Merge pull request #7201 from jkoritzinsky/relativesource-compiledbinding

Support RelativeSource-based bindings without requiring an x:DataType property.

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

@@ -99,7 +99,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
                     }
                 }
 
-                if (startType == null)
+                Func<IXamlType> startTypeResolver = startType is not null ? () => startType : () =>
                 {
                     var parentDataContextNode = context.ParentNodes().OfType<AvaloniaXamlIlDataContextTypeMetadataNode>().FirstOrDefault();
                     if (parentDataContextNode is null)
@@ -107,10 +107,10 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
                         throw new XamlX.XamlParseException("Cannot parse a compiled binding without an explicit x:DataType directive to give a starting data type for bindings.", binding);
                     }
 
-                    startType = parentDataContextNode.DataContextType;
-                }
+                    return parentDataContextNode.DataContextType;
+                };
 
-                XamlIlBindingPathHelper.UpdateCompiledBindingExtension(context, binding, startType);
+                XamlIlBindingPathHelper.UpdateCompiledBindingExtension(context, binding, startTypeResolver, context.ParentNodes().OfType<XamlAstConstructableObjectNode>().First().Type.GetClrType());
             }
 
             return node;

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

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
 using XamlX;
@@ -11,7 +12,6 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
 {
     class AvaloniaXamlIlDataContextTypeTransformer : IXamlAstTransformer
     {
-        private const string AvaloniaNs = "https://github.com/avaloniaui";
         public IXamlAstNode Transform(AstTransformationContext context, IXamlAstNode node)
         {
             if (context.ParentNodes().FirstOrDefault() is AvaloniaXamlIlDataContextTypeMetadataNode)
@@ -120,7 +120,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
                     var parentItemsDataContext = context.ParentNodes().SkipWhile(n => n != parentObject).OfType<AvaloniaXamlIlDataContextTypeMetadataNode>().FirstOrDefault();
                     if (parentItemsDataContext != null)
                     {
-                        itemsCollectionType = XamlIlBindingPathHelper.UpdateCompiledBindingExtension(context, parentItemsBinding, parentItemsDataContext.DataContextType);
+                        itemsCollectionType = XamlIlBindingPathHelper.UpdateCompiledBindingExtension(context, parentItemsBinding, () => parentItemsDataContext.DataContextType, parentObject.Type.GetClrType());
                     }
                 }
             }
@@ -153,16 +153,18 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
             }
             else if (obj.Type.GetClrType().Equals(context.GetAvaloniaTypes().CompiledBindingExtension))
             {
-                IXamlType startType;
-                var parentDataContextNode = context.ParentNodes().OfType<AvaloniaXamlIlDataContextTypeMetadataNode>().FirstOrDefault();
-                if (parentDataContextNode is null)
+                Func<IXamlType> startTypeResolver = () =>
                 {
-                    throw new XamlX.XamlParseException("Cannot parse a compiled binding without an explicit x:DataType directive to give a starting data type for bindings.", obj);
-                }
+                    var parentDataContextNode = context.ParentNodes().OfType<AvaloniaXamlIlDataContextTypeMetadataNode>().FirstOrDefault();
+                    if (parentDataContextNode is null)
+                    {
+                        throw new XamlX.XamlParseException("Cannot parse a compiled binding without an explicit x:DataType directive to give a starting data type for bindings.", obj);
+                    }
 
-                startType = parentDataContextNode.DataContextType;
+                    return parentDataContextNode.DataContextType;
+                };
 
-                var bindingResultType = XamlIlBindingPathHelper.UpdateCompiledBindingExtension(context, obj, startType);
+                var bindingResultType = XamlIlBindingPathHelper.UpdateCompiledBindingExtension(context, obj, startTypeResolver, on.Type.GetClrType());
                 return new AvaloniaXamlIlDataContextTypeMetadataNode(on, bindingResultType);
             }
 

src/Markup/Avalonia.Markup.Xaml.Loader/CompilerExtensions/XamlIlBindingPathHelper.cs

@@ -20,7 +20,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
 {
     static class XamlIlBindingPathHelper
     {
-        public static IXamlType UpdateCompiledBindingExtension(AstTransformationContext context, XamlAstConstructableObjectNode binding, IXamlType startType)
+        public static IXamlType UpdateCompiledBindingExtension(AstTransformationContext context, XamlAstConstructableObjectNode binding, Func<IXamlType> startTypeResolver, IXamlType selfType)
         {
             IXamlType bindingResultType = null;
             if (binding.Arguments.Count > 0 && binding.Arguments[0] is ParsedBindingPathNode bindingPath)
@@ -28,7 +28,8 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
                 var transformed = TransformBindingPath(
                     context,
                     bindingPath,
-                    startType,
+                    startTypeResolver,
+                    selfType,
                     bindingPath.Path);
 
                 bindingResultType = transformed.BindingResultType;
@@ -41,7 +42,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
 
                 if (bindingPathAssignment is null)
                 {
-                    return startType;
+                    return startTypeResolver();
                 }
 
                 if (bindingPathAssignment.Values[0] is ParsedBindingPathNode bindingPathNode)
@@ -49,7 +50,8 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
                     var transformed = TransformBindingPath(
                         context,
                         bindingPathNode,
-                        startType,
+                        startTypeResolver,
+                        selfType,
                         bindingPathNode.Path);
 
                     bindingResultType = transformed.BindingResultType;
@@ -64,13 +66,13 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
             return bindingResultType;
         }
 
