Revert "Start using FileState/FileSystemState to provide consistent view."

pkg/front_end/lib/src/incremental/file_state.dart

Index: pkg/front_end/lib/src/incremental/file_state.dart
diff --git a/pkg/front_end/lib/src/incremental/file_state.dart b/pkg/front_end/lib/src/incremental/file_state.dart
deleted file mode 100644
index fec7c17940977ef7b681a9df3f08231f8a15ab41..0000000000000000000000000000000000000000
--- a/pkg/front_end/lib/src/incremental/file_state.dart
+++ /dev/null
@@ -1,225 +0,0 @@
-// 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 'dart:convert';
-import 'dart:typed_data';
-
-import 'package:front_end/file_system.dart';
-import 'package:front_end/src/fasta/parser/top_level_parser.dart';
-import 'package:front_end/src/fasta/scanner.dart';
-import 'package:front_end/src/fasta/source/directive_listener.dart';
-import 'package:front_end/src/fasta/translate_uri.dart';
-
-/// Information about a file being compiled, explicitly or implicitly.
-///
-/// It provides a consistent view on its properties.
-///
-/// The properties are not guaranteed to represent the most recent state
-/// of the file system. To update the file to the most recent state, [refresh]
-/// should be called.
-class FileState {
-  final FileSystemState _fsState;
-
-  /// The resolved URI of the file in the file system.
-  final Uri fileUri;
-
-  bool _exists;
-  List<int> _contentBytes;
-  String _content;
-
-  List<FileState> _importedFiles;
-  List<FileState> _exportedFiles;
-  List<FileState> _partFiles;
-
-  Set<FileState> _directReferencedFiles = new Set<FileState>();
-
-  FileState._(this._fsState, this.fileUri);
-
-  /// The content of the file.
-  String get content => _content;
-
-  /// The content bytes of the file.
-  List<int> get contentBytes => _contentBytes;
-
-  /// Whether the file exists.
-  bool get exists => _exists;
-
-  @override
-  int get hashCode => fileUri.hashCode;
-
-  /// Return the set of transitive files - the file itself and all of the
-  /// directly or indirectly referenced files.
-  Set<FileState> get transitiveFiles {
-    // TODO(scheglov) add caching.
-    var transitiveFiles = new Set<FileState>();
-
-    void appendReferenced(FileState file) {
-      if (transitiveFiles.add(file)) {
-        file._directReferencedFiles.forEach(appendReferenced);
-      }
-    }
-
-    appendReferenced(this);
-    return transitiveFiles;
-  }
-
-  @override
-  bool operator ==(Object other) {
-    return other is FileState && other.fileUri == fileUri;
-  }
-
-  /// Read the file content and ensure that all of the file properties are
-  /// consistent with the read content, including all its dependencies.
-  Future<Null> refresh() async {
-    // Read the content.
-    try {
-      FileSystemEntity entry = _fsState.fileSystem.entityForUri(fileUri);
-      _contentBytes = await entry.readAsBytes();
-      _content = UTF8.decode(_contentBytes);
-      _exists = true;
-    } catch (_) {
-      _contentBytes = new Uint8List(0);
-      _content = '';
-      _exists = false;
-    }
-
-    // Parse directives.
-    ScannerResult scannerResults = scanString(_content);
-    var listener = new DirectiveListener();
-    new TopLevelParser(listener).parseUnit(scannerResults.tokens);
-
-    // Build the graph.
-    _importedFiles = <FileState>[];
-    _exportedFiles = <FileState>[];
-    _partFiles = <FileState>[];
-    await _addFileForRelativeUri(_importedFiles, 'dart:core');
-    for (String uri in listener.imports) {
-      await _addFileForRelativeUri(_importedFiles, uri);
-    }
-    for (String uri in listener.exports) {
-      await _addFileForRelativeUri(_exportedFiles, uri);
-    }
-    for (String uri in listener.parts) {
-      await _addFileForRelativeUri(_partFiles, uri);
-    }
-
-    // Compute referenced files.
