jextract: Support Java Long & Double to Int func interface

Samples/SwiftAndJavaJarFFMSampleLib/Sources/MySwiftLibrary/MySwiftLibrary.swift

@@ -100,6 +100,14 @@ public func globalCallMeDoubleBinaryOperator(run: (Double, Double) -> Double) ->
   run(1.0, 2.0)
 }
 
+public func globalCallMeDoubleToIntFunction(run: (Double) -> Int32) -> Int32 {
+  run(1.0)
+}
+
+public func globalCallMeLongToIntFunction(run: (Int64) -> Int32) -> Int32 {
+  run(1)
+}
+
 // ==== Internal helpers
 
 func p(_ msg: String, file: String = #fileID, line: UInt = #line, function: String = #function) {

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

@@ -146,4 +146,16 @@ void call_globalCallMeDoubleBinaryOperator_noThrow() {
         double result = MySwiftLibrary.globalCallMeDoubleBinaryOperator((double a, double b) -> { return a + b; });
         assertEquals(3.0, result);
     }
+
+    @Test
+    void call_globalCallMeDoubleToIntFunction_noThrow() {
+        int result = MySwiftLibrary.globalCallMeDoubleToIntFunction((double a) -> { return (int) a; });
+        assertEquals(1, result);
+    }
+
+    @Test
+    void call_globalCallMeLongToIntFunction_noThrow() {
+        int result = MySwiftLibrary.globalCallMeLongToIntFunction((long a) -> { return (int) a; });
+        assertEquals(1, result);
+    }
 }

Samples/SwiftJavaExtractFFMSampleApp/Sources/MySwiftLibrary/MySwiftLibrary.swift

@@ -112,6 +112,14 @@ public func globalCallMeDoubleBinaryOperator(run: (Double, Double) -> Double) ->
   run(1.0, 2.0)
 }
 
+public func globalCallMeDoubleToIntFunction(run: (Double) -> Int32) -> Int32 {
+  run(1.0)
+}
+
+public func globalCallMeLongToIntFunction(run: (Int64) -> Int32) -> Int32 {
+  run(1)
+}
+
 public func globalReceiveRawBuffer(buf: UnsafeRawBufferPointer) -> Int {
   buf.count
 }

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

@@ -258,4 +258,16 @@ void call_globalCallMeDoubleBinaryOperator_noThrow() {
         double result = MySwiftLibrary.globalCallMeDoubleBinaryOperator((double a, double b) -> { return a + b; });
         assertEquals(3.0, result);
     }
+
+    @Test
+    void call_globalCallMeDoubleToIntFunction_noThrow() {
+        int result = MySwiftLibrary.globalCallMeDoubleToIntFunction((double a) -> { return (int) a; });
+        assertEquals(1, result);
+    }
+
+    @Test
+    void call_globalCallMeLongToIntFunction_noThrow() {
+        int result = MySwiftLibrary.globalCallMeLongToIntFunction((long a) -> { return (int) a; });
+        assertEquals(1, result);
+    }
 }

Samples/SwiftJavaExtractJNISampleApp/Sources/MySwiftLibrary/Closures.swift

@@ -85,6 +85,14 @@ public func globalCallMeDoubleBinaryOperator(run: (Double, Double) -> Double) ->
   run(1.0, 2.0)
 }
 
+public func globalCallMeDoubleToIntFunction(run: (Double) -> Int32) -> Int32 {
+  run(1.0)
+}
+
+public func globalCallMeLongToIntFunction(run: (Int64) -> Int32) -> Int32 {
+  run(1)
+}
+
 public func closureMultipleArguments(
   input1: Int64,
   input2: Int64,

Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/ClosuresTest.java

@@ -140,4 +140,16 @@ void globalCallMeDoubleBinaryOperator() {
         double result = MySwiftLibrary.globalCallMeDoubleBinaryOperator((double a, double b) -> { return a + b; });
         assertEquals(3.0, result);
     }
+
+    @Test
+    void globalCallMeDoubleToIntFunction() {
+        int result = MySwiftLibrary.globalCallMeDoubleToIntFunction((double a) -> { return (int) a; });
+        assertEquals(1, result);
+    }
+
+    @Test
+    void globalCallMeLongToIntFunction() {
+        int result = MySwiftLibrary.globalCallMeLongToIntFunction((long a) -> { return (int) a; });
+        assertEquals(1, result);
+    }
 }

Sources/ExampleSwiftLibrary/MySwiftLibrary.swift

@@ -107,6 +107,14 @@ public func globalCallMeDoubleBinaryOperator(run: (Double, Double) -> Double) ->
   run(1.0, 2.0)
 }
 
+public func globalCallMeDoubleToIntFunction(run: (Double) -> Int32) -> Int32 {
+  run(1.0)
+}
+
+public func globalCallMeLongToIntFunction(run: (Int64) -> Int32) -> Int32 {
+  run(1)
+}
+
 public func globalReceiveRawBuffer(buf: UnsafeRawBufferPointer) -> Int {
   buf.count
 }

Sources/JExtractSwiftLib/JavaTypes/JavaType+JDK.swift

@@ -110,6 +110,16 @@ extension JavaType {
     .class(package: "java.util.function", name: "DoubleBinaryOperator")
   }
 
+  /// The description of the type java.util.function.DoubleToIntFunction.
+  static var javaUtilFunctionDoubleToIntFunction: JavaType {
+    .class(package: "java.util.function", name: "DoubleToIntFunction")
+  }
+
+  /// The description of the type java.util.function.LongToIntFunction.
+  static var javaUtilFunctionLongToIntFunction: JavaType {
+    .class(package: "java.util.function", name: "LongToIntFunction")
+  }
+
   /// The description of the type java.lang.Class.
   static var javaLangClass: JavaType {
     .class(package: "java.lang", name: "Class")

Sources/JExtractSwiftLib/KnownFunctionalInterfaces.swift

@@ -141,6 +141,20 @@ struct KnownJavaFunctionalInterface: Sendable {
     result: .double
   )
 
+  static let doubleToIntFunction = KnownJavaFunctionalInterface(
+    JavaType.javaUtilFunctionDoubleToIntFunction,
+    method: "applyAsInt",
+    parameters: [.double],
+    result: .int
+  )
+
+  static let longToIntFunction = KnownJavaFunctionalInterface(
+    JavaType.javaUtilFunctionLongToIntFunction,
+    method: "applyAsInt",
+    parameters: [.long],
+    result: .int
+  )
+
   static let all: [KnownJavaFunctionalInterface] = [
     .runnable,
     .booleanSupplier,
@@ -159,6 +173,8 @@ struct KnownJavaFunctionalInterface: Sendable {
     .intBinaryOperator,
     .longBinaryOperator,
     .doubleBinaryOperator,
+    .doubleToIntFunction,
+    .longToIntFunction,
   ]
 
   static func find(parameters: [JavaType], result: JavaType) -> KnownJavaFunctionalInterface? {
@@ -248,6 +264,19 @@ struct KnownJavaFunctionalInterface: Sendable {
       }
     }
 
+    // To int functions
+    if parameters.count == 1 && result.isInt32 {
+      let parameter = parameters[0].type
+      return switch () {
+      case _ where parameter.isInt64:
+        longToIntFunction
+      case _ where parameter.isDouble:
+        doubleToIntFunction
+      default:
+        nil
+      }
+    }
+
     // Binary operators
     if parameters.count == 2 && parameters[0].type == result && parameters[1].type == result {
       let parameter = parameters[0].type

Tests/JExtractSwiftTests/FuncCallbackImportTests.swift

@@ -47,6 +47,9 @@ final class FuncCallbackImportTests {
     public func callMeLongPredicate(callback: (Int64) -> Bool)
     public func callMeDoublePredicate(callback: (Double) -> Bool)
 