-        private static IXamlIlBindingPathNode TransformBindingPath(AstTransformationContext context, IXamlLineInfo lineInfo, IXamlType startType, IEnumerable<BindingExpressionGrammar.INode> bindingExpression)
+        private static IXamlIlBindingPathNode TransformBindingPath(AstTransformationContext context, IXamlLineInfo lineInfo, Func<IXamlType> startTypeResolver, IXamlType selfType, IEnumerable<BindingExpressionGrammar.INode> bindingExpression)
         {
             List<IXamlIlBindingPathElementNode> transformNodes = new List<IXamlIlBindingPathElementNode>();
             List<IXamlIlBindingPathElementNode> nodes = new List<IXamlIlBindingPathElementNode>();
             foreach (var astNode in bindingExpression)
             {
-                var targetType = nodes.Count == 0 ? startType : nodes[nodes.Count - 1].Type;
+                var targetTypeResolver = nodes.Count == 0 ? startTypeResolver : () => nodes[nodes.Count - 1].Type;
                 switch (astNode)
                 {
                     case BindingExpressionGrammar.EmptyExpressionNode _:
@@ -79,59 +81,66 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
                         transformNodes.Add(new XamlIlNotPathElementNode(context.Configuration.WellKnownTypes.Boolean));
                         break;
                     case BindingExpressionGrammar.StreamNode _:
-                        IXamlType observableType;
-                        if (targetType.GenericTypeDefinition?.Equals(context.Configuration.TypeSystem.FindType("System.IObservable`1")) == true)
                         {
-                            observableType = targetType;
-                        }
-                        else
-                        {
-                            observableType = targetType.GetAllInterfaces().FirstOrDefault(i => i.GenericTypeDefinition?.Equals(context.Configuration.TypeSystem.FindType("System.IObservable`1")) ?? false);
-                        }
+                            IXamlType targetType = targetTypeResolver();
+                            IXamlType observableType;
+                            if (targetType.GenericTypeDefinition?.Equals(context.Configuration.TypeSystem.FindType("System.IObservable`1")) == true)
+                            {
+                                observableType = targetType;
+                            }
+                            else
+                            {
+                                observableType = targetType.GetAllInterfaces().FirstOrDefault(i => i.GenericTypeDefinition?.Equals(context.Configuration.TypeSystem.FindType("System.IObservable`1")) ?? false);
+                            }
 
-                        if (observableType != null)
-                        {
-                            nodes.Add(new XamlIlStreamObservablePathElementNode(observableType.GenericArguments[0]));
-                            break;
-                        }
-                        bool foundTask = false;
-                        for (var currentType = targetType; currentType != null; currentType = currentType.BaseType)
-                        {
-                            if (currentType.GenericTypeDefinition.Equals(context.Configuration.TypeSystem.GetType("System.Threading.Tasks.Task`1")))
+                            if (observableType != null)
                             {
-                                foundTask = true;
-                                nodes.Add(new XamlIlStreamTaskPathElementNode(currentType.GenericArguments[0]));
+                                nodes.Add(new XamlIlStreamObservablePathElementNode(observableType.GenericArguments[0]));
                                 break;
                             }
+                            bool foundTask = false;
+                            for (var currentType = targetType; currentType != null; currentType = currentType.BaseType)
+                            {
+                                if (currentType.GenericTypeDefinition.Equals(context.Configuration.TypeSystem.GetType("System.Threading.Tasks.Task`1")))
+                                {
+                                    foundTask = true;
+                                    nodes.Add(new XamlIlStreamTaskPathElementNode(currentType.GenericArguments[0]));
+                                    break;
+                                }
+                            }
+                            if (foundTask)
+                            {
+                                break;
+                            }
+                            throw new XamlX.XamlParseException($"Compiled bindings do not support stream bindings for objects of type {targetType.FullName}.", lineInfo);
                         }
-                        if (foundTask)
-                        {
-                            break;
-                        }
-                        throw new XamlX.XamlParseException($"Compiled bindings do not support stream bindings for objects of type {targetType.FullName}.", lineInfo);
                     case BindingExpressionGrammar.PropertyNameNode propName:
-                        var avaloniaPropertyFieldNameMaybe = propName.PropertyName + "Property";
-                        var avaloniaPropertyFieldMaybe = targetType.GetAllFields().FirstOrDefault(f =>
-                            f.IsStatic && f.IsPublic && f.Name == avaloniaPropertyFieldNameMaybe);
-
-                        if (avaloniaPropertyFieldMaybe != null)
                         {
-                            nodes.Add(new XamlIlAvaloniaPropertyPropertyPathElementNode(avaloniaPropertyFieldMaybe,
-                                XamlIlAvaloniaPropertyHelper.GetAvaloniaPropertyType(avaloniaPropertyFieldMaybe, context.GetAvaloniaTypes(), lineInfo)));
-                        }
-                        else
-                        {
-                            var clrProperty = GetAllDefinedProperties(targetType).FirstOrDefault(p => p.Name == propName.PropertyName);
+                            IXamlType targetType = targetTypeResolver();
+                            var avaloniaPropertyFieldNameMaybe = propName.PropertyName + "Property";
+                            var avaloniaPropertyFieldMaybe = targetType.GetAllFields().FirstOrDefault(f =>
+                                f.IsStatic && f.IsPublic && f.Name == avaloniaPropertyFieldNameMaybe);
 
