jextract import optional types

Samples/SwiftKitSampleApp/src/test/java/com/example/swift/generated/MySwiftClassTest.java

@@ -20,6 +20,8 @@
 import org.junit.jupiter.api.condition.DisabledOnOs;
 import org.junit.jupiter.api.condition.OS;
 
+import java.util.OptionalLong;
+
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 
@@ -56,4 +58,11 @@ void test_MySwiftClass_property_len() {
         assertEquals(12, got);
     }
 
+    @Test
+    void test_MySwiftClass_optionalInt() {
+        MySwiftClass o = new MySwiftClass(12, 42);
+        OptionalLong got = o.getOptionalInt(); // FIXME: we need to get the Swift optional as memory region, map it to the Java Optional
+        assertEquals(12, got);
+    }
+
 }

Sources/ExampleSwiftLibrary/MySwiftLibrary.swift

@@ -78,6 +78,10 @@ public class MySwiftClass {
     p("make int -> 12")
     return 12
   }
+
+  public func getOptionalInt() -> Int? {
+    return 12
+  }
 }
 
 @_silgen_name("swift_getTypeByMangledNameInEnvironment")

Sources/JExtractSwift/JavaTypes.swift

@@ -25,3 +25,51 @@ extension JavaType {
     .class(package: "java.lang", name: "Runnable")
   }
 }
+
+// ==== ------------------------------------------------------------------------
+// Optionals
+
+extension JavaType {
+
+  static var javaUtilOptionalInt: JavaType {
+    .class(package: "java.util", name: "OptionalInt")
+  }
+
+  static var javaUtilOptionalLong: JavaType {
+    .class(package: "java.util", name: "OptionalLong")
+  }
+
+  static var javaUtilOptionalDouble: JavaType {
+    .class(package: "java.util", name: "OptionalDouble")
+  }
+
+  // FIXME: general generics?
+  static func javaUtilOptionalT(_ javaType: JavaType) -> JavaType {
+    if let className = javaType.className {
+      return .class(package: "java.util", name: "Optional<\(className)>")
+    }
+
+    if javaType.isPrimitive {
+      switch javaType {
+      case .int, .long:
+        return .javaUtilOptionalLong
+      case .float, .double:
+        return .javaUtilOptionalDouble
+      case .boolean:
+        return .class(package: "java.util", name: "Optional<Boolean>")
+      case .byte:
+        return .class(package: "java.util", name: "Optional<Byte>")
+      case .char:
+        return .class(package: "java.util", name: "Optional<Character>")
+      case .short:
+        return .class(package: "java.util", name: "Optional<Short>")
+      case .void:
+        return .class(package: "java.util", name: "Optional<Void>")
+      default:
+        fatalError("Impossible type to map to Optional: \(javaType)")
+      }
+    }
+
+    fatalError("Impossible type to map to Optional: \(javaType)")
+  }
+}

Sources/JExtractSwift/Swift2JavaTranslator+Printing.swift

@@ -31,7 +31,7 @@ extension Swift2JavaTranslator {
     for (_, ty) in importedTypes.sorted(by: { (lhs, rhs) in lhs.key < rhs.key }) {
       let filename = "\(ty.javaClassName).java"
       log.info("Printing contents: \(filename)")
-      printImportedClass(&printer, ty)
+      printImportedNominalType(&printer, ty)
 
       try writeContents(
         printer.finalize(),
@@ -110,7 +110,7 @@ extension Swift2JavaTranslator {
     }
   }
 
-  public func printImportedClass(_ printer: inout CodePrinter, _ decl: ImportedNominalType) {
+  public func printImportedNominalType(_ printer: inout CodePrinter, _ decl: ImportedNominalType) {
     printHeader(&printer)
     printPackage(&printer)
     printImports(&printer)
@@ -152,7 +152,6 @@ extension Swift2JavaTranslator {
   }
 
   public func printHeader(_ printer: inout CodePrinter) {
-    assert(printer.isEmpty)
     printer.print(
       """
       // Generated by jextract-swift
@@ -457,7 +456,8 @@ extension Swift2JavaTranslator {
     printer.print(
       """
       static {
-          System.loadLibrary("swiftCore");
+          System.loadLibrary(SwiftKit.STDLIB_DYLIB_NAME);
+          System.loadLibrary(SwiftKit.SWIFTKIT_DYLIB_NAME);
           System.loadLibrary(LIB_NAME);
       }
       """

Sources/JExtractSwift/Swift2JavaVisitor.swift

@@ -100,6 +100,7 @@ final class Swift2JavaVisitor: SyntaxVisitor {
       }
 
       javaResultType = try cCompatibleType(for: returnTy)
+      log.trace("Mapped return type type: \(returnTy) -> \(javaResultType)")
     } catch {
       self.log.info("Unable to import function \(node.name) - \(error)")
       return .skipChildren

Sources/JExtractSwift/TranslatedType.swift

@@ -23,10 +23,30 @@ extension Swift2JavaVisitor {
     case .arrayType, .attributedType, .classRestrictionType, .compositionType,
         .dictionaryType, .implicitlyUnwrappedOptionalType, .metatypeType,
         .missingType, .namedOpaqueReturnType,
-        .optionalType, .packElementType, .packExpansionType, .someOrAnyType,
+        .packElementType, .packExpansionType, .someOrAnyType,
         .suppressedType, .tupleType:
       throw TypeTranslationError.unimplementedType(type)
 
