EightBitStream.cs

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using System.IO;
using System.Text;
 
namespace System.Net.Mime;
 
internal sealed class EightBitStream : DelegatedStream, IEncodableStream
{
    private WriteStateInfoBase _writeState;
 
    private readonly bool _shouldEncodeLeadingDots;
 
    private WriteStateInfoBase WriteState => _writeState ?? (_writeState = new WriteStateInfoBase());
 
    internal EightBitStream(Stream stream)
        : base(stream)
    {
    }
 
    internal EightBitStream(Stream stream, bool shouldEncodeLeadingDots)
        : this(stream)
    {
        _shouldEncodeLeadingDots = shouldEncodeLeadingDots;
    }
 
    public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
    {
        Stream.ValidateBufferArguments(buffer, offset, count);
        if (_shouldEncodeLeadingDots)
        {
            EncodeLines(buffer, offset, count);
            return base.BeginWrite(WriteState.Buffer, 0, WriteState.Length, callback, state);
        }
        return base.BeginWrite(buffer, offset, count, callback, state);
    }
 
    public override void EndWrite(IAsyncResult asyncResult)
    {
        base.EndWrite(asyncResult);
        WriteState.BufferFlushed();
    }
 
    public override void Write(byte[] buffer, int offset, int count)
    {
        Stream.ValidateBufferArguments(buffer, offset, count);
        if (_shouldEncodeLeadingDots)
        {
            EncodeLines(buffer, offset, count);
            base.Write(WriteState.Buffer, 0, WriteState.Length);
            WriteState.BufferFlushed();
        }
        else
        {
            base.Write(buffer, offset, count);
        }
    }
 
    private void EncodeLines(byte[] buffer, int offset, int count)
    {
        for (int i = offset; i < offset + count && i < buffer.Length; i++)
        {
            if (buffer[i] == 13 && i + 1 < offset + count && buffer[i + 1] == 10)
            {
                WriteState.AppendCRLF(includeSpace: false);
                i++;
            }
            else if (WriteState.CurrentLineLength == 0 && buffer[i] == 46)
            {
                WriteState.Append(46);
                WriteState.Append(buffer[i]);
            }
            else
            {
                WriteState.Append(buffer[i]);
            }
        }
    }
 
    public int DecodeBytes(byte[] buffer, int offset, int count)
    {
        throw new NotImplementedException();
    }
 
    public int EncodeString(string value, Encoding encoding)
    {
        throw new NotImplementedException();
    }
 
    public string GetEncodedString()
    {
        throw new NotImplementedException();
    }
}