Adding SwitchIfEmpty

docs/interfaces/IObservable.md

@@ -64,7 +64,7 @@ Observable.fromValues([1,2,3,4)
 	* [Contains](#contains)/[Every](#every)
 	* [SequenceEqual](#sequenceequal)
 	* [Amb](#amb)/[Race](#race)
-	* [DefaultIfEmpty](#defaultifempty)
+	* [DefaultIfEmpty](#defaultifempty)/[SwitchIfEmpty](#switchifempty)
 * [Math and Aggregation](#math-and-aggregation)
 	* [Reduce](#reduce)/[ReduceWithInitial](#reducewithinitial)
 	* [Count](#count)
@@ -1639,6 +1639,18 @@ Observable.empty()
 // Output: "A default value"
 ```
 
+<a name="switchifempty" href="#switchifempty">#</a> .**switchIfEmpty**(*`alternative:` [IObservable](#iobservable)\<[T](/docs/README.md#wildcard-class-notation)>*) returns [IObservable](#iobservable)\<[T](/docs/README.md#wildcard-class-notation)> [<>](/src/rx/operators/SwitchIfEmpty.mon  "Source")
+
+Switch to a different observable source if the main source completes without emitting any values.
+
+```javascript
+Observable.empty()
+	.switchIfEmpty(Observable.fromValues([1,2,3]))
+	...
+
+// Output: 1,2,3
+```
+
 ### Math and Aggregation
 
 <a name="reduce" href="#reduce">#</a> .**reduce**(*action<`aggregate:` [T2](/docs/README.md#wildcard-class-notation), `value:` [T1](/docs/README.md#wildcard-class-notation)> returns [T2](/docs/README.md#wildcard-class-notation)*) returns [IObservable](#iobservable)<[T2](/docs/README.md#wildcard-class-notation)> [<>](/src/rx/operators/Scan.mon  "Source")

src/rx/interfaces/IObservable.mon

@@ -143,4 +143,5 @@ event IObservable {
 	action<any> returns IObservable sort;
 	action<> returns IObservable sortAsc;
 	action<> returns IObservable sortDesc;
+	action<IObservable> returns IObservable switchIfEmpty;
 }

src/rx/interfaces/ISubject.mon

@@ -149,4 +149,5 @@ event ISubject {
 	action<any> returns IObservable sort;
 	action<> returns IObservable sortAsc;
 	action<> returns IObservable sortDesc;
+	action<IObservable> returns IObservable switchIfEmpty;
 }

src/rx/objects/BehaviorSubject.mon

@@ -40,11 +40,11 @@ event BehaviorSubject {
 	action asISubject() returns ISubject {
 		return ISubject(self,
 		                next, error, complete, asIObservable,
-		                observable.connectObserver, observable.subscribe, observable.map, observable.publish, observable.connect, observable.refCount, observable.share, observable.take, observable.takeLast, observable.first, observable.last, observable.skip, observable.skipLast, observable.filter, observable.scan, observable.scanWithInitial, observable.distinct, observable.distinctBy, observable.combineLatestFromInstance, observable.withLatestFrom, observable.delay, observable.async, observable.do, observable.publishReplay, observable.shareReplay, observable.takeUntil, observable.repeatObservable, observable.flatMap, observable.mergeFromInstance, observable.zipFromInstance, observable.switchOnNext, observable.skipUntil, observable.elementAt, observable.reduce, observable.reduceWithInitial, observable.toStream, observable.catchError, observable.retry, observable.observeOn, observable.groupBy, observable.observeToChannel, observable.observeOnNew, observable.every, observable.contains, observable.takeWhile, observable.skipWhile, observable.concatFromInstance, observable.startWith, observable.defaultIfEmpty, observable.ignoreElements, observable.count, observable.sum, observable.sumInteger, observable.sumFloat, observable.sumDecimal, observable.concatString, observable.max, observable.maxInteger, observable.maxFloat, observable.maxDecimal, observable.min, observable.minInteger, observable.minFloat, observable.minDecimal, observable.average, observable.averageDecimal, observable.sequenceEqualFromInstance, observable.ambFromInstance, observable.raceFromInstance, observable.timestamp, observable.updateTimestamp, observable.timeout, observable.getSync, observable.getSyncOr, observable.timeInterval, observable.distinctUntilChanged, observable.distinctByUntilChanged, observable.switchMap, observable.debounce, observable.windowTime, observable.throttleFirst, observable.throttleLast, observable.sampleTime, observable.buffer, observable.bufferTime, observable.bufferCount, observable.bufferTimeOrCount, observable.combineLatestToSequenceFromInstance, observable.withLatestFromToSequence, observable.zipToSequenceFromInstance, observable.groupByWindow, observable.windowCount, observable.windowTimeOrCount, observable.sample, observable.sampleCount, observable.sampleTimeOrCount, observable.bufferCountSkip, observable.pipe, observable.pluck, observable.mergeAll, observable.pipeOn, observable.pipeOnNew, observable.subscribeOn, observable.subscribeOnNew, observable.pairwise, observable.let, observable.groupByField, observable.complexPipe, observable.complexPipeOn, observable.complexPipeOnNew, observable.decouple, observable.distinctByField, observable.distinctByFieldUntilChanged, observable.pausable, observable.pausableBuffered, observable.toChannel, observable.toSortedList, observable.toSortedListAsc, observable.toSortedListDesc, observable.sort, observable.sortAsc, observable.sortDesc);
