xstringforfsb.java

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  /**
   * Returns the index within this string of the first occurrence of the
   * specified character, starting the search at the specified index.
   * <p>
   * If a character with value <code>ch</code> occurs in the character
   * sequence represented by this <code>String</code> object at an index
   * no smaller than <code>fromIndex</code>, then the index of the first
   * such occurrence is returned--that is, the smallest value <i>k</i>
   * such that:
   * <blockquote><pre>
   * (this.charAt(<i>k</i>) == ch) && (<i>k</i> >= fromIndex)
   * </pre></blockquote>
   * is true. If no such character occurs in this string at or after
   * position <code>fromIndex</code>, then <code>-1</code> is returned.
   * <p>
   * There is no restriction on the value of <code>fromIndex</code>. If it
   * is negative, it has the same effect as if it were zero: this entire
   * string may be searched. If it is greater than the length of this
   * string, it has the same effect as if it were equal to the length of
   * this string: <code>-1</code> is returned.
   *
   * @param   ch          a character.
   * @param   fromIndex   the index to start the search from.
   * @return  the index of the first occurrence of the character in the
   *          character sequence represented by this object that is greater
   *          than or equal to <code>fromIndex</code>, or <code>-1</code>
   *          if the character does not occur.
   */
  public int indexOf(int ch, int fromIndex)
  {

    int max = m_start + m_length;
    FastStringBuffer fsb = fsb();

    if (fromIndex < 0)
    {
      fromIndex = 0;
    }
    else if (fromIndex >= m_length)
    {

      // Note: fromIndex might be near -1>>>1.
      return -1;
    }

    for (int i = m_start + fromIndex; i < max; i++)
    {
      if (fsb.charAt(i) == ch)
      {
        return i - m_start;
      }
    }

    return -1;
  }

  /**
   * Returns a new string that is a substring of this string. The
   * substring begins with the character at the specified index and
   * extends to the end of this string. <p>
   * Examples:
   * <blockquote><pre>
   * "unhappy".substring(2) returns "happy"
   * "Harbison".substring(3) returns "bison"
   * "emptiness".substring(9) returns "" (an empty string)
   * </pre></blockquote>
   *
   * @param      beginIndex   the beginning index, inclusive.
   * @return     the specified substring.
   * @exception  IndexOutOfBoundsException  if
   *             <code>beginIndex</code> is negative or larger than the
   *             length of this <code>String</code> object.
   */
  public XMLString substring(int beginIndex)
  {

    int len = m_length - beginIndex;

    if (len <= 0)
      return XString.EMPTYSTRING;
    else
    {
      int start = m_start + beginIndex;

      return new XStringForFSB(fsb(), start, len);
    }
  }

  /**
   * Returns a new string that is a substring of this string. The
   * substring begins at the specified <code>beginIndex</code> and
   * extends to the character at index <code>endIndex - 1</code>.
   * Thus the length of the substring is <code>endIndex-beginIndex</code>.
   *
   * @param      beginIndex   the beginning index, inclusive.
   * @param      endIndex     the ending index, exclusive.
   * @return     the specified substring.
   * @exception  IndexOutOfBoundsException  if the
   *             <code>beginIndex</code> is negative, or
   *             <code>endIndex</code> is larger than the length of
   *             this <code>String</code> object, or
   *             <code>beginIndex</code> is larger than
   *             <code>endIndex</code>.
   */
  public XMLString substring(int beginIndex, int endIndex)
  {

    int len = endIndex - beginIndex;

    if (len > m_length)
      len = m_length;

    if (len <= 0)
      return XString.EMPTYSTRING;
    else
    {
      int start = m_start + beginIndex;

      return new XStringForFSB(fsb(), start, len);
    }
  }

  /**
   * Concatenates the specified string to the end of this string.
   *
   * @param   str   the <code>String</code> that is concatenated to the end
   *                of this <code>String</code>.
   * @return  a string that represents the concatenation of this object's
   *          characters followed by the string argument's characters.
   * @exception java.lang.NullPointerException if <code>str</code> is
   *          <code>null</code>.
   */
  public XMLString concat(String str)
  {

    // %OPT% Make an FSB here?
    return new XString(str().concat(str));
  }

  /**
   * Removes white space from both ends of this string.
   *
   * @return  this string, with white space removed from the front and end.
   */
  public XMLString trim()
  {
    return fixWhiteSpace(true, true, false);
  }

  /**
   * Returns whether the specified <var>ch</var> conforms to the XML 1.0 definition
   * of whitespace.  Refer to <A href="http://www.w3.org/TR/1998/REC-xml-19980210#NT-S">
   * the definition of <CODE>S</CODE></A> for details.
   * @param   ch      Character to check as XML whitespace.
   * @return          =true if <var>ch</var> is XML whitespace; otherwise =false.
   */
  private static boolean isSpace(char ch)
  {
    return XMLCharacterRecognizer.isWhiteSpace(ch);  // Take the easy way out for now.
  }

