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 java.util.Optional;
  import java.util.Stack;
  
  import org.apache.tools.ant.BuildException;
  import org.apache.tools.ant.Project;
  import org.apache.tools.ant.types.Resource;
  
  /**
   * Reverses another ResourceComparator.  If no nested ResourceComparator
   * is supplied, the compared Resources' natural order will be reversed.
   * @since Ant 1.7
   */
  public class Reverse extends ResourceComparator {
      private static final String ONE_NESTED
          = "You must not nest more than one ResourceComparator for reversal.";
  
      private ResourceComparator nested;
  
      /**
       * Default constructor.
       */
      public Reverse() {
      }
  
      /**
       * Construct a new Reverse, supplying the ResourceComparator to be reversed.
       * @param c the ResourceComparator to reverse.
       */
      public Reverse(ResourceComparator c) {
          add(c);
      }
  
      /**
       * Add the ResourceComparator to reverse.
       * @param c the ResourceComparator to add.
       */
      public void add(ResourceComparator c) {
          if (nested != null) {
              throw new BuildException(ONE_NESTED);
          }
          nested = c;
          setChecked(false);
      }
  
      /**
       * 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 greater than, equal to, or less than the second.
       */
      protected int resourceCompare(Resource foo, Resource bar) {
          return Optional.<Comparator<Resource>> ofNullable(nested)
              .orElseGet(Comparator::naturalOrder).reversed().compare(foo, bar);
      }
  
      protected void dieOnCircularReference(Stack<Object> stk, Project p)
          throws BuildException {
          if (isChecked()) {
              return;
          }
          if (isReference()) {
              super.dieOnCircularReference(stk, p);
          } else {
              if (nested != null) {
                  pushAndInvokeCircularReferenceCheck(nested, stk, p);
              }
              setChecked(true);
          }
      }
  
  }
  