-                            if (clrProperty is null)
+                            if (avaloniaPropertyFieldMaybe != null)
+                            {
+                                nodes.Add(new XamlIlAvaloniaPropertyPropertyPathElementNode(avaloniaPropertyFieldMaybe,
+                                    XamlIlAvaloniaPropertyHelper.GetAvaloniaPropertyType(avaloniaPropertyFieldMaybe, context.GetAvaloniaTypes(), lineInfo)));
+                            }
+                            else
                             {
-                                throw new XamlX.XamlParseException($"Unable to resolve property of name '{propName.PropertyName}' on type '{targetType}'.", lineInfo);
+                                var clrProperty = GetAllDefinedProperties(targetType).FirstOrDefault(p => p.Name == propName.PropertyName);
+
+                                if (clrProperty is null)
+                                {
+                                    throw new XamlX.XamlParseException($"Unable to resolve property of name '{propName.PropertyName}' on type '{targetType}'.", lineInfo);
+                                }
+                                nodes.Add(new XamlIlClrPropertyPathElementNode(clrProperty));
                             }
-                            nodes.Add(new XamlIlClrPropertyPathElementNode(clrProperty));
+                            break;
                         }
-                        break;
                     case BindingExpressionGrammar.IndexerNode indexer:
                         {
+                            IXamlType targetType = targetTypeResolver();
                             if (targetType.IsArray)
                             {
                                 nodes.Add(new XamlIlArrayIndexerPathElementNode(targetType, indexer.Arguments, lineInfo));
@@ -183,7 +192,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions
                             XamlIlAvaloniaPropertyHelper.GetAvaloniaPropertyType(avaloniaPropertyField, context.GetAvaloniaTypes(), lineInfo)));
                         break;
                     case BindingExpressionGrammar.SelfNode _:
-                        nodes.Add(new SelfPathElementNode(targetType));
+                        nodes.Add(new SelfPathElementNode(selfType));
                         break;
                     case VisualAncestorBindingExpressionNode visualAncestor:
                         nodes.Add(new FindVisualAncestorPathElementNode(visualAncestor.Type, visualAncestor.Level));

tests/Avalonia.Markup.Xaml.UnitTests/MarkupExtensions/CompiledBindingExtensionTests.cs

@@ -731,8 +731,7 @@ namespace Avalonia.Markup.Xaml.UnitTests.MarkupExtensions
 <Window xmlns='https://github.com/avaloniaui'
         xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'
         xmlns:local='clr-namespace:Avalonia.Markup.Xaml.UnitTests.MarkupExtensions;assembly=Avalonia.Markup.Xaml.UnitTests'
-        Title='foo'
-        x:DataType='local:TestDataContext'>
+        Title='foo'>
     <ContentControl Content='{CompiledBinding $parent.Title}' Name='contentControl' />
 </Window>";
                 var window = (Window)AvaloniaRuntimeXamlLoader.Load(xaml);
@@ -1042,6 +1041,27 @@ namespace Avalonia.Markup.Xaml.UnitTests.MarkupExtensions
             }
         }
 
+        [Fact]
+        public void Binds_To_Self_Without_DataType()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            {
+                var xaml = @"
+<Window xmlns='https://github.com/avaloniaui'
+        xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'
+        xmlns:local='clr-namespace:Avalonia.Markup.Xaml.UnitTests.MarkupExtensions;assembly=Avalonia.Markup.Xaml.UnitTests'>
+    <TextBlock Name='textBlock' Text='{CompiledBinding $self.Name}' />
+</Window>";
+                var window = (Window)AvaloniaRuntimeXamlLoader.Load(xaml);
+                var textBlock = window.FindControl<TextBlock>("textBlock");
+
+                window.ApplyTemplate();
+                window.Presenter.ApplyTemplate();
+
+                Assert.Equal(textBlock.Name, textBlock.Text);
+            }
+        }
+
         void Throws(string type, Action cb)
         {
             try