PoC of using gradle to obtain classpath for dependency expressed in config

Benchmarks/Package.swift

@@ -0,0 +1,76 @@
+// swift-tools-version: 6.0
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import CompilerPluginSupport
+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: "swift-java-benchmarks",
+
+  platforms: [
+    .macOS(.v14)
+  ],
+
+  dependencies: [
+    .package(name: "swift-java", path: "../"),
+
+    // plugins
+    .package(url: "https://github.com/ordo-one/package-benchmark", .upToNextMajor(from: "1.4.0")),
+  ],
+
+  targets: [
+    .executableTarget(
+      name: "JavaApiCallBenchmarks",
+      dependencies: [
+        .product(name: "Benchmark", package: "package-benchmark"),
+        .product(name: "JavaRuntime", package: "swift-java"),
+        .product(name: "JavaKit", package: "swift-java"),
+        .product(name: "JavaKitNetwork", package: "swift-java"),
+      ],
+      path: "Benchmarks/JavaApiCallBenchmarks",
+      swiftSettings: [
+        .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"]),
+        .swiftLanguageMode(.v5),
+      ],
+      plugins: [
+        .plugin(name: "BenchmarkPlugin", package: "package-benchmark"),
+      ]
+    ),
+  ]
+)

JavaKit/build.gradle

@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+plugins {
+    id("build-logic.java-application-conventions")
+}
+
+group = "org.swift.javakit"
+version = "1.0-SNAPSHOT"
+
+repositories {
+    mavenCentral()
+}
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(22))
+    }
+}
+
+dependencies {
+    implementation("dev.gradleplugins:gradle-api:8.10.1")
+
+    testImplementation(platform("org.junit:junit-bom:5.10.0"))
+    testImplementation("org.junit.jupiter:junit-jupiter")
+}
+
+tasks.test {
+    useJUnitPlatform()
+    testLogging {
+        events("passed", "skipped", "failed")
+    }
+}

JavaKit/src/main/java/org/swift/javakit/dependencies/DependencyResolver.java

@@ -0,0 +1,75 @@
+package org.swift.javakit.dependencies;
+
+import org.gradle.tooling.GradleConnector;
+
+import java.io.*;
+import java.nio.file.Files;
+import java.util.Arrays;
+
+public class DependencyResolver {
+    /**
+     * May throw runtime exceptions including {@link org.gradle.api.internal.artifacts.ivyservice.TypedResolveException}
+     * if unable to resolve a dependency.
+     */
+    public static String getClasspathWithDependency(String[] dependencies) throws IOException {
+        File projectDir = Files.createTempDirectory("java-swift-dependencies").toFile();
+        projectDir.mkdirs();
+
+        File buildFile = new File(projectDir, "build.gradle");
+        try (PrintWriter writer = new PrintWriter(buildFile)) {
+            writer.println("plugins { id 'java-library' }");
+            writer.println("repositories { mavenCentral() }");
+
+            writer.println("dependencies {");
+            for (String dependency : dependencies) {
+                writer.println("implementation(\"" + dependency + "\")");
+            }
+            writer.println("}");
+
+            writer.println("""
+                    task printRuntimeClasspath {
+                        def runtimeClasspath = sourceSets.main.runtimeClasspath
+                        inputs.files(runtimeClasspath)
+                        doLast {
+                            println("CLASSPATH:${runtimeClasspath.asPath}")
+                        }
+                    }
+                    """);
+        }
+
+        File settingsFile = new File(projectDir, "settings.gradle.kts");
+        try (PrintWriter writer = new PrintWriter(settingsFile)) {
+            writer.println("""
+                    rootProject.name = "swift-java-resolve-dependencies-temp-project"
+                    """);
+        }
+
+        var connection = GradleConnector.newConnector()
+                .forProjectDirectory(projectDir)
+                .connect();
+
+        try (connection) {
+            ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+            PrintStream printStream = new PrintStream(outputStream);
+
+            connection.newBuild().forTasks(":printRuntimeClasspath")
+                    .setStandardError(new NoopOutputStream())
+                    .setStandardOutput(printStream)
+                    .run();
+
+            var all = outputStream.toString();
+            var classpath = Arrays.stream(all.split("\n"))
+                    .filter(s -> s.startsWith("CLASSPATH:"))
+                    .map(s -> s.substring("CLASSPATH:".length()))
+                    .findFirst().orElseThrow(() -> new RuntimeException("Could not find classpath output from ':printRuntimeClasspath' task."));
+            return classpath;
+        }
+    }
+
+    private static class NoopOutputStream extends OutputStream {
+        @Override
+        public void write(int b) throws IOException {
+            // ignore
+        }
+    }
+}

