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.single;

import org.reactivestreams.Subscriber;

import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.internal.disposables.DisposableHelper;
import io.reactivex.internal.subscriptions.DeferredScalarSubscription;

Wraps a Single and exposes it as a Flowable.
Type parameters:
<T> – the value type/**
 * Wraps a Single and exposes it as a Flowable.
 *
 * @param <T> the value type
 */
public final class SingleToFlowable<T> extends Flowable<T> {

    final SingleSource<? extends T> source;

    public SingleToFlowable(SingleSource<? extends T> source) {
        this.source = source;
    }

    @Override
    public void subscribeActual(final Subscriber<? super T> s) {
        source.subscribe(new SingleToFlowableObserver<T>(s));
    }

    static final class SingleToFlowableObserver<T> extends DeferredScalarSubscription<T>
    implements SingleObserver<T> {

        private static final long serialVersionUID = 187782011903685568L;

        Disposable upstream;

        SingleToFlowableObserver(Subscriber<? super T> downstream) {
            super(downstream);
        }

        @Override
        public void onSubscribe(Disposable d) {
            if (DisposableHelper.validate(this.upstream, d)) {
                this.upstream = d;

                downstream.onSubscribe(this);
            }
        }

        @Override
        public void onSuccess(T value) {
            complete(value);
        }

        @Override
        public void onError(Throwable e) {
            downstream.onError(e);
        }

        @Override
        public void cancel() {
            super.cancel();
            upstream.dispose();
        }
    }
}