  /**
   * Conditionally trim all leading and trailing whitespace in the specified String.
   * All strings of white space are
   * replaced by a single space character (#x20), except spaces after punctuation which
   * receive double spaces if doublePunctuationSpaces is true.
   * This function may be useful to a formatter, but to get first class
   * results, the formatter should probably do it's own white space handling
   * based on the semantics of the formatting object.
   *
   * @param   trimHead    Trim leading whitespace?
   * @param   trimTail    Trim trailing whitespace?
   * @param   doublePunctuationSpaces    Use double spaces for punctuation?
   * @return              The trimmed string.
   */
  public XMLString fixWhiteSpace(boolean trimHead, boolean trimTail,
                                 boolean doublePunctuationSpaces)
  {

    int end = m_length + m_start;
    char[] buf = new char[m_length];
    FastStringBuffer fsb = fsb();
    boolean edit = false;

    /* replace S to ' '. and ' '+ -> single ' '. */
    int d = 0;
    boolean pres = false;

    for (int s = m_start; s < end; s++)
    {
      char c = fsb.charAt(s);

      if (isSpace(c))
      {
        if (!pres)
        {
          if (' ' != c)
          {
            edit = true;
          }

          buf[d++] = ' ';

          if (doublePunctuationSpaces && (d != 0))
          {
            char prevChar = buf[d - 1];

            if (!((prevChar == '.') || (prevChar == '!')
                  || (prevChar == '?')))
            {
              pres = true;
            }
          }
          else
          {
            pres = true;
          }
        }
        else
        {
          edit = true;
          pres = true;
        }
      }
      else
      {
        buf[d++] = c;
        pres = false;
      }
    }

    if (trimTail && 1 <= d && ' ' == buf[d - 1])
    {
      edit = true;

      d--;
    }

    int start = 0;

    if (trimHead && 0 < d && ' ' == buf[0])
    {
      edit = true;

      start++;
    }

    XMLStringFactory xsf = XMLStringFactoryImpl.getFactory();

    return edit ? xsf.newstr(buf, start, d - start) : this;
  }

  /**
   * Convert a string to a double -- Allowed input is in fixed
   * notation ddd.fff.
   *
   * %OPT% CHECK PERFORMANCE against generating a Java String and
   * converting it to double. The advantage of running in native
   * machine code -- perhaps even microcode, on some systems -- may
   * more than make up for the cost of allocating and discarding the
   * additional object. We need to benchmark this. 
   *
   * %OPT% More importantly, we need to decide whether we _care_ about
   * the performance of this operation. Does XString.toDouble constitute
   * any measurable percentage of our typical runtime? I suspect not!
   *
   * @return A double value representation of the string, or return Double.NaN 
   * if the string can not be converted.  */
  public double toDouble()
  {
    int end = m_length+m_start;
    if(0 == end)
      return Double.NaN;

    int start = m_start;
    FastStringBuffer fsb = fsb();
      
    long longResult=0;
    boolean isNegative=false;
    boolean trailingSpace=false;
    int[] digitsFound={0,0}; // intpart,fracpart
    int digitType=0;    // Index to which kind of digit we're accumulating
    double doubleResult;
    
    // Scan past leading whitespace characters
    while(start< end &&
          XMLCharacterRecognizer.isWhiteSpace( fsb.charAt(start) )
          )
      ++start;
    
    if (start < end && fsb.charAt(start) == '-')
    {
      isNegative=true;
      start++;
    }
    
    // parse the string from left to right converting as an integer.
    for (int i = start; i < end; i++)
    {
      char c = fsb.charAt(i);

      if(XMLCharacterRecognizer.isWhiteSpace(c))
      {
				trailingSpace=true;
        break;                  // Trailing whitespace is ignored
      }
      else if(trailingSpace)
	return Double.NaN;	// Nonspace after space is poorly formed
	
      switch(c)
      {
      case '.':
        if(digitType==0)
          digitType=1;
        else
          return Double.NaN;    // Second period is error
	break;
	
      case '0':			// NOT Unicode isDigit();  ASCII digits _only_
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
        longResult = longResult * 10 + (c - '0'); // Accumulate as int
        ++digitsFound[digitType]; // Remember scaling
	break;

      default:
        return Double.NaN;      // Nonnumeric is error
      }
    }

    if(0 ==digitsFound[0]&& 0==digitsFound[1])
      return Double.NaN;

    // Convert from scaled integer to floating point. This will come close. 
    // There's an alternative solution involving Double.longBitsToDouble
    // followed by a combined renormalize/scale operation... but I honestly
    // think the more straightforward solution comes out to just about
    // the same thing.
                
    long scale=1;               // AFAIK, java doesn't have an easier 10^n operation
    for(int i=digitsFound[1];i>0;--i) 
      scale*=10;
                
    doubleResult=((double)longResult)/scale;
                
    if(isNegative)
      doubleResult *= -1;
    return doubleResult;
  }

}