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Jun 5, 2025
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[JExtract] Static 'call' method in binding descriptor classes #246

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101 changes: 59 additions & 42 deletions Sources/JExtractSwift/Swift2JavaTranslator+JavaBindingsPrinting.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -24,18 +24,27 @@ extension Swift2JavaTranslator {
printJavaBindingDescriptorClass(&printer, decl)

// Render the "make the downcall" functions.
printFuncDowncallMethod(&printer, decl)
printJavaBindingWrapperMethod(&printer, decl)
}

/// Print FFM Java binding descriptors for the imported Swift API.
func printJavaBindingDescriptorClass(
package 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
printer.printBraceBlock(
"""
/**
* {@snippet lang=c :
* \(cFunc.description)
* }
*/
private static class \(cFunc.name)
"""
) { printer in
printFunctionDescriptorValue(&printer, cFunc)
printer.print(
"""
Expand All @@ -44,11 +53,12 @@ extension Swift2JavaTranslator {
public static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
"""
)
printJavaBindingDowncallMethod(&printer, cFunc)
}
}

/// Print the 'FunctionDescriptor' of the lowered cdecl thunk.
public func printFunctionDescriptorValue(
func printFunctionDescriptorValue(
_ printer: inout CodePrinter,
_ cFunc: CFunction
) {
Expand All @@ -74,9 +84,42 @@ extension Swift2JavaTranslator {
printer.print(");")
}

func printJavaBindingDowncallMethod(
_ printer: inout CodePrinter,
_ cFunc: CFunction
) {
let returnTy = cFunc.resultType.javaType
let maybeReturn = cFunc.resultType.isVoid ? "" : "return (\(returnTy)) "

var params: [String] = []
var args: [String] = []
for param in cFunc.parameters {
// ! unwrapping because cdecl lowering guarantees the parameter named.
params.append("\(param.type.javaType) \(param.name!)")
args.append(param.name!)
}
let paramsStr = params.joined(separator: ", ")
let argsStr = args.joined(separator: ", ")

printer.print(
"""
public static \(returnTy) call(\(paramsStr)) {
try {
if (SwiftKit.TRACE_DOWNCALLS) {
SwiftKit.traceDowncall(\(argsStr));
}
\(maybeReturn)HANDLE.invokeExact(\(argsStr));
} catch (Throwable ex$) {
throw new AssertionError("should not reach here", ex$);
}
}
"""
)
}

/// Print the calling body that forwards all the parameters to the `methodName`,
/// with adding `SwiftArena.ofAuto()` at the end.
public func printFuncDowncallMethod(
public func printJavaBindingWrapperMethod(
_ printer: inout CodePrinter,
_ decl: ImportedFunc) {
let methodName: String = switch decl.kind {
Expand Down Expand Up @@ -130,19 +173,11 @@ extension Swift2JavaTranslator {
_ printer: inout CodePrinter,
_ decl: ImportedFunc
) {
//=== Part 1: MethodHandle
let descriptorClassIdentifier = thunkNameRegistry.functionThunkName(decl: decl)
printer.print(
"var mh$ = \(descriptorClassIdentifier).HANDLE;"
)

let tryHead = if decl.translatedSignature.requiresTemporaryArena {
"try(var arena$ = Arena.ofConfined()) {"
} else {
"try {"
//=== Part 1: prepare temporary arena if needed.
if decl.translatedSignature.requiresTemporaryArena {
printer.print("try(var arena$ = Arena.ofConfined()) {")
printer.indent();
}
printer.print(tryHead);
printer.indent();

//=== Part 2: prepare all arguments.
var downCallArguments: [String] = []
Expand All @@ -151,15 +186,7 @@ extension Swift2JavaTranslator {
for (i, parameter) in decl.translatedSignature.parameters.enumerated() {
let original = decl.swiftSignature.parameters[i]
let parameterName = original.parameterName ?? "_\(i)"
let converted = parameter.conversion.render(&printer, parameterName)
let lowered: String
if parameter.conversion.isTrivial {
lowered = converted
} else {
// Store the conversion to a temporary variable.
lowered = "\(parameterName)$"
printer.print("var \(lowered) = \(converted);")
}
let lowered = parameter.conversion.render(&printer, parameterName)
downCallArguments.append(lowered)
}

