/*

  * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/dom/NamespaceNode.java,v 1.25 2006/07/03 11:14:05 elharo Exp $

  * $Revision: 1.25 $

  * $Date: 2006/07/03 11:14:05 $

  *

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

  *

  * 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: NamespaceNode.java,v 1.25 2006/07/03 11:14:05 elharo Exp $

  */

 ////////////////////////////////////////////////////////////////////

 // Inner class for a Namespace node.

 ////////////////////////////////////////////////////////////////////

 package org.jaxen.dom;

 import java.lang.reflect.InvocationTargetException;

 import java.lang.reflect.Method;

 import java.util.HashMap;

 import org.jaxen.pattern.Pattern;

 import org.w3c.dom.DOMException;

 import org.w3c.dom.Document;

 import org.w3c.dom.NamedNodeMap;

 import org.w3c.dom.Node;

 import org.w3c.dom.NodeList;

 import org.w3c.dom.UserDataHandler;

 /**

  * Extension DOM2/DOM3 node type for a namespace node.

  *

  * <p>This class implements the DOM2 and DOM3 {@link Node} interface

  * to allow namespace nodes to be included in the result

  * set of an XPath selectNodes operation, even though DOM does

  * not model namespaces in scope as separate nodes.</p>

  *

  * <p>

  * While all of the DOM2 methods are implemented with reasonable

  * defaults, there will be some unexpected surprises, so users are

  * advised to test for NamespaceNodes and filter them out from the

  * result sets as early as possible.

   * </p>

  *

  * <ol>

  *

  * <li>The {@link #getNodeType} method returns {@link #NAMESPACE_NODE},

  * which is not one of the usual DOM2 node types.  Generic code may

  * fall unexpectedly out of switch statements, for example.</li>

  *

  * <li>The {@link #getOwnerDocument} method returns the owner document

  * of the parent node, but that owner document will know nothing about

  * the namespace node.</p>

  *

  * <li>The {@link #isSupported} method always returns false.</li>

  *

  * <li> The DOM3 methods sometimes throw UnsupportedOperationException.

  *      They're here only to allow this class to be compiled with Java 1.5.

  *       Do not call or rely on them.</li>

  * </ol>

  *

  * <p>All attempts to modify a <code>NamespaceNode</code> will fail with a {@link

  * DOMException} ({@link

  * DOMException#NO_MODIFICATION_ALLOWED_ERR}).</p>

  *

  * @author David Megginson

  * @author Elliotte Rusty Harold

  * @see DocumentNavigator

  */

 public class NamespaceNode implements Node

 {

     /**

      * Constant: this is a NamespaceNode.

      *

      * @see #getNodeType

      */

     public final static short NAMESPACE_NODE = Pattern.NAMESPACE_NODE;

     // FIXME "Note: Numeric codes up to 200 are reserved to W3C for possible future use."

     // We should be using higher codes. Here we're using 13, the same as DOM 3's type for XPathNamespace.

     // However, that's only a note not a recommendation.

     /**

      * Create a new NamespaceNode.

      *

      * @param parent the DOM node to which the namespace is attached

      * @param name the namespace prefix

      * @param value the namespace URI

      */

     public NamespaceNode (Node parent, String name, String value)

     {

         this.parent = parent;

         this.name = name;

         this.value = value;

     }

     /**

      * Constructor.

      *

      * @param parent the DOM node to which the namespace is attached

      * @param attribute the DOM attribute object containing the

      *        namespace declaration

      */

     NamespaceNode (Node parent, Node attribute)

     {

         String attributeName = attribute.getNodeName();

         if (attributeName.equals("xmlns")) {

             this.name = "";

         }

         else if (attributeName.startsWith("xmlns:")) {

             this.name = attributeName.substring(6); // the part after "xmlns:"

         }

         else { // workaround for Crimson bug; Crimson incorrectly reports the prefix as the node name

             this.name = attributeName;

         }

         this.parent = parent;

         this.value = attribute.getNodeValue();

     }

     ////////////////////////////////////////////////////////////////////

     // Implementation of org.w3c.dom.Node.

     ////////////////////////////////////////////////////////////////////

     /**

      * Get the namespace prefix.

      *

      * @return the namespace prefix, or "" for the default namespace

      */

     public String getNodeName ()

     {

         return name;

     }

     /**

      * Get the namespace URI.

      *

      * @return the namespace URI

      */

     public String getNodeValue ()

     {

         return value;

     }

     /**

      * Change the namespace URI (always fails).

      *

      * @param value the new URI

      * @throws DOMException always

      */

     public void setNodeValue (String value) throws DOMException

     {

         disallowModification();

     }

     /**

      * Get the node type.

      *

      * @return always {@link #NAMESPACE_NODE}.

