WIP

Author: rintaro

Sources/JExtractSwift/ImportedDecls.swift

@@ -42,7 +42,7 @@ public final class ImportedFunc: ImportedDecl, CustomStringConvertible {
   public var module: String
 
   /// The function name.
-  /// e.g., "init" for an initializer or "f" for "f(a:b:)".
+  /// e.g., "init" for an initializer or "foo" for "foo(a:b:)".
   public var name: String
 
   public var swiftDecl: any DeclSyntaxProtocol
@@ -61,6 +61,11 @@ public final class ImportedFunc: ImportedDecl, CustomStringConvertible {
     loweredSignature.original
   }
 
+  package func cFunctionDecl(cName: String) -> CFunction {
+    // 'try!' because we know 'loweredSignature' can be described with C.
+    try! loweredSignature.cFunctionDecl(cName: cName)
+  }
+
   package var kind: SwiftAPIKind {
     loweredSignature.apiKind
   }

Sources/JExtractSwift/Swift2JavaTranslator+JavaBindingsPrinting.swift

@@ -310,12 +310,7 @@ extension Swift2JavaTranslator {
   ) {
     printer.printSeparator(decl.displayName)
 
-    let descClassIdentifier = thunkNameRegistry.functionThunkName(decl: decl)
-    printer.printBraceBlock("private static class \(descClassIdentifier)") { printer in
-      printFunctionDescriptorValue(&printer, decl)
-      printFunctionAddrValue(&printer, decl)
-      printFunctionHandleValue(&printer)
-    }
+    printJavaBindingDescriptorClass(&printer, decl)
 
     // Render the "make the downcall" functions.
     printInitializerDowncallConstructor(&printer, decl)
@@ -327,71 +322,59 @@ extension Swift2JavaTranslator {
   ) {
     printer.printSeparator(decl.displayName)
 
-    let descClassIdentifier = thunkNameRegistry.functionThunkName(decl: decl)
-    printer.printBraceBlock("private static class \(descClassIdentifier)") { printer in
-      printFunctionDescriptorValue(&printer, decl)
-      printFunctionAddrValue(&printer, decl)
-      printFunctionHandleValue(&printer)
-    }
+    printJavaBindingDescriptorClass(&printer, decl)
 
     // Render the "make the downcall" functions.
     printFuncDowncallMethod(&printer, decl)
   }
 
-  /// Print the 'FunctionDescriptor' of the Swift API.
-  public func printFunctionDescriptorValue(
+  /// Printer FFM Java binding descriptors for the imported Swift API.
+  func printJavaBindingDescriptorClass(
     _ printer: inout CodePrinter,
     _ decl: ImportedFunc
+  ) {
+    let thunkName = thunkNameRegistry.functionThunkName(decl: decl)
+    let cFunc = decl.cFunctionDecl(cName: thunkName)
+
+    printer.printBraceBlock("private static class \(cFunc.name)") { printer in
+      printFunctionDescriptorValue(&printer, cFunc)
+      printer.print(
+        """
+        public static final MemorySegment ADDR =
+          \(self.swiftModuleName).findOrThrow("\(cFunc.name)");
+        public static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
+        """
+      )
+    }
+  }
+
+  /// Print the 'FunctionDescriptor' of the lowered cdecl thunk.
+  public func printFunctionDescriptorValue(
+    _ printer: inout CodePrinter,
+    _ cFunc: CFunction
   ) {
     printer.start("public static final FunctionDescriptor DESC = ")
 
