Parameterize backend

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.
 
 part of dart2js;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 531 matching lines @@
 
   FunctionElement helperForMainArity() => null;
 
   void forgetElement(Element element) {}
 
   void registerMainHasArguments(Enqueuer enqueuer) {}
 
   void registerAsyncMarker(FunctionElement element,
                              Enqueuer enqueuer,
                              Registry registry) {}
+
+  EnqueueTask makeEnqueuer() => new EnqueueTask(compiler);
 }
 
 /// Backend callbacks function specific to the resolution phase.
 class ResolutionCallbacks {
   /// Register that [node] is a call to `assert`.
   void onAssert(Send node, Registry registry) {}
 
   /// Register that an 'await for' has been seen.
   void onAsyncForIn(AsyncForIn node, Registry registry) {}
 
@@ skipping 497 matching lines @@
             bool useStartupEmitter: false,
             this.useContentSecurityPolicy: false,
             this.suppressWarnings: false,
             this.fatalWarnings: false,
             bool hasIncrementalSupport: false,
             this.enableExperimentalMirrors: false,
             this.allowNativeExtensions: false,
             this.generateCodeWithCompileTimeErrors: false,
             this.testMode: false,
             api.CompilerOutput outputProvider,
-            List<String> strips: const []})
+            List<String> strips: const [],
+            Backend makeBackend(Compiler compiler)})
       : this.disableTypeInferenceFlag =
           disableTypeInferenceFlag || !emitJavaScript,
         this.analyzeOnly =
             analyzeOnly || analyzeSignaturesOnly || analyzeAllFlag,
         this.analyzeSignaturesOnly = analyzeSignaturesOnly,
         this.analyzeAllFlag = analyzeAllFlag,
         this.hasIncrementalSupport = hasIncrementalSupport,
         cacheStrategy = new CacheStrategy(hasIncrementalSupport),
         this.userOutputProvider = outputProvider == null
             ? const NullCompilerOutput() : outputProvider {
@@ skipping 11 matching lines @@
 
     if (verbose) {
       progress = new Stopwatch()..start();
     }
 
     // TODO(johnniwinther): Separate the dependency tracking from the enqueuing
     // for global dependencies.
     globalDependencies =
         new CodegenRegistry(this, new TreeElementMapping(null));
 
-    if (emitJavaScript) {
+    if (makeBackend != null) {
+      backend = makeBackend(this);
+    } else if (emitJavaScript) {
       js_backend.JavaScriptBackend jsBackend =
           new js_backend.JavaScriptBackend(
               this, generateSourceMap: generateSourceMap,
               useStartupEmitter: useStartupEmitter);
       backend = jsBackend;
     } else {
       backend = new dart_backend.DartBackend(this, strips,
                                              multiFile: dart2dartMultiFile);
       if (dumpInfo) {
         throw new ArgumentError('--dump-info is not supported for dart2dart.');
       }
     }
 
     tasks = [
       libraryLoader = new LibraryLoaderTask(this),
       serialization = new SerializationTask(this),
       scanner = new ScannerTask(this),
       dietParser = new DietParserTask(this),
       parser = new ParserTask(this),
       patchParser = new PatchParserTask(this),
       resolver = new ResolverTask(this, backend.constantCompilerTask),
       closureToClassMapper = new closureMapping.ClosureTask(this),
       checker = new TypeCheckerTask(this),
       irBuilder = new IrBuilderTask(this, backend.sourceInformationStrategy),
       typesTask = new ti.TypesTask(this),
       constants = backend.constantCompilerTask,
       deferredLoadTask = new DeferredLoadTask(this),
       mirrorUsageAnalyzerTask = new MirrorUsageAnalyzerTask(this),
-      enqueuer = new EnqueueTask(this),
+      enqueuer = backend.makeEnqueuer(),
       dumpInfoTask = new DumpInfoTask(this),
       reuseLibraryTask = new GenericTask('Reuse library', this),
     ];
 
     tasks.addAll(backend.tasks);
   }
 
   Universe get resolverWorld => enqueuer.resolution.universe;
   Universe get codegenWorld => enqueuer.codegen.universe;
 
@@ skipping 1371 matching lines @@
   InterfaceType streamType([DartType elementType]) {
     InterfaceType type = streamClass.computeType(compiler);
     if (elementType == null) {
       return streamClass.rawType;
     }
     return type.createInstantiation([elementType]);
   }
 }
 
 typedef void InternalErrorFunction(Spannable location, String message);