numberedpredicate.java

SHOP2 一个人工智能里面关于任务分解和任务规划的系统。JSHOP2是其java版本。

package JSHOP2;

/** This class represents a predicate with an integer number associated with
 *  it. It serves two different purposes: First, to represent a protection on
 *  some predicate (the integer number being the number of times the predicate
 *  is protected), and second, when a predicate is deleted from the current
 *  state of the world, an object of this class represents the deleted
 *  predicate and where it was deleted from so that in case of a backtrack the
 *  deleted predicate can be added back exactly where it was before.
 *
 *  @author Okhtay Ilghami
 *  @author <a href="http://www.cs.umd.edu/~okhtay">http://www.cs.umd.edu/~okhtay</a>
 *  @version 1.0.3
*/
public class NumberedPredicate
{
  /** The integer.
  */
  private int number;

  /** The predicate.
  */
  private Predicate pre;

  /** To initialize an object of this class. The integer will be set to 1.
   *
   *  @param preIn
   *          the predicate.
  */
  public NumberedPredicate(Predicate preIn)
  {
    pre = preIn;
    number = 1;
  }

  /** To initialize an object of this class.
   *
   *  @param preIn
   *          the predicate.
   *  @param numberIn
   *          the integer.
  */
  public NumberedPredicate(Predicate preIn, int numberIn)
  {
    pre = preIn;
    number = numberIn;
  }

  /** To decrease the integer by one. This is used when a protection is
   *  deleted.
   *
   *  @return
   *          <code>false</code> if the integer become zero, <code>true</code>
   *          otherwise.
  */
  public boolean dec()
  {
    if (number > 1)
    {
      number--;
      return true;
    }
    else
      return false;
  }

  /** To get the head of the predicate.
   *
   *  @return
   *          the head of the predicate.
  */
  public int getHead()
  {
    return pre.getHead();
  }

  /** To get the integer associated with this object.
   *
   *  @return
   *          the integer associated with this object.
  */
  public int getNumber()
  {
    return number;
  }

  /** To get the parameters of the predicate.
   *
   *  @return
   *          the parameters of the predicate.
  */
  public Term getParam()
  {
    return pre.getParam();
  }

  /** To increase the integer by one. This is used when a protection is added.
  */
  public void inc()
  {
    number++;
  }

  public String toString() {
    return pre.toString();
  }
}