001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-present, by David Gilbert and Contributors.
006 *
007 * Project Info:  http://www.jfree.org/jfreechart/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it
010 * under the terms of the GNU Lesser General Public License as published by
011 * the Free Software Foundation; either version 2.1 of the License, or
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
022 * USA.
023 *
024 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
025 * Other names may be trademarks of their respective owners.]
026 *
027 * ----------------
028 * RootHandler.java
029 * ----------------
030 * (C) Copyright 2003-present, by David Gilbert and Contributors.
031 *
032 * Original Author:  David Gilbert;
033 * Contributor(s):   -;
034 *
035 */
036
037package org.jfree.data.xml;
038
039import java.util.Stack;
040
041import org.xml.sax.SAXException;
042import org.xml.sax.helpers.DefaultHandler;
043
044/**
045 * A SAX handler that delegates work to sub-handlers.
046 */
047public class RootHandler extends DefaultHandler implements DatasetTags {
048
049    /** The sub-handlers. */
050    private Stack subHandlers;
051
052    /**
053     * Creates a new handler.
054     */
055    public RootHandler() {
056        this.subHandlers = new Stack();
057    }
058
059    /**
060     * Returns the stack of sub handlers.
061     *
062     * @return The sub-handler stack.
063     */
064    public Stack getSubHandlers() {
065        return this.subHandlers;
066    }
067
068    /**
069     * Receives some (or all) of the text in the current element.
070     *
071     * @param ch  character buffer.
072     * @param start  the start index.
073     * @param length  the length of the valid character data.
074     *
075     * @throws SAXException for errors.
076     */
077    @Override
078    public void characters(char[] ch, int start, int length)
079        throws SAXException {
080        DefaultHandler handler = getCurrentHandler();
081        if (handler != this) {
082            handler.characters(ch, start, length);
083        }
084    }
085
086    /**
087     * Returns the handler at the top of the stack.
088     *
089     * @return The handler.
090     */
091    public DefaultHandler getCurrentHandler() {
092        DefaultHandler result = this;
093        if (this.subHandlers != null) {
094            if (this.subHandlers.size() > 0) {
095                Object top = this.subHandlers.peek();
096                if (top != null) {
097                    result = (DefaultHandler) top;
098                }
099            }
100        }
101        return result;
102    }
103
104    /**
105     * Pushes a sub-handler onto the stack.
106     *
107     * @param subhandler  the sub-handler.
108     */
109    public void pushSubHandler(DefaultHandler subhandler) {
110        this.subHandlers.push(subhandler);
111    }
112
113    /**
114     * Pops a sub-handler from the stack.
115     *
116     * @return The sub-handler.
117     */
118    public DefaultHandler popSubHandler() {
119        return (DefaultHandler) this.subHandlers.pop();
120    }
121
122}