Restructured the set up for the compiling function. Also added room for list of additional summarie…

web/web_command.dart

 // Copyright (c) 2016, 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.
+@JS()
+library dev_compiler.web.web_command;
+
 import 'dart:html' show HttpRequest;
 import 'dart:convert' show BASE64;
+import 'dart:async';

[Jacob, 2016/08/03 23:58:32]

sort imports in alphabetical order.

[priscillalee, 2016/08/04 16:01:56]

Done.

 
 import 'package:analyzer/file_system/file_system.dart'
     show ResourceProvider, ResourceUriResolver;
 import 'package:analyzer/file_system/memory_file_system.dart'
     show MemoryResourceProvider;
 import 'package:analyzer/src/context/cache.dart'
     show AnalysisCache, CachePartition;
 import 'package:analyzer/src/context/context.dart' show AnalysisContextImpl;
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisContext, AnalysisEngine, TimestampedData;
 import 'package:analyzer/src/generated/sdk.dart'
     show DartSdk, SdkLibrary, SdkLibraryImpl;
 import 'package:analyzer/src/generated/source.dart'
     show DartUriResolver, Source, SourceFactory, UriKind;
 import 'package:analyzer/src/summary/idl.dart' show PackageBundle;
+import 'package:analyzer/src/summary/package_bundle_reader.dart'
+    show
+        SummaryDataStore,
+        InSummaryPackageUriResolver,
+        InputPackagesResultProvider;
 import 'package:analyzer/src/summary/summary_sdk.dart' show SummaryBasedDartSdk;
 
 import 'package:args/command_runner.dart';
 
 import 'package:dev_compiler/src/analyzer/context.dart' show AnalyzerOptions;
 import 'package:dev_compiler/src/compiler/compiler.dart'
     show BuildUnit, CompilerOptions, JSModuleFile, ModuleCompiler;
 
+import 'package:js/js.dart';
+
 typedef void MessageHandler(Object message);
-typedef String CompileFn(String dart);
-typedef void OnLoadFn(CompileFn compile);
 
 /// The command for invoking the modular compiler.
 class WebCompileCommand extends Command {
   get name => 'compile';
   get description => 'Compile a set of Dart files into a JavaScript module.';
   final MessageHandler messageHandler;
-  final OnLoadFn onload;
 
-  WebCompileCommand(this.onload, {MessageHandler messageHandler})
+  WebCompileCommand({MessageHandler messageHandler})
       : this.messageHandler = messageHandler ?? print {
     CompilerOptions.addArguments(argParser);
     AnalyzerOptions.addArguments(argParser);
   }
 
   @override
-  void run() {
-    var request = new HttpRequest();
-
-    request.onReadyStateChange.listen((_) {
-      if (request.readyState == HttpRequest.DONE &&
-          (request.status == 200 || request.status == 0)) {
-        var response = request.responseText;
-        var sdkBytes = BASE64.decode(response);
-        var result = setUpCompile(sdkBytes);
-        onload(result);
-      }
-    });
-
-    request.open('get', 'dart_sdk.sum');
-    request.send();
+  Function run() {
+    return requestSummaries;

[Jacob, 2016/08/03 23:58:31]

Are we really getting anything from implementing Command? This seems like a
strange pattern given how the code is setup now.

[priscillalee, 2016/08/04 16:01:56]

I agree. It does seem strange. I don't understand how the args or commands are
set up, but I'm mimicking the patterns of bin/dartdevc.dart and
lib/src/compiler/command.dart. I'm not sure how else to structure it.

   }
 
-  CompileFn setUpCompile(List<int> sdkBytes) {
+  void requestSummaries(
+      String sdkUrl, List<String> summaryUrls, Function callback) {
+    HttpRequest.request(sdkUrl).then((sdkRequest) {
+      var sdkResponse = sdkRequest.responseText;
+      var sdkBytes = BASE64.decode(sdkResponse);
+
+      // Map summary URLs to HttpRequests.
+      var summaryRequests = summaryUrls
+          .map((summary) => new Future(() => HttpRequest.request(summary)));
+
+      Future.wait(summaryRequests).then((summaryResponses) {
+        // Map summary responses to summary bytes.
+        var summaryBytes = summaryResponses
+            .map((response) => BASE64.decode(response.responseText));
+
+        var compileFn = setUpCompile(sdkBytes, summaryBytes);
+        callback(compileFn);
+      });

[Jacob, 2016/08/03 23:58:31]

You should handle if a summary fails to load.

