Basic analyzer `main()` isolate bootloader.

lib/src/bootloader.dart

+// Copyright (c) 2015, 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.
+
+library analyzer_cli.src.bootloader;
+
+import 'dart:io';
+import 'dart:isolate';
+
+import 'package:analyzer/file_system/physical_file_system.dart';
+import 'package:analyzer/plugin/options.dart';
+import 'package:analyzer/source/analysis_options_provider.dart';
+import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/plugin/plugin_configuration.dart';
+import 'package:analyzer_cli/src/driver.dart';
+import 'package:analyzer_cli/src/options.dart';
+import 'package:analyzer_cli/src/plugin/plugin_config_processor_plugin.dart';
+import 'package:plugin/manager.dart';
+import 'package:plugin/plugin.dart';
+import 'package:source_span/source_span.dart';
+import 'package:yaml/src/yaml_node.dart';
+
+const _analyzerPackageName = 'analyzer';
+
+/// Source code assembler.
+class Assembler {
+  /// Plugin configuration info.
+  final PluginConfig _config;
+
+  /// Create an assembler for the given plugin [config].
+  Assembler(this._config);
+
+  /// A string enumerating required package `import`s.
+  String get enumerateImports =>
+      plugins.map((PluginInfo p) => "import '${p.libraryUri}';").join('\n');
+
+  /// A string listing initialized plugin instances.
+  String get pluginList =>
+      plugins.map((PluginInfo p) => 'new ${p.className}()').join(', ');
+
+  /// Plugins to configure.
+  List<PluginInfo> get plugins => _config.plugins;
+
+  /// Create a file containing a `main()` suitable for loading in spawned
+  /// isolate.
+  String createMain() => _generateMain();
+
+  String _generateMain() => """
+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// This code was auto-generated, is not intended to be edited, and is subject to
+// significant change. Please see the README file for more information.
+
+import 'package:analyzer_cli/src/driver.dart';
+
+$enumerateImports
+
+void main(List<String> args) {
+  var starter = new Driver();
+  starter.userDefinedPlugins = [$pluginList];
+  starter.start(args);
+}
+""";
+}
+
+/// Given environment information extracted from command-line `args`, creates a
+/// a loadable analyzer "image".
+class BootLoader {
+  /// Emits an error message to [errorSink] if plugin config can't be read.
+  static final ErrorHandler _pluginConfigErrorHandler = (Exception e) {
+    String details;
+    if (e is PluginConfigFormatException) {
+      details = e.message;
+      var node = e.yamlNode;
+      if (node is YamlNode) {
+        SourceLocation location = node.span.start;
+        details += ' (line ${location.line}, column ${location.column})';
+      }
+    } else {
+      details = e.toString();
+    }
+
+    errorSink.writeln('Plugin configuration skipped: $details');
+  };
+
+  /// Reads plugin config info from `.analysis_options`.
+  PluginConfigProcessorPlugin _pluginConfigProcessorPlugin =
+      new PluginConfigProcessorPlugin(_pluginConfigErrorHandler);
+
+  /// Create a loadable analyzer image confifgured with plugins derived from

[Brian Wilkerson, 2015/09/28 17:48:11]

nit: "confifgured" --> "configured"

[pquitslund, 2015/09/28 18:01:29]

Thanks!

+  /// the given analyzer command-line `args`.
+  Image createImage(List<String> args) {
+    _processPlugins();
+
+    // Parse commandline options.
+    CommandLineOptions options = CommandLineOptions.parse(args);
+
+    // Process analysis options file (and notify all interested parties).
+    _processAnalysisOptions(options);
+
+    // TODO(pquitslund): Pass in .packages info
+    return new Image(_pluginConfigProcessorPlugin.pluginConfig,
+        args: args, packageRootPath: options.packageRootPath);
+  }
+
+  void _processAnalysisOptions(CommandLineOptions options) {
+    // Determine options file path.
+    var filePath = options.analysisOptionsFile != null
+        ? options.analysisOptionsFile
+        : AnalysisOptionsProvider.ANALYSIS_OPTIONS_NAME;
+    List<OptionsProcessor> optionsProcessors =

[Brian Wilkerson, 2015/09/28 17:48:11]

I don't think there will be any processors until after we execute the generated
main in the child isolate.

