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 regular method invocation.
022 * Ex.
023 * <code>
024 * ${foo.bar()}
025 * </code>
026 *
027 * @since 1.0
028 * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
029 * @version $Id: JexlMethod.java 889760 2009-12-11 18:42:49Z sebb $
030 */
031 public interface JexlMethod {
032 /**
033 * Invocation method, called when the method invocation should be performed
034 * and a value returned.
035
036 * @param obj the object
037 * @param params method parameters.
038 * @return the result
039 * @throws Exception on any error.
040 */
041 Object invoke(Object obj, Object[] params) throws Exception;
042
043 /**
044 * Attempts to reuse this JexlMethod, checking that it is compatible with
045 * the actual set of arguments.
046 * Related to isCacheable since this method is often used with cached JexlMethod instances.
047 * @param obj the object to invoke the method upon
048 * @param name the method name
049 * @param params the method arguments
050 * @return the result of the method invocation that should be checked by tryFailed to determine if it succeeded
051 * or failed.
052 */
053 Object tryInvoke(String name, Object obj, Object[] params);
054
055 /**
056 * Checks whether a tryInvoke failed or not.
057 * @param rval the value returned by tryInvoke
058 * @return true if tryInvoke failed, false otherwise
059 */
060 boolean tryFailed(Object rval);
061
062 /**
063 * Specifies if this JexlMethod is cacheable and able to be reused for this
064 * class of object it was returned for.
065 *
066 * @return true if can be reused for this class, false if not
067 */
068 boolean isCacheable();
069
070 /**
071 * returns the return type of the method invoked.
072 * @return return type
073 */
074 Class<?> getReturnType();
075 }