Revamp to reflection.

Changes in brief:
1. Descriptor is now the entry point for all reflection.
2. IReflectedMessage has gone; there's now a Descriptor property in IMessage, which is explicitly implemented (due to the static property).
3. FieldAccessorTable has gone away
4. IFieldAccessor and OneofFieldAccessor still exist; we *could* put the functionality straight into FieldDescriptor and OneofDescriptor... I'm unsure about that.
5. There's a temporary property MessageDescriptor.FieldAccessorsByFieldNumber to make the test changes small - we probably want this to go away
6. Discovery for delegates is now via attributes applied to properties and the Clear method of a oneof

I'm happy with 1-3.
4 I'm unsure about - feedback welcome.
5 will go away
6 I'm unsure about, both in design and implementation. Should we have a ProtobufMessageAttribute too? Should we find all the relevant attributes in MessageDescriptor and pass them down, to avoid an O(N^2) scenario?

Generated code changes coming in the next commit.

1 files changed, 24 insertions, 23 deletions

diff --git a/csharp/src/Google.Protobuf.Test/GeneratedMessageTest.cs b/csharp/src/Google.Protobuf.Test/GeneratedMessageTest.cs
index acb20b15..180976d1 100644
--- a/csharp/src/Google.Protobuf.Test/GeneratedMessageTest.cs
+++ b/csharp/src/Google.Protobuf.Test/GeneratedMessageTest.cs
@@ -604,7 +604,7 @@ namespace Google.Protobuf
         public void Reflection_GetValue()

         {

             var message = SampleMessages.CreateFullTestAllTypes();

-            var fields = ((IReflectedMessage) message).Fields;

+            var fields = TestAllTypes.Descriptor.FieldAccessorsByFieldNumber;

             Assert.AreEqual(message.SingleBool, fields[TestAllTypes.SingleBoolFieldNumber].GetValue(message));

             Assert.AreEqual(message.SingleBytes, fields[TestAllTypes.SingleBytesFieldNumber].GetValue(message));

             Assert.AreEqual(message.SingleDouble, fields[TestAllTypes.SingleDoubleFieldNumber].GetValue(message));

@@ -639,7 +639,7 @@ namespace Google.Protobuf
 

             // Just a single map field, for the same reason

             var mapMessage = new TestMap { MapStringString = { { "key1", "value1" }, { "key2", "value2" } } };

-            fields = ((IReflectedMessage) mapMessage).Fields;

+            fields = TestMap.Descriptor.FieldAccessorsByFieldNumber;

             var dictionary = (IDictionary) fields[TestMap.MapStringStringFieldNumber].GetValue(mapMessage);

             Assert.AreEqual(mapMessage.MapStringString, dictionary);

             Assert.AreEqual("value1", dictionary["key1"]);

@@ -648,8 +648,8 @@ namespace Google.Protobuf
         [Test]

         public void Reflection_Clear()

         {

-            IReflectedMessage message = SampleMessages.CreateFullTestAllTypes();

-            var fields = message.Fields;

+            var message = SampleMessages.CreateFullTestAllTypes();

+            var fields = TestAllTypes.Descriptor.FieldAccessorsByFieldNumber;

             fields[TestAllTypes.SingleBoolFieldNumber].Clear(message);

             fields[TestAllTypes.SingleInt32FieldNumber].Clear(message);

             fields[TestAllTypes.SingleStringFieldNumber].Clear(message);

@@ -673,7 +673,7 @@ namespace Google.Protobuf
 

             // Separately, maps.

             var mapMessage = new TestMap { MapStringString = { { "key1", "value1" }, { "key2", "value2" } } };

-            fields = ((IReflectedMessage) mapMessage).Fields;

+            fields = TestMap.Descriptor.FieldAccessorsByFieldNumber;

             fields[TestMap.MapStringStringFieldNumber].Clear(mapMessage);

             Assert.AreEqual(0, mapMessage.MapStringString.Count);

         }

@@ -682,8 +682,8 @@ namespace Google.Protobuf
         public void Reflection_SetValue_SingleFields()

         {

             // Just a sample (primitives, messages, enums, strings, byte strings)

-            IReflectedMessage message = SampleMessages.CreateFullTestAllTypes();

-            var fields = message.Fields;

+            var message = SampleMessages.CreateFullTestAllTypes();

