+str: Implement efficient stream op DSL

akka-stream-tests/src/test/scala/akka/stream/impl/fusing/InterpreterSpecKit.scala

@@ -0,0 +1,94 @@
+/**
+ * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.stream.impl.fusing
+
+import akka.stream.testkit.AkkaSpec
+
+trait InterpreterSpecKit extends AkkaSpec {
+
+  case object OnComplete
+  case object Cancel
+  case class OnError(cause: Throwable)
+  case class OnNext(elem: Any)
+  case object RequestOne
+
+  private[akka] case class Doubler[T]() extends DeterministicOp[T, T] {
+    var oneMore: Boolean = false
+    var lastElem: T = _
+
+    override def onPush(elem: T, ctxt: Context[T]): Directive = {
+      lastElem = elem
+      oneMore = true
+      ctxt.push(elem)
+    }
+
+    override def onPull(ctxt: Context[T]): Directive = {
+      if (oneMore) {
+        oneMore = false
+        ctxt.push(lastElem)
+      } else ctxt.pull()
+    }
+  }
+
+  abstract class TestSetup(ops: Seq[Op[_, _, _, _, _]], forkLimit: Int = 100, overflowToHeap: Boolean = false) {
+    private var lastEvent: Set[Any] = Set.empty
+
+    val upstream = new UpstreamProbe
+    val downstream = new DownstreamProbe
+    val interpreter = new OneBoundedInterpreter(upstream +: ops :+ downstream, forkLimit, overflowToHeap)
+    interpreter.init()
+
+    def lastEvents(): Set[Any] = {
+      val result = lastEvent
+      lastEvent = Set.empty
+      result
+    }
+
+    class UpstreamProbe extends BoundaryOp {
+
+      override def onDownstreamFinish(ctxt: BoundaryContext): Directive = {
+        lastEvent += Cancel
+        ctxt.exit()
+      }
+
+      override def onPull(ctxt: BoundaryContext): Directive = {
+        lastEvent += RequestOne
+        ctxt.exit()
+      }
+
+      override def onPush(elem: Any, ctxt: BoundaryContext): Directive =
+        throw new UnsupportedOperationException("Cannot push the boundary")
+
+      def onNext(elem: Any): Unit = enter().push(elem)
+      def onComplete(): Unit = enter().finish()
+      def onError(cause: Throwable): Unit = enter().fail(cause)
+
+    }
+
+    class DownstreamProbe extends BoundaryOp {
+      override def onPush(elem: Any, ctxt: BoundaryContext): Directive = {
+        lastEvent += OnNext(elem)
+        ctxt.exit()
+      }
+
+      override def onUpstreamFinish(ctxt: BoundaryContext): Directive = {
+        lastEvent += OnComplete
+        ctxt.exit()
+      }
+
+      override def onFailure(cause: Throwable, ctxt: BoundaryContext): Directive = {
+        lastEvent += OnError(cause)
+        ctxt.exit()
+      }
+
+      override def onPull(ctxt: BoundaryContext): Directive =
+        throw new UnsupportedOperationException("Cannot pull the boundary")
+
+      def requestOne(): Unit = enter().pull()
+
+      def cancel(): Unit = enter().finish()
+    }
+
+  }
+}