/*
 *    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.
 */

/*
 *    WekaEnumeration.java
 *    Copyright (C) 2009 University of Waikato, Hamilton, New Zealand
 *
 */
package weka.core;

import java.util.Enumeration;
import java.util.List;
import weka.core.RevisionHandler;

/**
 * Class for enumerating an array list's elements.
 */
public class WekaEnumeration
  implements Enumeration, RevisionHandler {
  
  /** The counter. */
  private int m_Counter;
  // These JML commands say how m_Counter implements Enumeration
  //@ in moreElements;
  //@ private represents moreElements = m_Counter < m_Vector.size();
  //@ private invariant 0 <= m_Counter && m_Counter <= m_Vector.size();
  
  /** The vector. */
  private /*@non_null@*/ List m_Vector;
  
  /** Special element. Skipped during enumeration. */
  private int m_SpecialElement;
  //@ private invariant -1 <= m_SpecialElement;
  //@ private invariant m_SpecialElement < m_Vector.size();
  //@ private invariant m_SpecialElement>=0 ==> m_Counter!=m_SpecialElement;
  
  /**
   * Constructs an enumeration.
   *
   * @param vector the vector which is to be enumerated
   */
  public WekaEnumeration(/*@non_null@*/List vector) {
    
    m_Counter = 0;
    m_Vector = vector;
    m_SpecialElement = -1;
  }
  
  /**
   * Constructs an enumeration with a special element.
   * The special element is skipped during the enumeration.
   *
   * @param vector the vector which is to be enumerated
   * @param special the index of the special element
   */
  //@ requires 0 <= special && special < vector.size();
  public WekaEnumeration(/*@non_null@*/List vector, int special){
    
    m_Vector = vector;
    m_SpecialElement = special;
    if (special == 0) {
      m_Counter = 1;
    } else {
      m_Counter = 0;
    }
  }
  
  
  /**
   * Tests if there are any more elements to enumerate.
   *
   * @return true if there are some elements left
   */
  public final /*@pure@*/ boolean hasMoreElements() {
    
    if (m_Counter < m_Vector.size()) {
      return true;
    }
    return false;
  }
  
  /**
   * Returns the next element.
   *
   * @return the next element to be enumerated
   */
  //@ also requires hasMoreElements();
  public final Object nextElement() {
    
    Object result = m_Vector.get(m_Counter);
    
    m_Counter++;
    if (m_Counter == m_SpecialElement) {
      m_Counter++;
    }
    return result;
  }
  
  /**
   * Returns the revision string.
   * 
   * @return		the revision
   */
  public String getRevision() {
    return RevisionUtils.extract("$Revision: 5955 $");
  }
}