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

sdk/lib/_internal/pub/lib/src/barback/load_transformers.dart

Index: sdk/lib/_internal/pub/lib/src/barback/load_transformers.dart
diff --git a/sdk/lib/_internal/pub/lib/src/barback/load_transformers.dart b/sdk/lib/_internal/pub/lib/src/barback/load_transformers.dart
index e385ef34a2c0b47ffbaec04fa4c09887f1d8d266..8987eac33eb034b1cc0ba9bda28912287582c134 100644
--- a/sdk/lib/_internal/pub/lib/src/barback/load_transformers.dart
+++ b/sdk/lib/_internal/pub/lib/src/barback/load_transformers.dart
@@ -11,408 +11,19 @@ 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:path/path.dart' as p;
 import 'package:source_maps/source_maps.dart';
 import 'package:stack_trace/stack_trace.dart';
 
 import '../barback.dart';
 import '../dart.dart' as dart;
+import '../io.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';
-
-/// 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']);
-      return initialize(library, configuration, mode).
-          map(_serializeTransformerOrGroup).toList();
-    });
-  });
-}
-
-/// Loads all the transformers and groups defined in [uri].
-///
-/// Loads the library, finds any Transformer or TransformerGroup subclasses in
-/// it, instantiates them with [configuration] and [mode], and returns them.
-Iterable initialize(Uri uri, Map configuration, BarbackMode mode) {
-  var mirrors = currentMirrorSystem();
-  var transformerClass = reflectClass(Transformer);
-  var groupClass = reflectClass(TransformerGroup);
-
-  // TODO(nweiz): if no valid transformers are found, throw an error message
-  // describing candidates and why they were rejected.
-  return mirrors.libraries[uri].declarations.values.map((declaration) {
-    if (declaration is! ClassMirror) return null;
-    var classMirror = declaration;
-    if (classMirror.isPrivate) return null;
-    if (classMirror.isAbstract) return null;
-    if (!classIsA(classMirror, transformerClass) &&
-        !classIsA(classMirror, groupClass)) {
-      return null;
-    }
-
-    var constructor = getConstructor(classMirror, 'asPlugin');
-    if (constructor == null) return null;
-    if (constructor.parameters.isEmpty) {
-      if (configuration.isNotEmpty) return null;
-      return classMirror.newInstance(const Symbol('asPlugin'), []).reflectee;
-    }
-    if (constructor.parameters.length != 1) return null;
-
-    return classMirror.newInstance(const Symbol('asPlugin'),
-        [new BarbackSettings(configuration, mode)]).reflectee;
-  }).where((classMirror) => classMirror != null);
-}
-
-/// 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()));
-
-  void addOutput(Asset output) {
-    _call(_port, {
-      'type': 'addOutput',
-      '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 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) {
-  if (mirror == superclass) return true;
-  if (mirror == objectMirror) return false;
-  return classIsA(mirror.superclass, superclass) ||
-      mirror.superinterfaces.any((int) => classIsA(int, superclass));
-}
-
-/// Converts [transformerOrGroup] into a serializable map.
-Map _serializeTransformerOrGroup(transformerOrGroup) {
-  if (transformerOrGroup is Transformer) {
-    return _serializeTransformer(transformerOrGroup);
-  } else {
-    assert(transformerOrGroup is TransformerGroup);
-    return _serializeTransformerGroup(transformerOrGroup);
-  }
-}
-
-/// 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 a serializable map into an [AssetId].
-AssetId _deserializeId(Map id) => new AssetId(id['package'], id['path']);
-
-/// Converts [id] into a serializable map.
-Map _serializeId(AssetId id) => {'package': id.package, 'path': id.path};
-
-/// Converts [span] into a serializable map.
-Map _serializeSpan(Span span) {
-  // TODO(nweiz): convert FileSpans to FileSpans.
-  return {
-    'type': 'fixed',
-    'sourceUrl': span.sourceUrl,
-    'start': _serializeLocation(span.start),
-    'text': span.text,
-    'isIdentifier': span.isIdentifier
-  };
-}
-
-/// Converts [location] into a serializable map.
-Map _serializeLocation(Location location) {