+		                observable.connectObserver, observable.subscribe, observable.map, observable.publish, observable.connect, observable.refCount, observable.share, observable.take, observable.takeLast, observable.first, observable.last, observable.skip, observable.skipLast, observable.filter, observable.scan, observable.scanWithInitial, observable.distinct, observable.distinctBy, observable.combineLatestFromInstance, observable.withLatestFrom, observable.delay, observable.async, observable.do, observable.publishReplay, observable.shareReplay, observable.takeUntil, observable.repeatObservable, observable.flatMap, observable.mergeFromInstance, observable.zipFromInstance, observable.switchOnNext, observable.skipUntil, observable.elementAt, observable.reduce, observable.reduceWithInitial, observable.toStream, observable.catchError, observable.retry, observable.observeOn, observable.groupBy, observable.observeToChannel, observable.observeOnNew, observable.every, observable.contains, observable.takeWhile, observable.skipWhile, observable.concatFromInstance, observable.startWith, observable.defaultIfEmpty, observable.ignoreElements, observable.count, observable.sum, observable.sumInteger, observable.sumFloat, observable.sumDecimal, observable.concatString, observable.max, observable.maxInteger, observable.maxFloat, observable.maxDecimal, observable.min, observable.minInteger, observable.minFloat, observable.minDecimal, observable.average, observable.averageDecimal, observable.sequenceEqualFromInstance, observable.ambFromInstance, observable.raceFromInstance, observable.timestamp, observable.updateTimestamp, observable.timeout, observable.getSync, observable.getSyncOr, observable.timeInterval, observable.distinctUntilChanged, observable.distinctByUntilChanged, observable.switchMap, observable.debounce, observable.windowTime, observable.throttleFirst, observable.throttleLast, observable.sampleTime, observable.buffer, observable.bufferTime, observable.bufferCount, observable.bufferTimeOrCount, observable.combineLatestToSequenceFromInstance, observable.withLatestFromToSequence, observable.zipToSequenceFromInstance, observable.groupByWindow, observable.windowCount, observable.windowTimeOrCount, observable.sample, observable.sampleCount, observable.sampleTimeOrCount, observable.bufferCountSkip, observable.pipe, observable.pluck, observable.mergeAll, observable.pipeOn, observable.pipeOnNew, observable.subscribeOn, observable.subscribeOnNew, observable.pairwise, observable.let, observable.groupByField, observable.complexPipe, observable.complexPipeOn, observable.complexPipeOnNew, observable.decouple, observable.distinctByField, observable.distinctByFieldUntilChanged, observable.pausable, observable.pausableBuffered, observable.toChannel, observable.toSortedList, observable.toSortedListAsc, observable.toSortedListDesc, observable.sort, observable.sortAsc, observable.sortDesc, observable.switchIfEmpty);
 	}
 
 	action asIObservable() returns IObservable {
 		return IObservable(self, 
-		                   observable.connectObserver, observable.subscribe, observable.map, observable.publish, observable.connect, observable.refCount, observable.share, observable.take, observable.takeLast, observable.first, observable.last, observable.skip, observable.skipLast, observable.filter, observable.scan, observable.scanWithInitial, observable.distinct, observable.distinctBy, observable.combineLatestFromInstance, observable.withLatestFrom, observable.delay, observable.async, observable.do, observable.publishReplay, observable.shareReplay, observable.takeUntil, observable.repeatObservable, observable.flatMap, observable.mergeFromInstance, observable.zipFromInstance, observable.switchOnNext, observable.skipUntil, observable.elementAt, observable.reduce, observable.reduceWithInitial, observable.toStream, observable.catchError, observable.retry, observable.observeOn, observable.groupBy, observable.observeToChannel, observable.observeOnNew, observable