Lazily initialize library elements.

pkg/compiler/lib/src/compiler.dart

 // Copyright (c) 2012, 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 dart2js.compiler_base;
 
 import 'dart:async' show EventSink, Future;
 
 import '../compiler_new.dart' as api;
 import 'closure.dart' as closureMapping show ClosureTask;
@@ skipping 366 matching lines @@
   /// This method is called when all new libraries loaded through
   /// [LibraryLoader.loadLibrary] has been loaded and their imports/exports
   /// have been computed.
   ///
   /// [loadedLibraries] contains the newly loaded libraries.
   ///
   /// The method returns a [Future] allowing for the loading of additional
   /// libraries.
   LoadedLibraries processLoadedLibraries(LoadedLibraries loadedLibraries) {
     loadedLibraries.forEachLibrary((LibraryElement library) {
-      _commonElements.registerCommonLibraries(library);
       backend.setAnnotations(library);
     });
 
     for (Uri uri in resolvedUriTranslator.disallowedLibraryUris) {
       if (loadedLibraries.containsLibrary(uri)) {
         Set<String> importChains = computeImportChainsFor(loadedLibraries, uri);
         reporter.reportInfo(
             NO_LOCATION_SPANNABLE, MessageKind.DISALLOWED_LIBRARY_IMPORT, {
           'uri': uri,
           'importChain': importChains
@@ skipping 689 matching lines @@
   int warnings = 0;
   int hints = 0;
 }
 
 class _CompilerCommonElements extends CommonElementsMixin {
   final Resolution resolution;
   final DiagnosticReporter reporter;
 
   final ElementEnvironment environment;
 
-  LibraryElement coreLibrary;
-  LibraryElement asyncLibrary;
-  LibraryElement mirrorsLibrary;
-  LibraryElement typedDataLibrary;
-
   _CompilerCommonElements(this.environment, this.resolution, this.reporter);
 
   @override
   ResolutionDynamicType get dynamicType => const ResolutionDynamicType();
 
-  void registerCommonLibraries(LibraryElement library) {
-    Uri uri = library.canonicalUri;
-    if (uri == Uris.dart_core) {
-      coreLibrary = library;
-    } else if (uri == Uris.dart_async) {
-      asyncLibrary = library;
-    } else if (uri == Uris.dart__native_typed_data) {
-      typedDataLibrary = library;
-    } else if (uri == Uris.dart_mirrors) {
-      mirrorsLibrary = library;
-    }
-  }
+  LibraryEntity _coreLibrary;
+  LibraryEntity get coreLibrary =>
+      _coreLibrary ??= environment.lookupLibrary(Uris.dart_core);
+
+  LibraryEntity _typedDataLibrary;
+  LibraryEntity get typedDataLibrary => _typedDataLibrary ??=
+      environment.lookupLibrary(Uris.dart__native_typed_data);
+
+  LibraryEntity _mirrorsLibrary;
+  LibraryEntity get mirrorsLibrary =>
+      _mirrorsLibrary ??= environment.lookupLibrary(Uris.dart_mirrors);
+
+  LibraryEntity _asyncLibrary;
+  LibraryEntity get asyncLibrary =>
+      _asyncLibrary ??= environment.lookupLibrary(Uris.dart_async);
 
   @override
   MemberElement findLibraryMember(LibraryElement library, String name,
       {bool setter: false, bool required: true}) {
     Element member = _findLibraryMember(library, name, required: required);
     if (member != null && member.isAbstractField) {
       AbstractFieldElement abstractField = member;
       if (setter) {
         member = abstractField.setter;
       } else {
@@ skipping 911 matching lines @@
     if (library != null && library.isSynthesized) {
       return null;
     }
     if (library == null && required) {
       throw new SpannableAssertionFailure(
           library, "The library '${uri}' was not found.");
     }
     return library;
   }
 }