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;
019    
020    import java.io.BufferedReader;
021    import java.io.File;
022    import java.io.InputStreamReader;
023    
024    /**
025     * Test application for JEXL.
026     *
027     * @since 2.0
028     */
029    public class Main {
030        /**
031         * Test application for JEXL
032         * 
033         * If a single argument is present, it is treated as a filename of a JEXL
034         * script to be executed as a script. Any exceptions terminate the application.
035         * 
036         * Otherwise, lines are read from standard input and evaluated.
037         * ParseExceptions and JexlExceptions are logged, and do not cause the application to exit.
038         * This is done so that interactive testing is easier.
039         * 
040         * @param args (optional) filename to execute. Stored in the args variable.
041         * 
042         * @throws Exception if parsing or IO fail
043         */
044        public static void main(String[] args) throws Exception {
045            JexlEngine engine = new JexlEngine();
046            JexlContext context = new MapContext();
047            context.set("args", args);
048            if (args.length == 1) {
049                Script script = engine.createScript(new File(args[0]));
050                Object value = script.execute(context);
051                System.out.println("Return value: " + value);
052            } else {
053                BufferedReader console = new BufferedReader(new InputStreamReader(System.in));
054                String line;
055                System.out.print("> ");
056                while (null != (line = console.readLine())) {
057                    try {
058                        Expression expression = engine.createExpression(line);
059                        Object value = expression.evaluate(context);
060                        System.out.println("Return value: " + value);
061                    } catch (JexlException e) {
062                        System.out.println(e.getLocalizedMessage());
063                    }
064                    System.out.print("> ");
065                }
066            }
067        }
068    }