Load the transformer isolate code from pub's asset directory.

sdk/lib/_internal/pub/asset/dart/transformer_isolate.dart

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// 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.load_transformers;
+// Explicitly avoid using a library tag because pub will add additional imports

[Bob Nystrom, 2014/03/17 21:16:07]

Wording this as an imperative sentence seems a bit strange. How about:

// Note: This explicitly avoids...

[nweiz, 2014/03/17 22:20:40]

Done.

+// at the top of the file.
 
 import 'dart:async';
-import 'dart:convert';
-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 'package:source_maps/source_maps.dart';
-import 'package:stack_trace/stack_trace.dart';
-
-import '../barback.dart';
-import '../dart.dart' as dart;
-import '../log.dart' as log;
-import '../utils.dart';
-import 'build_environment.dart';
-import 'excluding_transformer.dart';
-import 'server.dart';
-
-/// A Dart script to run in an isolate.
-///
-/// This script serializes one or more transformers defined in a Dart library
-/// and marshals calls to and from them with the host isolate.
-const _TRANSFORMER_ISOLATE = """
-import 'dart:async';
 import 'dart:isolate';
 import 'dart:convert';
 import 'dart:mirrors';
 
 import '<<URL_BASE>>/packages/source_maps/span.dart';
 import '<<URL_BASE>>/packages/stack_trace/stack_trace.dart';
 import '<<URL_BASE>>/packages/barback/barback.dart';
 // TODO(nweiz): don't import from "src" once issue 14966 is fixed.
 import '<<URL_BASE>>/packages/barback/src/internal_asset.dart';

[Bob Nystrom, 2014/03/17 21:16:07]

How does the analyzer handle these?

[nweiz, 2014/03/17 22:20:40]

Poorly. That's why this CL adds a skip to the analyzer status file. Followup CLs
will make this work.

 
 /// Sets up the initial communication with the host isolate.
 void main(_, SendPort replyTo) {
   var port = new ReceivePort();
   replyTo.send(port.sendPort);
   port.first.then((wrappedMessage) {
     _respond(wrappedMessage, (message) {
       var library = Uri.parse(message['library']);
       var configuration = JSON.decode(message['configuration']);
       var mode = new BarbackMode(message['mode']);
@@ skipping 87 matching lines @@
       'output': serializeAsset(output)
     });
   }
 }
 
 /// Returns the mirror for the root Object type.
 ClassMirror get objectMirror => reflectClass(Object);
 
 // TODO(nweiz): clean this up when issue 13248 is fixed.
 MethodMirror getConstructor(ClassMirror classMirror, String constructor) {
-  var name = new Symbol("\${MirrorSystem.getName(classMirror.simpleName)}"
-      ".\$constructor");
+  var name = new Symbol("${MirrorSystem.getName(classMirror.simpleName)}"
+      ".$constructor");
   var candidate = classMirror.declarations[name];
   if (candidate is MethodMirror && candidate.isConstructor) return candidate;
   return null;
 }
 
 // TODO(nweiz): get rid of this when issue 12439 is fixed.
 /// Returns whether or not [mirror] is a subtype of [superclass].
 ///
 /// This includes [superclass] being mixed in to or implemented by [mirror].
 bool classIsA(ClassMirror mirror, ClassMirror superclass) {
@@ skipping 148 matching lines @@
   /// boundaries.
   static Map serialize(error, [StackTrace stack]) {
     if (stack == null && error is Error) stack = error.stackTrace;
     return {
       'type': error.runtimeType.toString(),
       'message': getErrorMessage(error),
       'stack': stack == null ? null : new Chain.forTrace(stack).toString()
     };
   }
 
-  String toString() => "\$message\\n\$stackTrace";
+  String toString() => "$message\n$stackTrace";
 }
 
 /// An [AssetNotFoundException] that was originally raised in another isolate. 
 class _CrossIsolateAssetNotFoundException extends CrossIsolateException
     implements AssetNotFoundException {
-  final TransformInfo transform;
   final AssetId id;
 
-  String get message => "Could not find asset \$id.";
+  String get message => "Could not find asset $id.";
 
   /// Loads a [_CrossIsolateAssetNotFoundException] from a serialized
   /// representation.
   ///
   /// [error] should be the result of
   /// [_CrossIsolateAssetNotFoundException.serialize].
   _CrossIsolateAssetNotFoundException.deserialize(Map error)
       : id = new AssetId(error['package'], error['path']),
         super.deserialize(error);
 
