    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
    018package org.apache.commons.jexl3.scripting;
    019
    020import java.io.BufferedReader;
    021import java.io.File;
    022import java.io.FileInputStream;
    023import java.io.InputStreamReader;
    024import java.io.PrintStream;
    025import java.nio.charset.Charset;
    026
    027import javax.script.ScriptEngine;
    028import javax.script.ScriptException;
    029
    030/**
    031 * Test application for JexlScriptEngine (JSR-223 implementation).
    032 *
    033 * @since 2.0
    034 */
    035public class Main {
    036
    037    /**
    038     * Test application for JexlScriptEngine (JSR-223 implementation).
    039     *
    040     * If a single argument is present, it is treated as a file name of a JEXL
    041     * script to be evaluated. Any exceptions terminate the application.
    042     *
    043     * Otherwise, lines are read from standard input and evaluated.
    044     * ScriptExceptions are logged, and do not cause the application to exit.
    045     * This is done so that interactive testing is easier.
    046     *
    047     * @param args (optional) file name to evaluate. Stored in the args variable.
    048     *
    049     * @throws Exception if parsing or IO fail
    050     */
    051    public static void main(final String[] args) throws Exception {
    052        final JexlScriptEngineFactory fac = new JexlScriptEngineFactory();
    053        final ScriptEngine engine = fac.getScriptEngine();
    054        final PrintStream out = System.out;
    055        engine.put("args", args);
    056        if (args.length == 1){
    057            final Object value = engine.eval(read(null, args[0]));
    058            out.println("Return value: "+value);
    059        } else {
    060            final BufferedReader console = read(null, null);
    061            String line;
    062            System.out.print("> ");
    063            while(null != (line=console.readLine())){
    064                try {
    065                    final Object value = engine.eval(line);
    066                    out.println("Return value: "+value);
    067                } catch (final ScriptException e) {
    068                    out.println(e.getLocalizedMessage());
    069                }
    070                out.print("> ");
    071            }
    072        }
    073    }
    074
    075    /**
    076     * Reads an input.
    077     *
    078     * @param charset the charset or null for default charset
    079     * @param fileName the file name or null for stdin
    080     * @return the reader
    081     * @throws Exception if anything goes wrong
    082     */
    083    static BufferedReader read(final Charset charset, final String fileName) throws Exception {
    084        return new BufferedReader(
    085            new InputStreamReader(
    086                    fileName == null
    087                        ? System.in
    088                        : new FileInputStream(new File(fileName)),
    089                    charset == null
    090                        ? Charset.defaultCharset()
    091                        : charset));
    092    }
    093}