+            var fields = TestAllTypes.Descriptor.FieldAccessorsByFieldNumber;

             fields[TestAllTypes.SingleBoolFieldNumber].SetValue(message, false);

             fields[TestAllTypes.SingleInt32FieldNumber].SetValue(message, 500);

             fields[TestAllTypes.SingleStringFieldNumber].SetValue(message, "It's a string");

@@ -709,51 +709,52 @@ namespace Google.Protobuf
         [Test]

         public void Reflection_SetValue_SingleFields_WrongType()

         {

-            IReflectedMessage message = SampleMessages.CreateFullTestAllTypes();

-            var fields = message.Fields;

+            IMessage message = SampleMessages.CreateFullTestAllTypes();

+            var fields = message.Descriptor.FieldAccessorsByFieldNumber;

             Assert.Throws<InvalidCastException>(() => fields[TestAllTypes.SingleBoolFieldNumber].SetValue(message, "This isn't a bool"));

         }

 

         [Test]

         public void Reflection_SetValue_MapFields()

         {

-            IReflectedMessage message = new TestMap();

-            var fields = message.Fields;

+            IMessage message = new TestMap();

+            var fields = message.Descriptor.FieldAccessorsByFieldNumber;

             Assert.Throws<InvalidOperationException>(() => fields[TestMap.MapStringStringFieldNumber].SetValue(message, new Dictionary<string, string>()));

         }

 

         [Test]

         public void Reflection_SetValue_RepeatedFields()

         {

-            IReflectedMessage message = SampleMessages.CreateFullTestAllTypes();

-            var fields = message.Fields;

+            IMessage message = SampleMessages.CreateFullTestAllTypes();

+            var fields = message.Descriptor.FieldAccessorsByFieldNumber;

             Assert.Throws<InvalidOperationException>(() => fields[TestAllTypes.RepeatedDoubleFieldNumber].SetValue(message, new double[10]));

         }

 

         [Test]

         public void Reflection_GetValue_IncorrectType()

         {

-            IReflectedMessage message = SampleMessages.CreateFullTestAllTypes();

-            Assert.Throws<InvalidCastException>(() => message.Fields[TestAllTypes.SingleBoolFieldNumber].GetValue(new TestMap()));

+            IMessage message = SampleMessages.CreateFullTestAllTypes();

+            var fields = message.Descriptor.FieldAccessorsByFieldNumber;

+            Assert.Throws<InvalidCastException>(() => fields[TestAllTypes.SingleBoolFieldNumber].GetValue(new TestMap()));

         }

 

         [Test]

         public void Reflection_Oneof()

         {

             var message = new TestAllTypes();

-            var fields = ((IReflectedMessage) message).Fields;

-            Assert.AreEqual(1, fields.Oneofs.Count);

-            var oneof = fields.Oneofs[0];

-            Assert.AreEqual("oneof_field", oneof.Descriptor.Name);

-            Assert.IsNull(oneof.GetCaseFieldDescriptor(message));

+            var descriptor = TestAllTypes.Descriptor;

+            Assert.AreEqual(1, descriptor.Oneofs.Count);

+            var oneof = descriptor.Oneofs[0];

+            Assert.AreEqual("oneof_field", oneof.Name);

+            Assert.IsNull(oneof.Accessor.GetCaseFieldDescriptor(message));

 

             message.OneofString = "foo";

-            Assert.AreSame(fields[TestAllTypes.OneofStringFieldNumber].Descriptor, oneof.GetCaseFieldDescriptor(message));

+            Assert.AreSame(descriptor.FieldAccessorsByFieldNumber[TestAllTypes.OneofStringFieldNumber].Descriptor, oneof.Accessor.GetCaseFieldDescriptor(message));

 

             message.OneofUint32 = 10;

-            Assert.AreSame(fields[TestAllTypes.OneofUint32FieldNumber].Descriptor, oneof.GetCaseFieldDescriptor(message));

+            Assert.AreSame(descriptor.FieldAccessorsByFieldNumber[TestAllTypes.OneofUint32FieldNumber].Descriptor, oneof.Accessor.GetCaseFieldDescriptor(message));

 

-            oneof.Clear(message);

+            oneof.Accessor.Clear(message);

             Assert.AreEqual(TestAllTypes.OneofFieldOneofCase.None, message.OneofFieldCase);

         }

     }