Tweak

Author: rintaro

Samples/SwiftKitSampleApp/src/test/java/com/example/swift/MySwiftLibraryTest.java

@@ -64,9 +64,11 @@ void call_writeString_jni() {
     void call_globalCallMeRunnable() {
         CountDownLatch countDownLatch = new CountDownLatch(3);
 
-        MySwiftLibrary.globalCallMeRunnable.run fn = () -> {};
-        MySwiftLibrary.globalCallMeRunnable(() -> {
-            countDownLatch.countDown();
+        MySwiftLibrary.globalCallMeRunnable(new MySwiftLibrary.globalCallMeRunnable.run() {
+            @Override
+            public void apply() {
+                countDownLatch.countDown();
+            }
         });
         assertEquals(2, countDownLatch.getCount());
 

Sources/JExtractSwift/CDeclLowering/Swift2JavaTranslator+FunctionLowering.swift

@@ -116,7 +116,7 @@ struct CdeclLowering {
     )
   }
 
-  /// Lower a Swift function parameter type to cdecl parameters.
+  /// Lower a Swift function parameter to cdecl parameters.
   ///
   /// For example, Swift parameter `arg value: inout Int` can be lowered with
   /// `lowerParameter(intTy, .inout, "value")`.
@@ -294,6 +294,10 @@ struct CdeclLowering {
     }
   }
 
+  /// Lower a Swift function type (i.e. closure) to cdecl function type.
+  ///
+  /// - Parameters:
+  ///   - fn: the Swift function type to lower.
   func lowerFunctionType(
     _ fn: SwiftFunctionType
   ) throws -> (type: SwiftType, conversion: ConversionStep) {

Sources/JExtractSwift/Swift2JavaTranslator+JavaBindingsPrinting.swift

@@ -128,6 +128,10 @@ extension Swift2JavaTranslator {
     )
   }
 
+  /// Print required helper classes/interfaces for describing the CFunction.
+  ///
+  /// * function pointer parameter as a function interface.
+  /// * Unnamed-struct parameter as a record. (unimplemented)
   func printParameterDescriptorClasses(
     _ printer: inout CodePrinter,
     _ cFunc: CFunction
@@ -143,13 +147,14 @@ extension Swift2JavaTranslator {
     }
   }
 
-  /// Print a class describing a closure parameter type.
-  ///   ```
-  ///   class <paramter-name> {
+  /// Print a class describing a function pointer parameter type.
+  ///
+  ///   ```java
+  ///   class $<parameter-name> {
   ///     interface Function {
   ///       <return-type> apply(<parameters>);
   ///     }
-  ///     static final MethodDescriptor DESC = FunctionDescriptor.of(...);s
+  ///     static final MethodDescriptor DESC = FunctionDescriptor.of(...);
   ///     static final MethodHandle HANDLE = SwiftKit.upcallHandle(Function.class, "apply", DESC);
   ///     static MemorySegment toUpcallStub(Function fi, Arena arena) {
   ///       return Linker.nativeLinker().upcallStub(HANDLE.bindTo(fi), DESC, arena);
@@ -199,6 +204,9 @@ extension Swift2JavaTranslator {
     }
   }
 
+  /// Print the helper type container for a user-facing Java API.
+  ///
+  /// * User-facing function interfaces.
   func printJavaBindingWrapperHelperClass(
     _ printer: inout CodePrinter,
     _ decl: ImportedFunc
@@ -220,13 +228,16 @@ extension Swift2JavaTranslator {
     }
   }
 
+  /// Print "wrapper" function interface representing a Swift closure type.
   func printJavaBindingWrapperFunctionTypeHelper(
     _ printer: inout CodePrinter,
     _ functionType: TranslatedFunctionType,
     _ bindingDescriptorName: String
   ) {
     let cdeclDescritor = "\(bindingDescriptorName).$\(functionType.name)"
     if functionType.isTrivial {
+      // If the usser-facing function interface is C-compatible, just extend the
+      // lowered function pointer parameter interface.
       printer.print(
         """
         public interface \(functionType.name) extends \(cdeclDescritor).Function {
@@ -237,6 +248,7 @@ extension Swift2JavaTranslator {
         """
       )
     } else {
+      // Otherwise, the lambda must be wrapped with the lowered function instance.
       assertionFailure("should be unreachable at this point")
       let apiParams = functionType.parameters.flatMap {
         $0.javaParameters.map { param in "\(param.type) \(param.name)" }

Sources/JExtractSwift/Swift2JavaTranslator+JavaTranslation.swift

@@ -24,7 +24,8 @@ extension Swift2JavaTranslator {
 
     let translated: TranslatedFunctionDecl?
     do {
-      translated = try self.translate(decl)
+      let translation = JavaTranslation(swiftStdlibTypes: self.swiftStdlibTypes)
+      translated = try translation.translate(decl)
     } catch {
       self.log.info("Failed to translate: '\(decl.swiftDecl.qualifiedNameForDebug)'; \(error)")
       translated = nil
@@ -33,11 +34,6 @@ extension Swift2JavaTranslator {
     translatedDecls[decl] = translated
     return translated
   }
-
-  private func translate(_ decl: ImportedFunc) throws -> TranslatedFunctionDecl {
-    let translation = JavaTranslation(swiftStdlibTypes: self.swiftStdlibTypes)
-    return try translation.translate(decl)
-  }
 }
 
 /// Represent a parameter in Java code.
@@ -83,18 +79,27 @@ struct TranslatedResult {
   var conversion: JavaConversionStep
 }
 
+
+/// Translated Java API representing a Swift API.
+///
+/// Since this holds the lowered signature, and the original `SwiftFunctionSignature`
+/// in it, this contains all the API information (except the name) to generate the
+/// cdecl thunk, Java binding, and the Java wrapper function.
 struct TranslatedFunctionDecl {
+  /// Java function name.
   let name: String
+
+  /// Function interfaces (i.e. lambda types) required for the Java method.
   let functionTypes: [TranslatedFunctionType]
+
+  /// Function signature.
   let translatedSignature: TranslatedFunctionSignature
+
+  /// Cdecl lowerd signature.
   let loweredSignature: LoweredFunctionSignature
 }
 
-/// Translated function signature representing a Swift API.
-///
-/// Since this holds the lowered signature, and the original `SwiftFunctionSignature`
-/// in it, this contains all the API information (except the name) to generate the
-/// cdecl thunk, Java binding, and the Java wrapper function.
+/// Function signature for a Java API.
 struct TranslatedFunctionSignature {
   var selfParameter: TranslatedParameter?
   var parameters: [TranslatedParameter]
@@ -219,7 +224,7 @@ struct JavaTranslation {
     )
   }
 
-  /// Translate Swift API to user-facing Java API.
+  /// Translate a Swift API signature to the user-facing Java API signature.
   ///
   /// Note that the result signature is for the high-level Java API, not the
   /// low-level FFM down-calling interface.
@@ -268,7 +273,7 @@ struct JavaTranslation {
     )
   }
 
-  /// Translate
+  /// Translate a Swift API parameter to the user-facing Java API parameter.
   func translate(
     swiftParam: SwiftParameter,
     loweredParam: LoweredParameter,
@@ -368,6 +373,7 @@ struct JavaTranslation {
     }
   }
 
+  /// Translate a Swift API result to the user-facing Java API result.
   func translate(
     swiftResult: SwiftResult,
     loweredResult: LoweredResult