/*
 * DomEntity.java
 * Copyright (C) 1999,2000,2004 The Free Software Foundation
 * 
 * This file is part of GNU JAXP, a library.
 *
 * GNU JAXP is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * GNU JAXP is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Linking this library statically or dynamically with other modules is
 * making a combined work based on this library.  Thus, the terms and
 * conditions of the GNU General Public License cover the whole
 * combination.
 *
 * As a special exception, the copyright holders of this library give you
 * permission to link this library with independent modules to produce an
 * executable, regardless of the license terms of these independent
 * modules, and to copy and distribute the resulting executable under
 * terms of your choice, provided that you also meet, for each linked
 * independent module, the terms and conditions of the license of that
 * module.  An independent module is a module which is not derived from
 * or based on this library.  If you modify this library, you may extend
 * this exception to your version of the library, but you are not
 * obliged to do so.  If you do not wish to do so, delete this
 * exception statement from your version. 
 */

package gnu.xml.dom;

import org.w3c.dom.Entity;

/**
 * <p> "Entity" implementation.  This is a non-core DOM class, supporting the
 * "XML" feature.  There are two types of entities, neither of which works
 * particularly well in this API:</p><dl>
 *
 * <dt><em>Unparsed Entities</em></dt>
 *	<dd>Since ENTITY/ENTITIES attributes, the only legal use of unparsed
 *	entities in XML, can't be detected with DOM, there isn't much point in
 *	trying to use unparsed entities in DOM applications.  (XML Linking is
 *	working to provide a better version of this functionality.) </dd>
 *
 * <dt><em>Parsed Entities</em></dt>
 *	<dd> While the DOM specification permits nodes for parsed entities
 *	to have a readonly set of children, this is not required and there
 *	is no portable way to provide such children.  <em>This implementation
 *	currently does not permit children to be added to Entities.</em>
 *	There are related issues with the use of EntityReference nodes.  </dd>
 *
 * </dl>
 *
 * <p> In short, <em>avoid using this DOM functionality</em>.
 *
 * @see DomDoctype
 * @see DomEntityReference
 * @see DomNotation
 *
 * @author David Brownell 
 * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
 */
public class DomEntity
  extends DomExtern
  implements Entity
{
  
  private String notation;

  /**
   * Constructs an Entity node associated with the specified document,
   * with the specified descriptive data.
   *
   * <p>This constructor should only be invoked by a DomDoctype as part
   * of its declareEntity functionality, or through a subclass which is
   * similarly used in a "Sub-DOM" style layer.
   *
   * @param owner The document with which this entity is associated
   * @param name Name of this entity
   * @param publicId If non-null, provides the entity's PUBLIC identifier
   * @param systemId Provides the entity's SYSTEM identifier (URI)
   * @param notation If non-null, provides the unparsed entity's notation.
   */
  protected DomEntity(DomDocument owner,
                      String name,
                      String publicId,
                      String systemId,
                      String notation)
  {
    super(ENTITY_NODE, owner, name, publicId, systemId);
    this.notation = notation;

    // NOTE:  if notation == null, this is a parsed entity
    // which could reasonably be given child nodes ...
    makeReadonly();
  }

  /**
   * <b>DOM L1</b>
   * Returns the NOTATION identifier associated with this entity, if any.
   */
  final public String getNotationName()
  {
    return notation;
  }

  // DOM Level 3 methods
  
  public String getInputEncoding()
  {
    // TODO
    return null;    
  }
  
  public String getXmlEncoding()
  {
    // TODO
    return null;
  }

  public String getXmlVersion()
  {
    // TODO
    return null;
  }

  /**
   * The base URI of an external entity is its system ID.
   * The base URI of an internal entity is the parent document's base URI.
   * @since DOM Level 3 Core
   */
  public String getBaseURI()
  {
    String systemId = getSystemId();
    return (systemId == null) ? owner.getBaseURI() : systemId;
  }
  
}

