/*

 ============================================================================
                   The Apache Software License, Version 1.1
 ============================================================================

 Copyright (C) 1999-2003 The Apache Software Foundation. All rights reserved.

 Redistribution and use in source and binary forms, with or without modifica-
 tion, 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 following disclaimer in the documentation
    and/or other materials provided with the distribution.

 3. The end-user documentation included with the redistribution, if any, must
    include  the following  acknowledgment:  "This product includes  software
    developed  by the  Apache Software Foundation  (http://www.apache.org/)."
    Alternately, this  acknowledgment may  appear in the software itself,  if
    and wherever such third-party acknowledgments normally appear.

 4. The names "Batik" and  "Apache Software Foundation" must  not  be
    used to  endorse or promote  products derived from  this software without
    prior written permission. For written permission, please contact
    apache@apache.org.

 5. Products  derived from this software may not  be called "Apache", nor may
    "Apache" appear  in their name,  without prior written permission  of the
    Apache Software Foundation.

 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
 APACHE SOFTWARE  FOUNDATION  OR ITS CONTRIBUTORS  BE LIABLE FOR  ANY DIRECT,
 INDIRECT, INCIDENTAL, SPECIAL,  EXEMPLARY, OR CONSEQUENTIAL  DAMAGES (INCLU-
 DING, 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 Apache Software  Foundation. For more  information on the
 Apache Software Foundation, please see <http://www.apache.org/>.

*/

package org.apache.batik.dom;

import java.io.Serializable;

import org.apache.batik.dom.util.DOMUtilities;
import org.w3c.dom.Attr;
import org.w3c.dom.DOMException;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.events.DocumentEvent;
import org.w3c.dom.events.MutationEvent;

/**
 * This class implements the {@link org.w3c.dom.Element} interface.
 *
 * @author <a href="mailto:stephane@hillion.org">Stephane Hillion</a>
 * @version $Id: AbstractElement.java,v 1.23 2003/09/23 18:11:47 nsochele Exp $
 */
public abstract class AbstractElement
    extends    AbstractParentChildNode
    implements Element {

    /**
     * The attributes of this element.
     */
    protected NamedNodeMap attributes;

    /**
     * Creates a new AbstractElement object.
     */
    protected AbstractElement() {
    }

    /**
     * Creates a new AbstractElement object.
     * @param name  The element name for validation purposes.
     * @param owner The owner document.
     * @exception DOMException
     *   INVALID_CHARACTER_ERR: if name contains invalid characters,
     */
    protected AbstractElement(String name, AbstractDocument owner) {
	ownerDocument = owner;
	if (!DOMUtilities.isValidName(name)) {
	    throw createDOMException(DOMException.INVALID_CHARACTER_ERR,
				     "xml.name",
				     new Object[] { name });
	}
    }

    /**
     * <b>DOM</b>: Implements {@link org.w3c.dom.Node#getNodeType()}.
     * @return {@link org.w3c.dom.Node#ELEMENT_NODE}
     */
    public short getNodeType() {
	return ELEMENT_NODE;
    }

    /**
     * <b>DOM</b>: Implements {@link org.w3c.dom.Node#hasAttributes()}.
     */
    public boolean hasAttributes() {
	return attributes != null && attributes.getLength() != 0;
    }

    /**
     * <b>DOM</b>: Implements {@link org.w3c.dom.Node#getAttributes()}.
     */
    public NamedNodeMap getAttributes() {
	return (attributes == null)
            ? attributes = createAttributes()
            : attributes;
    }

    /**
     * <b>DOM</b>: Implements {@link org.w3c.dom.Element#getTagName()}.
     * @return {@link #getNodeName()}.
     */
    public String getTagName() {
	return getNodeName();
    }

    /**
     * <b>DOM</b>: Implements {@link org.w3c.dom.Element#hasAttribute(String)}.
     */
    public boolean hasAttribute(String name) {
	return attributes != null && attributes.getNamedItem(name) != null;
    }

    /**
     * <b>DOM</b>: Implements {@link org.w3c.dom.Element#getAttribute(String)}.
     */
    public String getAttribute(String name) {
	if (attributes == null) {
	    return "";
	}
	Attr attr = (Attr)attributes.getNamedItem(name);
	return (attr == null) ? "" : attr.getValue();
    }

