/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999-2003 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 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 end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xalan" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``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 THE APACHE SOFTWARE FOUNDATION 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, Lotus
 * Development Corporation., http://www.lotus.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.xpath.objects;

import org.apache.xml.dtm.DTM;
import org.apache.xml.dtm.DTMIterator;
import org.apache.xml.dtm.DTMFilter;

import org.apache.xml.utils.XMLString;

import org.apache.xpath.XPathContext;
import org.apache.xpath.Expression;
import org.apache.xalan.res.XSLMessages;
import org.apache.xpath.res.XPATHErrorResources;

/**
 * This class makes an select statement act like an result tree fragment.
 */
public class XRTreeFragSelectWrapper extends XRTreeFrag implements Cloneable
{
  XObject m_selected;

  public XRTreeFragSelectWrapper(Expression expr)
  {
    super(expr);
  }
  
  /**
   * This function is used to fixup variables from QNames to stack frame 
   * indexes at stylesheet build time.
   * @param vars List of QNames that correspond to variables.  This list 
   * should be searched backwards for the first qualified name that 
   * corresponds to the variable reference qname.  The position of the 
   * QName in the vector from the start of the vector will be its position 
   * in the stack frame (but variables above the globalsTop value will need 
   * to be offset to the current stack frame).
   */
  public void fixupVariables(java.util.Vector vars, int globalsSize)
  {
    ((Expression)m_obj).fixupVariables(vars, globalsSize);
  }
  
  /**
   * For support of literal objects in xpaths.
   *
   * @param xctxt The XPath execution context.
   *
   * @return the result of executing the select expression
   *
   * @throws javax.xml.transform.TransformerException
   */
  public XObject execute(XPathContext xctxt)
          throws javax.xml.transform.TransformerException
  {
     m_selected = ((Expression)m_obj).execute(xctxt);
     m_selected.allowDetachToRelease(m_allowRelease);
     if (m_selected.getType() == CLASS_STRING)
       return m_selected;
     else
       return new XString(m_selected.str());
  }
    
  /**
   * Detaches the <code>DTMIterator</code> from the set which it iterated
   * over, releasing any computational resources and placing the iterator
   * in the INVALID state. After <code>detach</code> has been invoked,
   * calls to <code>nextNode</code> or <code>previousNode</code> will
   * raise a runtime exception.
   * 
   * In general, detach should only be called once on the object.
   */
  public void detach()
  {
    if(m_allowRelease)
    {
      m_selected.detach();
      m_selected = null;
    }
    
    super.detach();
  }
  
  /**
   * Cast result object to a number.
   *
   * @return The result tree fragment as a number or NaN
   */
  public double num()
    throws javax.xml.transform.TransformerException
  {

    return m_selected.num();
  }

  
  /**
   * Cast result object to an XMLString.
   *
   * @return The document fragment node data or the empty string. 
   */
  public XMLString xstr()
  {
    return m_selected.xstr();
  }

  /**
   * Cast result object to a string.
   *
   * @return The document fragment node data or the empty string. 
   */
  public String str()
  {
    return m_selected.str();
  }
  
  /**
   * Tell what kind of class this is.
   *
   * @return the string type
   */
  public int getType()
  {
    return CLASS_STRING;
  }

  /**
   * Cast result object to a result tree fragment.
   *
   * @return The document fragment this wraps
   */
  public int rtf()
  {
    throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_RTF_NOT_SUPPORTED_XRTREEFRAGSELECTWRAPPER, null)); //"rtf() not supported by XRTreeFragSelectWrapper!");
  }

  /**
   * Cast result object to a DTMIterator.
   *
   * @return The document fragment as a DTMIterator
   */
  public DTMIterator asNodeIterator()
  {
    throw new RuntimeException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_RTF_NOT_SUPPORTED_XRTREEFRAGSELECTWRAPPER, null)); //"asNodeIterator() not supported by XRTreeFragSelectWrapper!");
  }

}