Added DynamicMessage and ExtendableBuilder, along with the first supporting tests.

csharp/ProtocolBuffers.Test/CodedInputStreamTest.cs

@@ -275,64 +275,64 @@ namespace Google.ProtocolBuffers {
       }
     }
     
-    
-    /* TODO(jonskeet): Reinstate this when protoc is ready
-    private TestRecursiveMessage makeRecursiveMessage(int depth) {
+    private static TestRecursiveMessage MakeRecursiveMessage(int depth) {
       if (depth == 0) {
-        return TestRecursiveMessage.newBuilder().setI(5).build();
+        return TestRecursiveMessage.CreateBuilder().SetI(5).Build();
       } else {
-        return TestRecursiveMessage.newBuilder()
-          .setA(makeRecursiveMessage(depth - 1)).build();
+        return TestRecursiveMessage.CreateBuilder()
+          .SetA(MakeRecursiveMessage(depth - 1)).Build();
       }
     }
 
-    private void assertMessageDepth(TestRecursiveMessage message, int depth) {
+    private static void AssertMessageDepth(TestRecursiveMessage message, int depth) {
       if (depth == 0) {
-        assertFalse(message.hasA());
-        assertEquals(5, message.getI());
+        Assert.IsFalse(message.HasA);
+        Assert.AreEqual(5, message.I);
       } else {
-        assertTrue(message.hasA());
-        assertMessageDepth(message.getA(), depth - 1);
+        Assert.IsTrue(message.HasA);
+        AssertMessageDepth(message.A, depth - 1);
       }
     }
 
-    public void testMaliciousRecursion() {
-      ByteString data64 = makeRecursiveMessage(64).toByteString();
-      ByteString data65 = makeRecursiveMessage(65).toByteString();
+    [Test]
+    public void MaliciousRecursion() {
+      ByteString data64 = MakeRecursiveMessage(64).ToByteString();
+      ByteString data65 = MakeRecursiveMessage(65).ToByteString();
 
-      assertMessageDepth(TestRecursiveMessage.parseFrom(data64), 64);
+      AssertMessageDepth(TestRecursiveMessage.ParseFrom(data64), 64);
 
       try {
-        TestRecursiveMessage.parseFrom(data65);
-        fail("Should have thrown an exception!");
-      } catch (InvalidProtocolBufferException e) {
+        TestRecursiveMessage.ParseFrom(data65);
+        Assert.Fail("Should have thrown an exception!");
+      } catch (InvalidProtocolBufferException) {
         // success.
       }
 
-      CodedInputStream input = data64.newCodedInput();
-      input.setRecursionLimit(8);
+      CodedInputStream input = data64.CreateCodedInput();
+      input.SetRecursionLimit(8);
       try {
-        TestRecursiveMessage.parseFrom(input);
-        fail("Should have thrown an exception!");
-      } catch (InvalidProtocolBufferException e) {
+        TestRecursiveMessage.ParseFrom(input);
+        Assert.Fail("Should have thrown an exception!");
+      } catch (InvalidProtocolBufferException) {
         // success.
       }
     }
-     */
 
-     /* TODO(jonskeet): Reinstate this when protoc is ready
-    public void testSizeLimit() throws Exception {
-      CodedInputStream input = CodedInputStream.newInstance(
-        TestUtil.getAllSet().toByteString().newInput());
-      input.setSizeLimit(16);
+    [Test]
+    public void SizeLimit() {
+      // Have to use a Stream rather than ByteString.CreateCodedInput as SizeLimit doesn't
+      // apply to the latter case.
+      MemoryStream ms = new MemoryStream(TestUtil.GetAllSet().ToByteString().ToByteArray());
+      CodedInputStream input = CodedInputStream.CreateInstance(ms);
+      input.SetSizeLimit(16);
 
       try {
-        TestAllTypes.parseFrom(input);
-        fail("Should have thrown an exception!");
-      } catch (InvalidProtocolBufferException e) {
+        TestAllTypes.ParseFrom(input);
+        Assert.Fail("Should have thrown an exception!");
+      } catch (InvalidProtocolBufferException) {
         // success.
       }
-    }*/
+    }
 
     /// <summary>
     /// Tests that if we read an string that contains invalid UTF-8, no exception

csharp/ProtocolBuffers.Test/CodedOutputStreamTest.cs

@@ -14,6 +14,7 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
+using Google.ProtocolBuffers.TestProtos;
 using NUnit.Framework;
 
 namespace Google.ProtocolBuffers {
@@ -33,6 +34,10 @@ namespace Google.ProtocolBuffers {
       return bytes;
     }
 
