CompoundFilter.java

/*******************************************************************************
 * Copyright (c) 2006, 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
 *
 ******************************************************************************/
package org.eclipse.persistence.jpa.jpql.tools.utility.filter;

import java.io.Serializable;
import org.eclipse.persistence.jpa.jpql.utility.filter.Filter;

/**
 * This filter provides a simple framework for combining the behavior of a pair of filters.
 *
 * @version 2.3
 * @since 2.3
 */
@SuppressWarnings("nls")
public abstract class CompoundFilter<T> implements Filter<T>,
                                                   Cloneable,
                                                   Serializable {

    /**
     * The first {@link Filter} used to accept the value.
     */
    protected final Filter<T> filter1;

    /**
     * The second {@link Filter} used to accept the value.
     */
    protected final Filter<T> filter2;

    /**
     * The version number of this class which is used during deserialization to verify that the
     * sender and receiver of a serialized object have loaded classes for that object that are
     * compatible with respect to serialization.
     */
    private static final long serialVersionUID = 1L;

    /**
     * Creates a new <code>CompoundFilter</code> that will "accept" any object that is accept by both
     * of the specified wrapped filters.
     *
     * @param filter1 The first <code>Filter</code> used to accept the value
     * @param filter2 The second <code>Filter</code> used to accept the value
     */
    protected CompoundFilter(Filter<T> filter1, Filter<T> filter2) {
        super();

        checkFilter1(filter1);
        checkFilter2(filter2);

        this.filter1 = filter1;
        this.filter2 = filter2;
    }

    private void checkFilter1(Filter<T> filter) {
        if (filter == null) {
            throw new IllegalArgumentException("The first Filter cannot be null");
        }
    }

    private void checkFilter2(Filter<T> filter) {
        if (filter == null) {
            throw new IllegalArgumentException("The second Filter cannot be null");
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    @SuppressWarnings("unchecked")
    public CompoundFilter<T> clone() {
        try {
            return (CompoundFilter<T>) super.clone();
        }
        catch (CloneNotSupportedException e) {
            throw new RuntimeException("The cloning of this " + getClass().getSimpleName() + " was not successful.", e);
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean equals(Object object) {
        if (!(object instanceof CompoundFilter<?>)) {
            return false;
        }

        CompoundFilter<?> other = (CompoundFilter<?>) object;

        return (filter1.equals(other.filter1) && filter2.equals(other.filter2)) ||
               (filter1.equals(other.filter2) && filter2.equals(other.filter1));
    }

    /**
     * Returns the left <code>Filter</code> of this compound filter.
     *
     * @return The first <code>Filter</code>
     */
    public Filter<T> getFilter1() {
        return filter1;
    }

    /**
     * Returns the second <code>Filter</code> of this compound filter.
     *
     * @return The second <code>Filter</code>
     */
    public Filter<T> getFilter2() {
        return filter2;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int hashCode() {
        return filter1.hashCode() ^ filter2.hashCode();
    }

    /**
     * Returns a string representation of the filter's operator.
     *
     * @return The string value of the operator
     */
    protected abstract String operatorString();

    /**
     * {@inheritDoc}
     */
    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append(getClass().getSimpleName());
        sb.append(" (filter1=");
        sb.append(filter1);
        sb.append(", filter2=");
        sb.append(filter2);
        sb.append(")");
        return sb.toString();
    }
}