[RGen] Add the code to parse the field attribute in the transformer.

src/rgen/Microsoft.Macios.Transformer/Attributes/FieldData.cs

@@ -1,25 +1,82 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.CodeAnalysis;
+
 namespace Microsoft.Macios.Transformer.Attributes;
 
 public struct FieldData : IEquatable<FieldData> {
 
+	public string SymbolName { get; }
+	public string? LibraryName { get; }
+
+	internal FieldData (string symbolName, string? libraryName)
+	{
+		SymbolName = symbolName;
+		LibraryName = libraryName;
+	}
+
+	internal FieldData (string symbolName) : this (symbolName, null) { }
+
+	public static bool TryParse (AttributeData attributeData,
+		[NotNullWhen (true)] out FieldData? data)
+	{
+		data = default;
+
+		var count = attributeData.ConstructorArguments.Length;
+		string? symbolName;
+		string? libraryName = null;
+		switch (count) {
+		case 1:
+			symbolName = (string?) attributeData.ConstructorArguments [0].Value!;
+			break;
+		case 2:
+			symbolName = (string?) attributeData.ConstructorArguments [0].Value!;
+			libraryName = (string?) attributeData.ConstructorArguments [1].Value!;
+			break;
+		default:
+			// 0 should not be an option.
+			return false;
+		}
+
+		if (attributeData.NamedArguments.Length == 0) {
+			data = new (symbolName, libraryName);
+			return true;
+		}
+
+		// LibraryName can be a param value
+		foreach (var (name, value) in attributeData.NamedArguments) {
+			switch (name) {
+			case "LibraryName":
+				libraryName = (string?) value.Value!;
+				break;
+			default:
+				data = null;
+				return false;
+			}
+		}
+		data = new (symbolName, libraryName);
+		return true;
+	}
+
 	public bool Equals (FieldData other)
 	{
-		throw new NotImplementedException ();
+		if (SymbolName != other.SymbolName)
+			return false;
+		return LibraryName == other.LibraryName;
 	}
 
 	/// <inheritdoc />
 	public override bool Equals (object? obj)
 	{
-		return obj is ExportData other && Equals (other);
+		return obj is FieldData other && Equals (other);
 	}
 
 	/// <inheritdoc />
 	public override int GetHashCode ()
 	{
-		throw new NotImplementedException ();
+		return HashCode.Combine (SymbolName, LibraryName);
 	}
 
 	public static bool operator == (FieldData x, FieldData y)
@@ -31,4 +88,9 @@ public override int GetHashCode ()
 	{
 		return !(x == y);
 	}
+
+	public override string ToString ()
+	{
+		return $"{{ SymbolName: '{SymbolName}' LibraryName: '{LibraryName ?? "null"}' }}";
+	}
 }

tests/rgen/Microsoft.Macios.Transformer.Tests/DataModel/ExportDataTests.cs

@@ -67,7 +67,7 @@ interface UIFeedbackGenerator : UIInteraction {
 
 	[Theory]
 	[AllSupportedPlatformsClassData<TestDataTryCreate>]
-	public void TryeCreateTests (ApplePlatform platform, (string Source, string Path) source, ExportData expectedData)
+	public void TryCreateTests (ApplePlatform platform, (string Source, string Path) source, ExportData expectedData)
 	{
 		// create a compilation used to create the transformer
 		var compilation = CreateCompilation (platform, sources: source);

tests/rgen/Microsoft.Macios.Transformer.Tests/DataModel/FieldDataTests.cs

@@ -0,0 +1,108 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.Collections;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.Macios.Generator.Extensions;
+using Microsoft.Macios.Transformer.Attributes;
+using Xamarin.Tests;
+using Xamarin.Utils;
+
+namespace Microsoft.Macios.Transformer.Tests;
+
+public class FieldDataTests : BaseTransformerTestClass {
+
+	class TestDataTryCreate : IEnumerable<object []> {
+		public IEnumerator<object []> GetEnumerator ()
+		{
+			const string symbolOnly = @"
+using System;
+using Foundation;
+using ObjCRuntime;
+using UIKit;
+
+namespace Test;
+
+[NoTV]
+[MacCatalyst (13, 1)]
+[DisableDefaultCtor]
+[Abstract]
+[BaseType (typeof (NSObject))]
+interface UIFeedbackGenerator : UIInteraction {
+
+	[Field (""prepare"")]
+	void Prepare { get; }
+}
+";
+			yield return [(Source: symbolOnly, Path: "/some/random/path.cs"), new FieldData ("prepare")];
+
+			const string symbolAndLibrary = @"
+using System;
+using Foundation;
+using ObjCRuntime;
+using UIKit;
+
+namespace Test;
+
+[NoTV]
+[MacCatalyst (13, 1)]
+[DisableDefaultCtor]
+[Abstract]
+[BaseType (typeof (NSObject))]
+interface UIFeedbackGenerator : UIInteraction {
+
+	[Field (""prepare"", ""LibraryName"")]
+	void Prepare { get; }
+}
+";
+			yield return [(Source: symbolAndLibrary, Path: "/some/random/path.cs"), new FieldData ("prepare", "LibraryName")];
+
+			const string symbolAndLibraryNamed = @"
+using System;
+using Foundation;
+using ObjCRuntime;
+using UIKit;
+
+namespace Test;
+
+[NoTV]
+[MacCatalyst (13, 1)]
+[DisableDefaultCtor]
+[Abstract]
+[BaseType (typeof (NSObject))]
+interface UIFeedbackGenerator : UIInteraction {
+
+	[Field (""prepare"", LibraryName = ""LibraryName"")]
+	void Prepare { get; }
+}
+";
+			yield return [(Source: symbolAndLibraryNamed, Path: "/some/random/path.cs"), new FieldData ("prepare", "LibraryName")];
+		}
+
+		IEnumerator IEnumerable.GetEnumerator () => GetEnumerator ();
+	}
+
+	[Theory]
+	[AllSupportedPlatformsClassData<TestDataTryCreate>]
+	public void TryCreateTests (ApplePlatform platform, (string Source, string Path) source, FieldData expectedData)
+	{
+		// create a compilation used to create the transformer
+		var compilation = CreateCompilation (platform, sources: source);
+		var syntaxTree = compilation.SyntaxTrees.FirstOrDefault ();
+		Assert.NotNull (syntaxTree);
+
+		var semanticModel = compilation.GetSemanticModel (syntaxTree);
+		Assert.NotNull (semanticModel);
+
+		var declaration = syntaxTree.GetRoot ()
+			.DescendantNodes ().OfType<PropertyDeclarationSyntax> ()
+			.FirstOrDefault ();
+		Assert.NotNull (declaration);
+
+		var symbol = semanticModel.GetDeclaredSymbol (declaration);
+		Assert.NotNull (symbol);
+		var fieldData = symbol.GetAttribute<FieldData> (AttributesNames.FieldAttribute, FieldData.TryParse);
+		Assert.Equal (expectedData, fieldData);
+	}
+}