[RGen] Create factory method for the NSNumber FromHandle methods. (#22312)

This new factory method will return the member access to the correct
NSNumber factory method. This is later used in the code generation when
dealing with NSNumber backed BindAs/BindFrom attributes.

---------

Co-authored-by: Rolf Bjarne Kvinge <rolf@xamarin.com>
Co-authored-by: GitHub Actions Autoformatter <github-actions-autoformatter@xamarin.com>

Author: 3 people

src/rgen/Microsoft.Macios.Generator/Emitters/BindingSyntaxFactory.Runtime.cs

@@ -6,6 +6,7 @@
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.Macios.Generator.Extensions;
+using TypeInfo = Microsoft.Macios.Generator.DataModel.TypeInfo;
 using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
 
 namespace Microsoft.Macios.Generator.Emitters;
@@ -53,9 +54,9 @@ public static InvocationExpressionSyntax GetHandle (string selector)
 	{
 		// (selector)
 		var args = ArgumentList (SingletonSeparatedList (
-					Argument (LiteralExpression (
-						SyntaxKind.StringLiteralExpression,
-						Literal (selector))))).NormalizeWhitespace ();
+			Argument (LiteralExpression (
+				SyntaxKind.StringLiteralExpression,
+				Literal (selector))))).NormalizeWhitespace ();
 
 		// Selector.GetHandle (selector)
 		return InvocationExpression (
@@ -120,16 +121,16 @@ public static InvocationExpressionSyntax MessagingInvocation (string objcMsgSend
 		var argumentList = ArgumentList (SeparatedList<ArgumentSyntax> (args));
 		// generates: ObjCRuntime.Messaging.objc_msgSend (this.Handle, Selector.GetHandle (selector), args)
 		var invocation = InvocationExpression (
-			MemberAccessExpression (
-				SyntaxKind.SimpleMemberAccessExpression,
 				MemberAccessExpression (
 					SyntaxKind.SimpleMemberAccessExpression,
-					AliasQualifiedName (
-						IdentifierName (
-							Token (SyntaxKind.GlobalKeyword)),
-						IdentifierName ("ObjCRuntime")),
-					IdentifierName ("Messaging")),
-				IdentifierName (objcMsgSendMethod).WithTrailingTrivia (Space)))
+					MemberAccessExpression (
+						SyntaxKind.SimpleMemberAccessExpression,
+						AliasQualifiedName (
+							IdentifierName (
+								Token (SyntaxKind.GlobalKeyword)),
+							IdentifierName ("ObjCRuntime")),
+						IdentifierName ("Messaging")),
+					IdentifierName (objcMsgSendMethod).WithTrailingTrivia (Space)))
 			.WithArgumentList (argumentList);
 		return invocation;
 	}
@@ -147,10 +148,10 @@ internal static InvocationExpressionSyntax StringArrayFromHandle (ImmutableArray
 
 		// generate: CFArray.StringArrayFromHandle (arg1, arg2, arg3)
 		return InvocationExpression (
-			MemberAccessExpression (
-				SyntaxKind.SimpleMemberAccessExpression,
-				IdentifierName ("CFArray"),
-				IdentifierName ("StringArrayFromHandle").WithTrailingTrivia (Space)))
+				MemberAccessExpression (
+					SyntaxKind.SimpleMemberAccessExpression,
+					IdentifierName ("CFArray"),
+					IdentifierName ("StringArrayFromHandle").WithTrailingTrivia (Space)))
 			.WithArgumentList (argumentList);
 	}
 
@@ -174,6 +175,44 @@ internal static InvocationExpressionSyntax StringFromHandle (ImmutableArray<Argu
 			.WithArgumentList (argumentList);
 	}
 
