Work in progress: front end hot reload API

pkg/front_end/lib/src/incremental_resolved_ast_generator_impl.dart

+// Copyright (c) 2017, 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:async';
+
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/src/context/context.dart';
+import 'package:analyzer/src/dart/analysis/byte_store.dart';
+import 'package:analyzer/src/dart/analysis/driver.dart' as driver;
+import 'package:analyzer/src/dart/analysis/file_state.dart';
+import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/generated/sdk.dart';
+import 'package:analyzer/src/generated/source.dart';
+import 'package:analyzer/src/summary/idl.dart';
+import 'package:analyzer/src/summary/summary_sdk.dart';
+import 'package:analyzer/src/util/absolute_path.dart';
+import 'package:front_end/incremental_resolved_ast_generator.dart';
+import 'package:front_end/src/base/processed_options.dart';
+import 'package:front_end/src/base/source.dart';
+import 'package:front_end/src/dependency_grapher_impl.dart';
+import 'package:path/src/context.dart';
+
+dynamic unimplemented() {
+  // TODO(paulberry): get rid of this.
+  throw new UnimplementedError();
+}
+
+/// Implementation of [IncrementalKernelGenerator].
+///
+/// Theory of operation: this class is a thin wrapper around
+/// [driver.AnalysisDriver].  When the client requests a new delta, we forward
+/// the request to the analysis driver.  When the client calls an invalidate
+/// method, we ensure that the proper files will be re-read next time a delta is
+/// requested.
+///
+/// Note that the analysis driver expects to be able to read file contents
+/// synchronously based on filesystem path rather than asynchronously based on
+/// URI, so the file contents are first read into memory using the asynchronous
+/// FileSystem API, and then these are fed into the analysis driver using a
+/// proxy implementation of [ResourceProvider].  TODO(paulberry): make this (and
+/// other proxies in this file) unnecessary.
+class IncrementalResolvedAstGeneratorImpl
+    implements IncrementalResolvedAstGenerator {
+  driver.AnalysisDriverScheduler _scheduler;
+  final _pathToUriMap = <String, Uri>{};
+  final _uriToPathMap = <Uri, String>{};
+  final _fileContents = <String, String>{};
+  _ResourceProviderProxy _resourceProvider;
+  driver.AnalysisDriver _driver;
+  bool _isInitialized = false;
+  final ProcessedOptions _options;
+  final Uri _source;
+
+  IncrementalResolvedAstGeneratorImpl(this._source, this._options);
+
+  @override
+  Future<DeltaLibraries> computeDelta() async {
+    if (!_isInitialized) {
+      await init();
+    }
+    // The analysis driver doesn't currently support an asynchronous file API,
+    // so we have to find all the files first to read their contents.
+    // TODO(paulberry): this is an unnecessary source of duplicate work and
+    // should be eliminated ASAP.
+    var graph = await graphForProgram([_source], _options);
+    var libraries = <Uri, ResolvedLibrary>{};
+    // TODO(paulberry): it should be possible to seed the driver using a URI,
+    // not a file path.
+    // TODO(paulberry): only start the scheduler the first time.
+    _scheduler.start();
+    _driver.addFile(_source.path);
+    for (var libraryCycle in graph.topologicallySortedCycles) {
+      for (var uri in libraryCycle.libraries.keys) {
+        var contents =
+            await _options.fileSystem.entityForUri(uri).readAsString();
+        _storeVirtualFile(uri, uri.path, contents);
+      }
+      // The driver will request files from dart:, even though it actually uses
+      // the data from the summary.  TODO(paulberry): fix this.
+      _storeVirtualFile(_DartSdkProxy._dartCoreSource.uri, 'core.dart', '');
+      for (var uri in libraryCycle.libraries.keys) {
+        var result = await _driver.getResult(uri.path);
+        // TODO(paulberry): handle errors.
+        libraries[uri] = new ResolvedLibrary(result.unit);
+      }
+    }
+    // TODO(paulberry): stop the scheduler
+    return new DeltaLibraries(libraries);
+  }
+
+  Future<Null> init() async {
+    // TODO(paulberry): can we just use null?
+    var performanceLog = new driver.PerformanceLog(new _NullStringSink());
+    _scheduler = new driver.AnalysisDriverScheduler(performanceLog);
+    _resourceProvider =
+        new _ResourceProviderProxy(_fileContents, _pathToUriMap);
+    // TODO(paulberry): MemoryByteStore leaks memory (it never discards data).
+    // Do something better here.
+    var byteStore = new MemoryByteStore();
+    // TODO(paulberry): can we just use null?
+    var fileContentOverlay = new FileContentOverlay();
+    var sdkContext = new AnalysisContextImpl();
+    var dartSdk = new _DartSdkProxy(await _options.getSdkSummary(), sdkContext);
+    sdkContext.sourceFactory =
+        new SourceFactory([new DartUriResolver(dartSdk)]);
+    bool strongMode = true; // TODO(paulberry): support strong mode flag.
