content: /*
   * Copyright 2010-2025 Hyland Software, Inc. and its affiliates.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.activiti.engine.impl.bpmn.helper;
  
  import org.activiti.engine.ActivitiIllegalArgumentException;
  import org.activiti.engine.delegate.Expression;
  import org.activiti.engine.delegate.event.ActivitiEntityEvent;
  import org.activiti.engine.delegate.event.ActivitiEvent;
  import org.activiti.engine.delegate.event.ActivitiEventListener;
  import org.activiti.engine.impl.el.NoExecutionVariableScope;
  
  /**
   * An {@link ActivitiEventListener} implementation which resolves an expression to a delegate {@link ActivitiEventListener} instance and uses this for event notification. <br>
   * <br>
   * In case an entityClass was passed in the constructor, only events that are {@link ActivitiEntityEvent}'s that target an entity of the given type, are dispatched to the delegate.
   *
  
   */
  public class DelegateExpressionActivitiEventListener extends BaseDelegateEventListener {
  
      protected Expression expression;
      protected boolean failOnException = false;
  
      public DelegateExpressionActivitiEventListener(Expression expression, Class<?> entityClass) {
          this.expression = expression;
          setEntityClass(entityClass);
      }
  
      @Override
      public void onEvent(ActivitiEvent event) {
          if (isValidEvent(event)) {
              Object delegate = DelegateExpressionUtil.resolveDelegateExpression(
                  expression,
                  new NoExecutionVariableScope()
              );
              if (delegate instanceof ActivitiEventListener) {
                  // Cache result of isFailOnException() from delegate-instance
                  // until next event is received. This prevents us from having to resolve
                  // the expression twice when an error occurs.
                  failOnException = ((ActivitiEventListener) delegate).isFailOnException();
  
                  // Call the delegate
                  ((ActivitiEventListener) delegate).onEvent(event);
              } else {
                  // Force failing, since the exception we're about to throw
                  // cannot be ignored, because it did not originate from the listener itself
                  failOnException = true;
                  throw new ActivitiIllegalArgumentException(
                      "Delegate expression " +
                      expression +
                      " did not resolve to an implementation of " +
                      ActivitiEventListener.class.getName()
                  );
              }
          }
      }
  
      @Override
      public boolean isFailOnException() {
          return failOnException;
      }
  }
  