Package.swift

@@ -41,9 +41,9 @@ let javaIncludePath = "\(javaHome)/include"
 #endif
 
 let package = Package(
-  name: "JavaKit",
+  name: "swift-java",
   platforms: [
-    .macOS(.v10_15)
+    .macOS(.v13)
   ],
   products: [
     // ==== JavaKit (i.e. calling Java directly Swift utilities)
@@ -281,6 +281,22 @@ let package = Package(
       ]
     ),
 
+    .target(
+      name: "JavaKitDependencyResolver",
+      dependencies: [
+        "JavaKitReflection",
+      ],
+      exclude: [
+        "Java2Swift.config",
+        "org/javakit/deps/DependencyResolver.java",
+      ],
+      swiftSettings: [
+        .swiftLanguageMode(.v5),
+        .enableUpcomingFeature("BareSlashRegexLiterals"),
+        .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"]),
+      ]
+    ),
+
     .executableTarget(
       name: "Java2Swift",
       dependencies: [
@@ -292,6 +308,7 @@ let package = Package(
         "JavaKitJar",
         "JavaKitNetwork",
         "Java2SwiftLib",
+        "JavaKitDependencyResolver",
       ],
 
       swiftSettings: [

Plugins/Java2SwiftPlugin/Configuration.swift

@@ -25,4 +25,33 @@ struct Configuration: Codable {
   /// canonical Java class names (e.g., java.util.Vector) and the values are
   /// the corresponding Swift names (e.g., JavaVector).
   var classes: [String: String] = [:]
+
+  var dependencies: [JavaDependencyDescriptor] = []
 }
+
+struct JavaDependencyDescriptor: Codable {
+  var groupID: String
+  var artifactID: String
+  var version: String
+
+  init(from decoder: any Decoder) throws {
+    var container = try decoder.singleValueContainer()
+    let string = try container.decode(String.self)
+    let parts = string.split(separator: ":")
+    guard parts.count == 3 else {
+      throw JavaDependencyDescriptorError(message: "Illegal dependency, did not match: `groupID:artifactID:version")
+    }
+    self.groupID = String(parts[0])
+    self.artifactID = String(parts[1])
+    self.version = String(parts[2])
+  }
+
+  func encode(to encoder: any Encoder) throws {
+    var container = encoder.singleValueContainer()
+    try container.encode("\(self.groupID):\(self.artifactID):\(self.version)")
+  }
+
+  struct JavaDependencyDescriptorError: Error {
+    let message: String
+  }
+}

Plugins/JavaCompilerPlugin/JavaCompilerPlugin.swift

@@ -24,10 +24,12 @@ struct JavaCompilerBuildToolPlugin: BuildToolPlugin {
     let javaFiles = sourceModule.sourceFiles.map { $0.url }.filter {
       $0.pathExtension == "java"
     }
+    print("JAVA FILES IN \(sourceModule.sourceFiles) .... \(javaFiles)")
     if javaFiles.isEmpty {
       return []
     }
 
+
     // Note: Target doesn't have a directoryURL counterpart to directory,
     // so we cannot eliminate this deprecation warning.
     let sourceDir = target.directory.string

Samples/JavaDependenciesApp/.gitignore

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

Samples/JavaDependenciesApp/Package.swift

@@ -0,0 +1,63 @@
+// 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: "JavaDependenciesExample",
+    platforms: [
+        .macOS(.v10_15),
+    ],
+    dependencies: [
+        .package(name: "swift-java", path: "../../"),
+    ],
+    targets: [
+        .executableTarget(
+            name: "JavaJacksonDatabind",
+            dependencies: [
+            ],
+            swiftSettings: [
+              .unsafeFlags(["-I\(javaIncludePath)", "-I\(javaPlatformIncludePath)"])
+            ],
+            plugins: [
+              .plugin(name: "Java2SwiftPlugin", package: "swift-java"),
+            ]
+        ),
+    ]
+)

Samples/JavaDependenciesApp/Sources/JavaJacksonDatabind/Java2Swift.config

@@ -0,0 +1,6 @@
+{
+    "dependencies": [
+        "dev.gradleplugins:gradle-api:8.10.1"
+    ],
+    "classes": {}
+}

Samples/JavaDependenciesApp/Sources/JavaJacksonDatabind/main.swift

@@ -0,0 +1,25 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 JavaKit
+
+let jvm = try JavaVirtualMachine.shared(classPath: ["QuadraticSieve-1.0.jar"])
+do {
+  let sieveClass = try JavaClass<SieveOfEratosthenes>(environment: jvm.environment())
+  for prime in sieveClass.findPrimes(100)! {
+    print("Found prime: \(prime.intValue())")
+  }
+} catch {
+  print("Failure: \(error)")
+}