private int _cch; // length of the current span
internal SpanRider(SpanVector <T> vector)
{
_defaultSpan = new Span <T>(vector.DefaultValue, MaxCch);
_vector = vector;
_current = 0;
_cp = 0;
_dcp = 0;
_cch = 0;
At(0);
}
internal SpanEnumerator(SpanVector <U> vector)
{
_vector = vector;
_current = -1;
}