001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      https://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.collections4.iterators;
018
019import java.util.Iterator;
020import java.util.NoSuchElementException;
021import java.util.Objects;
022
023import org.w3c.dom.Node;
024import org.w3c.dom.NodeList;
025
026/**
027 * An {@link Iterator} over a {@link NodeList}.
028 * <p>
029 * This iterator does not support {@link #remove()} as a {@link NodeList} does not support
030 * removal of items.
031 * </p>
032 *
033 * @since 4.0
034 * @see NodeList
035 */
036public class NodeListIterator implements Iterator<Node> {
037
038    /** The original NodeList instance */
039    private final NodeList nodeList;
040
041    /** The current iterator index */
042    private int index;
043
044    /**
045     * Convenience constructor, which creates a new NodeListIterator from
046     * the specified node's childNodes.
047     *
048     * @param node Node, whose child nodes are wrapped by this class. Must not be null
049     * @throws NullPointerException if node is null
050     */
051    public NodeListIterator(final Node node) {
052        Objects.requireNonNull(node, "node");
053        this.nodeList = node.getChildNodes();
054    }
055
056    /**
057     * Constructor, that creates a new NodeListIterator from the specified
058     * {@code org.w3c.NodeList}
059     *
060     * @param nodeList node list, which is wrapped by this class. Must not be null
061     * @throws NullPointerException if nodeList is null
062     */
063    public NodeListIterator(final NodeList nodeList) {
064        this.nodeList = Objects.requireNonNull(nodeList, "nodeList");
065    }
066
067    @Override
068    public boolean hasNext() {
069        return nodeList != null && index < nodeList.getLength();
070    }
071
072    @Override
073    public Node next() {
074        if (nodeList != null && index < nodeList.getLength()) {
075            return nodeList.item(index++);
076        }
077        throw new NoSuchElementException("underlying nodeList has no more elements");
078    }
079
080    /**
081     * Always throws {@link UnsupportedOperationException}.
082     *
083     * @throws UnsupportedOperationException Always thrown.
084     */
085    @Override
086    public void remove() {
087        throw new UnsupportedOperationException("remove() method not supported for a NodeListIterator.");
088    }
089}