    /**
     * <b>DOM</b>: Implements {@link
     * org.w3c.dom.Element#setAttribute(String,String)}.
     */
    public void setAttribute(String name, String value) throws DOMException {
	if (attributes == null) {
	    attributes = createAttributes();
	}
        Attr attr = getAttributeNode(name);
        if (attr == null) {
            attr = getOwnerDocument().createAttribute(name);
            attr.setValue(value);
            attributes.setNamedItem(attr);
        } else {
            attr.setValue(value);
        }
    }

    /**
     * <b>DOM</b>: Implements {@link
     * org.w3c.dom.Element#removeAttribute(String)}.
     */
    public void removeAttribute(String name) throws DOMException {
	if (!hasAttribute(name)) {
            return;
	}
	attributes.removeNamedItem(name);
    }

    /**
     * <b>DOM</b>: Implements {@link
     * org.w3c.dom.Element#getAttributeNode(String)}.
     */
    public Attr getAttributeNode(String name) {
	if (attributes == null) {
	    return null;
	}
	return (Attr)attributes.getNamedItem(name);
    }

    /**
     * <b>DOM</b>: Implements {@link
     * org.w3c.dom.Element#setAttributeNode(Attr)}.
     */
    public Attr setAttributeNode(Attr newAttr) throws DOMException {
	if (newAttr == null) {
	    return null;
	}
	if (attributes == null) {
	    attributes = createAttributes();
	}
	return (Attr)attributes.setNamedItemNS(newAttr);
    }

    /**
     * <b>DOM</b>: Implements {@link
     * org.w3c.dom.Element#removeAttributeNode(Attr)}.
     */
    public Attr removeAttributeNode(Attr oldAttr) throws DOMException {
	if (oldAttr == null) {
	    return null;
	}
	if (attributes == null) {
	    throw createDOMException(DOMException.NOT_FOUND_ERR,
				     "attribute.missing",
				     new Object[] { oldAttr.getName() });
	}
        String nsURI = oldAttr.getNamespaceURI();
	return (Attr)attributes.removeNamedItemNS(nsURI,
                                                  (nsURI==null
                                                   ? oldAttr.getNodeName()
                                                   : oldAttr.getLocalName()));
    }

    /**
     * <b>DOM</b>: Implements {@link org.w3c.dom.Node#normalize()}.
     */
    public void normalize() {
	super.normalize();
	if (attributes != null) {
	    NamedNodeMap map = getAttributes();
	    for (int i = map.getLength() - 1; i >= 0; i--) {
		map.item(i).normalize();
	    }
	}
    }

    /**
     * <b>DOM</b>: Implements {@link
     * org.w3c.dom.Element#hasAttributeNS(String,String)}.
     */
    public boolean hasAttributeNS(String namespaceURI, String localName) {
	return attributes != null &&
	       attributes.getNamedItemNS(namespaceURI, localName) != null;
    }

    /**
     * <b>DOM</b>: Implements {@link
     * org.w3c.dom.Element#getAttributeNS(String,String)}.
     */
    public String getAttributeNS(String namespaceURI, String localName) {
	if (attributes == null) {
	    return "";
	}
	Attr attr = (Attr)attributes.getNamedItemNS(namespaceURI, localName);
	return (attr == null) ? "" : attr.getValue();
    }

    /**
     * <b>DOM</b>: Implements {@link
     * org.w3c.dom.Element#setAttributeNS(String,String,String)}.
     */
    public void setAttributeNS(String namespaceURI, 
			       String qualifiedName, 
			       String value) throws DOMException {
	if (attributes == null) {
	    attributes = createAttributes();
	}
        Attr attr = getAttributeNodeNS(namespaceURI, qualifiedName);
        if (attr == null) {
            attr = getOwnerDocument().createAttributeNS(namespaceURI,
                                                        qualifiedName);
            attr.setValue(value);
            attributes.setNamedItemNS(attr);
        } else {
            attr.setValue(value);
        }
    }

    /**
     * <b>DOM</b>: Implements {@link
     * org.w3c.dom.Element#removeAttributeNS(String,String)}.
     */
    public void removeAttributeNS(String namespaceURI, 
				  String localName) throws DOMException {
	if (!hasAttributeNS(namespaceURI, localName)) {
            return;
	}
	attributes.removeNamedItemNS(namespaceURI, localName);
    }

