[JExtract] Import initializers as static methods

rintaro · rintaro · commit a8fa30224a87 · 2025-06-04T11:30:26.000-07:00
Preparation for importing failable initializers. Since Java 'new'
operator can't express 'nil' result from failable initializers importing
initializer as 'init' static method is a reasonable choice.
diff --git a/Samples/SwiftAndJavaJarSampleLib/src/jmh/java/org/swift/swiftkit/JavaToSwiftBenchmark.java b/Samples/SwiftAndJavaJarSampleLib/src/jmh/java/org/swift/swiftkit/JavaToSwiftBenchmark.java
@@ -45,7 +45,7 @@ public void beforeALl() {
             System.setProperty("jextract.trace.downcalls", "false");
 
             arena = SwiftArena.ofConfined();
-            obj = new MySwiftClass(1, 2, arena);
+            obj = MySwiftClass.init(1, 2, arena);
         }
 
         @TearDown(Level.Trial)
diff --git a/Samples/SwiftAndJavaJarSampleLib/src/main/java/com/example/swift/HelloJava2Swift.java b/Samples/SwiftAndJavaJarSampleLib/src/main/java/com/example/swift/HelloJava2Swift.java
@@ -44,7 +44,7 @@ static void examples() {
 
         // Example of using an arena; MyClass.deinit is run at end of scope
         try (var arena = SwiftArena.ofConfined()) {
-            MySwiftClass obj = new MySwiftClass(2222, 7777, arena);
+            MySwiftClass obj = MySwiftClass.init(2222, 7777, arena);
 
             // just checking retains/releases work
             SwiftKit.retain(obj);
diff --git a/Samples/SwiftAndJavaJarSampleLib/src/test/java/com/example/swift/MySwiftClassTest.java b/Samples/SwiftAndJavaJarSampleLib/src/test/java/com/example/swift/MySwiftClassTest.java
@@ -43,7 +43,7 @@ void checkPaths(Throwable throwable) {
     @Test
     void test_MySwiftClass_voidMethod() {
         try(var arena = SwiftArena.ofConfined()) {
-            MySwiftClass o = new MySwiftClass(12, 42, arena);
+            MySwiftClass o = MySwiftClass.init(12, 42, arena);
             o.voidMethod();
         } catch (Throwable throwable) {
             checkPaths(throwable);
@@ -53,7 +53,7 @@ void test_MySwiftClass_voidMethod() {
     @Test
     void test_MySwiftClass_makeIntMethod() {
         try(var arena = SwiftArena.ofConfined()) {
-            MySwiftClass o = new MySwiftClass(12, 42, arena);
+            MySwiftClass o = MySwiftClass.init(12, 42, arena);
             var got = o.makeIntMethod();
             assertEquals(12, got);
         }
@@ -63,7 +63,7 @@ void test_MySwiftClass_makeIntMethod() {
     @Disabled // TODO: Need var mangled names in interfaces
     void test_MySwiftClass_property_len() {
         try(var arena = SwiftArena.ofConfined()) {
-            MySwiftClass o = new MySwiftClass(12, 42, arena);
+            MySwiftClass o = MySwiftClass.init(12, 42, arena);
             var got = o.getLen();
             assertEquals(12, got);
         }
diff --git a/Samples/SwiftAndJavaJarSampleLib/src/test/java/org/swift/swiftkit/MySwiftClassTest.java b/Samples/SwiftAndJavaJarSampleLib/src/test/java/org/swift/swiftkit/MySwiftClassTest.java
@@ -25,7 +25,7 @@ public class MySwiftClassTest {
     @Test
     void call_retain_retainCount_release() {
         var arena = SwiftArena.ofConfined();
-        var obj = new MySwiftClass(1, 2, arena);
+        var obj = MySwiftClass.init(1, 2, arena);
 
         assertEquals(1, SwiftKit.retainCount(obj));
         // TODO: test directly on SwiftHeapObject inheriting obj
diff --git a/Samples/SwiftAndJavaJarSampleLib/src/test/java/org/swift/swiftkit/SwiftArenaTest.java b/Samples/SwiftAndJavaJarSampleLib/src/test/java/org/swift/swiftkit/SwiftArenaTest.java
@@ -39,7 +39,7 @@ static boolean isAmd64() {
     @DisabledIf("isAmd64")
     public void arena_releaseClassOnClose_class_ok() {
         try (var arena = SwiftArena.ofConfined()) {
-            var obj = new MySwiftClass(1, 2, arena);
+            var obj = MySwiftClass.init(1, 2, arena);
 