[priscillalee, 2016/08/04 16:01:56]

I added status checks, but should I also throw exceptions if a summary fails to
load?

[Jacob, 2016/08/04 16:27:48]

Ideally you would report the error back to the caller so they can display an
appropriate message in the App's UI explaining that something went wrong.
Consider just having the callback the user passes in taking a second argument
that is an error message if compilation or summaries failed.

[priscillalee, 2016/08/04 17:56:33]

Done.

+    });
+  }
+
+  Function setUpCompile(List<int> sdkBytes, List<List<int>> summaryBytes) {
     var resourceProvider = new MemoryResourceProvider();
+    var resourceUriResolver = new ResourceUriResolver(resourceProvider);
+
     var packageBundle = new PackageBundle.fromBuffer(sdkBytes);
     var webDartSdk = new SummaryBasedDartSdk.fromBundle(
         true, packageBundle, resourceProvider);
+    var sdkResolver = new DartUriResolver(webDartSdk);
 
-    var sdkResolver = new DartUriResolver(webDartSdk);
-    var fileResolvers = [new ResourceUriResolver(resourceProvider)];
+    var summaryDataStore = new SummaryDataStore([]);
+    for (var bytes in summaryBytes) {
+      var summaryBundle = new PackageBundle.fromBuffer(bytes);
+      summaryDataStore.addBundle('', summaryBundle);
+    }
+    var summaryResolver = new InSummaryPackageUriResolver(summaryDataStore);
+
+    var fileResolvers = [summaryResolver, resourceUriResolver];
 
     var compiler = new ModuleCompiler(
         new AnalyzerOptions(dartSdkPath: '/dart-sdk'),
         sdkResolver: sdkResolver,
         fileResolvers: fileResolvers,
         resourceProvider: resourceProvider);
 
+    compiler.context.resultProvider =
+        new InputPackagesResultProvider(compiler.context, summaryDataStore);
+
     var compilerOptions = new CompilerOptions.fromArguments(argResults);
 
     var number = 0;
 
-    return (String dart) {
+    var compileFn = (String dart) {
       // Create a new virtual File that contains the given Dart source.
       number++;
       resourceProvider.newFile("/expression$number.dart", dart);
 
-      var unit =
-          new BuildUnit("", "", ["file:///expression$number.dart"], null);
+      var unit = new BuildUnit(
+          "", "", ["file:///expression$number.dart"], (source) => "");

[Jacob, 2016/08/03 23:58:32]

what is the fn (source) => "" doing?
shouldn't it be the string dart?

[Jacob, 2016/08/03 23:58:32]

nit: put {} around number for clarity. 
e.g.
${number}

[priscillalee, 2016/08/04 16:01:56]

It's the libraryToModule function of a BuildUnit. I used to be able to give it
null, but when I started to work with additional summaries, it needed a dummy
function. I haven't come across a point when I've needed it to return a specific
String, so it currently has no use right now. 

[priscillalee, 2016/08/04 16:01:56]

Done.

[Jacob, 2016/08/04 16:27:48]

do that everywhere in the file where $number occurs.

[priscillalee, 2016/08/04 17:56:33]

Done.

 
       JSModuleFile module = compiler.compile(unit, compilerOptions);
       module.errors.forEach(messageHandler);
 
       if (!module.isValid) throw new CompileErrorException();
       return module.code;
     };
+
+    return allowInterop(compileFn);
   }
 }
 
 /// Thrown when the input source code has errors.
 class CompileErrorException implements Exception {
   toString() => '\nPlease fix all errors before compiling (warnings are okay).';
 }