| // Copyright 2016 The Bazel Authors. 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.starlark; |
| |
| import com.google.devtools.build.lib.events.Event; |
| import com.google.devtools.build.lib.events.EventHandler; |
| import com.google.devtools.build.lib.events.EventKind; |
| import com.google.devtools.build.lib.syntax.EvalException; |
| import com.google.devtools.build.lib.syntax.EvalUtils; |
| import com.google.devtools.build.lib.syntax.Module; |
| import com.google.devtools.build.lib.syntax.Mutability; |
| import com.google.devtools.build.lib.syntax.ParserInput; |
| import com.google.devtools.build.lib.syntax.Printer; |
| import com.google.devtools.build.lib.syntax.StarlarkThread; |
| import com.google.devtools.build.lib.syntax.SyntaxError; |
| import java.io.BufferedReader; |
| import java.io.IOException; |
| import java.io.InputStreamReader; |
| import java.nio.charset.Charset; |
| import java.nio.charset.StandardCharsets; |
| import java.nio.file.Files; |
| import java.nio.file.Paths; |
| |
| /** |
| * Starlark is a standalone starlark intepreter. The environment doesn't |
| * contain Bazel-specific functions and variables. Load statements are |
| * forbidden for the moment. |
| */ |
| class Starlark { |
| private static final String START_PROMPT = ">> "; |
| private static final String CONTINUATION_PROMPT = ".. "; |
| |
| private static final EventHandler PRINT_HANDLER = |
| new EventHandler() { |
| @Override |
| public void handle(Event event) { |
| if (event.getKind() == EventKind.ERROR) { |
| System.err.println(event.getMessage()); |
| } else { |
| System.out.println(event.getMessage()); |
| } |
| } |
| }; |
| |
| private static final Charset CHARSET = StandardCharsets.ISO_8859_1; |
| private final BufferedReader reader = |
| new BufferedReader(new InputStreamReader(System.in, CHARSET)); |
| private final Mutability mutability = Mutability.create("interpreter"); |
| private final StarlarkThread thread = |
| StarlarkThread.builder(mutability) |
| .useDefaultSemantics() |
| .setGlobals( |
| Module.createForBuiltins(com.google.devtools.build.lib.syntax.Starlark.UNIVERSE)) |
| .setEventHandler(PRINT_HANDLER) |
| .build(); |
| |
| private String prompt() { |
| StringBuilder input = new StringBuilder(); |
| System.out.print(START_PROMPT); |
| try { |
| String lineSeparator = ""; |
| while (true) { |
| String line = reader.readLine(); |
| if (line == null) { |
| return null; |
| } |
| if (line.isEmpty()) { |
| return input.toString(); |
| } |
| input.append(lineSeparator).append(line); |
| lineSeparator = "\n"; |
| System.out.print(CONTINUATION_PROMPT); |
| } |
| } catch (IOException io) { |
| io.printStackTrace(); |
| return null; |
| } |
| } |
| |
| /** Provide a REPL evaluating Starlark code. */ |
| @SuppressWarnings("CatchAndPrintStackTrace") |
| public void readEvalPrintLoop() { |
| String line; |
| |
| // TODO(adonovan): parse a compound statement, like the Python and |
| // go.starlark.net REPLs. This requires a new grammar production, and |
| // integration with the lexer so that it consumes new |
| // lines only until the parse is complete. |
| |
| while ((line = prompt()) != null) { |
| ParserInput input = ParserInput.fromLines(line); |
| try { |
| Object result = EvalUtils.execAndEvalOptionalFinalExpression(input, thread); |
| if (result != null) { |
| System.out.println(Printer.repr(result)); |
| } |
| } catch (SyntaxError ex) { |
| for (Event ev : ex.errors()) { |
| System.err.println(ev); |
| } |
| } catch (EvalException ex) { |
| // TODO(adonovan): show Starlark (not Java) stack. |
| ex.printStackTrace(); |
| } catch (InterruptedException ex) { |
| System.err.println("Interrupted"); |
| } |
| } |
| } |
| |
| /** Execute a Starlark file. */ |
| public int executeFile(String path) { |
| String content; |
| try { |
| content = new String(Files.readAllBytes(Paths.get(path)), CHARSET); |
| return execute(content); |
| } catch (Exception e) { |
| e.printStackTrace(); |
| return 1; |
| } |
| } |
| |
| /** Execute a Starlark file. */ |
| public int execute(String content) { |
| ParserInput input = ParserInput.create(content, null); |
| try { |
| EvalUtils.exec(input, thread); |
| return 0; |
| } catch (SyntaxError ex) { |
| for (Event ev : ex.errors()) { |
| System.err.println(ev); |
| } |
| return 1; |
| } catch (EvalException e) { |
| System.err.println(e.print()); |
| return 1; |
| } catch (Exception e) { |
| e.printStackTrace(System.err); |
| return 1; |
| } |
| } |
| |
| public static void main(String[] args) { |
| int ret = 0; |
| if (args.length == 0) { |
| new Starlark().readEvalPrintLoop(); |
| } else if (args.length == 1 && !args[0].equals("-c")) { |
| ret = new Starlark().executeFile(args[0]); |
| } else if (args.length == 2 && args[0].equals("-c")) { |
| ret = new Starlark().execute(args[1]); |
| } else { |
| System.err.println("USAGE: Starlark [-c \"<cmdLineProgram>\" | <fileName>]"); |
| ret = 1; |
| } |
| System.exit(ret); |
| } |
| } |