/*

 * Copyright (c) 2001, 2005, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.util;

import java.util.Enumeration;

import java.util.Iterator;

import java.util.NoSuchElementException;

import java.util.Set;

/**

 * Implements an Enumeration that combines elements from a Set and

 * an Enumeration. Used by ListResourceBundle and PropertyResourceBundle.

 */

public class ResourceBundleEnumeration implements Enumeration<String> {

    Set<String> set;

    Iterator<String> iterator;

    Enumeration<String> enumeration; // may remain null

    /**

     * Constructs a resource bundle enumeration.

     * @param set an set providing some elements of the enumeration

     * @param enumeration an enumeration providing more elements of the enumeration.

     *        enumeration may be null.

     */

    public ResourceBundleEnumeration(Set<String> set, Enumeration<String> enumeration) {

        this.set = set;

        this.iterator = set.iterator();

        this.enumeration = enumeration;

    }

    String next = null;

    public boolean hasMoreElements() {

        if (next == null) {

            if (iterator.hasNext()) {

                next = iterator.next();

            } else if (enumeration != null) {

                while (next == null && enumeration.hasMoreElements()) {

                    next = enumeration.nextElement();

                    if (set.contains(next)) {

                        next = null;

                    }

                }

            }

        }

        return next != null;

    }

    public String nextElement() {

        if (hasMoreElements()) {

            String result = next;

            next = null;

            return result;

        } else {

            throw new NoSuchElementException();

        }

    }

}