Implemented GeneratedExtension, although list handling may be incorrect.

csharp/ProtocolBuffers.Test/TestProtos/UnitTestMessageSetProtoFile.cs

@@ -522,8 +522,8 @@ namespace Google.ProtocolBuffers.TestProtos {
     
     #region Nested types
     public static class Types {
-      public static readonly pb::GeneratedExtension<self::TestMessageSet, self::TestMessageSetExtension1> MessageSetExtension =
-            pb::GeneratedExtension.CreateExtension<self::TestMessageSet, self::TestMessageSetExtension1>(Descriptor.Extensions[0]);
+      public static readonly pb::GeneratedExtensionBase<self::TestMessageSet, self::TestMessageSetExtension1> MessageSetExtension =
+            pb::GeneratedSingleExtension<self::TestMessageSet, self::TestMessageSetExtension1>.CreateInstance(Descriptor.Extensions[0]);
     }
     #endregion
     
@@ -731,8 +731,8 @@ namespace Google.ProtocolBuffers.TestProtos {
     
     #region Nested types
     public static class Types {
-      public static readonly pb::GeneratedExtension<self::TestMessageSet, self::TestMessageSetExtension2> MessageSetExtension =
-            pb::GeneratedExtension.CreateExtension<self::TestMessageSet, self::TestMessageSetExtension2>(Descriptor.Extensions[0]);
+      public static readonly pb::GeneratedExtensionBase<self::TestMessageSet, self::TestMessageSetExtension2> MessageSetExtension =
+            pb::GeneratedSingleExtension<self::TestMessageSet, self::TestMessageSetExtension2>.CreateInstance(Descriptor.Extensions[0]);
     }
     #endregion
     

csharp/ProtocolBuffers.Test/TestProtos/UnitTestOptimizeForProtoFile.cs

@@ -81,8 +81,8 @@ namespace Google.ProtocolBuffers.TestProtos {
     
     #region Nested types
     public static class Types {
-      public static readonly pb::GeneratedExtension<self::TestOptimizedForSize, int> TestExtension =
-            pb::GeneratedExtension.CreateExtension<self::TestOptimizedForSize, int>(Descriptor.Extensions[0]);
+      public static readonly pb::GeneratedExtensionBase<self::TestOptimizedForSize, int> TestExtension =
+            pb::GeneratedSingleExtension<self::TestOptimizedForSize, int>.CreateInstance(Descriptor.Extensions[0]);
     }
     #endregion
     

csharp/ProtocolBuffers/ExtendableMessage.cs

@@ -15,21 +15,21 @@ namespace Google.ProtocolBuffers {
     /// <summary>
     /// Checks if a singular extension is present.
     /// </summary>
-    public bool HasExtension(GeneratedExtension<TMessage, TBuilder> extension) {
+    public bool HasExtension(GeneratedExtensionBase<TMessage, TBuilder> extension) {
       return extensions.HasField(extension.Descriptor);
     }
 
     /// <summary>
     /// Returns the number of elements in a repeated extension.
     /// </summary>
-    public int GetExtensionCount<TExtension>(GeneratedExtension<TMessage, IList<TExtension>> extension) {
+    public int GetExtensionCount<TExtension>(GeneratedExtensionBase<TMessage, IList<TExtension>> extension) {
       return extensions.GetRepeatedFieldCount(extension.Descriptor);
     }
 
     /// <summary>
     /// Returns the value of an extension.
     /// </summary>
-    public TExtension GetExtension<TExtension>(GeneratedExtension<TMessage, TExtension> extension) {
+    public TExtension GetExtension<TExtension>(GeneratedExtensionBase<TMessage, TExtension> extension) {
       object value = extensions[extension.Descriptor];
       if (value == null) {
         return (TExtension) extension.MessageDefaultInstance;
@@ -41,7 +41,7 @@ namespace Google.ProtocolBuffers {
     /// <summary>
     /// Returns one element of a repeated extension.
     /// </summary>
-    public TExtension GetExtension<TExtension>(GeneratedExtension<TMessage, IList<TExtension>> extension, int index) {
+    public TExtension GetExtension<TExtension>(GeneratedExtensionBase<TMessage, IList<TExtension>> extension, int index) {
       return (TExtension) extension.SingularFromReflectionType(extensions[extension.Descriptor, index]);
     }
 

