Implement library access restrictions and privacy.

pkg/front_end/lib/src/fasta/builder/class_builder.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.
 
 library fasta.class_builder;
 
 import '../errors.dart' show internalError;
 
 import 'builder.dart'
     show
@@ skipping 57 matching lines @@
 
   LibraryBuilder get library {
     LibraryBuilder library = parent;
     return library.partOfLibrary ?? library;
   }
 
   @override
   int resolveConstructors(LibraryBuilder library) {
     if (constructorReferences == null) return 0;
     for (ConstructorReferenceBuilder ref in constructorReferences) {
-      ref.resolveIn(scope);
+      ref.resolveIn(scope, library);
     }
     return constructorReferences.length;
   }
 
   /// Used to lookup a static member of this class.
-  Builder findStaticBuilder(String name, int charOffset, Uri fileUri,
+  Builder findStaticBuilder(
+      String name, int charOffset, Uri fileUri, LibraryBuilder accessingLibrary,
       {bool isSetter: false}) {
+    if (accessingLibrary != library && name.startsWith("_")) return null;
     Builder builder = isSetter
         ? scope.lookupSetter(name, charOffset, fileUri, isInstanceScope: false)
         : scope.lookup(name, charOffset, fileUri, isInstanceScope: false);
     return builder;
   }
 
-  Builder findConstructorOrFactory(String name, int charOffset, Uri uri) {
+  Builder findConstructorOrFactory(
+      String name, int charOffset, Uri uri, LibraryBuilder accessingLibrary) {
+    if (accessingLibrary != library && name.startsWith("_")) return null;
     return constructors.lookup(name, charOffset, uri);
   }
 
   /// Returns a map which maps the type variables of [superclass] to their
   /// respective values as defined by the superclass clause of this class (and
   /// its superclasses).
   ///
   /// It's assumed that [superclass] is a superclass of this class.
   ///
   /// For example, given:
@@ skipping 91 matching lines @@
   }
 
   void addWarning(int charOffset, String message) {
     library.addWarning(charOffset, message, fileUri: fileUri);
   }
 
   void addNit(int charOffset, String message) {
     library.addNit(charOffset, message, fileUri: fileUri);
   }
 }