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