fix(combobox): fix binding to an old DataSource when both ItemsSource and SelectedItem are bound

Author: ramezgerges

src/Uno.Foundation/Uno.Core.Extensions/Uno.Core.Extensions.Compatibility/Collections/ImmutableList.cs

@@ -112,6 +112,13 @@ public int LastIndexOf(T item, int index, int count, IEqualityComparer<T> equali
 			return -1;
 		}
 
+		/// <inheritdoc />
+		[Pure]
+		IImmutableList<T> IImmutableList<T>.Insert(int index, T element)
+		{
+			return Insert(index, element);
+		}
+
 		/// <inheritdoc />
 		[Pure]
 		IImmutableList<T> IImmutableList<T>.Add(T value)
@@ -132,7 +139,7 @@ public IImmutableList<T> AddRange(IEnumerable<T> items)
 
 		/// <inheritdoc />
 		[Pure]
-		public IImmutableList<T> Insert(int index, T element)
+		public ImmutableList<T> Insert(int index, T element)
 		{
 			var newData = new T[_data.Length + 1];
 			newData[index] = element; // will throw out-of-range exception if index is not valid
@@ -141,7 +148,7 @@ public IImmutableList<T> Insert(int index, T element)
 			{
 				Array.Copy(_data, newData, index);
 			}
-			if (index + 1 < _data.Length)
+			if (index < _data.Length)
 			{
 				Array.Copy(_data, index, newData, index + 1, _data.Length - index);
 			}

src/Uno.UI/UI/Xaml/Controls/Primitives/Selector.cs

@@ -83,7 +83,8 @@ protected override void OnApplyTemplate()
 			"SelectedItem",
 			typeof(object),
 			typeof(Selector),
-			new FrameworkPropertyMetadata(defaultValue: null)
+			new FrameworkPropertyMetadata(defaultValue: null),
+			new List<DependencyProperty> { ItemsControl.ItemsSourceProperty }
 		);
 
 		public object SelectedItem

src/Uno.UI/UI/Xaml/DependencyProperty.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using System.Text;
 using Windows.UI.Xaml;
@@ -51,7 +52,7 @@ public sealed partial class DependencyProperty
 
 		private static int _globalId;
 
-		private DependencyProperty(string name, Type propertyType, Type ownerType, PropertyMetadata defaultMetadata, bool attached)
+		private DependencyProperty(string name, Type propertyType, Type ownerType, PropertyMetadata defaultMetadata, bool attached, IEnumerable<DependencyProperty> dependentProperties)
 		{
 			_name = name;
 			_propertyType = propertyType;
@@ -70,6 +71,13 @@ private DependencyProperty(string name, Type propertyType, Type ownerType, Prope
 
 			// Improve the performance of the hash code by
 			CachedHashCode = _name.GetHashCode() ^ ownerType.GetHashCode();
+
+			DependentProperties = dependentProperties.ToImmutableArray();
+		}
+
+		private DependencyProperty(string name, Type propertyType, Type ownerType, PropertyMetadata defaultMetadata, bool attached):
+			this(name, propertyType, ownerType, defaultMetadata, attached, Enumerable.Empty<DependencyProperty>())
+		{
 		}
 
 		/// <summary>
@@ -95,12 +103,13 @@ internal bool IsDependencyObjectCollection
 		/// <param name="name">The name of the property.</param>
 		/// <param name="propertyType">The type of the property</param>
 		/// <param name="ownerType">The owner type of the property</param>
-		/// <param name="typeMetadata">The metadata to use when creating the property</param>
+		/// <param name="defaultMetadata">The metadata to use when creating the property</param>
+		/// <param name="dependentProperties">Other properties whose bindings need to update before the new property's bindings</param>
 		/// <returns>A dependency property instance</returns>
 		/// <exception cref="InvalidOperationException">A property with the same name has already been declared for the ownerType</exception>
-		public static DependencyProperty Register(string name, Type propertyType, Type ownerType, PropertyMetadata typeMetadata)
+		internal static DependencyProperty Register(string name, Type propertyType, Type ownerType, PropertyMetadata defaultMetadata, IEnumerable<DependencyProperty> dependentProperties)
 		{
-			var newProperty = new DependencyProperty(name, propertyType, ownerType, typeMetadata, attached: false);
+			var newProperty = new DependencyProperty(name, propertyType, ownerType, defaultMetadata, attached: true, dependentProperties);
 
