[RGen] Implement the BindFrom attribute. (#22087)

The BindFromAttribute is similar to the BindAsAttribute but in the opossite direction. This allows the bindings to be cleaner since we can specify in the partial method the return type we really want and the NSNumber/NSString transformation will be done in the generated code. --------- Co-authored-by: GitHub Actions Autoformatter <[email protected]> Co-authored-by: Jonathan Peppers <[email protected]>
xamarin · Feb 1, 2025 · 5c5febc · 5c5febc
1 parent f3c4396
commit 5c5febc
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Showing 21 changed files with 345 additions and 38 deletions.
diff --git a/src/ObjCBindings/BindFromAttribute.cs b/src/ObjCBindings/BindFromAttribute.cs
@@ -0,0 +1,35 @@
+using System;
+using System.Reflection;
+using System.Diagnostics.CodeAnalysis;
+using ObjCRuntime;
+
+#nullable enable
+
+namespace ObjCBindings {
+
+	/// <summary>
+	/// Attribute to bind from a specific type.
+	/// </summary>
+	[Experimental ("APL0003")]
+	[AttributeUsage (AttributeTargets.ReturnValue | AttributeTargets.Property | AttributeTargets.Parameter, AllowMultiple = false)]
+	public class BindFromAttribute : Attribute {
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="BindFromAttribute"/> class.
+		/// </summary>
+		public BindFromAttribute (Type type)
+		{
+			Type = type;
+		}
+
+		/// <summary>
+		/// The type to bind from.
+		/// </summary>
+		public Type Type { get; set; }
+
+		/// <summary>
+		/// The original type that was bound from.
+		/// </summary>
+		public Type? OriginalType { get; set; } = null;
+	}
+}
diff --git a/src/frameworks.sources b/src/frameworks.sources
@@ -1935,6 +1935,7 @@ SHARED_CORE_SOURCES = \
 	DotNetGlobals.cs \
 	MinimumVersions.cs \
 	MonoPInvokeCallbackAttribute.cs \
+	ObjCBindings/BindFromAttribute.cs \
 	ObjCBindings/BindingTypeAttribute.cs \
 	ObjCBindings/BindingTypeTag.cs \
 	ObjCBindings/ExportAttribute.cs \

diff --git a/src/rgen/Microsoft.Macios.Bindings.Analyzer/Microsoft.Macios.Bindings.Analyzer.csproj b/src/rgen/Microsoft.Macios.Bindings.Analyzer/Microsoft.Macios.Bindings.Analyzer.csproj
@@ -39,6 +39,9 @@
         <Compile Include="../Microsoft.Macios.Generator/DictionaryComparer.cs" >
             <Link>Generator/DictionaryComparer.cs</Link>
         </Compile>
+        <Compile Include="../Microsoft.Macios.Generator/Attributes/BindFromData.cs" >
+            <Link>Generator/Attributes/BindFromData.cs</Link>
+        </Compile>
         <Compile Include="../Microsoft.Macios.Generator/Attributes/FieldData.cs" >
             <Link>Generator/Attributes/FieldData.cs</Link>
         </Compile>

