Introduce protocol-based structure for generating code

.editorconfig

@@ -0,0 +1,6 @@
+root = true
+
+[*.swift]
+indent_style = space
+indent_size = 2
+insert_final_newline = true

Sources/JExtractSwiftLib/AnalysisResult.swift

@@ -0,0 +1,19 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 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
+//
+//===----------------------------------------------------------------------===//
+
+struct AnalysisResult {
+  let importedTypes: [String: ImportedNominalType]
+  let importedGlobalVariables: [ImportedFunc]
+  let importedGlobalFuncs: [ImportedFunc]
+}

Sources/JExtractSwiftLib/CodePrinter.swift

@@ -14,6 +14,8 @@
 
 import Foundation
 
+let PATH_SEPARATOR = "/"  // TODO: Windows
+
 public struct CodePrinter {
   var contents: String = ""
 

Sources/JExtractSwiftLib/CDeclLowering/Swift2JavaTranslator+FunctionLowering.swift → Sources/JExtractSwiftLib/FFM/CDeclLowering/FFMSwift2JavaGenerator+FunctionLowering.swift

@@ -15,7 +15,7 @@
 import JavaTypes
 import SwiftSyntax
 
-extension Swift2JavaTranslator {
+extension FFMSwift2JavaGenerator {
   /// Lower the given function declaration to a C-compatible entrypoint,
   /// providing all of the mappings between the parameter and result types
   /// of the original function and its `@_cdecl` counterpart.

Sources/JExtractSwiftLib/Swift2JavaTranslator+JavaBindingsPrinting.swift → Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaBindingsPrinting.swift

@@ -14,8 +14,8 @@
 
 import JavaTypes
 
-extension Swift2JavaTranslator {
-  public func printFunctionDowncallMethods(
+extension FFMSwift2JavaGenerator {
+  func printFunctionDowncallMethods(
     _ printer: inout CodePrinter,
     _ decl: ImportedFunc
   ) {
@@ -211,7 +211,7 @@ extension Swift2JavaTranslator {
       let memoryLayout = renderMemoryLayoutValue(for: outParameter.type)
 
       let arena = if let className = outParameter.type.className,
-         self.importedTypes[className] != nil {
+         analysis.importedTypes[className] != nil {
         // Use passed-in 'SwiftArena' for 'SwiftValue'.
         "swiftArena$"
       } else {

Sources/JExtractSwiftLib/Swift2JavaTranslator+JavaTranslation.swift → Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaTranslation.swift

@@ -14,7 +14,7 @@
 
 import JavaTypes
 
-extension Swift2JavaTranslator {
+extension FFMSwift2JavaGenerator {
   func translatedSignature(
     for decl: ImportedFunc
   ) -> TranslatedFunctionSignature? {

Sources/JExtractSwiftLib/Swift2JavaTranslator+SwiftThunkPrinting.swift → Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+SwiftThunkPrinting.swift

@@ -15,14 +15,13 @@
 import SwiftSyntax
 import SwiftSyntaxBuilder
 
-extension Swift2JavaTranslator {
-  public func writeSwiftThunkSources(outputDirectory: String) throws {
+extension FFMSwift2JavaGenerator {
+  package func writeSwiftThunkSources() throws {
     var printer = CodePrinter()
-
-    try writeSwiftThunkSources(outputDirectory: outputDirectory, printer: &printer)
+    try writeSwiftThunkSources(printer: &printer)
   }
 
-  public func writeSwiftThunkSources(outputDirectory: String, printer: inout CodePrinter) throws {
+  package func writeSwiftThunkSources(printer: inout CodePrinter) throws {
     let moduleFilenameBase = "\(self.swiftModuleName)Module+SwiftJava"
     let moduleFilename = "\(moduleFilenameBase).swift"
     do {
@@ -31,7 +30,7 @@ extension Swift2JavaTranslator {
       try printGlobalSwiftThunkSources(&printer)
 
       if let outputFile = try printer.writeContents(
-        outputDirectory: outputDirectory,
+        outputDirectory: self.swiftOutputDirectory,
         javaPackagePath: nil,
         filename: moduleFilename)
       {
@@ -42,7 +41,7 @@ extension Swift2JavaTranslator {
     }
 
