/*
 * Copyright 2001 (C) MetaStuff, Ltd. All Rights Reserved.
 * 
 * This software is open source. 
 * See the bottom of this file for the licence.
 * 
 * $Id: QName.java,v 1.9 2001/08/15 12:02:00 jstrachan Exp $
 */

package org.dom4j;

import java.io.IOException;
import java.io.Serializable;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

import org.dom4j.tree.QNameCache;

/** <p><code>QName</code> represents a qualified name value of an XML element 
  * or attribute. It consists of a local name and a {@link Namespace} 
  * instance. This object is immutable.</p>
  *
  * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
  * @version $Revision: 1.9 $
  */
public class QName implements Serializable {

    protected transient static QNameCache cache = new QNameCache();
    
    
    /** The local name of the element or attribute */
    private String name;
    
    /** The qualified name of the element or attribute */
    private String qualifiedName;
    
    /** The Namespace of this element or attribute */
    private transient Namespace namespace;
    
    /** A cached version of the hashcode for efficiency */
    private int hashCode;
    
    /** The document factory used for this QName if specified or null */
    private DocumentFactory documentFactory;

    
    public static synchronized QName get(String name) {
        return cache.get(name);
    }
    
    public static synchronized QName get(String name, Namespace namespace) {
        return cache.get(name, namespace);
    }
    
    public static synchronized QName get(String name, String prefix, String uri) {
        return cache.get(name, Namespace.get( prefix, uri ));
    }
    
    public static synchronized QName get(String qualifiedName, String uri) {
        return cache.get(qualifiedName, uri);
    }
    
    public static synchronized QName get(String localName, Namespace namespace, String qualifiedName) {
        return cache.get(localName, namespace, qualifiedName);
    }
    
    public QName(String name) {
        this( name, Namespace.NO_NAMESPACE );
    }
    
    public QName(String name, Namespace namespace) {
        this.name = (name == null) ? "" : name;
        this.namespace = (namespace == null) ? Namespace.NO_NAMESPACE : namespace;
    }

    public QName(String name, Namespace namespace, String qualifiedName) {
        this.name = (name == null) ? "" : name;
        this.qualifiedName = qualifiedName;
        this.namespace = (namespace == null) ? Namespace.NO_NAMESPACE : namespace;
    }

    
    /** @return the local name
      */
    public String getName() {
        return name;
    }
    
    /** @return the qualified name in the format <code>prefix:localName</code>
      */
    public String getQualifiedName() {
        if ( qualifiedName == null ) {
            String prefix = getNamespacePrefix();
            if ( prefix != null && prefix.length() > 0 ) {
                qualifiedName = prefix + ":" + name;
            }
            else {
                qualifiedName = name;
            }
        }
        return qualifiedName;
    }
    
    /** @return the namespace of this QName 
      */
    public Namespace getNamespace() {
        return namespace;
    }
        
    /** @return the namespace URI of this QName
      */
    public String getNamespacePrefix() {
        if ( namespace == null ) {
            return "";
        }
        return namespace.getPrefix();
    }
        
    /** @return the namespace URI of this QName
      */
    public String getNamespaceURI() {
        if ( namespace == null ) {
            return "";
        }
        return namespace.getURI();
    }
        
    
    /** @return the hash code based on the qualified name and the URI of the 
      * namespace.
      */
    public int hashCode() {
        if ( hashCode == 0 ) {
            hashCode = getName().hashCode() 
                ^ getNamespaceURI().hashCode();
            if ( hashCode == 0 ) {
                hashCode = 0xbabe;
            }
        }
        return hashCode;
    }
  
    public boolean equals(Object object) {
        if ( this == object ) {
            return true;
        }
        else if ( object instanceof QName ) {
            QName that = (QName) object;
            // we cache hash codes so this should be quick
            if ( hashCode() == that.hashCode() ) {
                return getName().equals( that.getName() )
                    && getNamespaceURI().equals( that.getNamespaceURI());
            }
        }
        return false;
    }
    
    public String toString() {
        return super.toString() + " [name: " + getName() 
            + " namespace: \"" + getNamespace() + "\"]";
    }

    /** @return the factory that should be used for Elements of this QName */
    public DocumentFactory getDocumentFactory() {
        return documentFactory;
    }

    public void setDocumentFactory(DocumentFactory documentFactory) {
        this.documentFactory = documentFactory;
    }
    
    private void writeObject(ObjectOutputStream out) throws IOException {

        // We use writeObject() and not writeUTF() to minimize space
        // This allows for writing pointers to already written strings
        out.writeObject(namespace.getPrefix());
        out.writeObject(namespace.getURI());
        
        out.defaultWriteObject();
    }
        
    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        
        String prefix = (String) in.readObject();
        String uri = (String) in.readObject();
        
        in.defaultReadObject();

        namespace = Namespace.get( prefix, uri );
    }


}




/*
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright
 *    statements and notices.  Redistributions must also contain a
 *    copy of this document.
 *
 * 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 name "DOM4J" must not be used to endorse or promote
 *    products derived from this Software without prior written
 *    permission of MetaStuff, Ltd.  For written permission,
 *    please contact dom4j-info@metastuff.com.
 *
 * 4. Products derived from this Software may not be called "DOM4J"
 *    nor may "DOM4J" appear in their names without prior written
 *    permission of MetaStuff, Ltd. DOM4J is a registered
 *    trademark of MetaStuff, Ltd.
 *
 * 5. Due credit should be given to the DOM4J Project
 *    (http://dom4j.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS
 * ``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
 * METASTUFF, LTD. OR ITS 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.
 *
 * Copyright 2001 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * $Id: QName.java,v 1.9 2001/08/15 12:02:00 jstrachan Exp $
 */