Optimize top-level element declarations search.

pkg/analysis_server/lib/src/services/index/index.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.index;
 
 import 'dart:async';
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/html.dart';
 import 'package:analyzer/src/generated/source.dart';
 
 
 /**
+ * A filter for [Element] names.
+ */
+typedef bool ElementNameFilter(String name);
+
+
+/**
  * The interface [Index] defines the behavior of objects that maintain an index
  * storing relations between [Element]s.
  *
  * Any modification operations are executed before any read operation.
  * There is no guarantee about the order in which the [Future]s for read
  * operations will complete.
  */
 abstract class Index {
   /**
    * Answers index statistics.
@@ skipping 16 matching lines @@
    * [element] - the element that has the relationship with the locations to be
    * returned.
    *
    * [relationship] - the relationship between the given element and the
    * locations to be returned.
    */
   Future<List<Location>> getRelationships(Element element,
       Relationship relationship);
 
   /**
+   * Returns top-level [Element]s whose names satisfy to [nameFilter].
+   */
+  List<Element> getTopLevelDeclarations(ElementNameFilter nameFilter);
+
+  /**
    * Processes the given [HtmlUnit] in order to record the relationships.
    *
    * [context] - the [AnalysisContext] in which [HtmlUnit] was resolved.
    * [unit] - the [HtmlUnit] being indexed.
    */
   void indexHtmlUnit(AnalysisContext context, HtmlUnit unit);
 
   /**
    * Processes the given [CompilationUnit] in order to record the relationships.
    *
@@ skipping 287 matching lines @@
    */
   static Relationship getRelationship(String identifier) {
     Relationship relationship = _RELATIONSHIP_MAP[identifier];
     if (relationship == null) {
       relationship = new Relationship(identifier);
       _RELATIONSHIP_MAP[identifier] = relationship;
     }
     return relationship;
   }
 }
-
-
-/**
- * An element to use when we want to request "defines" relations without
- * specifying an exact library.
- */
-class UniverseElement extends ElementImpl {
-  static final UniverseElement INSTANCE = new UniverseElement._();
-
-  UniverseElement._() : super("--universe--", -1);
-
-  @override
-  ElementKind get kind => ElementKind.UNIVERSE;
-
-  @override
-  accept(ElementVisitor visitor) => null;
-}