1 files changed, 42 insertions, 0 deletions
diff --git a/csharp/ProtoGen/SourceGenerators.cs b/csharp/ProtoGen/SourceGenerators.cs
new file mode 100644
index 00000000..c775e419
--- /dev/null
+++ b/csharp/ProtoGen/SourceGenerators.cs
@@ -0,0 +1,42 @@
+using System;
+using System.Collections.Generic;
+using Google.ProtocolBuffers.Descriptors;
+
+namespace Google.ProtocolBuffers.ProtoGen {
+  internal static class SourceGenerators {
+
+    private static readonly Dictionary<Type, Func<IDescriptor, ISourceGenerator>> GeneratorFactories = new Dictionary<Type, Func<IDescriptor, ISourceGenerator>> {
+      { typeof(FileDescriptor), descriptor => new UmbrellaClassGenerator((FileDescriptor) descriptor) },
+      { typeof(EnumDescriptor), descriptor => new EnumGenerator((EnumDescriptor) descriptor) },
+      { typeof(ServiceDescriptor), descriptor => new ServiceGenerator((ServiceDescriptor) descriptor) },
+      { typeof(MessageDescriptor), descriptor => new MessageGenerator((MessageDescriptor) descriptor) },
+      // For other fields, we have IFieldSourceGenerators.
+      { typeof(FieldDescriptor), descriptor => new ExtensionGenerator((FieldDescriptor) descriptor) }
+    };
+
+    public static IFieldSourceGenerator CreateFieldGenerator(FieldDescriptor field) {
+      switch (field.MappedType) {
+        case MappedType.Message :
+          return field.IsRepeated 
+              ? (IFieldSourceGenerator) new RepeatedMessageFieldGenerator(field)
+              : new MessageFieldGenerator(field);
+        case MappedType.Enum:
+          return field.IsRepeated
+              ? (IFieldSourceGenerator)new RepeatedEnumFieldGenerator(field)
+              : new EnumFieldGenerator(field);
+        default:
+          return field.IsRepeated
+              ? (IFieldSourceGenerator)new RepeatedPrimitiveFieldGenerator(field)
+              : new PrimitiveFieldGenerator(field);
+      }
+    }
+
+    public static ISourceGenerator CreateGenerator<T>(T descriptor) where T : IDescriptor {
+      Func<IDescriptor, ISourceGenerator> factory;
+      if (!GeneratorFactories.TryGetValue(typeof(T), out factory)) {
+        throw new ArgumentException("No generator registered for " + typeof(T).Name);
+      }
+      return factory(descriptor);
+    }
+  }
+}