+    private static void AssertEqualBytes(byte[] a, byte[] b) {
+      Assert.AreEqual(ByteString.CopyFrom(a), ByteString.CopyFrom(b));
+    }
+
     /// <summary>
     /// Writes the given value using WriteRawVarint32() and WriteRawVarint64() and
     /// checks that the result matches the given bytes
@@ -174,24 +179,23 @@ namespace Google.ProtocolBuffers {
         0x9abcdef012345678UL);
     }
 
-    /* TODO(jonskeet): Put this back when we've got the rest working!
     [Test]
-    public void testWriteWholeMessage() throws Exception {
-      TestAllTypes message = TestUtil.getAllSet();
+    public void WriteWholeMessage() {
+      TestAllTypes message = TestUtil.GetAllSet();
 
-      byte[] rawBytes = message.toByteArray();
-      assertEqualBytes(TestUtil.getGoldenMessage().toByteArray(), rawBytes);
+      byte[] rawBytes = message.ToByteArray();
+      AssertEqualBytes(TestUtil.GoldenMessage.ToByteArray(), rawBytes);
 
       // Try different block sizes.
       for (int blockSize = 1; blockSize < 256; blockSize *= 2) {
         MemoryStream rawOutput = new MemoryStream();
         CodedOutputStream output =
-          CodedOutputStream.newInstance(rawOutput, blockSize);
-        message.writeTo(output);
-        output.flush();
-        assertEqualBytes(rawBytes, rawOutput.toByteArray());
+          CodedOutputStream.CreateInstance(rawOutput, blockSize);
+        message.WriteTo(output);
+        output.Flush();
+        AssertEqualBytes(rawBytes, rawOutput.ToArray());
+      }
     }
-    } */
 
 
     [Test]

csharp/ProtocolBuffers.Test/ProtocolBuffers.Test.csproj

@@ -44,10 +44,12 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="AbstractMessageTest.cs" />
     <Compile Include="ByteStringTest.cs" />
     <Compile Include="CodedInputStreamTest.cs" />
     <Compile Include="CodedOutputStreamTest.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="ReflectionTester.cs" />
     <Compile Include="TestProtos\UnitTestEmbedOptimizeForProtoFile.cs" />
     <Compile Include="TestProtos\UnitTestImportProtoFile.cs" />
     <Compile Include="TestProtos\UnitTestMessageSetProtoFile.cs" />

csharp/ProtocolBuffers.Test/TestProtos/UnitTestEmbedOptimizeForProtoFile.cs

@@ -40,7 +40,6 @@ namespace Google.ProtocolBuffers.TestProtos {
     #endregion
     
     #region Extensions
-    /**/
     #endregion
     
     #region Static variables
@@ -219,6 +218,10 @@ namespace Google.ProtocolBuffers.TestProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::TestEmbedOptimizedForSize) {
           return MergeFrom((self::TestEmbedOptimizedForSize) other);

csharp/ProtocolBuffers.Test/TestProtos/UnitTestImportProtoFile.cs

@@ -34,7 +34,6 @@ namespace Google.ProtocolBuffers.TestProtos {
     #endregion
     
     #region Extensions
-    /**/
     #endregion
     
     #region Static variables
@@ -192,6 +191,10 @@ namespace Google.ProtocolBuffers.TestProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::ImportMessage) {
           return MergeFrom((self::ImportMessage) other);

csharp/ProtocolBuffers.Test/TestProtos/UnitTestMessageSetProtoFile.cs

@@ -55,7 +55,6 @@ namespace Google.ProtocolBuffers.TestProtos {
     #endregion
     
     #region Extensions
-    /**/
     #endregion
     
     #region Static variables
@@ -197,7 +196,7 @@ namespace Google.ProtocolBuffers.TestProtos {
       return (Builder) new Builder().MergeFrom(prototype);
     }
     
-    public sealed partial class Builder : pb::GeneratedBuilder<self::TestMessageSet, self::TestMessageSet.Builder>.ExtendableBuilder {
+    public sealed partial class Builder : pb::ExtendableBuilder<self::TestMessageSet, self::TestMessageSet.Builder> {
       // Construct using self::TestMessageSet.CreateBuilder()
       internal Builder() {}
       
@@ -230,6 +229,10 @@ namespace Google.ProtocolBuffers.TestProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::TestMessageSet) {
           return MergeFrom((self::TestMessageSet) other);
@@ -409,6 +412,10 @@ namespace Google.ProtocolBuffers.TestProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::TestMessageSetContainer) {
           return MergeFrom((self::TestMessageSetContainer) other);
@@ -639,6 +646,10 @@ namespace Google.ProtocolBuffers.TestProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::TestMessageSetExtension1) {
           return MergeFrom((self::TestMessageSetExtension1) other);
@@ -848,6 +859,10 @@ namespace Google.ProtocolBuffers.TestProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::TestMessageSetExtension2) {
           return MergeFrom((self::TestMessageSetExtension2) other);
@@ -1091,6 +1106,10 @@ namespace Google.ProtocolBuffers.TestProtos {
             return returnMe;
           }
           
