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    • hu.akarnokd.rxjava2.internal.operators.OperatorSingle Maven / Gradle / Ivy

    There is a newer version: 2.0.0-RC3
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    /**
 * Copyright 2015 David Karnok and Netflix, Inc.
 * 
 * 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.rxjava2.internal.operators;

import java.util.NoSuchElementException;

import org.reactivestreams.*;

import hu.akarnokd.rxjava2.Observable.Operator;
import hu.akarnokd.rxjava2.internal.subscriptions.SubscriptionHelper;
import hu.akarnokd.rxjava2.plugins.RxJavaPlugins;

public final class OperatorSingle implements Operator {
    
    static final OperatorSingle NO_DEFAULT = new OperatorSingle(null);
    
    @SuppressWarnings("unchecked")
    public static  OperatorSingle instanceNoDefault() {
        return (OperatorSingle)NO_DEFAULT;
    }
    
    final T defaultValue;
    public OperatorSingle(T defaultValue) {
        this.defaultValue = defaultValue;
    }
    @Override
    public Subscriber apply(Subscriber t) {
        return new SingleElementSubscriber(t, defaultValue);
    }
    
    static final class SingleElementSubscriber implements Subscriber, Subscription {
        final Subscriber actual;
        final T defaultValue;
        
        Subscription s;
        
        T value;
        
        boolean done;
        
        public SingleElementSubscriber(Subscriber actual, T defaultValue) {
            this.actual = actual;
            this.defaultValue = defaultValue;
        }
        
        @Override
        public void onSubscribe(Subscription s) {
            if (this.s != null) {
                s.cancel();
                RxJavaPlugins.onError(new IllegalStateException("Subscription already set!"));
                return;
            }
            this.s = s;
            actual.onSubscribe(this);
        }
        
        @Override
        public void onNext(T t) {
            if (done) {
                return;
            }
            if (value != null) {
                done = true;
                s.cancel();
                actual.onError(new IllegalArgumentException("Sequence contains more than one element!"));
                return;
            }
            value = t;
        }
        
        @Override
        public void onError(Throwable t) {
            if (done) {
                return;
            }
            done = true;
            actual.onError(t);
        }
        
        @Override
        public void onComplete() {
            if (done) {
                return;
            }
            done = true;
            T v = value;
            value = null;
            if (v == null) {
                v = defaultValue;
            }
            if (v == null) {
                actual.onError(new NoSuchElementException());
            } else {
                actual.onNext(v);
                actual.onComplete();
            }
        }
        
        @Override
        public void request(long n) {
            if (SubscriptionHelper.validateRequest(n)) {
                return;
            }
            s.request(Long.MAX_VALUE);
        }
        
        @Override
        public void cancel() {
            s.cancel();
        }
    }
}
    
    
    
    

    




    
    
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