code: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership. The ASF licenses this file
   * to you 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.
   */
  /*
   * $Id$
   */
  package org.apache.xpath.objects;
  
  import org.apache.xpath.ExpressionOwner;
  import org.apache.xpath.XPathContext;
  import org.apache.xpath.XPathVisitor;
  
  /**
   * This class represents an XPath number, and is capable of
   * converting the number to other types, such as a string.
   * @xsl.usage general
   */
  public class XNumber extends XObject
  {
      static final long serialVersionUID = -2720400709619020193L;
  
    /** Value of the XNumber object.
     *  @serial         */
    double m_val;
  
    /**
     * Construct a XNodeSet object.
     *
     * @param d Value of the object
     */
    public XNumber(double d)
    {
      super();
  
      m_val = d;
    }
    
    /**
     * Construct a XNodeSet object.
     *
     * @param num Value of the object
     */
    public XNumber(Number num)
    {
  
      super();
  
      m_val = num.doubleValue();
      setObject(num);
    }
  
    /**
     * Tell that this is a CLASS_NUMBER.
     *
     * @return node type CLASS_NUMBER 
     */
    public int getType()
    {
      return CLASS_NUMBER;
    }
  
    /**
     * Given a request type, return the equivalent string.
     * For diagnostic purposes.
     *
     * @return type string "#NUMBER" 
     */
    public String getTypeString()
    {
      return "#NUMBER";
    }
  
    /**
     * Cast result object to a number.
     *
     * @return the value of the XNumber object
     */
    public double num()
    {
      return m_val;
    }
    
    /**
     * Evaluate expression to a number.
     *
     * @return 0.0
     *
     * @throws javax.xml.transform.TransformerException
     */
    public double num(XPathContext xctxt) 
      throws javax.xml.transform.TransformerException
    {
  
      return m_val;
    }
  
    /**
     * Cast result object to a boolean.
     *
     * @return false if the value is NaN or equal to 0.0
     */
    public boolean bool()
    {
      return (Double.isNaN(m_val) || (m_val == 0.0)) ? false : true;
    }
  
  //  /**
  //   * Cast result object to a string.
  //   *
  //   * @return "NaN" if the number is NaN, Infinity or -Infinity if
  //   * the number is infinite or the string value of the number.
  //   */
  //  private static final int PRECISION = 16;
  //  public String str()
  //  {
  //
  //    if (Double.isNaN(m_val))
  //    {
  //      return "NaN";
  //    }
  //    else if (Double.isInfinite(m_val))
  //    {
  //      if (m_val > 0)
  //        return "Infinity";
  //      else
  //        return "-Infinity";
  //    }
  //
  //    long longVal = (long)m_val;
  //    if ((double)longVal == m_val)
  //      return Long.toString(longVal);
  //
  //
  //    String s = Double.toString(m_val);
  //    int len = s.length();
  //
  //    if (s.charAt(len - 2) == '.' && s.charAt(len - 1) == '0')
  //    {
  //      return s.substring(0, len - 2);
  //    }
  //
  //    int exp = 0;
  //    int e = s.indexOf('E');
  //    if (e != -1)
  //    {
  //      exp = Integer.parseInt(s.substring(e + 1));
  //      s = s.substring(0,e);
  //      len = e;
  //    }
  //
  //    // Calculate Significant Digits:
  //    // look from start of string for first digit
  //    // look from end for last digit
  //    // significant digits = end - start + (0 or 1 depending on decimal location)
  //
  //    int decimalPos = -1;
  //    int start = (s.charAt(0) == '-') ? 1 : 0;
  //    findStart: for( ; start < len; start++ )
  //    {
  //      switch (s.charAt(start))
  //      {
  //      case '0':
  //        break;
  //      case '.':
  //        decimalPos = start;
  //        break;
  //      default:
  //        break findStart;
  //      }
  //    }
  //    int end = s.length() - 1;
  //    findEnd: for( ; end > start; end-- )
  //    {
  //      switch (s.charAt(end))
  //      {
  //      case '0':
  //        break;
  //      case '.':
  //        decimalPos = end;
  //        break;
  //      default:
  //        break findEnd;
  //      }
  //    }
  //
  //    int sigDig = end - start;
  //
  //    // clarify decimal location if it has not yet been found
  //    if (decimalPos == -1)
  //      decimalPos = s.indexOf('.');
  //
  //    // if decimal is not between start and end, add one to sigDig
  //    if (decimalPos < start || decimalPos > end)
  //      ++sigDig;
  //
  //    // reduce significant digits to PRECISION if necessary
  //    if (sigDig > PRECISION)
  //    {
  //      // re-scale BigDecimal in order to get significant digits = PRECISION
  //      BigDecimal num = new BigDecimal(s);
  //      int newScale = num.scale() - (sigDig - PRECISION);
  //      if (newScale < 0)
  //        newScale = 0;
  //      s = num.setScale(newScale, BigDecimal.ROUND_HALF_UP).toString();
  //
  //      // remove trailing '0's; keep track of decimalPos
  //      int truncatePoint = s.length();
  //      while (s.charAt(--truncatePoint) == '0')
  //        ;
  //
  //      if (s.charAt(truncatePoint) == '.')
  //      {
  //        decimalPos = truncatePoint;
  //      }
  //      else
  //      {
  //        decimalPos = s.indexOf('.');
  //        truncatePoint += 1;
  //      }
  //
  //      s = s.substring(0, truncatePoint);
  //      len = s.length();
  //    }
  //
  //    // Account for exponent by adding zeros as needed 
  //    // and moving the decimal place
  //
  //    if (exp == 0)
  //       return s;
  //
  //    start = 0;
  //    String sign;
  //    if (s.charAt(0) == '-')
  //    {
  //      sign = "-";
  //      start++;
  //    }
  //    else
  //      sign = "";
  //
  //    String wholePart = s.substring(start, decimalPos);
  //    String decimalPart = s.substring(decimalPos + 1);
  //
  //    // get the number of digits right of the decimal
  //    int decimalLen = decimalPart.length();
  //
  //    if (exp >= decimalLen)
  //      return sign + wholePart + decimalPart + zeros(exp - decimalLen);
  //
  //    if (exp > 0)
  //      return sign + wholePart + decimalPart.substring(0, exp) + "."
  //             + decimalPart.substring(exp);
  //
  //    return sign + "0." + zeros(-1 - exp) + wholePart + decimalPart;
  //  }
  
