    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    }