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/*
 * Enhydra Java Application Server Project
 * 
 * The contents of this file are subject to the Enhydra Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License on
 * the Enhydra web site ( http://www.enhydra.org/ ).
 * 
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See 
 * the License for the specific terms governing rights and limitations
 * under the License.
 * 
 * The Initial Developer of the Enhydra Application Server is Lutris
 * Technologies, Inc. The Enhydra Application Server and portions created
 * by Lutris Technologies, Inc. are Copyright Lutris Technologies, Inc.
 * All Rights Reserved.
 * 
 * Contributor(s):
 * 
 * $Id: SimpleDOMTraversal.java,v 1.2 2005/01/26 08:29:24 jkjome Exp $
 */

package org.enhydra.xml.dom;

import org.enhydra.xml.lazydom.LazyDOMSimpleTraversal;
import org.w3c.dom.Document;
import org.w3c.dom.DocumentType;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;

//FIXME: Makes so it doesn't expand, but LazyDOM counts on this.

/**
 * Simple DOM traverser that calls a handler for every node in the DOM tree.
 */
public class SimpleDOMTraversal {
    /**
     * Interface for node callback object.
     */
    public interface Handler {
        /**
         * Handler called for each Node.
         */
        public void handleNode(Node node);
    }

    /** Handler object for the traversal */
    protected Handler fHandler;

    /**
     * Constructor.
     * @param handler The object that will be called to handle each
     *  node.
     */
    public SimpleDOMTraversal(SimpleDOMTraversal.Handler handler) {
        fHandler = handler;
    }

    /**
     * Traverse a DOM tree or subtree.
     *
     * @param root The root of the DOM tree or subtree that is to
     *  be traversed.
     */
    public void traverse(Node root) {
        processNode(root);
    }

    /**
     * Process the children of a node.  
     */
    protected void processChildren(Node node) {
        //FIXME: Xerces sometimes has DocumentType objects as children (bug?)
        for (Node child = node.getFirstChild(); child != null;
             child = child.getNextSibling()) {
            if (!(child instanceof DocumentType)) {
                processNode(child);
            }
        }
    }
    
    /**
     * Process the attributes of an element.
     */
    protected void processAttributes(Node node) {
        NamedNodeMap attrMap = node.getAttributes();
        int len = attrMap.getLength();
        for (int i = 0; i < len; i++) {
            processNode(attrMap.item(i));
        }
    }

    /**
     * Process a DocumentType attribute of a Document node, if it exists.
     */
    public void processDocumentType(Document document) {
        DocumentType docType = document.getDoctype();
        if (docType != null) {
            processNode(docType);
        }
    }

    /**
     * Process the contents of a DocumentType node,
     */
    protected void processDocumentTypeContents(DocumentType documentType) {
        processNamedNodeMap(documentType.getEntities());
        processNamedNodeMap(documentType.getNotations());
    }

    /**
     * Process contents of a NamedNodeMap.
     */
    private void processNamedNodeMap(NamedNodeMap nodeMap) {
        if (nodeMap != null) {
            int len = nodeMap.getLength();
            for (int i = 0; i < len; i++) {
                processNode(nodeMap.item(i));
            }
        }
    }

    /**
     * Processing based on node type.  All nodes go through here.
     */
    protected void processNode(Node node) {
        fHandler.handleNode(node);
        if (node instanceof Document) {
            processDocumentType((Document)node);
        } else if (node instanceof DocumentType) {
            DocumentType docType = (DocumentType)node;
            processNamedNodeMap(docType.getEntities());
            processNamedNodeMap(docType.getNotations());
        } else if (node instanceof Element) {
            processAttributes(node);
        }

        processChildren(node);
    }

    /**
     * Factory method to create a traverser based on the type of
     * a document.
     */
    public static SimpleDOMTraversal getTraverser(SimpleDOMTraversal.Handler handler,
                                                  Node node) {
        /* 
         * Find the document to determine type.  The LazyDOM traverser is only
         * used on instance documents.  If a template DOM node is specified,
         * the template LazyDocument is traverse as any other done.
         */
        if (DOMOps.isLazyDOMInstance(DOMOps.getDocument(node))) {
            return new LazyDOMSimpleTraversal(handler);
        } else {
            return new SimpleDOMTraversal(handler);
        }
    }
}