+          protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+            return MergeFrom(data, extensionRegistry);
+          }
+          
           public override IBuilder MergeFrom(pb::IMessage other) {
             if (other is self::RawMessageSet.Types.Item) {
               return MergeFrom((self::RawMessageSet.Types.Item) other);
@@ -1309,6 +1328,10 @@ namespace Google.ProtocolBuffers.TestProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::RawMessageSet) {
           return MergeFrom((self::RawMessageSet) other);

csharp/ProtocolBuffers.Test/TestProtos/UnitTestOptimizeForProtoFile.cs

@@ -39,7 +39,6 @@ namespace Google.ProtocolBuffers.TestProtos {
     #endregion
     
     #region Extensions
-    /**/
     #endregion
     
     #region Static variables
@@ -146,7 +145,7 @@ namespace Google.ProtocolBuffers.TestProtos {
       return (Builder) new Builder().MergeFrom(prototype);
     }
     
-    public sealed partial class Builder : pb::GeneratedBuilder<self::TestOptimizedForSize, self::TestOptimizedForSize.Builder>.ExtendableBuilder {
+    public sealed partial class Builder : pb::ExtendableBuilder<self::TestOptimizedForSize, self::TestOptimizedForSize.Builder> {
       // Construct using self::TestOptimizedForSize.CreateBuilder()
       internal Builder() {}
       

csharp/ProtocolBuffers/AbstractBuilder.cs

@@ -8,6 +8,7 @@ using System.IO;
 namespace Google.ProtocolBuffers {
   /// <summary>
   /// Implementation of the non-generic IMessage interface as far as possible.
+  /// TODO(jonskeet): Make this generic, to avoid so much casting in DynamicMessage.
   /// </summary>
   public abstract class AbstractBuilder : IBuilder {
     #region Unimplemented members of IBuilder
@@ -57,7 +58,7 @@ namespace Google.ProtocolBuffers {
     }
     #endregion
 
-    public IBuilder Clear() {
+    public virtual IBuilder Clear() {
       foreach(FieldDescriptor field in AllFields.Keys) {
         ClearFieldImpl(field);
       }
@@ -168,5 +169,15 @@ namespace Google.ProtocolBuffers {
     }
 
     public abstract UnknownFieldSet UnknownFields { get; set; }
+    
+    public IBuilder SetField(FieldDescriptor field, object value) {
+      this[field] = value;
+      return this;
+    }
+
+    public IBuilder SetRepeatedField(FieldDescriptor field, int index, object value) {
+      this[field, index] = value;
+      return this;
+    }
   }
 }

csharp/ProtocolBuffers/AbstractMessage.cs

@@ -16,6 +16,7 @@
 using System.Collections;
 using System.Collections.Generic;
 using System.IO;
+using Google.ProtocolBuffers.Collections;
 using Google.ProtocolBuffers.Descriptors;
 
 namespace Google.ProtocolBuffers {
@@ -171,15 +172,13 @@ namespace Google.ProtocolBuffers {
       if (otherMessage == null || otherMessage.DescriptorForType != DescriptorForType) {
         return false;
       }
-      // TODO(jonskeet): Check that dictionaries support equality appropriately
-      // (I suspect they don't!)
-      return AllFields.Equals(otherMessage.AllFields);
+      return Dictionaries.Equals(AllFields, otherMessage.AllFields);
     }
 
     public override int GetHashCode() {
       int hash = 41;
       hash = (19 * hash) + DescriptorForType.GetHashCode();
-      hash = (53 * hash) + AllFields.GetHashCode();
+      hash = (53 * hash) + Dictionaries.GetHashCode(AllFields);
       return hash;
     }
   }

csharp/ProtocolBuffers/Collections/Dictionaries.cs

 using System;
 using System.Collections.Generic;
 using System.Text;
+using System.Collections;
+using Google.ProtocolBuffers.Descriptors;
 
