net.femtoparsec.remote.Views.java Source code

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Here is the source code for net.femtoparsec.remote.Views.java

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/*
 * Copyright (c) 2014, Bastien Aracil
 * All rights reserved.
 * New BSD license. See http://en.wikipedia.org/wiki/Bsd_license
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *    * Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *    * Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *    * The name of Bastien Aracil may not be used to endorse or promote products
 *      derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL BASTIEN ARACIL BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package net.femtoparsec.remote;

import com.google.common.collect.ImmutableSet;
import net.femtoparsec.remote.impl.DefaultViewDifference;

import java.util.HashSet;
import java.util.Objects;
import java.util.Set;

/**
 * Utility class for {@link View}
 *
 * @author Bastien Aracil
 * @version 29/04/2014 - 16:05:30
 */
public class Views {

    /**
     * <p>Compute and return the difference between two views (members in both view, members in the first view only, and members in the second view only).
     * It is called difference since it assumes that the first view if chronologically before the second view.</p>
     *
     * @param first the first view
     * @param second the second view
     * @return the view difference
     */
    public static ViewDifference getDifference(View first, View second) {
        Objects.requireNonNull(second, "to");

        final DefaultViewDifference.Builder builder = DefaultViewDifference.builder();

        builder.setFrom(first).setTo(second);

        Set<Address> leftMembers = new HashSet<>();

        if (first != null) {
            //assume that all members have left the view
            leftMembers.addAll(first.getMembers());
        }

        ImmutableSet.Builder<Address> newMembersBuilder = ImmutableSet.builder();
        ImmutableSet.Builder<Address> unchangedMembersBuilder = ImmutableSet.builder();

        for (Address member : second) {
            if (leftMembers.remove(member)) {
                unchangedMembersBuilder.add(member);
            } else {
                newMembersBuilder.add(member);
            }
        }

        builder.setLeftMembers(ImmutableSet.copyOf(leftMembers)).setNewMembers(newMembersBuilder.build())
                .setUnchangedMembers(unchangedMembersBuilder.build());

        return builder.build();
    }

    private Views() throws IllegalAccessException {
        throw new IllegalAccessException("Cannot instantiate utility class " + this.getClass());
    }
}