Peekable stream reader for .NET/C#

PeekableReader.cs

// better than PeekableStream: less code, less bugs
sealed class PeekableReader : IDisposable
{
    public PeekableReader(Stream stream)
    {
        _stream = stream;
        _byte = _stream.ReadByte();
    }

    public int ReadByte()
    {
        var current = _byte;
        _byte = _stream.ReadByte();
        return current;
    }

    public int PeekByte()
    {
        return _byte;
    }

    public char PeekChar()
    {
        return (char) PeekByte();
    }

    public string TakeWhile(Func<char, bool> predicate)
    {
        var builder = new StringBuilder();
        while (true)
        {
            var raw = PeekByte();
            if (raw == -1)
            {
                break;
            }
            var ch = (char)raw;
            if (!predicate(ch))
            {
                break;
            }
            builder.Append(ch);
            ReadByte();
        }
        return builder.ToString();
    }

    public int SkipWhile(Func<char, bool> predicate)
    {
        var skipped = 0;
        while (true)
        {
            var raw = PeekByte();
            if (raw == -1)
            {
                break;
            }
            var ch = (char) raw;
            if (!predicate(ch))
            {
                break;
            }
            skipped++;
            ReadByte();
        }
        return skipped;
    }

    public void Dispose()
    {
        Dispose(true);

        GC.SuppressFinalize(this);
    }

    private void Dispose(bool disposing)
    {
        if (_disposed)
        {
            return;
        }

        if (disposing)
        {
            if (_stream != null)
            {
                _stream.Dispose();
                _stream = null;
            }
            _disposed = true;
        }
    }

    ~PeekableReader()
    {
        Dispose(false);
    }

    private int _byte;
    private Stream _stream;
    private bool _disposed;
}