content: /*
   *    This program is free software; you can redistribute it and/or modify
   *    it under the terms of the GNU General Public License as published by
   *    the Free Software Foundation; either version 2 of the License, or
   *    (at your option) any later version.
   *
   *    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., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  /*
   *    Rule.java
   *    Copyright (C) 2001 University of Waikato, Hamilton, New Zealand
   */
  
  package weka.classifiers.rules;
  
  import weka.core.Copyable;
  import weka.core.Instance;
  import weka.core.Instances;
  import weka.core.RevisionHandler;
  import weka.core.WeightedInstancesHandler;
  
  import java.io.Serializable;
  
  /**
   * Abstract class of generic rule
   *
   * @author Xin Xu (xx5@cs.waikato.ac.nz)
   * @version $Revision: 1.8 $
   */
  public abstract class Rule 
      implements WeightedInstancesHandler, Copyable, Serializable, RevisionHandler {
  
      /** for serialization */
      private static final long serialVersionUID = 8815687740470471229L;
      
      /**
       * Get a shallow copy of this rule
       *
       * @return the copy
       */
      public Object copy(){ return this;}
      
      /**
       * Whether the instance covered by this rule
       * 
       * @param datum the instance in question
       * @return the boolean value indicating whether the instance 
       *         is covered by this rule
       */
      public abstract boolean covers(Instance datum);
  
      /**
       * Build this rule
       *
       * @param data the data used to build the rule
       * @exception Exception if rule cannot be built
       */    
      public abstract void grow(Instances data) throws Exception;    
  
      /**
       * Whether this rule has antecedents, i.e. whether it is a default rule
       * 
       * @return the boolean value indicating whether the rule has antecedents
       */
      public abstract boolean hasAntds();   
  
      /** 
       * Get the consequent of this rule, i.e. the predicted class 
       * 
       * @return the consequent
       */
      public abstract double getConsequent(); 
  
      /** 
       * The size of the rule.  Could be number of antecedents in the case
       * of conjunctive rule
       *
       * @return the size of the rule
       */
      public abstract double size(); 
  }
  