Add support for cross-session storage

pkg/analyzer/lib/file_system/physical_file_system.dart

 // Copyright (c) 2014, 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 physical_file_system;
 
 import 'dart:async';
 import 'dart:io' as io;
 
 import 'package:analyzer/src/generated/java_io.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:path/path.dart';
 import 'package:watcher/watcher.dart';
 
 import 'file_system.dart';
 
 
 /**
  * A `dart:io` based implementation of [ResourceProvider].
  */
 class PhysicalResourceProvider implements ResourceProvider {
   static final PhysicalResourceProvider INSTANCE =
       new PhysicalResourceProvider._();
 
+  /**
+   * The name of the directory containing plugin specific subfolders used to
+   * store data across sessions.
+   */
+  static final String SERVER_DIR = "dartServer";

[Paul Berry, 2014/10/07 16:50:36]

On Mac and Unix it's conventional to name these directories with a leading "."
(e.g. ".pub-cache") so that they are hidden.  I'm not sure what the convention
is on Windows.

[Brian Wilkerson, 2014/10/07 16:57:51]

Done

+
   PhysicalResourceProvider._();
 
   @override
   Context get pathContext => io.Platform.isWindows ? windows : posix;
 
   @override
   Resource getResource(String path) {
     if (io.FileSystemEntity.isDirectorySync(path)) {
       io.Directory directory = new io.Directory(path);
       return new _PhysicalFolder(directory);
     } else {
       io.File file = new io.File(path);
       return new _PhysicalFile(file);
     }
   }
+
+  @override
+  Folder getStateLocation(String pluginId) {
+    String home;
+    if (io.Platform.isWindows) {
+      home = io.Platform.environment['LOCALAPPDATA'];
+    } else {
+      home = io.Platform.environment['HOME'];
+    }
+    if (home != null && io.FileSystemEntity.isDirectorySync(home)) {
+      StringBuffer buffer = new StringBuffer();
+      buffer.write(home);
+      buffer.write(pathContext.separator);
+      buffer.write(SERVER_DIR);
+      buffer.write(pathContext.separator);
+      buffer.write(pluginId);

[Paul Berry, 2014/10/07 16:50:36]

IMHO it reads a lot nicer to construct paths using path.join, e.g.:

  io.Directory directory = new io.Directory(join(home, SERVER_DIR, pluginId));

[Brian Wilkerson, 2014/10/07 16:57:51]

Done

+      io.Directory directory = new io.Directory(buffer.toString());
+      directory.createSync(recursive: true);
+      return new _PhysicalFolder(directory);
+    }
+    return null;
+  }
 }
 
 
 /**
  * A `dart:io` based implementation of [File].
  */
 class _PhysicalFile extends _PhysicalResource implements File {
   _PhysicalFile(io.File file) : super(file);
 
   @override
@@ skipping 98 matching lines @@
   bool operator ==(other) {
     if (runtimeType != other.runtimeType) {
       return false;
     }
     return path == other.path;
   }
 
   @override
   String toString() => path;
 }