/// <summary>
/// Emits a zero-argument operation. Note that the emit
/// functions all run in two modes: they can emit code, or
/// they can just count the size of the code.
/// </summary>
private void Emit(int op)
{
if (RegexCode.OpcodeBacktracks(op))
{
_trackCount++;
}
_emitted.Append(op);
}