eu.esdihumboldt.util.StructuredEquals.java Source code

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Here is the source code for eu.esdihumboldt.util.StructuredEquals.java

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/*
 * Copyright (c) 2012 Data Harmonisation Panel
 * 
 * All rights reserved. This program and the accompanying materials are made
 * available under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the License,
 * or (at your option) any later version.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution. If not, see <http://www.gnu.org/licenses/>.
 * 
 * Contributors:
 *     HUMBOLDT EU Integrated Project #030962
 *     Data Harmonisation Panel <http://www.dhpanel.eu>
 */

package eu.esdihumboldt.util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.NoSuchElementException;

import com.google.common.base.Objects;
import com.google.common.collect.Iterables;

/**
 * StructuredEquals provides methods for equals and hashCode implementations for
 * complex structures.
 * 
 * @author Simon Templer
 */
public class StructuredEquals {

    /**
     * Determines if the given objects are equal, in turn descending into
     * {@link Iterable}s and arrays and checking if the elements are equal (in
     * order).
     * 
     * @param o1 the first object
     * @param o2 the second object
     * @return if both objects are equal
     * @see #deepIterableHashCode(Object)
     */
    public boolean deepIterableEquals(Object o1, Object o2) {
        if (o1 == o2) {
            return true;
        }

        Iterable<?> iterable1 = asIterable(o1);
        Iterable<?> iterable2 = asIterable(o2);
        if (iterable1 != null && iterable2 != null) {
            if (Iterables.size(iterable1) == Iterables.size(iterable2)) { // size
                // check
                Iterator<?> it1 = iterable1.iterator();
                Iterator<?> it2 = iterable2.iterator();
                while (it1.hasNext() || it2.hasNext()) {
                    try {
                        if (!deepIterableEquals(it1.next(), it2.next())) {
                            return false;
                        }
                    } catch (NoSuchElementException e) {
                        return false;
                    }
                }

                return true;
            }

            return false;
        } else {
            return Objects.equal(o1, o2);
        }
    }

    /**
     * Get the hash code for all contained objects, descending into
     * {@link Iterable}s and arrays.
     * 
     * @param object the object to determine the hash code from
     * @return the hash code
     * @see #deepIterableEquals(Object, Object)
     */
    public int deepIterableHashCode(Object object) {
        return Arrays.hashCode(collectObjects(object).toArray());
    }

    /**
     * Collect all objects contained in an {@link Iterable} or array and in
     * their elements.
     * 
     * @param object the object to collect objects on
     * @return the collected objects
     */
    public Collection<?> collectObjects(Object object) {
        Iterable<?> iterable = asIterable(object);
        if (iterable == null) {
            return Collections.singleton(object);
        } else {
            Collection<Object> result = new ArrayList<Object>();
            for (Object child : iterable) {
                result.addAll(collectObjects(child));
            }
            return result;
        }
    }

    /**
     * Returns an iterable for the given objects contents, or null if it does
     * not contain anything that needs to be compared.
     * 
     * @param object the object in question
     * @return an iterable for the given object
     */
    protected Iterable<?> asIterable(Object object) {
        if (object == null)
            return null;
        if (object instanceof Iterable<?>) {
            return (Iterable<?>) object;
        }
        if (object.getClass().isArray()) {
            return Arrays.asList((Object[]) object);
        }
        return null;
    }
}