-    _directReferencedFiles = new Set<FileState>()
-      ..addAll(_importedFiles)
-      ..addAll(_exportedFiles)
-      ..addAll(_partFiles);
-  }
-
-  /// Add the [FileState] for the given [relativeUri] to the [files].
-  /// Do nothing if the URI cannot be parsed, cannot correspond any file, etc.
-  Future<Null> _addFileForRelativeUri(
-      List<FileState> files, String relativeUri) async {
-    if (relativeUri.isEmpty) return;
-
-    // Resolve the relative URI into absolute.
-    // The result is either:
-    //   1) The absolute file URI.
-    //   2) The absolute non-file URI, e.g. `package:foo/foo.dart`.
-    Uri absoluteUri;
-    try {
-      absoluteUri = fileUri.resolve(relativeUri);
-    } on FormatException {
-      return;
-    }
-
-    // Resolve the absolute URI into the absolute file URI.
-    Uri resolvedUri = _fsState.uriTranslator.translate(absoluteUri);
-    if (resolvedUri == null) return;
-
-    FileState file = await _fsState.getFile(resolvedUri);
-    files.add(file);
-  }
-}
-
-/// Information about known file system state.
-class FileSystemState {
-  final FileSystem fileSystem;
-  final TranslateUri uriTranslator;
-
-  _FileSystemView _fileSystemView;
-
-  /// Mapping from file URIs to corresponding [FileState]s.
-  final Map<Uri, FileState> _fileUriToFile = {};
-
-  FileSystemState(this.fileSystem, this.uriTranslator);
-
-  /// Return the [FileSystem] that is backed by this [FileSystemState].  The
-  /// files in this [FileSystem] always have the same content as the
-  /// corresponding [FileState]s, thus avoiding race conditions when a file
-  /// is updated on the actual file system.
-  FileSystem get fileSystemView {
-    return _fileSystemView ??= new _FileSystemView(this);
-  }
-
-  /// Return the [FileState] for the given resolved file [fileUri].
-  /// The returned file has the last known state since it was last refreshed.
-  Future<FileState> getFile(Uri fileUri) async {
-    FileState file = _fileUriToFile[fileUri];
-    if (file == null) {
-      file = new FileState._(this, fileUri);
-      _fileUriToFile[fileUri] = file;
-
-      // Build the sub-graph of the file.
-      await file.refresh();
-    }
-    return file;
-  }
-}
-
-/// [FileSystemState] based implementation of [FileSystem].
-/// It provides a consistent view on the known file system state.
-class _FileSystemView implements FileSystem {
-  final FileSystemState fsState;
-
-  _FileSystemView(this.fsState);
-
-  @override
-  FileSystemEntity entityForUri(Uri uri) {
-    FileState file = fsState._fileUriToFile[uri];
-    return new _FileSystemViewEntry(uri, file);
-  }
-}
-
-/// [FileSystemState] based implementation of [FileSystemEntity].
-class _FileSystemViewEntry implements FileSystemEntity {
-  @override
-  final Uri uri;
-
-  final FileState file;
-
-  _FileSystemViewEntry(this.uri, this.file);
-
-  @override
-  Future<bool> exists() async => file?.exists ?? false;
-
-  @override
-  Future<DateTime> lastModified() async {
-    throw new StateError(
-        'FileSystemViewEntry modification stamp should not be queried');
-  }
-
-  @override
-  Future<List<int>> readAsBytes() async {
-    _throwIfDoesNotExist();
-    return file.contentBytes;
-  }
-
-  @override
-  Future<String> readAsString() async {
-    _throwIfDoesNotExist();
-    return file.content;
-  }
-
-  void _throwIfDoesNotExist() {
-    if (file == null) {
-      throw new FileSystemException(uri, 'File $uri does not exist.');
-    }
-  }
-}