Quasar/Client/Core/ProtoBuf/BufferExtension.cs

using System;
using System.IO;

namespace ProtoBuf
{
    /// <summary>
    /// Provides a simple buffer-based implementation of an <see cref="IExtension">extension</see> object.
    /// </summary>
    public sealed class BufferExtension : IExtension
    {
        private byte[] buffer;

        int IExtension.GetLength()
        {
            return buffer == null ? 0 : buffer.Length;
        }

        Stream IExtension.BeginAppend()
        {
            return new MemoryStream();
        }

        void IExtension.EndAppend(Stream stream, bool commit)
        {
            using (stream)
            {
                int len;
                if (commit && (len = (int) stream.Length) > 0)
                {
                    using (MemoryStream ms = (MemoryStream) stream)
                    {
                        if (buffer == null)
                        {
                            // allocate new buffer
                            buffer = ms.ToArray();
                        }
                        else
                        {
                            // resize and copy the data
                            // note: Array.Resize not available on CF
                            int offset = buffer.Length;
                            byte[] tmp = new byte[offset + len];
                            Helpers.BlockCopy(buffer, 0, tmp, 0, offset);

#if PORTABLE || WINRT // no GetBuffer() - fine, we'll use Read instead
                        int bytesRead;
                        long oldPos = ms.Position;
                        ms.Position = 0;
                        while (len > 0 && (bytesRead = ms.Read(tmp, offset, len)) > 0)
                        {
                            len -= bytesRead;
                            offset += bytesRead;
                        }
                        if(len != 0) throw new EndOfStreamException();
                        ms.Position = oldPos;
#else
                            Helpers.BlockCopy(ms.GetBuffer(), 0, tmp, offset, len);
#endif
                            buffer = tmp;
                        }
                    }
                }
            }
        }

        Stream IExtension.BeginQuery()
        {
            return buffer == null ? Stream.Null : new MemoryStream(buffer);
        }

        void IExtension.EndQuery(Stream stream)
        {
            // Clean up
            if (stream != null)
            {
                stream.Dispose();
            }
        }
    }
}