csharp/ProtocolBuffers/ExtensionRegistry.cs

@@ -88,7 +88,7 @@ namespace Google.ProtocolBuffers {
     /// <summary>
     /// Add an extension from a generated file to the registry.
     /// </summary>
-    public void Add<TContainer, TExtension> (GeneratedExtension<TContainer, TExtension> extension) 
+    public void Add<TContainer, TExtension> (GeneratedExtensionBase<TContainer, TExtension> extension) 
         where TContainer : IMessage<TContainer> {
       if (extension.Descriptor.MappedType == MappedType.Message) {
         Add(new ExtensionInfo(extension.Descriptor, extension.MessageDefaultInstance));

csharp/ProtocolBuffers/GeneratedExtension.cs → csharp/ProtocolBuffers/GeneratedExtensionBase.cs

-using Google.ProtocolBuffers.Descriptors;
-using System;
+using System;
 using System.Collections.Generic;
 using System.Reflection;
+using System.Text;
+using Google.ProtocolBuffers.Descriptors;
 
 namespace Google.ProtocolBuffers {
-
-  public static class GeneratedExtension {
-
-    public static GeneratedExtension<TContainer, TExtension> CreateExtension<TContainer, TExtension>(FieldDescriptor descriptor)
-        where TContainer : IMessage<TContainer> {
-      if (descriptor.IsRepeated) {
-        throw new ArgumentException("Must call CreateRepeatedGeneratedExtension() for repeated types.");
-      }
-      return new GeneratedExtension<TContainer, TExtension>(descriptor);
-    }
-
-    public static GeneratedExtension<TContainer, IList<TExtension>> CreateRepeatedExtension<TContainer, TExtension>(FieldDescriptor descriptor) 
-        where TContainer : IMessage<TContainer> {
-      if (descriptor.IsRepeated) {
-        throw new ArgumentException("Must call CreateRepeatedGeneratedExtension() for repeated types.");
-      }
-      return new GeneratedExtension<TContainer, IList<TExtension>>(descriptor);
-    }
-  }
-
   /// <summary>
-  /// Base class for all generated extensions.
+  /// Base type for all generated extensions.
   /// </summary>
   /// <remarks>
   /// The protocol compiler generates a static singleton instance of this
@@ -39,42 +20,32 @@ namespace Google.ProtocolBuffers {
   ///   optional int32 bar;
   /// }
   /// </code>
-  /// Then MyProto.Foo.Bar has type GeneratedExtension&lt;MyProto.Foo,int&gt;.
+  /// Then MyProto.Foo.Bar has type GeneratedExtensionBase&lt;MyProto.Foo,int&gt;.
   /// <para />
   /// In general, users should ignore the details of this type, and
-  /// simply use the static singletons as parmaeters to the extension accessors
+  /// simply use the static singletons as parameters to the extension accessors
   /// in ExtendableMessage and ExtendableBuilder.
+  /// The interface implemented by both GeneratedException and GeneratedRepeatException,
+  /// to make it easier to cope with repeats separately.
   /// </remarks>
-  public class GeneratedExtension<TContainer, TExtension> where TContainer : IMessage<TContainer> {
-    private readonly IMessage messageDefaultInstance;
+  public abstract class GeneratedExtensionBase<TContainer, TExtension> {
+
     private readonly FieldDescriptor descriptor;
+    private readonly IMessage messageDefaultInstance;
 
