Rename several classes in barback.

pkg/barback/lib/src/package_graph.dart

 // Copyright (c) 2013, 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 barback.asset_graph_manager;
+library barback.package_graph;
 
 import 'dart:async';
 
 import 'package:stack_trace/stack_trace.dart';
 
 import 'asset.dart';
-import 'asset_provider.dart';
-import 'asset_graph.dart';
+import 'asset_cascade.dart';
 import 'asset_id.dart';
 import 'errors.dart';
+import 'package_provider.dart';
 import 'utils.dart';
 
-// TODO(nweiz): come up with better names for this and AssetGraph.
+/// The collection of [AssetCascade]s for an entire application.
+///
+/// This tracks each package's [AssetCascade] and routes asset requests between
+/// them.
+class PackageGraph {
+  /// The provider that exposes asset and package information.
+  final PackageProvider provider;
 
-/// The asset manager for an entire application.
-///
-/// This tracks each package's [AssetGraph] and routes asset requests between
-/// them.
-class AssetGraphManager {
-  /// The provider that exposes asset and package information.
-  final AssetProvider provider;
+  /// The [AssetCascade] for each package.
+  final _cascades = <String, AssetCascade>{};
 
-  /// The [AssetGraph] for each package.
-  final _graphs = <String, AssetGraph>{};
-
-  /// The current [BuildResult] for each package's [AssetGraph].
+  /// The current [BuildResult] for each package's [AssetCascade].
   ///
-  /// The result for a given package will be `null` if that [AssetGraph] is
+  /// The result for a given package will be `null` if that [AssetCascade] is
   /// actively building.
-  final _graphResults = <String, BuildResult>{};
+  final _cascadeResults = <String, BuildResult>{};
 
   /// A stream that emits a [BuildResult] each time the build is completed,
   /// whether or not it succeeded.
   ///
-  /// This will emit a result only once every package's [AssetGraph] has
+  /// This will emit a result only once every package's [AssetCascade] has
   /// finished building.
   ///
   /// If an unexpected error in barback itself occurs, it will be emitted
   /// through this stream's error channel.
   Stream<BuildResult> get results => _resultsController.stream;
   final _resultsController = new StreamController<BuildResult>.broadcast();
 
-  /// A stream that emits any errors from the asset graph or the transformers.
+  /// A stream that emits any errors from the graph or the transformers.
   ///
   /// This emits errors as they're detected. If an error occurs in one part of
-  /// the asset graph, unrelated parts will continue building.
+  /// the graph, unrelated parts will continue building.
   ///
   /// This will not emit programming errors from barback itself. Those will be
   /// emitted through the [results] stream's error channel.
   Stream get errors => _errors;
   Stream _errors;
 
-  /// Creates a new [AssetGraphManager] that will transform assets in all
-  /// packages made available by [provider].
-  AssetGraphManager(this.provider) {
+  /// Creates a new [PackageGraph] that will transform assets in all packages
+  /// made available by [provider].
+  PackageGraph(this.provider) {
     for (var package in provider.packages) {
-      var graph = new AssetGraph(this, package,
+      var cascade = new AssetCascade(this, package,
           provider.getTransformers(package));
-      // The initial result for each graph is "success" since the graph doesn't
-      // start building until some source in that graph is updated.
-      _graphResults[package] = new BuildResult.success();
-      _graphs[package] = graph;
+      // The initial result for each cascade is "success" since the cascade
+      // doesn't start building until some source in that graph is updated.
+      _cascadeResults[package] = new BuildResult.success();
+      _cascades[package] = cascade;
 
-      graph.results.listen((result) {
-        _graphResults[graph.package] = result;
-        // If any graph hasn't yet finished, the overall build isn't finished
+      cascade.results.listen((result) {
+        _cascadeResults[cascade.package] = result;
+        // If any cascade hasn't yet finished, the overall build isn't finished
         // either.
-        if (_graphResults.values.any((result) => result == null)) return;
+        if (_cascadeResults.values.any((result) => result == null)) return;
 
-        // Include all build errors for all graphs. If no graphs have errors,
-        // the result will automatically be considered a success.
+        // Include all build errors for all cascades. If no cascades have
+        // errors, the result will automatically be considered a success.
         _resultsController.add(new BuildResult(flatten(
-            _graphResults.values.map((result) => result.errors))));
+            _cascadeResults.values.map((result) => result.errors))));
       }, onError: _resultsController.addError);
     }
 
-    _errors = mergeStreams(_graphs.values.map((graph) => graph.errors));
+    _errors = mergeStreams(_cascades.values.map((cascade) => cascade.errors));
   }
 
   /// Gets the asset identified by [id].
   ///
   /// If [id] is for a generated or transformed asset, this will wait until
   /// it has been created and return it. If the asset cannot be found, throws
   /// [AssetNotFoundException].
   Future<Asset> getAssetById(AssetId id) {
-    var graph = _graphs[id.package];
-    if (graph != null) return graph.getAssetById(id);
+    var cascade = _cascades[id.package];
+    if (cascade != null) return cascade.getAssetById(id);
     return new Future.error(
         new AssetNotFoundException(id),
         new Trace.current().vmTrace);
   }
 
   /// Adds [sources] to the graph's known set of source assets.
   ///
   /// Begins applying any transforms that can consume any of the sources. If a
   /// given source is already known, it is considered modified and all
   /// transforms that use it will be re-applied.
   void updateSources(Iterable<AssetId> sources) {
     groupBy(sources, (id) => id.package).forEach((package, ids) {
-      var graph = _graphs[package];
-      if (graph == null) throw new ArgumentError("Unknown package $package.");
-      _graphResults[package] = null;
-      graph.updateSources(ids);
+      var cascade = _cascades[package];
+      if (cascade == null) throw new ArgumentError("Unknown package $package.");
+      _cascadeResults[package] = null;
+      cascade.updateSources(ids);
     });
   }
 
   /// Removes [removed] from the graph's known set of source assets.
   void removeSources(Iterable<AssetId> sources) {
     groupBy(sources, (id) => id.package).forEach((package, ids) {
-      var graph = _graphs[package];
-      if (graph == null) throw new ArgumentError("Unknown package $package.");
-      _graphResults[package] = null;
-      graph.removeSources(ids);
+      var cascade = _cascades[package];
+      if (cascade == null) throw new ArgumentError("Unknown package $package.");
+      _cascadeResults[package] = null;
+      cascade.removeSources(ids);
     });
   }
 }