Merge pull request ReactiveX#420 from samuelgruetter/scalaadaptor

Scala Adaptor

Author: benjchristensen

language-adaptors/rxjava-scala-java/README.md

@@ -62,7 +62,14 @@ For more examples, see [RxScalaDemo.scala](https://github.com/Netflix/RxJava/blo
 
 Scala code using Rx should only import members from `rx.lang.scala` and below.
 
-Work on this adaptor is still in progress, and for the moment, the best source of documentation are the comments in the source code of [`rx.lang.scala.Observable`](https://github.com/Netflix/RxJava/blob/master/language-adaptors/rxjava-scala/src/main/scala/rx/lang/scala/Observable.scala).
+
+## Documentation
+
+The API documentation can be found [here](http://rxscala.github.io/scaladoc/index.html#rx.lang.scala.Observable).
+
+You can build the API documentation yourself by running `./gradlew scaladoc` in the RxJava root directory.
+
+Then navigate to `RxJava/language-adaptors/rxjava-scala/build/docs/scaladoc/index.html` to display it.
 
 
 ## Binaries

language-adaptors/rxjava-scala-java/build.gradle

@@ -4,14 +4,19 @@ TODOs for Scala Adapter
 
 This is a (probably incomplete) list of what still needs to be done in the Scala adaptor:
 
-*    mirror complete Java package structure in Scala
-*    objects for classes with static methods or singletons (e.g. Schedulers, Subscriptions)
-*    Notification as a case class
-*    integrating Scala Futures, should there be a common base interface for Futures and Observables?
-*    Add methods present in Scala collections library, but not in RxJava, e.g. aggregate à la Scala, collect, exists, tails, ...
+*    Integrating Scala Futures: Should there be a common base interface for Futures and Observables? And if all subscribers of an Observable wrapping a Future unsubscribe, the Future should be cancelled, but Futures do not support cancellation.
+*    Add methods present in Scala collections library, but not in RxJava, e.g. aggregate à la Scala, collect, tails, ...
 *    combineLatest with arities > 2
-*    decide where the MovieLib/MovieLibUsage (use Scala code from Java code) example should live and make sure gradle builds it in the right order
+*    Implicit schedulers?
 *    Avoid text duplication in scaladoc using templates, add examples, distinction between use case signature and full signature
 *    other small TODOs
 
 
+(Implicit) schedulers for interval: Options:
+
+```scala
+def interval(duration: Duration)(implicit scheduler: Scheduler): Observable[Long]
+def interval(duration: Duration)(scheduler: Scheduler): Observable[Long]
+def interval(scheduler: Scheduler)(duration: Duration): Observable[Long]
+def interval(duration: Duration, scheduler: Scheduler): Observable[Long] && def interval(duration: Duration): Observable[Long] 
+````

language-adaptors/rxjava-scala/README.md

@@ -13,10 +13,30 @@ tasks.withType(ScalaCompile) {
 }
 
 sourceSets { 
+	main { 
+        scala { 
+            srcDir 'src/main/scala'
+        }
+    }
     test { 
         scala { 
             srcDir 'src/main/scala'
+            srcDir 'src/test/scala'
+            srcDir 'src/examples/scala'
+            srcDir 'src/examples/java'
+        }
+        java.srcDirs = []
+    }
+    examples {
+        // It seems that in Gradle, the dependency "compileScala depends on compileJava" is hardcoded,
+        // or at least not meant to be removed.
+        // However, compileScala also runs javac at the very end, so we just add the Java sources to
+        // the scala source set:
+        scala { 
+            srcDir 'src/examples/scala'
+            srcDir 'src/examples/java'
         }
+        java.srcDirs = []
     }
 }
 
@@ -34,6 +54,15 @@ tasks.compileScala {
     classpath = classpath + (configurations.compile + configurations.provided)
 }
 
+tasks.compileExamplesScala {  
+    classpath = classpath + files(compileScala.destinationDir) + (configurations.compile + configurations.provided)
+}
+
+// Add RxJava core to Scaladoc input:
+// tasks.scaladoc.source(project(':rxjava-core').tasks.getByPath(':rxjava-core:compileJava').source)
+// println("-------")
+// println(tasks.scaladoc.source.asPath)
+
 task test(overwrite: true, dependsOn: testClasses) << {
     ant.taskdef(name: 'scalatest',
             classname: 'org.scalatest.tools.ScalaTestAntTask',

language-adaptors/rxjava-scala/TODO.md

@@ -21,7 +21,8 @@ import rx.lang.scala._
 import scala.concurrent.duration._
 import org.junit.{Before, Test, Ignore}
 import org.junit.Assert._
-import rx.lang.scala.concurrency.NewThreadScheduler
+import rx.lang.scala.concurrency.Schedulers
+import java.io.IOException
 
 @Ignore // Since this doesn't do automatic testing, don't increase build time unnecessarily
 class RxScalaDemo extends JUnitSuite {
@@ -167,10 +168,10 @@ class RxScalaDemo extends JUnitSuite {
 
