BridgeJS: Generate ConvertibleToJSValue extensions for exported Swift classes

@js classes now automatically support conversion to JSValue, enabling seamless interoperability between Swift and JavaScript.

Author: kateinoigakukun

Benchmarks/Sources/Generated/JavaScript/BridgeJS.ExportSwift.json

@@ -19,5 +19,6 @@
         }
       }
     }
-  ]
+  ],
+  "moduleName" : "Benchmarks"
 }

Examples/PlayBridgeJS/Sources/PlayBridgeJS/Generated/BridgeJS.ExportSwift.swift

@@ -56,6 +56,14 @@ public func _bjs_PlayBridgeJS_deinit(pointer: UnsafeMutableRawPointer) {
     Unmanaged<PlayBridgeJS>.fromOpaque(pointer).release()
 }
 
+extension PlayBridgeJS: ConvertibleToJSValue {
+    var jsValue: JSValue {
+        @_extern(wasm, module: "PlayBridgeJS", name: "bjs_PlayBridgeJS_wrap")
+        func _bjs_PlayBridgeJS_wrap(_: UnsafeMutableRawPointer) -> Int32
+        return .object(JSObject(id: UInt32(bitPattern: _bjs_PlayBridgeJS_wrap(Unmanaged.passRetained(self).toOpaque()))))
+    }
+}
+
 @_expose(wasm, "bjs_PlayBridgeJSOutput_outputJs")
 @_cdecl("bjs_PlayBridgeJSOutput_outputJs")
 public func _bjs_PlayBridgeJSOutput_outputJs(_self: UnsafeMutableRawPointer) -> Void {
@@ -112,4 +120,12 @@ public func _bjs_PlayBridgeJSOutput_exportSwiftGlue(_self: UnsafeMutableRawPoint
 @_cdecl("bjs_PlayBridgeJSOutput_deinit")
 public func _bjs_PlayBridgeJSOutput_deinit(pointer: UnsafeMutableRawPointer) {
     Unmanaged<PlayBridgeJSOutput>.fromOpaque(pointer).release()
+}
+
+extension PlayBridgeJSOutput: ConvertibleToJSValue {
+    var jsValue: JSValue {
+        @_extern(wasm, module: "PlayBridgeJS", name: "bjs_PlayBridgeJSOutput_wrap")
+        func _bjs_PlayBridgeJSOutput_wrap(_: UnsafeMutableRawPointer) -> Int32
+        return .object(JSObject(id: UInt32(bitPattern: _bjs_PlayBridgeJSOutput_wrap(Unmanaged.passRetained(self).toOpaque()))))
+    }
 }

Examples/PlayBridgeJS/Sources/PlayBridgeJS/Generated/JavaScript/BridgeJS.ExportSwift.json

@@ -120,5 +120,6 @@
   ],
   "functions" : [
 
-  ]
+  ],
+  "moduleName" : "PlayBridgeJS"
 }

Plugins/BridgeJS/Sources/BridgeJSBuildPlugin/BridgeJSBuildPlugin.swift

@@ -42,6 +42,8 @@ struct BridgeJSBuildPlugin: BuildToolPlugin {
             executable: try context.tool(named: "BridgeJSTool").url,
             arguments: [
                 "export",
+                "--module-name",
+                target.name,
                 "--output-skeleton",
                 outputSkeletonPath.path,
                 "--output-swift",

Plugins/BridgeJS/Sources/BridgeJSCommandPlugin/BridgeJSCommandPlugin.swift

@@ -105,6 +105,8 @@ extension BridgeJSCommandPlugin.Context {
         try runBridgeJSTool(
             arguments: [
                 "export",
+                "--module-name",
+                target.name,
                 "--output-skeleton",
                 generatedJavaScriptDirectory.appending(path: "BridgeJS.ExportSwift.json").path,
                 "--output-swift",

