feat: x:Shared (#16644)

* feat: x:Shared

* test: Add x:Shared test

* fix: Address review

* fix: Address review

* fix: Address review

src/Avalonia.Base/Controls/ResourceDictionary.cs

@@ -147,6 +147,9 @@ namespace Avalonia.Controls
         public void AddDeferred(object key, IDeferredContent deferredContent)
             => Add(key, deferredContent);
 
+        public void AddNotSharedDeferred(object key, IDeferredContent deferredContent)
+            => Add(key, new NotSharedDeferredItem(deferredContent));
+
         public void Clear()
         {
             if (_inner?.Count > 0)
@@ -236,12 +239,16 @@ namespace Avalonia.Controls
                     try
                     {
                         _lastDeferredItemKey = key;
-                        _inner[key] = value = deferred.Build(null) switch
+                        value = deferred.Build(null) switch
                         {
                             ITemplateResult t => t.Result,
                             { } v => v,
                             _ => null,
                         };
+                        if (deferred is not NotSharedDeferredItem)
+                        {
+                            _inner[key] = value;
+                        }
                     }
                     finally
                     {
@@ -250,7 +257,6 @@ namespace Avalonia.Controls
                 }
                 return true;
             }
-
             value = null;
             return false;
         }
@@ -376,5 +382,11 @@ namespace Avalonia.Controls
             public DeferredItem(Func<IServiceProvider?, object?> factory) => _factory = factory;
             public object? Build(IServiceProvider? serviceProvider) => _factory(serviceProvider);
         }
+
+        private sealed class NotSharedDeferredItem(IDeferredContent deferredContent) : IDeferredContent
+        {
+            private readonly IDeferredContent _deferredContent = deferredContent ;
+            public object? Build(IServiceProvider? serviceProvider) => _deferredContent.Build(serviceProvider);
+        }
     }
 }

src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlDeferredResourceTransformer.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Visitors;
+using XamlX;
 using XamlX.Ast;
 using XamlX.Emit;
 using XamlX.IL;
@@ -22,23 +23,61 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
             if (pa.Property.DeclaringType == types.ResourceDictionary && pa.Property.Name == "Content"
                 && ShouldBeDeferred(pa.Values[1]))
             {
+                IXamlMethod addMethod = TryGetSharedValue(pa.Values[1], out var isShared) && !isShared
+                    ? types.ResourceDictionaryNotSharedDeferredAdd
+                    : types.ResourceDictionaryDeferredAdd;
+
                 pa.Values[1] = new XamlDeferredContentNode(pa.Values[1], types.XamlIlTypes.Object, context.Configuration);
                 pa.PossibleSetters = new List<IXamlPropertySetter>
                 {
-                    new XamlDirectCallPropertySetter(types.ResourceDictionaryDeferredAdd),
+                    new XamlDirectCallPropertySetter(addMethod),
                 };
             }
             else if (pa.Property.Name == "Resources" && pa.Property.Getter?.ReturnType.Equals(types.IResourceDictionary) == true
                 && ShouldBeDeferred(pa.Values[1]))
             {
+                IXamlMethod addMethod = TryGetSharedValue(pa.Values[1], out var isShared) && !isShared
+                    ? types.ResourceDictionaryNotSharedDeferredAdd
+                    : types.ResourceDictionaryDeferredAdd;
+
                 pa.Values[1] = new XamlDeferredContentNode(pa.Values[1], types.XamlIlTypes.Object, context.Configuration);
                 pa.PossibleSetters = new List<IXamlPropertySetter>
                 {
-                    new AdderSetter(pa.Property.Getter, types.ResourceDictionaryDeferredAdd),
+                    new AdderSetter(pa.Property.Getter, addMethod),
                 };
             }
 
             return node;
+
+            bool TryGetSharedValue(IXamlAstValueNode valueNode, out bool value)
+            {
+                value = default;
+                if (valueNode is XamlAstConstructableObjectNode co)
+                {
+                    // Try find x:Share directive
+                    if (co.Children.Find(d => d is XamlAstXmlDirective { Namespace: XamlNamespaces.Xaml2006, Name: "Shared" }) is XamlAstXmlDirective sharedDirective)
+                    {
+                        if (sharedDirective.Values.Count == 1 && sharedDirective.Values[0] is XamlAstTextNode text)
+                        {
+                            if (bool.TryParse(text.Text, out var parseValue))
+                            {
+                                // If the parser succeeds, remove the x:Share directive
+                                co.Children.Remove(sharedDirective);
+                                return true;
+                            }
+                            else
+                            {
+                                context.ReportTransformError("Invalid argument type for x:Shared directive.", node);
+                            }
+                        }
+                        else
+                        {
+                            context.ReportTransformError("Invalid number of arguments for x:Shared directive.", node);
+                        }
+                    }
+                }
+                return false;
+            }
         }
 
         private static bool ShouldBeDeferred(IXamlAstValueNode node)
@@ -71,7 +110,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
 
             return true;
         }
-        
+
         class AdderSetter : IXamlILOptimizedEmitablePropertySetter, IEquatable<AdderSetter>
         {
             private readonly IXamlMethod _getter;

src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/Transformers/AvaloniaXamlIlWellKnownTypes.cs

