Support subcommands in pub and pub help.

sdk/lib/_internal/pub/bin/pub.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:args/args.dart';
 import 'package:path/path.dart' as path;
+import 'package:stack_trace/stack_trace.dart';
 
 import '../lib/src/command.dart';
 import '../lib/src/exit_codes.dart' as exit_codes;
+import '../lib/src/http.dart';
 import '../lib/src/io.dart';
 import '../lib/src/log.dart' as log;
 import '../lib/src/sdk.dart' as sdk;
 import '../lib/src/utils.dart';
 
 void main(List<String> arguments) {
   ArgResults options;
 
   try {
     options = PubCommand.pubArgParser.parse(arguments,
         allowTrailingOptions: true);
   } on FormatException catch (e) {
     log.error(e.message);
     log.error('Run "pub help" to see available options.');
     flushThenExit(exit_codes.USAGE);
     return;
   }
 
   if (options['version']) {
     log.message('Pub ${sdk.version}');
     return;
   }
 
   if (options['help']) {
     PubCommand.printGlobalUsage();
     return;
   }
 
-  if (options.command == null) {
-    if (options.rest.isEmpty) {
-      // No command was chosen.
-      PubCommand.printGlobalUsage();
-    } else {
-      log.error('Could not find a command named "${options.rest[0]}".');
-      log.error('Run "pub help" to see available commands.');
-      flushThenExit(exit_codes.USAGE);
-    }
-    return;
-  }
-
   if (options['trace']) {
     log.recordTranscript();
   }
 
   switch (options['verbosity']) {
     case 'normal': log.showNormal(); break;
     case 'io':     log.showIO(); break;
     case 'solver': log.showSolver(); break;
     case 'all':    log.showAll(); break;
     default:
@@ skipping 11 matching lines @@
   var cacheDir;
   if (Platform.environment.containsKey('PUB_CACHE')) {
     cacheDir = Platform.environment['PUB_CACHE'];
   } else if (Platform.operatingSystem == 'windows') {
     var appData = Platform.environment['APPDATA'];
     cacheDir = path.join(appData, 'Pub', 'Cache');
   } else {
     cacheDir = '${Platform.environment['HOME']}/.pub-cache';
   }
 
-  validatePlatform().then((_) {
-    PubCommand.commands[options.command.name].run(cacheDir, options, arguments);
+  validatePlatform().then((_) => runPub(cacheDir, options, arguments));
+}
+
+/// Runs the appropriate pub command parsed to [options] from [arguments] using

[nweiz, 2014/02/04 01:24:29]

I'm not sure what "parsed to [options] from [arguments]" means.

[Bob Nystrom, 2014/02/06 00:06:31]

Reworded.

+/// the system cache in [cacheDir].
+///
+/// Handles and correctly reports any errors that occur while running.
+void runPub(String cacheDir, ArgResults options, List<String> arguments) {
+  handleError(error, Chain chain) {

[nweiz, 2014/02/04 01:24:29]

I don't like how this is a separate named function outside of the normal flow of
the code. I think we originally did that because it was called multiple times,
but it's only used once now so let's move it back into [catchError].

[Bob Nystrom, 2014/02/06 00:06:31]

Done.

+    // This is basically the top-level exception handler so that we don't
+    // spew a stack trace on our users.
+    var message;
+
+    log.error(getErrorMessage(error));
+    log.fine("Exception type: ${error.runtimeType}");
+
+    if (options['trace'] || !isUserFacingException(error)) {
+      log.error(chain.terse);
+    } else {
+      log.fine(chain.terse);
+    }
+
+    if (error is ApplicationException && error.innerError != null) {
+      var message = "Wrapped exception: ${error.innerError}";
+      if (error.innerTrace != null) message = "$message\n${error.innerTrace}";
+      log.fine(message);
+    }
+
+    if (options['trace']) {
+      log.dumpTranscript();
+    } else if (!isUserFacingException(error)) {
+      log.error("""
+This is an unexpected error. Please run
+
+    pub --trace ${arguments.map((arg) => "'$arg'").join(' ')}
+
+and include the results in a bug report on http://dartbug.com/new.
+""");
+    }
+
+    return flushThenExit(chooseExitCode(error));
+  }
+
+  var captureStackChains =
+      options['trace'] ||
+      options['verbose'] ||
+      options['verbosity'] == 'all';
+
+  captureErrors(() {
+    return invokeCommand(cacheDir, options);

[nweiz, 2014/02/04 01:24:29]

Nit: =>

[Bob Nystrom, 2014/02/06 00:06:31]

Done.

