support objects as associated values

Author: madsodgaard

Samples/JExtractJNISampleApp/src/test/java/com/example/swift/VehicleEnumTest.java

@@ -114,6 +114,16 @@ void getAsMotorbike() {
         }
     }
 
+    @Test
+    void getAsTransformer() {
+        try (var arena = new ConfinedSwiftMemorySession()) {
+            Vehicle vehicle = Vehicle.transformer(Vehicle.bicycle(arena), Vehicle.car("BMW", arena), arena);
+            Vehicle.Transformer transformer = vehicle.getAsTransformer(arena).orElseThrow();
+            assertTrue(transformer.front().getAsBicycle().isPresent());
+            assertEquals("BMW", transformer.back().getAsCar().orElseThrow().arg0());
+        }
+    }
+
     @Test
     void associatedValuesAreCopied() {
         try (var arena = new ConfinedSwiftMemorySession()) {

Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaBindingsPrinting.swift

@@ -265,16 +265,17 @@ extension JNISwift2JavaGenerator {
           var nativeResults = zip(translatedCase.translatedValues, translatedCase.conversions).map { value, conversion in
             "\(conversion.native.javaType) \(value.parameter.name)"
           }
-          if requiresSwiftArena {
-            nativeResults.append("SwiftArena swiftArena$")
-          }
+          printer.print("record $NativeParameters(\(nativeResults.joined(separator: ", "))) {}")
+          printer.println()
+
           printer.print(#"@SuppressWarnings("unused")"#)
-          printer.printBraceBlock("static \(caseName) fromJNI(\(nativeResults.joined(separator: ", ")))") { printer in
+          let swiftArenaParameter = requiresSwiftArena ? ", SwiftArena swiftArena$" : ""
+          printer.printBraceBlock("\(caseName)($NativeParameters parameters\(swiftArenaParameter))") { printer in
             let memberValues = zip(translatedCase.translatedValues, translatedCase.conversions).map { (value, conversion) in
-              let result = conversion.translated.conversion.render(&printer, value.parameter.name)
+              let result = conversion.translated.conversion.render(&printer, "parameters.\(value.parameter.name)")
               return result
             }
-            printer.print("return new \(caseName)(\(memberValues.joined(separator: ", ")));")
+            printer.print("this(\(memberValues.joined(separator: ", ")));")
           }
         }
       }
@@ -291,24 +292,22 @@ extension JNISwift2JavaGenerator {
           """
         )
         if hasParameters {
-          var arguments = ["this.$memoryAddress()"]
+          var arguments = ["$getAs\(caseName)(this.$memoryAddress())"]
           if requiresSwiftArena {
             arguments.append("swiftArena$")
           }
           printer.print(
           """
-          return Optional.of($getAs\(caseName)(\(arguments.joined(separator: ", "))));
+          return Optional.of(new \(caseName)(\(arguments.joined(separator: ", "))));
           """
           )
         } else {
           printer.print("return Optional.of(new \(caseName)());")
         }
       }
-      var nativeParameters = ["long self"]
-      if requiresSwiftArena {
-        nativeParameters.append("SwiftArena swiftArena$")
+      if hasParameters {
+        printer.print("private static native \(caseName).$NativeParameters $getAs\(caseName)(long self);")
       }
-      printer.print("private static native \(caseName) $getAs\(caseName)(\(nativeParameters.joined(separator: ", ")));")
 
       printer.println()
     }

Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift

@@ -159,7 +159,8 @@ extension JNISwift2JavaGenerator {
     // Print getAsCase method
     if !enumCase.parameters.isEmpty {
       let selfParameter = JavaParameter(name: "self", type: .long)
-      let resultType = JavaType.class(package: javaPackage, name: "\(translatedCase.enumName).\(translatedCase.name)")
+
+      let resultType = JavaType.class(package: javaPackage, name: "\(translatedCase.enumName).\(translatedCase.name).$NativeParameters")
       printCDecl(
         &printer,
         javaMethodName: "$getAs\(translatedCase.name)",
@@ -176,15 +177,15 @@ extension JNISwift2JavaGenerator {
           parameter.name ?? "_\(idx)"
         }
         let caseNamesWithLet = caseNames.map { "let \($0)" }
-        let methodSignature = MethodSignature(resultType: resultType, parameterTypes: translatedCase.conversions.map(\.native.javaType))
+        let methodSignature = MethodSignature(resultType: .void, parameterTypes: translatedCase.conversions.map(\.native.javaType))
         // TODO: Caching of class and static method ID.
         printer.print(
         """
         guard case .\(enumCase.name)(\(caseNamesWithLet.joined(separator: ", "))) = \(selfPointer).pointee else {
           fatalError("Expected enum case '\(enumCase.name)', but was '\\(self$.pointee)'!")
         }
-        let recordClass$ = environment.interface.FindClass(environment, "\(javaPackagePath)/\(translatedCase.enumName)$\(translatedCase.name)")!
-        let fromJNIID$ = environment.interface.GetStaticMethodID(environment, recordClass$, "fromJNI", "\(methodSignature.mangledName)")!
+        let class$ = environment.interface.FindClass(environment, "\(javaPackagePath)/\(translatedCase.enumName)$\(translatedCase.name)$$NativeParameters")!
+        let constructorID$ = environment.interface.GetMethodID(environment, class$, "<init>", "\(methodSignature.mangledName)")!
         """
         )
 
@@ -197,7 +198,7 @@ extension JNISwift2JavaGenerator {
         printer.print(
           """
           return withVaList([\(upcallArguments.joined(separator: ", "))]) {
-            return environment.interface.CallStaticObjectMethodV(environment, recordClass$, fromJNIID$, $0)
+            return environment.interface.NewObjectV(environment, class$, constructorID$, $0)
           }
           """
         )