Restore js interop code

lib/html/src/Isolates.dart

Index: lib/html/src/Isolates.dart
diff --git a/lib/html/src/Isolates.dart b/lib/html/src/Isolates.dart
index 3ad8c438c6adc75e78f368ef12bc3692845d475d..ea025abe571c56f81315e9ccef77e39e92e4b565 100644
--- a/lib/html/src/Isolates.dart
+++ b/lib/html/src/Isolates.dart
@@ -2,6 +2,272 @@
 // 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.
 
+_serialize(var message) {
+  return new _JsSerializer().traverse(message);
+}
+
+class _JsSerializer extends _Serializer {
+
+  visitSendPortSync(SendPortSync x) {
+    if (x is _JsSendPortSync) return visitJsSendPortSync(x);
+    if (x is _LocalSendPortSync) return visitLocalSendPortSync(x);
+    if (x is _RemoteSendPortSync) return visitRemoteSendPortSync(x);
+    throw "Illegal underlying port $x";
+  }
+
+  visitJsSendPortSync(_JsSendPortSync x) {
+    return [ 'sendport', 'nativejs', x._id ];
+  }
+
+  visitLocalSendPortSync(_LocalSendPortSync x) {
+    return [ 'sendport', 'dart',
+             ReceivePortSync._isolateId, x._receivePort._portId ];
+  }
+
+  visitRemoteSendPortSync(_RemoteSendPortSync x) {
+    return [ 'sendport', 'dart',
+             x._receivePort._isolateId, x._receivePort._portId ];
+  }
+
+  visitObject(Object x) {
+    if (x is Function) return visitFunction(x);
+    // TODO: Handle DOM elements and proxy other objects.
+    throw "Unserializable object $x";
+ }
+
+  visitFunction(Function func) {
+    return [ 'funcref',
+              _makeFunctionRef(func), visitSendPortSync(_sendPort()), null ];
+  }
+}
+
+// Leaking implementation.  Later will be backend specific and hopefully
+// not leaking (at least in most of the cases.)
+// TODO: provide better, backend specific implementation.
+class _FunctionRegistry {
+  final ReceivePortSync _port;
+  int _nextId;
+  final Map<String, Function> _registry;
+
+  _FunctionRegistry() :
+      _port = new ReceivePortSync(),
+      _nextId = 0,
+      _registry = <Function>{} {
+    _port.receive((msg) {
+      final id = msg[0];
+      final args = msg[1];
+      final f = _registry[id];
+      switch (args.length) {
+        case 0: return f();
+        case 1: return f(args[0]);
+        case 2: return f(args[0], args[1]);
+        case 3: return f(args[0], args[1], args[2]);
+        case 4: return f(args[0], args[1], args[2], args[3]);
+        default: throw 'Unsupported number of arguments.';
+      }
+    });
+  }
+
+  String _add(Function f) {
+    final id = 'func-ref-${_nextId++}';
+    _registry[id] = f;
+    return id;
+  }
+
+  get _sendPort() => _port.toSendPort();
+}
+
+_FunctionRegistry __functionRegistry;
+get _functionRegistry() {
+  if (__functionRegistry === null) __functionRegistry = new _FunctionRegistry();
+  return __functionRegistry;
+}
+
+_makeFunctionRef(f) => _functionRegistry._add(f);
+_sendPort() => _functionRegistry._sendPort;
+/// End of function serialization implementation.
+
+_deserialize(var message) {
+  return new _JsDeserializer().deserialize(message);
+}
+
+class _JsDeserializer extends _Deserializer {
+
+  static final _UNSPECIFIED = const Object();
+
+  deserializeSendPort(List x) {
+    String tag = x[1];
+    switch (tag) {
+      case 'nativejs':
+        num id = x[2];
+        return new _JsSendPortSync(id);
+      case 'dart':
+        num isolateId = x[2];
+        num portId = x[3];
+        return ReceivePortSync._lookup(isolateId, portId);
+      default:
+        throw 'Illegal SendPortSync type: $tag';
+    }
+  }
+
+  deserializeObject(List x) {
+    String tag = x[0];
+    switch (tag) {
+      case 'funcref': return deserializeFunction(x);
+      default: throw 'Illegal object type: $x';
+    }
+  }
+
+  deserializeFunction(List x) {
+    var id = x[1];
+    SendPortSync port = deserializeSendPort(x[2]);
+    // TODO: Support varargs when there is support in the language.
+    return ([arg0 = _UNSPECIFIED, arg1 = _UNSPECIFIED,
+              arg2 = _UNSPECIFIED, arg3 = _UNSPECIFIED]) {
+      var args = [arg0, arg1, arg2, arg3];
+      var last = args.indexOf(_UNSPECIFIED);
+      if (last >= 0) args = args.getRange(0, last);
+      var message = [id, args];
+      return port.callSync(message);
+    };
+  }
+}
+
+// The receiver is JS.