+    case .optionalType(let optionalType):
+      if optionalType.wrappedType.trimmedDescription == "Int" {
+        return TranslatedType(
+          cCompatibleConvention: .direct,
+          originalSwiftType: optionalType.wrappedType, // FIXME: just optionalType?
+          cCompatibleSwiftType: "OptionalLong",
+          cCompatibleJavaMemoryLayout: .heapObject,
+          javaType: .javaUtilOptionalLong
+        )
+      } else if let translatedWrappedType = try? cCompatibleType(for: optionalType.wrappedType) {
+        return TranslatedType(
+          cCompatibleConvention: .direct,
+          originalSwiftType: optionalType.wrappedType, // FIXME: just optionalType?
+          cCompatibleSwiftType: "Optional<TODO>",
+          cCompatibleJavaMemoryLayout: .heapObject,
+          javaType: .javaUtilOptionalT(translatedWrappedType.javaType)
+        )
+      } else {
+        throw TypeTranslationError.unimplementedType(type)
+      }
     case .functionType(let functionType):
       // FIXME: Temporary hack to keep existing code paths working.
       if functionType.trimmedDescription == "() -> ()" {

SwiftKit/src/main/java/org/swift/swiftkit/SwiftKit.java

@@ -27,15 +27,17 @@
 
 public class SwiftKit {
 
-    private static final String STDLIB_DYLIB_NAME = "swiftCore";
-    private static final String STDLIB_MACOS_DYLIB_PATH = "/usr/lib/swift/libswiftCore.dylib";
+    public static final String STDLIB_DYLIB_NAME = "swiftCore";
+    public static final String SWIFTKIT_DYLIB_NAME = "SwiftKitSwift";
 
-    private static final Arena LIBRARY_ARENA = Arena.ofAuto();
+    static final String STDLIB_MACOS_DYLIB_PATH = "/usr/lib/swift/libswiftCore.dylib";
+
+    static final Arena LIBRARY_ARENA = Arena.ofAuto();
     static final boolean TRACE_DOWNCALLS = Boolean.getBoolean("jextract.trace.downcalls");
 
     static {
         System.loadLibrary(STDLIB_DYLIB_NAME);
-        System.loadLibrary("SwiftKitSwift");
+        System.loadLibrary(SWIFTKIT_DYLIB_NAME);
     }
 
     static final SymbolLookup SYMBOL_LOOKUP = getSymbolLookup();

SwiftKit/src/main/java/org/swift/swiftkit/stdlib/SwiftOptional.java

@@ -0,0 +1,57 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package org.swift.swiftkit.stdlib;
+
+import org.swift.swiftkit.*;
+import org.swift.swiftkit.util.TypeToken;
+
+import java.lang.foreign.*;
+
+public class SwiftOptional<Wrapped extends SwiftInstance> implements SwiftValue {
+
+    // Pointer to the referred to class instance's "self".
+    private final MemorySegment selfMemorySegment;
+
+    static final String LIB_NAME = SwiftKit.STDLIB_DYLIB_NAME;
+
+    public SwiftOptional(MemorySegment selfMemorySegment) {
+        this.selfMemorySegment = selfMemorySegment;
+    }
+
+    public final MemorySegment $memorySegment() {
+        return this.selfMemorySegment;
+    }
+
+    public static final AddressLayout SWIFT_POINTER = ValueLayout.ADDRESS;
+
+    private static final GroupLayout $LAYOUT = MemoryLayout.structLayout(
+            SWIFT_POINTER
+    ).withName("Swift.Optional<T>");
+
+    @Override
+    public GroupLayout $layout() {
+        return $LAYOUT;
+    }
+
+    @Override
+    public SwiftAnyType $swiftType() {
+        var ty = new TypeToken<Wrapped>() {}.getType();
+        if (ty == Integer.class || ty == Long.class) {
+            return SwiftKit.getTypeByMangledNameInEnvironment("SiSg").get();
+        } else {
+            throw new RuntimeException("Other Optional type mappings not implemented yet");
+        }
+    }
+}

SwiftKit/src/main/java/org/swift/swiftkit/util/TypeToken.java

@@ -0,0 +1,35 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package org.swift.swiftkit.util;
+
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+
+/**
+ * Type token to obtain the underlying {@link Type} of a generic type {@code T}.
+ * @param <T>
+ */
+public abstract class TypeToken<T> {
+    private Type type;
+
+    protected TypeToken(){
+        Type superClass = getClass().getGenericSuperclass();
+        this.type = ((ParameterizedType) superClass).getActualTypeArguments()[0];
+    }
+
+    public Type getType() {
+        return type;
+    }
+}

SwiftKit/src/test/java/org/swift/swiftkit/util/TypeTokenTest.java

@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package org.swift.swiftkit.util;
+
+import org.junit.jupiter.api.Test;
+
+import java.lang.reflect.Type;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class TypeTokenTest {
+    @Test
+    void token() {
+        var token = new TypeToken<String>() {};
+        Type type = token.getType();
+        assertEquals(String.class, type);
+    }
+}