-    internal GeneratedExtension(FieldDescriptor descriptor) {
+    protected GeneratedExtensionBase(FieldDescriptor descriptor) {
       if (!descriptor.IsExtension) {
         throw new ArgumentException("GeneratedExtension given a regular (non-extension) field.");
       }
 
       this.descriptor = descriptor;
-
-      switch (descriptor.MappedType) {
-        case MappedType.Message:
-          PropertyInfo defaultInstanceProperty = typeof(TExtension)
-              .GetProperty("DefaultInstance", BindingFlags.Static | BindingFlags.Public);
-          if (defaultInstanceProperty == null) {
-            throw new ArgumentException("No public static DefaultInstance property for type " + typeof(TExtension).Name);
-          }
-          messageDefaultInstance = (IMessage) defaultInstanceProperty.GetValue(null, null);
-          break;
-        case MappedType.Enum:
-          // FIXME(jonskeet): May not need this
-          //enumValueOf = getMethodOrDie(type, "valueOf",
-            //                           EnumValueDescriptor.class);
-          //enumGetValueDescriptor = getMethodOrDie(type, "getValueDescriptor");
-          messageDefaultInstance = null;
-          break;
-        default:
-          messageDefaultInstance = null;
-          break;
+      if (descriptor.MappedType == MappedType.Message) {
+        PropertyInfo defaultInstanceProperty = typeof(TExtension)
+            .GetProperty("DefaultInstance", BindingFlags.Static | BindingFlags.Public);
+        if (defaultInstanceProperty == null) {
+          throw new ArgumentException("No public static DefaultInstance property for type " + typeof(TExtension).Name);
+        }
+        messageDefaultInstance = (IMessage)defaultInstanceProperty.GetValue(null, null);
       }
     }
 
@@ -82,16 +53,36 @@ namespace Google.ProtocolBuffers {
       get { return descriptor; }
     }
 
+    /// <summary>
+    /// Returns the default message instance for extensions which are message types.
+    /// </summary>
     public IMessage MessageDefaultInstance {
       get { return messageDefaultInstance; }
     }
 
-    internal object SingularFromReflectionType(object p) {
-      throw new System.NotImplementedException();
+    public object SingularFromReflectionType(object value) {
+      switch (Descriptor.MappedType) {
+        case MappedType.Message:
+          if (value is TExtension) {
+            return value;
+          } else {
+            // It seems the copy of the embedded message stored inside the
+            // extended message is not of the exact type the user was
+            // expecting.  This can happen if a user defines a
+            // GeneratedExtension manually and gives it a different type.
+            // This should not happen in normal use.  But, to be nice, we'll
+            // copy the message to whatever type the caller was expecting.
+            return MessageDefaultInstance.CreateBuilderForType()
+                           .MergeFrom((IMessage)value).Build();
+          }
+        case MappedType.Enum:
+          // Just return a boxed int - that can be unboxed to the enum
+          return ((EnumValueDescriptor) value).Number;
+        default:
+          return value;
+      }
     }
 
-    internal object FromReflectionType(object value) {
-      throw new System.NotImplementedException();
-    }
+    public abstract object FromReflectionType(object value);
   }
-}
+}
\ No newline at end of file

csharp/ProtocolBuffers/GeneratedRepeatException.cs

+using System;
+using System.Collections.Generic;
+using Google.ProtocolBuffers.Descriptors;
+using System.Collections;
+
+namespace Google.ProtocolBuffers {
+  /// <summary>
+  /// Class used to represent repeat extensions in generated classes.
+  /// </summary>
+  public class GeneratedRepeatExtension<TContainer, TExtensionElement> : GeneratedExtensionBase<TContainer, IList<TExtensionElement>> {
+    private GeneratedRepeatExtension(FieldDescriptor field) : base(field) {
+    }
+
+    public static GeneratedExtensionBase<TContainer, IList<TExtensionElement>> CreateInstance(FieldDescriptor descriptor) {
+      if (descriptor.IsRepeated) {
+        throw new ArgumentException("Must call GeneratedRepeatExtension.CreateInstance() for repeated types.");
+      }
+      return new GeneratedRepeatExtension<TContainer, TExtensionElement>(descriptor);
+    }
+
+    /// <summary>
+    /// Converts the list to the right type.
+    /// TODO(jonskeet): Check where this is used, and whether we need to convert
+    /// for primitive types.
+    /// </summary>
+    /// <param name="value"></param>
+    /// <returns></returns>
+    public override object FromReflectionType(object value) {
+      if (Descriptor.MappedType == MappedType.Message ||
+          Descriptor.MappedType == MappedType.Enum) {
+        // Must convert the whole list.
+        List<TExtensionElement> result = new List<TExtensionElement>();
+        foreach (object element in (IEnumerable) value) {
+          ((IList) result).Add(SingularFromReflectionType(element));
+        }
+        return result;
+      } else {
+        return value;
+      }
+    }
+  }
+}