             retain(obj);
             assertEquals(2, retainCount(obj));
diff --git a/Samples/SwiftKitSampleApp/src/jmh/java/org/swift/swiftkit/JavaToSwiftBenchmark.java b/Samples/SwiftKitSampleApp/src/jmh/java/org/swift/swiftkit/JavaToSwiftBenchmark.java
@@ -37,7 +37,7 @@ public static class BenchmarkState {
         @Setup(Level.Trial)
         public void beforeAll() {
             arena = SwiftArena.ofConfined();
-            obj = new MySwiftClass(1, 2, arena);
+            obj = MySwiftClass.init(1, 2, arena);
         }
 
         @TearDown(Level.Trial)
diff --git a/Samples/SwiftKitSampleApp/src/jmh/java/org/swift/swiftkit/StringPassingBenchmark.java b/Samples/SwiftKitSampleApp/src/jmh/java/org/swift/swiftkit/StringPassingBenchmark.java
@@ -46,7 +46,7 @@ public class StringPassingBenchmark {
     @Setup(Level.Trial)
     public void beforeAll() {
         arena = SwiftArena.ofConfined();
-        obj = new MySwiftClass(1, 2, arena);
+        obj = MySwiftClass.init(1, 2, arena);
         string = makeString(stringLen);
     }
 
diff --git a/Samples/SwiftKitSampleApp/src/main/java/com/example/swift/HelloJava2Swift.java b/Samples/SwiftKitSampleApp/src/main/java/com/example/swift/HelloJava2Swift.java
@@ -47,7 +47,7 @@ static void examples() {
 
         // Example of using an arena; MyClass.deinit is run at end of scope
         try (var arena = SwiftArena.ofConfined()) {
-            MySwiftClass obj = new MySwiftClass(2222, 7777, arena);
+            MySwiftClass obj = MySwiftClass.init(2222, 7777, arena);
 
             // just checking retains/releases work
             SwiftKit.trace("retainCount = " + SwiftKit.retainCount(obj));
@@ -65,7 +65,7 @@ static void examples() {
             MySwiftClass otherObj = MySwiftClass.factory(12, 42, arena);
             otherObj.voidMethod();
 
-            MySwiftStruct swiftValue = new MySwiftStruct(2222, 1111, arena);
+            MySwiftStruct swiftValue = MySwiftStruct.init(2222, 1111, arena);
             SwiftKit.trace("swiftValue.capacity = " + swiftValue.getCapacity());
         }
 
diff --git a/Samples/SwiftKitSampleApp/src/test/java/com/example/swift/MySwiftClassTest.java b/Samples/SwiftKitSampleApp/src/test/java/com/example/swift/MySwiftClassTest.java
@@ -42,7 +42,7 @@ void checkPaths(Throwable throwable) {
     @Test
     void test_MySwiftClass_voidMethod() {
         try(var arena = SwiftArena.ofConfined()) {
-            MySwiftClass o = new MySwiftClass(12, 42, arena);
+            MySwiftClass o = MySwiftClass.init(12, 42, arena);
             o.voidMethod();
         } catch (Throwable throwable) {
             checkPaths(throwable);
@@ -52,7 +52,7 @@ void test_MySwiftClass_voidMethod() {
     @Test
     void test_MySwiftClass_makeIntMethod() {
         try(var arena = SwiftArena.ofConfined()) {
-            MySwiftClass o = new MySwiftClass(12, 42, arena);
+            MySwiftClass o = MySwiftClass.init(12, 42, arena);
             var got = o.makeIntMethod();
             assertEquals(12, got);
         }
@@ -62,7 +62,7 @@ void test_MySwiftClass_makeIntMethod() {
     @Disabled // TODO: Need var mangled names in interfaces
     void test_MySwiftClass_property_len() {
         try(var arena = SwiftArena.ofConfined()) {
-            MySwiftClass o = new MySwiftClass(12, 42, arena);
+            MySwiftClass o = MySwiftClass.init(12, 42, arena);
             var got = o.getLen();
             assertEquals(12, got);
         }
diff --git a/Samples/SwiftKitSampleApp/src/test/java/org/swift/swiftkit/MySwiftClassTest.java b/Samples/SwiftKitSampleApp/src/test/java/org/swift/swiftkit/MySwiftClassTest.java
@@ -25,7 +25,7 @@ public class MySwiftClassTest {
     @Test
     void call_retain_retainCount_release() {
         var arena = SwiftArena.ofConfined();
-        var obj = new MySwiftClass(1, 2, arena);
+        var obj = MySwiftClass.init(1, 2, arena);
 
