Signal WIP

src/Library/Signal.Tests/CombineAllTests.cs

@@ -0,0 +1,22 @@
+using Xunit;
+
+namespace Signal.Tests;
+
+public class CombineAllTests
+{
+    [Fact]
+    public async Task GetValueAsync_WhenParentSometimesReturnsNull_ShouldInitialize()
+    {
+        int count = 0;
+        // Arrange
+        var signal1 = new Signal<string>(null);
+        var signal2 = new Signal<string>(null);
+        var combineAll = new CombineAllSignal<string, string>([signal1, signal2], _ => "TEST");
+
+        // Act
+        var result = await combineAll.GetValueAsync();
+
+        // Assert
+        Assert.Equal("TEST", result);
+    }
+}

src/Library/Signal.Tests/DebounceTests.cs

@@ -0,0 +1,33 @@
+using Xunit;
+
+namespace Signal.Tests;
+
+public class DebounceTests
+{
+    [Fact]
+    public async Task Debounce_WhenCalled_ReturnsDebouncedValue()
+    {
+        // Arrange
+        var signal = new Signal<int>(1);
+        var debouncedSignal = signal.Debounce(TimeSpan.FromMilliseconds(100));
+
+        // Act
+        var result1 = await debouncedSignal.GetValueAsync();
+        await signal.SetValueAsync(2);
+        var result2 = await debouncedSignal.GetValueAsync();
+        await signal.SetValueAsync(3);
+        var result3_1 = await debouncedSignal.GetValueAsync();
+
+        await Task.Delay(300);
+        var result3_2 = await debouncedSignal.GetValueAsync();
+        await signal.SetValueAsync(4);
+        var result4 = await debouncedSignal.GetValueAsync();
+
+        // Assert
+        Assert.Equal(1, result1);
+        Assert.Equal(1, result2);
+        Assert.Equal(1, result3_1);
+        Assert.Equal(3, result3_2);
+        Assert.Equal(3, result4);
+    }
+}

src/Library/Signal.Tests/MapSignalTests.cs

@@ -76,4 +76,19 @@ public class MapSignalTests
         // Assert
         Assert.Equal("TEST", result);
     }
+
+    [Fact]
+    public async Task GetValueAsync_WhenParentSometimesReturnsNull_ShouldInitialize()
+    {
+        int count = 0;
+        // Arrange
+        var signal = new Signal<string>(null);
+        var mapped = signal.Map(_ => "TEST");
+        
+        // Act
+        var result = await mapped.GetValueAsync();
+        
+        // Assert
+        Assert.Equal("TEST", result);
+    }
 }

src/Library/Signal/CombineAllSignal.cs

@@ -0,0 +1,69 @@
+namespace Signal;
+
+public class CombineAllSignal<T, TResult> : SignalBase<TResult>
+{
+    private readonly IReadOnlyList<SignalBase<T>> _parentSignals;
+    private readonly Func<ICollection<T>, ValueTask<TResult>> _combiner;
+    private readonly T[] _lastParentResults;
+    private readonly T[] _currentParentResults;
+    private TResult? _lastResult;
+    private bool _isInitialized;
+
+    public CombineAllSignal(ICollection<SignalBase<T>> parentSignals, Func<ICollection<T>, TResult> combiner) :
+        base(parentSignals)
+    {
+        _parentSignals = parentSignals.ToList();
+        _combiner = c => new ValueTask<TResult>(combiner(c));
+
+        _lastParentResults = new T[_parentSignals.Count];
+        _currentParentResults = new T[_parentSignals.Count];
+    }
+
+    public CombineAllSignal(ICollection<SignalBase<T>> parentSignals, Func<ICollection<T>, ValueTask<TResult>> combiner) :
+        base(parentSignals)
+    {
+        _parentSignals = parentSignals.ToList();
+        _combiner = combiner;
+
+        _lastParentResults = new T[_parentSignals.Count];
+        _currentParentResults = new T[_parentSignals.Count];
+    }
+
+    protected override async ValueTask<TResult> GetValueInternalAsync()
+    {
+        if (!IsDirty)
+        {
+            return _lastResult!;
+        }
+
+        IsDirty = false;
+
+        if (_isInitialized)
+        {
+            bool anyChanged = false;
+            for (var i = 0; i < _parentSignals.Count; i++)
+            {
+                var parentSignal = _parentSignals[i];
+                var newResult = await parentSignal.GetValueAsync();
+                _currentParentResults[i] = newResult;
+
+                if ((newResult == null && _lastParentResults[i] != null)
+                    || (newResult != null && newResult.Equals(_lastParentResults[i])))
+                {
+                    anyChanged = true;
+                }
+            }
+
+            if (!anyChanged)
+            {
+                return _lastResult!;
+            }
+        }
+
+        _isInitialized = true;
+        Array.Copy(_currentParentResults, _lastParentResults, _currentParentResults.Length);
+        var result = await _combiner(_currentParentResults);
+        _lastResult = result;
+        return result;
+    }
+}