@@ skipping 67 matching lines @@
     subscription = callback().listen(controller.add,
         onError: controller.addError,
         onDone: controller.close);
   },
       onCancel: () => subscription.cancel(),
       onPause: () => subscription.pause(),
       onResume: () => subscription.resume(),
       sync: true);
   return controller.stream;
 }
-""";
-
-/// Load and return all transformers and groups from the library identified by
-/// [id].
-Future<Set> loadTransformers(BuildEnvironment environment,
-    BarbackServer transformerServer, TransformerId id) {
-  return id.getAssetId(environment.barback).then((assetId) {
-    var path = assetId.path.replaceFirst('lib/', '');
-    // TODO(nweiz): load from a "package:" URI when issue 12474 is fixed.
-
-    var baseUrl = transformerServer.url;
-    var uri = '$baseUrl/packages/${id.package}/$path';
-    var code = 'import "$uri";\n' +
-        _TRANSFORMER_ISOLATE.replaceAll('<<URL_BASE>>', baseUrl);
-    log.fine("Loading transformers from $assetId");
-
-    var port = new ReceivePort();
-    return dart.runInIsolate(code, port.sendPort)
-        .then((_) => port.first)
-        .then((sendPort) {
-      return _call(sendPort, {
-        'library': uri,
-        'mode': environment.mode.name,
-        // TODO(nweiz): support non-JSON-encodable configuration maps.
-        'configuration': JSON.encode(id.configuration)
-      }).then((transformers) {
-        transformers = transformers.map(
-            (transformer) => _deserializeTransformerOrGroup(transformer, id))
-            .toSet();
-        log.fine("Transformers from $assetId: $transformers");
-        return transformers;
-      });
-    }).catchError((error, stackTrace) {
-      if (error is! dart.CrossIsolateException) throw error;
-      if (error.type != 'IsolateSpawnException') throw error;
-      // TODO(nweiz): don't parse this as a string once issues 12617 and 12689
-      // are fixed.
-      if (!error.message.split('\n')[1].startsWith('import "$uri";')) {
-        throw error;
-      }
-
-      // If there was an IsolateSpawnException and the import that actually
-      // failed was the one we were loading transformers from, throw an
-      // application exception with a more user-friendly message.
-      fail('Transformer library "package:${id.package}/$path" not found.',
-          error, stackTrace);
-    });
-  });
-}
-
-/// A wrapper for a transformer that's in a different isolate.
-class _ForeignTransformer extends Transformer {
-  /// The port with which we communicate with the child isolate.
-  ///
-  /// This port and all messages sent across it are specific to this
-  /// transformer.
-  final SendPort _port;
-
-  /// The result of calling [toString] on the transformer in the isolate.
-  final String _toString;
-
-  _ForeignTransformer(Map map)
-      : _port = map['port'],
-        _toString = map['toString'];
-
-  Future<bool> isPrimary(Asset asset) {
-    return _call(_port, {
-      'type': 'isPrimary',
-      'asset': serializeAsset(asset)
-    });
-  }
-
-  Future apply(Transform transform) {
-    return _call(_port, {
-      'type': 'apply',
-      'transform': _serializeTransform(transform)
-    });
-  }
-
-  String toString() => _toString;
-}
-
-/// A wrapper for a transformer group that's in a different isolate.
-class _ForeignGroup implements TransformerGroup {
-  final Iterable<Iterable> phases;
-
-  /// The result of calling [toString] on the transformer group in the isolate.
-  final String _toString;
-
-  _ForeignGroup(TransformerId id, Map map)
-      : phases = map['phases'].map((phase) {
-          return phase.map((transformer) => _deserializeTransformerOrGroup(
-              transformer, id)).toList();
-        }).toList(),
-        _toString = map['toString'];
-
-  String toString() => _toString;
-}
-
-/// Converts a serializable map into a [Transformer] or a [TransformerGroup].
-_deserializeTransformerOrGroup(Map map, TransformerId id) {
-  if (map['type'] == 'Transformer') {
-    var transformer = new _ForeignTransformer(map);
-    return ExcludingTransformer.wrap(transformer, id.includes, id.excludes);
-  }
-
-  assert(map['type'] == 'TransformerGroup');
-  return new _ForeignGroup(id, map);
-}
-
