Working compiler in browser.

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.
+import 'dart:html' show HttpRequest;
+import 'dart:convert' show BASE64;
+
+import 'package:args/command_runner.dart';
+import 'package:analyzer/src/generated/source.dart'
+    show Source, DartUriResolver;
+import 'package:analyzer/src/summary/idl.dart' show PackageBundle;
+import 'package:dev_compiler/src/compiler/compiler.dart'
+    show BuildUnit, CompilerOptions, JSModuleFile, ModuleCompiler;
+import 'package:dev_compiler/src/analyzer/context.dart' show AnalyzerOptions;
+
+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/context/context.dart' show AnalysisContextImpl;
+import 'package:analyzer/src/context/cache.dart'
+    show AnalysisCache, CachePartition;
+import 'package:analyzer/file_system/memory_file_system.dart'
+    show MemoryResourceProvider;
+import 'package:analyzer/file_system/file_system.dart'
+    show ResourceProvider, ResourceUriResolver;
+import 'package:analyzer/src/summary/summary_sdk.dart' show SummaryBasedDartSdk;
+
+typedef void MessageHandler(Object message);
+
+/// The command for invoking the modular compiler.
+class CompileCommand extends Command {

[Jennifer Messerly, 2016/07/27 21:38:33]

Maybe rename this WebCompileCommand?

[priscillalee, 2016/07/27 23:48:33]

Done.

+  get name => 'compile';
+  get description => 'Compile a set of Dart files into a JavaScript module.';
+  final MessageHandler messageHandler;
+  final Function onload;

[Jennifer Messerly, 2016/07/27 21:38:33]

suggestion, declare a strong type here. `Function` doesn't convey a lot of
information because it allows all signatures. for example:

    typedef void CompileResultFn(String code);
    typedef void CompileFn(String dart, CompileResultFn callback);
    typedef void OnLoadFn(CompileFn compile);

(I'm not sure if those are quite the right signatures, but it's the rough idea)

Another option is to refactor this into async/await. (mentioned below)

[priscillalee, 2016/07/27 23:48:33]

Typedefs are a really good idea! Thanks for that suggestion. Done.

+
+  CompileCommand(this.onload, {MessageHandler messageHandler})
+      : this.messageHandler = messageHandler ?? print {
+    CompilerOptions.addArguments(argParser);
+    AnalyzerOptions.addArguments(argParser);
+  }
+
+  @override
+  String run() {
+    HttpRequest request = new HttpRequest();

[Jennifer Messerly, 2016/07/27 21:38:33]

style: I would probably write this as:

    var request = new HttpRequest();

[priscillalee, 2016/07/27 23:48:33]

Done.

+
+    request.onReadyStateChange.listen((_) {

[Jennifer Messerly, 2016/07/27 21:38:33]

one way to convert this to async/await:


Future<CompileFn> run() async {
  var onLoad = request.onReadyStateChange.first;
  request.open('get', 'dart_sdk.sum');
  request.send();
  await onLoad;
  if (request.readyState ...) {
    ...
    return setUpCompile(sdkBytes);
  }
  return null;
}


Then from the main.dart file, when you call .run:

    var result = await compile.run();
    compileDartExpression = allowInterop(result);

then the "onload" callback wouldn't be needed in this file

[priscillalee, 2016/07/27 23:48:33]

Wow, I love how the async syntax reads, and it'd be really handy here, but I
can't seem to get it working. When I try to "await
request.onReadyStateChange.first", I get 366 errors which all say "type
'EventImpl' is not a subtype of type 'ProgressEvent' of 'value'". I know that an
HttpRequest's onReadyStateChange returns a Stream<ProgressEvent>, but I'm not
sure where the EventImpl is coming from.

[Jennifer Messerly, 2016/07/28 05:23:10]

Ah, maybe not worth worrying about then. Offhand I'm not sure why that would
happen

[priscillalee, 2016/07/28 17:15:52]

Acknowledged.

+      if (request.readyState == HttpRequest.DONE &&
+          (request.status == 200 || request.status == 0)) {
+        var response = request.responseText;
+        var sdkBytes = BASE64.decode(response);
+        Function result = setUpCompile(sdkBytes);
+        onload(result);
+      }
+    });
+
+    request.open('get', 'dart_sdk.sum');
+    request.send();
+
+    return "";
+  }
+
+  Function setUpCompile(List<int> sdkBytes) {

[Jennifer Messerly, 2016/07/27 21:38:33]

would be good to use a typedef for this function type

[priscillalee, 2016/07/27 23:48:33]

Done.

