Merge pull request #537 from donandren/memberselectorpath

member selector support complex member path

src/Markup/Avalonia.Markup.Xaml/Templates/MemberSelector.cs

@@ -1,20 +1,64 @@
-// Copyright (c) The Avalonia Project. All rights reserved.
+// Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
-using System.Reflection;
 using Avalonia.Controls.Templates;
+using Avalonia.Data;
+using Avalonia.Markup.Data;
+using System;
 
 namespace Avalonia.Markup.Xaml.Templates
 {
     public class MemberSelector : IMemberSelector
     {
-        public string MemberName { get; set; }
+        public string MemberName
+        {
+            get { return _memberName; }
+            set
+            {
+                if (_memberName != value)
+                {
+                    _memberName = value;
+                    _expressionNode = null;
+                    _memberValueNode = null;
+                }
+            }
+        }
 
         public object Select(object o)
         {
-            // TODO: Handle nested property paths, changing values etc.
-            var property = o.GetType().GetRuntimeProperty(MemberName);
-            return property?.GetValue(o);
+            if (string.IsNullOrEmpty(MemberName))
+            {
+                return o;
+            }
+
+            if (_expressionNode == null)
+            {
+                _expressionNode = ExpressionNodeBuilder.Build(MemberName);
+
+                _memberValueNode = _expressionNode;
+
+                while (_memberValueNode.Next != null)
+                    _memberValueNode = _memberValueNode.Next;
+            }
+
+            _expressionNode.Target = new WeakReference(o);
+
+            object result = _memberValueNode.CurrentValue.Target;
+
+            if (result == AvaloniaProperty.UnsetValue)
+            {
+                return null;
+            }
+            else if (result is BindingError)
+            {
+                return null;
+            }
+
+            return result;
         }
+
+        private ExpressionNode _expressionNode;
+        private string _memberName;
+        private ExpressionNode _memberValueNode;
     }
-}
+}

src/Markup/Avalonia.Markup/Properties/AssemblyInfo.cs

@@ -7,4 +7,5 @@ using System.Runtime.CompilerServices;
 
 [assembly: AssemblyTitle("Avalonia.Markup")]
 [assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Markup")]
-[assembly: InternalsVisibleTo("Avalonia.Markup.UnitTests")]
+[assembly: InternalsVisibleTo("Avalonia.Markup.UnitTests")]
+[assembly: InternalsVisibleTo("Avalonia.Markup.Xaml")]

tests/Avalonia.Markup.Xaml.UnitTests/Avalonia.Markup.Xaml.UnitTests.csproj

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="..\..\packages\xunit.runner.visualstudio.2.1.0\build\net20\xunit.runner.visualstudio.props" Condition="Exists('..\..\packages\xunit.runner.visualstudio.2.1.0\build\net20\xunit.runner.visualstudio.props')" />
   <PropertyGroup>
@@ -103,6 +103,7 @@
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="SampleAvaloniaObject.cs" />
     <Compile Include="StyleTests.cs" />
+    <Compile Include="Templates\MemberSelectorTests.cs" />
     <Compile Include="Templates\DataTemplateTests.cs" />
     <Compile Include="Xaml\BasicTests.cs" />
     <Compile Include="Xaml\ControlBindingTests.cs" />