 namespace Google.ProtocolBuffers.Collections {
 
@@ -9,8 +11,85 @@ namespace Google.ProtocolBuffers.Collections {
   /// in the generic class.
   /// </summary>
   public static class Dictionaries {
+
+    /// <summary>
+    /// Compares two dictionaries for equality. Each value is compared with equality using Equals
+    /// for non-IEnumerable implementations, and using EnumerableEquals otherwise.
+    /// TODO(jonskeet): This is clearly pretty slow, and involves lots of boxing/unboxing...
+    /// </summary>
+    public static bool Equals<TKey, TValue>(IDictionary<TKey, TValue> left, IDictionary<TKey, TValue> right) {
+      if (left.Count != right.Count) {
+        return false;
+      }
+      foreach (KeyValuePair<TKey,TValue> leftEntry in left)
+      {
+        TValue rightValue;
+        if (!right.TryGetValue(leftEntry.Key, out rightValue)) {
+          return false;
+        }
+
+        IEnumerable leftEnumerable = leftEntry.Value as IEnumerable;
+        IEnumerable rightEnumerable = rightValue as IEnumerable;
+        if (leftEnumerable == null || rightEnumerable == null) {
+          if (!object.Equals(leftEntry.Value, rightValue)) {
+            return false;
+          }
+        } else {
+          IEnumerator leftEnumerator = leftEnumerable.GetEnumerator();
+          try {
+            foreach (object rightObject in rightEnumerable) {
+              if (!leftEnumerator.MoveNext()) {
+                return false;
+              }
+              if (!object.Equals(leftEnumerator.Current, rightObject)) {
+                return false;
+              }
+            }
+            if (leftEnumerator.MoveNext()) {
+              return false;
+            }
+          } finally {
+            if (leftEnumerator is IDisposable) {
+              ((IDisposable)leftEnumerator).Dispose();
+            }
+          }
+        }
+      }
+      return true;
+    }
+
     public static IDictionary<TKey, TValue> AsReadOnly<TKey, TValue> (IDictionary<TKey, TValue> dictionary) {
       return dictionary.IsReadOnly ? dictionary : new ReadOnlyDictionary<TKey, TValue>(dictionary);
     }
+
+    /// <summary>
+    /// Creates a hashcode for a dictionary by XORing the hashcodes of all the fields
+    /// and values. (By XORing, we avoid ordering issues.)
+    /// TODO(jonskeet): Currently XORs other stuff too, and assumes non-null values.
+    /// </summary>
+    public static int GetHashCode<TKey, TValue>(IDictionary<TKey, TValue> dictionary) {
+      int ret = 31;
+      foreach (KeyValuePair<TKey, TValue> entry in dictionary) {
+        int hash = entry.Key.GetHashCode() ^ GetDeepHashCode(entry.Value);
+        ret ^= hash;
+      }
+      return ret;
+    }
+
+    /// <summary>
+    /// Determines the hash of a value by either taking it directly or hashing all the elements
+    /// for IEnumerable implementations.
+    /// </summary>
+    private static int GetDeepHashCode(object value) {
+      IEnumerable iterable = value as IEnumerable;
+      if (iterable == null) {
+        return value.GetHashCode();
+      }
+      int hash = 29;
+      foreach (object element in iterable) {
+        hash = hash * 37 + element.GetHashCode();
+      }
+      return hash;
+    }
   }
 }

csharp/ProtocolBuffers/DescriptorProtos/DescriptorProtoFile.cs

@@ -161,7 +161,6 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
     #endregion
     
     #region Extensions
-    /**/
     #endregion
     
     #region Static variables
@@ -547,6 +546,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::FileDescriptorProto) {
           return MergeFrom((self::FileDescriptorProto) other);
@@ -1128,6 +1131,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             return returnMe;
           }
           
+          protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+            return MergeFrom(data, extensionRegistry);
+          }
+          
           public override IBuilder MergeFrom(pb::IMessage other) {
             if (other is self::DescriptorProto.Types.ExtensionRange) {
               return MergeFrom((self::DescriptorProto.Types.ExtensionRange) other);
@@ -1459,6 +1466,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::DescriptorProto) {
           return MergeFrom((self::DescriptorProto) other);
@@ -2130,6 +2141,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::FieldDescriptorProto) {
           return MergeFrom((self::FieldDescriptorProto) other);
@@ -2582,6 +2597,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::EnumDescriptorProto) {
           return MergeFrom((self::EnumDescriptorProto) other);
@@ -2919,6 +2938,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::EnumValueDescriptorProto) {
           return MergeFrom((self::EnumValueDescriptorProto) other);
@@ -3231,6 +3254,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::ServiceDescriptorProto) {
           return MergeFrom((self::ServiceDescriptorProto) other);
@@ -3584,6 +3611,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::MethodDescriptorProto) {
           return MergeFrom((self::MethodDescriptorProto) other);
@@ -4022,6 +4053,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::FileOptions) {
           return MergeFrom((self::FileOptions) other);
@@ -4437,6 +4472,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::MessageOptions) {
           return MergeFrom((self::MessageOptions) other);
@@ -4664,6 +4703,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::FieldOptions) {
           return MergeFrom((self::FieldOptions) other);
@@ -4881,6 +4924,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::EnumOptions) {
           return MergeFrom((self::EnumOptions) other);
@@ -5041,6 +5088,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::EnumValueOptions) {
           return MergeFrom((self::EnumValueOptions) other);
@@ -5201,6 +5252,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::ServiceOptions) {
           return MergeFrom((self::ServiceOptions) other);
@@ -5361,6 +5416,10 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return returnMe;
       }
       