         assertEquals(1, SwiftKit.retainCount(obj));
         // TODO: test directly on SwiftHeapObject inheriting obj
diff --git a/Samples/SwiftKitSampleApp/src/test/java/org/swift/swiftkit/MySwiftStructTest.java b/Samples/SwiftKitSampleApp/src/test/java/org/swift/swiftkit/MySwiftStructTest.java
@@ -26,7 +26,7 @@ void create_struct() {
         try (var arena = SwiftArena.ofConfined()) {
             long cap = 12;
             long len = 34;
-            var struct = new MySwiftStruct(cap, len, arena);
+            var struct = MySwiftStruct.init(cap, len, arena);
 
             assertEquals(cap, struct.getCapacity());
             assertEquals(len, struct.getLength());
diff --git a/Samples/SwiftKitSampleApp/src/test/java/org/swift/swiftkit/SwiftArenaTest.java b/Samples/SwiftKitSampleApp/src/test/java/org/swift/swiftkit/SwiftArenaTest.java
@@ -40,7 +40,7 @@ static boolean isAmd64() {
     @DisabledIf("isAmd64")
     public void arena_releaseClassOnClose_class_ok() {
         try (var arena = SwiftArena.ofConfined()) {
-            var obj = new MySwiftClass(1, 2, arena);
+            var obj = MySwiftClass.init(1, 2, arena);
 
             retain(obj);
             assertEquals(2, retainCount(obj));
@@ -57,7 +57,7 @@ public void arena_markAsDestroyed_preventUseAfterFree_class() {
         MySwiftClass unsafelyEscapedOutsideArenaScope = null;
 
         try (var arena = SwiftArena.ofConfined()) {
-            var obj = new MySwiftClass(1, 2, arena);
+            var obj = MySwiftClass.init(1, 2, arena);
             unsafelyEscapedOutsideArenaScope = obj;
         }
 
@@ -76,7 +76,7 @@ public void arena_markAsDestroyed_preventUseAfterFree_struct() {
         MySwiftStruct unsafelyEscapedOutsideArenaScope = null;
 
         try (var arena = SwiftArena.ofConfined()) {
-            var s = new MySwiftStruct(1, 2, arena);
+            var s = MySwiftStruct.init(1, 2, arena);
             unsafelyEscapedOutsideArenaScope = s;
         }
 
diff --git a/Sources/JExtractSwift/Swift2JavaTranslator+JavaBindingsPrinting.swift b/Sources/JExtractSwift/Swift2JavaTranslator+JavaBindingsPrinting.swift
@@ -15,18 +15,6 @@
 import JavaTypes
 
 extension Swift2JavaTranslator {
-  public func printInitializerDowncallConstructors(
-    _ printer: inout CodePrinter,
-    _ decl: ImportedFunc
-  ) {
-    printer.printSeparator(decl.displayName)
-
-    printJavaBindingDescriptorClass(&printer, decl)
-
-    // Render the "make the downcall" functions.
-    printInitializerDowncallConstructor(&printer, decl)
-  }
-
   public func printFunctionDowncallMethods(
     _ printer: inout CodePrinter,
     _ decl: ImportedFunc
@@ -86,43 +74,6 @@ extension Swift2JavaTranslator {
     printer.print(");")
   }
 
-  public func printInitializerDowncallConstructor(
-    _ printer: inout CodePrinter,
-    _ decl: ImportedFunc
-  ) {
-    guard let className = decl.parentType?.asNominalTypeDeclaration?.name else {
-      return
-    }
-    let modifiers = "public"
-
-    var paramDecls = decl.translatedSignature.parameters
-      .flatMap(\.javaParameters)
-      .map { "\($0.type) \($0.name)" }
-
-    assert(decl.translatedSignature.requiresSwiftArena, "constructor always require the SwiftArena")
-    paramDecls.append("SwiftArena swiftArena$")
-
-    printer.printBraceBlock(
-      """
-      /**
-       * Create an instance of {@code \(className)}.
-       *
-       * {@snippet lang=swift :
-       * \(decl.signatureString)
-       * }
-       */
-      \(modifiers) \(className)(\(paramDecls.joined(separator: ", ")))
-      """
-    ) { printer in
-      // Call super constructor `SwiftValue(Supplier <MemorySegment>, SwiftArena)`.
-      printer.print("super(() -> {")
-      printer.indent()
-      printDowncall(&printer, decl, isConstructor: true)
-      printer.outdent()
-      printer.print("}, swiftArena$);")
-    }
-  }
-
   /// Print the calling body that forwards all the parameters to the `methodName`,
   /// with adding `SwiftArena.ofAuto()` at the end.
   public func printFuncDowncallMethod(
@@ -131,13 +82,12 @@ extension Swift2JavaTranslator {
     let methodName: String = switch decl.kind {
     case .getter: "get\(decl.name.toCamelCase)"
     case .setter: "set\(decl.name.toCamelCase)"
-    case .function: decl.name
-    case .initializer: fatalError("initializers must use printInitializerDowncallConstructor()")
+    case .function, .initializer: decl.name
     }
 
