/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 com.opensymphony.xwork2;

import com.opensymphony.xwork2.util.ValueStack;

/**
 * Provides hooks for handling key action events
 */
public interface ActionEventListener {
    /**
     * Called after an action has been created. 
     * 
     * @param action The action
     * @param stack The current value stack
     * @return The action to use
     */
    public Object prepare(Object action, ValueStack stack);
    
    /**
     * Called when an exception is thrown by the action
     * 
     * @param t The exception/error that was thrown
     * @param stack The current value stack
     * @return A result code to execute, can be null
     */
    public String handleException(Throwable t, ValueStack stack);
}