001    package org.apache.commons.ognl;
002    
003    /*
004     * Licensed to the Apache Software Foundation (ASF) under one
005     * or more contributor license agreements.  See the NOTICE file
006     * distributed with this work for additional information
007     * regarding copyright ownership.  The ASF licenses this file
008     * to you under the Apache License, Version 2.0 (the
009     * "License"); you may not use this file except in compliance
010     * with the License.  You may obtain a copy of the License at
011     *
012     *   http://www.apache.org/licenses/LICENSE-2.0
013     *
014     * Unless required by applicable law or agreed to in writing,
015     * software distributed under the License is distributed on an
016     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017     * KIND, either express or implied.  See the License for the
018     * specific language governing permissions and limitations
019     * under the License.
020     */
021    
022    import java.util.Map;
023    
024    /**
025     * Interface for handling null results from Chains. Object has the opportunity to substitute an object for the null and
026     * continue.
027     * 
028     * @author Luke Blanshard (blanshlu@netscape.net)
029     * @author Drew Davidson (drew@ognl.org)
030     */
031    public interface NullHandler
032    {
033        /**
034         * Method called on target returned null.
035         */
036        Object nullMethodResult( Map<String, Object> context, Object target, String methodName, Object[] args );
037    
038        /**
039         * Property in target evaluated to null. Property can be a constant String property name or a DynamicSubscript.
040         */
041        Object nullPropertyValue( Map<String, Object> context, Object target, Object property );
042    }