src/Library/Signal/CombineLatestSignal.cs

@@ -38,6 +38,7 @@ public sealed class CombineLatestSignal<T1, T2, TResult> : SignalBase<TResult>
             return _result;
         }
         
+        // TODO caching
         IsDirty = false;
         _result = await _combine();
         return _result;

src/Library/Signal/DebounceSignal.cs

@@ -0,0 +1,83 @@
+namespace Signal;
+
+public class DebounceSignal<T> : SignalBase<T>
+{
+    private readonly object _debounceTaskLock = new();
+    private readonly SignalBase<T> _parentSignal;
+    private bool _isDebounceRunning;
+    private DateTime _debounceStartedAt;
+    private readonly Func<TimeSpan> _interval;
+    private T? _lastParentValue;
+
+    public bool ResetTimer { get; init; }
+    public TimeSpan WaitInterval { get; init; } = TimeSpan.FromMilliseconds(10);
+    
+    public override bool IsDirty
+    {
+        get => base.IsDirty;
+        protected set
+        {
+            if(!value)
+            {
+                base.IsDirty = value;
+                return;
+            }
+
+            lock (_debounceTaskLock)
+            {
+                if (_isDebounceRunning)
+                {
+                    if (ResetTimer)
+                    {
+                        _debounceStartedAt = DateTime.Now;
+                    }
+
+                    return;
+                }
+                _isDebounceRunning = true;
+                _debounceStartedAt = DateTime.Now;
+                Task.Run(StartDebouncing);
+            }
+        }
+    }
+
+    async Task StartDebouncing()
+    {
+        while (DateTime.Now - _debounceStartedAt < _interval())
+        {
+            await Task.Delay(WaitInterval);
+        }
+        
+        base.IsDirty = true;
+        lock (_debounceTaskLock)
+        {
+            _isDebounceRunning = false;
+        }
+    }
+
+    public DebounceSignal(SignalBase<T> parentSignal, Func<TimeSpan> interval) : base(parentSignal)
+    {
+        _parentSignal = parentSignal;
+        _interval = interval;
+    }
+    
+    protected override async ValueTask<T> GetValueInternalAsync()
+    {
+        if (!IsDirty)
+        {
+            return _lastParentValue!;
+        }
+
+        IsDirty = false;
+        var baseValue = await _parentSignal.GetValueAsync();
+        if (
+            (_lastParentValue == null && baseValue == null) ||
+            (baseValue != null && baseValue.Equals(_lastParentValue)))
+        {
+            return _lastParentValue!;
+        }
+
+        _lastParentValue = baseValue;
+        return _lastParentValue;
+    }
+}

