Options plugin API.

pkg/analyzer/lib/plugin/options.dart

Index: pkg/analyzer/lib/plugin/options.dart
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+// 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/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);
+
+/// Processes options defined in the analysis options file.
+/// 
+/// 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:
+///       resolver:
+///         useMultiPackage: true
+///       packagePaths:
+///         - /foo/bar/pkg
+///         - /bar/baz/pkg
+///
+/// defines two scopes, `linter` and `compiler`.  Parsing would result in a
+/// map, mapping the `linter` and `compiler` scope identifiers to their
+/// respective parsed option node contents. Extracting values is a simple
+/// matter of inspecting the parsed nodes.  For example, testing whether the
+/// compiler's resolver is set to use the `useMultiPackage` option might look
+/// something like this (eliding error-checking):
+///
+///     bool useMultiPackage =
+///         options['compiler']['resolver']['useMultiPackage'];
+abstract class OptionsProcessor {
+
+  /// Called when an error occurs in processing options.
+  void onError(Exception exception);
+
+  /// Called when the options file is processed.
+  ///
+  /// 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.
+  void optionsProcessed(Map<String, YamlNode> options);
+}