/// <summary>
/// Merge a sequence of producers into a single producer
/// </summary>
/// <remarks>The merged producer completes when all component producers have completed</remarks>
/// <param name="ms">Sequence of producers to merge</param>
/// <returns>Merged producers</returns>
public static Producer <RT, OUT, A> merge <RT, OUT, A>(Seq <Producer <RT, OUT, A> > ms) where RT : struct, HasCancel <RT>
{
return(from e in Producer.lift <RT, OUT, RT>(runtime <RT>())
from x in Producer.enumerate2 <RT, OUT>(go(e))
from _ in Producer.yield <RT, OUT>(x)
select default(A));
async IAsyncEnumerable <OUT> go(RT env)
{
var queue = new ConcurrentQueue <OUT>();
var wait = new AutoResetEvent(true);
var running = true;
// Create a consumer that simply awaits a value and then puts it in our concurrent queue
// to be re-yielded
var enqueue = Consumer.awaiting <RT, OUT>()
.Map(x =>
{
queue.Enqueue(x);
wait.Set();
return(default(A));
})
.ToConsumer();
// Compose the enqueue Consumer with the Producer to create an Effect that can be run
var mme = ms.Map(m => m | enqueue).Strict();
// Run the producing effects
// We should NOT be awaiting these
var mmt = mme.Map(m => m.RunEffect().Run(env).AsTask());
// When all tasks are done, we're done
// We should NOT be awaiting this
#pragma warning disable CS4014
Task.WhenAll(mmt.ToArray())
.Iter(_ =>
{
running = false;
wait.Set();
});
#pragma warning restore CS4014
// Keep processing until we're cancelled or all of the Producers have stopped producing
while (running && !env.CancellationToken.IsCancellationRequested)
{
await wait.WaitOneAsync(env.CancellationToken).ConfigureAwait(false);
while (queue.TryDequeue(out var item))
{
yield return(item);
}
}
}
}
/// <summary>
/// Folds values coming down-stream, when the predicate returns true the folded value is yielded
/// </summary>
/// <param name="Initial">Initial state</param>
/// <param name="Fold">Fold operation</param>
/// <param name="UntilValue">Predicate</param>
/// <returns>A pipe that folds</returns>
public static Producer <RT, S, Unit> FoldWhile <RT, S, A>(this Producer <RT, S, A> ma, S Initial, Func <S, A, S> Fold, Func <S, bool> WhileState)
where RT : struct, HasCancel <RT>
{
var state = Initial;
return(ma.Bind(
x =>
{
state = Fold(state, x);
if (WhileState(state))
{
return Producer.Pure <RT, S, Unit>(unit);
}
else
{
var nstate = state;
state = Initial;
return Producer.yield <RT, S>(nstate);
}
}));
}
/// <summary>
/// Folds values coming down-stream, when the predicate returns true the folded value is yielded
/// </summary>
/// <param name="Initial">Initial state</param>
/// <param name="Fold">Fold operation</param>
/// <param name="UntilValue">Predicate</param>
/// <returns>A pipe that folds</returns>
public static Producer <RT, S, Unit> FoldUntil <RT, S, A>(this Producer <RT, S, A> ma, S Initial, Func <S, A, S> Fold, Func <A, bool> UntilValue)
where RT : struct, HasCancel <RT>
{
var state = Initial;
return(ma.Bind(
x =>
{
if (UntilValue(x))
{
var nstate = state;
state = Initial;
return Producer.yield <RT, S>(nstate);
}
else
{
state = Fold(state, x);
return Producer.Pure <RT, S, Unit>(unit);
}
}));
}
