sealed record EmptyDataView(DataViewSchema Schema) : IDataView {
	public bool CanShuffle => true;

	public long? GetRowCount() => 0L;

	public DataViewRowCursor GetRowCursor(IEnumerable<DataViewSchema.Column> columnsNeeded, Random? rand = null)
		=> new EmptyDataViewRowCursor(Schema);

	public DataViewRowCursor[] GetRowCursorSet(IEnumerable<DataViewSchema.Column> columnsNeeded, int n, Random? rand = null)
		=> Array.Empty<DataViewRowCursor>();
}

sealed class EmptyDataViewRowCursor : DataViewRowCursor {
	private readonly DataViewSchema schema;

	public EmptyDataViewRowCursor(DataViewSchema Schema) {
		schema = Schema;
	}

	public override DataViewSchema Schema => schema;

	public override long Position => -1L;

	public override bool IsColumnActive(DataViewSchema.Column column) => false;

	public override bool MoveNext() => false;

	public override long Batch => 0L;

	public override ValueGetter<TValue> GetGetter<TValue>(DataViewSchema.Column column)
		=> throw new InvalidOperationException();

	public override ValueGetter<DataViewRowId> GetIdGetter()
		=> throw new InvalidOperationException();
}