Various caches for incremental compilation.

dart/sdk/lib/_internal/compiler/implementation/native_handler.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 native;
 
 import 'dart:collection' show Queue;
 import 'dart2jslib.dart';
 import 'dart_types.dart';
 import 'elements/elements.dart';
@@ skipping 72 matching lines @@
   /**
    * The set of all native classes.  Each native class is in [nativeClasses] and
    * exactly one of [unusedClasses], [pendingClasses] and [registeredClasses].
    */
   final Set<ClassElement> nativeClasses = new Set<ClassElement>();
 
   final Set<ClassElement> registeredClasses = new Set<ClassElement>();
   final Set<ClassElement> pendingClasses = new Set<ClassElement>();
   final Set<ClassElement> unusedClasses = new Set<ClassElement>();
 
+  final Set<LibraryElement> processedLibraries =
+      new Set<LibraryElement>.identity();
+
   bool hasInstantiatedNativeClasses() => !registeredClasses.isEmpty;
 
   final Set<ClassElement> nativeClassesAndSubclasses = new Set<ClassElement>();
 
   final Map<ClassElement, Set<ClassElement>> nonNativeSubclasses =
       new Map<ClassElement, Set<ClassElement>>();
 
   /**
    * Records matched constraints ([SpecialType] or [DartType]).  Once a type
    * constraint has been matched, there is no need to match it again.
@@ skipping 14 matching lines @@
   final bool enableLiveTypeAnalysis;
 
   ClassElement _annotationCreatesClass;
   ClassElement _annotationReturnsClass;
   ClassElement _annotationJsNameClass;
 
   /// Subclasses of [NativeEnqueuerBase] are constructed by the backend.
   NativeEnqueuerBase(this.world, this.compiler, this.enableLiveTypeAnalysis);
 
   void processNativeClasses(Iterable<LibraryElement> libraries) {
+    if (compiler.hasIncrementalSupport) {
+      libraries = libraries.where((library) => processedLibraries.add(library));

[floitsch, 2014/06/19 12:00:24]

where(processedLibraries.add)

It's ok without, but I would remind the reader what `add` returns.

[ahe, 2014/06/19 13:50:10]

Done.
Agreed.

+    }
     libraries.forEach(processNativeClassesInLibrary);
     if (compiler.isolateHelperLibrary != null) {
       processNativeClassesInLibrary(compiler.isolateHelperLibrary);
     }
     processSubclassesOfNativeClasses(libraries);
     if (!enableLiveTypeAnalysis) {
       nativeClasses.forEach((c) => enqueueClass(c, 'forced'));
       flushQueue();
     }
   }
@@ skipping 1045 matching lines @@
     LiteralString jsCode = nativeBody.asLiteralString();
     builder.push(new HForeign.statement(
         js.js.statementTemplateYielding(
             new js.LiteralStatement(jsCode.dartString.slowToString())),
         <HInstruction>[],
         new SideEffects(),
         null,
         backend.dynamicType));
   }
 }