Enhanced Observable functionality

The ObservePropertyChanged and ObservePropertyChanging methods now support multiple property selectors, allowing for nested observation of property changes. Corresponding unit tests have also been added.
Cysharp · Mar 4, 2024 · 996bc83 · 996bc83
1 parent 62ab623
commit 996bc83
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diff --git a/src/R3/Factories/ObserveProperty.cs b/src/R3/Factories/ObserveProperty.cs
@@ -1,4 +1,4 @@
-using System.ComponentModel;
+using System.ComponentModel;
 using System.Runtime.CompilerServices;
 
 namespace R3;
@@ -24,7 +24,7 @@ public static Observable<TProperty> ObservePropertyChanged<T, TProperty>(this T
 
     /// <summary>
     /// Convert INotifyPropertyChanged to Observable.
-    /// `propertySelector` must be a Func specifying a simple property. For example, it extracts "Foo" from `x => x.Foo`.
+    /// `propertySelector1` and `propertySelector2` must be a Func specifying a simple property. For example, it extracts "Foo" from `x => x.Foo`.
     /// </summary>
     public static Observable<TProperty2> ObservePropertyChanged<T, TProperty1, TProperty2>(this T value,
         Func<T, TProperty1> propertySelector1,
@@ -42,16 +42,61 @@ public static Observable<TProperty2> ObservePropertyChanged<T, TProperty1, TProp
         var property1Name = propertySelector1Expr!.Substring(propertySelector1Expr.LastIndexOf('.') + 1);
         var property2Name = propertySelector2Expr!.Substring(propertySelector2Expr.LastIndexOf('.') + 1);
 
-        var firstPropertyChanged = new ObservePropertyChanged<T, TProperty1>(value, propertySelector1, property1Name, pushCurrentValueOnSubscribe, cancellationToken);
-
-        return firstPropertyChanged
+        return new ObservePropertyChanged<T, TProperty1>(value, propertySelector1, property1Name, true, cancellationToken)
             .Select(
                 (propertySelector2, property2Name, pushCurrentValueOnSubscribe, cancellationToken),
                 (firstPropertyValue, state) =>
-                    (Observable<TProperty2>)new ObservePropertyChanged<TProperty1, TProperty2>(firstPropertyValue, state.propertySelector2, state.property2Name, state.pushCurrentValueOnSubscribe, state.cancellationToken))
+                    firstPropertyValue is not null
+                        ? new ObservePropertyChanged<TProperty1, TProperty2>(firstPropertyValue,
+                            state.propertySelector2, state.property2Name, state.pushCurrentValueOnSubscribe,
+                            state.cancellationToken)
+                        : Empty<TProperty2>())
             .Switch();
     }
 
+    /// <summary>
+    /// Convert INotifyPropertyChanged to Observable.
+    /// `propertySelector1`, `propertySelector2`, and `propertySelector3` must be a Func specifying a simple property. For example, it extracts "Foo" from `x => x.Foo`.
+    /// </summary>
+    public static Observable<TProperty3> ObservePropertyChanged<T, TProperty1, TProperty2, TProperty3>(this T value,
+        Func<T, TProperty1> propertySelector1,
+        Func<TProperty1, TProperty2> propertySelector2,
+        Func<TProperty2, TProperty3> propertySelector3,
+        bool pushCurrentValueOnSubscribe = true,
+        CancellationToken cancellationToken = default,
+        [CallerArgumentExpression(nameof(propertySelector1))] string? propertySelector1Expr = null,
+        [CallerArgumentExpression(nameof(propertySelector2))] string? propertySelector2Expr = null,
+        [CallerArgumentExpression(nameof(propertySelector3))] string? propertySelector3Expr = null)
+        where T : INotifyPropertyChanged
+        where TProperty1 : INotifyPropertyChanged
+        where TProperty2 : INotifyPropertyChanged
+    {
+        if (propertySelector1Expr == null) throw new ArgumentNullException(propertySelector1Expr);
+        if (propertySelector2Expr == null) throw new ArgumentNullException(propertySelector2Expr);
+        if (propertySelector3Expr == null) throw new ArgumentNullException(propertySelector3Expr);
+
+        var property1Name = propertySelector1Expr!.Substring(propertySelector1Expr.LastIndexOf('.') + 1);
+        var property2Name = propertySelector2Expr!.Substring(propertySelector2Expr.LastIndexOf('.') + 1);
+        var property3Name = propertySelector3Expr!.Substring(propertySelector3Expr.LastIndexOf('.') + 1);
+
+        return new ObservePropertyChanged<T, TProperty1>(value, propertySelector1, property1Name, true, cancellationToken)
+            .Select(
+                (propertySelector2, property2Name, propertySelector3, property3Name, pushCurrentValueOnSubscribe, cancellationToken),
+                (firstPropertyValue, state) =>
+                    firstPropertyValue is not null
+                        ? new ObservePropertyChanged<TProperty1, TProperty2>(firstPropertyValue, state.propertySelector2, state.property2Name, true, state.cancellationToken)
+                            .Select(
+                                (state.propertySelector3, state.property3Name, pushCurrentValueOnSubscribe, cancellationToken),
+                                (secondPropertyValue, state2) =>
+                                    secondPropertyValue is not null
+                                        ? new ObservePropertyChanged<TProperty2, TProperty3>(secondPropertyValue,
+                                            state2.propertySelector3, state2.property3Name, state2.pushCurrentValueOnSubscribe,
+                                            state2.cancellationToken)
+                                        : Empty<TProperty3>())
+                            .Switch()
+                        : Empty<TProperty3>())
+            .Switch();
+    }
 
