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Java > Open Source Codes > org > apache > tools > ant > types > resources > comparators > Reverse


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  *
17  */
18 package org.apache.tools.ant.types.resources.comparators;
19
20 import org.apache.tools.ant.BuildException;
21 import org.apache.tools.ant.types.Resource;
22
23 /**
24  * Reverses another ResourceComparator. If no nested ResourceComparator
25  * is supplied, the compared Resources' natural order will be reversed.
26  * @since Ant 1.7
27  */
28 public class Reverse extends ResourceComparator {
29     private static final String JavaDoc ONE_NESTED
30         = "You must not nest more than one ResourceComparator for reversal.";
31
32     private ResourceComparator nested;
33
34     /**
35      * Default constructor.
36      */
37     public Reverse() {
38     }
39
40     /**
41      * Construct a new Reverse, supplying the ResourceComparator to be reversed.
42      * @param c the ResourceComparator to reverse.
43      */
44     public Reverse(ResourceComparator c) {
45         add(c);
46     }
47
48     /**
49      * Add the ResourceComparator to reverse.
50      * @param c the ResourceComparator to add.
51      */
52     public void add(ResourceComparator c) {
53         if (nested != null) {
54             throw new BuildException(ONE_NESTED);
55         }
56         nested = c;
57     }
58
59     /**
60      * Compare two Resources.
61      * @param foo the first Resource.
62      * @param bar the second Resource.
63      * @return a negative integer, zero, or a positive integer as the first
64      * argument is greater than, equal to, or less than the second.
65      */
66     protected int resourceCompare(Resource foo, Resource bar) {
67         return -1 * (nested == null
68             ? foo.compareTo(bar) : nested.compare(foo, bar));
69     }
70
71 }
72
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