.every, observable.contains, observable.takeWhile, observable.skipWhile, observable.concatFromInstance, observable.startWith, observable.defaultIfEmpty, observable.ignoreElements, observable.count, observable.sum, observable.sumInteger, observable.sumFloat, observable.sumDecimal, observable.concatString, observable.max, observable.maxInteger, observable.maxFloat, observable.maxDecimal, observable.min, observable.minInteger, observable.minFloat, observable.minDecimal, observable.average, observable.averageDecimal, observable.sequenceEqualFromInstance, observable.ambFromInstance, observable.raceFromInstance, observable.timestamp, observable.updateTimestamp, observable.timeout, observable.getSync, observable.getSyncOr, observable.timeInterval, observable.distinctUntilChanged, observable.distinctByUntilChanged, observable.switchMap, observable.debounce, observable.windowTime, observable.throttleFirst, observable.throttleLast, observable.sampleTime, observable.buffer, observable.bufferTime, observable.bufferCount, observable.bufferTimeOrCount, observable.combineLatestToSequenceFromInstance, observable.withLatestFromToSequence, observable.zipToSequenceFromInstance, observable.groupByWindow, observable.windowCount, observable.windowTimeOrCount, observable.sample, observable.sampleCount, observable.sampleTimeOrCount, observable.bufferCountSkip, observable.pipe, observable.pluck, observable.mergeAll, observable.pipeOn, observable.pipeOnNew, observable.subscribeOn, observable.subscribeOnNew, observable.pairwise, observable.let, observable.groupByField, observable.complexPipe, observable.complexPipeOn, observable.complexPipeOnNew, observable.decouple, observable.distinctByField, observable.distinctByFieldUntilChanged, observable.pausable, observable.pausableBuffered, observable.toChannel, observable.toSortedList, observable.toSortedListAsc, observable.toSortedListDesc, observable.sort, observable.sortAsc, observable.sortDesc);
+		                   observable.connectObserver, observable.subscribe, observable.map, observable.publish, observable.connect, observable.refCount, observable.share, observable.take, observable.takeLast, observable.first, observable.last, observable.skip, observable.skipLast, observable.filter, observable.scan, observable.scanWithInitial, observable.distinct, observable.distinctBy, observable.combineLatestFromInstance, observable.withLatestFrom, observable.delay, observable.async, observable.do, observable.publishReplay, observable.shareReplay, observable.takeUntil, observable.repeatObservable, observable.flatMap, observable.mergeFromInstance, observable.zipFromInstance, observable.switchOnNext, observable.skipUntil, observable.elementAt, observable.reduce, observable.reduceWithInitial, observable.toStream, observable.catchError, observable.retry, observable.observeOn, observable.groupBy, observable.observeToChannel, observable.observeOnNew, observable.every, observable.contains, observable.takeWhile, observable.skipWhile, observable.concatFromInstance, observable.startWith, observable.defaultIfEmpty, observable.ignoreElements, observable.count, observable.sum, observable.sumInteger, observable.sumFloat, observable.sumDecimal, observable.concatString, observable.max, observable.maxInteger, observable.maxFloat, observable.maxDecimal, observable.min, observable.minInteger, observable.minFloat, observable.minDecimal, observable.average, observable.averageDecimal, observable.sequenceEqualFromInstance, observable.ambFromInstance, observable.raceFromInstance, observable.timestamp, observable.updateTimestamp, observable.timeout, observable.getSync, observable.getSyncOr, observable.timeInterval, observable.distinctUntilChanged, observable.distinctByUntilChanged, observable.switchMap, observable.debounce, observable.windowTime, observable.throttleFirst, observable.throttleLast, observable.sampleTime, observable.buffer, observable.bufferTime, observable.bufferCount, observable.bufferTimeOrCount, observable.combineLatestToSequenceFromInstance, observable.withLatestFromToSequence, observable.zipToSequenceFromInstance, observable.groupByWindow, observable.windowCount, observable.windowTimeOrCount, observable.sample, observable.sampleCount, observable.sampleTimeOrCount, observable.bufferCountSkip, observable.pipe, observable.pluck, observable.mergeAll, observable.pipeOn, observable.pipeOnNew, observable.subscribeOn, observable.subscribeOnNew, observable.pairwise, observable.let, observable.groupByField, observable.complexPipe, observable.complexPipeOn, observable.complexPipeOnNew, observable.decouple, observable.distinctByField, observable.distinctByFieldUntilChanged, observable.pausable, observable.pausableBuffered, observable.toChannel, observable.toSortedList, observable.toSortedListAsc, observable.toSortedListDesc, observable.sort, observable.sortAsc, observable.sortDesc, observable.switchIfEmpty);
