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rxjava2-extensions developed by David Karnok

There is a newer version: 0.20.10

/*
 * Copyright 2016-2017 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.rxjava2.joins;

import java.util.Map;

import io.reactivex.*;
import io.reactivex.functions.Consumer;

/**
 * Represents an execution plan for join patterns.
 * @param  the result type
 */
public abstract class Plan {
    abstract ActivePlan0 activate(Map externalSubscriptions,
            Observer observer, Consumer deactivate);

    @SuppressWarnings("unchecked")
    static final  JoinObserver1 createObserver(
            Map externalSubscriptions,
            Observable observable,
            Consumer onError
            ) {
        JoinObserver1 observer;
        JoinObserver nonGeneric = externalSubscriptions.get(observable);
        if (nonGeneric == null) {
            observer = new JoinObserver1(observable, onError);
            externalSubscriptions.put(observable, observer);
        } else {
            observer = (JoinObserver1) nonGeneric;
        }
        return observer;
    }

    /**
     * Extracts a method reference to the Observer's {@link Observer#onError(java.lang.Throwable) onError}
     * method in the form of an {@link Consumer}.
     * Java 8: observer::onError
     *
     * @param  the value type
     * @param observer
     *            the {@link Observer} to use
     * @return an action which calls observer's {@code onError} method.
     */
    protected static  Consumer onErrorFrom(final Observer observer) {
        return new Consumer() {
            @Override
            public void accept(Throwable t1) {
                observer.onError(t1);
            }
        };
    }

}