charset.java

java语法解释器生成器

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * JFlex 1.4.2                                                             *
 * Copyright (C) 1998-2008  Gerwin Klein <[e-mail]>                    *
 * All rights reserved.                                                    *
 *                                                                         *
 * This program is free software; you can redistribute it and/or modify    *
 * it under the terms of the GNU General Public License. See the file      *
 * COPYRIGHT for more information.                                         *
 *                                                                         *
 * This program is distributed in the hope that it will be useful,         *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of          *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           *
 * GNU General Public License for more details.                            *
 *                                                                         *
 * You should have received a copy of the GNU General Public License along *
 * with this program; if not, write to the Free Software Foundation, Inc., *
 * 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA                 *
 *                                                                         *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

package JFlex;


/**
 * 
 * @author Gerwin Klein 
 * @version JFlex 1.4.2, $Revision: 358 $, $Date: 2008-05-27 16:28:29 +1000 (Tue, 27 May 2008) $ 
 */
public final class CharSet {

  final static int BITS = 6;           // the number of bits to shift (2^6 = 64)
  final static int MOD = (1<<BITS)-1;  // modulus
  
  long bits[];

  private int numElements;
  
  
  public CharSet() {
    bits = new long[1];
  }


  public CharSet(int initialSize, int character) {
    bits = new long[(initialSize >> BITS)+1];
    add(character);
  }


  public void add(int character) {
    resize(character);

    if ( (bits[character >> BITS] & (1L << (character & MOD))) == 0) numElements++;

    bits[character >> BITS] |= (1L << (character & MOD));    
  }


  private int nbits2size (int nbits) {
    return ((nbits >> BITS) + 1);
  }


  private void resize(int nbits) {
    int needed = nbits2size(nbits);

    if (needed < bits.length) return;
         
    long newbits[] = new long[Math.max(bits.length*2,needed)];
    System.arraycopy(bits, 0, newbits, 0, bits.length);
    
    bits = newbits;
  }


  public boolean isElement(int character) {
    int index = character >> BITS;
    if (index >= bits.length)  return false;
    return (bits[index] & (1L << (character & MOD))) != 0;
  }


  public CharSetEnumerator characters() {
    return new CharSetEnumerator(this);
  }


  public boolean containsElements() {
    return numElements > 0;
  }

  public int size() {
    return numElements;
  }
  
  public String toString() {
    CharSetEnumerator set = characters();

    StringBuffer result = new StringBuffer("{");

    if ( set.hasMoreElements() ) result.append(""+set.nextElement());

    while ( set.hasMoreElements() ) {
      int i = set.nextElement();
      result.append( ", "+i);
    }

    result.append("}");

    return result.toString();
  }
}