 	}
 }

src/rx/objects/Observable.mon

@@ -102,6 +102,7 @@ using com.industry.rx_epl.operators.Sum;
 using com.industry.rx_epl.operators.SumDecimal;
 using com.industry.rx_epl.operators.SumFloat;
 using com.industry.rx_epl.operators.SumInteger;
+using com.industry.rx_epl.operators.SwitchIfEmpty;
 using com.industry.rx_epl.operators.SwitchMap;
 using com.industry.rx_epl.operators.SwitchOnNext;
 using com.industry.rx_epl.operators.Take;
@@ -1113,6 +1114,12 @@ event Observable {
 		return o.asIObservable();
 	}
 
+	action switchIfEmpty(IObservable alternative) returns IObservable {
+		Observable o := _create();
+		o.onConnection := SwitchIfEmpty.create(alternative)(onConnection);
+		return o.asIObservable();
+	}
+
 	static action invalidConnect() returns IDisposable {
 		throw Exception("Can only connect a published Observable", "UnsupportedOperation");
 	}
@@ -1127,6 +1134,6 @@ event Observable {
 
 	action asIObservable() returns IObservable {
 		return IObservable(self, 
-		                   connectObserver, subscribe, map, publish, connect, refCount, share, take, takeLast, first, last, skip, skipLast, filter, scan, scanWithInitial, distinct, distinctBy, combineLatestFromInstance, withLatestFrom, delay, async, do, publishReplay, shareReplay, takeUntil, repeatObservable, flatMap, mergeFromInstance, zipFromInstance, switchOnNext, skipUntil, elementAt, reduce, reduceWithInitial, toStream, catchError, retry, observeOn, groupBy, observeToChannel, observeOnNew, every, contains, takeWhile, skipWhile, concatFromInstance, startWith, defaultIfEmpty, ignoreElements, count, sum, sumInteger, sumFloat, sumDecimal, concatString, max, maxInteger, maxFloat, maxDecimal, min, minInteger, minFloat, minDecimal, average, averageDecimal, sequenceEqualFromInstance, ambFromInstance, raceFromInstance, timestamp, updateTimestamp, timeout, getSync, getSyncOr, timeInterval, distinctUntilChanged, distinctByUntilChanged, switchMap, debounce, windowTime, throttleFirst, throttleLast, sampleTime, buffer, bufferTime, bufferCount, bufferTimeOrCount, combineLatestToSequenceFromInstance, withLatestFromToSequence, zipToSequenceFromInstance, groupByWindow, windowCount, windowTimeOrCount, sample, sampleCount, sampleTimeOrCount, bufferCountSkip, pipe, pluck, mergeAll, pipeOn, pipeOnNew, subscribeOn, subscribeOnNew, pairwise, let, groupByField, complexPipe, complexPipeOn, complexPipeOnNew, decouple, distinctByField, distinctByFieldUntilChanged, pausable, pausableBuffered, toChannel, toSortedList, toSortedListAsc, toSortedListDesc, sort, sortAsc, sortDesc);
+		                   connectObserver, subscribe, map, publish, connect, refCount, share, take, takeLast, first, last, skip, skipLast, filter, scan, scanWithInitial, distinct, distinctBy, combineLatestFromInstance, withLatestFrom, delay, async, do, publishReplay, shareReplay, takeUntil, repeatObservable, flatMap, mergeFromInstance, zipFromInstance, switchOnNext, skipUntil, elementAt, reduce, reduceWithInitial, toStream, catchError, retry, observeOn, groupBy, observeToChannel, observeOnNew, every, contains, takeWhile, skipWhile, concatFromInstance, startWith, defaultIfEmpty, ignoreElements, count, sum, sumInteger, sumFloat, sumDecimal, concatString, max, maxInteger, maxFloat, maxDecimal, min, minInteger, minFloat, minDecimal, average, averageDecimal, sequenceEqualFromInstance, ambFromInstance, raceFromInstance, timestamp, updateTimestamp, timeout, getSync, getSyncOr, timeInterval, distinctUntilChanged, distinctByUntilChanged, switchMap, debounce, windowTime, throttleFirst, throttleLast, sampleTime, buffer, bufferTime, bufferCount, bufferTimeOrCount, combineLatestToSequenceFromInstance, withLatestFromToSequence, zipToSequenceFromInstance, groupByWindow, windowCount, windowTimeOrCount, sample, sampleCount, sampleTimeOrCount, bufferCountSkip, pipe, pluck, mergeAll, pipeOn, pipeOnNew, subscribeOn, subscribeOnNew, pairwise, let, groupByField, complexPipe, complexPipeOn, complexPipeOnNew, decouple, distinctByField, distinctByFieldUntilChanged, pausable, pausableBuffered, toChannel, toSortedList, toSortedListAsc, toSortedListDesc, sort, sortAsc, sortDesc, switchIfEmpty);
 	}
 }