      */

     public short getNodeType ()

     {

         return NAMESPACE_NODE;

     }

     /**

      * Get the parent node.

      *

      * <p>This method returns the element that was queried for Namespaces

      * in effect, <em>not</em> necessarily the actual element containing

      * the Namespace declaration.</p>

      *

      * @return the parent node (not null)

      */

     public Node getParentNode ()

     {

         return parent;

     }

     /**

      * Get the list of child nodes.

      *

      * @return an empty node list

      */

     public NodeList getChildNodes ()

     {

         return new EmptyNodeList();

     }

     /**

      * Get the first child node.

      *

      * @return null

      */

     public Node getFirstChild ()

     {

         return null;

     }

     /**

      * Get the last child node.

      *

      * @return null

      */

     public Node getLastChild ()

     {

         return null;

     }

     /**

      * Get the previous sibling node.

      *

      * @return null

      */

     public Node getPreviousSibling ()

     {

         return null;

     }

     /**

      * Get the next sibling node.

      *

      * @return null

      */

     public Node getNextSibling ()

     {

         return null;

     }

     /**

      * Get the attribute nodes.

      *

      * @return null

      */

     public NamedNodeMap getAttributes ()

     {

         return null;

     }

     /**

      * Get the owner document.

      *

      * @return the owner document <em>of the parent node</em>

      */

     public Document getOwnerDocument ()

     {

         if (parent == null) return null;

         return parent.getOwnerDocument();

     }

     /**

      * Insert a new child node (always fails).

      * 

      * @param newChild the node to add

      * @param refChild ignored

      * @return never

      * @throws DOMException always

      * @see Node#insertBefore

      */

     public Node insertBefore (Node newChild, Node refChild)

     throws DOMException

     {

         disallowModification();

         return null;

     }

     /**

      * Replace a child node (always fails).

      *

      * @param newChild the node to add

      * @param oldChild the child node to replace

      * @return never

      * @throws DOMException always

      * @see Node#replaceChild

      */

     public Node replaceChild (Node newChild, Node oldChild) throws DOMException

     {

         disallowModification();

         return null;

     }

     /**

      * Remove a child node (always fails).

      *

      * @param oldChild the child node to remove

      * @return never

      * @throws DOMException always

      * @see Node#removeChild

      */

     public Node removeChild(Node oldChild) throws DOMException

     {

         disallowModification();

         return null;

     }

     /**

      * Append a new child node (always fails).

      *

      * @param newChild the node to add

      * @return never

      * @throws DOMException always

      * @see Node#appendChild

      */

     public Node appendChild(Node newChild) throws DOMException

     {

         disallowModification();

         return null;

     }

     /**

      * Test for child nodes.

      *

      * @return false

      */

     public boolean hasChildNodes()

     {

         return false;

     }

     /**

      * Create a copy of this node.

      *

      * @param deep make a deep copy (no effect, since namespace nodes

      *        don't have children).

      * @return a new copy of this namespace node

      */

     public Node cloneNode (boolean deep)

     {

         return new NamespaceNode(parent, name, value);

     }

     /**

      * Normalize the text descendants of this node.

      *

      * <p>This method has no effect, since namespace nodes have no

      * descendants.</p>

      */

     public void normalize ()

     {

     // no op

     }

     /**

      * Test if a DOM2 feature is supported. (None are.)

      *

      * @param feature the feature name

      * @param version the feature version

      * @return false

      */

     public boolean isSupported(String feature, String version)

     {

         return false;

     }

     /**

      * Get the namespace URI of this node.

      *

      * <p>Namespace declarations are not themselves

      * Namespace-qualified.</p>

      *

      * @return null

      */

     public String getNamespaceURI()

     {

        return null;

     }

     /**

      * Get the namespace prefix of this node.

      *

      * <p>Namespace declarations are not themselves

      * namespace-qualified.</p>

      *

      * @return null

      * @see #getLocalName

      */

     public String getPrefix()

     {

         return null;

     }

     /**

      * Change the namespace prefix of this node (always fails).

      *

      * @param prefix the new prefix

      * @throws DOMException always thrown

      */

     public void setPrefix(String prefix)

     throws DOMException

     {

         disallowModification();

     }

     /**

      * Get the XPath name of the namespace node;; i.e. the

      * namespace prefix.

      *

      * @return the namespace prefix

      */

     public String getLocalName ()

     {

         return name;

     }

     /**

      * Test if this node has attributes.

      *

      * @return false

      */

     public boolean hasAttributes ()

     {

         return false;

     }

     /**

      * Throw a NO_MODIFICATION_ALLOWED_ERR DOMException.