+      protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
+        return MergeFrom(data, extensionRegistry);
+      }
+      
       public override IBuilder MergeFrom(pb::IMessage other) {
         if (other is self::MethodOptions) {
           return MergeFrom((self::MethodOptions) other);

csharp/ProtocolBuffers/Descriptors/EnumDescriptor.cs

@@ -43,7 +43,8 @@ namespace Google.ProtocolBuffers.Descriptors {
     /// Finds an enum value by number. If multiple enum values have the
     /// same number, this returns the first defined value with that number.
     /// </summary>
-    internal EnumValueDescriptor FindValueByNumber(int number) {
+    // TODO(jonskeet): Make internal and use InternalsVisibleTo?
+    public EnumValueDescriptor FindValueByNumber(int number) {
       return File.DescriptorPool.FindEnumValueByNumber(this, number);
     }
 
@@ -52,7 +53,8 @@ namespace Google.ProtocolBuffers.Descriptors {
     /// </summary>
     /// <param name="name">The unqualified name of the value (e.g. "FOO").</param>
     /// <returns>The value's descriptor, or null if not found.</returns>
-    internal EnumValueDescriptor FindValueByName(string name) {
+    // TODO(jonskeet): Make internal and use InternalsVisibleTo?
+    public EnumValueDescriptor FindValueByName(string name) {
       return File.DescriptorPool.FindSymbol<EnumValueDescriptor>(FullName + "." + name);
     }
   }

