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.IOException;
022import java.io.InputStreamReader;
023import java.io.OutputStreamWriter;
024import java.io.PrintWriter;
025import java.nio.charset.Charset;
026import java.nio.file.Files;
027import java.nio.file.Path;
028import java.nio.file.Paths;
029
030import javax.script.ScriptEngine;
031import javax.script.ScriptException;
032
033/**
034 * Test application for JexlScriptEngine (JSR-223 implementation).
035 *
036 * @since 2.0
037 */
038public class Main {
039
040    /** Default constructor */
041    public Main() { } // Keep Javadoc happy
042
043    /**
044     * Test application for JexlScriptEngine (JSR-223 implementation).
045     * <p>
046     * If a single argument is present, it is treated as a file name of a JEXL
047     * script to be evaluated. Any exceptions terminate the application.
048     * </p>
049     * Otherwise, lines are read from standard input and evaluated.
050     * ScriptExceptions are logged, and do not cause the application to exit.
051     * This is done so that interactive testing is easier.
052     * The line //q! ends the loop.
053     *
054     * @param args (optional) file name to evaluate. Stored in the args variable.
055     * @throws Exception if parsing or IO fail
056     */
057    public static void main(final String[] args) throws Exception {
058        try(BufferedReader in = args.length == 1? read(Paths.get(args[0])) : read(null);
059            PrintWriter out =  new PrintWriter(
060                new OutputStreamWriter(System.out, Charset.defaultCharset()),true)) {
061            run(in, out, args);
062        }
063    }
064
065    static void run(final BufferedReader in, final PrintWriter out, final Object[] args) throws Exception {
066        final JexlScriptEngineFactory fac = new JexlScriptEngineFactory();
067        final ScriptEngine engine = fac.getScriptEngine();
068        if (args != null && args.length > 0) {
069            engine.put("args", args);
070            final Object value = engine.eval(in);
071            out.println(">>: " + value);
072        } else {
073            String line;
074            out.print("> ");
075            while (null != (line = in.readLine())) {
076                if ("//q!".equals(line)) {
077                    break;
078                }
079                try {
080                    final Object value = engine.eval(line);
081                    out.println(">> " + value);
082                } catch (final ScriptException e) {
083                    out.println("!!>" + e.getLocalizedMessage());
084                }
085                out.print("> ");
086            }
087        }
088    }
089
090    /**
091     * Reads an input.
092     *
093     * @param path the file path or null for stdin
094     * @return the reader
095     * @throws IOException if anything goes wrong
096     */
097    static BufferedReader read(final Path path) throws IOException {
098        return new BufferedReader(new InputStreamReader(path == null
099            ? System.in
100            : Files.newInputStream(path), Charset.defaultCharset()));
101    }
102}