/// <summary>
/// Advances the stream by a number of positions and returns the original position.
/// </summary>
/// <param name="count">The number of positions to advance.</param>
/// <exception cref="InvalidOperationException">
/// Thrown if the position will fall outside the bounds of the underlying array segment.
/// </exception>
/// <returns>the position of the stream before advancing.</returns>
private int CheckedAdvance(int count)
{
if (_currentOffset + count > _segmentEnd)
{
throw PacketReadingException.EndOfStream();
}
int old = _currentOffset;
_currentOffset += count;
return(old);
}
/// <inheritdoc />
/// <inheritdoc cref="CheckedAdvance" select="exception[@cref='PacketReadingException']" />
public string ReadLengthString()
{
// We do this in a convoluted fashion to avoid moving the position forward if we're gonna fail.
short length = ReadInt16(true);
if (!CanAdvance(2 + length))
{
throw PacketReadingException.EndOfStream();
}
string s = ReadString(_currentOffset + 2, length);
_currentOffset += 2 + length;
return(s);
}
private short ReadInt16(bool peek)
{
int start;
if (peek)
{
// If we just wanna peek, don't advance.
if (!CanAdvance(2))
{
throw PacketReadingException.EndOfStream();
}
start = _currentOffset;
}
else
{
// Otherwise do advance.
start = CheckedAdvance(2);
}
return(LittleEndianBitConverter.ToInt16(_buffer, start));
}