cvs commit: jakarta-commons/collections/src/java/org/apache/commons/collections/comparators TransformingComparator.java

[js...@apache.org]

jstrachan    2002/06/07 23:42:00

  Added:       collections/src/java/org/apache/commons/collections/comparators
                        TransformingComparator.java
  Log:
  Added Jonathan Carlson's patch for a Comparator that uses a Transformer
  
  Revision  Changes    Path
  1.1                  jakarta-commons/collections/src/java/org/apache/commons/collections/comparators/TransformingComparator.java
  
  Index: TransformingComparator.java
  ===================================================================
  package org.apache.commons.collections.comparators;
  
  /* ====================================================================
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 2001 The Apache Software Foundation.  All rights
   * reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution,
   *    if any, must include the following acknowledgment:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowledgment may appear in the software itself,
   *    if and wherever such third-party acknowledgments normally appear.
   *
   * 4. The names "Apache" and "Apache Software Foundation" and
   *    "Apache Commons" must not be used to endorse or promote products
   *    derived from this software without prior written permission. For
   *    written permission, please contact apache@apache.org.
   *
   * 5. Products derived from this software may not be called "Apache",
   *    "Apache Turbine", nor may "Apache" appear in their name, without
   *    prior written permission of the Apache Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   */
  
  import java.util.Comparator;
  
  import org.apache.commons.collections.Transformer;
  
  /**
   * Decorates another Comparator with transformation behavior.&nbsp;That is, the
   * return value from the transform operation will be passed to the decorated
   * <CODE>Comparator#compare</CODE> method.
   * <p>
   * @see org.apache.commons.collections.Transformer
   * @see org.apache.commons.collections.comparators.ComparableComparator
   */
  public class TransformingComparator implements Comparator
  {
      protected Comparator decorated;
      protected Transformer transformer;
  
      /**
       * Constructs an instance with the given Transformer and a ComparableComparator.
       * @param transformer what will transform the instance.
       */
      public TransformingComparator(Transformer transformer)
      {
          this(transformer, new ComparableComparator());
      }
  
      /**
       * Constructs an instance with the given Transformer and Comparator
       * @param decorated  the decorated Comparator
       * @param getterName    the getter name
       */
      public TransformingComparator(Transformer transformer, Comparator decorated)
      {
          this.decorated = decorated;
          this.transformer = transformer;
      }
  
      /**
       * Returns the result of comparing the values from the transform operation.
       * @return the result of comparing the values from the transform operation
       */
      public int compare(Object o1, Object o2)
      {
          Object value1 = this.transformer.transform(o1);
          Object value2 = this.transformer.transform(o2);
          return this.decorated.compare(value1, value2);
      }
  
  }
  
  
  
  

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