csharp/ProtocolBuffers/GeneratedSingleExtension.cs

+using System;
+using Google.ProtocolBuffers.Descriptors;
+
+namespace Google.ProtocolBuffers {
+
+  /// <summary>
+  /// Generated extension for a singular field.
+  /// </remarks>
+  public class GeneratedSingleExtension<TContainer, TExtension> : GeneratedExtensionBase<TContainer, TExtension>    
+      where TContainer : IMessage<TContainer> {
+
+    internal GeneratedSingleExtension(FieldDescriptor descriptor) : base(descriptor) {
+    }
+
+    public static GeneratedSingleExtension<TContainer, TExtension> CreateInstance(FieldDescriptor descriptor) {
+      if (descriptor.IsRepeated) {
+        throw new ArgumentException("Must call GeneratedRepeateExtension.CreateInstance() for repeated types.");
+      }
+      return new GeneratedSingleExtension<TContainer, TExtension>(descriptor);
+    }
+
+    public override object FromReflectionType(object value) {
+      return base.SingularFromReflectionType(value);
+    }
+  }
+}

csharp/ProtocolBuffers/ProtocolBuffers.csproj

@@ -82,9 +82,11 @@
     <Compile Include="FieldAccess\RepeatedMessageAccessor.cs" />
     <Compile Include="FieldSet.cs" />
     <Compile Include="GeneratedBuilder.cs" />
-    <Compile Include="GeneratedExtension.cs" />
+    <Compile Include="GeneratedSingleExtension.cs" />
     <Compile Include="GeneratedMessage.cs" />
+    <Compile Include="GeneratedRepeatException.cs" />
     <Compile Include="IBuilder.cs" />
+    <Compile Include="GeneratedExtensionBase.cs" />
     <Compile Include="IMessage.cs" />
     <Compile Include="InvalidProtocolBufferException.cs" />
     <Compile Include="IRpcChannel.cs" />

src/google/protobuf/compiler/csharp/csharp_extension.cc

@@ -57,12 +57,12 @@ void ExtensionGenerator::Generate(io::Printer* printer) {
   if (descriptor_->is_repeated()) {
     printer->Print(vars,
       "public static readonly\r\n"
-      "  pb::GeneratedExtension<$containing_type$, scg::IList<$type$>> name =\r\n"
-      "      pb::GeneratedExtension.CreateRepeatedExtension<$containing_type$, $type$>(Descriptor.Extensions[$index$]);\r\n");
+      "  pb::GeneratedExtensionBase<$containing_type$, scg::IList<$type$>> name =\r\n"
+      "      pb::GeneratedRepeatExtension<$containing_type$, $type$>.CreateInstance(Descriptor.Extensions[$index$]);\r\n");
   } else {
     printer->Print(vars,
-      "public static readonly pb::GeneratedExtension<$containing_type$, $type$> $name$ =\r\n"
-      "      pb::GeneratedExtension.CreateExtension<$containing_type$, $type$>(Descriptor.Extensions[$index$]);\r\n");
+      "public static readonly pb::GeneratedExtensionBase<$containing_type$, $type$> $name$ =\r\n"
+      "      pb::GeneratedSingleExtension<$containing_type$, $type$>.CreateInstance(Descriptor.Extensions[$index$]);\r\n");
   }
 }