stringutils.java

The program is used for the calculations of the day , week , month on the calendar .

package us.k5n.ical;

import java.util.Vector;


/**
  * iCal StringFormatter utility class
  * @version $Id$
  * @author Craig Knudsen, [e-mail]
  */
public class StringUtils
  implements Constants
{

  /**
    * Format a string into ical folded-line format (which states
    * that lines should not be longer than 75 characters, excluding
    * the line break.)
    * @param x	The input string to be formatted
    * @return	The properly formatted string (includes newline)
    */
  static public String foldLine ( String x )
  {
    int len = 0;
    StringBuffer ret = new StringBuffer ( x.length() );
    for ( int i = 0; i < x.length(); i++ ) {
      if ( len >= MAX_LINE_LENGTH - 1 ) {
        ret.append ( CRLF );
        ret.append ( ' ' );
        len = 0;
      }
      if ( x.charAt ( i ) == CR ) {
        // Ignore
      } else if ( x.charAt ( i ) == LF ) {
        ret.append ( "\\n" );
        len += 2;
      } else {
        ret.append ( x.charAt ( i ) );
        len++;
      }
    }
    String r = ret.toString ();
    if ( ! r.endsWith ( CRLF ) )
      r += CRLF;
    return r;
  }

  /**
    * Unfold a multi-line iCal String into a single line.
    * New line escape sequences will be converted back to
    * CRLF (015 012).  Rather than throwing an ParseException
    * when lines longer than 75 characters are encountered, the
    * error will be ignored for greater compatibility.
    * Additionally, non-ASCII characters will be converted from
    * their quoted-printable format.
    * @param line	Input iCal line
    * @return		The "unfolded" line
    * @see foldLine
    */
  static public String unfoldLine ( String line )
    throws ParseException
  {
    return unfoldLine ( line, PARSE_LOOSE );
  }

  /**
    * Unfold a multi-line iCal String into a single line.
    * New line escape sequences will be converted back to
    * CRLF (015 012).
    * If a line is longer than 75 characters, a ParseException will
    * be generated if parseMode is set to PARSE_STRICT.
    * Additionally, non-ASCII characters will be converted from
    * their quoted-printable format.
    * If parseMode is not set to PARSE_STRICT, escaped commas "\," will
    * be unescaped.  (Mozilla Sunbird does this escaping which is not
    * part of the RFC 2445 specification.)
    * @param line	Input iCal line
    * @param parseMode	PARSE_STRICT or PARSE_LOOSE; PARSE_STRICT will
    *			generate an exception on lines too long.
    * @return		The "unfolded" line
    * @see foldLine
    */
  // TODO: convert quotable-printable format
  static public String unfoldLine ( String line, int parseMode )
    throws ParseException
  {
    int len = 0;
    StringBuffer ret = new StringBuffer ( line.length() );
    for ( int i = 0; i < line.length(); i++ ) {
      // check line length
      if ( len > MAX_LINE_LENGTH ) {
        if ( parseMode == PARSE_STRICT ) {
          throw new ParseException ( "Found line longer than " +
            MAX_LINE_LENGTH + " limit", line );
        }
      }
      char ch = line.charAt ( i );
      char ch2 = ( i + 1 < line.length() ? line.charAt ( i + 1 ) : 0 );
      char ch3 = ( i + 2 < line.length() ? line.charAt ( i + 2 ) : 0 );
      if ( ch == '\\' && ch2 == 'n' && ch == '=' && parseMode == PARSE_LOOSE ) {
        // Convert "\\\n=" into CRLF
        // This is another Mozilla Sunbird hack
        ret.append ( CRLF );
        i++;
        len = 0;
      } if ( ch == '\\' && ch2 == 'n' ) {
        // Convert "\\\n" into CRLF
        ret.append ( CRLF );
        i++;
        len = 0;
      } else if ( ch == LF && ( ch2 == SPACE || ch2 == TAB ) ) {
        // unfold this...
        i++;
      } else if ( ch == '\\' && ch2 == ',' && parseMode == PARSE_LOOSE ) {
        // this is Mozilla's incorrect way of handling commas :-(
        ret.append ( ',' );
        i++;
      } else if ( ch == LF && ch2 == 0 ) {
        // end of data
      } else if ( ch == LF ) {
        // This should be a parse error.  We should always find either
        // a space/tab after LF (folding) or it should be the end of
        // the data line.
        if ( parseMode == PARSE_STRICT ) {
          throw new ParseException ( "Invalid line termination at char " +
            i, line );
        } else {
          // Oh, well... ignore it. Assume they forgot the space that
          // starts the next line.
        }
      } else if ( ch == CR ) {
        // ignore CR.  Should be a LF next.
      } else if ( ch == '\\' && ch2 == 'r' ) {
        // ignore CR.  Should be a LF next.
      } else {
        ret.append ( ch );
        len++;
      }
    }
    return ret.toString ();
  }

  /**
    * Determine if a String is a whole number
    */
  static public boolean isNumber ( String str, boolean allowSign )
  {
    int i = 0;
    if ( str.length() == 0 )
      return false;

    if ( str.charAt ( 0 ) == '+' || str.charAt ( 0 ) == '-' )
      i = 1;
    for ( ; i < str.length(); i++ ) {
      if ( str.charAt ( 0 ) <= '0' || str.charAt ( 0 ) >= '9' )
        return false;
    }
    return true;
  }

  /**
    * Determine if a String is a whole number
    */
  static public boolean isNumber ( String str )
  {
    return isNumber ( str, false );
  }
}