hu.akarnokd.rxjava.interop.SubjectV2ToSubjectV1 Maven / Gradle / Ivy

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rxjava2-interop developed by David Karnok
There is a newer version: 0.13.7
/*
 * Copyright 2016 David Karnok
 *
 * 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 hu.akarnokd.rxjava.interop;

import java.util.concurrent.atomic.*;

/**
 * Wrap a 2.x Subject into a 1.x Subject.
 * @param  the input and output value type
 * @since 0.9.0
 */
final class SubjectV2ToSubjectV1 extends rx.subjects.Subject {

    static  rx.subjects.Subject createWith(io.reactivex.subjects.Subject subject) {
        State state = new State(subject);
        return new SubjectV2ToSubjectV1(state);
    }

    final State state;

    private SubjectV2ToSubjectV1(State state) {
        super(state);
        this.state = state;
    }

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

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

    @Override
    public void onCompleted() {
        state.onCompleted();
    }

    @Override
    public boolean hasObservers() {
        return state.hasObservers();
    }

    static final class State
    implements rx.Observable.OnSubscribe {

        final io.reactivex.subjects.Subject subject;

        State(io.reactivex.subjects.Subject subject) {
            this.subject = subject;
        }

        @Override
        public void call(rx.Subscriber t) {
            SourceObserver parent = new SourceObserver(t);

            t.add(parent);
            t.setProducer(parent);

            subject.subscribe(parent);
        }

        void onNext(T t) {
            subject.onNext(t);
        }

        void onError(Throwable e) {
            subject.onError(e);
        }

        void onCompleted() {
            subject.onComplete();
        }

        boolean hasObservers() {
            return subject.hasObservers();
        }
    }

    static final class SourceObserver
    extends AtomicReference
    implements io.reactivex.Observer, rx.Subscription, rx.Producer {

        private static final long serialVersionUID = -6567012932544037069L;

        final rx.Subscriber actual;

        final AtomicLong requested;

        SourceObserver(rx.Subscriber actual) {
            this.actual = actual;
            this.requested = new AtomicLong();
        }

        @Override
        public void request(long n) {
            if (n > 0L) {
                io.reactivex.internal.util.BackpressureHelper.add(requested, n);
            }
        }

        @Override
        public void unsubscribe() {
            io.reactivex.internal.disposables.DisposableHelper.dispose(this);
        }

        @Override
        public boolean isUnsubscribed() {
            return io.reactivex.internal.disposables.DisposableHelper.isDisposed(get());
        }

        @Override
        public void onSubscribe(io.reactivex.disposables.Disposable d) {
            io.reactivex.internal.disposables.DisposableHelper.setOnce(this, d);
        }

        @Override
        public void onNext(T t) {
            if (requested.get() != 0) {
                actual.onNext(t);
                io.reactivex.internal.util.BackpressureHelper.produced(requested, 1);
            } else {
                unsubscribe();
                actual.onError(new rx.exceptions.MissingBackpressureException());
            }
        }

        @Override
        public void onError(Throwable t) {
            lazySet(io.reactivex.internal.disposables.DisposableHelper.DISPOSED);
            actual.onError(t);
        }

        @Override
        public void onComplete() {
            lazySet(io.reactivex.internal.disposables.DisposableHelper.DISPOSED);
            actual.onCompleted();
        }
    }
}