new DartCompletionPlugin

pkg/analysis_server/lib/src/provisional/completion/dart/completion_plugin.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 analysis_server.src.provisional.completion.dart.plugin;
+
+import 'package:analysis_server/src/provisional/completion/dart/completion.dart';
+import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
+import 'package:analysis_server/src/services/completion/dart/keyword_contributor.dart';
+import 'package:plugin/plugin.dart';
+
+/**
+ * The shared dart completion plugin instance.
+ */
+final DartCompletionPlugin dartCompletionPlugin = new DartCompletionPlugin();

[Brian Wilkerson, 2015/11/30 18:10:27]

I'm not thrilled about having a global variable, but maybe it's better to be
honest than try to hide it as a static field or even an instance field in a
unique object...

[danrubel, 2015/11/30 18:53:38]

The linter plugin does this as well. If we have a better approach, then we can
apply it there as well.

+
+class DartCompletionPlugin implements Plugin {

[Brian Wilkerson, 2015/11/30 18:10:27]

What's the value of pulling this out to a separate plugin? (I don't have a
strong objection, mostly wanting to know whether the same logic should be
applied elsewhere.)

[danrubel, 2015/11/30 18:53:38]

There will be a top level CompletionContributor extension point. The
DartCompletionManager will be one of several completion contributors (e.g.
AngularCompletionManager, HtmlCompletionManager) which provide their own
extension points. I'm implementing DartCompletionPlugin and
DartCompletionManager along these lines to prove the infrastructure and provide
a pattern for others.

[Brian Wilkerson, 2015/11/30 19:02:01]

I assume that will be in the server plugin, in which case I now understand.

+  /**
+   * The simple identifier of the extension point that allows plugins to
+   * register Dart specific completion contributor factories.
+   * Use [DART_COMPLETION_CONTRIBUTOR_EXTENSION_POINT_ID]
+   * when registering contributors.
+   */
+  static const String CONTRIBUTOR_EXTENSION_POINT = 'contributor';
+
+  /**
+   * The unique identifier of this plugin.
+   */
+  static const String UNIQUE_IDENTIFIER = 'dart.completion';
+
+  /**
+   * The extension point that allows plugins to register Dart specific
+   * completion contributor factories.
+   */
+  ExtensionPoint _contributorExtensionPoint;
+
+  @override
+  String get uniqueIdentifier => UNIQUE_IDENTIFIER;
+
+  /**
+   * Return a list containing all of the Dart specific completion contributor
+   * factories that were contributed.
+   */
+  List<DartCompletionContributorFactory> get contributorFactories =>
+      _contributorExtensionPoint.extensions;
+
+  @override
+  void registerExtensionPoints(RegisterExtensionPoint registerExtensionPoint) {
+    _contributorExtensionPoint = registerExtensionPoint(
+        CONTRIBUTOR_EXTENSION_POINT,
+        _validateDartCompletionContributorExtension);
+  }
+
+  @override
+  void registerExtensions(RegisterExtension registerExtension) {
+    registerExtension(DART_COMPLETION_CONTRIBUTOR_EXTENSION_POINT_ID,
+        () => new KeywordContributor());
+  }
+
+  /**
+   * Validate the given extension by throwing an [ExtensionError] if it is not a
+   * valid Dart specific completion contributor.
+   */
+  void _validateDartCompletionContributorExtension(Object extension) {
+    if (extension is! DartCompletionContributorFactory) {
+      String id = _contributorExtensionPoint.uniqueIdentifier;
+      throw new ExtensionError(
+          'Extensions to $id must be a DartCompletionContributorFactory');
+    }
+  }
+}