Merge branch 'master' into fixes/RightToLeftTextRendering

src/Avalonia.Base/Data/Core/Plugins/InpcPropertyAccessorPlugin.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.ComponentModel;
 using System.Reflection;
 using Avalonia.Utilities;
@@ -11,8 +12,11 @@ namespace Avalonia.Data.Core.Plugins
     /// </summary>
     public class InpcPropertyAccessorPlugin : IPropertyAccessorPlugin
     {
+        private readonly Dictionary<(Type, string), PropertyInfo> _propertyLookup =
+            new Dictionary<(Type, string), PropertyInfo>();
+        
         /// <inheritdoc/>
-        public bool Match(object obj, string propertyName) => GetPropertyWithName(obj.GetType(), propertyName) != null;
+        public bool Match(object obj, string propertyName) => GetFirstPropertyWithName(obj.GetType(), propertyName) != null;
 
         /// <summary>
         /// Starts monitoring the value of a property on an object.
@@ -30,7 +34,7 @@ namespace Avalonia.Data.Core.Plugins
 
             reference.TryGetTarget(out object instance);
 
-            var p = GetPropertyWithName(instance.GetType(), propertyName);
+            var p = GetFirstPropertyWithName(instance.GetType(), propertyName);
 
             if (p != null)
             {
@@ -44,12 +48,40 @@ namespace Avalonia.Data.Core.Plugins
             }
         }
 
-        private static PropertyInfo GetPropertyWithName(Type type, string propertyName)
+        private PropertyInfo GetFirstPropertyWithName(Type type, string propertyName)
         {
-            const BindingFlags bindingFlags = BindingFlags.NonPublic | BindingFlags.Public |
-                                              BindingFlags.Static | BindingFlags.Instance;
+            var key = (type, propertyName);
+            
+            if (!_propertyLookup.TryGetValue(key, out PropertyInfo propertyInfo))
+            {
+                propertyInfo = TryFindAndCacheProperty(type, propertyName);
+            }
+
+            return propertyInfo;
+        }
+        
+        private PropertyInfo TryFindAndCacheProperty(Type type, string propertyName)
+        {
+            PropertyInfo found = null;
+
+            const BindingFlags bindingFlags =
+                BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static | BindingFlags.Instance;
+
+            var properties = type.GetProperties(bindingFlags);
+
+            foreach (PropertyInfo propertyInfo in properties)
+            {
+                if (propertyInfo.Name == propertyName)
+                {
+                    found = propertyInfo;
+
+                    break;
+                }
+            }
+
+            _propertyLookup.Add((type, propertyName), found);
 
-            return type.GetProperty(propertyName, bindingFlags);
+            return found;
         }
 
         private class Accessor : PropertyAccessorBase, IWeakSubscriber<PropertyChangedEventArgs>

src/Avalonia.Controls/TreeView.cs

@@ -117,10 +117,8 @@ namespace Avalonia.Controls
                 if (value != null)
                 {
                     if (selectedItems.Count != 1 || selectedItems[0] != value)
-                    {
-                        _syncingSelectedItems = true;
-                        SelectSingleItem(value);
-                        _syncingSelectedItems = false;
+                    {                        
+                        SelectSingleItem(value);                        
                     }
                 }
                 else if (SelectedItems.Count > 0)
@@ -219,8 +217,12 @@ namespace Avalonia.Controls
 
         private void SelectSingleItem(object item)
         {
-            SelectedItems.Clear();
+            _syncingSelectedItems = true;
+            SelectedItems.Clear();            
             SelectedItems.Add(item);
+            _syncingSelectedItems = false;
+
+            SetAndRaise(SelectedItemProperty, ref _selectedItem, item);            
         }
 
         /// <summary>

tests/Avalonia.Base.UnitTests/Data/Core/ExpressionObserverTests_Property.cs

@@ -600,6 +600,24 @@ namespace Avalonia.Base.UnitTests.Data.Core
                 result);
         }
 
+        [Fact]
+        public void Should_Not_Throw_Exception_On_Duplicate_Properties()
+        {
+            // Repro of https://github.com/AvaloniaUI/Avalonia/issues/4733.
+            var source = new MyViewModel();
+            var target = new PropertyAccessorNode("Name", false);
+            
+            target.Target = new WeakReference<object>(source);
+            
+            var result = new List<object>();
+            
+            target.Subscribe(x => result.Add(x));
+        }
+        
+        public class MyViewModelBase { public object Name => "Name"; }
+        
+        public class MyViewModel : MyViewModelBase { public new string Name => "NewName"; }
+
         private interface INext
         {
             int PropertyChangedSubscriptionCount { get; }

tests/Avalonia.Controls.UnitTests/TreeViewTests.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using Avalonia.Collections;
 using Avalonia.Controls.Presenters;
@@ -13,6 +14,7 @@ using Avalonia.Interactivity;
 using Avalonia.LogicalTree;
 using Avalonia.Styling;
 using Avalonia.UnitTests;
+using ReactiveUI;
 using Xunit;
 
 namespace Avalonia.Controls.UnitTests
@@ -454,6 +456,41 @@ namespace Avalonia.Controls.UnitTests
             }
         }
 
+        [Fact]
+        public void Bound_SelectedItem_Should_Not_Be_Cleared_when_Changing_Selection()
+        {
+            using (Application())
+            {
+                var dataContext = new TestDataContext();
+
+                var target = new TreeView
+                {
+                    Template = CreateTreeViewTemplate(),
+                    DataContext = dataContext
+                };
+
+                target.Bind(TreeView.ItemsProperty, new Binding("Items"));
+                target.Bind(TreeView.SelectedItemProperty, new Binding("SelectedItem"));
+
+                var visualRoot = new TestRoot();
+                visualRoot.Child = target;
+
+                CreateNodeDataTemplate(target);
+                ApplyTemplates(target);
+
+                var selectedValues = new List<object>();
+
+                dataContext.WhenAnyValue(x => x.SelectedItem)
+                    .Subscribe(x => selectedValues.Add(x));
+
+                _mouse.Click((Interactive)target.Presenter.Panel.Children[0], MouseButton.Left);
+                _mouse.Click((Interactive)target.Presenter.Panel.Children[2], MouseButton.Left);
+
+                Assert.Equal(3, selectedValues.Count);
+                Assert.Equal(new[] { null, "Item 0", "Item 2" }, selectedValues.ToArray());
+            }
+        }
+
         [Fact]
         public void LogicalChildren_Should_Be_Set()
         {
@@ -1288,5 +1325,26 @@ namespace Avalonia.Controls.UnitTests
         private class DerivedTreeView : TreeView
         {
         }
+
+        private class TestDataContext : ReactiveObject
+        {
+            private string _selectedItem;
+
+            public TestDataContext()
+            {
+                Items = new ObservableCollection<string>(Enumerable.Range(0, 5).Select(i => $"Item {i}"));
+            }
+
+            public ObservableCollection<string> Items { get; }
+
+            public string SelectedItem
+            {
+                get { return _selectedItem; }
+                set
+                {
+                    this.RaiseAndSetIfChanged(ref _selectedItem, value);
+                }
+            }
+        }
     }
 }