diff --git a/src/Avalonia.Base/Data/Core/TypeCastNode.cs b/src/Avalonia.Base/Data/Core/TypeCastNode.cs new file mode 100644 index 0000000000..476fd5527f --- /dev/null +++ b/src/Avalonia.Base/Data/Core/TypeCastNode.cs @@ -0,0 +1,34 @@ +using System; +using System.Collections.Generic; +using System.Text; + +namespace Avalonia.Data.Core +{ + public class TypeCastNode : ExpressionNode + { + public override string Description => $"as {TargetType.FullName}"; + + public Type TargetType { get; } + + public TypeCastNode(Type type) + { + TargetType = type; + } + + protected virtual object Cast(object value) + { + return TargetType.IsInstanceOfType(value) ? value : null; + } + + protected override void StartListeningCore(WeakReference reference) + { + if (reference.TryGetTarget(out object target)) + { + target = Cast(target); + reference = target == null ? NullReference : new WeakReference(target); + } + + base.StartListeningCore(reference); + } + } +} diff --git a/src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj b/src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj index 3e15d2f700..217da2d50d 100644 --- a/src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj +++ b/src/Markup/Avalonia.Markup.Xaml/Avalonia.Markup.Xaml.csproj @@ -23,6 +23,7 @@ + diff --git a/src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/CompiledBindings/CompiledBindingPath.cs b/src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/CompiledBindings/CompiledBindingPath.cs index d627fe3cd3..f6636664c1 100644 --- a/src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/CompiledBindings/CompiledBindingPath.cs +++ b/src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/CompiledBindings/CompiledBindingPath.cs @@ -1,5 +1,6 @@ using System; using System.Collections.Generic; +using System.Linq; using Avalonia.Controls; using Avalonia.Data.Core; using Avalonia.Data.Core.Plugins; @@ -53,6 +54,9 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings case IStronglyTypedStreamElement stream: node = new StreamNode(stream.CreatePlugin()); break; + case ITypeCastElement typeCast: + node = new StrongTypeCastNode(typeCast.Type, typeCast.Cast); + break; default: throw new InvalidOperationException($"Unknown binding path element type {element.GetType().FullName}"); } @@ -66,6 +70,9 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings internal SourceMode SourceMode => _elements.Count > 0 && _elements[0] is IControlSourceBindingPathElement ? SourceMode.Control : SourceMode.Data; internal object RawSource { get; } + + public override string ToString() + => string.Concat(_elements.Select(e => e.ToString())); } public class CompiledBindingPathBuilder @@ -126,6 +133,12 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings return this; } + public CompiledBindingPathBuilder TypeCast() + { + _elements.Add(new TypeCastPathElement()); + return this; + } + public CompiledBindingPathBuilder SetRawSource(object rawSource) { _rawSource = rawSource; @@ -157,6 +170,9 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings public IPropertyInfo Property { get; } public Func, IPropertyInfo, IPropertyAccessor> AccessorFactory { get; } + + public override string ToString() + => $".{Property.Name}"; } internal interface IStronglyTypedStreamElement : ICompiledBindingPathElement @@ -164,6 +180,13 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings IStreamPlugin CreatePlugin(); } + internal interface ITypeCastElement : ICompiledBindingPathElement + { + Type Type { get; } + + Func Cast { get; } + } + internal class TaskStreamPathElement : IStronglyTypedStreamElement { public static readonly TaskStreamPathElement Instance = new TaskStreamPathElement(); @@ -181,6 +204,9 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings internal class SelfPathElement : ICompiledBindingPathElement, IControlSourceBindingPathElement { public static readonly SelfPathElement Instance = new SelfPathElement(); + + public override string ToString() + => "$self"; } internal class AncestorPathElement : ICompiledBindingPathElement, IControlSourceBindingPathElement @@ -193,6 +219,9 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings public Type AncestorType { get; } public int Level { get; } + + public override string ToString() + => $"$parent[{AncestorType?.Name},{Level}]"; } internal class VisualAncestorPathElement : ICompiledBindingPathElement, IControlSourceBindingPathElement @@ -217,6 +246,9 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings public INameScope NameScope { get; } public string Name { get; } + + public override string ToString() + => $"#{Name}"; } internal class ArrayElementPathElement : ICompiledBindingPathElement @@ -229,5 +261,24 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings public int[] Indices { get; } public Type ElementType { get; } + public override string ToString() + => $"[{string.Join(",", Indices)}]"; + } + + internal class TypeCastPathElement : ITypeCastElement + { + private static object TryCast(object obj) + { + if (obj is T result) + return result; + return null; + } + + public Type Type => typeof(T); + + public Func Cast => TryCast; + + public override string ToString() + => $"({Type.FullName})"; } } diff --git a/src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/CompiledBindings/StrongTypeCastNode.cs b/src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/CompiledBindings/StrongTypeCastNode.cs new file mode 100644 index 0000000000..1252ec7eca --- /dev/null +++ b/src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/CompiledBindings/StrongTypeCastNode.cs @@ -0,0 +1,18 @@ +using System; +using Avalonia.Data.Core; + +namespace Avalonia.Markup.Xaml.MarkupExtensions.CompiledBindings +{ + public class StrongTypeCastNode : TypeCastNode + { + private Func _cast; + + public StrongTypeCastNode(Type type, Func cast) : base(type) + { + _cast = cast; + } + + protected override object Cast(object value) + => _cast(value); + } +}