78 lines
2.3 KiB
C#
78 lines
2.3 KiB
C#
using System;
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using System.IO;
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namespace ProtoBuf
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{
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/// <summary>
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/// Provides a simple buffer-based implementation of an <see cref="IExtension">extension</see> object.
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/// </summary>
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public sealed class BufferExtension : IExtension, IExtensionResettable
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{
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private byte[] buffer;
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void IExtensionResettable.Reset()
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{
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buffer = null;
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}
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int IExtension.GetLength()
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{
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return buffer == null ? 0 : buffer.Length;
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}
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Stream IExtension.BeginAppend()
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{
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return new MemoryStream();
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}
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void IExtension.EndAppend(Stream stream, bool commit)
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{
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using (stream)
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{
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int len;
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if (commit && (len = (int)stream.Length) > 0)
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{
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MemoryStream ms = (MemoryStream)stream;
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if (buffer == null)
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{ // allocate new buffer
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buffer = ms.ToArray();
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}
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else
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{ // resize and copy the data
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// note: Array.Resize not available on CF
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int offset = buffer.Length;
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byte[] tmp = new byte[offset + len];
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Buffer.BlockCopy(buffer, 0, tmp, 0, offset);
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#if PORTABLE // no GetBuffer() - fine, we'll use Read instead
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int bytesRead;
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long oldPos = ms.Position;
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ms.Position = 0;
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while (len > 0 && (bytesRead = ms.Read(tmp, offset, len)) > 0)
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{
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len -= bytesRead;
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offset += bytesRead;
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}
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if(len != 0) throw new EndOfStreamException();
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ms.Position = oldPos;
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#else
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Buffer.BlockCopy(Helpers.GetBuffer(ms), 0, tmp, offset, len);
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#endif
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buffer = tmp;
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}
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}
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}
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}
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Stream IExtension.BeginQuery()
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{
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return buffer == null ? Stream.Null : new MemoryStream(buffer);
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}
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void IExtension.EndQuery(Stream stream)
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{
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using (stream) { } // just clean up
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}
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}
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} |