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.maybe;

import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.internal.disposables.DisposableHelper;
import io.reactivex.internal.fuseable.HasUpstreamMaybeSource;
import io.reactivex.internal.observers.DeferredScalarDisposable;

Wraps a MaybeSource and exposes it as an Observable, relaying signals in a backpressure-aware manner
and composes cancellation through.
Type parameters:
<T> – the value type/**
 * Wraps a MaybeSource and exposes it as an Observable, relaying signals in a backpressure-aware manner
 * and composes cancellation through.
 *
 * @param <T> the value type
 */
public final class MaybeToObservable<T> extends Observable<T> implements HasUpstreamMaybeSource<T> {

    final MaybeSource<T> source;

    public MaybeToObservable(MaybeSource<T> source) {
        this.source = source;
    }

    @Override
    public MaybeSource<T> source() {
        return source;
    }

    @Override
    protected void subscribeActual(Observer<? super T> observer) {
        source.subscribe(create(observer));
    }

    
Creates a MaybeObserver wrapper around a Observer. 
History: 2.1.11 - experimental
Params:
downstream – the downstream Observer to talk to
Type parameters:
<T> – the value type
Returns:
the new MaybeObserver instance
Since:
2.2/**
     * Creates a {@link MaybeObserver} wrapper around a {@link Observer}.
     * <p>History: 2.1.11 - experimental
     * @param <T> the value type
     * @param downstream the downstream {@code Observer} to talk to
     * @return the new MaybeObserver instance
     * @since 2.2
     */
    public static <T> MaybeObserver<T> create(Observer<? super T> downstream) {
        return new MaybeToObservableObserver<T>(downstream);
    }

    static final class MaybeToObservableObserver<T> extends DeferredScalarDisposable<T>
    implements MaybeObserver<T> {

        private static final long serialVersionUID = 7603343402964826922L;

        Disposable upstream;

        MaybeToObservableObserver(Observer<? 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) {
            error(e);
        }

        @Override
        public void onComplete() {
            complete();
        }

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