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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.logging.log4j.core;
19  
20  import org.apache.logging.log4j.Level;
21  import org.apache.logging.log4j.Marker;
22  import org.apache.logging.log4j.message.Message;
23  import org.apache.logging.log4j.util.EnglishEnums;
24  
25  /**
26   * Interface that must be implemented to allow custom event filtering. It is highly recommended that
27   * applications make use of the Filters provided with this implementation before creating their own.
28   *
29   * This interface supports "global" filters (i.e. - all events must pass through them first), attached to
30   * specific loggers and associated with Appenders. It is recommended that, where possible, Filter implementations
31   * create a generic filtering method that can be called from any of the filter methods.
32   */
33  public interface Filter {
34  
35      /**
36       * The result that can returned from a filter method call.
37       */
38       enum Result {
39          /**
40           * The event will be processed without further filtering based on the log Level.
41           */
42          ACCEPT,
43          /**
44           * No decision could be made, further filtering should occur.
45           */
46          NEUTRAL,
47          /**
48           * The event should not be processed.
49           */
50          DENY;
51  
52          /**
53           * Returns the Result for the given string.
54           *
55           * @param name The Result enum name, case-insensitive. If null, returns, null
56           * @return a Result enum value or null if name is null
57           */
58          public static Result toResult(final String name) {
59              return toResult(name, null);
60          }
61  
62          /**
63           * Returns the Result for the given string.
64           *
65           * @param name The Result enum name, case-insensitive. If null, returns, defaultResult
66           * @param defaultResult the Result to return if name is null
67           * @return a Result enum value or null if name is null
68           */
69          public static Result toResult(final String name, final Result defaultResult) {
70              return EnglishEnums.valueOf(Result.class, name, defaultResult);
71          }
72  }
73  
74      /**
75       * Returns the result that should be returned when the filter does not match the event.
76       * @return the Result that should be returned when the filter does not match the event.
77       */
78      Result getOnMismatch();
79      /**
80       * Returns the result that should be returned when the filter matches the event.
81       * @return the Result that should be returned when the filter matches the event.
82       */
83      Result getOnMatch();
84  
85      /**
86       * Filter an event.
87       * @param logger The Logger.
88       * @param level The event logging Level.
89       * @param marker The Marker for the event or null.
90       * @param msg String text to filter on.
91       * @param params An array of parameters or null.
92       * @return the Result.
93       */
94      Result filter(Logger logger, Level level, Marker marker, String msg, Object... params);
95  
96      /**
97       * Filter an event.
98       * @param logger The Logger.
99       * @param level The event logging Level.
100      * @param marker The Marker for the event or null.
101      * @param msg Any Object.
102      * @param t A Throwable or null.
103      * @return the Result.
104      */
105     Result filter(Logger logger, Level level, Marker marker, Object msg, Throwable t);
106 
107     /**
108      * Filter an event.
109      * @param logger The Logger.
110      * @param level The event logging Level.
111      * @param marker The Marker for the event or null.
112      * @param msg The Message
113      * @param t A Throwable or null.
114      * @return the Result.
115      */
116     Result filter(Logger logger, Level level, Marker marker, Message msg, Throwable t);
117 
118     /**
119      * Filter an event.
120      * @param event The Event to filter on.
121      * @return the Result.
122      */
123     Result filter(LogEvent event);
124 
125 }