Add more metadata to non-programmatic barback exceptions.

pkg/barback/lib/src/asset_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.asset_node;
 
 import 'dart:async';
 
 import 'asset.dart';
 import 'asset_id.dart';
 import 'errors.dart';
 import 'phase.dart';
 import 'transform_node.dart';
 
 /// Describes the current state of an asset as part of a transformation graph.
 ///
 /// An asset node can be in one of three states (see [AssetState]). It provides
 /// an [onStateChange] stream that emits an event whenever it changes state.
 ///
 /// Asset nodes are controlled using [AssetNodeController]s.
 class AssetNode {
   /// The id of the asset that this node represents.
   final AssetId id;
 
+  /// The transform that created this asset node.
+  ///
+  /// This is `null` for source assets.
+  final TransformNode transform;
+
   /// The current state of the asset node.
   AssetState get state => _state;
   AssetState _state;
 
   /// The concrete asset that this node represents.
   ///
   /// This is null unless [state] is [AssetState.AVAILABLE].
   Asset get asset => _asset;
   Asset _asset;
 
@@ skipping 64 matching lines @@
 
   /// Returns a Future that completes as soon as the node is in a state that
   /// matches [test].
   ///
   /// The Future completes synchronously if this is already in such a state.
   Future<AssetState> _waitForState(bool test(AssetState state)) {
     if (test(state)) return new Future.sync(() => state);
     return onStateChange.firstWhere(test);
   }
 
-  AssetNode._(this.id)
+  AssetNode._(this.id, this.transform)
       : _state = AssetState.DIRTY;
 
-  AssetNode._available(Asset asset)
+  AssetNode._available(Asset asset, this.transform)
       : id = asset.id,
         _asset = asset,
         _state = AssetState.AVAILABLE;
 }
 
 /// The controller for an [AssetNode].
 ///
 /// This controls which state the node is in.
 class AssetNodeController {
   final AssetNode node;
 
   /// Creates a controller for a dirty node.
-  AssetNodeController(AssetId id)
-      : node = new AssetNode._(id);
+  AssetNodeController(AssetId id, [TransformNode transform])
+      : node = new AssetNode._(id, transform);
 
   /// Creates a controller for an available node with the given concrete
   /// [asset].
-  AssetNodeController.available(Asset asset)
-      : node = new AssetNode._available(asset);
+  AssetNodeController.available(Asset asset, [TransformNode transform])
+      : node = new AssetNode._available(asset, transform);
 
   /// Marks the node as [AssetState.DIRTY].
   void setDirty() {
     assert(node._state != AssetState.REMOVED);
     node._state = AssetState.DIRTY;
     node._asset = null;
     node._stateChangeController.add(AssetState.DIRTY);
   }
 
   /// Marks the node as [AssetState.REMOVED].
@@ skipping 45 matching lines @@
 
   /// Whether this state is [AssetState.DIRTY].
   bool get isDirty => this == AssetState.DIRTY;
 
   final String name;
 
   const AssetState._(this.name);
 
   String toString() => name;
 }