-  // TODO(nweiz): convert FileLocations to FileLocations.
-  return {
-    'type': 'fixed',
-    'sourceUrl': location.sourceUrl,
-    'offset': location.offset,
-    'line': location.line,
-    'column': location.column
-  };
-}
-
-/// 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'];
-  new Future.sync(() => 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 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 exception that was originally raised in another isolate.
-///
-/// Exception objects can't cross isolate boundaries in general, so this class
-/// wraps as much information as can be consistently serialized.
-class CrossIsolateException implements Exception {
-  /// The name of the type of exception thrown.
-  ///
-  /// This is the return value of [error.runtimeType.toString()]. Keep in mind
-  /// that objects in different libraries may have the same type name.
-  final String type;
-
-  /// The exception's message, or its [toString] if it didn't expose a `message`
-  /// property.
-  final String message;
-
-  /// The exception's stack chain, or `null` if no stack chain was available.
-  final Chain stackTrace;
-
-  /// Loads a [CrossIsolateException] from a serialized representation.
-  ///
-  /// [error] should be the result of [CrossIsolateException.serialize].
-  CrossIsolateException.deserialize(Map error)
-      : type = error['type'],
-        message = error['message'],
-        stackTrace = error['stack'] == null ? null :
-            new Chain.parse(error['stack']);
-
-  /// Serializes [error] to an object that can safely be passed across isolate
-  /// 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";
-}
-
-/// 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.";
-
-  /// 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 = 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 CrossIsolateException.serialize(error, stack);
-  }
-}
-
-/// Loads an exception from a serialized representation.
-///
-/// This handles [AssetNotFoundException]s specially, ensuring that their
-/// metadata is preserved.
-CrossIsolateException _deserializeException(Map error) {
-  if (error['type'] == 'AssetNotFoundException') {
-    return new _CrossIsolateAssetNotFoundException.deserialize(error);
-  } else {
-    return new CrossIsolateException.deserialize(error);
-  }
-}
-
-/// A regular expression to match the exception prefix that some exceptions'
-/// [Object.toString] values contain.
-final _exceptionPrefix = new RegExp(r'^([A-Z][a-zA-Z]*)?(Exception|Error): ');
-
-/// Get a string description of an exception.
-///
-/// Many exceptions include the exception class name at the beginning of their
-/// [toString], so we remove that if it exists.
-String getErrorMessage(error) =>
-  error.toString().replaceFirst(_exceptionPrefix, '');
-
-/// Returns a buffered stream that will emit the same values as the stream
-/// returned by [future] once [future] completes. If [future] completes to an
-/// error, the return value will emit that error and then close.
-Stream _futureStream(Future<Stream> future) {
-  var controller = new StreamController(sync: true);
-  future.then((stream) {
-    stream.listen(
-        controller.add,
-        onError: controller.addError,
-        onDone: controller.close);
-  }).catchError((e, stackTrace) {
-    controller.addError(e, stackTrace);
-    controller.close();
-  });
-  return controller.stream;
-}
-
-Stream callbackStream(Stream callback()) {
-  var subscription;
-  var controller;
-  controller = new StreamController(onListen: () {
-    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,
@@ -424,7 +35,8 @@ Future<Set> loadTransformers(BuildEnvironment environment,
     var baseUrl = transformerServer.url;
     var uri = '$baseUrl/packages/${id.package}/$path';
     var code = 'import "$uri";\n' +
-        _TRANSFORMER_ISOLATE.replaceAll('<<URL_BASE>>', baseUrl);
+        readResource(p.join("dart", "transformer_isolate.dart"))
+            .replaceAll('<<URL_BASE>>', baseUrl);
     log.fine("Loading transformers from $assetId");
 
     var port = new ReceivePort();