/*
    * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
    *
    * This software is open source.
    * See the bottom of this file for the licence.
    */
   
   package org.dom4j;
   
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.io.Serializable;
  
  import org.dom4j.tree.QNameCache;
  import org.dom4j.util.SingletonStrategy;
  
  /**
   * <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>
   */
  public class QName implements Serializable {
      /** The Singleton instance */
      private static SingletonStrategy singleton = null;
  
      static {
          try {
              String defaultSingletonClass = "org.dom4j.util.SimpleSingleton";
              Class clazz = null;
              try {
                  String singletonClass = defaultSingletonClass;
                  singletonClass = System.getProperty(
                          "org.dom4j.QName.singleton.strategy", singletonClass);
                  clazz = Class.forName(singletonClass);
              } catch (Exception exc1) {
                  try {
                      String singletonClass = defaultSingletonClass;
                      clazz = Class.forName(singletonClass);
                  } catch (Exception exc2) {
                  }
              }
              singleton = (SingletonStrategy) clazz.newInstance();
              singleton.setSingletonClassName(QNameCache.class.getName());
          } catch (Exception exc3) {
          }
      }
  
      /** 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 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;
      }
  
      public static QName get(String name) {
          return getCache().get(name);
      }
  
      public static QName get(String name, Namespace namespace) {
          return getCache().get(name, namespace);
      }
  
      public static QName get(String name, String prefix, String uri) {
          if (((prefix == null) || (prefix.length() == 0)) && (uri == null)) {
              return QName.get(name);
          } else if ((prefix == null) || (prefix.length() == 0)) {
              return getCache().get(name, Namespace.get(uri));
          } else if (uri == null) {
              return QName.get(name);
         } else {
             return getCache().get(name, Namespace.get(prefix, uri));
         }
     }
 
     public static QName get(String qualifiedName, String uri) {
         if (uri == null) {
             return getCache().get(qualifiedName);
         } else {
             return getCache().get(qualifiedName, uri);
         }
     }
 
     public static QName get(String localName, Namespace namespace,
             String qualifiedName) {
         return getCache().get(localName, namespace, qualifiedName);
     }
 
     /**
      * DOCUMENT ME!
      * 
      * @return the local name
      */
     public String getName() {
         return name;
     }
 
     /**
      * DOCUMENT ME!
      * 
      * @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;
     }
 
     /**
      * DOCUMENT ME!
      * 
      * @return the namespace of this QName
      */
     public Namespace getNamespace() {
         return namespace;
     }
 
     /**
      * DOCUMENT ME!
      * 
      * @return the namespace URI of this QName
      */
     public String getNamespacePrefix() {
         if (namespace == null) {
             return "";
         }
 
         return namespace.getPrefix();
     }
 
     /**
      * DOCUMENT ME!
      * 
      * @return the namespace URI of this QName
      */
     public String getNamespaceURI() {
         if (namespace == null) {
             return "";
         }
 
         return namespace.getURI();
     }
 
     /**
      * DOCUMENT ME!
      * 
      * @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() + "\"]";
     }
 
     /**
      * DOCUMENT ME!
      * 
      * @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);
     }
 
     private static QNameCache getCache() {
         QNameCache cache = (QNameCache) singleton.instance();
         return cache;
     }
 }
 
 
 
 /*
  * 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://www.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 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
  */