Flutter run with machine output (#6645)

* add flutter run --machine flag
* refactor daemon stdin/out command stream/response
* extract daemon startApp method
* refactor flutter run --machine to call daemon.startApp

packages/flutter_tools/lib/src/commands/daemon.dart

@@ -52,31 +52,14 @@ class DaemonCommand extends FlutterCommand {
     Cache.releaseLockEarly();
 
     return appContext.runInZone(() {
-      Stream<Map<String, dynamic>> commandStream = stdin
-        .transform(UTF8.decoder)
-        .transform(const LineSplitter())
-        .where((String line) => line.startsWith('[{') && line.endsWith('}]'))
-        .map((String line) {
-          line = line.substring(1, line.length - 1);
-          return JSON.decode(line);
-        });
-
-      Daemon daemon = new Daemon(commandStream, (Map<String, dynamic> command) {
-        stdout.writeln('[${JSON.encode(command, toEncodable: _jsonEncodeObject)}]');
-      }, daemonCommand: this, notifyingLogger: notifyingLogger);
+      Daemon daemon = new Daemon(
+          stdinCommandStream, stdoutCommandResponse,
+          daemonCommand: this, notifyingLogger: notifyingLogger);
 
       return daemon.onExit;
     }, onError: _handleError);
   }
 
-  dynamic _jsonEncodeObject(dynamic object) {
-    if (object is Device)
-      return _deviceToMap(object);
-    if (object is OperationResult)
-      return _operationResultToMap(object);
-    return object;
-  }
-
   dynamic _handleError(dynamic error, StackTrace stackTrace) {
     printError('Error from flutter daemon: $error', stackTrace);
     return null;
@@ -306,6 +289,23 @@ class AppDomain extends Domain {
       throw "'$projectDirectory' does not exist";
 
     BuildMode buildMode = getBuildModeForName(mode) ?? BuildMode.debug;
+
+    AppInstance app = startApp(
+        device, projectDirectory, target, route,
+        buildMode, startPaused, enableHotReload);
+
+    return <String, dynamic>{
+      'appId': app.id,
+      'deviceId': device.id,
+      'directory': projectDirectory,
+      'supportsRestart': isRestartSupported(enableHotReload, device)
+    };
+  }
+
+  AppInstance startApp(
+      Device device, String projectDirectory, String target, String route,
+      BuildMode buildMode, bool startPaused, bool enableHotReload) {
+
     DebuggingOptions options;
 
     switch (buildMode) {
@@ -342,14 +342,12 @@ class AppDomain extends Domain {
       );
     }
 
-    bool supportsRestart = enableHotReload ? device.supportsHotMode : device.supportsRestart;
-
     AppInstance app = new AppInstance(_getNewAppId(), runner);
     _apps.add(app);
     _sendAppEvent(app, 'start', <String, dynamic>{
-      'deviceId': deviceId,
+      'deviceId': device.id,
       'directory': projectDirectory,
-      'supportsRestart': supportsRestart
+      'supportsRestart': isRestartSupported(enableHotReload, device)
     });
 
     Completer<DebugConnectionInfo> connectionInfoCompleter;
@@ -375,14 +373,12 @@ class AppDomain extends Domain {
       });
     });
 
-    return <String, dynamic>{
-      'appId': app.id,
-      'deviceId': deviceId,
-      'directory': projectDirectory,
-      'supportsRestart': supportsRestart
-    };
+    return app;
   }
 
+  bool isRestartSupported(bool enableHotReload, Device device) =>
+      enableHotReload ? device.supportsHotMode : device.supportsRestart;
+
   Future<OperationResult> restart(Map<String, dynamic> args) async {
     String appId = _getStringArg(args, 'appId', required: true);
     bool fullRestart = _getBoolArg(args, 'fullRestart') ?? false;
@@ -561,6 +557,27 @@ class DeviceDomain extends Domain {
   }
 }
 
+Stream<Map<String, dynamic>> get stdinCommandStream => stdin
+  .transform(UTF8.decoder)
+  .transform(const LineSplitter())
+  .where((String line) => line.startsWith('[{') && line.endsWith('}]'))
+  .map((String line) {
+    line = line.substring(1, line.length - 1);
+    return JSON.decode(line);
+  });
+
+void stdoutCommandResponse(Map<String, dynamic> command) {
+  stdout.writeln('[${JSON.encode(command, toEncodable: _jsonEncodeObject)}]');
+}
+
+dynamic _jsonEncodeObject(dynamic object) {
+  if (object is Device)
+    return _deviceToMap(object);
+  if (object is OperationResult)
+    return _operationResultToMap(object);
+  return object;
+}
+
 Map<String, dynamic> _deviceToMap(Device device) {
   return <String, dynamic>{
     'id': device.id,

packages/flutter_tools/lib/src/commands/run.dart

@@ -19,6 +19,7 @@ import '../resident_runner.dart';
 import '../run.dart';
 import '../runner/flutter_command.dart';
 import 'build_apk.dart';
+import 'daemon.dart';
 import 'install.dart';
 import 'trace.dart';
 
@@ -61,6 +62,10 @@ class RunCommand extends RunCommandBase {
     argParser.addOption('use-application-binary',
         hide: !verboseHelp,
         help: 'Specify a pre-built application binary to use when running.');
+    argParser.addFlag('machine',
+        hide: !verboseHelp,
+        help: 'Handle machine structured JSON command input\n'
+              'and provide output and progress in machine friendly format.');
     usesPubOption();
 
     // Option to enable hot reloading.
@@ -79,7 +84,6 @@ class RunCommand extends RunCommandBase {
             'and SIGUSR2 to trigger a full restart.'
     );
 
-
     // Hidden option to enable a benchmarking mode. This will run the given
     // application, measure the startup time and the app restart time, write the
     // results out to 'refresh_benchmark.json', and exit. This flag is intended
@@ -153,8 +157,23 @@ class RunCommand extends RunCommandBase {
 
   @override
   Future<int> runCommand() async {
-    int debugPort;
 
+    Cache.releaseLockEarly();
+
+    // Enable hot mode by default if `--no-hot` was not passed and we are in
+    // debug mode.
+    final bool hotMode = shouldUseHotMode();
+
+    if (argResults['machine']) {
+      Daemon daemon = new Daemon(stdinCommandStream, stdoutCommandResponse,
+          notifyingLogger: new NotifyingLogger());
+      AppInstance app = daemon.appDomain.startApp(
+        device, Directory.current.path, targetFile, route,
+        getBuildMode(), argResults['start-paused'], hotMode);
+      return app.runner.waitForAppToFinish();
+    }
+
+    int debugPort;
     if (argResults['debug-port'] != null) {
       try {
         debugPort = int.parse(argResults['debug-port']);
@@ -181,12 +200,6 @@ class RunCommand extends RunCommandBase {
       );
     }
 
-    Cache.releaseLockEarly();
-
-    // Enable hot mode by default if ``--no-hot` was not passed and we are in
-    // debug mode.
-    final bool hotMode = shouldUseHotMode();
-
     if (hotMode) {
       if (!device.supportsHotMode) {
         printError('Hot mode is not supported by this device. '
@@ -207,7 +220,7 @@ class RunCommand extends RunCommandBase {
         device,
         target: targetFile,
         debuggingOptions: options,
-        benchmarkMode: argResults['benchmark'],
+        benchmarkMode: argResults['benchmark']
       );
     } else {
       runner = new RunAndStayResident(