+    var resourceProvider = new MemoryResourceProvider();
+    var packageBundle = new PackageBundle.fromBuffer(sdkBytes);
+    var webDartSdk =
+        new SummaryBasedDartSdk(true, packageBundle, resourceProvider);
+
+    var sdkResolver = new DartUriResolver(webDartSdk);
+    var fileResolvers = [new ResourceUriResolver(resourceProvider)];
+
+    var compiler = new ModuleCompiler(
+        new AnalyzerOptions(dartSdkPath: '/dart-sdk'),
+        sdkResolver: sdkResolver,
+        fileResolvers: fileResolvers,
+        resourceProvider: resourceProvider);
+
+    var compilerOptions = new CompilerOptions.fromArguments(argResults);
+
+    var number = 0;
+
+    return (String dart, Function callback) {
+      //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);
+
+      JSModuleFile module = compiler.compile(unit, compilerOptions);
+      module.errors.forEach(messageHandler);
+
+      if (!module.isValid) throw new CompileErrorException();
+      callback(module.code); //module.summaryBytes;

[Jennifer Messerly, 2016/07/27 21:38:33]

could this be a return value instead of a callback?

[priscillalee, 2016/07/27 23:48:33]

Done.

+    };
+  }
+}
+
+/// Thrown when the input source code has errors.
+class CompileErrorException implements Exception {
+  toString() => '\nPlease fix all errors before compiling (warnings are okay).';
+}
+
+class WebDartSdk implements DartSdk {

[Jennifer Messerly, 2016/07/27 21:38:33]

we didn't end up using this right? So we could delete it

[priscillalee, 2016/07/27 23:48:33]

Done.

+  final Map<Uri, _WebSdkSource> _sources = {};
+  final bool reportMissing;
+  final Map<String, SdkLibrary> _libs = {};
+  final String sdkVersion = '0';
+  List<String> get uris => _sources.keys.map((uri) => '$uri').toList();
+
+  AnalysisContext context;
+  DartUriResolver _resolver;
+  DartUriResolver get resolver => _resolver;
+  PackageBundle packageBundle;
+
+  WebDartSdk(Map<String, String> sources, ResourceProvider resourceProvider,
+      this.packageBundle,
+      {this.reportMissing}) {
+    context = new _SdkAnalysisContext(this);
+    sources.forEach((uriString, contents) {
+      var uri = Uri.parse(uriString);
+      _sources[uri] = new _WebSdkSource(uri, contents);
+      _libs[uriString] = new SdkLibraryImpl(uri.path)
+        ..setDart2JsLibrary()
+        ..setVmLibrary();
+    });
+    _resolver = new DartUriResolver(this);
+
+    context.sourceFactory =
+        new SourceFactory([_resolver], null, resourceProvider);
+  }
+
+  @override
+  PackageBundle getSummarySdkBundle(bool strongMode) {
+    return packageBundle;
+  }
+
+  List<SdkLibrary> get sdkLibraries => _libs.values.toList();
+  SdkLibrary getSdkLibrary(String dartUri) => _libs[dartUri];
+  Source mapDartUri(String dartUri) => _getSource(Uri.parse(dartUri));
+
+  Source fromEncoding(UriKind kind, Uri uri) {
+    if (kind != UriKind.DART_URI) {
+      throw new UnsupportedError('expected dart: uri kind, got $kind.');
+    }
+    return _getSource(uri);
+  }
+
+  Source _getSource(Uri uri) {
+    var src = _sources[uri];
+    if (src == null) {
+      if (reportMissing) print('warning: missing mock for $uri.');
+      _sources[uri] = src = new _WebSdkSource(uri, 'library dart.${uri.path};');
+    }
+    return src;
+  }
+
+  @override
+  Source fromFileUri(Uri uri) {
+    throw new UnsupportedError('WebDartSdk.fromFileUri');
+  }
+}
+
+class _WebSdkSource implements Source {
+  /// Absolute URI which this source can be imported from.
+  final Uri uri;
+  final String _contents;
+
+  _WebSdkSource(this.uri, this._contents);
+
+  bool exists() => true;
+
+  int get hashCode => uri.hashCode;
+
+  final int modificationStamp = 1;
+
+  TimestampedData<String> get contents =>
+      new TimestampedData(modificationStamp, _contents);
+
+  String get encoding => "${uriKind.encoding}$uri";
+
+  Source get source => this;
+
+  String get fullName => shortName;
+
+  String get shortName => uri.path;
+
+  UriKind get uriKind => UriKind.DART_URI;
+
+  bool get isInSystemLibrary => true;
+
+  Source resolveRelative(Uri relativeUri) =>
+      throw new UnsupportedError('not expecting relative urls in dart: mocks');
+
+  Uri resolveRelativeUri(Uri relativeUri) =>
+      throw new UnsupportedError('not expecting relative urls in dart: mocks');
+}
+
+/// An [AnalysisContextImpl] that only contains sources for a Dart SDK.
+class _SdkAnalysisContext extends AnalysisContextImpl {
+  final DartSdk sdk;
+
+  _SdkAnalysisContext(this.sdk);
+
+  @override
+  AnalysisCache createCacheFromSourceFactory(SourceFactory factory) {
+    if (factory == null) {
+      return super.createCacheFromSourceFactory(factory);
+    }
+    return new AnalysisCache(
+        <CachePartition>[AnalysisEngine.instance.partitionManager.forSdk(sdk)]);
+  }
+}