package dlib;

/*
$Id: SmallSet.java 1.2 1996/09/10 02:03:30 ddyer Exp $
$Log: SmallSet.java $
Revision 1.2  1996/09/10 02:03:30  ddyer
added list

Revision 1.1  1996/09/07 13:06:00  ddyer
Initial revision

*/

/**

Implements a "small set" which maps an array of strings into an integer of bits,
and prints itself in an intellegible way (instead of as an unintellegible integer).

@author Dave Dyer <ddyer@netcom.com>
@version 1.0, August 1996
*/


public abstract class SmallSet extends BaseObject
{ 
	public int value;
  public abstract String[] Elements();
  /* constructors */
  public SmallSet() {value=0;}
  public SmallSet(int val) { value = val; }
	
	public int Set_Indexof(String element)
	{String Elements[] = Elements();
	 for(int i=0;  i<Elements.length;  i++) 
	  { if(element.equals(Elements[i])) { return(1<<i); };
	  }
	 throw new Error("Element " + element + "is not in " + getName());
	}
	public boolean equals(SmallSet other)
	{	return((value==other.value) && (getClass()==other.getClass()));
	}
  public void Add_Element(String element)
  { value |= Set_Indexof(element);
  }
  public void Remove_Element(String element)
  { value &= ~Set_Indexof(element);  
  }
  public boolean Contains_Element(String element)
  { return((value&Set_Indexof(element)) != 0);
  }
  public String getElements()
  { String val = "";
    String elements[]=Elements();
    for(int i=0; i<elements.length; i++) 
     { if( ((1<<i)&value)!=0) {val = val + " " + elements[i]; }
     }
    return(val);
  }

  public String toString () 
	{ return("#{set of " + this.getClass().getName() + ": " + this.getElements() + "}");
	}
    
}