comparatorreverser.java

Java数据结构开发包

/*
  Copyright (c) 1999, 2000 Brown University, Providence, RI
  
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  copyright notice and this permission notice appear in supporting
  documentation, and that the name of Brown University not be used in
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  without specific, written prior permission.
  
  BROWN UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
  SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
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  PERFORMANCE OF THIS SOFTWARE.
*/

package jdsl.core.ref;

import jdsl.core.api.Comparator;



/**
 * Takes a <code>Comparator</code> and reverses the
 * ordering with respect to which the elements are compared.
 *
 * @author Don Blaheta (dpb)
 * @author Luca Vismara (lv)
 * @version JDSL 2.1.1 
 */
public class ComparatorReverser extends AbstractComparator
  implements Comparator {

  // instance variables
  
  private Comparator cmp_;


  // constructors
  
  /**
   * @param cmp The comparator to be reversed.
   */
  public ComparatorReverser (Comparator cmp) {
    cmp_ = cmp;
  }


  // instance methods from jdsl.core.api.Comparator

  /**
   * @return the negation of a <code>compare(Object,Object)</code>
   * call to the slave comparator; so if the other comparator
   * guarantees some number with an absolute value greater than one,
   * that value will be preserved
   */
  public int compare (Object a, Object b) {
    return -cmp_.compare(a,b);
  }
  
  public boolean isComparable (Object obj) {
    return cmp_.isComparable(obj);
  }

}