Expand Down Expand Up @@ -191,14 +218,8 @@ extension Swift2JavaTranslator {
}

//=== Part 3: Downcall.
printer.print(
"""
if (SwiftKit.TRACE_DOWNCALLS) {
SwiftKit.traceDowncall(\(downCallArguments.joined(separator: ", ")));
}
"""
)
let downCall = "mh$.invokeExact(\(downCallArguments.joined(separator: ", ")))"
let thunkName = thunkNameRegistry.functionThunkName(decl: decl)
let downCall = "\(thunkName).call(\(downCallArguments.joined(separator: ", ")))"

//=== Part 4: Convert the return value.
if decl.translatedSignature.result.javaResultType == .void {
Expand All @@ -221,14 +242,10 @@ extension Swift2JavaTranslator {
}
}

printer.outdent()
printer.print(
"""
} catch (Throwable ex$) {
throw new AssertionError("should not reach here", ex$);
}
"""
)
if decl.translatedSignature.requiresTemporaryArena {
printer.outdent()
printer.print("}")
}
}

func renderMemoryLayoutValue(for javaType: JavaType) -> String {
Expand Down
2 changes: 1 addition & 1 deletion Sources/JExtractSwift/Swift2JavaTranslator+JavaTranslation.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -270,7 +270,7 @@ struct JavaTranslation {
return TranslatedResult(
javaResultType: javaType,
outParameters: [],
conversion: .cast(javaType)
conversion: .pass
)
}

Expand Down
11 changes: 2 additions & 9 deletions Tests/JExtractSwiftTests/FuncCallbackImportTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,7 @@ final class FuncCallbackImportTests {
let funcDecl = st.importedGlobalFuncs.first { $0.name == "callMe" }!

let output = CodePrinter.toString { printer in
st.printFuncDowncallMethod(&printer, funcDecl)
st.printJavaBindingWrapperMethod(&printer, funcDecl)
}

