A strawman for an extensible Linter API

angular_linter_plugin.dart

import 'dart:async';

import 'package:angular2/metadata.dart';
import 'package:linter/isolate.dart';

Future<Null> main(SendPort sendPort) {
  // Create a new 'Isolate'-based plugin to the linter.
  final plugin = await registerPlugin(sendPort, new PluginOptions(
    // To avoid serializing/deserializing needlessly, support a basic
    // regular expression-based filter to check a file for before
    // sending anything over the wire.
    filter: '/@Component|@Directive/',
  ));
  // Finally, run the linter.
  await plugin.run(new AngularDartLinter());
}

class AngularDartLinter extends LinterPlugin {
  // Everytime a file should be linted, this should be called.
  @override
  Future<Null> visitFile(CompilationUnit compilationUnit) {
    // Search for `@Component` and `@Directive`s in compilationUnit.
    // When found, call the respective function below.
    return visitAnnotatedNodes(
      compilationUnit, {
      Component: visitComponent,
      Directive: visitDirective,
    });
  }
  
  Future<Null> visitComponent(Component metadata, {SourceSpan source}) async {
    // An example of a lint, we are missing a template.
    if (metadata.template == null && metadata.templateUrl == null) {
      addLint(
        LintType.ERROR, 
        'An @Component must have either a template or templateUrl',
        source: source,
      );
    }
  }
}