+	/// <summary>
+	/// Returns the method group needed to get a NSNumber from a handle.
+	/// </summary>
+	/// <param name="returnType">The type info of the return type.</param>
+	/// <returns>The member access to the correct NSNumber method.</returns>
+	internal static MemberAccessExpressionSyntax? NSNumberFromHandle (TypeInfo returnType)
+	{
+#pragma warning disable format
+		var memberName = returnType switch {
+			// name must be before SpecialType or you'll get them wrong values because
+			// the type we want by name also have a valid special type, the tests should catch
+			// mistakes here
+			{ Name: "NFloat" or "nfloat" } => "ToNFloat",
+			{ Name: "nint" } => "ToNInt",
+			{ Name: "nuint" } => "ToNUInt",
+			{ SpecialType: SpecialType.System_Boolean } => "ToBool",
+			{ SpecialType: SpecialType.System_Byte } => "ToByte",
+			{ SpecialType: SpecialType.System_Double } => "ToDouble",
+			{ SpecialType: SpecialType.System_Single } => "ToFloat",
+			{ SpecialType: SpecialType.System_Int16 } => "ToInt16",
+			{ SpecialType: SpecialType.System_Int32 } => "ToInt32",
+			{ SpecialType: SpecialType.System_Int64 } => "ToInt64",
+			{ SpecialType: SpecialType.System_SByte } => "ToSByte",
+			{ SpecialType: SpecialType.System_UInt16 } => "ToUInt16",
+			{ SpecialType: SpecialType.System_UInt32 } => "ToUInt32",
+			{ SpecialType: SpecialType.System_UInt64 } => "ToUInt64",
+			_ => null,
+		};
+#pragma warning restore format
+		if (memberName is null)
+			return null;
+		return MemberAccessExpression (
+			SyntaxKind.SimpleMemberAccessExpression,
+			IdentifierName ("NSNumber"),
+			IdentifierName (memberName));
+	}
+
+
 	/// <summary>
 	/// Generates a call to the NSArray.ArrayFromHandleFunc with the given arguments.
 	/// </summary>

tests/rgen/Microsoft.Macios.Generator.Tests/Emitters/BindingSyntaxFactoryRuntimeTests.cs

@@ -6,9 +6,11 @@
 using System.Collections.Immutable;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.Macios.Generator.DataModel;
 using Xunit;
 using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
 using static Microsoft.Macios.Generator.Emitters.BindingSyntaxFactory;
+using static Microsoft.Macios.Generator.Tests.TestDataFactory;
 
 namespace Microsoft.Macios.Generator.Tests.Emitters;
 
@@ -146,6 +148,77 @@ void StringFromHandleTests (ImmutableArray<ArgumentSyntax> arguments, string exp
 		Assert.Equal (expectedDeclaration, declaration.ToFullString ());
 	}
 
+	class TestDataNSNumberFromHandleTests : IEnumerable<object []> {
+		public IEnumerator<object []> GetEnumerator ()
+		{
+
+			yield return [
+				ReturnTypeForBool (),
+				"NSNumber.ToBool"
+			];
+
+			yield return [
+				ReturnTypeForInt (),
+				"NSNumber.ToInt32"
+			];
+
+			yield return [
+				ReturnTypeForInt (isUnsigned: true),
+				"NSNumber.ToUInt32"
+			];
+
+			yield return [
+				ReturnTypeForShort (),
+				"NSNumber.ToInt16"
+			];
+
+			yield return [
+				ReturnTypeForShort (isUnsigned: true),
+				"NSNumber.ToUInt16"
+			];
+
+			yield return [
+				ReturnTypeForLong (),
+				"NSNumber.ToInt64"
+			];
+
+			yield return [
+				ReturnTypeForLong (isUnsigned: true),
+				"NSNumber.ToUInt64"
+			];
+
+			yield return [
+				ReturnTypeForNInt (),
+				"NSNumber.ToNInt"
+			];
+
+			yield return [
+				ReturnTypeForNInt (isUnsigned: true),
+				"NSNumber.ToNUInt"
+			];
+
+			yield return [
+				ReturnTypeForDouble (),
+				"NSNumber.ToDouble"
+			];
+
+			yield return [
+				ReturnTypeForFloat (),
+				"NSNumber.ToFloat"
+			];
+		}
+
+		IEnumerator IEnumerable.GetEnumerator () => GetEnumerator ();
+	}
+
+	[Theory]
+	[ClassData (typeof (TestDataNSNumberFromHandleTests))]
+	void NSNumberFromHandleTests (TypeInfo returnType, string expectedDeclaration)
+	{
+		var declaration = NSNumberFromHandle (returnType);
+		Assert.Equal (expectedDeclaration, declaration?.ToFullString ());
+	}
+
 	class TestDataNSArrayFromHandleFunc : IEnumerable<object []> {
 		public IEnumerator<object []> GetEnumerator ()
 		{