001/*
002 * (C) Copyright 2006-2011 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *     bstefanescu
018 */
019package org.nuxeo.ecm.webengine.jaxrs.servlet;
020
021import java.util.Enumeration;
022import java.util.NoSuchElementException;
023
024/**
025 * @author <a href="mailto:[email protected]">Bogdan Stefanescu</a>
026 */
027public class CompoundEnumeration<E> implements Enumeration<E> {
028
029    private final Enumeration<E>[] enums;
030
031    private int index = 0;
032
033    @SuppressWarnings("unchecked")
034    public CompoundEnumeration(Enumeration<?>[] enums) {
035        this.enums = (Enumeration<E>[]) enums;
036    }
037
038    private boolean next() {
039        while (index < enums.length) {
040            if (enums[index] != null && enums[index].hasMoreElements()) {
041                return true;
042            }
043            index++;
044        }
045        return false;
046    }
047
048    @Override
049    public boolean hasMoreElements() {
050        return next();
051    }
052
053    @Override
054    public E nextElement() {
055        if (!next()) {
056            throw new NoSuchElementException();
057        }
058        return enums[index].nextElement();
059    }
060
061}