/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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: DTMChildIterNodeList.java 468653 2006-10-28 07:07:05Z minchau $
 */
package org.apache.xml.dtm.ref;

import org.apache.xml.dtm.DTM;
import org.w3c.dom.Node;

DTMNodeList 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:

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?) 
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. 

State: In progress!!
/**
 * <code>DTMNodeList</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 DTMChildIterNodeList extends DTMNodeListBase {
    private int m_firstChild;
    private DTM m_parentDTM;

    //================================================================
    // Methods unique to this class
    private DTMChildIterNodeList() {
    }

    
Public constructor: Create a NodeList to support
DTMNodeProxy.getChildren().
Unfortunately AxisIterators and DTMIterators don't share an API,
so I can't use the existing Axis.CHILD iterator. Rather than
create Yet Another Class, let's set up a special case of this
one.
Params:
parentDTM – The DTM containing this node
parentHandle – DTM node-handle integer/**
     * Public constructor: Create a NodeList to support
     * DTMNodeProxy.getChildren().
     *
     * Unfortunately AxisIterators and DTMIterators don't share an API,
     * so I can't use the existing Axis.CHILD iterator. Rather than
     * create Yet Another Class, let's set up a special case of this
     * one.
     *
     * @param parentDTM The DTM containing this node
     * @param parentHandle DTM node-handle integer
     *
     */
    public DTMChildIterNodeList(DTM parentDTM,int parentHandle) {
        m_parentDTM=parentDTM;
        m_firstChild=parentDTM.getFirstChild(parentHandle);
    }


    //================================================================
    // org.w3c.dom.NodeList API follows

    
Returns the indexth item in the collection. If 
index is greater than or equal to the number of nodes in 
the list, this returns null.
Params:
index – Index into the collection.
Returns:
The node at the indexth position in the 
  NodeList, or null if that is not a valid 
  index./**
     * 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) {
        int handle=m_firstChild;
        while(--index>=0 && handle!=DTM.NULL) {
            handle=m_parentDTM.getNextSibling(handle);
        }
        if (handle == DTM.NULL) {
            return null;
        }
        return m_parentDTM.getNode(handle);
    }

    
The number of nodes in the list. The range of valid child node indices 
is 0 to length-1 inclusive. 
/**
     * 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() {
        int count=0;
        for (int handle=m_firstChild;
             handle!=DTM.NULL;
             handle=m_parentDTM.getNextSibling(handle)) {
            ++count;
        }
        return count;
    }
}