/// <summary>
/// Creates an reaction that should run every time anything it observes changes.
/// It also runs once when you create the reaction itself. It only responds
/// to changes in observable state, things you have annotated atom.
/// </summary>
/// <param name="reaction">A function for reaction.</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.Reaction(() =>
/// {
/// Debug.Log("Counter: " + counter.Value);
/// });
///
/// </example>
public static Reaction Reaction(
Action reaction,
Action <Exception> exceptionHandler = null,
string debugName = null)
{
var atom = new ReactionAtom(debugName, reaction, exceptionHandler);
atom.Activate();
return(atom);
}
/// <summary>
/// Creates an reaction that should run every time anything it observes changes.
/// It also runs once when you create the reaction itself. It only responds
/// to changes in observable state, things you have annotated atom.
/// </summary>
/// <param name="lifetime">Reaction lifetime.</param>
/// <param name="reaction">A function for reaction.</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);
///
/// Atom.Reaction(Lifetime, () =>
/// {
/// Debug.Log("Counter: " + counter.Value);
/// });
///
/// </example>
public static Reaction Reaction(
Lifetime lifetime,
Action reaction,
Action<Exception> exceptionHandler = null,
string debugName = null)
{
var atom = new ReactionAtom(debugName, reaction, exceptionHandler);
lifetime.Register(atom);
atom.Activate();
return atom;
}
/// <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="p">An observed predicate function.</param>
/// <param name="sideEffect">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(
/// () => counter.Value == 10,
/// () => Debug.Log("Counter value equals 10")
/// );
///
/// </example>
public static Reaction When(
Func <bool> p,
Action sideEffect,
Action <Exception> exceptionHandler = null,
string debugName = null)
{
Reaction watcher = null;
watcher = new ReactionAtom(debugName, () =>
{
Exception exception = null;
try
{
if (!p())
{
return;
}
}
catch (Exception e)
{
exception = e;
}
if (exception != null && exceptionHandler == null)
{
Debug.LogException(exception);
return;
}
using (NoWatch)
{
if (exception != null)
{
exceptionHandler(exception);
}
else
{
sideEffect();
}
// ReSharper disable once AccessToModifiedClosure
watcher?.Deactivate();
watcher = null;
}
});
watcher.Activate();
return(watcher);
}
/// <summary>
/// Creates an reaction that takes two functions:
/// the first, data function, is tracked and returns the data that is used
/// as input for the second, effect function. It is important to note that
/// the side effect only reacts to data that was accessed in the data function,
/// which might be less than the data that is actually used in the effect function.
///
/// The typical pattern is that you produce the things you need in your side effect
/// in the data function, and in that way control more precisely when the effect triggers.
/// </summary>
/// <param name="reaction">A data function.</param>
/// <param name="effect">A side effect function.</param>
/// <param name="exceptionHandler">A function that called when an exception is thrown while computing an reaction.</param>
/// <param name="comparer">Data comparer used for reconciling.</param>
/// <param name="fireImmediately">Should the side effect runs once when you create a reaction itself? Default value is true.</param>
/// <param name="debugName">Debug name for this reaction.</param>
/// <typeparam name="T">Reaction data type.</typeparam>
/// <returns>Created reaction.</returns>
/// <example>
///
/// var counter = Atom.Value(1);
///
/// var reaction = Atom.Reaction(
/// () => counter.Value,
/// (val, reactionHandle) =>
/// {
/// Debug.Log("Counter: " + val);
/// if (val == 10)
/// {
/// reactionHandle.Deactivate();
/// }
/// }
/// );
///
/// </example>
public static Reaction Reaction <T>(
AtomPull <T> reaction,
Action <T, Reaction> effect,
Action <Exception> exceptionHandler = null,
IEqualityComparer <T> comparer = null,
bool fireImmediately = true,
string debugName = null)
{
var valueAtom = Computed(reaction, comparer: comparer);
bool firstRun = true;
Reaction atom = null;
atom = new ReactionAtom(debugName, () =>
{
var value = valueAtom.Value;
using (NoWatch)
{
if (firstRun)
{
firstRun = false;
if (!fireImmediately)
{
return;
}
}
// ReSharper disable once AccessToModifiedClosure
effect(value, atom);
}
}, exceptionHandler);
atom.Activate();
return(atom);
}
/// <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="p">An observed predicate function.</param>
/// <param name="cancellationToken">Token for reaction cancellation.</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(() => counter.Value == 10);
/// Debug.Log("Counter value equals 10");
///
/// </example>
public static Task When(
Func <bool> p,
CancellationToken cancellationToken = default,
string debugName = null)
{
var taskCompletionSource = new TaskCompletionSource <object>();
Reaction watcher = null;
CancellationTokenRegistration?cancellationTokenRegistration = null;
void Dispose()
{
taskCompletionSource.TrySetCanceled();
// ReSharper disable once AccessToModifiedClosure
cancellationTokenRegistration?.Dispose();
// ReSharper disable once AccessToModifiedClosure
watcher?.Deactivate();
watcher = null;
}
watcher = new ReactionAtom(debugName, () =>
{
Exception exception = null;
try
{
if (!p())
{
return;
}
}
catch (Exception e)
{
exception = e;
}
using (NoWatch)
{
if (exception != null)
{
taskCompletionSource.TrySetException(exception);
}
else
{
taskCompletionSource.TrySetResult(null);
}
Dispose();
}
});
if (cancellationToken.IsCancellationRequested)
{
Dispose();
}
else
{
watcher.Activate();
if (cancellationToken.CanBeCanceled)
{
cancellationTokenRegistration = cancellationToken.Register(Dispose, true);
}
}
return(taskCompletionSource.Task);
}