Add observatory_pub_packages snapshot to third_party

observatory_pub_packages/barback/src/graph/group_runner.dart

Index: observatory_pub_packages/barback/src/graph/group_runner.dart
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--- observatory_pub_packages/barback/src/graph/group_runner.dart	(revision 0)
+++ observatory_pub_packages/barback/src/graph/group_runner.dart	(working copy)
@@ -0,0 +1,89 @@
+// 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.group_runner;
+
+import 'dart:async';
+
+import '../asset/asset_node.dart';
+import '../log.dart';
+import '../transformer/transformer_group.dart';
+import '../utils/stream_pool.dart';
+import 'node_status.dart';
+import 'phase.dart';
+
+/// A class that processes all of the phases in a single transformer group.
+///
+/// A group takes many inputs, processes them, and emits many outputs.
+class GroupRunner {
+  /// The group this runner runs.
+  final TransformerGroup _group;
+
+  /// A string describing the location of [this] in the transformer graph.
+  final String _location;
+
+  /// The phases defined by this group.
+  final _phases = new List<Phase>();
+
+  /// How far along [this] is in processing its assets.
+  NodeStatus get status {
+    // Just check the last phase, since it will check all the previous phases
+    // itself.
+    return _phases.last.status;
+  }
+
+  /// A stream that emits an event every time the group's status changes.
+  Stream<NodeStatus> get onStatusChange => _onStatusChange;
+  Stream _onStatusChange;
+
+  /// A stream that emits any new assets emitted by [this].
+  ///
+  /// Assets are emitted synchronously to ensure that any changes are thoroughly
+  /// propagated as soon as they occur.
+  Stream<AssetNode> get onAsset => _onAsset;
+  Stream<AssetNode> _onAsset;
+
+  /// A stream that emits an event whenever any transforms in this group logs
+  /// an entry.
+  Stream<LogEntry> get onLog => _onLogPool.stream;
+  final _onLogPool = new StreamPool<LogEntry>.broadcast();
+
+  GroupRunner(Phase previous, this._group, this._location) {
+    _addPhase(previous.addPhase(_location), []);
+    for (var phase in _group.phases) {
+      _addPhase(_phases.last.addPhase(), phase);
+    }
+
+    _onAsset = _phases.last.onAsset;
+    _onStatusChange = _phases.last.onStatusChange;
+  }
+
+  /// Add a phase with [contents] to [this]'s list of phases.
+  ///
+  /// [contents] should be an inner [Iterable] from a [TransformGroup.phases]
+  /// value.
+  void _addPhase(Phase phase, Iterable contents) {
+    _phases.add(phase);
+    _onLogPool.add(phase.onLog);
+    phase.updateTransformers(contents);
+  }
+
+  /// Force all [LazyTransformer]s' transforms in this group to begin producing
+  /// concrete assets.
+  void forceAllTransforms() {
+    for (var phase in _phases) {
+      phase.forceAllTransforms();
+    }
+  }
+
+  /// Removes this group and all sub-phases within it.
+  void remove() {
+    _onLogPool.close();
+    for (var phase in _phases) {
+      phase.remove();
+    }
+  }
+
+  String toString() => "group in phase $_location for $_group";
+}