Get rid of RootSource.

utils/pub/entrypoint.dart

 // Copyright (c) 2012, 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 entrypoint;
 
 import 'dart:async';
 import 'io.dart';
 import 'lock_file.dart';
 import 'log.dart' as log;
 import 'package.dart';
-import 'root_source.dart';
 import 'system_cache.dart';
 import 'utils.dart';
 import 'version.dart';
 import 'version_solver.dart';
 
 /// Pub operates over a directed graph of dependencies that starts at a root
 /// "entrypoint" package. This is typically the package where the current
 /// working directory is located. An entrypoint knows the [root] package it is
 /// associated with and is responsible for managing the "packages" directory
 /// for it.
@@ skipping 102 matching lines @@
       }
       return versionSolver.solve();
     }).then(_installDependencies);
   }
 
   /// Removes the old packages directory, installs all dependencies listed in
   /// [packageVersions], and writes a [LockFile].
   Future _installDependencies(List<PackageId> packageVersions) {
     return cleanDir(path).then((_) {
       return Future.wait(packageVersions.mappedBy((id) {
-        if (id.source is RootSource) return new Future.immediate(id);
+        if (id.isRoot) return new Future.immediate(id);
         return install(id);
       }));
     }).then(_saveLockFile)
       .then(_installSelfReference)
       .then(_linkSecondaryPackageDirs);
   }
 
   /// Loads the list of concrete package versions from the `pubspec.lock`, if it
   /// exists. If it doesn't, this completes to an empty [LockFile].
   Future<LockFile> loadLockFile() {
     var lockFilePath = join(root.dir, 'pubspec.lock');
 
     log.fine("Loading lockfile.");
     return fileExists(lockFilePath).then((exists) {
       if (!exists) {
         log.fine("No lock file at $lockFilePath, creating empty one.");
         return new LockFile.empty();
       }
 
       return readTextFile(lockFilePath).then((text) =>
           new LockFile.parse(text, cache.sources));
     });
   }
 
   /// Saves a list of concrete package versions to the `pubspec.lock` file.
   Future _saveLockFile(List<PackageId> packageIds) {
     var lockFile = new LockFile.empty();
     for (var id in packageIds) {
-      if (id.source is! RootSource) lockFile.packages[id.name] = id;
+      if (!id.isRoot) lockFile.packages[id.name] = id;
     }
 
     var lockFilePath = join(root.dir, 'pubspec.lock');
     log.fine("Saving lockfile.");
     return writeTextFile(lockFilePath, lockFile.serialize());
   }
 
   /// Installs a self-referential symlink in the `packages` directory that will
   /// allow a package to import its own files using `package:`.
   Future _installSelfReference(_) {
@@ skipping 64 matching lines @@
 
   /// Creates a symlink to the `packages` directory in [dir] if none exists.
   Future _linkSecondaryPackageDir(String dir) {
     var to = join(dir, 'packages');
     return exists(to).then((exists) {
       if (exists) return;
       return createSymlink(path, to);
     });
   }
 }