Remove barback from the repo.

pkg/barback/lib/src/graph/phase_output.dart

Index: pkg/barback/lib/src/graph/phase_output.dart
diff --git a/pkg/barback/lib/src/graph/phase_output.dart b/pkg/barback/lib/src/graph/phase_output.dart
deleted file mode 100644
index 3d6460b657e3d9edcb90f4e82bdf8d22f6acb448..0000000000000000000000000000000000000000
--- a/pkg/barback/lib/src/graph/phase_output.dart
+++ /dev/null
@@ -1,114 +0,0 @@
-// 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.graph.phase_output;
-
-import 'dart:async';
-import 'dart:collection';
-
-import '../asset/asset_forwarder.dart';
-import '../asset/asset_node.dart';
-import '../errors.dart';
-import 'phase.dart';
-
-/// A class that handles a single output of a phase.
-///
-/// Normally there's only a single [AssetNode] for a phase's output, but it's
-/// possible that multiple transformers in the same phase emit assets with the
-/// same id, causing collisions. This handles those collisions by forwarding the
-/// chronologically first asset.
-///
-/// When the asset being forwarding changes, the old value of [output] will be
-/// marked as removed and a new value will replace it. Users of this class can
-/// be notified of this using [onAsset].
-class PhaseOutput {
-  /// The phase for which this is an output.
-  final Phase _phase;
-
-  /// A string describing the location of [this] in the transformer graph.
-  final String _location;
-
-  /// The asset node for this output.
-  AssetNode get output => _outputForwarder.node;
-  AssetForwarder _outputForwarder;
-
-  /// A stream that emits an [AssetNode] each time this output starts forwarding
-  /// a new asset.
-  Stream<AssetNode> get onAsset => _onAssetController.stream;
-  final _onAssetController =
-      new StreamController<AssetNode>.broadcast(sync: true);
-
-  /// The assets for this output.
-  ///
-  /// If there's no collision, this will only have one element. Otherwise, it
-  /// will be ordered by which asset was added first.
-  final _assets = new Queue<AssetNode>();
-
-  /// The [AssetCollisionException] for this output, or null if there is no
-  /// collision currently.
-  AssetCollisionException get collisionException {
-    if (_assets.length == 1) return null;
-    return new AssetCollisionException(
-        _assets.where((asset) => asset.transform != null)
-            .map((asset) => asset.transform.info),
-        output.id);
-  }
-
-  PhaseOutput(this._phase, AssetNode output, this._location)
-      : _outputForwarder = new AssetForwarder(output) {
-    assert(!output.state.isRemoved);
-    add(output);
-  }
-
-  /// Adds an asset node as an output with this id.
-  void add(AssetNode node) {
-    assert(node.id == output.id);
-    assert(!output.state.isRemoved);
-    _assets.add(node);
-    _watchAsset(node);
-  }
-
-  /// Removes all existing listeners on [output] without actually closing
-  /// [this].
-  ///
-  /// This marks [output] as removed, but immediately replaces it with a new
-  /// [AssetNode] in the same state as the old output. This is used when adding
-  /// a new [Phase] to cause consumers of the prior phase's outputs to be to
-  /// start consuming the new phase's outputs instead.
-  void removeListeners() {
-    _outputForwarder.close();
-    _outputForwarder = new AssetForwarder(_assets.first);
-    _onAssetController.add(output);
-  }
-
-  /// Watches [node] to adjust [_assets] and [output] when it's removed.
-  void _watchAsset(AssetNode node) {
-    node.whenRemoved(() {
-      if (_assets.length == 1) {
-        assert(_assets.single == node);
-        _outputForwarder.close();
-        _onAssetController.close();
-        return;
-      }
-
-      // If there was more than one asset, we're resolving a collision --
-      // possibly partially.
-      var wasFirst = _assets.first == node;
-      _assets.remove(node);
-
-      // If this was the first asset, we replace it with the next asset
-      // (chronologically).
-      if (wasFirst) removeListeners();
-
-      // If there's still a collision, report it. This lets the user know if
-      // they've successfully resolved the collision or not.
-      if (_assets.length > 1) {
-        // TODO(nweiz): report this through the output asset.
-        _phase.cascade.reportError(collisionException);
-      }
-    });
-  }
-
-  String toString() => "phase output in $_location for $output";
-}