001/*
002 * Logback: the reliable, generic, fast and flexible logging framework.
003 * Copyright (C) 1999-2026, 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 v2.0 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    public static final String NEW_OPERATOR_DISALLOWED_MSG = "The 'condition' attribute may not contain the 'new' operator.";
037    public static final String NEW_OPERATOR_DISALLOWED_SEE = "See also " + CoreConstants.CODES_URL + "#conditionNew";
038
039    public static final String CONDITION_ATTR_DEPRECATED_MSG = "The 'condition' attribute in <if> element is deprecated and slated for removal. Use <condition> element instead.";
040    public static final String CONDITION_ATTR_DEPRECATED_SEE = "See also " + CoreConstants.CODES_URL + "#conditionAttributeDeprecation";
041
042    enum Branch {IF_BRANCH, ELSE_BRANCH; }
043    
044    IfModel ifModel = null;
045    
046    public IfModelHandler(Context context) {
047        super(context);
048    }
049
050    static public ModelHandlerBase makeInstance(Context context, ModelInterpretationContext ic) {
051        return new IfModelHandler(context);
052    }
053
054    @Override
055    protected Class<IfModel> getSupportedModelClass() {
056        return IfModel.class;
057    }
058    
059    @Override
060    public void handle(ModelInterpretationContext mic, Model model) throws ModelHandlerException {
061        
062        ifModel = (IfModel) model;
063        mic.pushModel(ifModel);
064        Object micTopObject = mic.peekObject();
065        String conditionStr = ifModel.getCondition();
066        emitDeprecationWarningIfNecessary(conditionStr);
067
068
069        if(micTopObject instanceof BranchState) {
070            BranchState branchState = (BranchState) micTopObject;
071            ifModel.setBranchState(branchState);
072            // consume the BranchState at top of the object stack
073            mic.popObject();
074        } else {
075            janinoFallback(mic, model, conditionStr);
076        }
077    }
078
079    private void janinoFallback(ModelInterpretationContext mic, Model model, String conditionStr) {
080        if (!EnvUtil.isJaninoAvailable()) {
081            addError(MISSING_JANINO_MSG);
082            addError(MISSING_JANINO_SEE);
083            return;
084        }
085
086        Condition condition = null;
087        int lineNum = model.getLineNumber();
088
089        if (!OptionHelper.isNullOrEmptyOrAllSpaces(conditionStr)) {
090            try {
091                conditionStr = OptionHelper.substVars(conditionStr, mic, context);
092            } catch (ScanException e) {
093               addError("Failed to parse input [" + conditionStr + "] on line "+lineNum, e);
094               ifModel.setBranchState(BranchState.IN_ERROR);
095                return;
096            }
097
098            // do not allow 'new' operator
099            if(hasNew(conditionStr)) {
100                addError(NEW_OPERATOR_DISALLOWED_MSG);
101                addError(NEW_OPERATOR_DISALLOWED_SEE);
102                return;
103            }
104
105            try {
106                PropertyEvalScriptBuilder pesb = new PropertyEvalScriptBuilder(mic);
107                pesb.setContext(context);
108                condition = pesb.build(conditionStr);
109            } catch (Exception|NoClassDefFoundError e) {
110                ifModel.setBranchState(BranchState.IN_ERROR);
111                addError("Failed to parse condition [" + conditionStr + "] on line "+lineNum, e);
112                return;
113            }
114
115            if (condition != null) {
116                boolean boolResult = condition.evaluate();
117                addInfo("Condition ["+conditionStr+"] evaluated to "+boolResult+ " on line "+lineNum);
118                ifModel.setBranchState(boolResult);
119            } else {
120                addError("The condition variable is null. This should not occur.");
121                ifModel.setBranchState(BranchState.IN_ERROR);
122                return;
123            }
124        }
125    }
126
127    private void emitDeprecationWarningIfNecessary(String conditionStr) {
128        if(!OptionHelper.isNullOrEmptyOrAllSpaces(conditionStr)) {
129            addWarn(CONDITION_ATTR_DEPRECATED_MSG);
130            addWarn(CONDITION_ATTR_DEPRECATED_SEE);
131        }
132    }
133
134
135    private boolean hasNew(String conditionStr) {
136        return conditionStr.contains("new ");
137    }
138
139    @Override
140    public void postHandle(ModelInterpretationContext mic, Model model) throws ModelHandlerException {
141
142        if(mic.isModelStackEmpty()) {
143            addError("Unexpected unexpected empty model stack.");
144            return;
145        }
146
147        Object o = mic.peekModel();
148        if (o != ifModel) {
149            addWarn("The object [" + o + "] on the top the of the stack is not the expected [" + ifModel);
150        } else {
151            mic.popModel();
152        }
153    }
154
155}