   @Test def schedulersExample() {
     val o = Observable.interval(100 millis).take(8)
-    o.observeOn(NewThreadScheduler).subscribe(
+    o.observeOn(Schedulers.newThread).subscribe(
         i => println(s"${i}a (on thread #${Thread.currentThread().getId()})")
     )
-    o.observeOn(NewThreadScheduler).subscribe(
+    o.observeOn(Schedulers.newThread).subscribe(
         i => println(s"${i}b (on thread #${Thread.currentThread().getId()})")
     )
     waitFor(o)
@@ -287,7 +288,7 @@ class RxScalaDemo extends JUnitSuite {
   // We can't put a general average method into Observable.scala, because Scala's Numeric
   // does not have scalar multiplication (we would need to calculate (1.0/numberOfElements)*sum)
   def doubleAverage(o: Observable[Double]): Observable[Double] = {
-    for ((finalSum, finalCount) <- o.fold((0.0, 0))({case ((sum, count), elem) => (sum+elem, count+1)}))
+    for ((finalSum, finalCount) <- o.foldLeft((0.0, 0))({case ((sum, count), elem) => (sum+elem, count+1)}))
       yield finalSum / finalCount
   }
 
@@ -321,13 +322,13 @@ class RxScalaDemo extends JUnitSuite {
         .toBlockingObservable.foreach(println(_))
   }
 
-  // source Observables are in a List:
-  @Test def zipManySeqExample() {
-    val observables = List(Observable(1, 2), Observable(10, 20), Observable(100, 200))
-    (for (seq <- Observable.zip(observables)) yield seq.mkString("(", ", ", ")"))
+  // source Observables are all known:
+  @Test def zip3Example() {
+    val o = Observable.zip(Observable(1, 2), Observable(10, 20), Observable(100, 200))
+    (for ((n1, n2, n3) <- o) yield s"$n1, $n2 and $n3")
         .toBlockingObservable.foreach(println(_))
   }
-  
+
   // source Observables are in an Observable:
   @Test def zipManyObservableExample() {
     val observables = Observable(Observable(1, 2), Observable(10, 20), Observable(100, 200))
@@ -375,6 +376,88 @@ class RxScalaDemo extends JUnitSuite {
     assertEquals(Seq(10, 9, 8, 7), Observable(10, 7, 8, 9).toSeq.map(_.sortWith(f)).toBlockingObservable.single)
   }
 
+  @Test def timestampExample() {
+    val timestamped = Observable.interval(100 millis).take(3).timestamp.toBlockingObservable
+    for ((millis, value) <- timestamped if value > 0) {
+      println(value + " at t = " + millis)
+    }
+  }
+  
+  @Test def materializeExample1() {
+    def printObservable[T](o: Observable[T]): Unit = {
+      import Notification._
+      o.materialize.subscribe(n => n match {
+        case OnNext(v) => println("Got value " + v)
+        case OnCompleted() => println("Completed")
+        case OnError(err) => println("Error: " + err.getMessage)
+      })
+    }
+    
+    val o1 = Observable.interval(100 millis).take(3)
+    val o2 = Observable(new IOException("Oops"))
+    printObservable(o1)
+    waitFor(o1)
+    printObservable(o2)
+    waitFor(o2)
+  }
+  
+  @Test def materializeExample2() {
+    import Notification._
+    Observable(1, 2, 3).materialize.subscribe(n => n match {
+      case OnNext(v) => println("Got value " + v)
+      case OnCompleted() => println("Completed")
+      case OnError(err) => println("Error: " + err.getMessage)
+    })
+  }
+  
+  @Test def elementAtReplacement() {
+    assertEquals("b", Observable("a", "b", "c").drop(1).first.toBlockingObservable.single)
+  }
+  
+  @Test def elementAtOrDefaultReplacement() {
+    assertEquals("b", Observable("a", "b", "c").drop(1).firstOrElse("!").toBlockingObservable.single)
+    assertEquals("!!", Observable("a", "b", "c").drop(10).firstOrElse("!!").toBlockingObservable.single)
+  }
+  
+  @Test def observableLikeFuture1() {
+    implicit val scheduler = Schedulers.threadPoolForIO
+    val o1 = observable {
+      Thread.sleep(1000)
+      5
+    }
+    val o2 = observable {
+      Thread.sleep(500)
+      4
+    }
+    Thread.sleep(500)
+    val t1 = System.currentTimeMillis
+    println((o1 merge o2).first.toBlockingObservable.single)
+    println(System.currentTimeMillis - t1)
+  }
+  
+  @Test def observableLikeFuture2() {
+    class Friend {}
+    val session = new Object {
+      def getFriends: List[Friend] = List(new Friend, new Friend)
+    }
+    
+    implicit val scheduler = Schedulers.threadPoolForIO
+    val o: Observable[List[Friend]] = observable {
+       session.getFriends
+    }
+    o.subscribe(
+      friendList => println(friendList),
+      err => println(err.getMessage)
+    )
+    
+    Thread.sleep(1500) // or convert to BlockingObservable
+  }
+
+  @Test def takeWhileWithIndexAlternative {
+    val condition = true
+    Observable("a", "b").zipWithIndex.takeWhile{case (elem, index) => condition}.map(_._1)
+  }
+
   def output(s: String): Unit = println(s)
 
