1 /**
2 * Logback: the reliable, generic, fast and flexible logging framework.
3 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
4 *
5 * This program and the accompanying materials are dual-licensed under
6 * either the terms of the Eclipse Public License v1.0 as published by
7 * the Eclipse Foundation
8 *
9 * or (per the licensee's choosing)
10 *
11 * under the terms of the GNU Lesser General Public License version 2.1
12 * as published by the Free Software Foundation.
13 */
14 package ch.qos.logback.core.filter;
15
16 import ch.qos.logback.core.boolex.EvaluationException;
17 import ch.qos.logback.core.boolex.EventEvaluator;
18 import ch.qos.logback.core.spi.FilterReply;
19
20 /**
21 * The value of the {@link #onMatch} and {@link #onMismatch} attributes is set
22 * to {@link FilterReply#NEUTRAL}, so that a badly configured evaluator filter
23 * does not disturb the functioning of the filter chain.
24 *
25 * <p>
26 * It is expected that one of the two attributes will have its value changed to
27 * {@link FilterReply#ACCEPT} or {@link FilterReply#DENY}. That way, it is
28 * possible to decide if a given result must be returned after the evaluation
29 * either failed or succeeded.
30 *
31 *
32 * <p>
33 * For more information about filters, please refer to the online manual at
34 * http://logback.qos.ch/manual/filters.html
35 *
36 * @author Ceki Gülcü
37 * @author Sébastien Pennec
38 */
39 public class EvaluatorFilter<E> extends AbstractMatcherFilter<E> {
40
41 EventEvaluator<E> evaluator;
42
43 @Override
44 public void start() {
45 if (evaluator != null) {
46 super.start();
47 } else {
48 addError("No evaluator set for filter " + this.getName());
49 }
50 }
51
52 public EventEvaluator<E> getEvaluator() {
53 return evaluator;
54 }
55
56 public void setEvaluator(EventEvaluator<E> evaluator) {
57 this.evaluator = evaluator;
58 }
59
60 public FilterReply decide(E event) {
61 // let us not throw an exception
62 // see also bug #17.
63 if (!isStarted() || !evaluator.isStarted()) {
64 return FilterReply.NEUTRAL;
65 }
66 try {
67 if (evaluator.evaluate(event)) {
68 return onMatch;
69 } else {
70 return onMismatch;
71 }
72 } catch (EvaluationException e) {
73 addError("Evaluator " + evaluator.getName() + " threw an exception", e);
74 return FilterReply.NEUTRAL;
75 }
76 }
77
78 }