/// <summary>
/// Add a decorator to the enumerable for additional processing
/// </summary>
/// <param name="operation">The operation.</param>
/// <param name="enumerator">The enumerator.</param>
/// <param name="cancellationToken">A <see cref="T:System.Threading.CancellationToken" /> that may be used to cancel the asynchronous iteration.</param>
protected override AsyncEnumerableTask <Row> DecorateEnumerableForExecution(
IOperation operation,
IAsyncEnumerable <Row> enumerator,
CancellationToken cancellationToken = default)
{
return(AsyncEnumerableTask <Row> .Completed(new CachingEnumerable <Row>(new EventRaisingEnumerator(operation, enumerator), cancellationToken)));
}
/// <summary>
/// Add a decorator to the enumerable for additional processing
/// </summary>
/// <param name="operation">The operation.</param>
/// <param name="enumerator">The enumerator.</param>
/// <param name="cancellationToken">A <see cref="T:System.Threading.CancellationToken" /> that may be used to cancel the asynchronous iteration.</param>
protected override AsyncEnumerableTask <Row> DecorateEnumerableForExecution(IOperation operation,
IAsyncEnumerable <Row> enumerator,
CancellationToken cancellationToken = default)
{
return(AsyncEnumerableTask <Row> .Completed(new AsyncEnumerable <Row>(async yield =>
{
await new EventRaisingEnumerator(operation, enumerator)
.ForEachAsync(async row => { await yield.ReturnAsync(row); }, cancellationToken);
})));
}
/// <summary>
/// Transform the pipeline to an enumerable
/// </summary>
/// <param name="pipeline">The pipeline.</param>
/// <param name="rows">The rows</param>
/// <param name="translateEnumerable">Translate the rows from one representation to another</param>
/// <param name="cancellationToken">A CancellationToken to stop execution</param>
/// <returns></returns>
public virtual IAsyncEnumerable <Row> PipelineToEnumerable(
ICollection <IOperation> pipeline,
IAsyncEnumerable <Row> rows,
Func <IAsyncEnumerable <Row>, IAsyncEnumerable <Row> > translateEnumerable,
CancellationToken cancellationToken = default)
{
IList <Task> tasks = new List <Task>();
foreach (var operation in pipeline)
{
operation.PrepareForExecution(this);
var enumerator = operation.Execute(rows, cancellationToken);
enumerator = translateEnumerable(enumerator);
AsyncEnumerableTask <Row> task = DecorateEnumerableForExecution(operation, enumerator, cancellationToken);
rows = task.Enumerable;
tasks.Add(task.Task);
}
Task.WaitAll(tasks.ToArray());
return(rows);
}