    /**
     * <b>DOM</b>: Implements {@link
     * org.w3c.dom.Element#getAttributeNodeNS(String,String)}.
     */
    public Attr getAttributeNodeNS(String namespaceURI, 
				   String localName) {
	if (attributes == null) {
	    return null;
	}
	return (Attr)attributes.getNamedItemNS(namespaceURI, localName);
    }

    /**
     * <b>DOM</b>: Implements {@link
     * org.w3c.dom.Element#setAttributeNodeNS(Attr)}.
     */
    public Attr setAttributeNodeNS(Attr newAttr) throws DOMException {
	if (newAttr == null) {
	    return null;
	}
	if (attributes == null) {
	    attributes = createAttributes();
	}
	return (Attr)attributes.setNamedItemNS(newAttr);
    }

    /**
     * Called when a child node has been added.
     */
    protected void nodeAdded(Node node) {
        invalidateElementsByTagName(node);
    }

    /**
     * Called when a child node is going to be removed.
     */
    protected void nodeToBeRemoved(Node node) {
        invalidateElementsByTagName(node);
    }

    /**
     * Invalidates the ElementsByTagName objects of this node and its parents.
     */
    private void invalidateElementsByTagName(Node node) {
        if (node.getNodeType() != ELEMENT_NODE) {
            return;
        }
        AbstractDocument ad = getCurrentDocument();
        String ns = node.getNamespaceURI();
        String nm = node.getNodeName();
        String ln = (ns == null) ? node.getNodeName() : node.getLocalName();
        for (Node n = this; n != null; n = n.getParentNode()) {
            switch (n.getNodeType()) {
            case ELEMENT_NODE:
            case DOCUMENT_NODE:
                ElementsByTagName l = ad.getElementsByTagName(n, nm);
                if (l != null) {
                    l.invalidate();
                }
                l = ad.getElementsByTagName(n, "*");
                if (l != null) {
                    l.invalidate();
                }
                ElementsByTagNameNS lns = ad.getElementsByTagNameNS(n, ns, ln);

                if (lns != null) {
                    lns.invalidate();
                }
                lns = ad.getElementsByTagNameNS(n, "*", ln);
                if (lns != null) {
                    lns.invalidate();
                }
                lns = ad.getElementsByTagNameNS(n, ns, "*");
                if (lns != null) {
                    lns.invalidate();
                }
                lns = ad.getElementsByTagNameNS(n, "*", "*");
                if (lns != null) {
                    lns.invalidate();
                }
            }
        }

        //
        // Invalidate children
        //
        Node c = node.getFirstChild();
        while (c != null) {
            invalidateElementsByTagName(c);
            c = c.getNextSibling();
        }
            
    }

    /**
     * Creates the attribute list.
     */
    protected NamedNodeMap createAttributes() {
	return new NamedNodeHashMap();
    }

    /**
     * Exports this node to the given document.
     * @param n The clone node.
     * @param d The destination document.
     */
    protected Node export(Node n, AbstractDocument d) {
	super.export(n, d);
	AbstractElement ae = (AbstractElement)n;
	if (attributes != null) {
	    NamedNodeMap map = attributes;
	    for (int i = map.getLength() - 1; i >= 0; i--) {
		AbstractAttr aa = (AbstractAttr)map.item(i);
		if (aa.getSpecified()) {
		    Attr attr = (Attr)aa.deepExport(aa.cloneNode(false), d);
		    if (aa instanceof AbstractAttrNS) {
			ae.setAttributeNodeNS(attr);
		    } else {
			ae.setAttributeNode(attr);
		    }
		}
	    }
	}
	return n;
    }

    /**
     * Deeply exports this node to the given document.
     * @param n The clone node.
     * @param d The destination document.
     */
    protected Node deepExport(Node n, AbstractDocument d) {
	super.deepExport(n, d);
	AbstractElement ae = (AbstractElement)n;
	if (attributes != null) {
	    NamedNodeMap map = attributes;
	    for (int i = map.getLength() - 1; i >= 0; i--) {
		AbstractAttr aa = (AbstractAttr)map.item(i);
		if (aa.getSpecified()) {
		    Attr attr = (Attr)aa.deepExport(aa.cloneNode(false), d);
		    if (aa instanceof AbstractAttrNS) {
			ae.setAttributeNodeNS(attr);
		    } else {
			ae.setAttributeNode(attr);
		    }
		}
	    }
	}
	return n;
    }

