Improve barback/pub logging.

pkg/barback/lib/src/transform_node.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.transform_node;
 
 import 'dart:async';
 
 import 'asset.dart';
 import 'asset_id.dart';
 import 'asset_node.dart';
 import 'asset_set.dart';
+import 'barback_logger.dart';
 import 'errors.dart';
 import 'phase.dart';
 import 'transform.dart';
 import 'transformer.dart';
 
 /// Describes a transform on a set of assets and its relationship to the build
 /// dependency graph.
 ///
 /// Keeps track of whether it's dirty and needs to be run and which assets it
 /// depends on.
@@ skipping 23 matching lines @@
 
   /// A stream that emits an event whenever this transform becomes dirty and
   /// needs to be re-run.
   ///
   /// This may emit events when the transform was already dirty or while
   /// processing transforms. Events are emitted synchronously to ensure that the
   /// dirty state is thoroughly propagated as soon as any assets are changed.
   Stream get onDirty => _onDirtyController.stream;
   final _onDirtyController = new StreamController.broadcast(sync: true);
 
+  /// A stream that emits an event whenever this transform logs an entry.
+  Stream<LogEntry> get onLog => _onLogController.stream;
+  final _onLogController = new StreamController<LogEntry>.broadcast();
+
   TransformNode(this.phase, this.transformer, this.primary) {
     _primarySubscription = primary.onStateChange.listen((state) {
       if (state.isRemoved) {
         remove();
       } else {
         _dirty();
       }
     });
   }
 
@@ skipping 33 matching lines @@
   }
 
   /// Applies this transform.
   ///
   /// Returns a set of asset nodes representing the outputs from this transform
   /// that weren't emitted last time it was run.
   Future<Set<AssetNode>> apply() {
     assert(!_onDirtyController.isClosed);
 
     var newOutputs = new AssetSet();
-    var transform = createTransform(this, newOutputs);
+    var transform = createTransform(this, newOutputs, _log);
 
     // Clear all the old input subscriptions. If an input is re-used, we'll
     // re-subscribe.
     for (var subscription in _inputSubscriptions.values) {
       subscription.cancel();
     }
     _inputSubscriptions.clear();
 
     _isDirty = false;
     return transformer.apply(transform).catchError((error) {
@@ skipping 73 matching lines @@
         controller.setAvailable(asset);
       } else {
         var controller = new AssetNodeController.available(asset, this);
         _outputControllers[asset.id] = controller;
         brandNewOutputs.add(controller.node);
       }
     }
 
     return brandNewOutputs;
   }
+
+  void _log(AssetId asset, LogLevel level, String message, Span span) {
+    // If the log isn't already associated with an asset, use the primary.
+    if (asset == null) asset = primary.id;
+    var info = new TransformInfo(transformer, primary.id);

[nweiz, 2013/10/16 19:41:27]

There's already an info getter that does this.

[Bob Nystrom, 2013/10/28 23:45:56]

Done.

+    var entry = new LogEntry(info, asset, level, message, span);
+    _onLogController.add(entry);
+  }
 }