    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    }