1 files changed, 49 insertions, 0 deletions
diff --git a/project/build/ForkSBT.scala b/project/build/ForkSBT.scala
new file mode 100644
index 0000000000..986c2166dc
--- /dev/null
+++ b/project/build/ForkSBT.scala
@@ -0,0 +1,49 @@
+/** Scala SBT build
+ *  Copyright 2005-2010 LAMP/EPFL
+ *  @author  Paul Phillips
+ */
+
+import sbt._
+
+/** Worked out a way to fork sbt tasks, preserving all sbt command line
+ *  options and without hardcoding anything.
+ */
+trait ForkSBT {
+  self: BasicLayer =>
+
+  def jvmArguments: List[String] = {
+    import scala.collection.jcl.Conversions._
+    import java.lang.management.ManagementFactory
+    ManagementFactory.getRuntimeMXBean().getInputArguments().toList
+  }
+
+  private var extraJVMArgs: List[String] = Nil
+  def withJVMArgs[T](args: String*)(body: => T): T = {
+    val saved = extraJVMArgs
+    extraJVMArgs = args.toList
+    try { body }
+    finally extraJVMArgs = saved
+  }
+
+  // Set a property in forked sbts to inhibit possible forking cycles.
+  def markForked = "-D" + forkProperty + "=true"
+
+  /** Forks a new process to run "sbt task task ...":
+   */
+  def forkTasks(tasks: String*): Boolean = {
+    require (!isForked, "Tried to fork but sbt is already forked: " + tasks.mkString(" "))
+
+    val sbtJar  = System.getProperty("java.class.path")
+    val sbtMain = "xsbt.boot.Boot"  // ok, much of anything.
+    val args   = jvmArguments ++ Seq(markForked, "-classpath", sbtJar, sbtMain) ++ tasks
+
+    log.info("Forking: " + args.mkString("java ", " ", ""))
+    Fork.java(None, args, StdoutOutput) == 0
+  }
+  def maybeFork(task: TaskManager#Task): Option[String] = maybeFork(task, "Error during external compilation.")
+  def maybeFork(task: TaskManager#Task, errorMsg: String): Option[String] = {
+    if (isForked) task.run
+    else if (forkTasks("project " + this.name, task.name)) None
+    else Some(errorMsg)
+  }
+}