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.observable;

import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.internal.disposables.DisposableHelper;
import io.reactivex.internal.util.EmptyComponent;

Breaks the links between the upstream and the downstream (the Disposable and
the Observer references) when the sequence terminates or gets disposed.
Type parameters:
<T> – the value type/**
 * Breaks the links between the upstream and the downstream (the Disposable and
 * the Observer references) when the sequence terminates or gets disposed.
 *
 * @param <T> the value type
 */
public final class ObservableDetach<T> extends AbstractObservableWithUpstream<T, T> {

    public ObservableDetach(ObservableSource<T> source) {
        super(source);
    }

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

    static final class DetachObserver<T> implements Observer<T>, Disposable {

        Observer<? super T> downstream;

        Disposable upstream;

        DetachObserver(Observer<? super T> downstream) {
            this.downstream = downstream;
        }

        @Override
        public void dispose() {
            Disposable d = this.upstream;
            this.upstream = EmptyComponent.INSTANCE;
            this.downstream = EmptyComponent.asObserver();
            d.dispose();
        }

        @Override
        public boolean isDisposed() {
            return upstream.isDisposed();
        }

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

                downstream.onSubscribe(this);
            }
        }

        @Override
        public void onNext(T t) {
            downstream.onNext(t);
        }

        @Override
        public void onError(Throwable t) {
            Observer<? super T> a = downstream;
            this.upstream = EmptyComponent.INSTANCE;
            this.downstream = EmptyComponent.asObserver();
            a.onError(t);
        }

        @Override
        public void onComplete() {
            Observer<? super T> a = downstream;
            this.upstream = EmptyComponent.INSTANCE;
            this.downstream = EmptyComponent.asObserver();
            a.onComplete();
        }
    }
}