Share code between the transformer isolate and pub proper.

sdk/lib/_internal/pub/asset/dart/serialize/transformer.dart

+// Copyright (c) 2014, 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 pub.asset.serialize.transformer;
+
+import 'dart:isolate';
+
+import 'package:barback/barback.dart';
+// TODO(nweiz): don't import from "src" once issue 14966 is fixed.
+import 'package:barback/src/internal_asset.dart';
+
+import '../serialize.dart';
+import 'transform.dart';
+
+/// Converts [transformer] into a serializable map.
+Map serializeTransformer(Transformer transformer) {
+  var port = new ReceivePort();
+  port.listen((wrappedMessage) {
+    respond(wrappedMessage, (message) {
+      if (message['type'] == 'isPrimary') {
+        return transformer.isPrimary(deserializeAsset(message['asset']));
+      } else {
+        assert(message['type'] == 'apply');
+
+        // Make sure we return null so that if the transformer's [apply] returns
+        // a non-serializable value it doesn't cause problems.
+        return transformer.apply(
+            new ForeignTransform(message['transform'])).then((_) => null);
+      }
+    });
+  });
+
+  return {
+    'type': 'Transformer',
+    'toString': transformer.toString(),
+    'port': port.sendPort
+  };
+}
+
+// Converts [group] into a serializable map.
+Map serializeTransformerGroup(TransformerGroup group) {
+  return {
+    'type': 'TransformerGroup',
+    'toString': group.toString(),
+    'phases': group.phases.map((phase) {
+      return phase.map(serializeTransformerOrGroup).toList();
+    }).toList()
+  };
+}
+
+/// Converts [transformerOrGroup] into a serializable map.
+Map serializeTransformerOrGroup(transformerOrGroup) {
+  if (transformerOrGroup is Transformer) {
+    return serializeTransformer(transformerOrGroup);
+  } else {
+    assert(transformerOrGroup is TransformerGroup);
+    return serializeTransformerGroup(transformerOrGroup);
+  }
+}