/// <summary>
/// Sends an element to the stream subscriber. You are allowed to send as many elements
/// as have been requested by the stream subscriber. This amount can be inquired with
/// <see cref="TotalDemand"/>. It is only allowed to use <see cref="OnNext"/> when
/// <see cref="IsActive"/> and <see cref="TotalDemand"/> > 0,
/// otherwise <see cref="OnNext"/> will throw <see cref="IllegalStateException"/>.
/// </summary>
/// <param name="element">TBD</param>
/// <exception cref="IllegalStateException">
/// This exception is thrown for a number of reasons. These include:
/// <dl>
/// <dt>when in the <see cref="LifecycleState.Active"/> or <see cref="LifecycleState.PreSubscriber"/> state</dt>
/// <dd>This exception is thrown when the <see cref="ActorPublisher{T}"/> has zero <see cref="TotalDemand"/>.</dd>
/// <dt>when in the <see cref="LifecycleState.ErrorEmitted"/> state</dt>
/// <dd>This exception is thrown when this <see cref="ActorPublisher{T}"/> has already terminated due to an error.</dd>
/// <dt>when in the <see cref="LifecycleState.Completed"/> or <see cref="LifecycleState.CompleteThenStop"/> state</dt>
/// <dd>This exception is thrown when this <see cref="ActorPublisher{T}"/> has already completed.</dd>
/// </dl>
/// </exception>
public void OnNext(T element)
{
switch (_lifecycleState)
{
case LifecycleState.Active:
case LifecycleState.PreSubscriber:
if (_demand > 0)
{
_demand--;
ReactiveStreamsCompliance.TryOnNext(_subscriber, element);
}
else
{
throw new IllegalStateException(
"OnNext is not allowed when the stream has not requested elements, total demand was 0");
}
break;
case LifecycleState.ErrorEmitted:
throw new IllegalStateException("OnNext must not be called after OnError");
case LifecycleState.Completed:
case LifecycleState.CompleteThenStop:
throw new IllegalStateException("OnNext must not be called after OnComplete");
case LifecycleState.Canceled: break;
}
}
private void OnNext(T element)
{
_downstreamDemand--;
ReactiveStreamsCompliance.TryOnNext(_subscriber, element);
}