QPID-128 Initial import of the C# sources.

git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@479211 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 140 insertions, 0 deletions

diff --git a/dotnet/Qpid.Codec/CumulativeProtocolDecoder.cs b/dotnet/Qpid.Codec/CumulativeProtocolDecoder.cs
new file mode 100644
index 0000000000..70b4940c7b
--- /dev/null
+++ b/dotnet/Qpid.Codec/CumulativeProtocolDecoder.cs
@@ -0,0 +1,140 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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;
+using Qpid.Buffer;
+
+namespace Qpid.Codec
+{
+    public abstract class CumulativeProtocolDecoder : IProtocolDecoder
+    {
+        ByteBuffer _remaining;
+
+        /// <summary>
+        /// Creates a new instance with the 65535 bytes initial capacity of
+        /// cumulative buffer.
+        /// Note that capacity is currently fixed as the .NET ByteBuffers does not implement auto-expansion.
+        /// </summary>
+        protected CumulativeProtocolDecoder()
+        {
+            // Needs to be as large as the largest frame to be decoded.
+            _remaining = ByteBuffer.Allocate(65535); // FIXME: Probably should not be fixed.
+        }
+
+        /// <summary>
+        /// Cumulates content of <tt>in</tt> into internal buffer and forwards
+        /// decoding request to {@link #doDecode(IoSession, ByteBuffer, ProtocolDecoderOutput)}.
+        /// <tt>doDecode()</tt> is invoked repeatedly until it returns <tt>false</tt>
+        /// and the cumulative buffer is compacted after decoding ends.
+        /// </summary>
+        /// <exception cref="Exception">
+        /// if your <tt>doDecode()</tt> returned <tt>true</tt> not consuming the cumulative buffer.
+        /// </exception>
+        public void Decode(ByteBuffer input, IProtocolDecoderOutput output)
+        {
+            if (_remaining.Position != 0) // If there were remaining undecoded bytes
+            {
+                DecodeRemainingAndInput(input, output);
+            }
+            else
+            {
+                DecodeInput(input, output);
+            }
+        }
+
+        private void DecodeInput(ByteBuffer input, IProtocolDecoderOutput output)
+        {
+            // Just decode the input buffer and remember any remaining undecoded bytes.
+            try
+            {
+                DecodeAll(input, output);
+            }
+            finally
+            {
+                if (input.HasRemaining())
+                {
+                    _remaining.Put(input);
+                }
+            }
+        }
+
+        private void DecodeRemainingAndInput(ByteBuffer input, IProtocolDecoderOutput output)
+        {
+            // Concatenate input buffer with left-over bytes.
+            _remaining.Put(input);
+            _remaining.Flip();
+
+            try
+            {
+                DecodeAll(_remaining, output);
+            }
+            finally
+            {
+                _remaining.Compact();
+            }
+        }
+
+        private void DecodeAll(ByteBuffer buf, IProtocolDecoderOutput output)
+        {
+            for (;;)
+            {
+                int oldPos = buf.Position;                    
+                bool decoded = DoDecode(buf, output);
+                if (decoded)
+                {                        
+                    if (buf.Position == oldPos)
+                    {
+                        throw new Exception(
+                            "doDecode() can't return true when buffer is not consumed.");
+                    }
+
+                    if (!buf.HasRemaining())
+                    {
+                        break;
+                    }
+                }
+                else
+                {
+                    break;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Implement this method to consume the specified cumulative buffer and
+        /// decode its content into message(s). 
+        /// </summary>
+        /// <param name="input">the cumulative buffer</param>
+        /// <param name="output">decoder output</param>
+        /// <returns>
+        /// <tt>true</tt> if and only if there's more to decode in the buffer
+        /// and you want to have <tt>doDecode</tt> method invoked again.
+        /// Return <tt>false</tt> if remaining data is not enough to decode,
+        /// then this method will be invoked again when more data is cumulated.
+        /// </returns>
+        /// <exception cref="Exception">If cannot decode</exception>
+        protected abstract bool DoDecode(ByteBuffer input, IProtocolDecoderOutput output);
+
+        public void Dispose()
+        {
+            _remaining = null;
+        }
+    }
+}