 			try
 			{
@@ -117,6 +126,18 @@ public static DependencyProperty Register(string name, Type propertyType, Type o
 			return newProperty;
 		}
 
+		/// <summary>
+		/// Registers a dependency property on the specified <paramref name="ownerType"/>.
+		/// </summary>
+		/// <param name="name">The name of the property.</param>
+		/// <param name="propertyType">The type of the property</param>
+		/// <param name="ownerType">The owner type of the property</param>
+		/// <param name="typeMetadata">The metadata to use when creating the property</param>
+		/// <returns>A dependency property instance</returns>
+		/// <exception cref="InvalidOperationException">A property with the same name has already been declared for the ownerType</exception>
+		public static DependencyProperty Register(string name, Type propertyType, Type ownerType, PropertyMetadata typeMetadata)
+			=> Register(name, propertyType, ownerType, typeMetadata, Enumerable.Empty<DependencyProperty>());
+
 		/// <summary>
 		/// Registers a dependency property on the specified <paramref name="ownerType"/>.
 		/// </summary>
@@ -191,6 +212,8 @@ internal int CachedHashCode
 			get;
 		}
 
+		internal ImmutableArray<DependencyProperty> DependentProperties { get; } = ImmutableArray<DependencyProperty>.Empty;
+
 		/// <summary>
 		/// Specifies a static value that is used by the dependency property system rather than null to indicate that
 		/// the property exists, but does not have its value set by the dependency property system.

src/Uno.UI/UI/Xaml/DependencyPropertyDetailsCollection.Bindings.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Text;
 using Uno.Collections;
 using Uno.Extensions;
@@ -41,6 +42,7 @@ internal void ApplyTemplatedParent(FrameworkElement templatedParent)
 		/// </summary>
 		public void ApplyDataContext(object dataContext)
 		{
+			_bindings = new (_bindings.OrderBy(x => x, new BindingExpressionComparer()));
 			var bindings = _bindings.Data;
 
 			for (int i = 0; i < bindings.Length; i++)
@@ -146,7 +148,12 @@ internal void SetBinding(DependencyProperty dependencyProperty, Binding binding,
 				}
 				else
 				{
-					_bindings = _bindings.Add(bindingExpression);
+					var index = Array.BinarySearch(_bindings.Data, bindingExpression, new BindingExpressionComparer());
+					if (index < 0)
+					{
+						index = ~index;
+					}
+					_bindings = _bindings.Insert(index, bindingExpression);
 
 					if (bindingExpression.TargetPropertyDetails.Property.UniqueId == DataContextPropertyDetails.Property.UniqueId)
 					{
@@ -219,5 +226,27 @@ internal BindingExpression GetBindingExpression(DependencyProperty dependencyPro
 
 			return null;
 		}
+
+		class BindingExpressionComparer : IComparer<BindingExpression>
+		{
+			public int Compare(BindingExpression expression1, BindingExpression expression2)
+			{
+				var property1 = expression1.TargetPropertyDetails.Property;
+				var property2 = expression2.TargetPropertyDetails.Property;
+
+				if (property1.DependentProperties.Contains(property2))
+				{
+					return -1;
+				}
+
+				if (property2.DependentProperties.Contains(property1))
+				{
+					return 1;
+				}
+
+				// make sure we define a total order
+				return string.Compare(property1.ToString(), property2.ToString(), StringComparison.OrdinalIgnoreCase);
+			}
+		}
 	}
 }