Extract ClosedWorldImpl from WorldImpl.

pkg/compiler/lib/src/universe/function_set.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 universe.function_set;
 
 import '../common/names.dart' show Identifiers, Selectors;
 import '../compiler.dart' show Compiler;
 import '../elements/elements.dart';
 import '../types/types.dart';
 import '../util/util.dart' show Hashing, Setlet;
 import '../world.dart' show ClosedWorld;
 import 'selector.dart' show Selector;
 import 'world_builder.dart' show ReceiverConstraint;
 
-// TODO(kasperl): This actually holds getters and setters just fine
-// too and stricly they aren't functions. Maybe this needs a better
-// name -- something like ElementSet seems a bit too generic.
-class FunctionSet {
-  final ClosedWorld closedWorld;
+class FunctionSetBuilder {
   final Map<String, FunctionSetNode> nodes = new Map<String, FunctionSetNode>();
-  FunctionSet(this.closedWorld);
 
   FunctionSetNode newNode(String name) => new FunctionSetNode(name);
 
   void add(Element element) {
     assert(element.isInstanceMember);
     assert(!element.isAbstract);
     String name = element.name;
     FunctionSetNode node = nodes.putIfAbsent(name, () => newNode(name));
     node.add(element);
   }
 
   void remove(Element element) {
     assert(element.isInstanceMember);
     assert(!element.isAbstract);
     String name = element.name;
     FunctionSetNode node = nodes[name];
     if (node != null) {
       node.remove(element);
     }
   }
 
+  FunctionSet close(ClosedWorld closedWorld) {
+    return new FunctionSet(closedWorld, nodes);
+  }
+}
+
+// TODO(kasperl): This actually holds getters and setters just fine
+// too and stricly they aren't functions. Maybe this needs a better
+// name -- something like ElementSet seems a bit too generic.
+class FunctionSet {
+  final ClosedWorld closedWorld;
+  final Map<String, FunctionSetNode> nodes;
+
+  FunctionSet(this.closedWorld, this.nodes);
+
   bool contains(Element element) {
     assert(element.isInstanceMember);
     assert(!element.isAbstract);
     String name = element.name;
     FunctionSetNode node = nodes[name];
     return (node != null) ? node.contains(element) : false;
   }
 
   /// Returns all the functions that may be invoked with the [selector] on a
   /// receiver with the given [constraint]. The returned elements may include
@@ skipping 238 matching lines @@
           } else if (closedWorld.isInstantiated(cls.declaration)) {
             return new TypeMask.nonNullSubclass(cls.declaration, closedWorld);
           } else {
             // TODO(johnniwinther): Avoid the need for this case.
             return const TypeMask.empty();
           }
         }),
         closedWorld);
   }
 }