   // blocks until obs has completed

language-adaptors/rxjava-scala/build.gradle

@@ -19,56 +19,52 @@ import java.{ lang => jlang }
 import rx.util.functions._
 
 /**
- * These function conversions convert between Scala functions and Rx Funcs and Actions.
- * Most users RxScala won't need them, but they might be useful if one wants to use
- * the rx.Observable directly instead of using rx.lang.scala.Observable or if one wants
- * to use a Java library taking/returning Funcs and Actions.
+ * These function conversions convert between Scala functions and Rx `Func`s and `Action`s.
+ * Most RxScala users won't need them, but they might be useful if one wants to use
+ * the `rx.Observable` directly instead of using `rx.lang.scala.Observable` or if one wants
+ * to use a Java library taking/returning `Func`s and `Action`s.
  */
 object ImplicitFunctionConversions {
   import language.implicitConversions
 
+  implicit def schedulerActionToFunc2[T](action: (Scheduler, T) => Subscription) =
+    new Func2[rx.Scheduler, T, Subscription] {
+      def call(s: rx.Scheduler, t: T): Subscription = {
+        action(s, t)
+      }
+    }  
+  
+  implicit def scalaSchedulerToJavaScheduler(s: Scheduler): rx.Scheduler = s.asJava
+  
+  implicit def javaSchedulerToScalaScheduler(s: rx.Scheduler): Scheduler = Scheduler(s)
+  
   implicit def scalaFunction1ToOnSubscribeFunc[T](f: rx.lang.scala.Observer[T] => Subscription) =
     new rx.Observable.OnSubscribeFunc[T] {
-      def onSubscribe(obs: Observer[_ >: T]): Subscription = {
+      def onSubscribe(obs: rx.Observer[_ >: T]): rx.Subscription = {
         f(obs)
       }
     }
 
-  /**
-   * Converts a by-name parameter to a Rx Func0
-   */
   implicit def scalaByNameParamToFunc0[B](param: => B): Func0[B] =
     new Func0[B] {
       def call(): B = param
     }
 
-  /**
-   * Converts 0-arg function to Rx Action0
-   */
   implicit def scalaFunction0ProducingUnitToAction0(f: (() => Unit)): Action0 =
     new Action0 {
       def call(): Unit = f()
     }
 
-  /**
-   * Converts 1-arg function to Rx Action1
-   */
   implicit def scalaFunction1ProducingUnitToAction1[A](f: (A => Unit)): Action1[A] =
     new Action1[A] {
       def call(a: A): Unit = f(a)
     }
 
-  /**
-   * Converts 1-arg predicate to Rx Func1[A, java.lang.Boolean]
-   */
   implicit def scalaBooleanFunction1ToRxBooleanFunc1[A](f: (A => Boolean)): Func1[A, jlang.Boolean] =
     new Func1[A, jlang.Boolean] {
       def call(a: A): jlang.Boolean = f(a).booleanValue
     }
 
-  /**
-   * Converts 2-arg predicate to Rx Func2[A, B, java.lang.Boolean]
-   */
   implicit def scalaBooleanFunction2ToRxBooleanFunc1[A, B](f: ((A, B) => Boolean)): Func2[A, B, jlang.Boolean] =
     new Func2[A, B, jlang.Boolean] {
       def call(a: A, b: B): jlang.Boolean = f(a, b).booleanValue
@@ -79,34 +75,21 @@ object ImplicitFunctionConversions {
       def call(args: java.lang.Object*): R = f(args)
     }
 
-  /**
-   * Converts a specific function shape (used in takeWhile) to the equivalent Java types with an Rx Func2
-   */
   implicit def convertTakeWhileFuncToRxFunc2[A](f: (A, Int) => Boolean): Func2[A, jlang.Integer, jlang.Boolean] =
     new Func2[A, jlang.Integer, jlang.Boolean] {
       def call(a: A, b: jlang.Integer): jlang.Boolean = f(a, b).booleanValue
     }
 
-  /**
-   * Converts a function shaped ilke compareTo into the equivalent Rx Func2
-   */
   implicit def convertComparisonFuncToRxFunc2[A](f: (A, A) => Int): Func2[A, A, jlang.Integer] =
     new Func2[A, A, jlang.Integer] {
       def call(a1: A, a2: A): jlang.Integer = f(a1, a2).intValue
     }
 
-  /**
-   * This implicit allows Scala code to use any exception type and still work
-   * with invariant Func1 interface
-   */
   implicit def exceptionFunction1ToRxExceptionFunc1[A <: Exception, B](f: (A => B)): Func1[Exception, B] =
     new Func1[Exception, B] {
       def call(ex: Exception): B = f(ex.asInstanceOf[A])
     }
 
-  /**
-   * The following implicits convert functions of different arities into the Rx equivalents
-   */
   implicit def scalaFunction0ToRxFunc0[A](f: () => A): Func0[A] =
     new Func0[A] {
       def call(): A = f()