Implement a replacement for FileBasedSource (and _MemoryFileSource)

pkg/analyzer/lib/src/source/source_resource.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.
+
+library analyzer.src.source.source_resource;
+
+import 'dart:collection';
+
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/generated/source.dart';
+
+/**
+ * A source that represents a file.
+ */
+class FileSource extends Source {
+  /**
+   * A function that changes the way that files are read off of disk.
+   */
+  static Function fileReadMode = (String s) => s;
+
+  /**
+   * Map from encoded URI/filepath pair to a unique integer identifier.  This
+   * identifier is used for equality tests and hash codes.
+   *
+   * The URI and filepath are joined into a pair by separating them with an '@'
+   * character.
+   */
+  static final Map<String, int> _idTable = new HashMap<String, int>();
+
+  /**
+   * The URI from which this source was originally derived.
+   */
+  @override
+  final Uri uri;
+
+  /**
+   * The unique ID associated with this [FileBasedSource].
+   */
+  final int id;
+
+  /**
+   * The file represented by this source.
+   */
+  final File file;
+
+  /**
+   * The cached absolute path of this source.
+   */
+  String _absolutePath;
+
+  /**
+   * The cached encoding for this source.
+   */
+  String _encoding;
+
+  /**
+   * Initialize a newly created source object to represent the given [file]. If
+   * a [uri] is given, then it will be used as the URI from which the source was
+   * derived, otherwise a `file:` URI will be created based on the [file].
+   */
+  FileSource(File file, [Uri uri])
+      : this.uri = uri ?? file.toUri(),
+        this.file = file,
+        id = _idTable.putIfAbsent(
+            '${uri ?? file.toUri()}@${file.path}', () => _idTable.length);
+
+  @override
+  TimestampedData<String> get contents {
+    return PerformanceStatistics.io.makeCurrentWhile(() {
+      return contentsFromFile;
+    });
+  }
+
+  /**
+   * Get the contents and timestamp of the underlying file.
+   *
+   * Clients should consider using the method [AnalysisContext.getContents]
+   * because contexts can have local overrides of the content of a source that the source is not
+   * aware of.
+   *
+   * @return the contents of the source paired with the modification stamp of the source
+   * @throws Exception if the contents of this source could not be accessed
+   * See [contents].
+   */
+  TimestampedData<String> get contentsFromFile {
+    return new TimestampedData<String>(
+        file.modificationStamp, fileReadMode(file.readAsStringSync()));
+  }
+
+  @override
+  String get encoding {
+    if (_encoding == null) {
+      _encoding = uri.toString();

[scheglov, 2016/08/16 00:54:26]

This can be simplified with ??=.

[Brian Wilkerson, 2016/08/16 13:21:28]

done

+    }
+    return _encoding;
+  }
+
+  @override
+  String get fullName {
+    if (_absolutePath == null) {
+      _absolutePath = file.path;

[scheglov, 2016/08/16 00:54:26]

This can be simplified with ??=.

[Brian Wilkerson, 2016/08/16 13:21:28]

done

+    }
+    return _absolutePath;
+  }
+
+  @override
+  int get hashCode => id;
+
+  @override
+  bool get isInSystemLibrary => uri.scheme == DartUriResolver.DART_SCHEME;
+
+  @override
+  int get modificationStamp => file.modificationStamp;
+
+  @override
+  String get shortName => file.shortName;
+
+  @override
+  UriKind get uriKind => UriKind.fromScheme(uri.scheme);
+
+  @override
+  bool operator ==(Object object) {
+    if (object is FileSource) {
+      return id == object.id;
+    } else if (object is Source) {
+      return uri == object.uri;
+    }
+    return false;
+  }
+
+  @override
+  bool exists() => file.exists;
+
+  @override
+  String toString() {
+    if (file == null) {
+      return "<unknown source>";
+    }
+    return file.path;
+  }
+}