next step toward completion plugin API

pkg/analysis_server/lib/src/services/completion/dart/reference_contributor.dart

+// Copyright (c) 2014, 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 services.completion.contributor.dart.reference;
+
+import 'dart:async';
+
+import 'package:analysis_server/plugin/protocol/protocol.dart'
+    show CompletionSuggestion, CompletionSuggestionKind;
+import 'package:analysis_server/src/provisional/completion/completion_dart.dart';
+import 'package:analysis_server/src/provisional/completion/dart/completion_target.dart';
+import 'package:analysis_server/src/services/completion/dart_completion_manager.dart'
+    show DART_RELEVANCE_DEFAULT, DART_RELEVANCE_LOCAL_FUNCTION;
+import 'package:analysis_server/src/services/completion/suggestion_builder.dart';
+import 'package:analyzer/src/generated/ast.dart';
+import 'package:analyzer/src/generated/element.dart';
+import 'package:analyzer/src/task/dart.dart';
+import 'package:analyzer/task/model.dart';
+
+/**
+ * A contributor for calculating `completion.getSuggestions` request results
+ * for "free standing" identifiers.
+ */
+class ReferenceContributor extends DartCompletionContributor {
+  @override
+  Future computeSuggestions(
+      DartCompletionRequest request, DartSuggestionCollector collector) {
+    // TODO (danrubel) determine whether references should be suggested
+    // Generate completions outside expressions, method and function bodies
+    return request.resolvedDeclarationTarget
+        .then((CompletionTarget resolvedTarget) {
+      resolvedTarget.unit.element.library.visitChildren(
+          new _ReferenceContributorElemVisitor(collector, true, null));
+    });
+  }
+}
+
+/**
+ * Build suggestions from visited elements.
+ */
+class _ReferenceContributorElemVisitor extends GeneralizingElementVisitor {
+  final DartSuggestionCollector collector;
+  final bool isLocal;
+  final String prefix;
+
+  _ReferenceContributorElemVisitor(this.collector, this.isLocal, this.prefix);
+
+  @override
+  visitCompilationUnitElement(CompilationUnitElement element) {
+    element.visitChildren(this);
+  }
+
+  @override
+  visitFunctionElement(FunctionElement element) {
+    collector.addElementSuggestion(element,
+        includePrivateElements: isLocal,
+        prefix: prefix,
+        relevance:
+            isLocal ? DART_RELEVANCE_LOCAL_FUNCTION : DART_RELEVANCE_DEFAULT);
+  }
+}