/// <summary>
/// Executes this operation
/// </summary>
/// <param name="rows">The pre-sorted rows.</param>
/// <returns></returns>
public override IEnumerable <Row> Execute(IEnumerable <Row> rows)
{
ObjectArrayKeys previousKey = null;
var aggregate = new Row();
var groupBy = GetColumnsToGroupBy();
foreach (var row in rows)
{
var key = row.CreateKey(groupBy);
if (previousKey != null && !previousKey.Equals(key))
{
FinishAggregation(aggregate);
yield return(aggregate);
aggregate = new Row();
}
Accumulate(row, aggregate);
previousKey = key;
}
FinishAggregation(aggregate);
yield return(aggregate);
}
/// <summary>
/// Executes this operation
/// </summary>
/// <param name="rows">The pre-sorted rows.</param>
/// <param name="cancellationToken">A CancellationToken to stop execution</param>
/// <returns></returns>
public override IAsyncEnumerable <Row> Execute(IAsyncEnumerable <Row> rows, CancellationToken cancellationToken = default)
{
return(new AsyncEnumerable <Row>(async yield => {
ObjectArrayKeys previousKey = null;
var aggregate = new Row();
var groupBy = GetColumnsToGroupBy();
await rows.ForEachAsync(async row =>
{
var key = row.CreateKey(groupBy);
if (previousKey != null && !previousKey.Equals(key))
{
FinishAggregation(aggregate);
await yield.ReturnAsync(aggregate);
aggregate = new Row();
}
Accumulate(row, aggregate);
previousKey = key;
}, cancellationToken);
FinishAggregation(aggregate);
await yield.ReturnAsync(aggregate);
}));
}