Add more metadata to non-programmatic barback exceptions.

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';
@@ skipping 46 matching lines @@
   TransformNode(this.phase, this.transformer, this.primary) {
     _primarySubscription = primary.onStateChange.listen((state) {
       if (state.isRemoved) {
         remove();
       } else {
         _dirty();
       }
     });
   }
 
+  /// The [TransformInfo] describing this node.
+  ///
+  /// [TransformInfo] is the publicly-visible representation of a transform
+  /// node.
+  TransformInfo get info => new TransformInfo(transformer, primary.id);
+
   /// Marks this transform as removed.
   ///
   /// This causes all of the transform's outputs to be marked as removed as
   /// well. Normally this will be automatically done internally based on events
   /// from the primary input, but it's possible for a transform to no longer be
   /// valid even if its primary input still exists.
   void remove() {
     _isDirty = true;
     _onDirtyController.close();
     _primarySubscription.cancel();
@@ skipping 32 matching lines @@
       subscription.cancel();
     }
     _inputSubscriptions.clear();
 
     _isDirty = false;
     return transformer.apply(transform).catchError((error) {
       // If the transform became dirty while processing, ignore any errors from
       // it.
       if (_isDirty) return;
 
+      if (error is! MissingInputException) {
+        error = new TransformerException(info, error);
+      }
+
       // Catch all transformer errors and pipe them to the results stream.
       // This is so a broken transformer doesn't take down the whole graph.
       phase.cascade.reportError(error);
 
       // Don't allow partial results from a failed transform.
       newOutputs.clear();
     }).then((_) {
       if (_isDirty) return [];
 
       return _adjustOutputs(newOutputs);
     });
   }
 
   /// Gets the asset for an input [id].
   ///
   /// If an input with that ID cannot be found, throws an
   /// [AssetNotFoundException].
   Future<Asset> getInput(AssetId id) {
     return phase.getInput(id).then((node) {
       // Throw if the input isn't found. This ensures the transformer's apply
       // is exited. We'll then catch this and report it through the proper
       // results stream.
-      if (node == null) throw new MissingInputException(id);
+      if (node == null) throw new MissingInputException(info, id);
 
       // If the asset node is found, wait until its contents are actually
       // available before we return them.
       return node.whenAvailable.then((asset) {
         _inputSubscriptions.putIfAbsent(node.id,
             () => node.onStateChange.listen((_) => _dirty()));
 
         return asset;
       }).catchError((error) {
         if (error is! AssetNotFoundException || error.id != id) throw error;
         // If the node was removed before it could be loaded, treat it as though
         // it never existed and throw a MissingInputException.
-        throw new MissingInputException(id);
+        throw new MissingInputException(info, id);
       });
     });
   }
 
   /// Adjusts the outputs of the transform to reflect the outputs emitted on its
   /// most recent run.
   Set<AssetNode> _adjustOutputs(AssetSet newOutputs) {
     // Any ids that are for a different package are invalid.
     var invalidIds = newOutputs
         .map((asset) => asset.id)
         .where((id) => id.package != phase.cascade.package)
         .toSet();
     for (var id in invalidIds) {
       newOutputs.removeId(id);
       // TODO(nweiz): report this as a warning rather than a failing error.
-      phase.cascade.reportError(
-          new InvalidOutputException(phase.cascade.package, id));
+      phase.cascade.reportError(new InvalidOutputException(info, id));
     }
 
     // Remove outputs that used to exist but don't anymore.
     for (var id in _outputControllers.keys.toList()) {
       if (newOutputs.containsId(id)) continue;
       _outputControllers.remove(id).setRemoved();
     }
 
     var brandNewOutputs = new Set<AssetNode>();
     // Store any new outputs or new contents for existing outputs.
     for (var asset in newOutputs) {
       var controller = _outputControllers[asset.id];
       if (controller != null) {
         controller.setAvailable(asset);
       } else {
         var controller = new AssetNodeController.available(asset);
         _outputControllers[asset.id] = controller;
         brandNewOutputs.add(controller.node);
       }
     }
 
     return brandNewOutputs;
   }
 }