     var modifiers = "public"
     switch decl.swiftSignature.selfParameter {
-    case .staticMethod(_), nil:
+    case .staticMethod, .initializer, nil:
       modifiers.append(" static")
     default:
       break
@@ -178,8 +128,7 @@ extension Swift2JavaTranslator {
   /// This assumes that all the parameters are passed-in with appropriate names.
   package func printDowncall(
     _ printer: inout CodePrinter,
-    _ decl: ImportedFunc,
-    isConstructor: Bool = false
+    _ decl: ImportedFunc
   ) {
     //===  Part 1: MethodHandle
     let descriptorClassIdentifier = thunkNameRegistry.functionThunkName(decl: decl)
@@ -252,11 +201,7 @@ extension Swift2JavaTranslator {
     let downCall = "mh$.invokeExact(\(downCallArguments.joined(separator: ", ")))"
 
     //=== Part 4: Convert the return value.
-    if isConstructor {
-      // For constructors, the caller expects the "self" memory segment.
-      printer.print("\(downCall);")
-      printer.print("return _result;")
-    } else if decl.translatedSignature.result.javaResultType == .void {
+    if decl.translatedSignature.result.javaResultType == .void {
       printer.print("\(downCall);")
     } else {
       let placeholder: String
diff --git a/Sources/JExtractSwift/Swift2JavaTranslator+Printing.swift b/Sources/JExtractSwift/Swift2JavaTranslator+Printing.swift
@@ -125,7 +125,7 @@ extension Swift2JavaTranslator {
 
       // Initializers
       for initDecl in decl.initializers {
-        printInitializerDowncallConstructors(&printer, initDecl)
+        printFunctionDowncallMethods(&printer, initDecl)
       }
 
       // Properties
diff --git a/SwiftKit/src/main/java/org/swift/swiftkit/SwiftInstance.java b/SwiftKit/src/main/java/org/swift/swiftkit/SwiftInstance.java
@@ -66,19 +66,6 @@ protected SwiftInstance(MemorySegment segment, SwiftArena arena) {
         arena.register(this);
     }
 
-    /**
-     * Convenience constructor subclasses can call like:
-     * {@snippet :
-     * super(() -> { ...; return segment; }, swiftArena$)
-     * }
-     *
-     * @param segmentSupplier Should return the memory segment of the value
-     * @param arena the arena where the supplied segment belongs to. When the arena goes out of scope, this value is destroyed.
-     */
-    protected SwiftInstance(Supplier<MemorySegment> segmentSupplier, SwiftArena arena) {
-        this(segmentSupplier.get(), arena);
-    }
-
     /**
      * Ensures that this instance has not been destroyed.
      * <p/>
diff --git a/Tests/JExtractSwiftTests/MethodImportTests.swift b/Tests/JExtractSwiftTests/MethodImportTests.swift
@@ -334,34 +334,31 @@ final class MethodImportTests {
     }!
 
     let output = CodePrinter.toString { printer in
-      st.printInitializerDowncallConstructor(&printer, initDecl)
+      st.printFuncDowncallMethod(&printer, initDecl)
     }
 
