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     */
029    public interface JexlMethod {
030        /**
031         * Invocation method, called when the method invocation should be performed
032         * and a value returned.
033    
034         * @param obj the object
035         * @param params method parameters.
036         * @return the result
037         * @throws Exception on any error.
038         */
039        Object invoke(Object obj, Object[] params) throws Exception;
040    
041        /**
042         * Attempts to reuse this JexlMethod, checking that it is compatible with
043         * the actual set of arguments.
044         * Related to isCacheable since this method is often used with cached JexlMethod instances.
045         * @param obj the object to invoke the method upon
046         * @param name the method name
047         * @param params the method arguments
048         * @return the result of the method invocation that should be checked by tryFailed to determine if it succeeded
049         * or failed.
050         */
051        Object tryInvoke(String name, Object obj, Object[] params);
052    
053        /**
054         * Checks whether a tryInvoke failed or not.
055         * @param rval the value returned by tryInvoke
056         * @return true if tryInvoke failed, false otherwise
057         */
058        boolean tryFailed(Object rval);
059    
060        /**
061         * Specifies if this JexlMethod is cacheable and able to be reused for this
062         * class of object it was returned for.
063         * 
064         * @return true if can be reused for this class, false if not
065         */
066        boolean isCacheable();
067    
068        /**
069         * returns the return type of the method invoked.
070         * @return return type
071         */
072        Class<?> getReturnType();
073    }