/*

  * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/SimpleNamespaceContext.java,v 1.18 2006/06/03 20:19:26 elharo Exp $

  * $Revision: 1.18 $

  * $Date: 2006/06/03 20:19:26 $

  *

  * ====================================================================

  *

  * Copyright 2000-2002 bob mcwhirter & James Strachan.

  * All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions are

  * met:

  * 

  *   * Redistributions of source code must retain the above copyright

  *     notice, this list of conditions and the following disclaimer.

  * 

  *   * Redistributions in binary form must reproduce the above copyright

  *     notice, this list of conditions and the following disclaimer in the

  *     documentation and/or other materials provided with the distribution.

  * 

  *   * Neither the name of the Jaxen Project nor the names of its

  *     contributors may be used to endorse or promote products derived 

  *     from this software without specific prior written permission.

  * 

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

  * IS" AND ANY EXPRESS 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 COPYRIGHT OWNER

  * OR 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.

  *

  * ====================================================================

  * This software consists of voluntary contributions made by many 

  * individuals on behalf of the Jaxen Project and was originally 

  * created by bob mcwhirter <bob@werken.com> and 

  * James Strachan <jstrachan@apache.org>.  For more information on the 

  * Jaxen Project, please see <http://www.jaxen.org/>.

  * 

  * $Id: SimpleNamespaceContext.java,v 1.18 2006/06/03 20:19:26 elharo Exp $

  */

 package org.jaxen;

 import java.io.Serializable;

 import java.util.HashMap;

 import java.util.Iterator;

 import java.util.Map;

 /**

  *  Provides mappings from namespace prefix to namespace URI to the XPath

  *  engine.

  */

 public class SimpleNamespaceContext implements NamespaceContext, Serializable

 {

     /**

      * 

      */

     private static final long serialVersionUID = -808928409643497762L;

     // XXX should this prebind the xml prefix?

     private Map namespaces;

     /**

      * Creates a new empty namespace context.

      */

     public SimpleNamespaceContext()

     {

         this.namespaces = new HashMap();

     }

     /**

      * Creates a new namespace context pre-populated with the specified bindings. 

      * 

      * @param namespaces the initial namespace bindings in scope. The keys in this

      *     must be strings containing the prefixes and the values are strings

      *     containing the namespace URIs.

      *     

      * @throws NullPointerException if the argument is null   

      * @throws ClassCastException if any keys or values in the map are not strings   

      */

     public SimpleNamespaceContext(Map namespaces)

     {

         Iterator entries = namespaces.entrySet().iterator();

         while (entries.hasNext()) {

             Map.Entry entry = (Map.Entry) entries.next();

             if (! (entry.getKey() instanceof String)

               || ! (entry.getValue() instanceof String)) {

                 throw new ClassCastException("Non-string namespace binding");

             }

         }

         this.namespaces = new HashMap(namespaces);

     }

     /**

      *  Adds all the namespace declarations that are in scope on the given

      *  element. In the case of an XSLT stylesheet, this would be the element

      *  that has the XPath expression in one of its attributes; e.g.

      *  <code>&lt;xsl:if test="condition/xpath/expression"&gt;</code>.

      *

      *  @param nav  the navigator for use in conjunction with

      *              <code>element</code>

      *  @param element the element to copy the namespaces from

      *  @throws UnsupportedAxisException if the navigator does not support the 

      *     namespace axis

      */

     public void addElementNamespaces( Navigator nav, Object element )

         throws UnsupportedAxisException

     {

         Iterator namespaceAxis = nav.getNamespaceAxisIterator( element );

         while ( namespaceAxis.hasNext() ) {

             Object namespace = namespaceAxis.next();

             String prefix = nav.getNamespacePrefix( namespace );

             String uri = nav.getNamespaceStringValue( namespace );

             if ( translateNamespacePrefixToUri(prefix) == null ) {

                 addNamespace( prefix, uri );

             }

         }

     }    

     // ???? What if prefix or URI is null, or both?

     /**

      * Binds a prefix to a URI in this context.

      * 

      * @param prefix the namespace prefix

      * @param URI    the namespace URI

      */

     public void addNamespace(String prefix, String URI)

     {

         this.namespaces.put( prefix, URI );

     }

     public String translateNamespacePrefixToUri(String prefix)

     {

         if ( this.namespaces.containsKey( prefix ) )

         {

             return (String) this.namespaces.get( prefix );

         }

         return null;

     }

 }