public void AnyChange_NoSources_ReturnsNull()
{
// Act
var signal = new IReadableSignal <Unit> [0].AnyChange();
// Assert
Assert.Null(signal);
}
/// <summary>
/// Projects the <paramref name="source"/> signal into a new signal
/// using the <paramref name="selector"/> function and flattens the result into a new signal.
/// </summary>
public static IReadableSignal <TResult> SelectMany <TSource, TResult>(
this IReadableSignal <TSource> source,
Func <TSource, IReadableSignal <TResult> > selector)
{
CheckValue(source, nameof(source));
CheckValue(selector, nameof(selector));
return(source.Select(selector).Flatten());
}
/// <summary>
/// Creates a delayable signal that can postpone applying updates to a wrapped signal.
/// </summary>
public static DelayableSignal <T> ToDelayable <T>(this IReadableSignal <T> source)
{
CheckValue(source, nameof(source));
var result = new DelayableSignal <T>(source.Context);
Update();
return(result);
void Update()
{
var snapshot = source.GetSnapshot();
result.Value = snapshot.Value;
snapshot.OnChange(Update);
}
}
/// <summary>
/// Flattens a nested signal into a new signal.
/// </summary>
public static IReadableSignal <T> Flatten <T>(this IReadableSignal <IReadableSignal <T> > source)
{
CheckValue(source, nameof(source));
var result = new Signal <T>(source.Context);
ISignalSnapshot <IReadableSignal <T> > outerSnapshot;
IDisposable innerSubscription = null;
OnOuterChanged();
return(result);
void OnOuterChanged()
{
// If we were subscribed to a different signal, we don't care about it anymore since the outer changed.
innerSubscription?.Dispose();
outerSnapshot = source.GetSnapshot();
if (outerSnapshot.Value is null)
{
result.Value = default;
innerSubscription = null;
}
else
{
if (!ReferenceEquals(outerSnapshot.Value.Context, source.Context))
{
throw new InvalidOperationException($"Mismatched {nameof(SignalContext)}'s. Cannot mix signals created from different factories.");
}
var innerSnapshot = outerSnapshot.Value.GetSnapshot();
result.Value = innerSnapshot.Value;
innerSubscription = innerSnapshot.OnChange(OnInnerChanged);
}
outerSnapshot.OnChange(OnOuterChanged);
}
void OnInnerChanged()
{
// No need to unsubscribe, the old subscription will never fire again and GC will clean things up eventually
var innerSnapshot = outerSnapshot.Value.GetSnapshot();
result.Value = source.Value.Value;
innerSubscription = innerSnapshot.OnChange(OnInnerChanged);
}
}
/// <summary>
/// Projects the <paramref name="source"/> signal into a new signal
/// using the <paramref name="selector"/> function.
/// </summary>
public static IReadableSignal <TResult> Select <TSource, TResult>(
this IReadableSignal <TSource> source,
Func <TSource, TResult> selector)
{
CheckValue(source, nameof(source));
CheckValue(selector, nameof(selector));
var result = new Signal <TResult>(source.Context);
Update();
return(result);
void Update()
{
var snapshot = source.GetSnapshot();
result.Value = selector(snapshot.Value);
snapshot.OnChange(Update);
}
}
/// <summary>
/// Projects the <paramref name="source"/> signal into a new signal
/// that reacts to all changes but drops the original value.
/// </summary>
public static IReadableSignal <Unit> DropValue <T>(this IReadableSignal <T> source)
{
CheckValue(source, nameof(source));
return(source.Select(value => Unit.Instance));
}