csharp/ProtocolBuffers/ExtendableBuilder.cs

+using System;
+using System.Collections.Generic;
+using System.Text;
+using Google.ProtocolBuffers.Descriptors;
+
+namespace Google.ProtocolBuffers {
+  public abstract class ExtendableBuilder<TMessage, TBuilder> : GeneratedBuilder<TMessage, TBuilder>
+    where TMessage : ExtendableMessage<TMessage, TBuilder>
+    where TBuilder : GeneratedBuilder<TMessage, TBuilder> {
+
+    protected ExtendableBuilder() {}
+
+    /// <summary>
+    /// Checks if a singular extension is present
+    /// </summary>
+    public bool HasExtension<TExtension>(GeneratedExtensionBase<TMessage, TExtension> extension) {
+      return MessageBeingBuilt.HasExtension(extension);
+    }
+
+    /// <summary>
+    /// Returns the number of elements in a repeated extension.
+    /// </summary>
+    public int GetExtensionCount<TExtension>(GeneratedExtensionBase<TMessage, IList<TExtension>> extension) {
+      return MessageBeingBuilt.GetExtensionCount(extension);
+    }
+
+    /// <summary>
+    /// Returns the value of an extension.
+    /// </summary>
+    public TExtension GetExtension<TExtension>(GeneratedExtensionBase<TMessage, TExtension> extension) {
+      return MessageBeingBuilt.GetExtension(extension);
+    }
+
+    /// <summary>
+    /// Returns one element of a repeated extension.
+    /// </summary>
+    public TExtension GetExtension<TExtension>(GeneratedExtensionBase<TMessage, IList<TExtension>> extension, int index) {
+      return MessageBeingBuilt.GetExtension(extension, index);
+    }
+
+    /// <summary>
+    /// Sets the value of an extension.
+    /// </summary>
+    public ExtendableBuilder<TMessage, TBuilder> SetExtension<TExtension>(GeneratedExtensionBase<TMessage, TExtension> extension, TExtension value) {
+      ExtendableMessage<TMessage, TBuilder> message = MessageBeingBuilt;
+      message.VerifyExtensionContainingType(extension);
+      message.Extensions[extension.Descriptor] = extension.ToReflectionType(value);
+      return this;
+    }
+
+    /// <summary>
+    /// Sets the value of one element of a repeated extension.
+    /// </summary>
+    public ExtendableBuilder<TMessage, TBuilder> SetExtension<TExtension>(
+        GeneratedExtensionBase<TMessage, IList<TExtension>> extension, int index, Type value) {
+      ExtendableMessage<TMessage, TBuilder> message = MessageBeingBuilt;
+      message.VerifyExtensionContainingType(extension);
+      message.Extensions[extension.Descriptor, index] = extension.SingularToReflectionType(value);
+      return this;
+    }
+
+    /// <summary>
+    /// Appends a value to a repeated extension.
+    /// </summary>
+    public ExtendableBuilder<TMessage, TBuilder> AddExtension<TExtension>(
+        GeneratedExtensionBase<TMessage, IList<TExtension>> extension, TExtension value) {
+      ExtendableMessage<TMessage, TBuilder> message = MessageBeingBuilt;
+      message.VerifyExtensionContainingType(extension);
+      message.Extensions.AddRepeatedField(extension.Descriptor, extension.SingularToReflectionType(value));
+      return this;
+    }
+
+    /// <summary>
+    /// Clears an extension.
+    /// </summary>
+    public ExtendableBuilder<TMessage, TBuilder> ClearExtension<TExtension>(
+        GeneratedExtensionBase<TMessage, TExtension> extension) {
+      ExtendableMessage<TMessage, TBuilder> message = MessageBeingBuilt;
+      message.VerifyExtensionContainingType(extension);
+      message.Extensions.ClearField(extension.Descriptor);
+      return this;
+    }
+
+    /// <summary>
+    /// Called by subclasses to parse an unknown field or an extension.
+    /// </summary>
+    /// <returns>true unless the tag is an end-group tag</returns>
+    protected override bool ParseUnknownField(CodedInputStream input, UnknownFieldSet.Builder unknownFields,
+        ExtensionRegistry extensionRegistry, uint tag) {
+      return FieldSet.MergeFieldFrom(input, unknownFields, extensionRegistry, this, tag);
+    }
+
+    // ---------------------------------------------------------------
+    // Reflection
+
+
+    public override object this[FieldDescriptor field, int index] {
+      set {
+        if (field.IsExtension) {
+          ExtendableMessage<TMessage, TBuilder> message = MessageBeingBuilt;
+          // TODO(jonskeet): Figure out how to call this!
+          // message.VerifyExtensionContainingType(field);
+          message.Extensions[field, index] = value;
+        } else {
+          base[field, index] = value;
+        }
+      }
+    }
+
+    
+    public override object this[FieldDescriptor field] {
+      set {
+        if (field.IsExtension) {
+          ExtendableMessage<TMessage, TBuilder> message = MessageBeingBuilt;
+          // TODO(jonskeet): Figure out how to call this!
+          // message.VerifyExtensionContainingType(field);
+          message.Extensions[field] = value;
+        } else {
+          base[field] = value;
+        }
+        InternalFieldAccessors[field].SetValue(this, value);
+      }
+    }
+
+    public override IBuilder<TMessage> ClearField(FieldDescriptor field) {
+      if (field.IsExtension) {
+        ExtendableMessage<TMessage, TBuilder> message = MessageBeingBuilt;
+        message.VerifyContainingType(field);
+        message.Extensions.ClearField(field);
+        return this;
+      } else {
+        return base.ClearField(field);
+      }
+    }
+
+    public override IBuilder<TMessage> AddRepeatedField(FieldDescriptor field, object value) {
+      if (field.IsExtension) {
+        ExtendableMessage<TMessage, TBuilder> message = MessageBeingBuilt;
+        message.VerifyContainingType(field); 
+        message.Extensions.AddRepeatedField(field, value);
+        return this;
+      } else {
+        return base.AddRepeatedField(field, value);
+      }
+    }
+  }
+}

csharp/ProtocolBuffers/ExtendableMessage.cs

@@ -12,10 +12,17 @@ namespace Google.ProtocolBuffers {
     protected ExtendableMessage() {}
     private readonly FieldSet extensions = FieldSet.CreateFieldSet();
 
+    /// <summary>
+    /// Access for the builder.
+    /// </summary>
+    internal FieldSet Extensions {
+      get { return extensions; }
+    }
+
     /// <summary>
     /// Checks if a singular extension is present.
     /// </summary>
-    public bool HasExtension(GeneratedExtensionBase<TMessage, TBuilder> extension) {
+    public bool HasExtension<TExtension>(GeneratedExtensionBase<TMessage, TExtension> extension) {
       return extensions.HasField(extension.Descriptor);
     }
 
