Implement CompositeObservable

Author: thomasnield

src/main/java/rx/javafx/sources/CompositeObservable.java

@@ -0,0 +1,62 @@
+/**
+ * Copyright 2016 Netflix, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package rx.javafx.sources;
+
+import javafx.collections.FXCollections;
+import javafx.collections.ObservableList;
+import rx.Observable;
+import rx.observables.JavaFxObservable;
+
+/**
+ * A CompositeObservable can merge multiple Observables that can be added/removed at any time,
+ * affecting all Subscribers regardless of when they subscribed. This is especailly helpful for merging
+ * multiple UI event sources.
+ * @param <T>
+ */
+public final class CompositeObservable<T> {
+
+    private final ObservableList<Observable<T>> sources;
+    private final Observable<T> observable;
+
+    public CompositeObservable() {
+        this(-1);
+    }
+
+    public CompositeObservable(int initialCapacity) {
+        sources = FXCollections.synchronizedObservableList(FXCollections.observableArrayList());
+
+        Observable<T> observable = JavaFxObservable.fromObservableList(sources)
+                .switchMap(list -> Observable.from(list).flatMap((Observable<T> obs) -> obs));
+
+        if (initialCapacity > 0) {
+            this.observable = observable.cacheWithInitialCapacity(initialCapacity);
+        }
+        else {
+            this.observable = observable;
+        }
+    }
+
+    public Observable<T> toObservable() {
+        return observable;
+    }
+
+    public void add(Observable<T> observable) {
+        sources.add(observable);
+    }
+    public void remove(Observable<T> observable) {
+        sources.remove(observable);
+    }
+}