[WIP] JExtractSwiftPlugin

.github/workflows/pull_request.yml

@@ -19,7 +19,8 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        swift_version: ['nightly-main']
+        # swift_version: ['nightly-main']
+        swift_version: ['6.0.2']
         os_version: ['jammy']
         jdk_vendor: ['Corretto']
     container:
@@ -43,8 +44,8 @@ jobs:
         if: steps.cache-jdk.outputs.cache-hit != 'true'
         run: "bash -xc 'JDK_VENDOR=${{ matrix.jdk_vendor }} ./docker/install_jdk.sh'"
         # TODO: not using setup-java since incompatible with the swiftlang/swift base image
-      - name: Install Untested Nightly Swift
-        run: "bash -xc './docker/install_untested_nightly_swift.sh'"
+        #      - name: Install Untested Nightly Swift
+        #        run: "bash -xc './docker/install_untested_nightly_swift.sh'"
       - name: Cache local Gradle repository
         uses: actions/cache@v4
         continue-on-error: true
@@ -79,7 +80,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        swift_version: ['nightly-main']
+        # swift_version: ['nightly-main']
+        swift_version: ['6.0.2']
         os_version: ['jammy']
         jdk_vendor: ['Corretto']
     container:
@@ -103,8 +105,8 @@ jobs:
         if: steps.cache-jdk.outputs.cache-hit != 'true'
         run: "bash -xc 'JDK_VENDOR=${{ matrix.jdk_vendor }} ./docker/install_jdk.sh'"
         # TODO: not using setup-java since incompatible with the swiftlang/swift base image
-      - name: Install Untested Nightly Swift
-        run: "bash -xc './docker/install_untested_nightly_swift.sh'"
+        #      - name: Install Untested Nightly Swift
+        #        run: "bash -xc './docker/install_untested_nightly_swift.sh'"
       - name: Cache local Gradle repository
         uses: actions/cache@v4
         continue-on-error: true

.licenseignore

@@ -37,3 +37,5 @@ Makefile
 gradle/wrapper/gradle-wrapper.properties
 gradlew
 gradlew.bat
+**/gradlew
+**/gradlew.bat

Package.swift

@@ -126,6 +126,14 @@ let package = Package(
       targets: ["JExtractSwift"]
     ),
 
+    // ==== Plugin for wrapping Java classes in Swift
+    .plugin(
+      name: "JExtractSwiftPlugin",
+      targets: [
+        "JExtractSwiftPlugin"
+      ]
+    ),
+
     // ==== Examples
 
     .library(
@@ -229,6 +237,7 @@ let package = Package(
         .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"])
       ]
     ),
+
     .plugin(
       name: "JavaCompilerPlugin",
       capability: .buildTool()
@@ -331,6 +340,14 @@ let package = Package(
       ]
     ),
 
+    .plugin(
+      name: "JExtractSwiftPlugin",
+      capability: .buildTool(),
+      dependencies: [
+        "JExtractSwiftTool"
+      ]
+    ),
+
     .testTarget(
       name: "JavaKitTests",
       dependencies: ["JavaKit", "JavaKitNetwork"],

Plugins/JExtractSwiftPlugin/Configuration.swift

@@ -0,0 +1,36 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import Foundation
+
+/// Configuration for the JExtractSwift translation tool, provided on a per-target
+/// basis.
+struct Configuration: Codable {
+  var javaPackage: String
+}
+
+func readConfiguration(sourceDir: String) throws -> Configuration {
+  let configFile = URL(filePath: sourceDir).appending(path: "JExtractSwift.config")
+  do {
+    let configData = try Data(contentsOf: configFile)
+    return try JSONDecoder().decode(Configuration.self, from: configData)
+  } catch {
+    throw ConfigurationError(message: "Failed to parse JExtractSwift configuration at '\(configFile)!'", error: error)
+  }
+}
+
+struct ConfigurationError: Error {
+  let message: String
+  let error: any Error
+}

