First cut at new layout
diff --git a/src/ProtocolBuffers/ExtensionRegistry.cs b/src/ProtocolBuffers/ExtensionRegistry.cs
new file mode 100644
index 0000000..dec7573
--- /dev/null
+++ b/src/ProtocolBuffers/ExtensionRegistry.cs
@@ -0,0 +1,226 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.
+// http://code.google.com/p/protobuf/
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// 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 System.Collections.Generic;
+using Google.ProtocolBuffers.Descriptors;
+using System;
+
+namespace Google.ProtocolBuffers {
+ /// <summary>
+ /// A table of known extensions, searchable by name or field number. When
+ /// parsing a protocol message that might have extensions, you must provide
+ /// an <see cref="ExtensionRegistry"/> in which you have registered any extensions
+ /// that you want to be able to parse. Otherwise, those extensions will just
+ /// be treated like unknown fields.
+ /// </summary>
+ /// <example>
+ /// For example, if you had the <c>.proto</c> file:
+ /// <code>
+ /// option java_class = "MyProto";
+ ///
+ /// message Foo {
+ /// extensions 1000 to max;
+ /// }
+ ///
+ /// extend Foo {
+ /// optional int32 bar;
+ /// }
+ /// </code>
+ ///
+ /// Then you might write code like:
+ ///
+ /// <code>
+ /// ExtensionRegistry registry = ExtensionRegistry.CreateInstance();
+ /// registry.Add(MyProto.Bar);
+ /// MyProto.Foo message = MyProto.Foo.ParseFrom(input, registry);
+ /// </code>
+ /// </example>
+ ///
+ /// <remarks>
+ /// <para>You might wonder why this is necessary. Two alternatives might come to
+ /// mind. First, you might imagine a system where generated extensions are
+ /// automatically registered when their containing classes are loaded. This
+ /// is a popular technique, but is bad design; among other things, it creates a
+ /// situation where behavior can change depending on what classes happen to be
+ /// loaded. It also introduces a security vulnerability, because an
+ /// unprivileged class could cause its code to be called unexpectedly from a
+ /// privileged class by registering itself as an extension of the right type.
+ /// </para>
+ /// <para>Another option you might consider is lazy parsing: do not parse an
+ /// extension until it is first requested, at which point the caller must
+ /// provide a type to use. This introduces a different set of problems. First,
+ /// it would require a mutex lock any time an extension was accessed, which
+ /// would be slow. Second, corrupt data would not be detected until first
+ /// access, at which point it would be much harder to deal with it. Third, it
+ /// could violate the expectation that message objects are immutable, since the
+ /// type provided could be any arbitrary message class. An unprivileged user
+ /// could take advantage of this to inject a mutable object into a message
+ /// belonging to privileged code and create mischief.</para>
+ /// </remarks>
+ public sealed class ExtensionRegistry {
+
+ private static readonly ExtensionRegistry empty = new ExtensionRegistry(
+ new Dictionary<string, ExtensionInfo>(),
+ new Dictionary<DescriptorIntPair, ExtensionInfo>(),
+ true);
+
+ private readonly IDictionary<string, ExtensionInfo> extensionsByName;
+ private readonly IDictionary<DescriptorIntPair, ExtensionInfo> extensionsByNumber;
+ private readonly bool readOnly;
+
+ private ExtensionRegistry(IDictionary<String, ExtensionInfo> extensionsByName,
+ IDictionary<DescriptorIntPair, ExtensionInfo> extensionsByNumber,
+ bool readOnly) {
+ this.extensionsByName = extensionsByName;
+ this.extensionsByNumber = extensionsByNumber;
+ this.readOnly = readOnly;
+ }
+
+ /// <summary>
+ /// Construct a new, empty instance.
+ /// </summary>
+ public static ExtensionRegistry CreateInstance() {
+ return new ExtensionRegistry(new Dictionary<string, ExtensionInfo>(),
+ new Dictionary<DescriptorIntPair, ExtensionInfo>(), false);
+ }
+
+ /// <summary>
+ /// Get the unmodifiable singleton empty instance.
+ /// </summary>
+ public static ExtensionRegistry Empty {
+ get { return empty; }
+ }
+
+ public ExtensionRegistry AsReadOnly() {
+ return new ExtensionRegistry(extensionsByName, extensionsByNumber, true);
+ }
+
+ /// <summary>
+ /// Finds an extension by fully-qualified field name, in the
+ /// proto namespace, i.e. result.Descriptor.FullName will match
+ /// <paramref name="fullName"/> if a match is found. A null
+ /// reference is returned if the extension can't be found.