-/// 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;
-      }
-
-      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)
-  };
-}
-
-/// Converts a serializable map into an [AssetId].
-AssetId _deserializeId(Map id) => new AssetId(id['package'], id['path']);
-
-/// Converts a serializable map into a [Span].
-Span _deserializeSpan(Map span) {
-  assert(span['type'] == 'fixed');
-  var location = _deserializeLocation(span['start']);
-  return new FixedSpan(span['sourceUrl'], location.offset, location.line,
-      location.column, text: span['text'], isIdentifier: span['isIdentifier']);
-}
-
-/// Converts a serializable map into a [Location].
-Location _deserializeLocation(Map location) {
-  assert(location['type'] == 'fixed');
-  return new FixedLocation(location['offset'], location['sourceUrl'],
-      location['line'], location['column']);
-}
-
-/// Converts [id] into a serializable map.
-Map _serializeId(AssetId id) => {'package': id.package, 'path': id.path};
-
-/// Responds to a message sent by [_call].
-///
-/// [wrappedMessage] is the raw message sent by [_call]. This unwraps it and
-/// passes the contents of the message to [callback], then sends the return
-/// value of [callback] back to [_call]. If [callback] returns a Future or
-/// throws an error, that will also be sent.
-void _respond(wrappedMessage, callback(message)) {
-  var replyTo = wrappedMessage['replyTo'];
-  syncFuture(() => callback(wrappedMessage['message']))
-      .then((result) => replyTo.send({'type': 'success', 'value': result}))
-      .catchError((error, stackTrace) {
-    replyTo.send({
-      'type': 'error',
-      'error': _serializeException(error, stackTrace)
-    });
-  });
-}
-
-/// Wraps [message] and sends it across [port], then waits for a response which
-/// should be sent using [_respond].
-///
-/// The returned Future will complete to the value or error returned by
-/// [_respond].
-Future _call(SendPort port, message) {
-  var receivePort = new ReceivePort();
-  port.send({
-    'message': message,
-    'replyTo': receivePort.sendPort
-  });
-
-  return Chain.track(receivePort.first).then((response) {
-    if (response['type'] == 'success') return response['value'];
-    assert(response['type'] == 'error');
-    var exception = _deserializeException(response['error']);
-    return new Future.error(exception, exception.stackTrace);
-  });
-}
-
-/// An [AssetNotFoundException] that was originally raised in another isolate. 
-class _CrossIsolateAssetNotFoundException extends dart.CrossIsolateException
-    implements AssetNotFoundException {
-  final AssetId id;
-
-  String get message => "Could not find asset $id.";
-
-  /// Loads a [_CrossIsolateAssetNotFoundException] from a serialized
-  /// representation.
-  ///
-  /// [error] should be the result of
-  /// [_CrossIsolateAssetNotFoundException.serialize].
-  _CrossIsolateAssetNotFoundException.deserialize(Map error)
-      : id = new AssetId(error['package'], error['path']),
-        super.deserialize(error);
-
-  /// Serializes [error] to an object that can safely be passed across isolate
-  /// boundaries.
-  static Map serialize(AssetNotFoundException error, [StackTrace stack]) {
-    var map = dart.CrossIsolateException.serialize(error);
-    map['package'] = error.id.package;
-    map['path'] = error.id.path;
-    return map;
-  }
-}
-
-/// Serializes [error] to an object that can safely be passed across isolate
-/// boundaries.
-///
-/// This handles [AssetNotFoundException]s specially, ensuring that their
-/// metadata is preserved.
-Map _serializeException(error, [StackTrace stack]) {
-  if (error is AssetNotFoundException) {
-    return _CrossIsolateAssetNotFoundException.serialize(error, stack);
-  } else {
-    return dart.CrossIsolateException.serialize(error, stack);
-  }
-}
-
-/// Loads an exception from a serialized representation.
-///
-/// This handles [AssetNotFoundException]s specially, ensuring that their
-/// metadata is preserved.
-dart.CrossIsolateException _deserializeException(Map error) {
-  if (error['type'] == 'AssetNotFoundException') {
-    return new _CrossIsolateAssetNotFoundException.deserialize(error);
-  } else {
-    return new dart.CrossIsolateException.deserialize(error);
-  }
-}