[pquitslund, 2015/09/28 18:01:29]

Actually, that's exactly what our PluginConfigOptionsProcessor is.  If we didn't
add options processors we wouldn't see the plugins configured in
`.analysis_options`.  Side note: if there end up being more plugins that want to
participate in bootstrapping we might want to make this explicit somehow.  In
this case PluginConfigOptionsProcessor should actually ONLY getting run in the
bootstrapping and not in the bootstrapped isolate.  Something to think about...

[Brian Wilkerson, 2015/09/28 18:29:20]

So it's an explicitly installed "plugin" that can only be loaded during the
bootloading process? Doesn't sound much like a plugin, but OK. (I'd probably not
treat it like a plugin just to avoid confusing myself.)
They can't. Not unless we first write a pre-bootloader bootloader that could
discover the plugins that want to run during the bootloading process. That's
just a little too meta for my taste. :-)

[pquitslund, 2015/09/28 21:15:03]

I agree.  Addressed here:

https://codereview.chromium.org/1373903004/
Ha!  We're on the same page.  As much as I like to go meta, this is taking it a
little far. :)

+        AnalysisEngine.instance.optionsPlugin.optionsProcessors;
+    try {
+      var file = PhysicalResourceProvider.INSTANCE.getFile(filePath);
+      AnalysisOptionsProvider analysisOptionsProvider =
+          new AnalysisOptionsProvider();
+      Map<String, YamlNode> options =
+          analysisOptionsProvider.getOptionsFromFile(file);
+      optionsProcessors
+          .forEach((OptionsProcessor p) => p.optionsProcessed(options));
+    } on Exception catch (e) {
+      optionsProcessors.forEach((OptionsProcessor p) => p.onError(e));
+    }
+  }
+
+  void _processPlugins() {
+    List<Plugin> plugins = <Plugin>[];
+    plugins.add(_pluginConfigProcessorPlugin);
+    plugins.addAll(AnalysisEngine.instance.supportedPlugins);
+    ExtensionManager manager = new ExtensionManager();
+    manager.processPlugins(plugins);
+  }
+}
+
+/// A loadable "image" of a a configured analyzer instance.
+class Image {
+  /// (Optional) package root path.
+  final String packageRootPath;
+
+  /// (Optional) package map.
+  final Map<String, Uri> packages;
+
+  /// Args to be passed on to the loaded main.
+  final List<String> args;
+
+  /// Plugin configuration.
+  final PluginConfig config;
+
+  /// Create an image with the given [config] and optionally [packages],
+  /// [packageRootPath], and command line [args].
+  Image(this.config, {this.packages, this.packageRootPath, this.args});
+
+  /// Load this image.
+  ///
+  /// Loading an image consists in assembling an analyzer `main()`, configured
+  /// to include the appropriate analyzer plugins as specified in
+  /// `.analyzer_options` which is then run in a spawned isolate.
+  void load() {
+    String mainSource = new Assembler(config).createMain();
+
+    Uri uri =
+        Uri.parse('data:application/dart;charset=utf-8,${Uri.encodeComponent(
+            mainSource)}');
+
+    ReceivePort errorListener = new ReceivePort();
+    errorListener.listen((data) {
+      //TODO(pquitslund): handle errors.
+      print('>>> ERROR: $data');
+    });
+
+    ReceivePort exitListener = new ReceivePort();
+    exitListener.listen((data) {
+      // Propagate exit code.
+      exit(exitCode);
+    });
+
+    // TODO(pquitslund): update once .packages are supported.
+    String packageRoot =
+        packageRootPath != null ? packageRootPath : './packages';
+    Uri packageUri = new Uri.file(packageRoot);
+
+    // TODO(pquitslund): add .packages support once the VM implements it.
+    Isolate.spawnUri(uri, args, null /* msg */,
+        packageRoot: packageUri,
+        onError: errorListener.sendPort,
+        onExit: exitListener.sendPort);
+
+    // TODO(pquitslund): consider starting paused
+    // http://stackoverflow.com/questions/29247374/what-is-the-best-way-to-track-the-state-of-an-isolate-in-dart
+  }
+}