Move ConstantFun to akka.util, #22813

akka-actor/src/main/scala/akka/util/ConstantFun.scala

@@ -0,0 +1,47 @@
+/**
+ * Copyright (C) 2015-2017 Lightbend Inc. <http://www.lightbend.com>
+ */
+package akka.util
+
+import akka.annotation.InternalApi
+import akka.japi.function.{ Function ⇒ JFun, Function2 ⇒ JFun2 }
+import akka.japi.{ Pair ⇒ JPair }
+
+/**
+ * INTERNAL API
+ */
+@InternalApi private[akka] object ConstantFun {
+  private[this] val JavaIdentityFunction = new JFun[Any, Any] {
+    @throws(classOf[Exception]) override def apply(param: Any): Any = param
+  }
+
+  val JavaPairFunction = new JFun2[AnyRef, AnyRef, AnyRef JPair AnyRef] {
+    def apply(p1: AnyRef, p2: AnyRef): AnyRef JPair AnyRef = JPair(p1, p2)
+  }
+
+  def javaCreatePairFunction[A, B]: JFun2[A, B, JPair[A, B]] = JavaPairFunction.asInstanceOf[JFun2[A, B, JPair[A, B]]]
+
+  def javaIdentityFunction[T]: JFun[T, T] = JavaIdentityFunction.asInstanceOf[JFun[T, T]]
+
+  def scalaIdentityFunction[T]: T ⇒ T = conforms.asInstanceOf[Function[T, T]]
+
+  def scalaAnyToNone[A, B]: A ⇒ Option[B] = none
+  def scalaAnyTwoToNone[A, B, C]: (A, B) ⇒ Option[C] = two2none
+  def javaAnyToNone[A, B]: A ⇒ Option[B] = none
+  def nullFun[T] = _nullFun.asInstanceOf[Any ⇒ T]
+
+  val zeroLong = (_: Any) ⇒ 0L
+
+  val oneLong = (_: Any) ⇒ 1L
+
+  val oneInt = (_: Any) ⇒ 1
+
+  private val _nullFun = (_: Any) ⇒ null
+
+  private val conforms = (a: Any) ⇒ a
+
+  private val none = (_: Any) ⇒ None
+
+  private val two2none = (_: Any, _: Any) ⇒ None
+
+}

akka-bench-jmh/src/main/scala/akka/stream/MaterializationBenchmark.scala

@@ -8,11 +8,11 @@ import java.util.concurrent.TimeUnit
 import akka.NotUsed
 import akka.actor.ActorSystem
 import akka.stream.scaladsl._
+import akka.util.ConstantFun
 import org.openjdk.jmh.annotations._
 import scala.concurrent.Await
 import scala.concurrent.duration._
 import scala.concurrent.Future
-import akka.stream.impl.ConstantFun
 import akka.Done
 
 object MaterializationBenchmark {

akka-stream-tests-tck/src/test/scala/akka/stream/tck/FlattenTest.scala

@@ -3,9 +3,9 @@
  */
 package akka.stream.tck
 
-import akka.stream.impl.ConstantFun
 import akka.stream.scaladsl.Sink
 import akka.stream.scaladsl.Source
+import akka.util.ConstantFun
 import org.reactivestreams.Publisher
 
 class FlattenTest extends AkkaPublisherVerification[Int] {

akka-stream-tests/src/test/java/akka/stream/javadsl/FlowTest.java

@@ -10,7 +10,7 @@ import akka.japi.JavaPartialFunction;
 import akka.japi.Pair;
 import akka.japi.function.*;
 import akka.stream.*;
-import akka.stream.impl.ConstantFun;
+import akka.util.ConstantFun;
 import akka.stream.javadsl.GraphDSL.Builder;
 import akka.stream.stage.*;
 import akka.testkit.AkkaSpec;

akka-stream-tests/src/test/java/akka/stream/javadsl/SourceTest.java

@@ -11,7 +11,7 @@ import akka.japi.Pair;
 import akka.japi.function.*;
 import akka.japi.pf.PFBuilder;
 import akka.stream.*;
-import akka.stream.impl.ConstantFun;
+import akka.util.ConstantFun;
 import akka.stream.stage.*;
 import akka.testkit.AkkaSpec;
 import akka.stream.testkit.TestPublisher;

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

@@ -4,12 +4,12 @@
 
 package akka.stream.impl.fusing
 
-import akka.stream.impl.ConstantFun
 import akka.stream.stage._
 import akka.stream.testkit.StreamSpec
 import akka.testkit.EventFilter
 import akka.stream._
 import akka.stream.impl.fusing.GraphStages.SimpleLinearGraphStage
+import akka.util.ConstantFun
 
 class InterpreterSpec extends StreamSpec with GraphInterpreterSpecKit {
   import Supervision.stoppingDecider