@@ -111,7 +118,7 @@ namespace Google.ProtocolBuffers {
       }
     }
   
-    private void VerifyContainingType(FieldDescriptor field) {
+    internal void VerifyContainingType(FieldDescriptor field) {
       if (field.ContainingType != DescriptorForType) {
         throw new ArgumentException("FieldDescriptor does not match message type.");
       }
@@ -161,5 +168,13 @@ namespace Google.ProtocolBuffers {
     protected int ExtensionsSerializedSize {
       get { return extensions.SerializedSize; }
     }
+
+    internal void VerifyExtensionContainingType<TExtension>(GeneratedExtensionBase<TMessage, TExtension> extension) {
+      if (extension.Descriptor.ContainingType != DescriptorForType) {
+        // This can only happen if someone uses unchecked operations.
+        throw new ArgumentException("Extension is for type \"" + extension.Descriptor.ContainingType.FullName
+          + "\" which does not match message type \"" + DescriptorForType.FullName + "\".");
+      }
+    }
   }
 }

csharp/ProtocolBuffers/FieldAccess/RepeatedPrimitiveAccessor.cs

@@ -73,7 +73,7 @@ namespace Google.ProtocolBuffers.FieldAccess {
     }
 
     public int GetRepeatedCount(IMessage message) {
-      return (int) countProperty.GetValue(null, null);
+      return (int) countProperty.GetValue(message, null);
     }
 
     public virtual object GetRepeatedValue(IMessage message, int index) {

csharp/ProtocolBuffers/GeneratedBuilder.cs

@@ -65,7 +65,7 @@ namespace Google.ProtocolBuffers {
     /// Called by derived classes to parse an unknown field.
     /// </summary>
     /// <returns>true unless the tag is an end-group tag</returns>
-    protected bool ParseUnknownField(CodedInputStream input, UnknownFieldSet.Builder unknownFields,
+    protected virtual bool ParseUnknownField(CodedInputStream input, UnknownFieldSet.Builder unknownFields,
                                      ExtensionRegistry extensionRegistry, uint tag) {
       return unknownFields.MergeFieldFrom(tag, input);
     }
@@ -115,7 +115,7 @@ namespace Google.ProtocolBuffers {
       return AddRepeatedField(field, value);
     }
 
-    public IBuilder<TMessage> ClearField(FieldDescriptor field) {
+    public virtual IBuilder<TMessage> ClearField(FieldDescriptor field) {
       InternalFieldAccessors[field].Clear(this);
       return this;
     }
@@ -155,7 +155,7 @@ namespace Google.ProtocolBuffers {
       return this;
     }
 
-    public IBuilder<TMessage> AddRepeatedField(FieldDescriptor field, object value) {
+    public virtual IBuilder<TMessage> AddRepeatedField(FieldDescriptor field, object value) {
       InternalFieldAccessors[field].AddRepeated(this, value);
       return this;
     }
@@ -190,20 +190,22 @@ namespace Google.ProtocolBuffers {
       return this;
     }
 
+    /// <summary>
+    /// Overridden when optimized for speed.
+    /// </summary>
     public virtual IBuilder<TMessage> MergeFrom(CodedInputStream input) {
       ((IBuilder)this).MergeFrom(input);
       return this;
     }
 
+    /// <summary>
+    /// Overridden when optimized for speed.
+    /// </summary>
     public virtual IBuilder<TMessage> MergeFrom(CodedInputStream input, ExtensionRegistry extensionRegistry) {
       ((IBuilder)this).MergeFrom(input, extensionRegistry);
       return this;
     }
     
-    protected override IBuilder MergeFromImpl(CodedInputStream data, ExtensionRegistry extensionRegistry) {
-      return MergeFrom(data, extensionRegistry);
-    }
-    
     /// <summary>
     /// Like Build(), but will wrap UninitializedMessageException in
     /// InvalidProtocolBufferException.

csharp/ProtocolBuffers/GeneratedExtensionBase.cs

 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Reflection;
 using System.Text;
@@ -33,14 +34,14 @@ namespace Google.ProtocolBuffers {
     private readonly FieldDescriptor descriptor;
     private readonly IMessage messageDefaultInstance;
 
-    protected GeneratedExtensionBase(FieldDescriptor descriptor) {
+    protected GeneratedExtensionBase(FieldDescriptor descriptor, Type singularExtensionType) {
       if (!descriptor.IsExtension) {
         throw new ArgumentException("GeneratedExtension given a regular (non-extension) field.");
       }
 
       this.descriptor = descriptor;
       if (descriptor.MappedType == MappedType.Message) {
-        PropertyInfo defaultInstanceProperty = typeof(TExtension)
+        PropertyInfo defaultInstanceProperty = singularExtensionType
             .GetProperty("DefaultInstance", BindingFlags.Static | BindingFlags.Public);
         if (defaultInstanceProperty == null) {
           throw new ArgumentException("No public static DefaultInstance property for type " + typeof(TExtension).Name);
@@ -83,6 +84,38 @@ namespace Google.ProtocolBuffers {
       }
     }
 
