/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999 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.w3c.dom.*;

import org.apache.xpath.XPathContext;

/**
 * <meta name="usage" content="general"/>
 * This class represents an XPath string object, and is capable of
 * converting the string to other types, such as a number.
 */
public class XString extends XObject
{

  /** Empty string XString object          */
  public static XString EMPTYSTRING = new XString("");

  /**
   * Construct a XNodeSet object.
   *
   * @param val String object this will wrap.
   */
  public XString(String val)
  {
    super(val);
  }

  /**
   * Tell that this is a CLASS_STRING.
   *
   * @return type CLASS_STRING
   */
  public int getType()
  {
    return CLASS_STRING;
  }

  /**
   * Given a request type, return the equivalent string.
   * For diagnostic purposes.
   *
   * @return type string "#STRING"
   */
  public String getTypeString()
  {
    return "#STRING";
  }

  /**
   * Cast a string to a number.
   *
   * @param s The string to convert
   *
   * @return 0.0 if the string is null, numeric value of the string
   * or NaN
   */
  public static double castToNum(String s)
  {

    double result;

    if (null == s)
      result = 0.0;
    else
    {
      try
      {

        /**
         * TODO: Adjust this for locale. Need to take into
         * account the lang parameter on the xsl:sort
         */

        // It seems we can not use this as it just parses the 
        // start of the string until it finds a non-number char, 
        // which is not what we want according to the XSLT spec.  
        // Also, I *think* this is a local-specific
        // parse, which is also not what we want according to the 
        // XSLT spec (see below).
        // NumberFormat formatter = NumberFormat.getNumberInstance();
        // result = formatter.parse(s.trim()).doubleValue();
        // The dumb XSLT spec says: "The number function should 
        // not be used for conversion of numeric data occurring 
        // in an element in an XML document unless the element 
        // is of a type that represents numeric data in a 
        // language-neutral format (which would typically be 
        // transformed into a language-specific format for 
        // presentation to a user). In addition, the number 
        // function cannot be used unless the language-neutral 
        // format used by the element is consistent with the 
        // XPath syntax for a Number."
        // So I guess we need to check, if the default local 
        // is french, does Double.valueOf use the local specific 
        // parse?  Or does it use the ieee parse?
        result = Double.valueOf(s.trim()).doubleValue();
      }

      // catch (ParseException e) 
      catch (NumberFormatException nfe)
      {
        result = Double.NaN;
      }
    }

    return result;
  }

  /**
   * Cast result object to a number.
   *
   * @return 0.0 if this string is null, numeric value of this string
   * or NaN
   */
  public double num()
  {
    return castToNum((String) m_obj);
  }

  /**
   * Cast result object to a boolean.
   *
   * @return True if the length of this string object is greater
   * than 0.
   */
  public boolean bool()
  {
    return str().length() > 0;
  }

  /**
   * Cast result object to a string.
   *
   * @return The string this wraps or the empty string if null
   */
  public String str()
  {
    return (null != m_obj) ? ((String) m_obj) : "";
  }

  /**
   * Cast result object to a result tree fragment.
   *
   * @param support Xpath context to use for the conversion 
   *
   * @return A document fragment with this string as a child node
   */
  public DocumentFragment rtree(XPathContext support)
  {

    DocumentFragment df =
      support.getDOMHelper().getDOMFactory().createDocumentFragment();
    Text textNode =
      support.getDOMHelper().getDOMFactory().createTextNode(str());

    df.appendChild(textNode);

    return df;
  }

  /**
   * Tell if two objects are functionally equal.
   *
   * @param obj2 Object to compare this to
   *
   * @return true if the two objects are equal
   *
   * @throws javax.xml.transform.TransformerException
   */
  public boolean equals(XObject obj2) throws javax.xml.transform.TransformerException
  {

    // In order to handle the 'all' semantics of 
    // nodeset comparisons, we always call the 
    // nodeset function.
    if (obj2.getType() == XObject.CLASS_NODESET)
      return obj2.equals(this);

    return str().equals(obj2.str());
  }
}