OptionsValidator plugin extension and linter service.

pkg/analyzer/lib/plugin/options.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.
 
 /// Support for client code that wants to consume options contributed to the
 /// analysis options file.
 library analyzer.plugin.options;
 
 import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/plugin/options_plugin.dart';
 import 'package:plugin/plugin.dart';
 import 'package:yaml/yaml.dart';
 
 /// The identifier of the extension point that allows plugins to access
 /// options defined in the analysis options file. The object used as an
 /// extension must be an [OptionsProcessor].
 final String OPTIONS_PROCESSOR_EXTENSION_POINT_ID = Plugin.join(
     OptionsPlugin.UNIQUE_IDENTIFIER,
     OptionsPlugin.OPTIONS_PROCESSOR_EXTENSION_POINT);
 
+/// The identifier of the extension point that allows plugins to validate
+/// options defined in the analysis options file. The object used as an
+/// extension must be an [OptionsValidator].
+final String OPTIONS_VALIDATOR_EXTENSION_POINT_ID = Plugin.join(
+    OptionsPlugin.UNIQUE_IDENTIFIER,
+    OptionsPlugin.OPTIONS_VALIDATOR_EXTENSION_POINT);
+
 /// Processes options defined in the analysis options file.
 ///
+/// Clients may implement this class when implementing plugins.
+///
 /// The options file format is intentionally very open-ended, giving clients
 /// utmost flexibility in defining their own options.  The only hardfast
 /// expectation is that options files will contain a mapping from Strings
 /// (identifying 'scopes') to associated options.  For example, the given
 /// content
 ///
 ///     linter:
 ///       rules:
 ///         camel_case_types: true
 ///     compiler:
@@ skipping 21 matching lines @@
   /// The options file is processed on analyzer initialization and
   /// subsequently when the file is changed on disk.  In the event of a
   /// change notification, note that the notification simply indicates
   /// a change on disk. Content in specific option scopes may or may not
   /// be different. It is up to the implementer to check whether specific
   /// options have changed and to handle those changes appropriately. In
   /// addition to the [options] map, the associated analysis [context] is
   /// provided as well to allow for context-specific configuration.
   void optionsProcessed(AnalysisContext context, Map<String, YamlNode> options);
 }
+
+/// Validates options as defined in an analysis options file.
+///
+/// Clients may implement this class when implementing plugins.
+///
+/// See [OptionsProcessor] for a description of the options file format.
+///
+abstract class OptionsValidator {
+  /// Validate [options], reporting any errors to the given [reporter].
+  void validate(ErrorReporter reporter, Map<String, YamlNode> options);
+}