Support subcommands in pub and pub help.

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

Index: sdk/lib/_internal/pub/bin/pub.dart
diff --git a/sdk/lib/_internal/pub/bin/pub.dart b/sdk/lib/_internal/pub/bin/pub.dart
index a589dcc8403a9ac31593a593ad2afb4545c1f627..ecc8318a9c686ec9342af187b5ab2d87dceb503a 100644
--- a/sdk/lib/_internal/pub/bin/pub.dart
+++ b/sdk/lib/_internal/pub/bin/pub.dart
@@ -7,9 +7,11 @@ 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;
@@ -38,18 +40,6 @@ void main(List<String> arguments) {
     return;
   }
 
-  if (options.command == null) {
-    if (options.rest.isEmpty) {
-      // No command was chosen.
-      PubCommand.printGlobalUsage();
-    } else {
-      log.error('Could not find a command named "${options.rest[0]}".');
-      log.error('Run "pub help" to see available commands.');
-      flushThenExit(exit_codes.USAGE);
-    }
-    return;
-  }
-
   if (options['trace']) {
     log.recordTranscript();
   }
@@ -81,8 +71,125 @@ void main(List<String> arguments) {
     cacheDir = '${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 whose [arguments] have been parsed to
+/// [options] using the system cache in [cacheDir].
+///
+/// Handles and correctly reports any errors that occur while running.
+void runPub(String cacheDir, ArgResults options, List<String> arguments) {
+  var captureStackChains =
+      options['trace'] ||
+      options['verbose'] ||
+      options['verbosity'] == 'all';
+
+  captureErrors(() => invokeCommand(cacheDir, options),
+      captureStackChains: captureStackChains).catchError((error, Chain chain) {
+    // 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));
+  }).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 new Future.value();
+        }
+
+        command.usageError('Missing subcommand for "$commandString".');
+      } else {
+        if (command == null) {
+          PubCommand.usageErrorWithCommands(commands,
+              'Could not find a command named "${options.rest[0]}".');
+        }
+
+        command.usageError('Could not find a subcommand named '
+            '"${options.rest[0]}" for "$commandString".');
+      }
+    }
+
+    // Step into the command.
+    options = options.command;
+    command = commands[options.name];
+    commands = command.subcommands;
+    commandString += " ${options.name}";
+
+    if (options['help']) {
+      command.printUsage();
+      return new Future.value();
+    }
+  }
+
+  // Make sure there aren't unexpected arguments.
+  if (!command.takesArguments && options.rest.isNotEmpty) {
+    command.usageError(
+        'Command "${options.name}" does not take any arguments.');
+  }
+
+  return syncFuture(() {
+    return command.run(cacheDir, options);
+  }).whenComplete(() {
+    command.cache.deleteTempDir();
   });
 }