     // === All types
-    for (_, ty) in importedTypes.sorted(by: { (lhs, rhs) in lhs.key < rhs.key }) {
+    for (_, ty) in self.analysis.importedTypes.sorted(by: { (lhs, rhs) in lhs.key < rhs.key }) {
       let fileNameBase = "\(ty.swiftNominal.qualifiedName)+SwiftJava"
       let filename = "\(fileNameBase).swift"
       log.info("Printing contents: \(filename)")
@@ -51,7 +50,7 @@ extension Swift2JavaTranslator {
         try printSwiftThunkSources(&printer, ty: ty)
 
         if let outputFile = try printer.writeContents(
-          outputDirectory: outputDirectory,
+          outputDirectory: self.swiftOutputDirectory,
           javaPackagePath: nil,
           filename: filename)
         {
@@ -110,23 +109,23 @@ extension Swift2JavaTranslator {
 
 struct SwiftThunkTranslator {
 
-  let st: Swift2JavaTranslator
+  let st: FFMSwift2JavaGenerator
 
-  init(_ st: Swift2JavaTranslator) {
+  init(_ st: FFMSwift2JavaGenerator) {
     self.st = st
   }
 
   func renderGlobalThunks() -> [DeclSyntax] {
     var decls: [DeclSyntax] = []
     decls.reserveCapacity(
-      st.importedGlobalVariables.count + st.importedGlobalFuncs.count
+      st.analysis.importedGlobalVariables.count + st.analysis.importedGlobalFuncs.count
     )
 
-    for decl in st.importedGlobalVariables {
+    for decl in st.analysis.importedGlobalVariables {
       decls.append(contentsOf: render(forFunc: decl))
     }
 
-    for decl in st.importedGlobalFuncs {
+    for decl in st.analysis.importedGlobalFuncs {
       decls.append(contentsOf: render(forFunc: decl))
     }
 

Sources/JExtractSwiftLib/Swift2JavaTranslator+Printing.swift → Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator.swift

@@ -16,27 +16,90 @@ import JavaTypes
 import SwiftSyntax
 import SwiftSyntaxBuilder
 
+package class FFMSwift2JavaGenerator: Swift2JavaGenerator {
+  let log: Logger
+  let analysis: AnalysisResult
+  let swiftModuleName: String
+  let javaPackage: String
+  let swiftOutputDirectory: String
+  let javaOutputDirectory: String
+  let swiftStdlibTypes: SwiftStandardLibraryTypes
+  let symbolTable: SwiftSymbolTable
+
+  var javaPackagePath: String {
+    javaPackage.replacingOccurrences(of: ".", with: "/")
+  }
+
+  var thunkNameRegistry: ThunkNameRegistry = ThunkNameRegistry()
+
+  /// Cached Java translation result. 'nil' indicates failed translation.
+  var translatedSignatures: [ImportedFunc: TranslatedFunctionSignature?] = [:]
+
+  package init(
+    translator: Swift2JavaTranslator,
+    javaPackage: String,
+    swiftOutputDirectory: String,
+    javaOutputDirectory: String
+  ) {
+    self.log = Logger(label: "ffm-generator", logLevel: translator.log.logLevel)
+    self.analysis = translator.result
+    self.swiftModuleName = translator.swiftModuleName
+    self.javaPackage = javaPackage
+    self.swiftOutputDirectory = swiftOutputDirectory
+    self.javaOutputDirectory = javaOutputDirectory
+    self.symbolTable = translator.symbolTable
+    self.swiftStdlibTypes = translator.swiftStdlibTypes
+  }
+
+  func generate() throws {
+    try writeSwiftThunkSources()
+    print("[swift-java] Generated Swift sources (module: '\(self.swiftModuleName)') in: \(swiftOutputDirectory)/")
+
+    try writeExportedJavaSources()
+    print("[swift-java] Generated Java sources (package: '\(javaPackage)') in: \(javaOutputDirectory)/")
+  }
+}
+
+// ===== --------------------------------------------------------------------------------------------------------------
+// MARK: Defaults
+
+extension FFMSwift2JavaGenerator {
+
+  /// Default set Java imports for every generated file
+  static let defaultJavaImports: Array<String> = [
+    "org.swift.swiftkit.*",
+    "org.swift.swiftkit.SwiftKit",
+    "org.swift.swiftkit.util.*",
+
+    // Necessary for native calls and type mapping
+    "java.lang.foreign.*",
+    "java.lang.invoke.*",
+    "java.util.Arrays",
+    "java.util.stream.Collectors",
+    "java.util.concurrent.atomic.*",
+    "java.nio.charset.StandardCharsets",
+  ]
+}
+
 // ==== ---------------------------------------------------------------------------------------------------------------
 // MARK: File writing
 
