| // Copyright 2015 Google Inc. All rights reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| package com.google.devtools.build.lib.syntax; |
| |
| import com.google.devtools.build.lib.events.Event; |
| import com.google.devtools.build.lib.events.EventHandler; |
| |
| import java.io.BufferedReader; |
| import java.io.IOException; |
| import java.io.InputStreamReader; |
| import java.nio.charset.Charset; |
| |
| /** |
| * SkylarkShell is a standalone shell executing Skylark. This is intended for |
| * testing purposes and not for end-users. This is very limited (environment is |
| * almost empty), but it can be used to play with the language and reproduce |
| * bugs. Imports and includes are not supported. |
| */ |
| class SkylarkShell { |
| |
| private static final String START_PROMPT = ">> "; |
| private static final String CONTINUATION_PROMPT = ".. "; |
| |
| public static final EventHandler PRINT_HANDLER = new EventHandler() { |
| @Override |
| public void handle(Event event) { |
| System.out.println(event.getMessage()); |
| } |
| }; |
| |
| private final BufferedReader reader = new BufferedReader( |
| new InputStreamReader(System.in, Charset.defaultCharset())); |
| private final Mutability mutability = Mutability.create("shell"); |
| private final Environment env = Environment.builder(mutability) |
| .setSkylark().setGlobals(Environment.SKYLARK).setEventHandler(PRINT_HANDLER).build(); |
| |
| public String read() { |
| StringBuilder input = new StringBuilder(); |
| System.out.print(START_PROMPT); |
| try { |
| while (true) { |
| String line = reader.readLine(); |
| if (line == null) { |
| return null; |
| } |
| if (line.isEmpty()) { |
| return input.toString(); |
| } |
| input.append("\n").append(line); |
| System.out.print(CONTINUATION_PROMPT); |
| } |
| } catch (IOException io) { |
| io.printStackTrace(); |
| return null; |
| } |
| } |
| |
| public void readEvalPrintLoop() { |
| String input; |
| while ((input = read()) != null) { |
| try { |
| Object result = env.eval(input); |
| if (result != null) { |
| System.out.println(Printer.repr(result)); |
| } |
| } catch (Exception e) { |
| e.printStackTrace(); |
| } |
| } |
| } |
| |
| public static void main(String[] args) { |
| new SkylarkShell().readEvalPrintLoop(); |
| } |
| } |