    /**
     * Copy the fields of the current node into the given node.
     * @param n a node of the type of this.
     */
    protected Node copyInto(Node n) {
	super.copyInto(n);
	AbstractElement ae = (AbstractElement)n;
	if (attributes != null) {
	    NamedNodeMap map = attributes;
	    for (int i = map.getLength() - 1; i >= 0; i--) {
		AbstractAttr aa = (AbstractAttr)map.item(i).cloneNode(true);
		if (aa instanceof AbstractAttrNS) {
		    ae.setAttributeNodeNS(aa);
		} else {
		    ae.setAttributeNode(aa);
		}
	    }
	}
	return n;
    }

    /**
     * Deeply copy the fields of the current node into the given node.
     * @param n a node of the type of this.
     */
    protected Node deepCopyInto(Node n) {
	super.deepCopyInto(n);
	AbstractElement ae = (AbstractElement)n;
	if (attributes != null) {
	    NamedNodeMap map = attributes;
	    for (int i = map.getLength() - 1; i >= 0; i--) {
		AbstractAttr aa = (AbstractAttr)map.item(i).cloneNode(true);
		if (aa instanceof AbstractAttrNS) {
		    ae.setAttributeNodeNS(aa);
		} else {
		    ae.setAttributeNode(aa);
		}
	    }
	}
	return n;
    }

    /**
     * Checks the validity of a node to be inserted.
     * @param n The node to be inserted.
     */
    protected void checkChildType(Node n, boolean replace) {
	switch (n.getNodeType()) {
	case ELEMENT_NODE:
	case PROCESSING_INSTRUCTION_NODE:
	case COMMENT_NODE:
	case TEXT_NODE:
	case CDATA_SECTION_NODE:
	case ENTITY_REFERENCE_NODE:
	case DOCUMENT_FRAGMENT_NODE:
	    break;
	default:
	    throw createDOMException
                (DOMException.HIERARCHY_REQUEST_ERR,
                 "child.type",
                 new Object[] { new Integer(getNodeType()),
                                getNodeName(),
                                new Integer(n.getNodeType()),
                                n.getNodeName() });
	}
    }

    /**
     * Fires a DOMAttrModified event.
     * <!> WARNING: public accessor because of compilation problems
     *     on Solaris. Do not change.
     *
     * @param name The attribute's name.
     * @param node The attribute's node.
     * @param oldv The old value of the attribute.
     * @param newv The new value of the attribute.
     * @param change The modification type.
     */
    public void fireDOMAttrModifiedEvent(String name, Attr node, String oldv,
                                         String newv, short change) {
        switch (change) {
        case MutationEvent.ADDITION:
            attrAdded(node, newv);
            break;

        case MutationEvent.MODIFICATION:
            attrModified(node, oldv, newv);
            break;

        default: // MutationEvent.REMOVAL:
            attrRemoved(node, oldv);
        }
	AbstractDocument doc = getCurrentDocument();
	if (doc.getEventsEnabled() && !oldv.equals(newv)) {
	    DocumentEvent de = (DocumentEvent)doc;
	    MutationEvent ev = (MutationEvent)de.createEvent("MutationEvents");
	    ev.initMutationEvent("DOMAttrModified",
				 true,    // canBubbleArg
				 false,   // cancelableArg
				 node,    // relatedNodeArg
				 oldv,    // prevValueArg
				 newv,    // newValueArg
				 name,    // attrNameArg
                                 change); // attrChange
	    dispatchEvent(ev);
	}
    }

    /**
     * Called when an attribute has been added.
     */
    protected void attrAdded(Attr node, String newv) {
    }

    /**
     * Called when an attribute has been modified.
     */
    protected void attrModified(Attr node, String oldv, String newv) {
    }

    /**
     * Called when an attribute has been removed.
     */
    protected void attrRemoved(Attr node, String oldv) {
    }

    /**
     * An implementation of the {@link org.w3c.dom.NamedNodeMap}.
     */
    public class NamedNodeHashMap implements NamedNodeMap, Serializable {

        /**
         * The initial capacity
         */
        protected final static int INITIAL_CAPACITY = 3;

        /**
         * The underlying array
         */
        protected Entry[] table;
	    
        /**
         * The number of entries
         */
        protected int count;
	    