     /// <summary>
     /// Convert INotifyPropertyChanging to Observable.
@@ -67,11 +112,95 @@ public static Observable<TProperty> ObservePropertyChanging<T, TProperty>(this T
         if (expr == null) throw new ArgumentNullException(expr);
 
         var propertyName = expr!.Substring(expr.LastIndexOf('.') + 1);
-        return new ObservePropertyChanging<T, TProperty>(value, propertySelector, propertyName, pushCurrentValueOnSubscribe, cancellationToken);
+        return new ObservePropertyChanging<T, TProperty>(value, propertySelector, propertyName,
+            pushCurrentValueOnSubscribe, cancellationToken);
+    }
+
+    /// <summary>
+    /// Convert INotifyPropertyChanging to Observable.
+    /// `propertySelector1` and `propertySelector2` must be a Func specifying a simple property. For example, it extracts "Foo" from `x => x.Foo`.
+    /// </summary>
+    public static Observable<TProperty2> ObservePropertyChanging<T, TProperty1, TProperty2>(this T value,
+        Func<T, TProperty1> propertySelector1,
+        Func<TProperty1, TProperty2> propertySelector2,
+        bool pushCurrentValueOnSubscribe = true,
+        CancellationToken cancellationToken = default,
+        [CallerArgumentExpression(nameof(propertySelector1))] string? propertySelector1Expr = null,
+        [CallerArgumentExpression(nameof(propertySelector2))] string? propertySelector2Expr = null)
+        where T : INotifyPropertyChanged
+        where TProperty1 : INotifyPropertyChanging
+    {
+        if (propertySelector1Expr == null) throw new ArgumentNullException(propertySelector1Expr);
+        if (propertySelector2Expr == null) throw new ArgumentNullException(propertySelector2Expr);
+
+        var property1Name = propertySelector1Expr!.Substring(propertySelector1Expr.LastIndexOf('.') + 1);
+        var property2Name = propertySelector2Expr!.Substring(propertySelector2Expr.LastIndexOf('.') + 1);
+
+
+        return new ObservePropertyChanged<T, TProperty1>(value, propertySelector1, property1Name, true, cancellationToken)
+            .Select(
+                (propertySelector2, property2Name, pushCurrentValueOnSubscribe, cancellationToken),
+                (firstPropertyValue, state) =>
+                    firstPropertyValue is not null
+                        ? new ObservePropertyChanging<TProperty1, TProperty2>(firstPropertyValue,
+                            state.propertySelector2, state.property2Name, state.pushCurrentValueOnSubscribe,
+                            state.cancellationToken)
+                        : Empty<TProperty2>())
+            .Switch();
+    }
+
+    /// <summary>
+    /// Convert INotifyPropertyChanging to Observable.
+    /// `propertySelector1`, `propertySelector2`, and `propertySelector3` must be a Func specifying a simple property. For example, it extracts "Foo" from `x => x.Foo`.
+    /// </summary>
+    public static Observable<TProperty3> ObservePropertyChanging<T, TProperty1, TProperty2, TProperty3>(this T value,
+        Func<T, TProperty1> propertySelector1,
+        Func<TProperty1, TProperty2> propertySelector2,
+        Func<TProperty2, TProperty3> propertySelector3,
+        bool pushCurrentValueOnSubscribe = true,
+        CancellationToken cancellationToken = default,
+        [CallerArgumentExpression(nameof(propertySelector1))] string? propertySelector1Expr = null,
+        [CallerArgumentExpression(nameof(propertySelector2))] string? propertySelector2Expr = null,
+        [CallerArgumentExpression(nameof(propertySelector3))] string? propertySelector3Expr = null)
+        where T : INotifyPropertyChanged
+        where TProperty1 : INotifyPropertyChanged
+        where TProperty2 : INotifyPropertyChanging
+    {
+        if (propertySelector1Expr == null) throw new ArgumentNullException(propertySelector1Expr);
+        if (propertySelector2Expr == null) throw new ArgumentNullException(propertySelector2Expr);
+        if (propertySelector3Expr == null) throw new ArgumentNullException(propertySelector3Expr);
+
+        var property1Name = propertySelector1Expr!.Substring(propertySelector1Expr.LastIndexOf('.') + 1);
+        var property2Name = propertySelector2Expr!.Substring(propertySelector2Expr.LastIndexOf('.') + 1);
+        var property3Name = propertySelector3Expr!.Substring(propertySelector3Expr.LastIndexOf('.') + 1);
+
+        return new ObservePropertyChanged<T, TProperty1>(value, propertySelector1, property1Name, pushCurrentValueOnSubscribe, cancellationToken)
+            .Select(
+                (propertySelector2, property2Name, propertySelector3, property3Name, pushCurrentValueOnSubscribe, cancellationToken),
+                (firstPropertyValue, state) =>
+                    (firstPropertyValue is not null
+                        ? new ObservePropertyChanged<TProperty1, TProperty2>(
+                                firstPropertyValue, state.propertySelector2, state.property2Name, true, state.cancellationToken)
+                            .Select(
+                                (state.propertySelector3, state.property3Name, pushCurrentValueOnSubscribe, cancellationToken),
+                                (secondPropertyValue, state2) =>
+                                    secondPropertyValue is not null
+                                        ? new ObservePropertyChanging<TProperty2, TProperty3>(secondPropertyValue,
+                                            state2.propertySelector3, state2.property3Name, state2.pushCurrentValueOnSubscribe,
+                                            state2.cancellationToken)
+                                        : Empty<TProperty3>())
+                            .Switch()
+                        : Empty<TProperty3>()))
+            .Switch();
     }
 }
 
