1 files changed, 50 insertions, 2 deletions
diff --git a/csharp/ProtocolBuffers/FieldAccess/FieldAccessorTable.cs b/csharp/ProtocolBuffers/FieldAccess/FieldAccessorTable.cs
index 7fec437f..231b974c 100644
--- a/csharp/ProtocolBuffers/FieldAccess/FieldAccessorTable.cs
+++ b/csharp/ProtocolBuffers/FieldAccess/FieldAccessorTable.cs
@@ -2,20 +2,68 @@
 using Google.ProtocolBuffers.Descriptors;
 
 namespace Google.ProtocolBuffers.FieldAccess {
+  /// <summary>
+  /// Provides access to fields in generated messages via reflection.
+  /// This type is public to allow it to be used by generated messages, which
+  /// create appropriate instances in the .proto file description class.
+  /// TODO(jonskeet): See if we can hide it somewhere...
+  /// </summary>
   public class FieldAccessorTable {
 
+    readonly IFieldAccessor[] accessors;
+
     readonly MessageDescriptor descriptor;
 
     public MessageDescriptor Descriptor { 
       get { return descriptor; }
     }
 
-    public FieldAccessorTable(MessageDescriptor descriptor, String[] pascalCaseFieldNames, Type messageType, Type builderType) {
+   /// <summary>
+    /// Constructs a FieldAccessorTable for a particular message class.
+    /// Only one FieldAccessorTable should be constructed per class.
+    /// </summary>
+    /// <param name="descriptor">The type's descriptor</param>
+    /// <param name="propertyNames">The Pascal-case names of all the field-based properties in the message.</param>
+    /// <param name="messageType">The .NET type representing the message</param>
+    /// <param name="builderType">The .NET type representing the message's builder type</param>
+    public FieldAccessorTable(MessageDescriptor descriptor, String[] propertyNames, Type messageType, Type builderType) {
       this.descriptor = descriptor;
+      accessors = new IFieldAccessor[descriptor.Fields.Count];
+      for (int i=0; i < accessors.Length; i++) {
+        accessors[i] = CreateAccessor(descriptor.Fields[i], propertyNames[i], messageType, builderType);
+      }
+    }
+
+     /// <summary>
+     /// Creates an accessor for a single field
+     /// </summary>   
+    private static IFieldAccessor CreateAccessor(FieldDescriptor field, string name, Type messageType, Type builderType) {
+      if (field.IsRepeated) {
+        switch (field.MappedType) {
+          case MappedType.Message: return new RepeatedMessageAccessor(name, messageType, builderType);
+          case MappedType.Enum: return new RepeatedEnumAccessor(field, name, messageType, builderType);
+          default: return new RepeatedPrimitiveAccessor(name, messageType, builderType);
+        }
+      } else {
+        switch (field.MappedType) {
+          case MappedType.Message: return new SingleMessageAccessor(name, messageType, builderType);
+          case MappedType.Enum: return new SingleEnumAccessor(field, name, messageType, builderType);
+          default: return new SinglePrimitiveAccessor(name, messageType, builderType);
+        }
+      }
     }
 
     internal IFieldAccessor this[FieldDescriptor field] {
-      get { return null; }
+      get {
+        if (field.ContainingType != descriptor) {
+          throw new ArgumentException("FieldDescriptor does not match message type.");
+        } else if (field.IsExtension) {
+          // If this type had extensions, it would subclass ExtendableMessage,
+          // which overrides the reflection interface to handle extensions.
+          throw new ArgumentException("This type does not have extensions.");
+        }
+        return accessors[field.Index];
+      }
     }
   }
 }