Share code between the transformer isolate and pub proper.

sdk/lib/_internal/pub/asset/dart/serialize/transform.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.transform;
+
+import 'dart:async';
+import 'dart:isolate';
+import 'dart:convert';
+
+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 '../utils.dart';
+
+/// Converts [transform] into a serializable map.
+Map serializeTransform(Transform transform) {
+  var receivePort = new ReceivePort();
+  receivePort.listen((wrappedMessage) {
+    respond(wrappedMessage, (message) {
+      if (message['type'] == 'getInput') {
+        return transform.getInput(deserializeId(message['id']))
+            .then((asset) => serializeAsset(asset));
+      }
+
+      if (message['type'] == 'addOutput') {
+        transform.addOutput(deserializeAsset(message['output']));
+        return null;
+      }
+
+      if (message['type'] == 'consumePrimary') {
+        transform.consumePrimary();
+        return null;
+      }
+
+      assert(message['type'] == 'log');
+      var method;
+      if (message['level'] == 'Info') {
+        method = transform.logger.info;
+      } else if (message['level'] == 'Fine') {
+        method = transform.logger.fine;
+      } else if (message['level'] == 'Warning') {
+        method = transform.logger.warning;
+      } else {
+        assert(message['level'] == 'Error');
+        method = transform.logger.error;
+      }
+
+      var assetId = message['assetId'] == null ? null :
+        deserializeId(message['assetId']);
+      var span = message['span'] == null ? null :
+        deserializeSpan(message['span']);
+      method(message['message'], asset: assetId, span: span);
+    });
+  });
+
+  return {
+    'port': receivePort.sendPort,
+    'primaryInput': serializeAsset(transform.primaryInput)
+  };
+}
+
+/// A wrapper for a [Transform] that's in the host isolate.
+///
+/// This retrieves inputs from and sends outputs and logs to the host isolate.
+class ForeignTransform implements Transform {
+  /// The port with which we communicate with the host isolate.
+  ///
+  /// This port and all messages sent across it are specific to this transform.
+  final SendPort _port;
+
+  final Asset primaryInput;
+
+  TransformLogger get logger => _logger;
+  TransformLogger _logger;
+
+  /// Creates a transform from a serializable map sent from the host isolate.
+  ForeignTransform(Map transform)
+      : _port = transform['port'],
+        primaryInput = deserializeAsset(transform['primaryInput']) {
+    _logger = new TransformLogger((assetId, level, message, span) {
+      call(_port, {
+        'type': 'log',
+        'level': level.name,
+        'message': message,
+        'assetId': assetId == null ? null : serializeId(assetId),
+        'span': span == null ? null : serializeSpan(span)
+      });
+    });
+  }
+
+  Future<Asset> getInput(AssetId id) {
+    return call(_port, {
+      'type': 'getInput',
+      'id': serializeId(id)
+    }).then(deserializeAsset);
+  }
+
+  Future<String> readInputAsString(AssetId id, {Encoding encoding}) {
+    if (encoding == null) encoding = UTF8;
+    return getInput(id).then((input) => input.readAsString(encoding: encoding));
+  }
+
+  Stream<List<int>> readInput(AssetId id) =>
+      futureStream(getInput(id).then((input) => input.read()));
+
+  Future<bool> hasInput(AssetId id) {
+    return getInput(id).then((_) => true).catchError((error) {
+      if (error is AssetNotFoundException && error.id == id) return false;
+      throw error;
+    });
+  }
+
+  void addOutput(Asset output) {
+    call(_port, {
+      'type': 'addOutput',
+      'output': serializeAsset(output)
+    });
+  }
+
+  void consumePrimary() {
+    call(_port, {'type': 'consumePrimary'});
+  }
+}