CompositeDifferentiator.java

/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.utility.diff;

import java.util.Collection;

import org.eclipse.persistence.tools.workbench.utility.string.StringTools;


/**
 * Delegate behavior to the component differentiators,
 * and gather up the results in a composite diff.
 */
public class CompositeDifferentiator implements Differentiator {
    /** the component differentiators */
    private final Differentiator[] differentiators;

    /** calculated from the component differentiators */
    private final boolean comparesValueObjects;


    public CompositeDifferentiator(Collection differentiators) {
        this((Differentiator[]) differentiators.toArray(new Differentiator[differentiators.size()]));
    }

    public CompositeDifferentiator(Differentiator[] differentiators) {
        super();
        this.differentiators = differentiators;
        this.comparesValueObjects = this.buildcomparesValueObjects();
    }

    private boolean buildcomparesValueObjects() {
        int len = this.differentiators.length;
        if (len == 0) {
            return false;        // the default is 'false'
        }
        // make sure all the components match
        boolean result = this.differentiators[len - 1].comparesValueObjects();
        for (int i =len - 1; i-- > 0; ) {
            if (this.differentiators[i].comparesValueObjects() != result) {
                throw new IllegalStateException("all the component differentiators must match on Differentiator.comparesValueObjects()");
            }
        }
        return result;
    }

    /**
     * @see Differentiator#diff(Object, Object)
     */
    public Diff diff(Object object1, Object object2) {
        return this.diff(object1, object2, DifferentiatorAdapter.NORMAL);
    }

    /**
     * @see Differentiator#keyDiff(Object, Object)
     */
    public Diff keyDiff(Object object1, Object object2) {
        return this.diff(object1, object2, DifferentiatorAdapter.KEY);
    }

    private Diff diff(Object object1, Object object2, DifferentiatorAdapter adapter) {
        int len = this.differentiators.length;
        Diff[] diffs = new Diff[len];
        for (int i = 0; i < len; i++) {
            diffs[i] = adapter.diff(this.differentiators[i], object1, object2);
        }
        return new CompositeDiff(object1, object2, diffs, this);
    }

    /**
     * @see Differentiator#comparesValueObjects()
     */
    public boolean comparesValueObjects() {
        return this.comparesValueObjects;
    }

    /**
     * @see Object#toString()
     */
    public String toString() {
        return StringTools.buildToStringFor(this);
    }

}