrapperSymbolWithoutNamespace == null)
+            ? GetAllTypes(compilation.Assembly.GlobalNamespace, x => x.Name == "WrapperList")
+            : new[] { wrapperSymbolWithoutNamespace };
+
+            return
+                wrapperListTypes.SelectMany(x => x.GetMembers()
+                .Where(m => m.Name != ".ctor")
+                .Select(m => m as IFieldSymbol)
+                .Select(f => f.Type)
+                .Select(t => t as INamedTypeSymbol));
+        }
+
+        /// <summary>
+        /// Gets all Types inside the namespace matching the predicate including nested namespaces.
+        /// </summary>
+        /// <param name="input"></param>
+        /// <param name="predicate"></param>
+        /// <returns></returns>
+        private IEnumerable<INamedTypeSymbol> GetAllTypes(INamespaceSymbol input, Func<INamedTypeSymbol, bool> predicate) {
+            foreach (var space in input.GetNamespaceMembers()) {
+                foreach (var item in space.GetTypeMembers()) {
+                    if (predicate(item)) {
+                        yield return item;
+                    }
+                }
+
+                foreach (var nestedItem in GetAllTypes(space, predicate)) {
+                    yield return nestedItem;
+                }
+            }
+        }
     }
 }

README.md

@@ -40,7 +40,7 @@ public interface ICat
 }
 ```
 
-Build the project so the abstract class is generated for the interface. The generated class will be named after the interface, but without the `I` prefix. In this case, since the interface is `ICat` the class will be `CatDecorator`. Then create your decorator class as usual:
+Since this library is an [incremental source generator](https://github.com/dotnet/roslyn/blob/d8c21d64ca958840bdaa2898cb2324397dc57bbb/docs/features/incremental-generators.md), the abstract class should be generated after saving the changes to interface's file. The generated class will be named after the interface, but without the `I` prefix. In this case, since the interface is `ICat` the class will be `CatDecorator`. Then create your decorator class as usual:
 
 ```c#
 namespace SampleLibrary;