Use AnalysisDriverUnlinkedUnit as a container for UnlinkedUnit and referenced names.

pkg/analyzer/lib/src/dart/analysis/file_state.dart

 // Copyright (c) 2016, 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.
 
 import 'dart:convert';
 import 'dart:typed_data';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/dart/analysis/byte_store.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
+import 'package:analyzer/src/dart/analysis/referenced_names.dart';
 import 'package:analyzer/src/dart/scanner/reader.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/parser.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/utilities_dart.dart';
 import 'package:analyzer/src/source/source_resource.dart';
 import 'package:analyzer/src/summary/api_signature.dart';
 import 'package:analyzer/src/summary/format.dart';
 import 'package:analyzer/src/summary/idl.dart';
@@ skipping 54 matching lines @@
   final Uri uri;
 
   /**
    * The [Source] of the file with the [uri].
    */
   Source source;
 
   String _content;
   String _contentHash;
   LineInfo _lineInfo;
+  Set<String> _referencedNames;
   UnlinkedUnit _unlinked;
   List<int> _apiSignature;
 
   List<FileState> _importedFiles;
   List<FileState> _exportedFiles;
   List<FileState> _partedFiles;
   Set<FileState> _directReferencedFiles = new Set<FileState>();
   Set<FileState> _transitiveFiles;
 
   FileState._(this._fsState, this.path, this.uri, this.source);
@@ skipping 55 matching lines @@
    * Return information about line in the file.
    */
   LineInfo get lineInfo => _lineInfo;
 
   /**
    * The list of files this library file references as parts.
    */
   List<FileState> get partedFiles => _partedFiles;
 
   /**
+   * The external names referenced by the file.
+   */
+  Set<String> get referencedNames => _referencedNames;
+
+  /**
    * Return the set of transitive files - the file itself and all of the
    * directly or indirectly referenced files.
    */
   Set<FileState> get transitiveFiles {
     if (_transitiveFiles == null) {
       _transitiveFiles = new Set<FileState>();
 
       void appendReferenced(FileState file) {
         if (_transitiveFiles.add(file)) {
           file._directReferencedFiles.forEach(appendReferenced);
@@ skipping 73 matching lines @@
     }
 
     // Prepare bytes of the unlinked bundle - existing or new.
     List<int> bytes;
     {
       bytes = _fsState._byteStore.get(unlinkedKey);
       if (bytes == null) {
         CompilationUnit unit = parse(AnalysisErrorListener.NULL_LISTENER);
         _fsState._logger.run('Create unlinked for $path', () {
           UnlinkedUnitBuilder unlinkedUnit = serializeAstUnlinked(unit);
-          bytes = unlinkedUnit.toBuffer();
+          List<String> referencedNames = computeReferencedNames(unit).toList();
+          bytes = new AnalysisDriverUnlinkedUnitBuilder(
+                  unit: unlinkedUnit, referencedNames: referencedNames)
+              .toBuffer();
           _fsState._byteStore.put(unlinkedKey, bytes);
         });
       }
     }
 
     // Read the unlinked bundle.
-    _unlinked = new UnlinkedUnit.fromBuffer(bytes);
+    var driverUnlinkedUnit = new AnalysisDriverUnlinkedUnit.fromBuffer(bytes);
+    _referencedNames = new Set<String>.from(driverUnlinkedUnit.referencedNames);

[Brian Wilkerson, 2016/11/21 15:54:37]

This is kind of ugly. Consider adding a getter to AnalysisDriverUnlinkedUnit,
such as referencedNameSet, that would create the set.

[scheglov, 2016/11/21 17:04:54]

We use flat buffers just as data.
Any additional services should be on top of it, not inside of it.
And this is the place where we provide such additional service - quick lookup
for names. 

+    _unlinked = driverUnlinkedUnit.unit;
     _lineInfo = new LineInfo(_unlinked.lineStarts);
     List<int> newApiSignature = _unlinked.apiSignature;
     bool apiSignatureChanged = _apiSignature != null &&
         !_equalByteLists(_apiSignature, newApiSignature);
     _apiSignature = newApiSignature;
 
     // This file is potentially not a library for its previous parts anymore.
     if (_partedFiles != null) {
       for (FileState part in _partedFiles) {
         _fsState._partToLibraries[part]?.remove(this);
@@ skipping 227 matching lines @@
   final FileSystemState state;
 
   FileSystemStateTestView(this.state);
 
   Set<FileState> get filesWithoutTransitive {
     return state._uriToFile.values
         .where((f) => f._transitiveFiles == null)
         .toSet();
   }
 }