src/main/java/net/starlark/java/cmd/Main.java - bazel - Git at Google

 // 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 net.starlark.java.cmd;

 import static java.nio.charset.StandardCharsets.UTF_8;

 import java.io.BufferedReader;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.time.Duration;
 import java.util.List;
 import net.starlark.java.eval.EvalException;
 import net.starlark.java.eval.Module;
 import net.starlark.java.eval.Mutability;
 import net.starlark.java.eval.Starlark;
 import net.starlark.java.eval.StarlarkSemantics;
 import net.starlark.java.eval.StarlarkThread;
 import net.starlark.java.syntax.FileOptions;
 import net.starlark.java.syntax.ParserInput;
 import net.starlark.java.syntax.StarlarkFile;
 import net.starlark.java.syntax.Statement;
 import net.starlark.java.syntax.SyntaxError;

 /**
  * Main is a standalone interpreter for the core Starlark language. It does not yet support load
  * statements.
  *
  * <p>The sad class name is due to the linting tool, which forbids lowercase "starlark", and Java's
  * lack of renaming imports, which makes the name "Starlark" impractical due to conflicts with
  * eval.Starlark.
  */
 class Main {
   private static final String START_PROMPT = ">> ";
   private static final String CONTINUATION_PROMPT = ".. ";

   private static final BufferedReader reader =
       new BufferedReader(new InputStreamReader(System.in, UTF_8));
   private static final StarlarkThread thread;
   private static final Module module = Module.create();

   // Variables bound by load in one REPL chunk are visible in the next.
   private static final FileOptions OPTIONS =
       FileOptions.DEFAULT.toBuilder().allowToplevelRebinding(true).loadBindsGlobally(true).build();

   static {
     Mutability mu = Mutability.create("interpreter");
     thread = new StarlarkThread(mu, StarlarkSemantics.DEFAULT);
     thread.setPrintHandler((th, msg) -> System.out.println(msg));
   }

   // Prompts the user for a chunk of input, and returns it.
   private static String prompt() {
     StringBuilder input = new StringBuilder();
     System.out.print(START_PROMPT);
     try {
       String lineSeparator = "";
       loop:
       while (true) {
         String line = reader.readLine();
         if (line == null) {
           return null;
         }
         if (line.isEmpty()) {
           break loop; // a blank line ends the chunk
         }
         input.append(lineSeparator).append(line);

         // Read lines until input produces valid statements, unless the last is if/def/for,
         // which can be multiline, in which case we must wait for a blank 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.
         StarlarkFile file = StarlarkFile.parse(ParserInput.fromString(input.toString(), "<stdin>"));
         if (file.ok()) {
           List<Statement> stmts = file.getStatements();
           if (!stmts.isEmpty()) {
             Statement last = stmts.get(stmts.size() - 1);
             switch (last.kind()) {
               case IF:
               case DEF:
               case FOR:
                 break; // keep going until blank line
               default:
                 break loop;
             }
           }
         }

         lineSeparator = "\n";
         System.out.print(CONTINUATION_PROMPT);
       }
     } catch (IOException e) {
       System.err.format("Error reading line: %s\n", e);
       return null;
     }
     return input.toString();
   }

   /** Provide a REPL evaluating Starlark code. */
   @SuppressWarnings("CatchAndPrintStackTrace")
   private static void readEvalPrintLoop() {
     System.err.println("Welcome to Starlark (java.starlark.net)");
     String line;

     while ((line = prompt()) != null) {
       ParserInput input = ParserInput.fromString(line, "<stdin>");
       try {
         Object result = Starlark.execFile(input, OPTIONS, module, thread);
         if (result != Starlark.NONE) {
           System.out.println(Starlark.repr(result));
         }
       } catch (SyntaxError.Exception ex) {
         for (SyntaxError error : ex.errors()) {
           System.err.println(error);
         }
       } catch (EvalException ex) {
         // TODO(adonovan): provide a SourceReader. Requires that we buffer the
         // entire history so that line numbers don't reset in each chunk.
         System.err.println(ex.getMessageWithStack());
       } catch (InterruptedException ex) {
         System.err.println("Interrupted");
       }
     }
   }

