/// <summary>
/// Returns the <see cref="DataViewSchema"/> which would be produced by the transformer applied to
/// an input data with schema <paramref name="inputSchema"/>.
/// </summary>
public DataViewSchema GetOutputSchema(DataViewSchema inputSchema)
{
_host.CheckValue(inputSchema, nameof(inputSchema));
var rowToRow = new RowToRowMapper(_host, this, new EmptyDataView(_host, inputSchema));
return(rowToRow.OutputSchema);
}
public Cursor(RowToRowMapper parent, DataViewRowCursor input, bool[] active)
: base(parent.Host, input)
{
Ch.AssertValue(parent);
Ch.Assert(active == null || active.Length == parent.OutputSchema.Count);
_parent = parent;
_active = active;
_getters = new Delegate[parent._parent.AddedSchema.Columns.Length];
var dstRow = new DataViewConstructionUtils.InputRow <TDst>(_parent.Host, _parent._parent.AddedSchema);
IRowReadableAs <TSrc> inputRow = _parent._typedSrc.GetRow(input);
TSrc src = new TSrc();
TState state = new TState();
TDst dst = new TDst();
_parent._parent._stateInitAction(state);
long lastServedPosition = -1;
Action refresh = () =>
{
if (lastServedPosition != input.Position)
{
inputRow.FillValues(src);
_parent._parent._mapAction(src, dst, state);
dstRow.ExtractValues(dst);
lastServedPosition = input.Position;
}
};
for (int i = 0; i < active.Length; i++)
{
var iinfo = _parent._bindings.MapColumnIndex(out var isSrc, i);
if (isSrc)
{
continue;
}
_getters[iinfo] = Utils.MarshalInvoke(_parent.GetDstGetter <int>, _parent._bindings.Schema[i].Type.RawType, dstRow, _parent._bindings.Schema[i].Name, refresh);
}
}