-let PATH_SEPARATOR = "/"  // TODO: Windows
 
-extension Swift2JavaTranslator {
-
-  /// Every imported public type becomes a public class in its own file in Java.
-  public func writeExportedJavaSources(outputDirectory: String) throws {
+extension FFMSwift2JavaGenerator {
+  package func writeExportedJavaSources() throws {
     var printer = CodePrinter()
-    try writeExportedJavaSources(outputDirectory: outputDirectory, printer: &printer)
+    try writeExportedJavaSources(printer: &printer)
   }
 
-  public func writeExportedJavaSources(outputDirectory: String, printer: inout CodePrinter) throws {
-    for (_, ty) in importedTypes.sorted(by: { (lhs, rhs) in lhs.key < rhs.key }) {
+  /// Every imported public type becomes a public class in its own file in Java.
+  package func writeExportedJavaSources(printer: inout CodePrinter) throws {
+    for (_, ty) in analysis.importedTypes.sorted(by: { (lhs, rhs) in lhs.key < rhs.key }) {
       let filename = "\(ty.swiftNominal.name).java"
       log.info("Printing contents: \(filename)")
       printImportedNominal(&printer, ty)
 
       if let outputFile = try printer.writeContents(
-        outputDirectory: outputDirectory,
+        outputDirectory: javaOutputDirectory,
         javaPackagePath: javaPackagePath,
         filename: filename
       ) {
@@ -50,7 +113,7 @@ extension Swift2JavaTranslator {
       printModule(&printer)
 
       if let outputFile = try printer.writeContents(
-        outputDirectory: outputDirectory,
+        outputDirectory: javaOutputDirectory,
         javaPackagePath: javaPackagePath,
         filename: filename)
       {
@@ -63,26 +126,26 @@ extension Swift2JavaTranslator {
 // ==== ---------------------------------------------------------------------------------------------------------------
 // MARK: Java/text printing
 
-extension Swift2JavaTranslator {
+extension FFMSwift2JavaGenerator {
 
   /// Render the Java file contents for an imported Swift module.
   ///
   /// This includes any Swift global functions in that module, and some general type information and helpers.
-  public func printModule(_ printer: inout CodePrinter) {
+  func printModule(_ printer: inout CodePrinter) {
     printHeader(&printer)
     printPackage(&printer)
     printImports(&printer)
 
     printModuleClass(&printer) { printer in
       // TODO: print all "static" methods
-      for decl in importedGlobalFuncs {
+      for decl in analysis.importedGlobalFuncs {
         self.log.trace("Print imported decl: \(decl)")
         printFunctionDowncallMethods(&printer, decl)
       }
     }
   }
 
-  package func printImportedNominal(_ printer: inout CodePrinter, _ decl: ImportedNominalType) {
+  func printImportedNominal(_ printer: inout CodePrinter, _ decl: ImportedNominalType) {
     printHeader(&printer)
     printPackage(&printer)
     printImports(&printer)
@@ -143,7 +206,7 @@ extension Swift2JavaTranslator {
     }
   }
 