      *

      * @throws DOMException always thrown

      */

     private void disallowModification () throws DOMException

     {

         throw new DOMException(DOMException.NO_MODIFICATION_ALLOWED_ERR,

                    "Namespace node may not be modified");

     }

     ////////////////////////////////////////////////////////////////////

     // Override default methods from java.lang.Object.

     ////////////////////////////////////////////////////////////////////

     /**

      * Generate a hash code for a namespace node.

      *

      * @return a hash code for this node

      */

     public int hashCode ()

     {

         return hashCode(parent) + hashCode(name) + hashCode(value);

     }

     /**

      * Test for equivalence with another object.

      *

      * <p>Two Namespace nodes are considered equivalent if their parents,

      * names, and values are equal.</p>

      *

      * @param o the object to test for equality

      * @return true if the object is equivalent to this node, false

      *         otherwise

      */

     public boolean equals (Object o)

     {

         if (o == this) return true;

         else if (o == null) return false;

         else if (o instanceof NamespaceNode) {

             NamespaceNode ns = (NamespaceNode)o;

             return (equals(parent, ns.getParentNode()) &&

                 equals(name, ns.getNodeName()) &&

                 equals(value, ns.getNodeValue()));

         } else {

             return false;

         }

     }

     /**

      * Helper method for generating a hash code.

      *

      * @param o the object for generating a hash code (possibly null)

      * @return the object's hash code, or 0 if the object is null

      * @see java.lang.Object#hashCode

      */

     private int hashCode (Object o)

     {

         return (o == null ? 0 : o.hashCode());

     }

     /**

      * Helper method for comparing two objects.

      *

      * @param a the first object to compare (possibly null)

      * @param b the second object to compare (possibly null)

      * @return true if the objects are equivalent or are both null

      * @see java.lang.Object#equals

      */

     private boolean equals (Object a, Object b)

     {

         return ((a == null && b == null) ||

           (a != null && a.equals(b)));

     }

     ////////////////////////////////////////////////////////////////////

     // Internal state.

     ////////////////////////////////////////////////////////////////////

     private Node parent;

     private String name;

     private String value;

     ////////////////////////////////////////////////////////////////////

     // Inner class: empty node list.

     ////////////////////////////////////////////////////////////////////

     /**

      * A node list with no members.

      *

      * <p>This class is necessary for the {@link Node#getChildNodes}

      * method, which must return an empty node list rather than

      * null when there are no children.</p>

      */

     private static class EmptyNodeList implements NodeList

     {

         /**

          * @see NodeList#getLength

          */

         public int getLength ()

         {

             return 0;

         }

         /**

          * @see NodeList#item

          */

         public Node item(int index)

         {

             return null;

         }

     }

     ////////////////////////////////////////////////////////////////////

     // DOM Level 3 methods

     ////////////////////////////////////////////////////////////////////

     /**

      * Return the base URI of the document containing this node. 

      * This only works in DOM 3.

      *

      * @return null

      */

     public String getBaseURI() {

         Class clazz = Node.class;

         try {

             Class[] args = new Class[0];

             Method getBaseURI = clazz.getMethod("getBaseURI", args);

             String base = (String) getBaseURI.invoke(this.getParentNode(), args);

             return base;

         }

         catch (Exception ex) {

             return null;

         }

     }

     /**

      * Compare relative position of this node to another nbode. (Always fails).

      * This method is included solely for compatibility with the superclass.

      * 

      * @param other the node to compare to

      *

      * @return never

      * @throws DOMException NOT_SUPPORTED_ERR

      */

     public short compareDocumentPosition(Node other) throws DOMException {

         DOMException ex = new DOMException(

           DOMException.NOT_SUPPORTED_ERR,

           "DOM level 3 interfaces are not fully implemented in Jaxen's NamespaceNode class"

         );

         throw ex;

     }

     /**

      * Return the namespace URI.

      *

      * @return the namespace URI

      * @see #getNodeValue

      */

     public String getTextContent() {

         return value;

     }

     /**

      * Change the value of this node (always fails).

      * This method is included solely for compatibility with the superclass.

      *

      * @param textContent the new content

      * @throws DOMException always

      */

     public void setTextContent(String textContent) throws DOMException {

         disallowModification();

     }

     /**

      * Returns true if and only if this object represents the same XPath namespace node

      * as the argument; that is, they have the same parent, the same prefix, and the

      * same URI.

      * 

      * @param other the node to compare to

      * @return true if this object represents the same XPath namespace node

      *     as other; false otherwise

      */

     public boolean isSameNode(Node other)  {

         boolean a = this.isEqualNode(other);

         // a bit flaky (should really be 

         // this.getParentNode().isEqual(other.getParentNode())

         // but we want this to compile in Java 1.4 without problems

         // Note that this will mess up code coverage since you can't cover both

         // branches in the same VM

         boolean b;