/*

  * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/DefaultNavigator.java,v 1.19 2006/02/05 21:47:41 elharo Exp $

  * $Revision: 1.19 $

  * $Date: 2006/02/05 21:47:41 $

  *

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

  *

  * 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: DefaultNavigator.java,v 1.19 2006/02/05 21:47:41 elharo Exp $

  */

 package org.jaxen;

 import java.util.Iterator;

 import org.jaxen.pattern.Pattern;

 import org.jaxen.util.AncestorAxisIterator;

 import org.jaxen.util.AncestorOrSelfAxisIterator;

 import org.jaxen.util.DescendantAxisIterator;

 import org.jaxen.util.DescendantOrSelfAxisIterator;

 import org.jaxen.util.FollowingAxisIterator;

 import org.jaxen.util.FollowingSiblingAxisIterator;

 import org.jaxen.util.PrecedingAxisIterator;

 import org.jaxen.util.PrecedingSiblingAxisIterator;

 import org.jaxen.util.SelfAxisIterator;

 /** Default implementation of {@link Navigator}.

  *

  *  <p>

  *  This implementation is an abstract class, since

  *  some required operations cannot be implemented without

  *  additional knowledge of the object model.

  *  </p>

  *

  *  <p>

  *  When possible, default method implementations build

  *  upon each other, to reduce the number of methods required

  *  to be implemented for each object model.  All methods,

  *  of course, may be overridden, to provide more-efficient

  *  implementations.

  *  </p>

  *

  *  @author bob mcwhirter (bob@werken.com)

  *  @author Erwin Bolwidt (ejb@klomp.org)

  */

 public abstract class DefaultNavigator implements Navigator

 {

     /** Throws <code>UnsupportedAxisException</code>

      * 

      * @param contextNode

      * @return never returns

      * @throws UnsupportedAxisException always

      */

     public Iterator getChildAxisIterator(Object contextNode) throws UnsupportedAxisException

     {

         throw new UnsupportedAxisException("child");

     }

     /* (non-Javadoc)

      * @see org.jaxen.Navigator#getDescendantAxisIterator(java.lang.Object)

      */

     public Iterator getDescendantAxisIterator(Object contextNode) throws UnsupportedAxisException

     {

         return new DescendantAxisIterator( contextNode,

                                            this );

     }

     /** Throws <code>UnsupportedAxisException</code>

      * 

      * @param  contextNode

      * @return never returns

      * @throws UnsupportedAxisException

      */

     public Iterator getParentAxisIterator(Object contextNode) throws UnsupportedAxisException

     {

         throw new UnsupportedAxisException("parent");

     }

     public Iterator getAncestorAxisIterator(Object contextNode) throws UnsupportedAxisException

     {

         return new AncestorAxisIterator( contextNode,

                                          this );

     }

     public Iterator getFollowingSiblingAxisIterator(Object contextNode) throws UnsupportedAxisException

     {

         return new FollowingSiblingAxisIterator( contextNode,

                                                  this );

     }

     public Iterator getPrecedingSiblingAxisIterator(Object contextNode) throws UnsupportedAxisException

     {

         return new PrecedingSiblingAxisIterator( contextNode,

                                                  this );

     }

     public Iterator getFollowingAxisIterator(Object contextNode) throws UnsupportedAxisException

     {

         return new FollowingAxisIterator( contextNode,

                                           this );

         // throw new UnsupportedAxisException("following");

     }

     public Iterator getPrecedingAxisIterator(Object contextNode) throws UnsupportedAxisException

     {

         return new PrecedingAxisIterator( contextNode,

                                          this );

         // throw new UnsupportedAxisException("preceding");

     }

     /** Throws <code>UnsupportedAxisException</code>. Subclasses that 

      * support the attribute axis must override this method.

      * 

      * @param contextNode

      * @return never returns

      * @throws UnsupportedAxisException

      */

     public Iterator getAttributeAxisIterator(Object contextNode) throws UnsupportedAxisException

     {

         throw new UnsupportedAxisException("attribute");

     }

     /** Throws <code>UnsupportedAxisException</code>. Subclasses that 

      * support the namespace axis must override this method.

      * 

      * @param contextNode

      * @return never returns

      * @throws UnsupportedAxisException

      */

     public Iterator getNamespaceAxisIterator(Object contextNode) throws UnsupportedAxisException

     {

         throw new UnsupportedAxisException("namespace");

     }

     public Iterator getSelfAxisIterator(Object contextNode) throws UnsupportedAxisException

     {

         return new SelfAxisIterator( contextNode );

     }

     public Iterator getDescendantOrSelfAxisIterator(Object contextNode) throws UnsupportedAxisException

     {

         return new DescendantOrSelfAxisIterator( contextNode,

                                                  this );

     }

     public Iterator getAncestorOrSelfAxisIterator(Object contextNode) throws UnsupportedAxisException

     {

         return new AncestorOrSelfAxisIterator( contextNode,

                                                this );

     }

     public Object getDocumentNode(Object contextNode)

     {

         return null;

     }

     public String translateNamespacePrefixToUri(String prefix, Object element)

     {

         return null;

     }

     public String getProcessingInstructionTarget(Object obj)

     {

         return null;

     }

     public String getProcessingInstructionData(Object obj)

     {

         return null;

     }

     public short getNodeType(Object node)

     {

         if ( isElement(node) ) 

         {

             return Pattern.ELEMENT_NODE;

         }

         else if ( isAttribute(node) ) 

         {

             return Pattern.ATTRIBUTE_NODE;

         }

         else if ( isText(node) ) 

         {

             return Pattern.TEXT_NODE;

         }

         else if ( isComment(node) ) 

         {

             return Pattern.COMMENT_NODE;

         }

         else if ( isDocument(node) ) 

         {

             return Pattern.DOCUMENT_NODE;

         }

         else if ( isProcessingInstruction(node) ) 

         {

             return Pattern.PROCESSING_INSTRUCTION_NODE;

         }

         else if ( isNamespace(node) ) 

         {

             return Pattern.NAMESPACE_NODE;

         }

         else {

             return Pattern.UNKNOWN_NODE;

         }

     }

     /**

      * Default inefficient implementation. Subclasses 

      * should override this method.

      *

      * @param contextNode   the node whose parent to return

      * @return the parent node

      * @throws UnsupportedAxisException if the parent axis is not supported

      */

     public Object getParentNode(Object contextNode) throws UnsupportedAxisException

     {

         Iterator iter = getParentAxisIterator( contextNode );

         if ( iter != null && iter.hasNext() )

         {

             return iter.next();

         }

         return null;

     }

     /**

      *  Default implementation that always returns null. Override in subclass

      *  if the subclass can load documents. 

      *

      * @param url the URL of the document to load

      *

      * @return null

      * @throws FunctionCallException if an error occurs while loading the

      *    URL; e.g. an I/O error or the document is malformed

      */

     public Object getDocument(String url) throws FunctionCallException

     {

         return null;

     }

     /**

      *  Default implementation that cannot find elements. Override in subclass

      *  if subclass does know about attribute types.

      *

      *  @param contextNode   a node from the document in which to look for the

      *                       id

      *  @param elementId   id to look for

      *

      *  @return   null

      */

     public Object getElementById(Object contextNode, String elementId)

     {

         return null;

     }

 }