Optimize top-level element declarations search.

pkg/analysis_server/lib/src/services/search/search_engine_internal.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.src.search.search_engine;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/services/index/index.dart';
 import 'package:analysis_server/src/services/search/search_engine.dart';
@@ skipping 85 matching lines @@
   Future<List<SearchMatch>> searchSubtypes(ClassElement type) {
     _Requestor requestor = new _Requestor(_index);
     requestor.add(type, IndexConstants.IS_EXTENDED_BY, MatchKind.REFERENCE);
     requestor.add(type, IndexConstants.IS_MIXED_IN_BY, MatchKind.REFERENCE);
     requestor.add(type, IndexConstants.IS_IMPLEMENTED_BY, MatchKind.REFERENCE);
     return requestor.merge();
   }
 
   @override
   Future<List<SearchMatch>> searchTopLevelDeclarations(String pattern) {
-    UniverseElement universe = UniverseElement.INSTANCE;
-    _Requestor requestor = new _Requestor(_index);
-    requestor.add(universe, IndexConstants.DEFINES, MatchKind.DECLARATION);
     RegExp regExp = new RegExp(pattern);
-    return requestor.merge().then((List<SearchMatch> matches) {
-      return matches.where((SearchMatch match) {
-        String name = match.element.displayName;
-        return regExp.hasMatch(name);
-      }).toList();
-    });
+    List<Element> elements = _index.getTopLevelDeclarations((String name) => regExp.hasMatch(name));
+    List<SearchMatch> matches = <SearchMatch>[];
+    for (var element in elements) {
+      SourceRange range = new SourceRange(element.nameOffset, element.name.length);
+      matches.add(new SearchMatch(MatchKind.DECLARATION, element, range, true, false));
+    }
+    // TODO(scheglov) it does not have to be a Future
+    return new Future.value(matches);
   }
 
   Future<List<SearchMatch>> _searchReferences(Element element) {
     _Requestor requestor = new _Requestor(_index);
     requestor.add(
         element,
         IndexConstants.IS_REFERENCED_BY,
         MatchKind.REFERENCE);
     return requestor.merge();
   }
@@ skipping 108 matching lines @@
     });
     futures.add(matchesFuture);
   }
 
   Future<List<SearchMatch>> merge() {
     return Future.wait(futures).then((List<List<SearchMatch>> matchesList) {
       return matchesList.expand((matches) => matches).toList();
     });
   }
 }