+    public func callMeDoubleToIntFunction(callback: (Double) -> Int32)
+    public func callMeLongToIntFunction(callback: (Int64) -> Int32)
+
     public func callMeIntUnaryOperator(callback: (Int32) -> Int32)
     public func callMeLongUnaryOperator(callback: (Int64) -> Int64)
     public func callMeDoubleUnaryOperator(callback: (Double) -> Double)
@@ -854,6 +857,92 @@ final class FuncCallbackImportTests {
     )
   }
 
+  @Test("Import: public func callMeDoubleToIntFunction(callback: (Double) -> Int32)")
+  func func_callMecallMeDoubleToIntFunctionFunc_callback() throws {
+    var config = Configuration()
+    config.swiftModule = "__FakeModule"
+    let st = makeSwiftJavaAnalyzer(config: config)
+    st.log.logLevel = .error
+
+    try st.analyze(path: "Fake.swift", text: Self.class_interfaceFile)
+
+    let funcDecl = st.extractedGlobalFuncs.first { $0.name == "callMeDoubleToIntFunction" }!
+
+    let generator = FFMSwift2JavaGenerator(
+      config: config,
+      translator: st,
+      javaPackage: "com.example.swift",
+      swiftOutputDirectory: "/fake",
+      javaOutputDirectory: "/fake"
+    )
+
+    let output = JavaPrinter.toString { printer in
+      generator.printFunctionDowncallMethods(&printer, funcDecl)
+    }
+
+    assertOutput(
+      output,
+      expectedChunks: [
+        """
+        /**
+         * Downcall to Swift:
+         * {@snippet lang=swift :
+         * public func callMeDoubleToIntFunction(callback: (Double) -> Int32)
+         * }
+         */
+        public static void callMeDoubleToIntFunction(java.util.function.DoubleToIntFunction callback) {
+          try(var arena$ = Arena.ofConfined()) {
+            swiftjava___FakeModule_callMeDoubleToIntFunction_callback.call(callMeDoubleToIntFunction.$toUpcallStub(callback, arena$));
+          }
+        }
+        """
+      ]
+    )
+  }
+
+  @Test("Import: public func callMeLongToIntFunction(callback: (Int64) -> Int32)")
+  func func_callMecallMeLongToIntFunctionFunc_callback() throws {
+    var config = Configuration()
+    config.swiftModule = "__FakeModule"
+    let st = makeSwiftJavaAnalyzer(config: config)
+    st.log.logLevel = .error
+
+    try st.analyze(path: "Fake.swift", text: Self.class_interfaceFile)
+
+    let funcDecl = st.extractedGlobalFuncs.first { $0.name == "callMeLongToIntFunction" }!
+
+    let generator = FFMSwift2JavaGenerator(
+      config: config,
+      translator: st,
+      javaPackage: "com.example.swift",
+      swiftOutputDirectory: "/fake",
+      javaOutputDirectory: "/fake"
+    )
+
+    let output = JavaPrinter.toString { printer in
+      generator.printFunctionDowncallMethods(&printer, funcDecl)
+    }
+
+    assertOutput(
+      output,
+      expectedChunks: [
+        """
+        /**
+         * Downcall to Swift:
+         * {@snippet lang=swift :
+         * public func callMeLongToIntFunction(callback: (Int64) -> Int32)
+         * }
+         */
+        public static void callMeLongToIntFunction(java.util.function.LongToIntFunction callback) {
+          try(var arena$ = Arena.ofConfined()) {
+            swiftjava___FakeModule_callMeLongToIntFunction_callback.call(callMeLongToIntFunction.$toUpcallStub(callback, arena$));
+          }
+        }
+        """
+      ]
+    )
+  }
+
   @Test("Import: public func callMecallMeIntBinaryOperatorFunc(callback: (Int32, Int32) -> Int32)")
   func func_callMecallMeIntBinaryOperatorFunc_callback() throws {
     var config = Configuration()