Plugins/JExtractSwiftPlugin/JExtractSwiftPlugin.swift

@@ -0,0 +1,85 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import Foundation
+import PackagePlugin
+
+@main
+struct JExtractSwiftBuildToolPlugin: BuildToolPlugin {
+  func createBuildCommands(context: PluginContext, target: Target) throws -> [Command] {
+    guard let sourceModule = target.sourceModule else { return [] }
+
+    // Note: Target doesn't have a directoryURL counterpart to directory,
+    // so we cannot eliminate this deprecation warning.
+    let sourceDir = target.directory.string
+
+    let configuration = try readConfiguration(sourceDir: "\(sourceDir)")
+
+    // We use the the usual maven-style structure of "src/[generated|main|test]/java/..."
+    // that is common in JVM ecosystem
+    let outputDirectoryJava = context.pluginWorkDirectoryURL
+      .appending(path: "src")
+      .appending(path: "generated")
+      .appending(path: "java")
+    let outputDirectorySwift = context.pluginWorkDirectoryURL
+      .appending(path: "src")
+      .appending(path: "generated")
+      .appending(path: "Sources")
+
+    var arguments: [String] = [
+      "--swift-module", sourceModule.name,
+      "--package-name", configuration.javaPackage,
+      "--output-directory-java", outputDirectoryJava.path(percentEncoded: false),
+      "--output-directory-swift", outputDirectorySwift.path(percentEncoded: false),
+      // TODO: "--build-cache-directory", ...
+      //       Since plugins cannot depend on libraries we cannot detect what the output files will be,
+      //       as it depends on the contents of the input files. Therefore we have to implement this as a prebuild plugin.
+      //       We'll have to make up some caching inside the tool so we don't re-parse files which have not changed etc.
+    ]
+    arguments.append(sourceDir)
+
+    return [
+      .prebuildCommand(
+        displayName: "Generate Java wrappers for Swift types",
+        executable: try context.tool(named: "JExtractSwiftTool").url,
+        arguments: arguments,
+        // inputFiles: [ configFile ] + swiftFiles,
+        // outputFiles: outputJavaFiles
+        outputFilesDirectory: outputDirectorySwift
+      )
+    ]
+  }
+}
+
+// Note: the JAVA_HOME environment variable must be set to point to where
+// Java is installed, e.g.,
+//   Library/Java/JavaVirtualMachines/openjdk-21.jdk/Contents/Home.
+func findJavaHome() -> String {
+  if let home = ProcessInfo.processInfo.environment["JAVA_HOME"] {
+    return home
+  }
+
+  // This is a workaround for envs (some IDEs) which have trouble with
+  // picking up env variables during the build process
+  let path = "\(FileManager.default.homeDirectoryForCurrentUser.path()).java_home"
+  if let home = try? String(contentsOfFile: path, encoding: .utf8) {
+    if let lastChar = home.last, lastChar.isNewline {
+      return String(home.dropLast())
+    }
+
+    return home
+  }
+
+  fatalError("Please set the JAVA_HOME environment variable to point to where Java is installed.")
+}

Samples/JExtractPluginSampleApp/.gitignore

@@ -0,0 +1,8 @@
+.DS_Store
+/.build
+/Packages
+xcuserdata/
+DerivedData/
+.swiftpm/configuration/registries.json
+.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
+.netrc

Samples/JExtractPluginSampleApp/Package.swift

@@ -0,0 +1,70 @@
+// swift-tools-version: 6.0
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+import class Foundation.FileManager
+import class Foundation.ProcessInfo
+
+// Note: the JAVA_HOME environment variable must be set to point to where
+// Java is installed, e.g.,
+//   Library/Java/JavaVirtualMachines/openjdk-21.jdk/Contents/Home.
+func findJavaHome() -> String {
+  if let home = ProcessInfo.processInfo.environment["JAVA_HOME"] {
+    return home
+  }
+
+  // This is a workaround for envs (some IDEs) which have trouble with
+  // picking up env variables during the build process
+  let path = "\(FileManager.default.homeDirectoryForCurrentUser.path()).java_home"
+  if let home = try? String(contentsOfFile: path, encoding: .utf8) {
+    if let lastChar = home.last, lastChar.isNewline {
+      return String(home.dropLast())
+    }
+
+    return home
+  }
+
+  fatalError("Please set the JAVA_HOME environment variable to point to where Java is installed.")
+}
+let javaHome = findJavaHome()
+
+let javaIncludePath = "\(javaHome)/include"
+#if os(Linux)
+  let javaPlatformIncludePath = "\(javaIncludePath)/linux"
+#elseif os(macOS)
+  let javaPlatformIncludePath = "\(javaIncludePath)/darwin"
+#else
+  // TODO: Handle windows as well
+  #error("Currently only macOS and Linux platforms are supported, this may change in the future.")
+#endif
+
+let package = Package(
+    name: "JExtractPluginSampleApp",
+    platforms: [
+        .macOS(.v10_15),
+    ],
+   products: [
+     .library(
+       name: "JExtractPluginSampleLib",
+       type: .dynamic,
+       targets: ["JExtractPluginSampleLib"]
+     ),
+   ],
+   dependencies: [
+        .package(name: "swift-java", path: "../../"),
+    ],
+    targets: [
+        .target(
+            name: "JExtractPluginSampleLib",
+            dependencies: [
+            ],
+            swiftSettings: [
+              .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"])
+            ],
+            plugins: [
+              .plugin(name: "JExtractSwiftPlugin", package: "swift-java"),
+            ]
+        ),
+    ]
+)

Samples/JExtractPluginSampleApp/Sources/JExtractPluginSampleLib/JExtractSwift.config

@@ -0,0 +1,3 @@
+{
+  "javaPackage": "com.example.swift"
+}

Samples/JExtractPluginSampleApp/Sources/JExtractPluginSampleLib/MyCoolSwiftClass.swift

@@ -0,0 +1,26 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+public class MyCoolSwiftClass {
+  var number: Int
+  public init(number: Int) {
+    print("[swift] init(number: \(number))")
+    self.number = number
+  }
+
+  public func exposedToJava() {
+    print("[swift] exposedToJava()")
+    print("[swift]   number = \(number)")
+  }
+}