+    sdkContext.resultProvider = new SdkSummaryResultProvider(
+        sdkContext, await _options.getSdkSummary(), strongMode);
+
+    var sourceFactory =
+        new _SourceFactoryProxy(dartSdk, _pathToUriMap, _uriToPathMap);
+    var analysisOptions = new AnalysisOptionsImpl();
+    _driver = new driver.AnalysisDriver(
+        _scheduler,
+        performanceLog,
+        _resourceProvider,
+        byteStore,
+        fileContentOverlay,
+        sourceFactory,
+        analysisOptions);
+    _isInitialized = true;
+  }
+
+  @override
+  void invalidate(String path) {
+    throw new UnimplementedError();
+  }
+
+  @override
+  void invalidateAll() {
+    throw new UnimplementedError();
+  }
+
+  void _storeVirtualFile(Uri uri, String path, String contents) {
+    _pathToUriMap[path] = uri;
+    _uriToPathMap[uri] = path;
+    _fileContents[path] = contents;
+  }
+}
+
+class _DartSdkProxy implements DartSdk {
+  static final _dartCoreSource =
+      new _SourceProxy(Uri.parse('dart:core'), 'core.dart');
+
+  final PackageBundle summary;
+
+  final AnalysisContext context;
+
+  _DartSdkProxy(this.summary, this.context);
+
+  @override
+  PackageBundle getLinkedBundle() => summary;
+
+  @override
+  Source mapDartUri(String uri) {
+    // TODO(paulberry): this seems hacky.
+    return new _SourceProxy(Uri.parse(uri), '$uri.dart');
+  }
+
+  noSuchMethod(Invocation invocation) => unimplemented();
+}
+
+class _FileProxy implements File {
+  final _SourceProxy _source;
+
+  final _ResourceProviderProxy _resourceProvider;
+
+  _FileProxy(this._source, this._resourceProvider);
+
+  @override
+  String get path => _source.fullName;
+
+  @override
+  String get shortName => path;
+
+  @override
+  Source createSource([Uri uri]) {
+    assert(uri == null);
+    return _source;
+  }
+
+  noSuchMethod(Invocation invocation) => unimplemented();
+
+  @override
+  String readAsStringSync() {
+    assert(_resourceProvider.fileContents.containsKey(path));
+    return _resourceProvider.fileContents[path];
+  }
+}
+
+/// A string sink that ignores everything written to it.
+class _NullStringSink implements StringSink {
+  void write(Object obj) {}
+  void writeAll(Iterable objects, [String separator = ""]) {}
+  void writeCharCode(int charCode) {}
+  void writeln([Object obj = ""]) {}
+}
+
+class _ResourceProviderProxy implements ResourceProvider {
+  final Map<String, String> fileContents;
+  final Map<String, Uri> pathToUriMap;
+
+  _ResourceProviderProxy(this.fileContents, this.pathToUriMap);
+
+  @override
+  AbsolutePathContext get absolutePathContext => throw new UnimplementedError();
+
+  @override
+  Context get pathContext => throw new UnimplementedError();
+
+  @override
+  File getFile(String path) {
+    assert(fileContents.containsKey(path));
+    assert(pathToUriMap.containsKey(path));
+    return new _FileProxy(new _SourceProxy(pathToUriMap[path], path), this);
+  }
+
+  @override
+  Folder getFolder(String path) => throw new UnimplementedError();
+
+  @override
+  Future<List<int>> getModificationTimes(List<Source> sources) =>
+      throw new UnimplementedError();
+
+  @override
+  Resource getResource(String path) => throw new UnimplementedError();
+
+  @override
+  Folder getStateLocation(String pluginId) => throw new UnimplementedError();
+}
+
+class _SourceFactoryProxy implements SourceFactory {
+  @override
+  final DartSdk dartSdk;
+
+  final Map<String, Uri> pathToUriMap;
+
+  final Map<Uri, String> uriToPathMap;
+
+  @override
+  AnalysisContext context;
+
+  _SourceFactoryProxy(this.dartSdk, this.pathToUriMap, this.uriToPathMap);
+
+  @override
+  SourceFactory clone() => this;
+
+  @override
+  Source forUri(String absoluteUri) {
+    if (absoluteUri == 'dart:core') return _DartSdkProxy._dartCoreSource;
+    Uri uri = Uri.parse(absoluteUri);
+    assert(uriToPathMap.containsKey(uri));
+    return new _SourceProxy(uri, uriToPathMap[uri]);
+  }
+
+  noSuchMethod(Invocation invocation) => unimplemented();
+
+  Source resolveUri(Source containingSource, String containedUri) {
+    // TODO(paulberry): re-use code from dependency_grapher_impl, and support
+    // SDK URI resolution logic.
+    var absoluteUri = containingSource.uri.resolve(containedUri);
+    return forUri(absoluteUri.toString());
+  }
+
+  @override
+  Uri restoreUri(Source source) => source.uri;
+}
+
+class _SourceProxy extends BasicSource {
+  @override
+  final String fullName;
+
+  _SourceProxy(Uri uri, this.fullName) : super(uri);
+
+  int get modificationStamp => 0;
+
+  noSuchMethod(Invocation invocation) => unimplemented();
+}