	/**
	 * Creates a new NamedNodeHashMap object.
	 */
	public NamedNodeHashMap() {
            table = new Entry[INITIAL_CAPACITY];
	}

	/**
	 * <b>DOM</b>: Implements {@link
         * org.w3c.dom.NamedNodeMap#getNamedItem(String)}.
	 */
	public Node getNamedItem(String name) {
	    if (name == null) {
		return null;
	    }
	    return get(null, name);
	}

	/**
	 * <b>DOM</b>: Implements {@link
         * org.w3c.dom.NamedNodeMap#setNamedItem(Node)}.
	 */
	public Node setNamedItem(Node arg) throws DOMException {
	    if (arg == null) {
		return null;
	    }
	    checkNode(arg);

	    return setNamedItem(null, arg.getNodeName(), arg);
	}

	/**
	 * <b>DOM</b>: Implements {@link
	 * org.w3c.dom.NamedNodeMap#removeNamedItem(String)}.
	 */
	public Node removeNamedItem(String name) throws DOMException {
	    return removeNamedItemNS(null, name);
	}

	/**
	 * <b>DOM</b>: Implements {@link org.w3c.dom.NamedNodeMap#item(int)}.
	 */
	public Node item(int index) {
            if (index < 0 || index >= count) {
                return null;
            }
            int j = 0;
            for (int i = 0; i < table.length; i++) {
                Entry e = table[i];
                if (e == null) {
                    continue;
                }
                do {
                    if (j++ == index) {
                        return e.value;
                    }
                    e = e.next;
                } while (e != null);
            }
            return null;
	}

	/**
	 * <b>DOM</b>: Implements {@link org.w3c.dom.NamedNodeMap#getLength()}.
	 */
	public int getLength() {
            return count;
	}

	/**
	 * <b>DOM</b>: Implements {@link
	 * org.w3c.dom.NamedNodeMap#getNamedItemNS(String,String)}.
	 */
	public Node getNamedItemNS(String namespaceURI, String localName) {
            return get(namespaceURI, localName);
	}

	/**
	 * <b>DOM</b>: Implements {@link
         * org.w3c.dom.NamedNodeMap#setNamedItemNS(Node)}.
	 */
	public Node setNamedItemNS(Node arg) throws DOMException {
	    if (arg == null) {
		return null;
	    }
	    String nsURI = arg.getNamespaceURI();
            return setNamedItem(nsURI,
                                (nsURI == null) 
                                ? arg.getNodeName()
                                : arg.getLocalName(), arg);
	}

	/**
	 * <b>DOM</b>: Implements {@link
	 * org.w3c.dom.NamedNodeMap#removeNamedItemNS(String,String)}.
	 */
	public Node removeNamedItemNS(String namespaceURI, String localName)
	    throws DOMException {
	    if (isReadonly()) {
		throw createDOMException
                    (DOMException.NO_MODIFICATION_ALLOWED_ERR,
                     "readonly.node.map",
                     new Object[] {});
	    }
	    if (localName == null) {
		throw createDOMException(DOMException.NOT_FOUND_ERR,
					 "attribute.missing",
					 new Object[] { "" });
	    }
	    AbstractAttr n = (AbstractAttr)remove(namespaceURI, localName);
	    if (n == null) {
		throw createDOMException(DOMException.NOT_FOUND_ERR,
					 "attribute.missing",
					 new Object[] { localName });
	    }
	    n.setOwnerElement(null);
	    
	    // Mutation event
	    fireDOMAttrModifiedEvent(n.getNodeName(), n, n.getNodeValue(), "",
                                     MutationEvent.REMOVAL);
	    return n;
	}

	/**
	 * Adds a node to the map.
 	 */
	public Node setNamedItem(String ns, String name, Node arg)
            throws DOMException {
	    ((AbstractAttr)arg).setOwnerElement(AbstractElement.this);
	    AbstractAttr result = (AbstractAttr)put(ns, name, arg);

	    if (result != null) {
		result.setOwnerElement(null);
		fireDOMAttrModifiedEvent(name,
                                         result,
					 result.getNodeValue(),
					 "",
                                         MutationEvent.REMOVAL);
	    }
            fireDOMAttrModifiedEvent(name,
                                     (Attr)arg,
                                     "",
                                     arg.getNodeValue(),
                                     MutationEvent.ADDITION);
	    return result;
	}

