first cut cmdline analysis server launcher

pkg/analysis_server/bin/dartdeps.dart

+// Copyright (c) 2014, 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:analysis_server/src/analysis_manager.dart';
+
+/**
+ * Start analysis server as a separate process and use the websocket protocol
+ * to analyze the application specified on the command line.
+ */
+void main(List<String> args) {
+  _DartDependencyAnalyzer analyzer = new _DartDependencyAnalyzer();
+  analyzer.start(args);
+}
+
+/**
+ * Instances of [_DartDependencyAnalyzer] launch an analysis server and use
+ * that server to analyze the dependencies of an application.
+ */
+class _DartDependencyAnalyzer {

[Brian Wilkerson, 2014/02/21 15:09:54]

Style question: In analysis server I put the private classes into a private
library (as public classes) and imported them. I'm not sure which is better, but
I don't like reading underscores and my approach allowed me to remove them
without exposing them as public API. I'd be interested in your thoughts.

[danrubel, 2014/02/21 15:51:13]

I made it private and kept it in this library because
1) it is tightly coupled with the main method
2) it should not be reused by any other internal or external library
3) it keeps the code together

+  /**
+   * The name of the application that is used to start the analyzer.
+   */
+  static const BINARY_NAME = 'dartdeps';

[Brian Wilkerson, 2014/02/21 15:09:54]

I thought I remembered that the application was going to analyze dependencies
between packages and was therefore going to be named "pkgdeps". But if you like
this better, I'm not objecting.

[danrubel, 2014/02/21 15:51:13]

I like "dartdeps" because this is more the just showing package dependencies,
but I'm happy to change it if there is something better.

+
+  /**
+   * The name of the option used to print usage information.
+   */
+  static const String HELP_OPTION = "help";
+
+  /**
+   * Parse the command line arguments to determine the application to be
+   * analyzed, then launch and manage an analysis server to do the work.
+   * If there is a problem with the given arguments, then return a non zero
+   * value, otherwise return zero.
+   */
+  void start(List<String> args) {
+    var parser = new ArgParser();
+    parser.addFlag(HELP_OPTION, help:
+        "print this help message without starting analysis", defaultsTo: false,
+        negatable: false);
+
+    // Parse arguments
+    ArgResults results = parser.parse(args);
+    if (results[HELP_OPTION]) {
+      _printUsage(parser);
+      return;
+    }
+    if (results.rest.length == 0) {
+      _printUsage(parser);
+      exitCode = 1;
+      return;
+    }
+    Directory appDir = new Directory(results.rest[0]);
+    if (!appDir.existsSync()) {
+      print('Specified application directory does not exist: $appDir');
+      print('');
+      _printUsage(parser);
+      exitCode = 1;
+      return;
+    }
+    if (results.rest.length > 1) {
+      print('Unexpected arguments after $appDir');
+      print('');
+      _printUsage(parser);
+      exitCode = 1;
+      return;
+    }
+
+    // Assume that the analysis server entry point is in the same directory
+    StringBuffer path = new StringBuffer();
+    path.write(FileSystemEntity.parentOf(Platform.script.toFilePath()));
+    path.write(Platform.pathSeparator);
+    path.write("server.dart");
+
+    // Launch analysis server
+    AnalysisManager.start(path.toString()).then(_analyze);
+  }
+
+  void _analyze(AnalysisManager mgr) {

[Brian Wilkerson, 2014/02/21 15:09:54]

Style question: Is there any value in marking an instance method as being
private when it is defined in a private class? Unless you return an instance of
this class somewhere then no-one can ever invoke this method anyway.

[danrubel, 2014/02/21 15:51:13]

Good point! Removed _

+    print("Analyzing...");
+    new Timer(new Duration(seconds: 5), () {
+      if (mgr.stop()) {
+        print("stopped");
+      } else {
+        print("already stopped");
+      }
+    });
+  }
+
+  /**
+   * Print information about how to use the server.
+   */
+  void _printUsage(ArgParser parser) {
+    print('Usage: $BINARY_NAME [flags] <application_directory>');
+    print('');
+    print('Supported flags are:');
+    print(parser.getUsage());
+  }
+}