1 files changed, 39 insertions, 0 deletions
diff --git a/contrib/scoverage/src/ScoverageReportWorker.scala b/contrib/scoverage/src/ScoverageReportWorker.scala
new file mode 100644
index 00000000..1aaa31ad
--- /dev/null
+++ b/contrib/scoverage/src/ScoverageReportWorker.scala
@@ -0,0 +1,39 @@
+package mill.contrib.scoverage
+
+import mill.{Agg, T}
+import mill.api.{ClassLoader, Ctx, Result}
+import mill.define.{Discover, ExternalModule, Worker}
+import mill.eval.PathRef
+
+class ScoverageReportWorker {
+  private var scoverageInstanceCache = Option.empty[(Long, api.ScoverageReportWorkerApi)]
+
+  def bridge(classpath: Agg[os.Path])
+                    (implicit ctx: Ctx) = {
+    val classloaderSig =
+      classpath.map(p => p.toString().hashCode + os.mtime(p)).sum
+    scoverageInstanceCache match {
+      case Some((sig, bridge)) if sig == classloaderSig => bridge
+      case _ =>
+        val toolsClassPath = classpath.map(_.toIO.toURI.toURL).toVector
+        ctx.log.debug("Loading classes from\n"+toolsClassPath.mkString("\n"))
+        val cl = ClassLoader.create(
+          toolsClassPath,
+          getClass.getClassLoader
+        )
+        val bridge = cl
+          .loadClass("mill.contrib.scoverage.worker.ScoverageReportWorkerImpl")
+          .getDeclaredConstructor()
+          .newInstance()
+          .asInstanceOf[api.ScoverageReportWorkerApi]
+        scoverageInstanceCache = Some((classloaderSig, bridge))
+        bridge
+    }
+  }
+}
+
+object ScoverageReportWorkerApi extends ExternalModule {
+
+  def scoverageReportWorker = T.worker { new ScoverageReportWorker() }
+  lazy val millDiscover = Discover[this.type]
+}