tests/Avalonia.Markup.Xaml.UnitTests/Templates/MemberSelectorTests.cs

@@ -0,0 +1,168 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using Avalonia.Markup.Xaml.Templates;
+using System;
+using Xunit;
+
+namespace Avalonia.Markup.Xaml.UnitTests.Templates
+{
+    public class MemberSelectorTests
+    {
+        [Fact]
+        public void Should_Not_Hold_Reference_To_Object()
+        {
+            WeakReference dataRef = null;
+
+            var selector = new MemberSelector() { MemberName = "Child.StringValue" };
+
+            Action run = () =>
+            {
+                var data = new Item()
+                {
+                    Child = new Item() { StringValue = "Value1" }
+                };
+
+                Assert.Same("Value1", selector.Select(data));
+
+                dataRef = new WeakReference(data);
+            };
+
+            run();
+
+            GC.Collect();
+
+            Assert.False(dataRef.IsAlive);
+        }
+
+        [Fact]
+        public void Should_Select_Child_Property_Value()
+        {
+            var selector = new MemberSelector() { MemberName = "Child.StringValue" };
+
+            var data = new Item()
+            {
+                Child = new Item() { StringValue = "Value1" }
+            };
+
+            Assert.Same("Value1", selector.Select(data));
+        }
+
+        [Fact]
+        public void Should_Select_Child_Property_Value_In_Multiple_Items()
+        {
+            var selector = new MemberSelector() { MemberName = "Child.StringValue" };
+
+            var data = new Item[]
+            {
+                new Item() { Child = new Item() { StringValue = "Value1" } },
+                new Item() { Child = new Item() { StringValue = "Value2" } },
+                new Item() { Child = new Item() { StringValue = "Value3" } }
+            };
+
+            Assert.Same("Value1", selector.Select(data[0]));
+            Assert.Same("Value2", selector.Select(data[1]));
+            Assert.Same("Value3", selector.Select(data[2]));
+        }
+
+        [Fact]
+        public void Should_Select_MoreComplex_Property_Value()
+        {
+            var selector = new MemberSelector() { MemberName = "Child.Child.Child.StringValue" };
+
+            var data = new Item()
+            {
+                Child = new Item()
+                {
+                    Child = new Item()
+                    {
+                        Child = new Item() { StringValue = "Value1" }
+                    }
+                }
+            };
+
+            Assert.Same("Value1", selector.Select(data));
+        }
+
+        [Fact]
+        public void Should_Select_Null_Value_On_Null_Object()
+        {
+            var selector = new MemberSelector() { MemberName = "StringValue" };
+
+            Assert.Equal(null, selector.Select(null));
+        }
+
+        [Fact]
+        public void Should_Select_Null_Value_On_Wrong_MemberName()
+        {
+            var selector = new MemberSelector() { MemberName = "WrongProperty" };
+
+            var data = new Item() { StringValue = "Value1" };
+
+            Assert.Same(null, selector.Select(data));
+        }
+
+        [Fact]
+        public void Should_Select_Simple_Property_Value()
+        {
+            var selector = new MemberSelector() { MemberName = "StringValue" };
+
+            var data = new Item() { StringValue = "Value1" };
+
+            Assert.Same("Value1", selector.Select(data));
+        }
+
+        [Fact]
+        public void Should_Select_Simple_Property_Value_In_Multiple_Items()
+        {
+            var selector = new MemberSelector() { MemberName = "StringValue" };
+
+            var data = new Item[]
+            {
+                new Item() { StringValue = "Value1" },
+                new Item() { StringValue = "Value2" },
+                new Item() { StringValue = "Value3" }
+            };
+
+            Assert.Same("Value1", selector.Select(data[0]));
+            Assert.Same("Value2", selector.Select(data[1]));
+            Assert.Same("Value3", selector.Select(data[2]));
+        }
+
+        [Fact]
+        public void Should_Select_Target_On_Empty_MemberName()
+        {
+            var selector = new MemberSelector();
+
+            var data = new Item() { StringValue = "Value1" };
+
+            Assert.Same(data, selector.Select(data));
+        }
+
+        [Fact]
+        public void Should_Support_Change_Of_MemberName()
+        {
+            var selector = new MemberSelector() { MemberName = "StringValue" };
+
+            var data = new Item()
+            {
+                StringValue = "Value1",
+                IntValue = 1
+            };
+
+            Assert.Same("Value1", selector.Select(data));
+
+            selector.MemberName = "IntValue";
+
+            Assert.Equal(1, selector.Select(data));
+        }
+
+        private class Item
+        {
+            public Item Child { get; set; }
+            public int IntValue { get; set; }
+
+            public string StringValue { get; set; }
+        }
+    }
+}