+ /// </summary>
+ public ExtensionInfo this[string fullName] {
+ get {
+ ExtensionInfo ret;
+ extensionsByName.TryGetValue(fullName, out ret);
+ return ret;
+ }
+ }
+
+ /// <summary>
+ /// Finds an extension by containing type and field number.
+ /// A null reference is returned if the extension can't be found.
+ /// </summary>
+ public ExtensionInfo this[MessageDescriptor containingType, int fieldNumber] {
+ get {
+ ExtensionInfo ret;
+ extensionsByNumber.TryGetValue(new DescriptorIntPair(containingType, fieldNumber), out ret);
+ return ret;
+ }
+ }
+
+ /// <summary>
+ /// Add an extension from a generated file to the registry.
+ /// </summary>
+ public void Add<TExtension> (GeneratedExtensionBase<TExtension> extension) {
+ if (extension.Descriptor.MappedType == MappedType.Message) {
+ Add(new ExtensionInfo(extension.Descriptor, extension.MessageDefaultInstance));
+ } else {
+ Add(new ExtensionInfo(extension.Descriptor, null));
+ }
+ }
+
+ /// <summary>
+ /// Adds a non-message-type extension to the registry by descriptor.
+ /// </summary>
+ /// <param name="type"></param>
+ public void Add(FieldDescriptor type) {
+ if (type.MappedType == MappedType.Message) {
+ throw new ArgumentException("ExtensionRegistry.Add() must be provided a default instance "
+ + "when adding an embedded message extension.");
+ }
+ Add(new ExtensionInfo(type, null));
+ }
+
+ /// <summary>
+ /// Adds a message-type-extension to the registry by descriptor.
+ /// </summary>
+ /// <param name="type"></param>
+ /// <param name="defaultInstance"></param>
+ public void Add(FieldDescriptor type, IMessage defaultInstance) {
+ if (type.MappedType != MappedType.Message) {
+ throw new ArgumentException("ExtensionRegistry.Add() provided a default instance for a "
+ + "non-message extension.");
+ }
+ Add(new ExtensionInfo(type, defaultInstance));
+ }
+
+ private void Add(ExtensionInfo extension) {
+ if (readOnly) {
+ throw new InvalidOperationException("Cannot add entries to a read-only extension registry");
+ }
+ if (!extension.Descriptor.IsExtension) {
+ throw new ArgumentException("ExtensionRegistry.add() was given a FieldDescriptor for a "
+ + "regular (non-extension) field.");
+ }
+
+ extensionsByName[extension.Descriptor.FullName] = extension;
+ extensionsByNumber[new DescriptorIntPair(extension.Descriptor.ContainingType,
+ extension.Descriptor.FieldNumber)] = extension;
+
+ FieldDescriptor field = extension.Descriptor;
+ if (field.ContainingType.Options.MessageSetWireFormat
+ && field.FieldType == FieldType.Message
+ && field.IsOptional
+ && field.ExtensionScope == field.MessageType) {
+ // This is an extension of a MessageSet type defined within the extension
+ // type's own scope. For backwards-compatibility, allow it to be looked
+ // up by type name.
+ extensionsByName[field.MessageType.FullName] = extension;
+ }
+ }
+
+ /// <summary>
+ /// Nested type just used to represent a pair of MessageDescriptor and int, as
+ /// the key into the "by number" map.
+ /// </summary>
+ private struct DescriptorIntPair : IEquatable<DescriptorIntPair> {
+ readonly MessageDescriptor descriptor;
+ readonly int number;
+
+ internal DescriptorIntPair(MessageDescriptor descriptor, int number) {
+ this.descriptor = descriptor;
+ this.number = number;
+ }
+
+ public override int GetHashCode() {
+ return descriptor.GetHashCode() * ((1 << 16) - 1) + number;
+ }
+
+ public override bool Equals(object obj) {
+ if (!(obj is DescriptorIntPair)) {
+ return false;
+ }
+ return Equals((DescriptorIntPair)obj);
+ }
+
+ public bool Equals(DescriptorIntPair other) {
+ return descriptor == other.descriptor && number == other.number;
+ }
+ }
+ }
+}