Implementation of async-await transformation on js ast.

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 158 matching lines @@
     world.registerStaticUse(element);
   }
 
   void registerDirectInvocation(Element element) {
     world.registerStaticUse(element);
   }
 
   void registerInstantiation(InterfaceType type) {
     world.registerInstantiatedType(type, this);
   }
+
+  void registerAsyncMarker(FunctionElement element) {
+    backend.registerAsyncMarker(element, world, this);
+  }
+
 }
 
 /// [WorkItem] used exclusively by the [CodegenEnqueuer].
 class CodegenWorkItem extends WorkItem {
   Registry registry;
   final TreeElements resolutionTree;
 
   CodegenWorkItem(AstElement element,
                   ItemCompilationContext compilationContext)
       : this.resolutionTree = element.resolvedAst.elements,
@@ skipping 33 matching lines @@
 
   void registerDynamicGetter(Selector selector);
 
   void registerDynamicSetter(Selector selector);
 
   void registerStaticInvocation(Element element);
 
   void registerInstantiation(InterfaceType type);
 
   void registerGetOfStaticFunction(FunctionElement element);
+
+  void registerAsyncMarker(FunctionElement element);
 }
 
 abstract class Backend {
   final Compiler compiler;
 
   Backend(this.compiler);
 
   /// The [ConstantSystem] used to interpret compile-time constants for this
   /// backend.
   ConstantSystem get constantSystem;
@@ skipping 267 matching lines @@
 
   FunctionElement helperForBadMain() => null;
 
   FunctionElement helperForMissingMain() => null;
 
   FunctionElement helperForMainArity() => null;
 
   void forgetElement(Element element) {}
 
   void registerMainHasArguments(Enqueuer enqueuer) {}
+
+  void registerAsyncMarker(FunctionElement element,
+                             Enqueuer enqueuer,
+                             Registry registry) {}
 }
 
 /// Backend callbacks function specific to the resolution phase.
 class ResolutionCallbacks {
   /// Register that [node] is a call to `assert`.
   void onAssert(Send node, Registry registry) {}
 
   /// Called during resolution to notify to the backend that the
   /// program uses string interpolation.
   void onStringInterpolation(Registry registry) {}
@@ skipping 204 matching lines @@
   /// `true` if the last diagnostic was filtered, in which case the
   /// accompanying info message should be filtered as well.
   bool lastDiagnosticWasFiltered = false;
 
   /// Map containing information about the warnings and hints that have been
   /// suppressed for each library.
   Map<Uri, SuppressionInfo> suppressedWarnings = <Uri, SuppressionInfo>{};
 
   final bool suppressWarnings;
 
-  /// `true` if async/await features are supported.
-  final bool enableAsyncAwait;
-
-  /// `true` if the compiler uses the [JavaScriptBackend].
-  final bool emitJavaScript;
-
   /// If `true`, some values are cached for reuse in incremental compilation.
   /// Incremental compilation is basically calling [run] more than once.
   final bool hasIncrementalSupport;
 
   /// If `true` native extension syntax is supported by the frontend.
   final bool allowNativeExtensions;
 
   /// Output provider from user of Compiler API.
   api.CompilerOutputProvider userOutputProvider;
 
   /// Generate output even when there are compile-time errors.
   final bool generateCodeWithCompileTimeErrors;
 
   bool disableInlining = false;
 
   List<Uri> librariesToAnalyzeWhenRun;
 
   Tracer tracer;
 
   CompilerTask measuredTask;
   Element _currentElement;
   LibraryElement coreLibrary;
+  LibraryElement asyncLibrary;
 
   LibraryElement mainApp;
   FunctionElement mainFunction;
 
   /// Initialized when dart:mirrors is loaded.
   LibraryElement mirrorsLibrary;
 
   /// Initialized when dart:typed_data is loaded.
   LibraryElement typedDataLibrary;
 
@@ skipping 219 matching lines @@
             this.outputUri: null,
             this.buildId: UNDETERMINED_BUILD_ID,
             this.terseDiagnostics: false,
             this.deferredMapUri: null,
             this.dumpInfo: false,
             this.showPackageWarnings: false,
             this.useContentSecurityPolicy: false,
             this.suppressWarnings: false,
             bool hasIncrementalSupport: false,
             this.enableExperimentalMirrors: false,
-            bool enableAsyncAwait: false,
             this.allowNativeExtensions: false,
             this.generateCodeWithCompileTimeErrors: false,
             api.CompilerOutputProvider outputProvider,
             List<String> strips: const []})
-      : this.emitJavaScript = emitJavaScript,
-        this.enableAsyncAwait = enableAsyncAwait || !emitJavaScript,
-        this.disableTypeInferenceFlag =
+      : 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)
             ? NullSink.outputProvider
             : outputProvider {
@@ skipping 207 matching lines @@
     Uri uri = library.canonicalUri;
     if (uri == DART_CORE) {
       initializeCoreClasses();
       identicalFunction = coreLibrary.find('identical');
     } else if (uri == DART_INTERNAL) {
       symbolImplementationClass = findRequiredElement(library, 'Symbol');
     } else if (uri == DART_MIRRORS) {
       mirrorSystemClass = findRequiredElement(library, 'MirrorSystem');
       mirrorsUsedClass = findRequiredElement(library, 'MirrorsUsed');
     } else if (uri == DART_ASYNC) {
+      asyncLibrary = library;
       deferredLibraryClass = findRequiredElement(library, 'DeferredLibrary');
       _coreTypes.futureClass = findRequiredElement(library, 'Future');
       _coreTypes.streamClass = findRequiredElement(library, 'Stream');
     } else if (uri == DART_NATIVE_TYPED_DATA) {
       typedDataClass = findRequiredElement(library, 'NativeTypedData');
     } else if (uri == js_backend.JavaScriptBackend.DART_JS_HELPER) {
       patchAnnotationClass = findRequiredElement(library, '_Patch');
       nativeAnnotationClass = findRequiredElement(library, 'Native');
     }
     return backend.onLibraryScanned(library, loader);
@@ skipping 1152 matching lines @@
     return futureClass.computeType(compiler).createInstantiation([elementType]);
   }
 
   @override
   InterfaceType streamType([DartType elementType = const DynamicType()]) {
     return streamClass.computeType(compiler).createInstantiation([elementType]);
   }
 }
 
 typedef void InternalErrorFunction(Spannable location, String message);