   /** Execute a Starlark file. */
   private static int execute(ParserInput input) {
     try {
       Starlark.execFile(input, OPTIONS, module, thread);
       return 0;
     } catch (SyntaxError.Exception ex) {
       for (SyntaxError error : ex.errors()) {
         System.err.println(error);
       }
       return 1;
     } catch (EvalException ex) {
       System.err.println(ex.getMessageWithStack());
       return 1;
     } catch (InterruptedException e) {
       System.err.println("Interrupted");
       return 1;
     }
   }

   public static void main(String[] args) throws IOException {
     String file = null;
     String cmd = null;
     String cpuprofile = null;

     // parse flags
     int i;
     for (i = 0; i < args.length; i++) {
       if (!args[i].startsWith("-")) {
         break;
       }
       if (args[i].equals("--")) {
         i++;
         break;
       }
       if (args[i].equals("-c")) {
         if (i + 1 == args.length) {
           throw new IOException("-c <cmd> flag needs an argument");
         }
         cmd = args[++i];
       } else if (args[i].equals("-cpuprofile")) {
         if (i + 1 == args.length) {
           throw new IOException("-cpuprofile <file> flag needs an argument");
         }
         cpuprofile = args[++i];
       } else {
         throw new IOException("unknown flag: " + args[i]);
       }
     }
     // positional arguments
     if (i < args.length) {
       if (i + 1 < args.length) {
         throw new IOException("too many positional arguments");
       }
       file = args[i];
     }

     if (cpuprofile != null) {
       FileOutputStream out = new FileOutputStream(cpuprofile);
       Starlark.startCpuProfile(out, Duration.ofMillis(10));
     }

     int exit;
     if (file == null) {
       if (cmd != null) {
         exit = execute(ParserInput.fromString(cmd, "<command-line>"));
       } else {
         readEvalPrintLoop();
         exit = 0;
       }
     } else if (cmd == null) {
       try {
         exit = execute(ParserInput.readFile(file));
       } catch (IOException e) {
         // This results in such lame error messages as:
         // "Error reading a.star: java.nio.file.NoSuchFileException: a.star"
         System.err.format("Error reading %s: %s\n", file, e);
         exit = 1;
       }
     } else {
       System.err.println("usage: Starlark [-cpuprofile file] [-c cmd | file]");
       exit = 1;
     }

     if (cpuprofile != null) {
       Starlark.stopCpuProfile();
     }

     System.exit(exit);
   }
 }
	// 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 net.starlark.java.cmd;

	import static java.nio.charset.StandardCharsets.UTF_8;

	import java.io.BufferedReader;
	import java.io.FileOutputStream;
	import java.io.IOException;
	import java.io.InputStreamReader;
	import java.time.Duration;
	import java.util.List;
	import net.starlark.java.eval.EvalException;
	import net.starlark.java.eval.Module;
	import net.starlark.java.eval.Mutability;
	import net.starlark.java.eval.Starlark;
	import net.starlark.java.eval.StarlarkSemantics;
	import net.starlark.java.eval.StarlarkThread;
	import net.starlark.java.syntax.FileOptions;
	import net.starlark.java.syntax.ParserInput;
	import net.starlark.java.syntax.StarlarkFile;
	import net.starlark.java.syntax.Statement;
	import net.starlark.java.syntax.SyntaxError;

	/**
	* Main is a standalone interpreter for the core Starlark language. It does not yet support load
	* statements.
	*
	* <p>The sad class name is due to the linting tool, which forbids lowercase "starlark", and Java's
	* lack of renaming imports, which makes the name "Starlark" impractical due to conflicts with
	* eval.Starlark.
	*/
	class Main {
	private static final String START_PROMPT = ">> ";
	private static final String CONTINUATION_PROMPT = ".. ";

	private static final BufferedReader reader =
	new BufferedReader(new InputStreamReader(System.in, UTF_8));
	private static final StarlarkThread thread;
	private static final Module module = Module.create();

	// Variables bound by load in one REPL chunk are visible in the next.
	private static final FileOptions OPTIONS =
	FileOptions.DEFAULT.toBuilder().allowToplevelRebinding(true).loadBindsGlobally(true).build();

	static {
	Mutability mu = Mutability.create("interpreter");
	thread = new StarlarkThread(mu, StarlarkSemantics.DEFAULT);
	thread.setPrintHandler((th, msg) -> System.out.println(msg));
	}

	// Prompts the user for a chunk of input, and returns it.
	private static String prompt() {
	StringBuilder input = new StringBuilder();
	System.out.print(START_PROMPT);
	try {
	String lineSeparator = "";
	loop:
	while (true) {
	String line = reader.readLine();
	if (line == null) {
	return null;
	}
	if (line.isEmpty()) {
	break loop; // a blank line ends the chunk
	}
	input.append(lineSeparator).append(line);

