/// <summary>
/// Creates an reaction that observes and runs the given predicate function
/// until it returns true. Once that happens, the given effect function
/// is executed and the reaction is deactivated.<br/>
/// <br/>
/// Returns a reaction, allowing you to cancel it manually.
/// </summary>
/// <param name="lifetime">Reaction lifetime.</param>
/// <param name="data">An observed predicate function.</param>
/// <param name="effect">An effect function.</param>
/// <param name="exceptionHandler">A function that called when an exception is thrown while computing an reaction.</param>
/// <param name="debugName">Debug name for this reaction.</param>
/// <returns>Created reaction.</returns>
/// <example>
///
/// var counter = Atom.Value(1);
///
/// var reaction = Atom.When(Lifetime,
/// () => counter.Value == 10,
/// () => Debug.Log("Counter value equals 10")
/// );
///
/// </example>
public static Reaction When(
Lifetime lifetime,
Func <bool> data,
Action effect,
Action <Exception> exceptionHandler = null,
string debugName = null)
{
var controller = lifetime.CreateNested();
return(Reaction(controller.Lifetime, WhenInternal, debugName: debugName));
void WhenInternal()
{
Exception exception = null;
try
{
if (!data())
{
return;
}
}
catch (Exception e)
{
exception = e;
}
if (exception != null && exceptionHandler == null)
{
Debug.LogException(exception);
return;
}
using (NoWatch)
{
if (exception != null)
{
exceptionHandler(exception);
}
else
{
effect();
}
controller.Dispose();
}
}
}
/// <summary>
/// Creates an reaction that observes and runs the given predicate function
/// until it returns true. Once that happens, the returned task is completed
/// and the reaction is deactivated.<br/>
/// <br/>
/// The task will fail if the predicate throws an exception.
/// </summary>
/// <param name="lifetime">Reaction lifetime.</param>
/// <param name="data">An observed predicate function.</param>
/// <param name="debugName">Debug name for this reaction.</param>
/// <returns>Task that completes when the predicate returns true or predicate function throws exception.</returns>
/// <example>
///
/// var counter = Atom.Value(1);
///
/// await Atom.When(Lifetime, () => counter.Value == 10);
/// Debug.Log("Counter value equals 10");
///
/// </example>
public static Task When(
Lifetime lifetime,
Func <bool> data,
string debugName = null)
{
var controller = lifetime.CreateNested();
var tcs = new TaskCompletionSource <object>();
controller.Register(() => tcs.TrySetCanceled());
Reaction(controller.Lifetime, WhenInternal, debugName: debugName);
return(tcs.Task);
void WhenInternal()
{
Exception exception = null;
try
{
if (!data())
{
return;
}
}
catch (Exception e)
{
exception = e;
}
using (NoWatch)
{
if (exception != null)
{
tcs.TrySetException(exception);
}
else
{
tcs.TrySetResult(null);
}
controller.Dispose();
}
}
}
