content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one or more
   *  contributor license agreements.  See the NOTICE file distributed with
   *  this work for additional information regarding copyright ownership.
   *  The ASF licenses this file to You under the Apache License, Version 2.0
   *  (the "License"); you may not use this file except in compliance with
   *  the License.  You may obtain a copy of the License at
   *
   *      https://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   *
   */
  package org.apache.tools.ant.types.resources.comparators;
  
  import java.util.Comparator;
  
  import org.apache.tools.ant.types.DataType;
  import org.apache.tools.ant.types.Resource;
  
  /**
   * Abstract Resource Comparator.
   * @since Ant 1.7
   */
  public abstract class ResourceComparator extends DataType implements Comparator<Resource> {
  
      /**
       * Compare two objects.
       * @param foo the first Object.
       * @param bar the second Object.
       * @return a negative integer, zero, or a positive integer as the first
       *         argument is less than, equal to, or greater than the second.
       * @throws ClassCastException if either argument is null.
       */
      @Override
      public final int compare(Resource foo, Resource bar) {
          dieOnCircularReference();
          ResourceComparator c = isReference() ? getRef() : this;
          return c.resourceCompare(foo, bar);
      }
  
      /**
       * Test for equality with this ResourceComparator.
       * @param o the Object to compare against.
       * @return true if the specified Object equals this one.
       */
      @Override
      public boolean equals(Object o) {
          if (isReference()) {
              return getRef().equals(o);
          }
          return o != null && (o == this || o.getClass().equals(getClass()));
      }
  
      /**
       * Hashcode based on the rules for equality.
       * @return a hashcode.
       */
      @Override
      public synchronized int hashCode() {
          if (isReference()) {
              return getRef().hashCode();
          }
          return getClass().hashCode();
      }
  
      /**
       * Compare two Resources.
       * @param foo the first Resource.
       * @param bar the second Resource.
       * @return a negative integer, zero, or a positive integer as the first
       *         argument is less than, equal to, or greater than the second.
       */
      protected abstract int resourceCompare(Resource foo, Resource bar);
  
      private ResourceComparator getRef() {
          return getCheckedRef(ResourceComparator.class);
      }
  }
  