001/**
002 * Logback: the reliable, generic, fast and flexible logging framework.
003 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
004 *
005 * This program and the accompanying materials are dual-licensed under
006 * either the terms of the Eclipse Public License v1.0 as published by
007 * the Eclipse Foundation
008 *
009 *   or (per the licensee's choosing)
010 *
011 * under the terms of the GNU Lesser General Public License version 2.1
012 * as published by the Free Software Foundation.
013 */
014package ch.qos.logback.core.boolex;
015
016import java.util.ArrayList;
017import java.util.List;
018
019import org.codehaus.janino.ScriptEvaluator;
020
021/**
022 * Abstract class which sets the groundwork for janino based evaluations.
023 * 
024 * @author Ceki Gülcü
025 * 
026 * @param <E> event type
027 */
028abstract public class JaninoEventEvaluatorBase<E> extends EventEvaluatorBase<E> {
029
030    static Class<?> EXPRESSION_TYPE = boolean.class;
031    static Class<?>[] THROWN_EXCEPTIONS = new Class[1];
032
033    static public final int ERROR_THRESHOLD = 4;
034    static {
035        THROWN_EXCEPTIONS[0] = EvaluationException.class;
036    }
037
038    private String expression;
039
040    ScriptEvaluator scriptEvaluator;
041    private int errorCount = 0;
042
043    abstract protected String getDecoratedExpression();
044
045    abstract protected String[] getParameterNames();
046
047    abstract protected Class<?>[] getParameterTypes();
048
049    abstract protected Object[] getParameterValues(E event);
050
051    protected List<Matcher> matcherList = new ArrayList<>();
052
053    @Override
054    public void start() {
055        try {
056            assert context != null;
057            scriptEvaluator = new ScriptEvaluator(getDecoratedExpression(), EXPRESSION_TYPE, getParameterNames(),
058                    getParameterTypes(), THROWN_EXCEPTIONS);
059            super.start();
060        } catch (Exception e) {
061            addError("Could not start evaluator with expression [" + expression + "]", e);
062        }
063    }
064
065    public boolean evaluate(E event) throws EvaluationException {
066        if (!isStarted()) {
067            throw new IllegalStateException("Evaluator [" + name + "] was called in stopped state");
068        }
069        try {
070            Boolean result = (Boolean) scriptEvaluator.evaluate(getParameterValues(event));
071            return result;
072        } catch (Exception ex) {
073            errorCount++;
074            if (errorCount >= ERROR_THRESHOLD) {
075                stop();
076            }
077            throw new EvaluationException("Evaluator [" + name + "] caused an exception", ex);
078        }
079    }
080
081    public String getExpression() {
082        return expression;
083    }
084
085    public void setExpression(String expression) {
086        this.expression = expression;
087    }
088
089    public void addMatcher(Matcher matcher) {
090        matcherList.add(matcher);
091    }
092
093    public List<Matcher> getMatcherList() {
094        return matcherList;
095    }
096}