Roll Observatory packages and add a roll script

package_config/lib/src/packages_impl.dart

-// Copyright (c) 2015, 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.
-
-/// Implementations of [Packages] that may be used in either server or browser
-/// based applications. For implementations that can only run in the browser,
-/// see [package_config.packages_io_impl].
-library package_config.packages_impl;
-
-import "dart:collection" show UnmodifiableMapView;
-import "../packages.dart";
-import "util.dart" show checkValidPackageUri;
-
-/// A [Packages] null-object.
-class NoPackages implements Packages {
-  const NoPackages();
-
-  Uri resolve(Uri packageUri, {Uri notFound(Uri packageUri)}) {
-    String packageName = checkValidPackageUri(packageUri);
-    if (notFound != null) return notFound(packageUri);
-    throw new ArgumentError.value(packageUri, "packageUri",
-                                  'No package named "$packageName"');
-  }
-
-  Iterable<String> get packages => new Iterable<String>.generate(0);
-
-  Map<String, Uri> asMap() => const<String,Uri>{};
-}
-
-/// Base class for [Packages] implementations.
-///
-/// This class implements the [resolve] method in terms of a private
-/// member
-abstract class PackagesBase implements Packages {
-  Uri resolve(Uri packageUri, {Uri notFound(Uri packageUri)}) {
-    packageUri = _normalizePath(packageUri);
-    String packageName = checkValidPackageUri(packageUri);
-    Uri packageBase = getBase(packageName);
-    if (packageBase == null) {
-      if (notFound != null) return notFound(packageUri);
-      throw new ArgumentError.value(packageUri, "packageUri",
-                                    'No package named "$packageName"');
-    }
-    String packagePath = packageUri.path.substring(packageName.length + 1);
-    return packageBase.resolve(packagePath);
-  }
-
-  /// Find a base location for a package name.
-  ///
-  /// Returns `null` if no package exists with that name, and that can be
-  /// determined.
-  Uri getBase(String packageName);
-
-  // TODO: inline to uri.normalizePath() when we move to 1.11
-  static Uri _normalizePath(Uri uri) => new Uri().resolveUri(uri);
-}
-
-/// A [Packages] implementation based on an existing map.
-class MapPackages extends PackagesBase {
-  final Map<String, Uri> _mapping;
-  MapPackages(this._mapping);
-
-  Uri getBase(String packageName) => _mapping[packageName];
-
-  Iterable<String> get packages => _mapping.keys;
-
-  Map<String, Uri> asMap() => new UnmodifiableMapView<String, Uri>(_mapping);
-}
-
-/// A [Packages] implementation based on a remote (e.g., HTTP) directory.
-///
-/// There is no way to detect which packages exist short of trying to use
-/// them. You can't necessarily check whether a directory exists,
-/// except by checking for a know file in the directory.
-class NonFilePackagesDirectoryPackages extends PackagesBase {
-  final Uri _packageBase;
-  NonFilePackagesDirectoryPackages(this._packageBase);
-
-  Uri getBase(String packageName) => _packageBase.resolve("$packageName/");
-
-  Error _failListingPackages() {
-    return new UnsupportedError(
-        "Cannot list packages for a ${_packageBase.scheme}: "
-        "based package root");
-  }
-
-  Iterable<String> get packages {
-    throw _failListingPackages();
-  }
-
-  Map<String, Uri> asMap() {
-    throw _failListingPackages();
-  }
-}