-    let loweredSignature = decl.loweredSignature
-    let loweredParams = loweredSignature.allLoweredParameters
-    let resultType = try! CType(cdeclType: loweredSignature.result.cdeclResultType)
-    let isEmptyParam = loweredParams.isEmpty
-    if resultType.isVoid {
+    let isEmptyParam = cFunc.parameters.isEmpty
+    if cFunc.resultType.isVoid {
       printer.print("FunctionDescriptor.ofVoid(", isEmptyParam ? .continue : .newLine)
       printer.indent()
     } else {
       printer.print("FunctionDescriptor.of(")
       printer.indent()
       printer.print("/* -> */", .continue)
-      printer.print(resultType.foreignValueLayout, .parameterNewlineSeparator(isEmptyParam))
+      printer.print(cFunc.resultType.foreignValueLayout, .parameterNewlineSeparator(isEmptyParam))
     }
 
-    for (param, isLast) in loweredParams.withIsLast {
-      let paramType = try! CType(cdeclType: param.type)
-      printer.print("/* \(param.parameterName ?? "_"): */", .continue)
-      printer.print(paramType.foreignValueLayout, .parameterNewlineSeparator(isLast))
+    for (param, isLast) in cFunc.parameters.withIsLast {
+      printer.print("/* \(param.name ?? "_"): */", .continue)
+      printer.print(param.type.foreignValueLayout, .parameterNewlineSeparator(isLast))
     }
 
     printer.outdent()
     printer.print(");")
   }
 
-  func printFunctionAddrValue(
-    _ printer: inout CodePrinter,
-    _ decl: ImportedFunc
-  ) {
-    let thunkName = thunkNameRegistry.functionThunkName(decl: decl)
-    printer.print(
-      """
-      public static final MemorySegment ADDR =
-        \(self.swiftModuleName).findOrThrow("\(thunkName)");
-      """
-    )
-  }
-
-  func printFunctionHandleValue(
-    _ printer: inout CodePrinter
-  ) {
-    printer.print(
-      """
-      public static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
-      """
-    )
-  }
-
   public func printInitializerDowncallConstructor(
     _ printer: inout CodePrinter,
     _ decl: ImportedFunc
@@ -562,10 +545,10 @@ extension Swift2JavaTranslator {
     } else if decl.translatedSignature.result.javaResultType == .void {
       printer.print("\(downCall);")
     } else {
-      let placeholder = if !decl.translatedSignature.result.outParameters.isEmpty {
-        "_result"
-      } else {
+      let placeholder = if decl.translatedSignature.result.outParameters.isEmpty {
         downCall
+      } else {
+        "_result"
       }
       let result = decl.translatedSignature.result.conversion.render(&printer, placeholder)
 

Sources/JExtractSwift/Swift2JavaTranslator.swift

@@ -54,7 +54,7 @@ public final class Swift2JavaTranslator {
 
   package let symbolTable: SwiftSymbolTable
 
-  var thunkNameRegistry: ThunkNameRegistry = ThunkNameRegistry()
+  package var thunkNameRegistry: ThunkNameRegistry = ThunkNameRegistry()
 
   /// The name of the Swift module being translated.
   var swiftModuleName: String {

Tests/JExtractSwiftTests/FunctionDescriptorImportTests.swift

@@ -145,8 +145,10 @@ extension FunctionDescriptorTests {
       $0.name == methodIdentifier
     }!
 
+    let thunkName = st.thunkNameRegistry.functionThunkName(decl: funcDecl)
+    let cFunc = funcDecl.cFunctionDecl(cName: thunkName)
     let output = CodePrinter.toString { printer in
-      st.printFunctionDescriptorValue(&printer, funcDecl)
+      st.printFunctionDescriptorValue(&printer, cFunc)
     }
 
     try body(output)
@@ -178,9 +180,10 @@ extension FunctionDescriptorTests {
       fatalError("Cannot find descriptor of: \(identifier)")
     }
 
+    let thunkName = st.thunkNameRegistry.functionThunkName(decl: accessorDecl)
+    let cFunc = accessorDecl.cFunctionDecl(cName: thunkName)
     let getOutput = CodePrinter.toString { printer in
-      st.printFunctionDescriptorValue(
-        &printer, accessorDecl)
+      st.printFunctionDescriptorValue(&printer, cFunc)
     }
 
     try body(getOutput)