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;

Signals true if the source Maybe signals onComplete, signals false if the source Maybe
signals onSuccess.
Type parameters:
<T> – the value type/**
 * Signals true if the source Maybe signals onComplete, signals false if the source Maybe
 * signals onSuccess.
 * 
 * @param <T> the value type
 */
public final class MaybeIsEmpty<T> extends AbstractMaybeWithUpstream<T, Boolean> {

    public MaybeIsEmpty(MaybeSource<T> source) {
        super(source);
    }

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

    static final class IsEmptyMaybeObserver<T>
    implements MaybeObserver<T>, Disposable {

        final MaybeObserver<? super Boolean> downstream;

        Disposable upstream;

        IsEmptyMaybeObserver(MaybeObserver<? super Boolean> downstream) {
            this.downstream = downstream;
        }

        @Override
        public void dispose() {
            upstream.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 onSuccess(T value) {
            downstream.onSuccess(false);
        }

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

        @Override
        public void onComplete() {
            downstream.onSuccess(true);
        }
    }
}