[Rgen] Start implementing the missing parts of the data model for the transformer.

src/rgen/Microsoft.Macios.Generator/DataModel/TypeInfo.Generator.cs

@@ -47,7 +47,6 @@ symbol is IArrayTypeSymbol arrayTypeSymbol
 			IsArray = true;
 			ArrayElementTypeIsWrapped = arraySymbol.ElementType.IsWrapped ();
 		}
-		IsArray = symbol is IArrayTypeSymbol;
 
 		// try to get the named type symbol to have more educated decisions
 		var namedTypeSymbol = symbol as INamedTypeSymbol;

src/rgen/Microsoft.Macios.Transformer/DataModel/Parameter.Transformer.cs

@@ -2,6 +2,10 @@
 // Licensed under the MIT License.
 
 using Microsoft.Macios.Transformer.Attributes;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.Macios.Generator.Extensions;
 
 namespace Microsoft.Macios.Generator.DataModel;
 
@@ -11,4 +15,29 @@ readonly partial struct Parameter {
 	/// Returns the bind from data if present in the binding.
 	/// </summary>
 	public BindAsData? BindAs => BindAsAttribute;
+
+	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);
+		}
+
+		// retrieve the parameter attributes because those might affect the parameter type, for example, the 
+		// NullAllowed attribute can change the parameter type to be nullable.
+		var parameterAttrs = symbol.GetAttributeData ();
+		parameter = new (symbol.Ordinal, new (symbol.Type, parameterAttrs), 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),
+			AttributesDictionary = parameterAttrs,
+		};
+		return true;
+	}
 }

src/rgen/Microsoft.Macios.Transformer/DataModel/TypeInfo.Transformer.cs

@@ -2,18 +2,46 @@
 // Licensed under the MIT License.
 
 using Microsoft.CodeAnalysis;
+using Microsoft.Macios.Generator.Extensions;
+using Microsoft.Macios.Transformer;
+using Microsoft.Macios.Transformer.Extensions;
 
 namespace Microsoft.Macios.Generator.DataModel;
 
 readonly partial struct TypeInfo {
 
-	internal TypeInfo (ITypeSymbol symbol) :
+	internal TypeInfo (ITypeSymbol symbol, Dictionary<string, List<AttributeData>> attributes) :
 		this (
 			symbol is IArrayTypeSymbol arrayTypeSymbol
 				? arrayTypeSymbol.ElementType.ToDisplayString ()
 				: symbol.ToDisplayString ().Trim ('?', '[', ']'),
 			symbol.SpecialType)
 	{
-		throw new NotImplementedException ();
+		IsNullable = attributes.HasNullAllowedFlag ();
+		// special case, the old bindings might not have the ? operator but will have the attr 
+		IsBlittable = symbol.IsBlittable () && !IsNullable;
+		IsSmartEnum = symbol.IsSmartEnum ();
+		IsReferenceType = symbol.IsReferenceType;
+		IsStruct = symbol.TypeKind == TypeKind.Struct;
+		IsInterface = symbol.TypeKind == TypeKind.Interface;
+		IsNativeIntegerType = symbol.IsNativeIntegerType;
+		IsNativeEnum = symbol.HasAttribute (AttributesNames.NativeAttribute);
+
+		// data that we can get from the symbol without being INamedType
+		symbol.GetInheritance (
+			isNSObject: out isNSObject,
+			isNativeObject: out isINativeObject,
+			isDictionaryContainer: out isDictionaryContainer,
+			parents: out parents,
+			interfaces: out interfaces);
+		IsArray = symbol is IArrayTypeSymbol;
+
+		// try to get the named type symbol to have more educated decisions
+		var namedTypeSymbol = symbol as INamedTypeSymbol;
+
+		// store the enum special type, useful when generate code that needs to cast
+		EnumUnderlyingType = namedTypeSymbol?.EnumUnderlyingType?.SpecialType;
+		MetadataName = SpecialType is SpecialType.None or SpecialType.System_Void
+			? null : symbol.MetadataName;
 	}
 }

tests/rgen/Microsoft.Macios.Generator.Tests/TestDataFactory.cs

@@ -35,7 +35,7 @@ public static TypeInfo ReturnTypeForString (bool isNullable = false)
 			IsINativeObject = false,
 		};
 
-	public static TypeInfo ReturnTypeForInt (bool isNullable = false)
+	public static TypeInfo ReturnTypeForInt (bool isNullable = false, bool keepInterfaces = false)
 		=> new (
 			name: "int",
 			specialType: SpecialType.System_Int32,
@@ -44,7 +44,7 @@ public static TypeInfo ReturnTypeForInt (bool isNullable = false)
 			isStruct: true
 		) {
 			Parents = ["System.ValueType", "object"],
-			Interfaces = isNullable
+			Interfaces = isNullable && !keepInterfaces
 				? []
 				: [
 					"System.IComparable",
@@ -175,17 +175,19 @@ public static TypeInfo ReturnTypeForInterface (string interfaceName)
 			IsInterface = true,
 		};
 
-	public static TypeInfo ReturnTypeForStruct (string structName)
+	public static TypeInfo ReturnTypeForStruct (string structName, bool isBlittable = false)
 		=> new (
 			name: structName,
+			isBlittable: isBlittable,
 			isStruct: true
 		) { Parents = ["System.ValueType", "object"] };
 
 	public static TypeInfo ReturnTypeForEnum (string enumName, bool isSmartEnum = false, bool isNativeEnum = false,
-		SpecialType underlyingType = SpecialType.System_Int32)
+		bool isNullable = false, bool isBlittable = true, SpecialType underlyingType = SpecialType.System_Int32)
 		=> new (
 			name: enumName,
-			isBlittable: true,
+			isNullable: isNullable,
+			isBlittable: isBlittable,
 			isSmartEnum: isSmartEnum
 		) {
 			Parents = [
@@ -300,7 +302,7 @@ public static TypeInfo ReturnTypeForDelegate (string delegateName)
 			]
 		};
 
-	public static TypeInfo ReturnTypeForNSObject (string? nsObjectName = null, bool isNullable = false)
+	public static TypeInfo ReturnTypeForNSObject (string? nsObjectName = null, bool isNullable = false, bool isApiDefinition = false)
 		=> new (
 			name: nsObjectName ?? "Foundation.NSObject",
 			isNullable: isNullable,
@@ -310,13 +312,18 @@ public static TypeInfo ReturnTypeForNSObject (string? nsObjectName = null, bool
 			IsNSObject = true,
 			IsINativeObject = true,
 			Parents = nsObjectName is null ? ["object"] : ["Foundation.NSObject", "object"],
-			Interfaces = [
-				"ObjCRuntime.INativeObject",
-				$"System.IEquatable<{nsObjectName ?? "Foundation.NSObject"}>",
-				"System.IDisposable",
-				"Foundation.INSObjectFactory",
-				"Foundation.INSObjectProtocol"
-			]
+			Interfaces = isApiDefinition
+				? [
+					"ObjCRuntime.INativeObject",
+					"Foundation.INSObjectFactory",
+				]
+				: [
+					"ObjCRuntime.INativeObject",
+					$"System.IEquatable<{nsObjectName ?? "Foundation.NSObject"}>",
+					"System.IDisposable",
+					"Foundation.INSObjectFactory",
+					"Foundation.INSObjectProtocol"
+				]
 		};
 
 	public static TypeInfo ReturnTypeForINativeObject (string nativeObjectName, bool isNullable = false)