assertOutput(
Expand All @@ -59,15 +59,8 @@ final class FuncCallbackImportTests {
* }
*/
public static void callMe(java.lang.Runnable callback) {
var mh$ = swiftjava___FakeModule_callMe_callback.HANDLE;
try(var arena$ = Arena.ofConfined()) {
var callback$ = SwiftKit.toUpcallStub(callback, arena$);
if (SwiftKit.TRACE_DOWNCALLS) {
SwiftKit.traceDowncall(callback$);
}
mh$.invokeExact(callback$);
} catch (Throwable ex$) {
throw new AssertionError("should not reach here", ex$);
swiftjava___FakeModule_callMe_callback.call(SwiftKit.toUpcallStub(callback, arena$))
}
}
"""
Expand Down
146 changes: 121 additions & 25 deletions Tests/JExtractSwiftTests/FunctionDescriptorImportTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -51,9 +51,29 @@ final class FunctionDescriptorTests {
output,
expected:
"""
public static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
/* i: */SwiftValueLayout.SWIFT_INT
);
/**
* {@snippet lang=c :
* void swiftjava_SwiftModule_globalTakeInt_i(ptrdiff_t i)
* }
*/
private static class swiftjava_SwiftModule_globalTakeInt_i {
public static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
/* i: */SwiftValueLayout.SWIFT_INT
);
public static final MemorySegment ADDR =
SwiftModule.findOrThrow("swiftjava_SwiftModule_globalTakeInt_i");
public static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
public static void call(long i) {
try {
if (SwiftKit.TRACE_DOWNCALLS) {
SwiftKit.traceDowncall(i);
}
HANDLE.invokeExact(i);
} catch (Throwable ex$) {
throw new AssertionError("should not reach here", ex$);
}
}
}
"""
)
}
Expand All @@ -66,10 +86,30 @@ final class FunctionDescriptorTests {
output,
expected:
"""
public static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
/* l: */SwiftValueLayout.SWIFT_INT64,
/* i32: */SwiftValueLayout.SWIFT_INT32
);
/**
* {@snippet lang=c :
* void swiftjava_SwiftModule_globalTakeLongInt_l_i32(int64_t l, int32_t i32)
* }
*/
private static class swiftjava_SwiftModule_globalTakeLongInt_l_i32 {
public static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
/* l: */SwiftValueLayout.SWIFT_INT64,
/* i32: */SwiftValueLayout.SWIFT_INT32
);
public static final MemorySegment ADDR =
SwiftModule.findOrThrow("swiftjava_SwiftModule_globalTakeLongInt_l_i32");
public static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
public static void call(long l, int i32) {
try {
if (SwiftKit.TRACE_DOWNCALLS) {
SwiftKit.traceDowncall(l, i32);
}
HANDLE.invokeExact(l, i32);
} catch (Throwable ex$) {
throw new AssertionError("should not reach here", ex$);
}
}
}
"""
)
}
Expand All @@ -82,10 +122,30 @@ final class FunctionDescriptorTests {
output,
expected:
"""
public static final FunctionDescriptor DESC = FunctionDescriptor.of(
/* -> */SwiftValueLayout.SWIFT_INT,
/* i: */SwiftValueLayout.SWIFT_INT
);
/**
* {@snippet lang=c :
* ptrdiff_t swiftjava_SwiftModule_echoInt_i(ptrdiff_t i)
* }
*/
private static class swiftjava_SwiftModule_echoInt_i {
public static final FunctionDescriptor DESC = FunctionDescriptor.of(
/* -> */SwiftValueLayout.SWIFT_INT,
/* i: */SwiftValueLayout.SWIFT_INT
);
public static final MemorySegment ADDR =
SwiftModule.findOrThrow("swiftjava_SwiftModule_echoInt_i");
public static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
public static long call(long i) {
try {
if (SwiftKit.TRACE_DOWNCALLS) {
SwiftKit.traceDowncall(i);
}
return (long) HANDLE.invokeExact(i);
} catch (Throwable ex$) {
throw new AssertionError("should not reach here", ex$);
}
}
}
"""
)
}
Expand All @@ -98,10 +158,30 @@ final class FunctionDescriptorTests {
output,
expected:
"""
public static final FunctionDescriptor DESC = FunctionDescriptor.of(
/* -> */SwiftValueLayout.SWIFT_INT32,
/* self: */SwiftValueLayout.SWIFT_POINTER
);
/**
* {@snippet lang=c :
* int32_t swiftjava_SwiftModule_MySwiftClass_counter$get(const void *self)
* }
*/
private static class swiftjava_SwiftModule_MySwiftClass_counter$get {
public static final FunctionDescriptor DESC = FunctionDescriptor.of(
/* -> */SwiftValueLayout.SWIFT_INT32,
/* self: */SwiftValueLayout.SWIFT_POINTER
);
public static final MemorySegment ADDR =
SwiftModule.findOrThrow("swiftjava_SwiftModule_MySwiftClass_counter$get");
public static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
public static int call(java.lang.foreign.MemorySegment self) {
try {
if (SwiftKit.TRACE_DOWNCALLS) {
SwiftKit.traceDowncall(self);
}
return (int) HANDLE.invokeExact(self);
} catch (Throwable ex$) {
throw new AssertionError("should not reach here", ex$);
}
}
}
"""
)
}
Expand All @@ -113,10 +193,30 @@ final class FunctionDescriptorTests {
output,
expected:
"""
public static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
/* newValue: */SwiftValueLayout.SWIFT_INT32,
/* self: */SwiftValueLayout.SWIFT_POINTER
);
/**
* {@snippet lang=c :
* void swiftjava_SwiftModule_MySwiftClass_counter$set(int32_t newValue, const void *self)
* }
*/
private static class swiftjava_SwiftModule_MySwiftClass_counter$set {
public static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
/* newValue: */SwiftValueLayout.SWIFT_INT32,
/* self: */SwiftValueLayout.SWIFT_POINTER
);
public static final MemorySegment ADDR =
SwiftModule.findOrThrow("swiftjava_SwiftModule_MySwiftClass_counter$set");
public static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
public static void call(int newValue, java.lang.foreign.MemorySegment self) {
try {
if (SwiftKit.TRACE_DOWNCALLS) {
SwiftKit.traceDowncall(newValue, self);
}
HANDLE.invokeExact(newValue, self);
} catch (Throwable ex$) {
throw new AssertionError("should not reach here", ex$);
}
}
}
"""
)
}
Expand Down Expand Up @@ -145,10 +245,8 @@ 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, cFunc)
st.printJavaBindingDescriptorClass(&printer, funcDecl)
}

try body(output)
Expand Down Expand Up @@ -180,10 +278,8 @@ 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, cFunc)
st.printJavaBindingDescriptorClass(&printer, accessorDecl)
}

try body(getOutput)
Expand Down
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