package cz.cuni.amis.utils;
   
   import java.util.Arrays;
   import java.util.Comparator;
   
   /**
    * N-Key used for maps.
    * <p><p>
    * Remember that all passed "commutatives" are flatted (but within the commutatives parts)!
   * <p><p>
   * NKeyCommutative can be equal to NKey and vice versa!
   *
   * @author jgemrot
   *
   */
  public class NKeyCommutative extends NKey {
  
  	@SuppressWarnings("unchecked")
  	private Comparator HASH_CODE_COMPARATOR = new Comparator() {
  
  		@Override
  		public int compare(Object arg0, Object arg1){
  			if (arg0 == null) {
  				if (arg1 == null) return 0;
  				return -1;
  			}
  			if (arg1 == null) return 1;
  			return arg0.hashCode() - arg1.hashCode();
  		}
  
  	};
  
  	public NKeyCommutative(Object[]... commutatives) {
  		if (commutatives.length == 1) {
  			Arrays.sort(commutatives[0], HASH_CODE_COMPARATOR);
  			init(commutatives[0]);
  		} else {
  			int length = 0;
  			for (Object[] c : commutatives) {
  				Arrays.sort(c, HASH_CODE_COMPARATOR);
  				length += c.length;
  			}
  			Object[] keys = new Object[length];
  			int index = 0;
  			for (Object[] c : commutatives) {
  				System.arraycopy(c, 0, keys, index, c.length);
  				index += c.length;
  			}
  			init(keys);
  		}
  	}
  
  }