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author | Jan Tattermusch <jtattermusch@users.noreply.github.com> | 2015-04-17 14:15:52 -0700 |
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committer | Jan Tattermusch <jtattermusch@users.noreply.github.com> | 2015-04-17 14:15:52 -0700 |
commit | 01c8c35ca3d3424a9473dd22ea2456933b3e8d36 (patch) | |
tree | de582cb9ef3e449f24015dec09f80e998806b26a /csharp/src/ProtocolBuffers/MessageStreamIterator.cs | |
parent | 813d6d652d8091e9365bfbd01efb5f2ee8bdfbce (diff) | |
parent | 1eab56aee8dddcb656db67d9fb87a8cc6a2ac112 (diff) | |
download | protobuf-01c8c35ca3d3424a9473dd22ea2456933b3e8d36.tar.gz protobuf-01c8c35ca3d3424a9473dd22ea2456933b3e8d36.tar.bz2 protobuf-01c8c35ca3d3424a9473dd22ea2456933b3e8d36.zip |
Merge pull request #2 from jtattermusch/csharp_protobuf_imported
Pulling protobuf-csharp-port into csharp/ directory
Diffstat (limited to 'csharp/src/ProtocolBuffers/MessageStreamIterator.cs')
-rw-r--r-- | csharp/src/ProtocolBuffers/MessageStreamIterator.cs | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/csharp/src/ProtocolBuffers/MessageStreamIterator.cs b/csharp/src/ProtocolBuffers/MessageStreamIterator.cs new file mode 100644 index 00000000..32d697ca --- /dev/null +++ b/csharp/src/ProtocolBuffers/MessageStreamIterator.cs @@ -0,0 +1,170 @@ +#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;
+using System.Collections;
+using System.Collections.Generic;
+using System.IO;
+
+namespace Google.ProtocolBuffers
+{
+ /// <summary>
+ /// Iterates over data created using a <see cref="MessageStreamWriter{T}" />.
+ /// Unlike MessageStreamWriter, this class is not usually constructed directly with
+ /// a stream; instead it is provided with a way of opening a stream when iteration
+ /// is started. The stream is closed when the iteration is completed or the enumerator
+ /// is disposed. (This occurs naturally when using <c>foreach</c>.)
+ /// </summary>
+ public class MessageStreamIterator<TMessage> : IEnumerable<TMessage>
+ where TMessage : IMessage<TMessage>
+ {
+ private readonly StreamProvider streamProvider;
+ private readonly ExtensionRegistry extensionRegistry;
+ private readonly int sizeLimit;
+
+ /// <summary>
+ /// The default instance of TMessage type used to construct builders while reading
+ /// </summary>
+ private static readonly TMessage defaultMessageInstance = CreateDefaultInstance();
+ /// <summary>
+ /// Any exception (within reason) thrown in type ctor is caught and rethrown in the constructor.
+ /// This makes life a lot simpler for the caller.
+ /// </summary>
+ private static Exception typeInitializationException;
+
+
+ /// <summary>
+ /// Vastly simplified the reflection to simply obtain the default instance and use it to construct
+ /// the weak builder while simply casting the result. Ideally this class should have required a
+ /// TBuilder type argument with a new() constraint to construct the initial instance thereby the
+ /// reflection could be eliminated.
+ /// </summary>
+ private static TMessage CreateDefaultInstance()
+ {
+ try
+ {
+ return (TMessage)typeof(TMessage)
+ .GetProperty("DefaultInstance", typeof(TMessage), new Type[0])
+ .GetValue(null, null);
+ }
+ catch (Exception e)
+ {
+ typeInitializationException = e;
+ return default(TMessage);
+ }
+ }
+
+ private static readonly uint ExpectedTag = WireFormat.MakeTag(1, WireFormat.WireType.LengthDelimited);
+
+ private MessageStreamIterator(StreamProvider streamProvider, ExtensionRegistry extensionRegistry, int sizeLimit)
+ {
+ if (ReferenceEquals(defaultMessageInstance, null))
+ {
+ throw new System.Reflection.TargetInvocationException(typeInitializationException);
+ }
+ this.streamProvider = streamProvider;
+ this.extensionRegistry = extensionRegistry;
+ this.sizeLimit = sizeLimit;
+ }
+
+ private MessageStreamIterator(StreamProvider streamProvider, ExtensionRegistry extensionRegistry)
+ : this(streamProvider, extensionRegistry, CodedInputStream.DefaultSizeLimit)
+ {
+ }
+
+ /// <summary>
+ /// Creates a new instance which uses the same stream provider as this one,
+ /// but the specified extension registry.
+ /// </summary>
+ public MessageStreamIterator<TMessage> WithExtensionRegistry(ExtensionRegistry newRegistry)
+ {
+ return new MessageStreamIterator<TMessage>(streamProvider, newRegistry, sizeLimit);
+ }
+
+ /// <summary>
+ /// Creates a new instance which uses the same stream provider and extension registry as this one,
+ /// but with the specified size limit. Note that this must be big enough for the largest message
+ /// and the tag and size preceding it.
+ /// </summary>
+ public MessageStreamIterator<TMessage> WithSizeLimit(int newSizeLimit)
+ {
+ return new MessageStreamIterator<TMessage>(streamProvider, extensionRegistry, newSizeLimit);
+ }
+
+#if CLIENTPROFILE
+ public static MessageStreamIterator<TMessage> FromFile(string file)
+ {
+ return new MessageStreamIterator<TMessage>(() => File.OpenRead(file), ExtensionRegistry.Empty);
+ }
+#endif
+
+ public static MessageStreamIterator<TMessage> FromStreamProvider(StreamProvider streamProvider)
+ {
+ return new MessageStreamIterator<TMessage>(streamProvider, ExtensionRegistry.Empty);
+ }
+
+ public IEnumerator<TMessage> GetEnumerator()
+ {
+ using (Stream stream = streamProvider())
+ {
+ CodedInputStream input = CodedInputStream.CreateInstance(stream);
+ input.SetSizeLimit(sizeLimit);
+ uint tag;
+ string name;
+ while (input.ReadTag(out tag, out name))
+ {
+ if ((tag == 0 && name == "item") || (tag == ExpectedTag))
+ {
+ IBuilder builder = defaultMessageInstance.WeakCreateBuilderForType();
+ input.ReadMessage(builder, extensionRegistry);
+ yield return (TMessage)builder.WeakBuild();
+ }
+ else
+ {
+ throw InvalidProtocolBufferException.InvalidMessageStreamTag();
+ }
+
+ input.ResetSizeCounter();
+ }
+ }
+ }
+
+ IEnumerator IEnumerable.GetEnumerator()
+ {
+ return GetEnumerator();
+ }
+ }
+}
\ No newline at end of file |