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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: TemplateDOM.java,v 1.2 2005/01/26 08:29:24 jkjome Exp $
 */

package org.enhydra.xml.lazydom;

import org.enhydra.xml.dom.SimpleDOMTraversal;
import org.w3c.dom.Node;

//FIXME: need to add support for defaultAttrs and elementDefinitons

/**
 * Class used to contain hold a Template DOM that is shared by all instance
 * of the document.  This assign node ids to all nodes in the template,
 * mark them as template nodes and makes them read-only.
 */
public final class TemplateDOM {
    /** The template document, marked readonly */
    private LazyDocument fTemplateDocument;

    /** The maximum node id in the document */
    private int fMaxNodeId = LazyNode.NULL_NODE_ID;

    /** Table, indexed by node id, of nodes in the template doc */
    private LazyNode[] fTemplateNodes;

    /**
     * Constructor.
     */
    public TemplateDOM(LazyDocument templateDocument) {
        fTemplateDocument = templateDocument;
        // Only assigned ids if they don't already exist.
        if (fTemplateDocument.getNodeId() == LazyNode.NULL_NODE_ID) {
            assignNodeIds();
        } else {
            findMaxNodeId();
        }
        initNodeTable();
        templateDocument.setReadOnly(true, true);
    }

    /**
     * Assign node ids to all nodes.
     */
    private void assignNodeIds() {
        fMaxNodeId = LazyNode.DOCUMENT_NODE_ID;
        SimpleDOMTraversal traverser
            = new SimpleDOMTraversal(new SimpleDOMTraversal.Handler() {
                    public void handleNode(Node node) {
                        ((LazyNode)node).makeTemplateNode(fMaxNodeId++);
                    }
                });
        traverser.traverse(fTemplateDocument);
    }
    
    /**
     * Find the maximum node id; used when ids are already assigned
     */
    private void findMaxNodeId() {
        SimpleDOMTraversal traverser
            = new SimpleDOMTraversal(new SimpleDOMTraversal.Handler() {
                    public void handleNode(Node node) {
                        int nodeId = ((LazyNode)node).getNodeId();
                        if (nodeId > fMaxNodeId) {
                            fMaxNodeId = nodeId;
                        }
                    }
                });
        traverser.traverse(fTemplateDocument);
    }
    
    /**
     * Initialize the node table.
     */
    private void initNodeTable() {
        fTemplateNodes = new LazyNode[fMaxNodeId+1];

        SimpleDOMTraversal traverser
            = new SimpleDOMTraversal(new SimpleDOMTraversal.Handler() {
                    public void handleNode(Node node) {
                        LazyNode lazyNode = (LazyNode)node;
                        fTemplateNodes[lazyNode.getNodeId()] = lazyNode;
                    }
                });
        traverser.traverse(fTemplateDocument);
    }

    /**
     * Get the maximum node id.
     */
    public final int getMaxNodeId() {
        return fMaxNodeId;
    }

    /**
     * Get a node, given an id.
     * @param nodeId A valid node id for this document, or NULL_NODE_ID.
     * @return The template node, or null if NULL_NODE_ID was specified.
     */
    public final LazyNode getNode(int nodeId) {
        if (nodeId == LazyNode.NULL_NODE_ID) {
            return null;
        } else {
            return fTemplateNodes[nodeId];
        }
    }
}