001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    
018    package org.apache.commons.jexl2.introspection;
019    
020    /**
021     * Interface used for setting values that appear to be properties.
022     * Ex.
023     * <code>
024     * ${foo.bar = "hello"}
025     * </code>
026     * @since 1.0
027     * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
028     * @version $Id: JexlPropertySet.java 889760 2009-12-11 18:42:49Z sebb $
029     */
030    public interface JexlPropertySet {
031        /**
032         * Method used to set the property value of an object.
033         * 
034         * @param obj Object on which the property setter will be called with the value
035         * @param arg value to be set
036         * @return the value returned from the set operation (impl specific)
037         * @throws Exception on any error.
038         */
039        Object invoke(Object obj, Object arg) throws Exception;
040    
041        /**
042         * Attempts to reuse this JexlPropertySet, checking that it is compatible with
043         * the actual set of arguments.
044         * @param obj the object to invoke the the get upon
045         * @param key the property key to get
046         * @param value the property value to set
047         * @return the result of the method invocation that should be checked by tryFailed to determine if it succeeded
048         * or failed.
049         */
050        Object tryInvoke(Object obj, Object key, Object value);
051    
052        /**
053         * Checks whether a tryInvoke failed or not.
054         * @param rval the value returned by tryInvoke
055         * @return true if tryInvoke failed, false otherwise
056         */
057        boolean tryFailed(Object rval);
058        
059        /**
060         * Specifies if this JexlPropertySet is cacheable and able to be reused for
061         * this class of object it was returned for.
062         * 
063         * @return true if can be reused for this class, false if not
064         */
065        boolean isCacheable();
066    }