Plugins/BridgeJS/Sources/BridgeJSCore/ExportSwift.swift

@@ -16,13 +16,15 @@ import BridgeJSSkeleton
 /// JavaScript glue code and TypeScript definitions.
 public class ExportSwift {
     let progress: ProgressReporting
+    let moduleName: String
 
     private var exportedFunctions: [ExportedFunction] = []
     private var exportedClasses: [ExportedClass] = []
     private var typeDeclResolver: TypeDeclResolver = TypeDeclResolver()
 
-    public init(progress: ProgressReporting) {
+    public init(progress: ProgressReporting, moduleName: String) {
         self.progress = progress
+        self.moduleName = moduleName
     }
 
     /// Processes a Swift source file to find declarations marked with @JS
@@ -53,7 +55,7 @@ public class ExportSwift {
         }
         return (
             outputSwift: outputSwift,
-            outputSkeleton: ExportedSkeleton(functions: exportedFunctions, classes: exportedClasses)
+            outputSkeleton: ExportedSkeleton(moduleName: moduleName, functions: exportedFunctions, classes: exportedClasses)
         )
     }
 
@@ -676,8 +678,41 @@ public class ExportSwift {
             )
         }
 
+        // Generate ConvertibleToJSValue extension
+        decls.append(renderConvertibleToJSValueExtension(klass: klass))
+
         return decls
     }
+
+    /// Generates a ConvertibleToJSValue extension for the exported class
+    ///
+    /// # Example
+    ///
+    /// For a class named `Greeter`, this generates:
+    ///
+    /// ```swift
+    /// extension Greeter: ConvertibleToJSValue {
+    ///     var jsValue: JSValue {
+    ///         @_extern(wasm, module: "MyModule", name: "bjs_Greeter_wrap")
+    ///         func _bjs_Greeter_wrap(_: UnsafeMutableRawPointer) -> Int32
+    ///         return JSObject(id: UInt32(bitPattern: _bjs_Greeter_wrap(Unmanaged.passRetained(self).toOpaque())))
+    ///     }
+    /// }
+    /// ```
+    func renderConvertibleToJSValueExtension(klass: ExportedClass) -> DeclSyntax {
+        let wrapFunctionName = "_bjs_\(klass.name)_wrap"
+        let externFunctionName = "bjs_\(klass.name)_wrap"
+
+        return """
+            extension \(raw: klass.name): ConvertibleToJSValue {
+                var jsValue: JSValue {
+                    @_extern(wasm, module: "\(raw: moduleName)", name: "\(raw: externFunctionName)")
+                    func \(raw: wrapFunctionName)(_: UnsafeMutableRawPointer) -> Int32
+                    return .object(JSObject(id: UInt32(bitPattern: \(raw: wrapFunctionName)(Unmanaged.passRetained(self).toOpaque()))))
+                }
+            }
+            """
+    }
 }
 
 extension AttributeListSyntax {

Plugins/BridgeJS/Sources/BridgeJSLink/BridgeJSLink.swift

@@ -203,6 +203,7 @@ struct BridgeJSLink {
                         bjs["swift_js_release"] = function(id) {
                             swift.memory.release(id);
                         }
+            \(renderSwiftClassWrappers().map { $0.indent(count: 12) }.joined(separator: "\n"))
             \(importObjectBuilders.flatMap { $0.importedLines }.map { $0.indent(count: 12) }.joined(separator: "\n"))
                     },
                     setInstance: (i) => {
@@ -249,6 +250,39 @@ struct BridgeJSLink {
         return (outputJs, outputDts)
     }
 