	// Read lines until input produces valid statements, unless the last is if/def/for,
	// which can be multiline, in which case we must wait for a blank 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.
	StarlarkFile file = StarlarkFile.parse(ParserInput.fromString(input.toString(), "<stdin>"));
	if (file.ok()) {
	List<Statement> stmts = file.getStatements();
	if (!stmts.isEmpty()) {
	Statement last = stmts.get(stmts.size() - 1);
	switch (last.kind()) {
	case IF:
	case DEF:
	case FOR:
	break; // keep going until blank line
	default:
	break loop;
	}
	}
	}

	lineSeparator = "\n";
	System.out.print(CONTINUATION_PROMPT);
	}
	} catch (IOException e) {
	System.err.format("Error reading line: %s\n", e);
	return null;
	}
	return input.toString();
	}

	/** Provide a REPL evaluating Starlark code. */
	@SuppressWarnings("CatchAndPrintStackTrace")
	private static void readEvalPrintLoop() {
	System.err.println("Welcome to Starlark (java.starlark.net)");
	String line;

	while ((line = prompt()) != null) {
	ParserInput input = ParserInput.fromString(line, "<stdin>");
	try {
	Object result = Starlark.execFile(input, OPTIONS, module, thread);
	if (result != Starlark.NONE) {
	System.out.println(Starlark.repr(result));
	}
	} catch (SyntaxError.Exception ex) {
	for (SyntaxError error : ex.errors()) {
	System.err.println(error);
	}
	} catch (EvalException ex) {
	// TODO(adonovan): provide a SourceReader. Requires that we buffer the
	// entire history so that line numbers don't reset in each chunk.
	System.err.println(ex.getMessageWithStack());
	} catch (InterruptedException ex) {
	System.err.println("Interrupted");
	}
	}
	}

	/** Execute a Starlark file. */
	private static int execute(ParserInput input) {
	try {
	Starlark.execFile(input, OPTIONS, module, thread);
	return 0;
	} catch (SyntaxError.Exception ex) {
	for (SyntaxError error : ex.errors()) {
	System.err.println(error);
	}
	return 1;
	} catch (EvalException ex) {
	System.err.println(ex.getMessageWithStack());
	return 1;
	} catch (InterruptedException e) {
	System.err.println("Interrupted");
	return 1;
	}
	}

	public static void main(String[] args) throws IOException {
	String file = null;
	String cmd = null;
	String cpuprofile = null;

	// parse flags
	int i;
	for (i = 0; i < args.length; i++) {
	if (!args[i].startsWith("-")) {
	break;
	}
	if (args[i].equals("--")) {
	i++;
	break;
	}
	if (args[i].equals("-c")) {
	if (i + 1 == args.length) {
	throw new IOException("-c <cmd> flag needs an argument");
	}
	cmd = args[++i];
	} else if (args[i].equals("-cpuprofile")) {
	if (i + 1 == args.length) {
	throw new IOException("-cpuprofile <file> flag needs an argument");
	}
	cpuprofile = args[++i];
	} else {
	throw new IOException("unknown flag: " + args[i]);
	}
	}
	// positional arguments
	if (i < args.length) {
	if (i + 1 < args.length) {
	throw new IOException("too many positional arguments");
	}
	file = args[i];
	}

	if (cpuprofile != null) {
	FileOutputStream out = new FileOutputStream(cpuprofile);
	Starlark.startCpuProfile(out, Duration.ofMillis(10));
	}

	int exit;
	if (file == null) {
	if (cmd != null) {
	exit = execute(ParserInput.fromString(cmd, "<command-line>"));
	} else {
	readEvalPrintLoop();
	exit = 0;
	}
	} else if (cmd == null) {
	try {
	exit = execute(ParserInput.readFile(file));
	} catch (IOException e) {
	// This results in such lame error messages as:
	// "Error reading a.star: java.nio.file.NoSuchFileException: a.star"
	System.err.format("Error reading %s: %s\n", file, e);
	exit = 1;
	}
	} else {
	System.err.println("usage: Starlark [-cpuprofile file] [-c cmd \| file]");
	exit = 1;
	}

	if (cpuprofile != null) {
	Starlark.stopCpuProfile();
	}

	System.exit(exit);
	}
	}