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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.log4j.rule;
19  
20  import org.apache.log4j.spi.LoggingEvent;
21  
22  import java.util.Stack;
23  
24  /***
25   * A Rule class implementing logical not.
26   *
27   * @author Scott Deboy (sdeboy@apache.org)
28   */
29  public class NotRule extends AbstractRule {
30      /***
31       * Serialization ID.
32       */
33    static final long serialVersionUID = -6827159473117969306L;
34      /***
35       * Enclosed rule.
36       */
37    private final Rule rule;
38  
39      /***
40       * Create new instance.
41       * @param rule enclosed rule.
42       */
43    private NotRule(final Rule rule) {
44      super();
45      this.rule = rule;
46    }
47  
48      /***
49       * Create new instance.
50       * @param rule enclosed rule.
51       * @return new rule.
52       */
53    public static Rule getRule(final Rule rule) {
54        return new NotRule(rule);
55    }
56  
57      /***
58       * Create new instance from top element of stack.
59       * @param stack stack
60       * @return new rule.
61       */
62    public static Rule getRule(final Stack stack) {
63        if (stack.size() < 1) {
64            throw new IllegalArgumentException(
65                    "Invalid NOT rule - expected one rule but received "
66                            + stack.size());
67        }
68        Object o1 = stack.pop();
69        if (o1 instanceof Rule) {
70          Rule p1 = (Rule) o1;
71          return new NotRule(p1);
72        }
73        throw new IllegalArgumentException(
74                "Invalid NOT rule: - expected rule but received " + o1);
75    }
76  
77      /*** {@inheritDoc} */
78    public boolean evaluate(final LoggingEvent event) {
79      return !(rule.evaluate(event));
80    }
81  }