+    /// <summary>
+    /// Converts from the type used by the native accessors to the type
+    /// used by reflection accessors. For example, the reflection accessors
+    /// for enums use EnumValueDescriptors but the native accessors use
+    /// the generated enum type.
+    /// </summary>
+    public object ToReflectionType(object value) {
+      if (descriptor.IsRepeated) {
+        if (descriptor.MappedType == MappedType.Enum) {
+          // Must convert the whole list.
+          IList<object> result = new List<object>();
+          foreach (object element in (IEnumerable) value) {
+            result.Add(SingularToReflectionType(element));
+          }
+          return result;
+        } else {
+          return value;
+        }
+      } else {
+        return SingularToReflectionType(value);
+      }
+    }
+
+    /// <summary>
+    /// Like ToReflectionType(object) but for a single element.
+    /// </summary>
+    internal Object SingularToReflectionType(object value) {
+      return descriptor.MappedType == MappedType.Enum
+          ? descriptor.EnumType.FindValueByNumber((int) value)
+          : value;
+    }
+
     public abstract object FromReflectionType(object value);
   }
 }
\ No newline at end of file

csharp/ProtocolBuffers/GeneratedMessage.cs

@@ -48,8 +48,11 @@ namespace Google.ProtocolBuffers {
       MessageDescriptor descriptor = DescriptorForType;
       foreach (FieldDescriptor field in descriptor.Fields) {
         IFieldAccessor accessor = InternalFieldAccessors[field];
-        if ((field.IsRepeated && accessor.GetRepeatedCount(this) != 0)
-            || accessor.Has(this)) {
+        if (field.IsRepeated) {
+          if (accessor.GetRepeatedCount(this) != 0) {
+            ret[field] = accessor.GetValue(this);
+          }
+        } else if (HasField(field)) {
           ret[field] = accessor.GetValue(this);
         }
       }

csharp/ProtocolBuffers/GeneratedRepeatException.cs

@@ -8,11 +8,11 @@ namespace Google.ProtocolBuffers {
   /// 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) {
+    private GeneratedRepeatExtension(FieldDescriptor field) : base(field, typeof(TExtensionElement)) {
     }
 
     public static GeneratedExtensionBase<TContainer, IList<TExtensionElement>> CreateInstance(FieldDescriptor descriptor) {
-      if (descriptor.IsRepeated) {
+      if (!descriptor.IsRepeated) {
         throw new ArgumentException("Must call GeneratedRepeatExtension.CreateInstance() for repeated types.");
       }
       return new GeneratedRepeatExtension<TContainer, TExtensionElement>(descriptor);

csharp/ProtocolBuffers/GeneratedSingleExtension.cs

@@ -9,7 +9,7 @@ namespace Google.ProtocolBuffers {
   public class GeneratedSingleExtension<TContainer, TExtension> : GeneratedExtensionBase<TContainer, TExtension>    
       where TContainer : IMessage<TContainer> {
 
-    internal GeneratedSingleExtension(FieldDescriptor descriptor) : base(descriptor) {
+    internal GeneratedSingleExtension(FieldDescriptor descriptor) : base(descriptor, typeof(TExtension)) {
     }
 
     public static GeneratedSingleExtension<TContainer, TExtension> CreateInstance(FieldDescriptor descriptor) {

csharp/ProtocolBuffers/IBuilder.cs

@@ -50,6 +50,18 @@ namespace Google.ProtocolBuffers {
     /// <returns></returns>
     object this[FieldDescriptor field] { get; set; }
 
+    /// <summary>
+    /// Only present in the nongeneric interface - useful for tests, but
+    /// not as much in real life.
+    /// </summary>
+    IBuilder SetField(FieldDescriptor field, object value);
+
+    /// <summary>
+    /// Only present in the nongeneric interface - useful for tests, but
+    /// not as much in real life.
+    /// </summary>
+    IBuilder SetRepeatedField(FieldDescriptor field, int index, object value);
+
     /// <summary>
     /// Get the message's type's descriptor.
     /// <see cref="IMessage{T}.DescriptorForType"/>

csharp/ProtocolBuffers/ProtocolBuffers.csproj

@@ -68,6 +68,7 @@
     <Compile Include="Descriptors\PackageDescriptor.cs" />
     <Compile Include="Descriptors\ServiceDescriptor.cs" />
     <Compile Include="DynamicMessage.cs" />
+    <Compile Include="ExtendableBuilder.cs" />
     <Compile Include="ExtendableMessage.cs" />
     <Compile Include="ExtensionInfo.cs" />
     <Compile Include="ExtensionRegistry.cs" />

csharp/ProtocolBuffers/TextGenerator.cs

@@ -70,6 +70,9 @@ namespace Google.ProtocolBuffers {
     }
 
     private void Write(string data) {
+      if (data.Length == 0) {
+        return;
+      }
       if (atStartOfLine) {
         atStartOfLine = false;
         writer.Write(indent);