Meta.java

/*
 * This file or a portion of this file is licensed under the terms of
 * the Globus Toolkit Public License, found in file ../GTPL, or at
 * http://www.globus.org/toolkit/download/license.html. This notice must
 * appear in redistributions of this file, with or without modification.
 *
 * Redistributions of this Software, with or without modification, must
 * reproduce the GTPL in: (1) the Software, or (2) the Documentation or
 * some other similar material which is provided with the Software (if
 * any).
 *
 * Copyright 1999-2004 University of Chicago and The University of
 * Southern California. All rights reserved.
 */

package org.griphyn.vdl.classes;

import org.griphyn.vdl.classes.*;
import java.util.*;
import java.io.IOException;
import java.io.Writer;
import java.io.Serializable;

/**
 * This class implements nothing for meta data.
 *
 * @author Jens-S. Vöckler
 * @author Yong Zhao
 * @version $Revision$
 */
public class Meta extends VDL implements Serializable
{
  /**
   * Stores the content of whatever.
   */
  private String m_content;

  /**
   * Default ctor. Calls the parent initialization.
   */
  public Meta()
  { 
    super();
    this.m_content = new String();
  }

  /**
   * Ctor to initialize the content while constructing the class.
   * This is a convenience ctor.
   */
  public Meta( String content )
  { 
    super();
    this.m_content = content;
  }

  /**
   * Appends text to the current internal state. The text may contain
   * other elements which are not quoted or changed in any way.
   *
   * @param content is the new text to append to the current content. 
   * @see #getContent()
   */
  public void addContent( String content )
  { 
    this.m_content += content; 
  }

  /**
   * Gets the content state of this object. The text may contain
   * other elements which are not quoted or changed in any way.
   *
   * @return The current state of content. The text may be null.
   * @see #setContent(String)
   */
  public String getContent()
  { 
    return this.m_content; 
  }

  /**
   * Overwrites the internal state with new content. The supplied content
   * will become effectively the active state of the object. Usually, this
   * method will be called during SAX assembly of the instance structure.
   *
   * @param content is the new state to register.
   * @see #getContent()
   **/
  public void setContent( String content )
  { 
    this.m_content = content; 
  }

  /**
   * Converts the active state into something meant for human consumption.
   * This method overwrites the base class default as it can be more 
   * efficiently implemented.
   *
   * @return There is not textual representation of metadata in VDLt.
   */
  public String toString()
  { 
    return new String();
  }

  /**
   * Prints the current content onto the stream. This is a no-op, because
   * there is not textual representation of metadata in VDLt.
   *
   * @param stream is a stream opened and ready for writing. This can also
   * be a string stream for efficient output.
   * @throws IOException if something happens to the stream.
   */
  public void toString( Writer stream )
    throws IOException 
  {
    // do nothing
  }

  /**
   * Dump the state of the current element as XML output. The stream
   * interface should be able to handle large output efficiently, if you
   * use a buffered writer.
   *
   * @param stream is a stream opened and ready for writing. This can also
   * be a string stream for efficient output.
   * @param indent is a <code>String</code> of spaces used for pretty
   * printing. The initial amount of spaces should be an empty string.
   * The parameter is used internally for the recursive traversal.
   * @param namespace is the XML schema namespace prefix. If neither
   * empty nor null, each element will be prefixed with this prefix,
   * and the root element will map the XML namespace. 
   * @exception IOException if something fishy happens to the stream.
   */
  public void toXML( Writer stream, String indent, String namespace )
    throws IOException
  {
    String tag = ( namespace != null && namespace.length() > 0 ) ?
      namespace + ":meta" : "meta";

    // just one tag
    if ( indent != null && indent.length() > 0 ) stream.write( indent );
    stream.write( '<' );
    stream.write( tag );
    if ( this.m_content.length() > 0 ) {
      stream.write( '>' );
      stream.write( quote(this.m_content,false) );
      stream.write( "</" );
      stream.write( tag );
      stream.write( '>' );
    } else {
      stream.write( "/>" );
    }
    if ( indent != null ) 
      stream.write( System.getProperty( "line.separator", "\r\n" ) );
  }
}