src/Library/Signal/Extensions.cs

@@ -6,8 +6,19 @@ public static class Extensions
     {
         return new MapSignal<T, TResult>(signal, map);
     }
+
     public static SignalBase<TResult> Map<T, TResult>(this SignalBase<T> signal, Func<T, Task<TResult>> map)
     {
         return new MapSignal<T, TResult>(signal, map);
     }
+
+    public static SignalBase<T> Debounce<T>(this SignalBase<T> signal, TimeSpan interval)
+    {
+        return new DebounceSignal<T>(signal, () => interval);
+    }
+
+    public static SignalBase<T> Debounce<T>(this SignalBase<T> signal, Func<TimeSpan> interval)
+    {
+        return new DebounceSignal<T>(signal, interval);
+    }
 }

src/Library/Signal/MapSignal.cs

@@ -4,6 +4,7 @@ public sealed class MapSignal<T, TResult> : SignalBase<TResult>
 {
     private readonly Func<T, ValueTask<TResult>> _map;
     private readonly SignalBase<T> _parentSignal;
+    private bool _isInitialized;
     private T? _lastParentValue;
     private TResult? _lastResult;
 
@@ -43,12 +44,17 @@ public sealed class MapSignal<T, TResult> : SignalBase<TResult>
         IsDirty = false;
         var baseValue = await _parentSignal.GetValueAsync();
         if (
-            (_lastParentValue == null && baseValue == null) ||
-            (baseValue != null && baseValue.Equals(_lastParentValue)))
+            _isInitialized 
+            &&
+            (
+                (baseValue == null && _lastParentValue == null) 
+                || (baseValue != null && baseValue.Equals(_lastParentValue))
+            ))
         {
             return _lastResult!;
         }
 
+        _isInitialized = true;
         _lastParentValue = baseValue;
         _lastResult = await _map(baseValue);
         return _lastResult;

src/Library/Signal/SignalBase.cs

@@ -6,7 +6,7 @@ public abstract class SignalBase : IReadOnlySignal
 
     public event Action<bool>? IsDirtyChanged;
 
-    public bool IsDirty
+    public virtual bool IsDirty
     {
         get => _isDirty;
         protected set
@@ -20,6 +20,7 @@ public abstract class SignalBase : IReadOnlySignal
             IsDirtyChanged?.Invoke(value);
         }
     }
+
     public event Action<SignalBase> Disposed;
     public bool IsDisposed { get; private set; }
 
@@ -41,16 +42,17 @@ public abstract class SignalBase : IReadOnlySignal
 public abstract class SignalBase<T> : SignalBase, IReadOnlySignal<T>
 {
     internal static AsyncLocal<TreeLocker> CurrentTreeLocker { get; } = new();
-    private protected SignalBase():base(new TreeLocker())
+
+    private protected SignalBase() : base(new TreeLocker())
     {
     }
 
-    protected SignalBase(SignalBase parentSignal):base(parentSignal.TreeLock)
+    protected SignalBase(SignalBase parentSignal) : base(parentSignal.TreeLock)
     {
         SubscribeToParentSignalChanges(parentSignal);
     }
 
-    protected SignalBase(ICollection<SignalBase> parentSignals):base(CreateMultiParentTreeLock(parentSignals))
+    protected SignalBase(ICollection<SignalBase> parentSignals) : base(CreateMultiParentTreeLock(parentSignals))
     {
         ArgumentOutOfRangeException.ThrowIfZero(parentSignals.Count);
 
@@ -60,7 +62,20 @@ public abstract class SignalBase<T> : SignalBase, IReadOnlySignal<T>
         }
     }
 
-    private static TreeLocker CreateMultiParentTreeLock(ICollection<SignalBase> parentSignals)
+    protected SignalBase(IEnumerable<SignalBase> parentSignals) : base(CreateMultiParentTreeLock(parentSignals))
+    {
+        if (!parentSignals.Any())
+        {
+            throw new ArgumentOutOfRangeException(nameof(parentSignals));
+        }
+
+        foreach (var parentSignal in parentSignals)
+        {
+            SubscribeToParentSignalChanges(parentSignal);
+        }
+    }
+
+    private static TreeLocker CreateMultiParentTreeLock(IEnumerable<SignalBase> parentSignals)
     {
         var firstLock = parentSignals.First().TreeLock;
         foreach (var parentSignal in parentSignals.Skip(1))