/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * Copyright 1999-2004 The Apache Software Foundation.

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

/*

 * $Id: XNull.java,v 1.2.4.1 2005/09/14 20:34:46 jeffsuttor Exp $

 */

package com.sun.org.apache.xpath.internal.objects;

import com.sun.org.apache.xml.internal.dtm.DTM;

import com.sun.org.apache.xpath.internal.XPathContext;

/**

 * This class represents an XPath null object, and is capable of

 * converting the null to other types, such as a string.

 * @xsl.usage general

 */

public class XNull extends XNodeSet

{

    static final long serialVersionUID = -6841683711458983005L;

  /**

   * Create an XObject.

   */

  public XNull()

  {

    super();

  }

  /**

   * Tell what kind of class this is.

   *

   * @return type CLASS_NULL

   */

  public int getType()

  {

    return CLASS_NULL;

  }

  /**

   * Given a request type, return the equivalent string.

   * For diagnostic purposes.

   *

   * @return type string "#CLASS_NULL"

   */

  public String getTypeString()

  {

    return "#CLASS_NULL";

  }

  /**

   * Cast result object to a number.

   *

   * @return 0.0

   */

  public double num()

  {

    return 0.0;

  }

  /**

   * Cast result object to a boolean.

   *

   * @return false

   */

  public boolean bool()

  {

    return false;

  }

  /**

   * Cast result object to a string.

   *

   * @return empty string ""

   */

  public String str()

  {

    return "";

  }

  /**

   * Cast result object to a result tree fragment.

   *

   * @param support XPath context to use for the conversion

   *

   * @return The object as a result tree fragment.

   */

  public int rtf(XPathContext support)

  {

    // DTM frag = support.createDocumentFragment();

    // %REVIEW%

    return DTM.NULL;

  }

//  /**

//   * Cast result object to a nodelist.

//   *

//   * @return null

//   */

//  public DTMIterator iter()

//  {

//    return null;

//  }

  /**

   * Tell if two objects are functionally equal.

   *

   * @param obj2 Object to compare this to

   *

   * @return True if the given object is of type CLASS_NULL

   */

  public boolean equals(XObject obj2)

  {

    return obj2.getType() == CLASS_NULL;

  }

}