#region Copyright notice and license
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// http://github.com/jskeet/dotnet-protobufs/
// Original C++/Java/Python code:
// http://code.google.com/p/protobuf/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#endregion
using System.Collections.Generic;
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 partial class ExtensionRegistry
{
private readonly IDictionary<ExtensionIntPair, IGeneratedExtensionLite> extensionsByNumber;
private readonly bool readOnly;
private ExtensionRegistry(IDictionary<ExtensionIntPair, IGeneratedExtensionLite> extensionsByNumber,
bool readOnly)
{
this.extensionsByNumber = extensionsByNumber;
this.readOnly = readOnly;
}
#if LITE
private static readonly ExtensionRegistry empty = new ExtensionRegistry(
new Dictionary<ExtensionIntPair, IGeneratedExtensionLite>(),
true);
/// <summary>
/// Construct a new, empty instance.
/// </summary>
public static ExtensionRegistry CreateInstance()
{
return new ExtensionRegistry(
new Dictionary<ExtensionIntPair, IGeneratedExtensionLite>(), false);
}
public ExtensionRegistry AsReadOnly()
{
return new ExtensionRegistry(extensionsByNumber, true);
}
#endif
/// <summary>
/// Get the unmodifiable singleton empty instance.
/// </summary>
public static ExtensionRegistry Empty
{
get { return empty; }
}
/// <summary>
/// Finds an extension by containing type and field number.
/// A null reference is returned if the extension can't be found.
/// </summary>
public IGeneratedExtensionLite this[IMessageLite containingType, int fieldNumber]
{
get
{
IGeneratedExtensionLite ret;
extensionsByNumber.TryGetValue(new ExtensionIntPair(containingType, fieldNumber), out ret);
return ret;
}
}
/// <summary>
/// Add an extension from a generated file to the registry.
/// </summary>
public void Add(IGeneratedExtensionLite extension)
{
if (readOnly)
{
throw new InvalidOperationException("Cannot add entries to a read-only extension registry");
}
extensionsByNumber.Add(
new ExtensionIntPair(extension.ContainingType, extension.Number),
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 ExtensionIntPair : IEquatable<ExtensionIntPair>
{
private readonly object msgType;
private readonly int number;
internal ExtensionIntPair(object msgType, int number)
{
this.msgType = msgType;
this.number = number;
}
public override int GetHashCode()
{
return msgType.GetHashCode()*((1 << 16) - 1) + number;
}
public override bool Equals(object obj)
{
if (!(obj is ExtensionIntPair))
{
return false;
}
return Equals((ExtensionIntPair) obj);
}
public bool Equals(ExtensionIntPair other)
{
return msgType.Equals(other.msgType) && number == other.number;
}
}
}
}