diff --git a/src/rgen/Microsoft.Macios.Generator/Attributes/BindFromData.cs b/src/rgen/Microsoft.Macios.Generator/Attributes/BindFromData.cs
@@ -0,0 +1,98 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.CodeAnalysis;
+
+namespace Microsoft.Macios.Generator.Attributes;
+
+readonly struct BindFromData : IEquatable<BindFromData> {
+
+	public string Type { get; }
+	public string? OriginalType { get; }
+
+	public BindFromData (string type)
+	{
+		Type = type;
+	}
+
+	public BindFromData (string type, string? originalType)
+	{
+		Type = type;
+		OriginalType = originalType;
+	}
+
+
+	public static bool TryParse (AttributeData attributeData,
+		[NotNullWhen (true)] out BindFromData? data)
+	{
+		data = null;
+		var count = attributeData.ConstructorArguments.Length;
+		string? type;
+		string? originalType = null;
+
+		switch (count) {
+		case 1:
+			type = ((INamedTypeSymbol) attributeData.ConstructorArguments [0].Value!).ToDisplayString ();
+			break;
+		default:
+			// no other constructors are available
+			return false;
+		}
+
+		if (attributeData.NamedArguments.Length == 0) {
+			data = new (type);
+			return true;
+		}
+
+		foreach (var (name, value) in attributeData.NamedArguments) {
+			switch (name) {
+			case "Type":
+				type = ((INamedTypeSymbol) value.Value!).ToDisplayString ();
+				break;
+			case "OriginalType":
+				originalType = ((INamedTypeSymbol) value.Value!).ToDisplayString ();
+				break;
+			default:
+				data = null;
+				return false;
+			}
+		}
+		data = new (type, originalType);
+		return true;
+	}
+
+	/// <inheritdoc />
+	public bool Equals (BindFromData other)
+	{
+		return Type == other.Type && OriginalType == other.OriginalType;
+	}
+
+	/// <inheritdoc />
+	public override bool Equals (object? obj)
+	{
+		return obj is BindFromData other && Equals (other);
+	}
+
+	/// <inheritdoc />
+	public override int GetHashCode ()
+	{
+		return HashCode.Combine (Type, OriginalType);
+	}
+
+	public static bool operator == (BindFromData x, BindFromData y)
+	{
+		return x.Equals (y);
+	}
+
+	public static bool operator != (BindFromData x, BindFromData y)
+	{
+		return !(x == y);
+	}
+
+	public override string ToString ()
+	{
+		return $"{{ Type: '{Type}', OriginalType: '{OriginalType ?? "null"}' }}";
+	}
+}
diff --git a/src/rgen/Microsoft.Macios.Generator/Attributes/FieldData.cs b/src/rgen/Microsoft.Macios.Generator/Attributes/FieldData.cs
@@ -137,6 +137,6 @@ public override int GetHashCode ()
 	/// <inheritdoc />
 	public override string ToString ()
 	{
-		return $"{{ SymbolName: '{SymbolName}' LibraryName: '{LibraryName ?? "null"}', Flags: '{Flags}' }}";
+		return $"{{ SymbolName: '{SymbolName}', LibraryName: '{LibraryName ?? "null"}', Flags: '{Flags}' }}";
 	}
 }
diff --git a/src/rgen/Microsoft.Macios.Generator/AttributesNames.cs b/src/rgen/Microsoft.Macios.Generator/AttributesNames.cs
@@ -12,6 +12,7 @@ static class AttributesNames {
 	public const string BindingAttribute = "ObjCBindings.BindingTypeAttribute";
 	public const string BindingCategoryAttribute = "ObjCBindings.BindingTypeAttribute<ObjCBindings.Category>";
 	public const string BindingClassAttribute = "ObjCBindings.BindingTypeAttribute<ObjCBindings.Class>";
+	public const string BindFromAttribute = "ObjCBindings.BindFromAttribute";
 	public const string BindingProtocolAttribute = "ObjCBindings.BindingTypeAttribute<ObjCBindings.Protocol>";
 	public const string BindingStrongDictionaryAttribute = "ObjCBindings.BindingTypeAttribute<ObjCBindings.StrongDictionary>";
 	public const string FieldAttribute = "ObjCBindings.FieldAttribute";

diff --git a/src/rgen/Microsoft.Macios.Generator/DataModel/Method.Generator.cs b/src/rgen/Microsoft.Macios.Generator/DataModel/Method.Generator.cs
@@ -20,6 +20,11 @@ readonly partial struct Method {
 	/// </summary>
 	public ExportData<ObjCBindings.Method> ExportMethodData { get; }
 
+	/// <summary>
+	/// Returns the bind from data if present in the binding.
+	/// </summary>
+	public BindFromData? BindAs { get; init; }
+
 	/// <summary>
 	/// Returns if the method was marked as thread safe.
 	/// </summary>
@@ -79,7 +84,9 @@ public static bool TryCreate (MethodDeclarationSyntax declaration, RootBindingCo
 			exportMethodData: exportData,
 			attributes: attributes,
 			modifiers: [.. declaration.Modifiers],
-			parameters: parametersBucket.ToImmutableArray ());
+			parameters: parametersBucket.ToImmutableArray ()) {
+			BindAs = method.GetBindFromData (),
+		};
 
 		return true;
 	}

diff --git a/src/rgen/Microsoft.Macios.Generator/DataModel/Method.cs b/src/rgen/Microsoft.Macios.Generator/DataModel/Method.cs
@@ -61,6 +61,8 @@ public bool Equals (Method other)
 			return false;
 		if (ExportMethodData != other.ExportMethodData)
 			return false;
+		if (BindAs != other.BindAs)
+			return false;
 
 		var attrsComparer = new AttributesEqualityComparer ();
 		if (!attrsComparer.Equals (Attributes, other.Attributes))
@@ -86,6 +88,7 @@ public override int GetHashCode ()
 		hashCode.Add (Type);
 		hashCode.Add (Name);
 		hashCode.Add (ReturnType);
+		hashCode.Add (BindAs);
 		foreach (var modifier in Modifiers) {
 			hashCode.Add (modifier);
 		}
@@ -119,6 +122,7 @@ public override string ToString ()
 		sb.Append ($"ReturnType: {ReturnType}, ");
 		sb.Append ($"SymbolAvailability: {SymbolAvailability}, ");
 		sb.Append ($"ExportMethodData: {ExportMethodData}, ");
+		sb.Append ($"BindAs: {BindAs}, ");
 		sb.Append ("Attributes: [");
 		sb.AppendJoin (", ", Attributes);
 		sb.Append ("], Modifiers: [");

