// Calculate an offset from the row and mode, returning the ordinal of some other row
// This is required to be within the same group (no key break)
public int Offset(DataRow row, int index, OffsetModes mode)
{
if (index < 0)
{
return(-1);
}
var key = BuildKey(row, row.Order);
var xofk = _slist.IndexOfKey(key);
var xofkx = (mode == OffsetModes.Lead) ? xofk + index
: (mode == OffsetModes.Lag) ? xofk - index
: (mode == OffsetModes.Absolute) ? _firstkeyx + index
: index;
if (!(xofkx >= _firstkeyx && xofkx < _slist.Count))
{
return(-1);
}
// Are these keys in the same group?
if (IsKeyBreak(_slist.Keys[xofk], _slist.Keys[xofkx]))
{
return(-1);
}
//if (_groupseg >= 0) {
// var v1 = _slist.Keys[xofk][_groupseg] as TypedValue;
// var v2 = _slist.Keys[xofkx][_groupseg] as TypedValue;
// if (!v1.Equals(v2)) return -1; // BUG: must compare all prior segs
//}
return(_slist.Values[xofkx]);
}
// Return value of attribute with tuple indexing
// FIX: needs to get from this row to some other row via parent table to use as lookup
public TypedValue ValueOffset(ExpressionEval expr, int index, OffsetModes mode)
{
var parent = Parent as DataTableLocal;
Logger.Assert(parent != null);
var ord = OrderedIndex.Offset(this, index, mode);
var value = (ord == -1) ? expr.ReturnType.DefaultValue()
: expr.EvalOpen(parent.GetRow(ord));
return(value);
}
