Emit program and dependency information as relations in a Prolog database.

sdk/lib/_internal/compiler/implementation/world.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.
 
 part of dart2js;
 
 class World {
   final Compiler compiler;
   final FunctionSet allFunctions;
   final Set<Element> functionsCalledInLoop = new Set<Element>();
   final Map<Element, SideEffects> sideEffects = new Map<Element, SideEffects>();
 
   final Map<ClassElement, Set<MixinApplicationElement>> mixinUses =
       new Map<ClassElement, Set<MixinApplicationElement>>();
 
+  // TODO(karlklose): remove, this is a subset of the information in
+  // [ClassElement].[allSupertypes].
   final Map<ClassElement, Set<ClassElement>> _typesImplementedBySubclasses =
       new Map<ClassElement, Set<ClassElement>>();
 
-  // We keep track of subtype and subclass relationships in four
+  // We keep track of subtype and subclass relationships in three
   // distinct sets to make class hierarchy analysis faster.
   final Map<ClassElement, Set<ClassElement>> _subclasses =
       new Map<ClassElement, Set<ClassElement>>();
   final Map<ClassElement, Set<ClassElement>> _subtypes =
       new Map<ClassElement, Set<ClassElement>>();
   final Map<ClassElement, Set<ClassElement>> _supertypes =
       new Map<ClassElement, Set<ClassElement>>();
 
   final Set<Element> sideEffectsFreeElements = new Set<Element>();
 
@@ skipping 262 matching lines @@
     // method of function classes that were generated for function
     // expressions. In such a case, we have to look at the original
     // function expressions's element.
     // TODO(herhut): Generate classes for function expressions earlier.
     if (element is closureMapping.SynthesizedCallMethodElementX) {
       return getMightBePassedToApply(element.expression);
     }
     return functionsThatMightBePassedToApply.contains(element);
   }
 }