feat(join): add join observable

Author: tusharmath

src/operators/Join.ts

@@ -0,0 +1,86 @@
+/**
+ * Created by tushar.mathur on 10/10/16.
+ */
+
+
+import {IObservable} from '../types/core/IObservable';
+import {IObserver} from '../types/core/IObserver';
+import {IScheduler} from '../types/IScheduler';
+import {ISubscription} from '../types/core/ISubscription';
+import {CompositeSubscription} from '../testing/Subscription';
+
+
+export class JoinValueObserver<T> implements IObserver<T> {
+  constructor (private sink: IObserver<T>, private root: JoinObserver<T>) {
+  }
+
+  next (val: T): void {
+    this.sink.next(val)
+  }
+
+  error (err: Error): void {
+    this.sink.error(err)
+  }
+
+  complete (): void {
+    this.root.subscriptionCompleted()
+  }
+
+}
+
+export class JoinObserver<T> implements IObserver<IObservable<T>> {
+  private count: number;
+  private sourceCompleted: boolean;
+
+  constructor (private sink: IObserver<T>, private scheduler: IScheduler, private subscriptions: CompositeSubscription) {
+    this.sourceCompleted = false
+    this.count = 0
+  }
+
+  subscriptionCompleted () {
+    this.count--
+    this.completeSink()
+  }
+
+  completeSink () {
+    if (this.sourceCompleted && this.count === 0) {
+      this.sink.complete()
+    }
+  }
+
+
+  next (val: IObservable<T>): void {
+    const joinValueObserver = new JoinValueObserver(this.sink, this);
+    this.count++
+    this.subscriptions.add(
+      val.subscribe(joinValueObserver, this.scheduler)
+    )
+  }
+
+  error (err: Error): void {
+    this.sink.error(err)
+  }
+
+  complete (): void {
+    this.sourceCompleted = true
+    this.completeSink()
+  }
+}
+
+
+export class JoinObservable<T> implements IObservable<T> {
+  constructor (private source: IObservable<IObservable<T>>) {
+  }
+
+  subscribe (observer: IObserver<T>, scheduler: IScheduler): ISubscription {
+    const subscription = new CompositeSubscription()
+    subscription.add(
+      this.source.subscribe(new JoinObserver(observer, scheduler, subscription), scheduler)
+    )
+    return subscription
+  }
+}
+
+export function join <T> (source: IObservable<IObservable<T>>) {
+  return new JoinObservable(source)
+}

test/test.JoinObservable.ts

@@ -0,0 +1,41 @@
+/**
+ * Created by tushar.mathur on 10/10/16.
+ */
+
+import test from 'ava';
+import {join} from '../src/operators/Join';
+import {TestScheduler} from '../src/testing/TestScheduler';
+import {ReactiveTest} from '../src/testing/ReactiveTest';
+const {next, complete} = ReactiveTest
+
+test('subscribe()', t => {
+  const sh = TestScheduler.of()
+  const sa$$ = sh.createColdObservable([
+    next(10, 'A0'),
+    next(20, 'A1'),
+    next(30, 'A2'),
+    complete(40)
+  ])
+  const sb$$ = sh.createColdObservable([
+    next(10, 'B0'),
+    next(20, 'B1'),
+    next(30, 'B2'),
+    complete(40)
+  ])
+  const s$$ = sh.createColdObservable([
+    next(10, sa$$),
+    next(20, sb$$),
+    complete(100)
+  ])
+  const {results} = sh.startScheduler<number>(() => join(s$$))
+
+  t.deepEqual(results, [
+    next(220, 'A0'),
+    next(230, 'A1'),
+    next(230, 'B0'),
+    next(240, 'A2'),
+    next(240, 'B1'),
+    next(250, 'B2'),
+    complete(300)
+  ])
+})