chore: Add identity function.

apache · Jan 4, 2025 · 2332be6 · 2332be6
1 parent dad6b9f
commit 2332be6
Show file tree

Hide file tree

Showing 3 changed files with 15 additions and 8 deletions.
diff --git a/actor/src/main/scala/org/apache/pekko/japi/function/Function.scala b/actor/src/main/scala/org/apache/pekko/japi/function/Function.scala
@@ -13,6 +13,8 @@
 
 package org.apache.pekko.japi.function
 
+import org.apache.pekko.util.ConstantFun
+
 import scala.annotation.nowarn
 
 /**
@@ -28,6 +30,15 @@ trait Function[-T, +R] extends java.io.Serializable {
   def apply(param: T): R
 }
 
+object Function {
+
+  /**
+   * Returns a `Function` that always returns its input argument.
+   * @since 1.2.0
+   */
+  def identity[T]: Function[T, T] = ConstantFun.javaIdentityFunction
+}
+
 /**
  * A Function interface. Used to create 2-arg first-class-functions is Java.
  * `Serializable` is needed to be able to grab line number for Java 8 lambdas.

diff --git a/stream-tests/src/test/java/org/apache/pekko/stream/javadsl/FlowTest.java b/stream-tests/src/test/java/org/apache/pekko/stream/javadsl/FlowTest.java
@@ -749,9 +749,7 @@ public void mustBeAbleToUseConcatAllWithSources() throws Exception {
     mainInputs.add(Source.from(input2));
 
     final Flow<Source<Integer, NotUsed>, List<Integer>, NotUsed> flow =
-        Flow.<Source<Integer, NotUsed>>create()
-            .flatMapConcat(ConstantFun.javaIdentityFunction())
-            .grouped(6);
+        Flow.<Source<Integer, NotUsed>>create().flatMapConcat(Function.identity()).grouped(6);
     CompletionStage<List<Integer>> future =
         Source.from(mainInputs).via(flow).runWith(Sink.head(), system);
 
@@ -775,9 +773,7 @@ public void mustBeAbleToUseFlatMapMerge() throws Exception {
     mainInputs.add(Source.from(input4));
 
     final Flow<Source<Integer, NotUsed>, List<Integer>, NotUsed> flow =
-        Flow.<Source<Integer, NotUsed>>create()
-            .flatMapMerge(3, ConstantFun.javaIdentityFunction())
-            .grouped(60);
+        Flow.<Source<Integer, NotUsed>>create().flatMapMerge(3, Function.identity()).grouped(60);
     CompletionStage<List<Integer>> future =
         Source.from(mainInputs).via(flow).runWith(Sink.head(), system);
 

diff --git a/stream-tests/src/test/java/org/apache/pekko/stream/javadsl/SourceTest.java b/stream-tests/src/test/java/org/apache/pekko/stream/javadsl/SourceTest.java
@@ -470,7 +470,7 @@ public void mustBeAbleToUseConcatAllWithSources() throws Exception {
 
     CompletionStage<List<Integer>> future =
         Source.from(mainInputs)
-            .flatMapConcat(ConstantFun.javaIdentityFunction())
+            .flatMapConcat(Function.identity())
             .grouped(6)
             .runWith(Sink.head(), system);
 
@@ -495,7 +495,7 @@ public void mustBeAbleToUseFlatMapMerge() throws Exception {
 
     CompletionStage<List<Integer>> future =
         Source.from(mainInputs)
-            .flatMapMerge(3, ConstantFun.javaIdentityFunction())
+            .flatMapMerge(3, Function.identity())
             .grouped(60)
             .runWith(Sink.head(), system);