-  public func printHeader(_ printer: inout CodePrinter) {
+  func printHeader(_ printer: inout CodePrinter) {
     printer.print(
       """
       // Generated by jextract-swift
@@ -153,7 +216,7 @@ extension Swift2JavaTranslator {
     )
   }
 
-  public func printPackage(_ printer: inout CodePrinter) {
+  func printPackage(_ printer: inout CodePrinter) {
     printer.print(
       """
       package \(javaPackage);
@@ -162,14 +225,14 @@ extension Swift2JavaTranslator {
     )
   }
 
-  public func printImports(_ printer: inout CodePrinter) {
-    for i in Swift2JavaTranslator.defaultJavaImports {
+  func printImports(_ printer: inout CodePrinter) {
+    for i in FFMSwift2JavaGenerator.defaultJavaImports {
       printer.print("import \(i);")
     }
     printer.print("")
   }
 
-  package func printNominal(
+  func printNominal(
     _ printer: inout CodePrinter, _ decl: ImportedNominalType, body: (inout CodePrinter) -> Void
   ) {
     let parentProtocol: String
@@ -188,7 +251,7 @@ extension Swift2JavaTranslator {
     }
   }
 
-  public func printModuleClass(_ printer: inout CodePrinter, body: (inout CodePrinter) -> Void) {
+  func printModuleClass(_ printer: inout CodePrinter, body: (inout CodePrinter) -> Void) {
     printer.printBraceBlock("public final class \(swiftModuleName)") { printer in
       printPrivateConstructor(&printer, swiftModuleName)
 
@@ -261,7 +324,7 @@ extension Swift2JavaTranslator {
     }
   }
 
-  private func printClassConstants(printer: inout CodePrinter) {
+  func printClassConstants(printer: inout CodePrinter) {
     printer.print(
       """
       static final String LIB_NAME = "\(swiftModuleName)";
@@ -270,7 +333,7 @@ extension Swift2JavaTranslator {
     )
   }
 
-  private func printPrivateConstructor(_ printer: inout CodePrinter, _ typeName: String) {
+  func printPrivateConstructor(_ printer: inout CodePrinter, _ typeName: String) {
     printer.print(
       """
       private \(typeName)() {
@@ -296,7 +359,7 @@ extension Swift2JavaTranslator {
     )
   }
 
-  package func printToStringMethod(
+  func printToStringMethod(
     _ printer: inout CodePrinter, _ decl: ImportedNominalType
   ) {
     printer.print(
@@ -312,3 +375,4 @@ extension Swift2JavaTranslator {
       """)
   }
 }
+

Sources/JExtractSwiftLib/Swift2Java.swift

@@ -31,7 +31,6 @@ public struct SwiftToJava {
     }
 
     let translator = Swift2JavaTranslator(
-      javaPackage: config.javaPackage ?? "", // no package is ok, we'd generate all into top level
       swiftModuleName: swiftModule
     )
     translator.log.logLevel = config.logLevel ?? .info
@@ -89,11 +88,17 @@ public struct SwiftToJava {
 
     try translator.analyze()
 
-    try translator.writeSwiftThunkSources(outputDirectory: outputSwiftDirectory)
-    print("[swift-java] Generated Swift sources (module: '\(config.swiftModule ?? "")') in: \(outputSwiftDirectory)/")
+    switch config.mode {
+    case .some(.ffm), .none:
+      let generator = FFMSwift2JavaGenerator(
+        translator: translator,
+        javaPackage: config.javaPackage ?? "",
+        swiftOutputDirectory: outputSwiftDirectory,
+        javaOutputDirectory: outputJavaDirectory
+      )
 
-    try translator.writeExportedJavaSources(outputDirectory: outputJavaDirectory)
-    print("[swift-java] Generated Java sources (package: '\(config.javaPackage ?? "")') in: \(outputJavaDirectory)/")
+      try generator.generate()
+    }
 
     print("[swift-java] Imported Swift module '\(swiftModule)': " + "done.".green)
   }