diff --git a/src/rgen/Microsoft.Macios.Generator/DataModel/Parameter.Generator.cs b/src/rgen/Microsoft.Macios.Generator/DataModel/Parameter.Generator.cs
@@ -1,6 +1,12 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.Macios.Generator.Attributes;
+using Microsoft.Macios.Generator.Extensions;
+
 namespace Microsoft.Macios.Generator.DataModel;
 
 readonly partial struct Parameter {
@@ -15,6 +21,33 @@ public enum VariableType {
 		StringPointer,
 	}
 
+	/// <summary>
+	/// Returns the bind from data if present in the binding.
+	/// </summary>
+	public BindFromData? BindAs { get; init; }
+
+	public static bool TryCreate (IParameterSymbol symbol, ParameterSyntax declaration, SemanticModel semanticModel,
+		[NotNullWhen (true)] out Parameter? parameter)
+	{
+		DelegateInfo? delegateInfo = null;
+		if (symbol.Type is INamedTypeSymbol namedTypeSymbol
+			&& namedTypeSymbol.DelegateInvokeMethod is not null) {
+			DelegateInfo.TryCreate (namedTypeSymbol.DelegateInvokeMethod, out delegateInfo);
+		}
+
+		parameter = new (symbol.Ordinal, new (symbol.Type), symbol.Name) {
+			BindAs = symbol.GetBindFromData (),
+			IsOptional = symbol.IsOptional,
+			IsParams = symbol.IsParams,
+			IsThis = symbol.IsThis,
+			DefaultValue = (symbol.HasExplicitDefaultValue) ? symbol.ExplicitDefaultValue?.ToString () : null,
+			ReferenceKind = symbol.RefKind.ToReferenceKind (),
+			Delegate = delegateInfo,
+			Attributes = declaration.GetAttributeCodeChanges (semanticModel),
+		};
+		return true;
+	}
+
 	/// <summary>
 	/// Returns the name of the aux variable that would have needed for the given parameter. Use the
 	/// variable type to name it.

diff --git a/src/rgen/Microsoft.Macios.Generator/DataModel/Parameter.cs b/src/rgen/Microsoft.Macios.Generator/DataModel/Parameter.cs
@@ -79,27 +79,6 @@ public Parameter (int position, TypeInfo type, string name)
 		Name = name;
 	}
 
-	public static bool TryCreate (IParameterSymbol symbol, ParameterSyntax declaration, SemanticModel semanticModel,
-		[NotNullWhen (true)] out Parameter? parameter)
-	{
-		DelegateInfo? delegateInfo = null;
-		if (symbol.Type is INamedTypeSymbol namedTypeSymbol
-			&& namedTypeSymbol.DelegateInvokeMethod is not null) {
-			DelegateInfo.TryCreate (namedTypeSymbol.DelegateInvokeMethod, out delegateInfo);
-		}
-
-		parameter = new (symbol.Ordinal, new (symbol.Type), symbol.Name) {
-			IsOptional = symbol.IsOptional,
-			IsParams = symbol.IsParams,
-			IsThis = symbol.IsThis,
-			DefaultValue = (symbol.HasExplicitDefaultValue) ? symbol.ExplicitDefaultValue?.ToString () : null,
-			ReferenceKind = symbol.RefKind.ToReferenceKind (),
-			Delegate = delegateInfo,
-			Attributes = declaration.GetAttributeCodeChanges (semanticModel),
-		};
-		return true;
-	}
-
 	/// <inheritdoc/>
 	public bool Equals (Parameter other)
 	{
@@ -119,6 +98,8 @@ public bool Equals (Parameter other)
 			return false;
 		if (ReferenceKind != other.ReferenceKind)
 			return false;
+		if (BindAs != other.BindAs)
+			return false;
 		if (Delegate != other.Delegate)
 			return false;
 
@@ -145,6 +126,7 @@ public override int GetHashCode ()
 		hashCode.Add (DefaultValue);
 		hashCode.Add ((int) ReferenceKind);
 		hashCode.Add (Delegate);
+		hashCode.Add (BindAs);
 		return hashCode.ToHashCode ();
 	}
 
