private async Task <IAsyncEnumerable <Row> > GetRightEnumerable(CancellationToken cancellationToken = default)
{
IAsyncEnumerable <Row> rightEnumerable = new CachingEnumerable <Row>(new EventRaisingEnumerator(right, right.Execute(null, cancellationToken)),
cancellationToken);
await rightEnumerable.ForEachAsync(row =>
{
ObjectArrayKeys key = row.CreateKey(rightColumns);
List <Row> rowsForKey;
if (this.rightRowsByJoinKey.TryGetValue(key, out rowsForKey) == false)
{
this.rightRowsByJoinKey[key] = rowsForKey = new List <Row>();
}
rowsForKey.Add(row);
}, cancellationToken);
return(rightEnumerable);
}
/// <summary>
/// Executes this operation
/// </summary>
/// <param name="rows">Rows in pipeline. These are only used if a left part of the join was not specified.</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 => {
PrepareForJoin();
Dictionary <Row, object> matchedRightRows = new Dictionary <Row, object>();
CachingEnumerable <Row> rightEnumerable = new CachingEnumerable <Row>(
new EventRaisingEnumerator(right, right.Execute(null, cancellationToken)), cancellationToken);
IAsyncEnumerable <Row> execute = left.Execute(leftRegistered ? null : rows, cancellationToken);
await new EventRaisingEnumerator(left, execute)
.ForEachAsync(async leftRow =>
{
bool leftNeedOuterJoin = true;
currentLeftRow = leftRow;
await rightEnumerable.ForEachAsync(async rightRow =>
{
currentRightRow = rightRow;
if (MatchJoinCondition(leftRow, rightRow))
{
leftNeedOuterJoin = false;
matchedRightRows[rightRow] = null;
await yield
.ReturnAsync(MergeRows(leftRow,
rightRow));
}
}, cancellationToken);
if (leftNeedOuterJoin)
{
Row emptyRow = new Row();
emptyRow[IsEmptyRowMarker] = IsEmptyRowMarker;
currentRightRow = emptyRow;
if (MatchJoinCondition(leftRow, emptyRow))
{
await yield.ReturnAsync(MergeRows(leftRow, emptyRow));
}
else
{
LeftOrphanRow(leftRow);
}
}
}, cancellationToken);
await rightEnumerable.ForEachAsync(async rightRow =>
{
if (matchedRightRows.ContainsKey(rightRow))
{
return;
}
currentRightRow = rightRow;
Row emptyRow = new Row();
emptyRow[IsEmptyRowMarker] = IsEmptyRowMarker;
currentLeftRow = emptyRow;
if (MatchJoinCondition(emptyRow, rightRow))
{
await yield.ReturnAsync(MergeRows(emptyRow, rightRow));
}
else
{
RightOrphanRow(rightRow);
}
}, cancellationToken);
}));
}
