public bool MoveNext ()
{
if (host.modificationCount != stamp || invalid)
throw new InvalidOperationException (xstr);
Slot [] table = host.table;
if (++pos < size) {
Slot entry = table [pos];
currentKey = entry.key;
currentValue = entry.value;
return true;
}
currentKey = null;
currentValue = null;
return false;
}