    /**
     * Cast result object to a string.
     *
     * @return "NaN" if the number is NaN, Infinity or -Infinity if
     * the number is infinite or the string value of the number.
     */
    public String str()
    {
  
      if (Double.isNaN(m_val))
      {
        return "NaN";
      }
      else if (Double.isInfinite(m_val))
      {
        if (m_val > 0)
          return "Infinity";
        else
          return "-Infinity";
      }
  
      double num = m_val;
      String s = Double.toString(num);
      int len = s.length();
  
      if (s.charAt(len - 2) == '.' && s.charAt(len - 1) == '0')
      {
        s = s.substring(0, len - 2);
  
        if (s.equals("-0"))
          return "0";
  
        return s;
      }
  
      int e = s.indexOf('E');
  
      if (e < 0)
      {
        if (s.charAt(len - 1) == '0')
          return s.substring(0, len - 1);
        else
          return s;
      }
  
      int exp = Integer.parseInt(s.substring(e + 1));
      String sign;
  
      if (s.charAt(0) == '-')
      {
        sign = "-";
        s = s.substring(1);
  
        --e;
      }
      else
        sign = "";
  
      int nDigits = e - 2;
  
      if (exp >= nDigits)
        return sign + s.substring(0, 1) + s.substring(2, e)
               + zeros(exp - nDigits);
  
      // Eliminate trailing 0's - bugzilla 14241
      while (s.charAt(e-1) == '0')
        e--;
           
      if (exp > 0)
        return sign + s.substring(0, 1) + s.substring(2, 2 + exp) + "."
               + s.substring(2 + exp, e);
  
      return sign + "0." + zeros(-1 - exp) + s.substring(0, 1)
             + s.substring(2, e);
    }
  
  
    /**
     * Return a string of '0' of the given length
     *
     *
     * @param n Length of the string to be returned
     *
     * @return a string of '0' with the given length
     */
    static private String zeros(int n)
    {
      if (n < 1)
        return "";
  
      char[] buf = new char[n];
  
      for (int i = 0; i < n; i++)
      {
        buf[i] = '0';
      }
  
      return new String(buf);
    }
  
    /**
     * Return a java object that's closest to the representation
     * that should be handed to an extension.
     *
     * @return The value of this XNumber as a Double object
     */
    public Object object()
    {
      if(null == m_obj)
        setObject(new Double(m_val));
      return m_obj;
    }
  
    /**
     * 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)
    {
  
      // In order to handle the 'all' semantics of 
      // nodeset comparisons, we always call the 
      // nodeset function.
      int t = obj2.getType();
      try
      {
  	    if (t == XObject.CLASS_NODESET)
  	      return obj2.equals(this);
  	    else if(t == XObject.CLASS_BOOLEAN)
  	      return obj2.bool() == bool();
  		else
  	       return m_val == obj2.num();
      }
      catch(javax.xml.transform.TransformerException te)
      {
        throw new org.apache.xml.utils.WrappedRuntimeException(te);
      }
    }
    
    /**
     * Tell if this expression returns a stable number that will not change during 
     * iterations within the expression.  This is used to determine if a proximity 
     * position predicate can indicate that no more searching has to occur.
     * 
     *
     * @return true if the expression represents a stable number.
     */
    public boolean isStableNumber()
    {
      return true;
    }
    
    /**
     * @see org.apache.xpath.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)
     */
    public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)
    {
    	visitor.visitNumberLiteral(owner, this);
    }
  
  
  }
  