@@ -118,6 +118,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
         public IXamlType IResourceDictionary { get; }
         public IXamlType ResourceDictionary { get; }
         public IXamlMethod ResourceDictionaryDeferredAdd { get; }
+        public IXamlMethod ResourceDictionaryNotSharedDeferredAdd { get; }
         public IXamlMethod ResourceDictionaryEnsureCapacity { get; }
         public IXamlMethod ResourceDictionaryGetCount { get; }
         public IXamlType IThemeVariantProvider { get; }
@@ -312,6 +313,9 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
             ResourceDictionary = cfg.TypeSystem.GetType("Avalonia.Controls.ResourceDictionary");
             ResourceDictionaryDeferredAdd = ResourceDictionary.GetMethod("AddDeferred", XamlIlTypes.Void, true, XamlIlTypes.Object,
                 cfg.TypeSystem.GetType("Avalonia.Controls.IDeferredContent"));
+            ResourceDictionaryNotSharedDeferredAdd = ResourceDictionary.GetMethod("AddNotSharedDeferred", XamlIlTypes.Void, true, XamlIlTypes.Object,
+                cfg.TypeSystem.GetType("Avalonia.Controls.IDeferredContent"));
+
             ResourceDictionaryEnsureCapacity = ResourceDictionary.GetMethod("EnsureCapacity", XamlIlTypes.Void, true, XamlIlTypes.Int32);
             ResourceDictionaryGetCount = ResourceDictionary.GetMethod("get_Count", XamlIlTypes.Int32, true);
             IThemeVariantProvider = cfg.TypeSystem.GetType("Avalonia.Controls.IThemeVariantProvider");

tests/Avalonia.Markup.Xaml.UnitTests/Xaml/XSharedDirectiveTests.cs

@@ -0,0 +1,54 @@
+using Avalonia.Controls;
+using Avalonia.UnitTests;
+using Xunit;
+
+namespace Avalonia.Markup.Xaml.UnitTests.Xaml;
+
+public class XSharedDirectiveTests : XamlTestBase
+{
+    [Fact]
+    public void Should_Create_New_Instance_Where_x_Share_Is_False()
+    {
+        using (UnitTestApplication.Start(TestServices.StyledWindow))
+        {
+            const string xaml = $$"""
+                                <Window xmlns="https://github.com/avaloniaui"
+                                        xmlns:sys="clr-namespace:System;assembly=netstandard"
+                                        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+                                    <Window.Resources>
+                                        <ColumnDefinitions x:Key="InplicitSharedResource">
+                                            <ColumnDefinition Width="150" />
+                                            <ColumnDefinition Width="10" />
+                                            <ColumnDefinition Width="Auto" />
+                                         </ColumnDefinitions>
+                                         <ColumnDefinitions x:Key="NotSharedResource"
+                                                            x:Shared="false">
+                                            <ColumnDefinition Width="150" />
+                                            <ColumnDefinition Width="10" />
+                                            <ColumnDefinition Width="Auto" />
+                                         </ColumnDefinitions>
+                                    </Window.Resources>
+                                </Window>
+                                """;
+            var window = (Window)AvaloniaRuntimeXamlLoader.Load(xaml);
+            window.ApplyTemplate();
+
+            var implicitSharedInstance1 = window.FindResource("ImplicitSharedResource");
+            Assert.NotNull(implicitSharedInstance1);
+            var implicitSharedInstance2 = window.FindResource("ImplicitSharedResource");
+            Assert.NotNull(implicitSharedInstance2);
+
+            Assert.Same(implicitSharedInstance1, implicitSharedInstance2);
+
+            var notSharedResource1 = window.FindResource("NotSharedResource");
+            Assert.NotNull(notSharedResource1);
+
+            var notSharedResource2 = window.FindResource("NotSharedResource");
+            Assert.NotNull(notSharedResource2);
+
+            Assert.NotSame(notSharedResource1, notSharedResource2);
+
+            Assert.Equal(notSharedResource1.ToString(), notSharedResource2.ToString());
+        }
+    }
+}