New wider interface of presentation compiler.

1 files changed, 68 insertions, 0 deletions

diff --git a/src/compiler/scala/tools/nsc/interactive/Response.scala b/src/compiler/scala/tools/nsc/interactive/Response.scala
new file mode 100644
index 0000000000..96e474a34a
--- /dev/null
+++ b/src/compiler/scala/tools/nsc/interactive/Response.scala
@@ -0,0 +1,68 @@
+package scala.tools.nsc
+package interactive
+
+import scala.concurrent.SyncVar
+
+/** Typical interaction, given a predicate <user-input>, a function <display>,
+ *  and an exception handler <handle>:
+ *
+ *  val TIMEOUT = 100 // (milliseconds) or something like that
+ *  val r = new Response()
+ *  while (!r.isComplete && !r.isCancelled) {
+ *    if (<user-input>) r.cancel()
+ *    else r.get(TIMEOUT) match {
+ *      case Some(Left(data)) => <display>(data)
+ *      case Some(Right(exc)) => <handle>(exc)
+ *      case None =>
+ *    }
+ *  }
+ */
+class Response[T] {
+
+  private val data = new SyncVar[Either[T, Throwable]]
+  private var complete = false
+  private var cancelled = false
+
+  /** Set provisional data, more to come
+   */
+  def setProvisionally(x: T) =
+    data.set(Left(x))
+
+  /** Set final data, and mark resposne as complete.
+   */
+  def set(x: T) = data.synchronized {
+    data.set(Left(x))
+    complete = true
+  }
+
+  def raise(exc: Throwable) = data.synchronized {
+    data.set(Right(exc))
+    complete = true
+  }
+
+  /** Get data, wait as long as necessary
+   */
+  def get: Either[T, Throwable] = data.get
+
+  /** Optionally get data within `timeout` milliseconds.
+   */
+  def get(timeout: Long): Option[Either[T, Throwable]] = data.get(timeout)
+
+  /** Final data set was stored
+   */
+  def isComplete = data.synchronized { complete }
+
+  /** Cancel action computing this response
+   */
+  def cancel() = data.synchronized { cancelled = true }
+
+  /** A cancel request for this response has been issued
+   */
+  def isCancelled = data.synchronized { cancelled }
+
+  def clear() = data.synchronized {
+    data.unset()
+    complete = false
+    cancelled = false
+  }
+}