/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * Copyright 1999-2004 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.

 */

/*

 * $Id: DTMAxisIterNodeList.java,v 1.2.4.1 2005/09/15 08:14:59 suresh_emailid Exp $

 */

package com.sun.org.apache.xml.internal.dtm.ref;

import com.sun.org.apache.xml.internal.dtm.DTM;

import com.sun.org.apache.xml.internal.dtm.DTMAxisIterator;

import com.sun.org.apache.xml.internal.utils.IntVector;

import org.w3c.dom.Node;

/**

 * <code>DTMAxisNodeList</code> gives us an implementation of the DOM's

 * NodeList interface wrapped around a DTM Iterator. The author

 * considers this something of an abominations, since NodeList was not

 * intended to be a general purpose "list of nodes" API and is

 * generally considered by the DOM WG to have be a mistake... but I'm

 * told that some of the XPath/XSLT folks say they must have this

 * solution.

 *

 * Please note that this is not necessarily equivlaent to a DOM

 * NodeList operating over the same document. In particular:

 * <ul>

 *

 * <li>If there are several Text nodes in logical succession (ie,

 * across CDATASection and EntityReference boundaries), we will return

 * only the first; the caller is responsible for stepping through

 * them.

 * (%REVIEW% Provide a convenience routine here to assist, pending

 * proposed DOM Level 3 getAdjacentText() operation?) </li>

 *

 * <li>Since the whole XPath/XSLT architecture assumes that the source

 * document is not altered while we're working with it, we do not

 * promise to implement the DOM NodeList's "live view" response to

 * document mutation. </li>

 *

 * </ul>

 *

 * <p>State: In progress!!</p>

 * */

public class DTMAxisIterNodeList extends DTMNodeListBase {

    private DTM m_dtm;

    private DTMAxisIterator m_iter;

    private IntVector m_cachedNodes;

    private int m_last = -1;

    //================================================================

    // Methods unique to this class

    private DTMAxisIterNodeList() {

    }

    /**

     * Public constructor: Wrap a DTMNodeList around an existing

     * and preconfigured DTMAxisIterator

     */

    public DTMAxisIterNodeList(DTM dtm, DTMAxisIterator dtmAxisIterator) {

        if (dtmAxisIterator == null) {

            m_last = 0;

        } else {

            m_cachedNodes = new IntVector();

            m_dtm = dtm;

        }

        m_iter = dtmAxisIterator;

    }

    /**

     * Access the wrapped DTMIterator. I'm not sure whether anyone will

     * need this or not, but let's write it and think about it.

     *

     */

    public DTMAxisIterator getDTMAxisIterator() {

        return m_iter;

    }

    //================================================================

    // org.w3c.dom.NodeList API follows

    /**

     * Returns the <code>index</code>th item in the collection. If

     * <code>index</code> is greater than or equal to the number of nodes in

     * the list, this returns <code>null</code>.

     * @param index Index into the collection.

     * @return The node at the <code>index</code>th position in the

     *   <code>NodeList</code>, or <code>null</code> if that is not a valid

     *   index.

     */

    public Node item(int index) {

        if (m_iter != null) {

            int count = m_cachedNodes.size();

            if (count > index) {

                node = m_cachedNodes.elementAt(index);

                return m_dtm.getNode(node);

            } else if (m_last == -1) {

                    m_cachedNodes.addElement(node);

                    count++;

                }

                if (node == DTMAxisIterator.END) {

                    m_last = count;

                } else {

                    return m_dtm.getNode(node);

                }

            }

        }

        return null;

    }

    /**

     * The number of nodes in the list. The range of valid child node indices

     * is 0 to <code>length-1</code> inclusive.

     */

    public int getLength() {

        if (m_last == -1) {

            int node;

            while ((node = m_iter.next()) != DTMAxisIterator.END) {

                m_cachedNodes.addElement(node);

            }

            m_last = m_cachedNodes.size();

        }

        return m_last;

    }

}