+class _JsSendPortSync implements SendPortSync {
+
+  num _id;
+  _JsSendPortSync(this._id);
+
+  callSync(var message) {
+    var serialized = _serialize(message);
+    var result = _callPortSync(_id, serialized);
+    return _deserialize(result);
+  }
+
+}
+
+// TODO(vsm): Differentiate between Dart2Js and Dartium isolates.
+// The receiver is a different Dart isolate, compiled to JS.
+class _RemoteSendPortSync implements SendPortSync {
+
+  int _isolateId;
+  int _portId;
+  _RemoteSendPortSync(this._isolateId, this._portId);
+
+  callSync(var message) {
+    var serialized = _serialize(message);
+    var result = _call(_isolateId, _portId, serialized);
+    return _deserialize(result);
+  }
+
+  static _call(int isolateId, int portId, var message) {
+    var target = 'dart-port-$isolateId-$portId'; 
+    // TODO(vsm): Make this re-entrant.
+    // TODO(vsm): Set this up set once, on the first call.
+    var source = '$target-result';
+    var result = null;
+    var listener = (TextEvent e) {
+      result = JSON.parse(e.data);
+    };
+    window.on[source].add(listener);
+    _dispatchEvent(target, [source, message]);
+    window.on[source].remove(listener);
+    return result;
+  }
+}
+
+// The receiver is in the same Dart isolate, compiled to JS.
+class _LocalSendPortSync implements SendPortSync {
+
+  ReceivePortSync _receivePort;
+
+  _LocalSendPortSync._internal(this._receivePort);
+
+  callSync(var message) {
+    // TODO(vsm): Do a more efficient deep copy.
+    var copy = _deserialize(_serialize(message));
+    var result = _receivePort._callback(copy);
+    return _deserialize(_serialize(result));
+  }
+}
+
+// TODO(vsm): Move this to dart:isolate.  This will take some
+// refactoring as there are dependences here on the DOM.  Users
+// interact with this class (or interface if we change it) directly -
+// new ReceivePortSync.  I think most of the DOM logic could be
+// delayed until the corresponding SendPort is registered on the
+// window.
+
+// A Dart ReceivePortSync (tagged 'dart' when serialized) is
+// identifiable / resolvable by the combination of its isolateid and
+// portid.  When a corresponding SendPort is used within the same
+// isolate, the _portMap below can be used to obtain the
+// ReceivePortSync directly.  Across isolates (or from JS), an
+// EventListener can be used to communicate with the port indirectly.
+class ReceivePortSync {
+
+  static Map<int, ReceivePortSync> _portMap;
+  static int _portIdCount;
+  static int _cachedIsolateId;
+
+  num _portId;
+  Function _callback;
+  EventListener _listener;
+
+  ReceivePortSync() {
+    if (_portIdCount == null) {
+      _portIdCount = 0;
+      _portMap = new Map<int, ReceivePortSync>();
+    }
+    _portId = _portIdCount++;
+    _portMap[_portId] = this;
+  }
+
+  static int get _isolateId() {
+    // TODO(vsm): Make this coherent with existing isolate code.
+    if (_cachedIsolateId == null) {
+      _cachedIsolateId = _getNewIsolateId();      
+    }
+    return _cachedIsolateId;
+  }
+
+  static String _getListenerName(isolateId, portId) =>
+      'dart-port-$isolateId-$portId'; 
+  String get _listenerName() => _getListenerName(_isolateId, _portId);
+
+  void receive(callback(var message)) {
+    _callback = callback;
+    if (_listener === null) {
+      _listener = (TextEvent e) {
+        var data = JSON.parse(e.data);
+        var replyTo = data[0];
+        var message = _deserialize(data[1]);
+        var result = _callback(message);
+        _dispatchEvent(replyTo, _serialize(result));
+      };
+      window.on[_listenerName].add(_listener);
+    }
+  }
+
+  void close() {
+    _portMap.remove(_portId);
+    if (_listener !== null) window.on[_listenerName].remove(_listener);
+  }
+
+  SendPortSync toSendPort() {
+    return new _LocalSendPortSync._internal(this);
+  }
+
+  static SendPortSync _lookup(int isolateId, int portId) {
+    if (isolateId == _isolateId) {
+      return _portMap[portId].toSendPort();
+    } else {
+      return new _RemoteSendPortSync(isolateId, portId);
+    }
+  }
+}
+
 void _dispatchEvent(String receiver, var message) {
   var event = document.$dom_createEvent('TextEvent');
   event.initTextEvent(receiver, false, false, window, JSON.stringify(message));