-internal sealed class ObservePropertyChanged<T, TProperty>(T value, Func<T, TProperty> propertySelector, string propertyName, bool pushCurrentValueOnSubscribe, CancellationToken cancellationToken)
+internal sealed class ObservePropertyChanged<T, TProperty>(
+    T value,
+    Func<T, TProperty> propertySelector,
+    string propertyName,
+    bool pushCurrentValueOnSubscribe,
+    CancellationToken cancellationToken)
     : Observable<TProperty> where T : INotifyPropertyChanged
 {
     protected override IDisposable SubscribeCore(Observer<TProperty> observer)
@@ -150,7 +279,12 @@ public void Dispose()
     }
 }
 
-internal sealed class ObservePropertyChanging<T, TProperty>(T value, Func<T, TProperty> propertySelector, string propertyName, bool pushCurrentValueOnSubscribe, CancellationToken cancellationToken)
+internal sealed class ObservePropertyChanging<T, TProperty>(
+    T value,
+    Func<T, TProperty> propertySelector,
+    string propertyName,
+    bool pushCurrentValueOnSubscribe,
+    CancellationToken cancellationToken)
     : Observable<TProperty> where T : INotifyPropertyChanging
 {
     protected override IDisposable SubscribeCore(Observer<TProperty> observer)
@@ -160,10 +294,10 @@ protected override IDisposable SubscribeCore(Observer<TProperty> observer)
             observer.OnNext(propertySelector(value));
         }
 
-        return new _ObservePropertyChanged(observer, value, propertySelector, propertyName, cancellationToken);
+        return new _ObservePropertyChanging(observer, value, propertySelector, propertyName, cancellationToken);
     }
 
