001/**
002 * Logback: the reliable, generic, fast and flexible logging framework.
003 * Copyright (C) 1999-2022, 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.model.processor.conditional;
015
016import ch.qos.logback.core.util.EnvUtil;
017import ch.qos.logback.core.util.OptionHelper;
018import ch.qos.logback.core.Context;
019import ch.qos.logback.core.CoreConstants;
020import ch.qos.logback.core.joran.conditional.Condition;
021import ch.qos.logback.core.joran.conditional.PropertyEvalScriptBuilder;
022import ch.qos.logback.core.model.Model;
023import ch.qos.logback.core.model.conditional.IfModel;
024import ch.qos.logback.core.model.conditional.IfModel.BranchState;
025import ch.qos.logback.core.model.processor.ModelHandlerBase;
026import ch.qos.logback.core.model.processor.ModelHandlerException;
027import ch.qos.logback.core.model.processor.ModelInterpretationContext;
028import ch.qos.logback.core.spi.ScanException;
029
030public class IfModelHandler extends ModelHandlerBase {
031
032
033    public static final String MISSING_JANINO_MSG = "Could not find Janino library on the class path. Skipping conditional processing.";
034    public static final String MISSING_JANINO_SEE = "See also " + CoreConstants.CODES_URL + "#ifJanino";
035
036    enum Branch {IF_BRANCH, ELSE_BRANCH; }
037    
038    IfModel ifModel = null;
039    
040    public IfModelHandler(Context context) {
041        super(context);
042    }
043
044    static public ModelHandlerBase makeInstance(Context context, ModelInterpretationContext ic) {
045        return new IfModelHandler(context);
046    }
047
048    @Override
049    protected Class<IfModel> getSupportedModelClass() {
050        return IfModel.class;
051    }
052    
053    @Override
054    public void handle(ModelInterpretationContext mic, Model model) throws ModelHandlerException {
055        
056        ifModel = (IfModel) model;
057        
058        if (!EnvUtil.isJaninoAvailable()) {
059            addError(MISSING_JANINO_MSG);
060            addError(MISSING_JANINO_SEE);
061            return;
062        }
063        
064        mic.pushModel(ifModel);
065        Condition condition = null;
066        int lineNum = model.getLineNumber();
067
068        String conditionStr = ifModel.getCondition();
069        if (!OptionHelper.isNullOrEmptyOrAllSpaces(conditionStr)) {
070            try {
071                conditionStr = OptionHelper.substVars(conditionStr, mic, context);
072            } catch (ScanException e) {
073               addError("Failed to parse input [" + conditionStr + "] on line "+lineNum, e);
074               ifModel.setBranchState(BranchState.IN_ERROR);
075               return;
076            }
077
078            try {
079                PropertyEvalScriptBuilder pesb = new PropertyEvalScriptBuilder(mic);
080                pesb.setContext(context);
081                condition = pesb.build(conditionStr);
082            } catch (Exception|NoClassDefFoundError e) {
083                ifModel.setBranchState(BranchState.IN_ERROR);
084                addError("Failed to parse condition [" + conditionStr + "] on line "+lineNum, e);
085                return;
086            }
087
088            if (condition != null) {
089                boolean boolResult = condition.evaluate();
090                addInfo("Condition ["+conditionStr+"] evaluated to "+boolResult+ " on line "+lineNum);
091                ifModel.setBranchState(boolResult);
092            } else {
093                addError("The condition variable is null. This should not occur.");
094                ifModel.setBranchState(BranchState.IN_ERROR);
095                return;
096            }
097        }
098    }
099    
100    
101    @Override
102    public void postHandle(ModelInterpretationContext mic, Model model) throws ModelHandlerException {
103
104        if(mic.isModelStackEmpty()) {
105            addError("Unexpected unexpected empty model stack.");
106            return;
107        }
108
109        Object o = mic.peekModel();
110        if (o != ifModel) {
111            addWarn("The object [" + o + "] on the top the of the stack is not the expected [" + ifModel);
112        } else {
113            mic.popModel();
114        }
115    }
116
117}