Copyright (c) 2016-present, RxJava Contributors.
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.
/**
 * Copyright (c) 2016-present, RxJava Contributors.
 *
 * 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 io.reactivex.internal.operators.flowable;

import org.reactivestreams.Subscriber;

import io.reactivex.Flowable;
import io.reactivex.internal.fuseable.ScalarCallable;
import io.reactivex.internal.subscriptions.EmptySubscription;

A source Flowable that signals an onSubscribe() + onComplete() only.
/**
 * A source Flowable that signals an onSubscribe() + onComplete() only.
 */
public final class FlowableEmpty extends Flowable<Object> implements ScalarCallable<Object> {

    public static final Flowable<Object> INSTANCE = new FlowableEmpty();

    private FlowableEmpty() {
    }

    @Override
    public void subscribeActual(Subscriber<? super Object> s) {
        EmptySubscription.complete(s);
    }

    @Override
    public Object call() {
        return null; // null scalar is interpreted as being empty
    }
}