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

@@ -4,10 +4,10 @@
 
 package akka.stream.impl.fusing
 
-import akka.stream.impl.ConstantFun
 import akka.stream.Supervision
 import akka.stream.testkit.StreamSpec
 import akka.testkit.LongRunningTest
+import akka.util.ConstantFun
 
 class InterpreterStressSpec extends StreamSpec with GraphInterpreterSpecKit {
   import Supervision.stoppingDecider

akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowConcatAllSpec.scala

@@ -4,7 +4,7 @@
 package akka.stream.scaladsl
 
 import akka.NotUsed
-import akka.stream.impl.ConstantFun
+import akka.util.ConstantFun
 
 import scala.util.control.NoStackTrace
 import akka.stream.ActorMaterializer

akka-stream/src/main/scala/akka/stream/impl/ConstantFun.scala

@@ -10,6 +10,7 @@ import akka.japi.{ Pair ⇒ JPair }
 /**
  * INTERNAL API
  */
+@deprecated("Use akka.util.ConstantFun instead", "2.5.0")
 @InternalApi private[akka] object ConstantFun {
   private[this] val JavaIdentityFunction = new JFun[Any, Any] {
     @throws(classOf[Exception]) override def apply(param: Any): Any = param

akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala

@@ -3,10 +3,11 @@
  */
 package akka.stream.javadsl
 
+import akka.util.ConstantFun
 import akka.{ Done, NotUsed }
 import akka.event.LoggingAdapter
 import akka.japi.{ Pair, function }
-import akka.stream.impl.{ ConstantFun, StreamLayout }
+import akka.stream.impl.StreamLayout
 import akka.stream._
 import org.reactivestreams.Processor
 

akka-stream/src/main/scala/akka/stream/javadsl/Graph.scala

@@ -6,8 +6,8 @@ package akka.stream.javadsl
 import akka.NotUsed
 import akka.stream._
 import akka.japi.{ Pair, function }
+import akka.util.ConstantFun
 import scala.annotation.unchecked.uncheckedVariance
-import akka.stream.impl.ConstantFun
 
 /**
  * Merge several streams, taking elements as they arrive from input streams

akka-stream/src/main/scala/akka/stream/javadsl/Source.scala

@@ -6,12 +6,13 @@ package akka.stream.javadsl
 import java.util
 import java.util.Optional
 
+import akka.util.ConstantFun
 import akka.{ Done, NotUsed }
 import akka.actor.{ ActorRef, Cancellable, Props }
 import akka.event.LoggingAdapter
 import akka.japi.{ Pair, Util, function }
 import akka.stream._
-import akka.stream.impl.{ ConstantFun, LinearTraversalBuilder, SourceQueueAdapter, StreamLayout }
+import akka.stream.impl.{ LinearTraversalBuilder, SourceQueueAdapter, StreamLayout }
 import org.reactivestreams.{ Publisher, Subscriber }
 
 import scala.annotation.unchecked.uncheckedVariance

akka-stream/src/main/scala/akka/stream/javadsl/SubFlow.scala

@@ -7,7 +7,7 @@ import akka.NotUsed
 import akka.event.LoggingAdapter
 import akka.japi.function
 import akka.stream._
-import akka.stream.impl.ConstantFun
+import akka.util.ConstantFun
 
 import scala.collection.JavaConverters._
 import scala.annotation.unchecked.uncheckedVariance

akka-stream/src/main/scala/akka/stream/javadsl/SubSource.scala

@@ -7,7 +7,7 @@ import akka.NotUsed
 import akka.event.LoggingAdapter
 import akka.japi.function
 import akka.stream._
-import akka.stream.impl.ConstantFun
+import akka.util.ConstantFun
 
 import scala.collection.JavaConverters._
 import scala.annotation.unchecked.uncheckedVariance

akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala

@@ -9,6 +9,7 @@ import akka.Done
 import akka.stream.impl._
 import akka.stream.impl.fusing._
 import akka.stream.stage._
+import akka.util.ConstantFun
 import org.reactivestreams.{ Processor, Publisher, Subscriber, Subscription }
 
 import scala.annotation.unchecked.uncheckedVariance

akka-stream/src/main/scala/akka/stream/scaladsl/Graph.scala

@@ -10,6 +10,7 @@ import akka.stream.impl.fusing.GraphStages
 import akka.stream.impl.Stages.DefaultAttributes
 import akka.stream.scaladsl.Partition.PartitionOutOfBoundsException
 import akka.stream.stage.{ GraphStage, GraphStageLogic, InHandler, OutHandler }
+import akka.util.ConstantFun
 
 import scala.annotation.unchecked.uncheckedVariance
 import scala.annotation.tailrec

akka-stream/src/main/scala/akka/stream/scaladsl/Source.scala

@@ -4,6 +4,7 @@
 package akka.stream.scaladsl
 
 import akka.stream.impl.Stages.DefaultAttributes
+import akka.util.ConstantFun
 import akka.{ Done, NotUsed }
 import akka.actor.{ ActorRef, Cancellable, Props }
 import akka.stream.actor.ActorPublisher