/*

 * Copyright 2013 The Apache Software Foundation.

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package org.apache.commons.collections4.iterators;

import java.util.Iterator;

import java.util.NoSuchElementException;

import org.w3c.dom.Node;

import org.w3c.dom.NodeList;

/**

 * An {@link Iterator} over a {@link NodeList}.

 * <p>

 * This iterator does not support {@link #remove()} as a {@link NodeList} does not support

 * removal of items.

 *

 * @since 4.0

 * @see NodeList

 */

public class NodeListIterator implements Iterator<Node> {

    /** the original NodeList instance */

    private final NodeList nodeList;

    /** The current iterator index */

    private int index = 0;

    /**

     * Convenience constructor, which creates a new NodeListIterator from

     * the specified node's childNodes.

     *

     * @param node Node, who's child nodes are wrapped by this class. Must not be null

     * @throws NullPointerException if node is null

     */

    public NodeListIterator(final Node node) {

        if (node == null) {

            throw new NullPointerException("Node must not be null.");

        }

        this.nodeList = node.getChildNodes();

    }

    /**

     * Constructor, that creates a new NodeListIterator from the specified

     * <code>org.w3c.NodeList</code>

     *

     * @param nodeList node list, which is wrapped by this class. Must not be null

     * @throws NullPointerException if nodeList is null

     */

    public NodeListIterator(final NodeList nodeList) {

        if (nodeList == null) {

            throw new NullPointerException("NodeList must not be null.");

        }

        this.nodeList = nodeList;

    }

    @Override

    public boolean hasNext() {

        return nodeList != null && index < nodeList.getLength();

    }

    @Override

    public Node next() {

        if (nodeList != null && index < nodeList.getLength()) {

            return nodeList.item(index++);

        }

        throw new NoSuchElementException("underlying nodeList has no more elements");

    }

    /**

     * Throws {@link UnsupportedOperationException}.

     *

     * @throws UnsupportedOperationException always

     */

    @Override

    public void remove() {

        throw new UnsupportedOperationException("remove() method not supported for a NodeListIterator.");

    }

}