/*-- 

 Copyright (C) 2001 Brett McLaughlin.
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 
 1. Redistributions of source code must retain the above copyright
    notice, this list of conditions, and the following disclaimer.
 
 2. Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions, and the disclaimer that follows 
    these conditions in the documentation and/or other materials 
    provided with the distribution.

 3. The name "Java and XML" must not be used to endorse or promote products
    derived from this software without prior written permission.  For
    written permission, please contact brett@newInstance.com.
 
 In addition, we request (but do not require) that you include in the 
 end-user documentation provided with the redistribution and/or in the 
 software itself an acknowledgement equivalent to the following:
     "This product includes software developed for the
      'Java and XML' book, by Brett McLaughlin (O'Reilly & Associates)."

 THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED.  IN NO EVENT SHALL THE JDOM AUTHORS OR THE PROJECT
 CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 SUCH DAMAGE.

 */
package javaxml2;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.XMLFilterImpl;

/**
 * <p><code>NamespaceFilter</code> will take a namespace URI and replace
 *   all occurences of that URI with a newer, supplied URI. This effectively
 *   allows on-the-fly namespace changes.</p>
 */
public class NamespaceFilter extends XMLFilterImpl {
    
    /** The old URI, to replace */
    private String oldURI;
    
    /** The new URI, to replace the old URI with */
    private String newURI;

    /**
     * <p>This will take the <code>XMLReader</code> to use as a parent,
     *   as well as the URI to replace, and the URI to replace it with.</p>
     *
     * @param reader <code>XMLReader</code> to be this filter's parent.
     * @param oldURI URI to replace occurrences of.
     * @param newURI URI to replace with.
     */
    public NamespaceFilter(XMLReader reader, 
                           String oldURI, String newURI) {
        super(reader);
        this.oldURI = oldURI;
        this.newURI = newURI;
    }
    
    public void startPrefixMapping(String prefix, String uri)
        throws SAXException {
            
        // Change URI, if needed
        if (uri.equals(oldURI)) {
            super.startPrefixMapping(prefix, newURI);
        } else {
            super.startPrefixMapping(prefix, uri);
        }        
    }
    
    public void startElement(String uri, String localName,
                             String qName, Attributes attributes)
        throws SAXException {
            
        // Change URI, if needed
        if (uri.equals(oldURI)) {
            super.startElement(newURI, localName, qName, attributes);
        } else {            
            super.startElement(uri, localName, qName, attributes);
        }       
    }
    
    public void endElement(String uri, String localName, String qName)
        throws SAXException {
            
        // Change URI, if needed
        if (uri.equals(oldURI)) {
            super.endElement(newURI, localName, qName);
        } else {            
            super.endElement(uri, localName, qName);
        }
    }
}