/*
* 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 javax.servlet.jsp;

import javax.el.ELContextListener;
import javax.el.ELResolver;
import javax.el.ExpressionFactory;

/**
 * <p>
 * Stores <i>application</i>-scoped information for the JSP container.
 * </p>
 * @since 2.1
 */
public interface JspApplicationContext {

	/**
	 * <p>
	 * Registers an <code>ELContextListener</code> that will notified whenever
	 * a new <code>ELContext</code> is created.
	 * </p>
	 * <p>
	 * At the very least, any <code>ELContext</code> instantiated will have reference
	 * to the <code>JspContext</code> under <code>JspContext.class</code>.
	 * </p>
	 * 
	 * @param listener
	 */
	public void addELContextListener(ELContextListener listener);
	
	/**
	 * <p>
	 * Adds an <code>ELResolver</code> to the chain of EL variable and property management
	 * within JSP pages and Tag files.
	 * </p>
	 * <p>
	 * JSP has a default set of ELResolvers to chain for all EL evaluation:
	 * <ul>
	 * <li><code>ImplicitObjectELResolver</code></li>
	 * <li><code>ELResolver</code> instances registered with this method</li>
	 * <li><code>MapELResolver</code></li>
	 * <li><code>ListELResolver</code></li>
	 * <li><code>ArrayELResolver</code></li>
	 * <li><code>BeanELResolver</code></li>
	 * <li><code>ScopedAttributeELResolver</code></li>
	 * </ul>
	 * </p>
	 * 
	 * @param resolver an additional resolver
	 * @throws IllegalStateException if called after the application's <code>ServletContextListeners</code> have been initialized.
	 */
	public void addELResolver(ELResolver resolver) throws IllegalStateException;
	
	/**
	 * <p>
	 * Returns the JSP container's <code>ExpressionFactory</code> implementation for EL use.
	 * </p>
	 * 
	 * @return an <code>ExpressionFactory</code> implementation
	 */
	public ExpressionFactory getExpressionFactory();
	
}