jextract/jni: Make single-type mode available

Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+SwiftThunkPrinting.swift

@@ -71,6 +71,7 @@ extension FFMSwift2JavaGenerator {
     // === All types
     // We have to write all types to their corresponding output file that matches the file they were declared in,
     // because otherwise SwiftPM plugins will not pick up files apropriately -- we expect 1 output +SwiftJava.swift file for every input.
+
     let filteredTypes: [String: ImportedNominalType]
     if let singleType = config.singleType {
       filteredTypes = self.analysis.importedTypes.filter { $0.key == singleType }

Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaBindingsPrinting.swift

@@ -42,13 +42,21 @@ extension JNISwift2JavaGenerator {
   }
 
   package func writeExportedJavaSources(_ printer: inout CodePrinter) throws {
-    let importedTypes = analysis.importedTypes.sorted(by: { (lhs, rhs) in lhs.key < rhs.key })
+    let typesToExport: [(key: String, value: ImportedNominalType)]
+    if let singleType = config.singleType {
+      typesToExport = analysis.importedTypes
+        .filter { $0.key == singleType }
+        .sorted(by: { $0.key < $1.key })
+    } else {
+      typesToExport = analysis.importedTypes
+        .sorted(by: { $0.key < $1.key })
+    }
 
     var exportedFileNames: OrderedSet<String> = []
 
     // Each parent type goes into its own file
     // any nested types are printed inside the body as `static class`
-    for (_, ty) in importedTypes.filter({ _, type in type.parent == nil }) {
+    for (_, ty) in typesToExport.filter({ _, type in type.parent == nil }) {
       let filename = "\(ty.effectiveJavaSimpleName).java"
       logger.debug("Printing contents: \(filename)")
       printImportedNominal(&printer, ty)
@@ -63,17 +71,20 @@ extension JNISwift2JavaGenerator {
       }
     }
 
-    let filename = "\(self.swiftModuleName).java"
-    logger.trace("Printing module class: \(filename)")
-    printModule(&printer)
+    // Skip the module-level .swift file when generating for a single type
+    if config.singleType == nil {
+      let filename = "\(self.swiftModuleName).java"
+      logger.trace("Printing module class: \(filename)")
+      printModule(&printer)
 
-    if let outputFile = try printer.writeContents(
-      outputDirectory: javaOutputDirectory,
-      javaPackagePath: javaPackagePath,
-      filename: filename,
-    ) {
-      exportedFileNames.append(outputFile.path(percentEncoded: false))
-      logger.info("[swift-java] Generated: \(self.swiftModuleName).java (at \(outputFile))")
+      if let outputFile = try printer.writeContents(
+        outputDirectory: javaOutputDirectory,
+        javaPackagePath: javaPackagePath,
+        filename: filename,
+      ) {
+        exportedFileNames.append(outputFile.path(percentEncoded: false))
+        logger.info("[swift-java] Generated: \(self.swiftModuleName).java (at \(outputFile))")
+      }
     }
 
     // Write java sources list file

Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift

@@ -57,24 +57,35 @@ extension JNISwift2JavaGenerator {
     let moduleFilename = "\(moduleFilenameBase).swift"
 
     do {
-      logger.trace("Printing swift module class: \(moduleFilename)")
-
-      try printGlobalSwiftThunkSources(&printer)
-
-      if let outputFile = try printer.writeContents(
-        outputDirectory: self.swiftOutputDirectory,
-        javaPackagePath: nil,
-        filename: moduleFilename,
-      ) {
-        logger.info("Generated: \(moduleFilenameBase.bold).swift (at \(outputFile.absoluteString))")
-        self.expectedOutputSwiftFileNames.remove(moduleFilename)
+      // Skip the module-level .swift file when generating for a single type
+      if config.singleType == nil {
+        logger.trace("Printing swift module class: \(moduleFilename)")
+
+        try printGlobalSwiftThunkSources(&printer)
+
+        if let outputFile = try printer.writeContents(
+          outputDirectory: self.swiftOutputDirectory,
+          javaPackagePath: nil,
+          filename: moduleFilename,
+        ) {
+          logger.info("Generated: \(moduleFilenameBase.bold).swift (at \(outputFile.absoluteString))")
+          self.expectedOutputSwiftFileNames.remove(moduleFilename)
+        }
       }
 
       // === All types
       // We have to write all types to their corresponding output file that matches the file they were declared in,
       // because otherwise SwiftPM plugins will not pick up files apropriately -- we expect 1 output +SwiftJava.swift file for every input.
+
+      let filteredTypes: [String: ImportedNominalType]
+      if let singleType = config.singleType {
+        filteredTypes = self.analysis.importedTypes.filter { $0.key == singleType }
+      } else {
+        filteredTypes = self.analysis.importedTypes
+      }
+
       for group: (key: String, value: [Dictionary<String, ImportedNominalType>.Element]) in Dictionary(
-        grouping: self.analysis.importedTypes,
+        grouping: filteredTypes,
         by: { $0.value.sourceFilePath },
       ) {
         logger.warning("Writing types in file group: \(group.key): \(group.value.map(\.key))")