@@ -165,13 +147,14 @@ public override string ToString ()
 		sb.Append ($"Position: {Position}, ");
 		sb.Append ($"Type: {Type}, ");
 		sb.Append ($"Name: {Name}, ");
-		sb.Append ("Attributes: ");
+		sb.Append ("Attributes: [");
 		sb.AppendJoin (", ", Attributes);
-		sb.Append ($" IsOptional: {IsOptional}, ");
+		sb.Append ($"] IsOptional: {IsOptional}, ");
 		sb.Append ($"IsParams: {IsParams}, ");
 		sb.Append ($"IsThis: {IsThis}, ");
 		sb.Append ($"DefaultValue: {DefaultValue}, ");
 		sb.Append ($"ReferenceKind: {ReferenceKind}, ");
+		sb.Append ($"BindAs: {BindAs?.ToString () ?? "null"}, ");
 		sb.Append ($"Delegate: {Delegate?.ToString () ?? "null"} }}");
 		return sb.ToString ();
 	}

diff --git a/src/rgen/Microsoft.Macios.Generator/DataModel/Property.Generator.cs b/src/rgen/Microsoft.Macios.Generator/DataModel/Property.Generator.cs
@@ -53,6 +53,11 @@ public bool IsNotification
 	public bool MarshalNativeExceptions
 		=> IsProperty && ExportPropertyData.Value.Flags.HasFlag (ObjCBindings.Property.MarshalNativeExceptions);
 
+	/// <summary>
+	/// Returns the bind from data if present in the binding.
+	/// </summary>
+	public BindFromData? BindAs { get; init; }
+
 	/// <summary>
 	/// True if the property should be generated without a backing field.
 	/// </summary>
@@ -164,6 +169,7 @@ public static bool TryCreate (PropertyDeclarationSyntax declaration, RootBinding
 			attributes: attributes,
 			modifiers: [.. declaration.Modifiers],
 			accessors: accessorCodeChanges) {
+			BindAs = propertySymbol.GetBindFromData (),
 			ExportFieldData = GetFieldInfo (context, propertySymbol),
 			ExportPropertyData = propertySymbol.GetExportData<ObjCBindings.Property> (),
 		};
@@ -190,6 +196,7 @@ public override string ToString ()
 		sb.Append ($"IsTransient: '{IsTransient}', ");
 		sb.Append ($"NeedsBackingField: '{NeedsBackingField}', ");
 		sb.Append ($"RequiresDirtyCheck: '{RequiresDirtyCheck}', ");
+		sb.Append ($"BindAs: '{BindAs}', ");
 		sb.Append ("Attributes: [");
 		sb.AppendJoin (",", Attributes);
 		sb.Append ("], Modifiers: [");

diff --git a/src/rgen/Microsoft.Macios.Generator/DataModel/Property.cs b/src/rgen/Microsoft.Macios.Generator/DataModel/Property.cs
@@ -113,6 +113,8 @@ bool CoreEquals (Property other)
 			return false;
 		if (ExportPropertyData != other.ExportPropertyData)
 			return false;
+		if (BindAs != other.BindAs)
+			return false;
 
 		var attrsComparer = new AttributesEqualityComparer ();
 		if (!attrsComparer.Equals (Attributes, other.Attributes))

diff --git a/src/rgen/Microsoft.Macios.Generator/Extensions/TypeSymbolExtensions.Core.cs b/src/rgen/Microsoft.Macios.Generator/Extensions/TypeSymbolExtensions.Core.cs
@@ -27,11 +27,6 @@ static partial class TypeSymbolExtensions {
 	public static Dictionary<string, List<AttributeData>> GetAttributeData (this ISymbol symbol)
 	{
 		var boundAttributes = symbol.GetAttributes ();
-		if (boundAttributes.Length == 0) {
-			// return an empty dictionary if there are no attributes
-			return new ();
-		}
-
 		var attributes = new Dictionary<string, List<AttributeData>> ();
 		foreach (var attributeData in boundAttributes) {
 			var attrName = attributeData.AttributeClass?.ToDisplayString ();

diff --git a/src/rgen/Microsoft.Macios.Generator/Extensions/TypeSymbolExtensions.Generator.cs b/src/rgen/Microsoft.Macios.Generator/Extensions/TypeSymbolExtensions.Generator.cs
@@ -4,7 +4,6 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
-using System.Linq;
 using Microsoft.CodeAnalysis;
 using Microsoft.Macios.Generator.Attributes;
 using Microsoft.Macios.Generator.Availability;
@@ -134,6 +133,9 @@ public static BindingTypeData<T> GetBindingData<T> (this ISymbol symbol) where T
 	public static FieldData<T>? GetFieldData<T> (this ISymbol symbol) where T : Enum
 		=> GetAttribute<FieldData<T>> (symbol, AttributesNames.GetFieldAttributeName<T>, FieldData<T>.TryParse);
 
+	public static BindFromData? GetBindFromData (this ISymbol symbol)
+		=> GetAttribute<BindFromData> (symbol, AttributesNames.BindFromAttribute, BindFromData.TryParse);
+
 	public static bool X86NeedStret (ITypeSymbol returnType)
 	{
 		if (!returnType.IsValueType || returnType.SpecialType == SpecialType.System_Enum ||