NestedComplexPropertyIA.java

/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2013, 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.joran.action;

import java.util.Stack;

import ch.qos.logback.core.joran.spi.ElementPath;
import org.xml.sax.Attributes;

import ch.qos.logback.core.joran.spi.InterpretationContext;
import ch.qos.logback.core.joran.spi.NoAutoStartUtil;
import ch.qos.logback.core.joran.util.PropertySetter;
import ch.qos.logback.core.spi.ContextAware;
import ch.qos.logback.core.spi.LifeCycle;
import ch.qos.logback.core.util.AggregationType;
import ch.qos.logback.core.util.Loader;
import ch.qos.logback.core.util.OptionHelper;

/**
 * This action is responsible for tying together a parent object with a child
 * element for which there is no explicit rule.
 * 
 * @author Ceki Gülcü
 */
public class NestedComplexPropertyIA extends ImplicitAction {

  // actionDataStack contains ActionData instances
  // We use a stack of ActionData objects in order to support nested
  // elements which are handled by the same NestedComplexPropertyIA instance.
  // We push a ActionData instance in the isApplicable method (if the
  // action is applicable) and pop it in the end() method.
  // The XML well-formedness property will guarantee that a push will eventually
  // be followed by a corresponding pop.
  Stack<IADataForComplexProperty> actionDataStack = new Stack<IADataForComplexProperty>();

  public boolean isApplicable(ElementPath elementPath, Attributes attributes,
      InterpretationContext ic) {

    String nestedElementTagName = elementPath.peekLast();

    // calling ic.peekObject with an empty stack will throw an exception
    if (ic.isEmpty()) {
      return false;
    }

    Object o = ic.peekObject();
    PropertySetter parentBean = new PropertySetter(o);
    parentBean.setContext(context);

    AggregationType aggregationType = parentBean
        .computeAggregationType(nestedElementTagName);

    switch (aggregationType) {
    case NOT_FOUND:
    case AS_BASIC_PROPERTY:
    case AS_BASIC_PROPERTY_COLLECTION:
      return false;

      // we only push action data if NestComponentIA is applicable
    case AS_COMPLEX_PROPERTY_COLLECTION:
    case AS_COMPLEX_PROPERTY:
      IADataForComplexProperty ad = new IADataForComplexProperty(parentBean,
          aggregationType, nestedElementTagName);
      actionDataStack.push(ad);

      return true;
    default:
      addError("PropertySetter.computeAggregationType returned "
          + aggregationType);
      return false;
    }
  }

  public void begin(InterpretationContext ec, String localName,
      Attributes attributes) {
    // LogLog.debug("in NestComponentIA begin method");
    // get the action data object pushed in isApplicable() method call
    IADataForComplexProperty actionData = (IADataForComplexProperty) actionDataStack
        .peek();

    String className = attributes.getValue(CLASS_ATTRIBUTE);
    // perform variable name substitution
    className = ec.subst(className);

    Class<?> componentClass = null;
    try {

      if (!OptionHelper.isEmpty(className)) {
        componentClass = Loader.loadClass(className, context);
      } else {
        // guess class name via implicit rules
        PropertySetter parentBean = actionData.parentBean;
        componentClass = parentBean.getClassNameViaImplicitRules(actionData
            .getComplexPropertyName(), actionData.getAggregationType(), ec
            .getDefaultNestedComponentRegistry());
      }

      if (componentClass == null) {
        actionData.inError = true;
        String errMsg = "Could not find an appropriate class for property ["
            + localName + "]";
        addError(errMsg);
        return;
      }

      if (OptionHelper.isEmpty(className)) {
        addInfo("Assuming default type [" + componentClass.getName()
            + "] for [" + localName + "] property");
      }

      actionData.setNestedComplexProperty(componentClass.newInstance());

      // pass along the repository
      if (actionData.getNestedComplexProperty() instanceof ContextAware) {
        ((ContextAware) actionData.getNestedComplexProperty())
            .setContext(this.context);
      }
      //addInfo("Pushing component [" + localName
      //    + "] on top of the object stack.");
      ec.pushObject(actionData.getNestedComplexProperty());

    } catch (Exception oops) {
      actionData.inError = true;
      String msg = "Could not create component [" + localName + "] of type ["
          + className + "]";
      addError(msg, oops);
    }

  }

  public void end(InterpretationContext ec, String tagName) {

    // pop the action data object pushed in isApplicable() method call
    // we assume that each this begin
    IADataForComplexProperty actionData = (IADataForComplexProperty) actionDataStack
        .pop();

    if (actionData.inError) {
      return;
    }

    PropertySetter nestedBean = new PropertySetter(actionData
        .getNestedComplexProperty());
    nestedBean.setContext(context);

    // have the nested element point to its parent if possible
    if (nestedBean.computeAggregationType("parent") == AggregationType.AS_COMPLEX_PROPERTY) {
      nestedBean.setComplexProperty("parent", actionData.parentBean.getObj());
    }

    // start the nested complex property if it implements LifeCycle and is not
    // marked with a @NoAutoStart annotation
    Object nestedComplexProperty = actionData.getNestedComplexProperty();
    if (nestedComplexProperty instanceof LifeCycle
        && NoAutoStartUtil.notMarkedWithNoAutoStart(nestedComplexProperty)) {
      ((LifeCycle) nestedComplexProperty).start();
    }

    Object o = ec.peekObject();

    if (o != actionData.getNestedComplexProperty()) {
      addError("The object on the top the of the stack is not the component pushed earlier.");
    } else {
      ec.popObject();
      // Now let us attach the component
      switch (actionData.aggregationType) {
      case AS_COMPLEX_PROPERTY:
        actionData.parentBean.setComplexProperty(tagName, actionData
            .getNestedComplexProperty());

        break;
      case AS_COMPLEX_PROPERTY_COLLECTION:
        actionData.parentBean.addComplexProperty(tagName, actionData
            .getNestedComplexProperty());

        break;
      }
    }
  }

}