Some modifications to repl classloading to make...

Some modifications to repl classloading to make it usable in managed
classloader environments. Contributed by mark harrah. Review by rytz.

3 files changed, 39 insertions, 7 deletions

diff --git a/src/compiler/scala/tools/nsc/Interpreter.scala b/src/compiler/scala/tools/nsc/Interpreter.scala
index 7dd6d3ba04..3be1b44a4c 100644
--- a/src/compiler/scala/tools/nsc/Interpreter.scala
+++ b/src/compiler/scala/tools/nsc/Interpreter.scala
@@ -229,7 +229,9 @@ class Interpreter(val settings: Settings, out: PrintWriter) {
   private def methodByName(c: Class[_], name: String): reflect.Method =
     c.getMethod(name, classOf[Object])
 
-  protected def parentClassLoader: ClassLoader = this.getClass.getClassLoader()
+  protected def parentClassLoader: ClassLoader =
+    settings.explicitParentLoader.getOrElse( this.getClass.getClassLoader() )
+
   def getInterpreterClassLoader() = classLoader
 
   // Set the current Java "context" class loader to this interpreter's class loader
@@ -1267,15 +1269,16 @@ object Interpreter {
       }
     }
   }
-  def breakIf(assertion: => Boolean, args: DebugParam[_]*): Unit =
-    if (assertion) break(args.toList)
+  // provide the enclosing type T
+  //  in order to set up the interpreter's classpath and parent class loader properly
+  def breakIf[T: Manifest](assertion: => Boolean, args: DebugParam[_]*): Unit =
+    if (assertion) break[T](args.toList)
 
   // start a repl, binding supplied args
-  def break(args: List[DebugParam[_]]): Unit = {
+  def break[T: Manifest](args: List[DebugParam[_]]): Unit = {
     val intLoop = new InterpreterLoop
     intLoop.settings = new Settings(Console.println)
-    // XXX come back to the dot handling
-    intLoop.settings.classpath.value = "."
+    intLoop.settings.embeddedDefaults[T]
     intLoop.createInterpreter
     intLoop.in = InteractiveReader.createDefault(intLoop.interpreter)
 
diff --git a/src/compiler/scala/tools/nsc/InterpreterLoop.scala b/src/compiler/scala/tools/nsc/InterpreterLoop.scala
index f68ce4a5b4..bdcd7b9f58 100644
--- a/src/compiler/scala/tools/nsc/InterpreterLoop.scala
+++ b/src/compiler/scala/tools/nsc/InterpreterLoop.scala
@@ -117,7 +117,8 @@ class InterpreterLoop(in0: Option[BufferedReader], protected val out: PrintWrite
       settings.classpath append addedClasspath
 
     interpreter = new Interpreter(settings, out) {
-      override protected def parentClassLoader = classOf[InterpreterLoop].getClassLoader
+      override protected def parentClassLoader =
+        settings.explicitParentLoader.getOrElse( classOf[InterpreterLoop].getClassLoader )
     }
     interpreter.setContextClassLoader()
     // interpreter.quietBind("settings", "scala.tools.nsc.InterpreterSettings", interpreter.isettings)
diff --git a/src/compiler/scala/tools/nsc/settings/MutableSettings.scala b/src/compiler/scala/tools/nsc/settings/MutableSettings.scala
index 1e0e00e01d..c15a4279fb 100644
--- a/src/compiler/scala/tools/nsc/settings/MutableSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/MutableSettings.scala
@@ -11,6 +11,7 @@ package settings
 import io.{AbstractFile, VirtualDirectory}
 import scala.tools.util.StringOps
 import scala.collection.mutable.ListBuffer
+import scala.io.Source
 
 /** A mutable Settings object.
  */
@@ -160,6 +161,33 @@ class MutableSettings(val errorFn: String => Unit) extends AbsSettings with Scal
     doArgs(args)
   }
 
+  /** Initializes these settings for embedded use by type `T`.
+  * The class loader defining `T` should provide resources `app.class.path`
+  * and `boot.class.path`.  These resources should contain the application
+  * and boot classpaths in the same form as would be passed on the command line.*/
+  def embeddedDefaults[T: Manifest]: Unit =
+    embeddedDefaults(implicitly[Manifest[T]].erasure.getClassLoader)
+
+  /** Initializes these settings for embedded use by a class from the given class loader.
+  * The class loader for `T` should provide resources `app.class.path`
+  * and `boot.class.path`.  These resources should contain the application
+  * and boot classpaths in the same form as would be passed on the command line.*/
+  def embeddedDefaults(loader: ClassLoader) {
+    explicitParentLoader = Option(loader) // for the Interpreter parentClassLoader
+    getClasspath("app", loader) foreach { classpath.value = _ }
+    getClasspath("boot", loader) foreach { bootclasspath append _ }
+  }
+
+  /** The parent loader to use for the interpreter.*/
+  private[nsc] var explicitParentLoader: Option[ClassLoader] = None
+
+  /** Retrieves the contents of resource "${id}.class.path" from `loader`
+  * (wrapped in Some) or None if the resource does not exist.*/
+  private def getClasspath(id: String, loader: ClassLoader): Option[String] =
+    Option(loader).flatMap(ld => Option(ld.getResource(id + ".class.path"))).map { cp =>
+       Source.fromURL(cp).mkString
+    }
+
   // a wrapper for all Setting creators to keep our list up to date
   private def add[T <: Setting](s: T): T = {
     allSettings += s