Make barback more package-aware.

pkg/barback/lib/src/asset_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;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'asset.dart';
 import 'asset_id.dart';
+import 'asset_graph_manager.dart';
 import 'asset_provider.dart';
 import 'asset_set.dart';
 import 'errors.dart';
 import 'change_batch.dart';
 import 'phase.dart';
 import 'transformer.dart';
+import 'utils.dart';
 
-/// The main build dependency manager.
+/// The asset manager for an individual package.
 ///
-/// For any given input file, it can tell which output files are affected by
-/// it, and vice versa.
+/// This keeps track of which transformers are applied to which assets, and
+/// re-runs those transformers when their dependencies change. The transformed
+/// assets are accessible via [getAssetById].
 class AssetGraph {
-  final AssetProvider _provider;
+  /// The name of the package whose assets are managed.
+  final String package;
+
+  /// The [AssetGraphManager] that manages the [AssetGraph]s for all
+  /// dependencies of the current app.
+  final AssetGraphManager _manager;
 
   final _phases = <Phase>[];
 
   /// A stream that emits a [BuildResult] each time the build is completed,
   /// whether or not it succeeded.
   ///
   /// 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();
@@ skipping 15 matching lines @@
 
   /// A future that completes when the currently running build process finishes.
   ///
   /// If no build it in progress, is `null`.
   Future _processDone;
 
   ChangeBatch _sourceChanges;
 
   /// Creates a new [AssetGraph].
   ///
-  /// It loads source assets using [provider] and then uses [transformerPhases]
-  /// to generate output files from them.
+  /// It loads source assets within [package] using [provider] and then uses
+  /// [transformerPhases] to generate output files from them.
   //TODO(rnystrom): Better way of specifying transformers and their ordering.
-  AssetGraph(this._provider,
+  AssetGraph(this._manager, this.package,
       Iterable<Iterable<Transformer>> transformerPhases) {
     // Flatten the phases to a list so we can traverse backwards to wire up
     // each phase to its next.
     var phases = transformerPhases.toList();
 
     // Each phase writes its outputs as inputs to the next phase after it.
     // Add a phase at the end for the final outputs of the last phase.
     phases.add([]);
 
     Phase nextPhase = null;
     for (var transformers in phases.reversed) {
       nextPhase = new Phase(this, _phases.length, transformers.toList(),
           nextPhase);
       _phases.insert(0, nextPhase);
     }
   }
 
   /// 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) {
+    assert(id.package == package);
+
     // TODO(rnystrom): Waiting for the entire build to complete is unnecessary
     // in some cases. Should optimize:
     // * [id] may be generated before the compilation is finished. We should
     //   be able to quickly check whether there are any more in-place
     //   transformations that can be run on it. If not, we can return it early.
     // * If everything is compiled, something that didn't output [id] is
     //   dirtied, and then [id] is requested, we can return it immediately,
     //   since anything overwriting it at that point is an error.
     // * If [id] has never been generated and all active transformers provide
     //   metadata about the file names of assets it can emit, we can prove that
     //   none of them can emit [id] and fail early.
-    return _waitForProcess().then((_) {
+    return (_processDone == null ? new Future.value() : _processDone).then((_) {
       // Each phase's inputs are the outputs of the previous phase. Find the
       // last phase that contains the asset. Since the last phase has no
       // transformers, this will find the latest output for that id.
 
       // TODO(rnystrom): Currently does not omit assets that are actually used
       // as inputs for transformers. This means you can request and get an
       // asset that should be "consumed" because it's used to generate the
       // real asset you care about. Need to figure out how we want to handle
       // that and what use cases there are related to it.
       for (var i = _phases.length - 1; i >= 0; i--) {
@@ skipping 10 matching lines @@
     });
   }
 
   /// 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) {
     if (_sourceChanges == null) _sourceChanges = new ChangeBatch();
+    assert(sources.every((id) => id.package == package));

[Bob Nystrom, 2013/07/11 23:03:40]

Alternatively, it could just ignore sources outside of its package. That might
be easier on the caller.

[nweiz, 2013/07/15 22:11:44]

Since this should only be called by [AssetGraphManager], I think it makes sense
to be strict about what gets passed in. If we're getting an id from a different
package, something's probably seriously wrong.

     _sourceChanges.update(sources);
 
     _waitForProcess();
   }
 
   /// Removes [removed] from the graph's known set of source assets.
   void removeSources(Iterable<AssetId> removed) {
     if (_sourceChanges == null) _sourceChanges = new ChangeBatch();
+    assert(removed.every((id) => id.package == package));
     _sourceChanges.remove(removed);
 
     _waitForProcess();
   }
 
   void reportError(error) {
     _accumulatedErrors.add(error);
     _errorsController.add(error);
   }
 
@@ skipping 64 matching lines @@
 
       // Take the current batch to ensure it doesn't get added to while we're
       // processing it.
       var changes = _sourceChanges;
       _sourceChanges = null;
 
       var updated = new AssetSet();
       var futures = [];
       for (var id in changes.updated) {
         // TODO(rnystrom): Catch all errors from provider and route to results.
-        futures.add(_provider.getAsset(id).then((asset) {
+        futures.add(_manager.provider.getAsset(id).then((asset) {
           updated.add(asset);
         }).catchError((error) {
           if (error is AssetNotFoundException) {
             // Handle missing asset errors like regular missing assets.
             reportError(error);
           } else {
             // It's an unexpected error, so rethrow it.
             throw error;
           }
         }));
@@ skipping 13 matching lines @@
 /// although individual assets may still have built successfully.
 class BuildResult {
   /// All errors that occurred during the build.
   final List errors;
 
   /// `true` if the build succeeded.
   bool get succeeded => errors.isEmpty;
 
   BuildResult(Iterable errors)
       : errors = errors.toList();
+
+  /// Creates a build result indicating a successful build.
+  ///
+  /// This equivalent to a build result with no errors.
+  BuildResult.success()
+      : this([]);
+
+  String toString() {
+    if (succeeded) return "success";
+
+    return "errors:\n" + errors.map((error) {
+      var stackTrace = getAttachedStackTrace(error);
+      if (stackTrace != null) stackTrace = new Trace.from(stackTrace);
+
+      var msg = new StringBuffer();
+      msg.write(prefixLines(error.toString()));
+      if (stackTrace != null) {
+        msg.write("\n\n");
+        msg.write("Stack trace:\n");
+        msg.write(prefixLines(stackTrace.toString()));
+      }
+      return msg.toString();
+    }).join("\n\n");
+  }
 }