+  }, captureStackChains: captureStackChains).catchError(handleError)
+      .then((_) {
+    // Explicitly exit on success to ensure that any dangling dart:io handles
+    // don't cause the process to never terminate.
+    return flushThenExit(exit_codes.SUCCESS);
   });
 }
 
+/// Returns the appropriate exit code for [exception], falling back on 1 if no
+/// appropriate exit code could be found.
+int chooseExitCode(exception) {
+  if (exception is HttpException || exception is HttpException ||
+      exception is SocketException || exception is PubHttpException) {
+    return exit_codes.UNAVAILABLE;
+  } else if (exception is FormatException) {
+    return exit_codes.DATA;
+  } else if (exception is UsageException) {
+    return exit_codes.USAGE;
+  } else {
+    return 1;
+  }
+}
+
+/// Walks the command tree and runs the selected pub command.
+Future invokeCommand(String cacheDir, ArgResults mainOptions) {
+  var commands = PubCommand.mainCommands;
+  var command;
+  var commandString = "pub";
+  var options = mainOptions;
+
+  while (commands.isNotEmpty) {
+    if (options.command == null) {
+      if (options.rest.isEmpty) {
+        if (command == null) {
+          // No top-level command was chosen.
+          PubCommand.printGlobalUsage();
+          return null;

[nweiz, 2014/02/04 01:24:29]

I know it works in this case, but I don't like returning null from functions
that declare Future. It makes it harder to re-use or move the function somewhere
else, since [then] won't work.

[Bob Nystrom, 2014/02/06 00:06:31]

Done.

+        }
+
+        command.usageError('Missing subcommand for "$commandString".');
+      } else {
+        if (command == null) {
+          PubCommand.commandUsageError(commands,
+              'Could not find a command named "${options.rest[0]}".');
+        }
+
+        command.usageError(
+            'Could not find a subcommand named "${options.rest[0]}" '
+            'for "$commandString".');

[nweiz, 2014/02/04 01:24:29]

Nit: when writing multiline strings like this, I like to add an extra level of
indentation when the previous line didn't end in a newline. This helps visually
differentiate actual newlines in the text from newlines imposed by line-length
limitations.

[Bob Nystrom, 2014/02/06 00:06:31]

Moved the first line up. I think that makes it consistent with other multiline
literals. We have lots of code like:

blah("some string that has no line break "
    "the rest of the string");

Where the second line is only +4. Made this match.

+      }
+    }
+
+    // Step into the command.
+    options = options.command;
+    command = commands[options.name];
+    commands = command.subcommands;
+    commandString += " ${options.name}";
+
+    if (options['help']) {
+      command.printUsage();
+      return null;
+    }
+  }
+
+  // Make sure there aren't unexpected arguments.
+  if (!command.takesArguments && options.rest.isNotEmpty) {
+    command.usageError(
+        'Command "${options.name}" does not take any arguments.');
+  }
+
+  return syncFuture(() {
+    return command.run(cacheDir, options);
+  }).whenComplete(() {
+    command.cache.deleteTempDir();
+  });
+}
+
 /// Checks that pub is running on a supported platform. If it isn't, it prints
 /// an error message and exits. Completes when the validation is done.
 Future validatePlatform() {
   return syncFuture(() {
     if (Platform.operatingSystem != 'windows') return null;
 
     return runProcess('ver', []).then((result) {
       if (result.stdout.join('\n').contains('XP')) {
         log.error('Sorry, but pub is not supported on Windows XP.');
         return flushThenExit(exit_codes.USAGE);
       }
     });
   });
 }