Big merge from experimental to bleeding edge.

sdk/lib/core/sink.dart

+// Copyright (c) 2012, 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.
+
+/**
+ * An interface for an object that can receive a sequence of values.
+ */
+abstract class Sink<T> {
+  /** Write a value to the sink. */
+  add(T value);
+  /** Tell the sink that no further values will be written. */
+  void close();
+}
+
+// ----------------------------------------------------------------------
+// Collections/Sink interoperability
+// ----------------------------------------------------------------------
+
+typedef void _CollectionSinkCallback<T>(Collection<T> collection);
+
+/** Sink that stores incoming data in a collection. */
+class CollectionSink<T> implements Sink<T> {
+  final Collection<T> collection;
+  final _CollectionSinkCallback<T> callback;
+  bool _isClosed = false;
+
+  CollectionSink(this.collection, [void callback(Collection<T> collection)])
+      : this.callback = callback;
+
+  add(T value) {
+    if (_isClosed) throw new StateError("Adding to closed sink");
+    collection.add(value);
+  }
+
+  void close() {
+    if (_isClosed) throw new StateError("Closing closed sink");
+    _isClosed = true;
+    if (callback != null) callback(collection);
+  }
+}