Field accessor implementations complete (hopefully)

1 files changed, 52 insertions, 0 deletions

diff --git a/csharp/ProtocolBuffers/FieldAccess/SingleMessageAccessor.cs b/csharp/ProtocolBuffers/FieldAccess/SingleMessageAccessor.cs
new file mode 100644
index 00000000..c9647b07
--- /dev/null
+++ b/csharp/ProtocolBuffers/FieldAccess/SingleMessageAccessor.cs
@@ -0,0 +1,52 @@
+using System;
+using System.Reflection;
+using Google.ProtocolBuffers.Descriptors;
+
+namespace Google.ProtocolBuffers.FieldAccess {
+  /// <summary>
+  /// Accessor for fields representing a non-repeated message value.
+  /// </summary>
+  internal sealed class SingleMessageAccessor : SinglePrimitiveAccessor {
+
+    /// <summary>
+    /// The static method to create a builder for the property type. For example,
+    /// in a message type "Foo", a field called "bar" might be of type "Baz". This
+    /// method is Baz.CreateBuilder.
+    /// </summary>
+    private readonly MethodInfo createBuilderMethod;
+
+
+    internal SingleMessageAccessor(string name, Type messageType, Type builderType) 
+        : base(name, messageType, builderType) {
+      
+      createBuilderMethod = ClrType.GetMethod("CreateBuilder", BindingFlags.Public | BindingFlags.Static);
+      if (createBuilderMethod == null) {
+        throw new ArgumentException("No public static CreateBuilder method declared in " + ClrType.Name);
+      }
+    }
+
+    /// <summary>
+    /// Creates a message of the appropriate CLR type from the given value,
+    /// which may already be of the right type or may be a dynamic message.
+    /// </summary>
+    private object CoerceType(object value) {
+
+      // If it's already of the right type, we're done
+      if (ClrType.IsInstanceOfType(value)) {
+        return value;
+      }
+      
+      // No... so let's create a builder of the right type, and merge the value in.
+      IMessage message = (IMessage) value;
+      return CreateBuilder().MergeFrom(message).Build();
+    }
+
+    public override void SetValue(IBuilder builder, object value) {
+      base.SetValue(builder, CoerceType(value));
+    }
+
+    public override IBuilder CreateBuilder() {
+      return (IBuilder) createBuilderMethod.Invoke(null, null);
+    }
+  }
+}
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