-    sealed class _ObservePropertyChanged : IDisposable
+    sealed class _ObservePropertyChanging : IDisposable
     {
         readonly Observer<TProperty> observer;
         readonly T value;
@@ -172,7 +306,7 @@ sealed class _ObservePropertyChanged : IDisposable
         PropertyChangingEventHandler? eventHandler;
         CancellationTokenRegistration cancellationTokenRegistration;
 
-        public _ObservePropertyChanged(Observer<TProperty> observer, T value, Func<T, TProperty> propertySelector, string propertyName, CancellationToken cancellationToken)
+        public _ObservePropertyChanging(Observer<TProperty> observer, T value, Func<T, TProperty> propertySelector, string propertyName, CancellationToken cancellationToken)
         {
             this.observer = observer;
             this.value = value;
@@ -186,7 +320,7 @@ public _ObservePropertyChanged(Observer<TProperty> observer, T value, Func<T, TP
             {
                 this.cancellationTokenRegistration = cancellationToken.UnsafeRegister(static state =>
                 {
-                    var s = (_ObservePropertyChanged)state!;
+                    var s = (_ObservePropertyChanging)state!;
                     s.CompleteDispose();
                 }, this);
             }

diff --git a/tests/R3.Tests/FactoryTests/ObservePropertyTest.cs b/tests/R3.Tests/FactoryTests/ObservePropertyTest.cs
@@ -39,6 +39,34 @@ public void NestedPropertyChanged()
         propertyChanger.InnerPropertyChanged.Value = 1;
 
         liveList.AssertEqual([0, 1]);
+
+        propertyChanger.InnerPropertyChanged.Value = 2;
+
+        liveList.AssertEqual([0, 1, 2]);
+    }
+
+    [Fact]
+    public void DoubleNestedPropertyChanged()
+    {
+        ChangesProperty propertyChanger = new();
+
+        using var liveList = propertyChanger
+            .ObservePropertyChanged(x => x.InnerPropertyChanged, x => x.InnerPropertyChanged, x => x.Value)
+            .ToLiveList();
+
+        liveList.AssertEqual([]);
+
+        propertyChanger.InnerPropertyChanged = new();
+
+        liveList.AssertEqual([]);
+
+        propertyChanger.InnerPropertyChanged.InnerPropertyChanged = new();
+
+        liveList.AssertEqual([0]);
+
+        propertyChanger.InnerPropertyChanged.InnerPropertyChanged.Value = 1;
+
+        liveList.AssertEqual([0, 1]);
     }
 
     [Fact]
@@ -57,6 +85,58 @@ public void PropertyChanging()
         liveList.AssertEqual([0, 0]);
     }
 
+    [Fact]
+    public void NestedPropertyChanging()
+    {
+        ChangesProperty propertyChanger = new();
+
+        using var liveList = propertyChanger
+            .ObservePropertyChanging(x => x.InnerPropertyChanged, x => x.Value)
+            .ToLiveList();
+
+        liveList.AssertEqual([]);
+
+        propertyChanger.InnerPropertyChanged = new();
+
+        liveList.AssertEqual([0]);
+
+        propertyChanger.InnerPropertyChanged.Value = 1;
+
+        liveList.AssertEqual([0, 0]);
+
+        propertyChanger.InnerPropertyChanged.Value = 2;
+
+        liveList.AssertEqual([0, 0, 1]);
+    }
+
+    [Fact]
+    public void DoubleNestedPropertyChanging()
+    {
+        ChangesProperty propertyChanger = new();
+
+        using var liveList = propertyChanger
+            .ObservePropertyChanging(x => x.InnerPropertyChanged, x => x.InnerPropertyChanged, x => x.Value)
+            .ToLiveList();
+
+        liveList.AssertEqual([]);
+
+        propertyChanger.InnerPropertyChanged = new();
+
+        liveList.AssertEqual([]);
+
+        propertyChanger.InnerPropertyChanged.InnerPropertyChanged = new();
+
+        liveList.AssertEqual([0]);
+
+        propertyChanger.InnerPropertyChanged.InnerPropertyChanged.Value = 1;
+
+        liveList.AssertEqual([0, 0]);
+
+        propertyChanger.InnerPropertyChanged.InnerPropertyChanged.Value = 2;
+
+        liveList.AssertEqual([0, 0, 1]);
+    }
+
     class ChangesProperty : INotifyPropertyChanged, INotifyPropertyChanging
     {
         private int _value;