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}