DefineModelHandler.java

/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2022, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.core.model.processor;

import ch.qos.logback.core.Context;
import ch.qos.logback.core.joran.action.ActionUtil;
import ch.qos.logback.core.joran.action.ActionUtil.Scope;
import ch.qos.logback.core.model.DefineModel;
import ch.qos.logback.core.model.Model;
import ch.qos.logback.core.spi.LifeCycle;
import ch.qos.logback.core.spi.PropertyDefiner;
import ch.qos.logback.core.util.OptionHelper;

/**
 * Instantiate class for define property value. Get future property name and
 * property definer class from attributes. Some property definer properties
 * could be used. After defining put new property to context.
 * 
 * @author Aleksey Didik
 */
public class DefineModelHandler extends ModelHandlerBase {

    boolean inError;
    PropertyDefiner definer;
    String propertyName;
    Scope scope;

    public DefineModelHandler(Context context) {
        super(context);
    }

    static public DefineModelHandler makeInstance(Context context, ModelInterpretationContext ic) {
        return new DefineModelHandler(context);
    }

    @Override
    protected Class<DefineModel> getSupportedModelClass() {
        return DefineModel.class;
    }

    @Override
    public void handle(ModelInterpretationContext interpretationContext, Model model) throws ModelHandlerException {
        definer = null;
        inError = false;
        propertyName = null;

        DefineModel defineModel = (DefineModel) model;

        propertyName = defineModel.getName();
        String scopeStr = defineModel.getScopeStr();

        scope = ActionUtil.stringToScope(scopeStr);

        if (OptionHelper.isNullOrEmptyOrAllSpaces(propertyName)) {
            addError("Missing property name for property definer. Near [" + model.getTag() + "] line "
                    + model.getLineNumber());
            inError = true;
        }

        // read property definer class name
        String className = defineModel.getClassName();
        if (OptionHelper.isNullOrEmptyOrAllSpaces(className)) {
            addError("Missing class name for property definer. Near [" + model.getTag() + "] line "
                    + model.getLineNumber());
            inError = true;
        } else {
            className = interpretationContext.getImport(className);
        }

        if (inError)
            return;

        // try to instantiate property definer
        try {
            addInfo("About to instantiate property definer of type [" + className + "]");
            definer = (PropertyDefiner) OptionHelper.instantiateByClassName(className, PropertyDefiner.class, context);
            definer.setContext(context);
            interpretationContext.pushObject(definer);
        } catch (Exception oops) {
            inError = true;
            addError("Could not create an PropertyDefiner of type [" + className + "].", oops);
            throw new ModelHandlerException(oops);
        }

    }

    /**
     * Now property definer is initialized by all properties and we can put property
     * value to context
     */
    @Override
    public void postHandle(ModelInterpretationContext interpretationContext, Model model) throws ModelHandlerException {
        if (inError) {
            return;
        }

        Object o = interpretationContext.peekObject();

        if (o != definer) {
            addWarn("The object at the of the stack is not the property definer for property named [" + propertyName
                    + "] pushed earlier.");
        } else {
            interpretationContext.popObject();
            if (definer instanceof LifeCycle)
                ((LifeCycle) definer).start();

            // let's put defined property and value to context but only if it is
            // not null
            String propertyValue = definer.getPropertyValue();
            if (propertyValue != null) {
                addInfo("Setting property " + propertyName + "=" + propertyValue + " in scope " + scope);
                ActionUtil.setProperty(interpretationContext, propertyName, propertyValue, scope);
            }
        }

    }
}