	/**
	 * Checks the validity of a node to add.
	 */
	protected void checkNode(Node arg) {
	    if (isReadonly()) {
		throw createDOMException
                    (DOMException.NO_MODIFICATION_ALLOWED_ERR,
                     "readonly.node.map",
                     new Object[] {});
	    }
	    if (getOwnerDocument() != arg.getOwnerDocument()) {
		throw createDOMException(DOMException.WRONG_DOCUMENT_ERR,
					 "node.from.wrong.document",
					 new Object[] { new Integer
                                                         (arg.getNodeType()),
		                                        arg.getNodeName() });
	    }
	    if (arg.getNodeType() == ATTRIBUTE_NODE &&
		((Attr)arg).getOwnerElement() != null) {
		throw createDOMException(DOMException.WRONG_DOCUMENT_ERR,
					 "inuse.attribute",
					 new Object[] { arg.getNodeName() });
	    }
	}

        /**
         * Gets the value of a variable
         * @return the value or null
         */
        protected Node get(String ns, String nm) {
            int hash  = hashCode(ns, nm) & 0x7FFFFFFF;
            int index = hash % table.length;
	
            for (Entry e = table[index]; e != null; e = e.next) {
                if ((e.hash == hash) && e.match(ns, nm)) {
                    return e.value;
                }
            }
            return null;
        }
    
        /**
         * Sets a new value for the given variable
         * @return the old value or null
         */
        protected Node put(String ns, String nm, Node value) {
            int hash  = hashCode(ns, nm) & 0x7FFFFFFF;
            int index = hash % table.length;
	
            for (Entry e = table[index]; e != null; e = e.next) {
                if ((e.hash == hash) && e.match(ns, nm)) {
                    Node old = e.value;
                    e.value = value;
                    return old;
                }
            }
	
            // The key is not in the hash table
            int len = table.length;
            if (count++ >= (len * 3) >>> 2) {
                rehash();
                index = hash % table.length;
            }
            
            Entry e = new Entry(hash, ns, nm, value, table[index]);
            table[index] = e;
            return null;
        }

        /**
         * Removes an entry from the table.
         * @return the value or null.
         */
        protected Node remove(String ns, String nm) {
            int hash  = hashCode(ns, nm) & 0x7FFFFFFF;
            int index = hash % table.length;
	
            Entry p = null;
            for (Entry e = table[index]; e != null; e = e.next) {
                if ((e.hash == hash) && e.match(ns, nm)) {
                    Node result = e.value;
                    if (p == null) {
                        table[index] = e.next;
                    } else {
                        p.next = e.next;
                    }
                    count--;
                    return result;
                }
                p = e;
            }
            return null;
        }

        /**
         * Rehash the table
         */
        protected void rehash () {
            Entry[] oldTable = table;
	
            table = new Entry[oldTable.length * 2 + 1];
	
            for (int i = oldTable.length-1; i >= 0; i--) {
                for (Entry old = oldTable[i]; old != null;) {
                    Entry e = old;
                    old = old.next;
                    
                    int index = e.hash % table.length;
                    e.next = table[index];
                    table[index] = e;
                }
            }
        }

        /**
         * Computes a hash code corresponding to the given strings. 
         */
        protected int hashCode(String ns, String nm) {
            int result = (ns == null) ? 0 : ns.hashCode();
            return result ^ nm.hashCode();
        }
    }

    /**
     * To manage collisions in the attributes map.
     */
    protected static class Entry implements Serializable {

        /**
         * The hash code
         */
        public int hash;
	
        /**
         * The namespace URI
         */
        public String namespaceURI;
	
        /**
         * The node name.
         */
        public String name;
        
        /**
         * The value
         */
        public Node value;
	
        /**
         * The next entry
         */
        public Entry next;
	
        /**
         * Creates a new entry
         */
        public Entry(int hash, String ns, String nm, Node value, Entry next) {
            this.hash = hash;
            this.namespaceURI = ns;
            this.name = nm;
            this.value = value;
            this.next = next;
        }
        
        /**
         * Whether this entry match the given keys.
         */
        public boolean match(String ns, String nm) {
            if (namespaceURI != null) {
                if (!namespaceURI.equals(ns)) {
                    return false;
                }
            } else if (ns != null) {
                return false;
            }
            return name.equals(nm);
        }
    }

}
