// Copyright 1999 MageLang Institute
// <version>$Id: //depot/main/src/edu/modules/Collections/magercises/BitSet/Solution/SparseBitSet.java#2 $</version>
import java.util.*;

public class SparseBitSet extends BitSet {

  protected Set bitset;

  protected Set getBitSet() {
    return bitset;
  }

  // Replace BitSet no-arg constructor
  public SparseBitSet() {
    bitset = new HashSet();
  }

  // Performs a logical AND of this target bit set 
  // with the argument bit set
  public void and(SparseBitSet set) {
    bitset.retainAll(set.getBitSet());
  }

  // Clears all of the bits in this bit set whose 
  // corresponding bit is set in the specified bit set
  public void andNot(SparseBitSet set) {
    bitset.removeAll(set.getBitSet());
  }

  // Removes the bit specified from the set
  public void clear(int bit) {
    bitset.remove(new Integer(bit));
  }

  // Clone
  public Object clone() {
    SparseBitSet set = new SparseBitSet();
    set.or(this);
    return set;
  }

  // Equality check
  public boolean equals(Object obj) {
    if (obj == this) return true;
    if (!(obj instanceof SparseBitSet)) {
      return false;
    } else {
      SparseBitSet other = (SparseBitSet)obj;
      return bitset.equals(other.getBitSet());
    }
  }

  // Checks if specific bit contained in set
  public boolean get(int bit) {
    return bitset.contains(new Integer (bit));
  }

  // Return internal set hashcode
  public int hashCode() {
    return bitset.hashCode();
  }

  // Returns the maximum element in set + 1
  public int length() {
    int returnValue = 0;
    // Make sure set not empty
    // Get maximum value +1
    if (bitset.size() > 0) {
      Integer max = (Integer)Collections.max(bitset);
      returnValue = max.intValue()+1;
    }
    return returnValue;
  }

  // Performs a logical OR of this bit set 
  // with the bit set argument
  public void or(SparseBitSet set) {
    bitset.addAll(set.getBitSet());
  }

  // Adds bit specified to set
  public void set(int bit) {
    bitset.add(new Integer (bit));
  }

  // Return size of internal set
  public int size() {
    return bitset.size();
  }

  // Return string representation of internal set
  public String toString() {
    return bitset.toString();
  }

  // Performs a logical XOR of this bit set 
  // with the bit set argument
  public void xor(SparseBitSet set) {
    Set thisSet = new HashSet(bitset);
    Set thatSet = new HashSet(set.getBitSet());
    // Find out what elements are in this set
    // but not in the other set
    thisSet.removeAll(thatSet);
    // Find out what elements are in the other set
    // but not in this set
    thatSet.removeAll(bitset);
    // Combine sets
    bitset.retainAll(thisSet);
    bitset.addAll(thatSet);
  }
}