+    private func renderSwiftClassWrappers() -> [String] {
+        var wrapperLines: [String] = []
+        var modulesByName: [String: [ExportedClass]] = [:]
+        
+        // Group classes by their module name
+        for skeleton in exportedSkeletons {
+            if skeleton.classes.isEmpty { continue }
+            
+            if modulesByName[skeleton.moduleName] == nil {
+                modulesByName[skeleton.moduleName] = []
+            }
+            modulesByName[skeleton.moduleName]?.append(contentsOf: skeleton.classes)
+        }
+        
+        // Generate wrapper functions for each module
+        for (moduleName, classes) in modulesByName {
+            wrapperLines.append("// Wrapper functions for module: \(moduleName)")
+            wrapperLines.append("if (!importObject[\"\(moduleName)\"]) {")
+            wrapperLines.append("    importObject[\"\(moduleName)\"] = {};")
+            wrapperLines.append("}")
+            
+            for klass in classes {
+                let wrapperFunctionName = "bjs_\(klass.name)_wrap"
+                wrapperLines.append("importObject[\"\(moduleName)\"][\"\(wrapperFunctionName)\"] = function(pointer) {")
+                wrapperLines.append("    const obj = \(klass.name).__construct(pointer);")
+                wrapperLines.append("    return swift.memory.retain(obj);")
+                wrapperLines.append("};")
+            }
+        }
+        
+        return wrapperLines
+    }
+
     private func generateImportedTypeDefinitions() -> [String] {
         var typeDefinitions: [String] = []
 
@@ -736,7 +770,7 @@ struct BridgeJSLink {
 
         init(moduleName: String) {
             self.moduleName = moduleName
-            importedLines.append("const \(moduleName) = importObject[\"\(moduleName)\"] = {};")
+            importedLines.append("const \(moduleName) = importObject[\"\(moduleName)\"] = importObject[\"\(moduleName)\"] || {};")
         }
 
         func assignToImportObject(name: String, function: [String]) {

Plugins/BridgeJS/Sources/BridgeJSSkeleton/BridgeJSSkeleton.swift

@@ -93,10 +93,12 @@ public struct ExportedConstructor: Codable {
 }
 
 public struct ExportedSkeleton: Codable {
+    public let moduleName: String
     public let functions: [ExportedFunction]
     public let classes: [ExportedClass]
 
-    public init(functions: [ExportedFunction], classes: [ExportedClass]) {
+    public init(moduleName: String, functions: [ExportedFunction], classes: [ExportedClass]) {
+        self.moduleName = moduleName
         self.functions = functions
         self.classes = classes
     }

Plugins/BridgeJS/Sources/BridgeJSTool/BridgeJSTool.swift

@@ -149,6 +149,10 @@ import TS2Skeleton
             let parser = ArgumentParser(
                 singleDashOptions: [:],
                 doubleDashOptions: [
+                    "module-name": OptionRule(
+                        help: "The name of the module for external function references",
+                        required: true
+                    ),
                     "output-skeleton": OptionRule(
                         help: "The output file path for the skeleton of the exported Swift APIs",
                         required: true
@@ -168,7 +172,7 @@ import TS2Skeleton
                 arguments: Array(arguments.dropFirst())
             )
             let progress = ProgressReporting(verbose: doubleDashOptions["verbose"] == "true")
-            let exporter = ExportSwift(progress: progress)
+            let exporter = ExportSwift(progress: progress, moduleName: doubleDashOptions["module-name"]!)
             for inputFile in positionalArguments.sorted() {
                 let sourceURL = URL(fileURLWithPath: inputFile)
                 guard sourceURL.pathExtension == "swift" else { continue }

Plugins/BridgeJS/Tests/BridgeJSToolTests/BridgeJSLinkTests.swift

@@ -46,7 +46,7 @@ import Testing
     func snapshotExport(input: String) throws {
         let url = Self.inputsDirectory.appendingPathComponent(input)
         let sourceFile = Parser.parse(source: try String(contentsOf: url, encoding: .utf8))
-        let swiftAPI = ExportSwift(progress: .silent)
+        let swiftAPI = ExportSwift(progress: .silent, moduleName: "TestModule")
         try swiftAPI.addSourceFile(sourceFile, input)
         let name = url.deletingPathExtension().lastPathComponent