     assertOutput(
       output,
       expected:
         """
         /**
-         * Create an instance of {@code MySwiftClass}.
-         *
+         * Downcall to Swift:
          * {@snippet lang=swift :
          * public init(len: Swift.Int, cap: Swift.Int)
          * }
          */
-        public MySwiftClass(long len, long cap, SwiftArena swiftArena$) {
-          super(() -> {
-            var mh$ = swiftjava___FakeModule_MySwiftClass_init_len_cap.HANDLE;
-            try {
-              MemorySegment _result = swiftArena$.allocate(MySwiftClass.$LAYOUT);
-              if (SwiftKit.TRACE_DOWNCALLS) {
-                  SwiftKit.traceDowncall(len, cap, _result);
-              }
-              mh$.invokeExact(len, cap, _result);
-              return _result;
-            } catch (Throwable ex$) {
-                throw new AssertionError("should not reach here", ex$);
+        public static MySwiftClass init(long len, long cap, SwiftArena swiftArena$) {
+          var mh$ = swiftjava___FakeModule_MySwiftClass_init_len_cap.HANDLE;
+          try {
+            MemorySegment _result = swiftArena$.allocate(MySwiftClass.$LAYOUT);
+            if (SwiftKit.TRACE_DOWNCALLS) {
+                SwiftKit.traceDowncall(len, cap, _result);
             }
-          }, swiftArena$);
+            mh$.invokeExact(len, cap, _result);
+            return new MySwiftClass(_result, swiftArena$);
+          } catch (Throwable ex$) {
+              throw new AssertionError("should not reach here", ex$);
+          }
         }
         """
     )
@@ -382,34 +379,31 @@ final class MethodImportTests {
     }!
 
     let output = CodePrinter.toString { printer in
-      st.printInitializerDowncallConstructor(&printer, initDecl)
+      st.printFuncDowncallMethod(&printer, initDecl)
     }
 
     assertOutput(
       output,
       expected:
         """
         /**
-         * Create an instance of {@code MySwiftStruct}.
-         *
+         * Downcall to Swift:
          * {@snippet lang=swift :
          * public init(len: Swift.Int, cap: Swift.Int)
          * }
          */
-        public MySwiftStruct(long len, long cap, SwiftArena swiftArena$) {
-          super(() -> {
-            var mh$ = swiftjava___FakeModule_MySwiftStruct_init_len_cap.HANDLE;
-            try {
-              MemorySegment _result = swiftArena$.allocate(MySwiftStruct.$LAYOUT);
-              if (SwiftKit.TRACE_DOWNCALLS) {
+        public static MySwiftStruct init(long len, long cap, SwiftArena swiftArena$) {
+          var mh$ = swiftjava___FakeModule_MySwiftStruct_init_len_cap.HANDLE;
+          try {
+            MemorySegment _result = swiftArena$.allocate(MySwiftStruct.$LAYOUT);
+            if (SwiftKit.TRACE_DOWNCALLS) {
                 SwiftKit.traceDowncall(len, cap, _result);
-              }
-              mh$.invokeExact(len, cap, _result);
-              return _result;
-            } catch (Throwable ex$) {
-                throw new AssertionError("should not reach here", ex$);
             }
-          }, swiftArena$);
+            mh$.invokeExact(len, cap, _result);
+            return new MySwiftStruct(_result, swiftArena$);
+          } catch (Throwable ex$) {
+            throw new AssertionError("should not reach here", ex$);
+          }
         }
         """
     )

Original file line number	Diff line number	Diff line change
`@@ -45,7 +45,7 @@ public void beforeALl() {`
`45`	`45`	`System.setProperty("jextract.trace.downcalls", "false");`
`46`	`46`
`47`	`47`	`arena = SwiftArena.ofConfined();`
`48`		`- obj = new MySwiftClass(1, 2, arena);`
	`48`	`+ obj = MySwiftClass.init(1, 2, arena);`
`49`	`49`	`}`
`50`	`50`
`51`	`51`	`@TearDown(Level.Trial)`
Original file line number	Diff line number	Diff line change
`@@ -37,7 +37,7 @@ public static class BenchmarkState {`
`37`	`37`	`@Setup(Level.Trial)`
`38`	`38`	`public void beforeAll() {`
`39`	`39`	`arena = SwiftArena.ofConfined();`
`40`		`- obj = new MySwiftClass(1, 2, arena);`
	`40`	`+ obj = MySwiftClass.init(1, 2, arena);`
`41`	`41`	`}`
`42`	`42`
`43`	`43`	`@TearDown(Level.Trial)`
Original file line number	Diff line number	Diff line change
`@@ -46,7 +46,7 @@ public class StringPassingBenchmark {`
`46`	`46`	`@Setup(Level.Trial)`
`47`	`47`	`public void beforeAll() {`
`48`	`48`	`arena = SwiftArena.ofConfined();`
`49`		`- obj = new MySwiftClass(1, 2, arena);`
	`49`	`+ obj = MySwiftClass.init(1, 2, arena);`
`50`	`50`	`string = makeString(stringLen);`
`51`	`51`	`}`
`52`	`52`