Support proxying of objects between JS and Dart.

client/dart.js

Index: client/dart.js
diff --git a/client/dart.js b/client/dart.js
index 711aeee5702478258e964aad47a196e109154701..1985ee133b7c5452763c32ee3a42130968d9ebb6 100644
--- a/client/dart.js
+++ b/client/dart.js
@@ -46,31 +46,66 @@ function ReceivePortSync() {
 }
 
 (function() {
-  // Track proxied functions.
-  // TODO: Fix leaks, particularly in dart2js case.
-  var functionRefMap = {};
-
-  var nextFunctionRefId = 0;
-
-  function functionRefDispatch(message) {
-    var id = message[0];
-    var args = message[1];
-    var f = functionRefMap[id];
-    // TODO: Should we capture this automatically?
-    return f.apply(null, args);
+  function RefTable(name) {
+    // TODO: Fix leaks, particularly in dart2js case.

[Emily Fortuna, 2012/08/21 23:39:56]

TODO(vsm):

[vsm, 2012/08/22 00:04:28]

Done.

+    this.name = name;
+    this.map = {};
+    this.id = 0;
+    this.initialized = false;
+  }
+  
+  RefTable.prototype.nextId = function () { return this.id++; }
+
+  RefTable.prototype.makeRef = function (obj) {
+    this.initializeOnce();
+    // TODO: Cache refs for each obj.

[Emily Fortuna, 2012/08/21 23:39:56]

add username to TODO :-)

[vsm, 2012/08/22 00:04:28]

Done.

+    var ref = this.name + '-' + this.nextId();
+    this.map[ref] = obj;

[Emily Fortuna, 2012/08/21 23:39:56]

Is this for improved debugging experience (could be useful)? If not, why not
just use an array, where nextId is the index number into the array? 

[vsm, 2012/08/22 00:04:28]

Primarily debugging ease.  Makes it easier to tell where the ref came from than
just a number.

On 2012/08/21 23:39:56, Emily Fortuna wrote:

+    return ref;
   }
 
-  var functionRefPort = null;
-
-  function makeFunctionRef(f) {
-    if (functionRefPort == null) {
-      var port = new ReceivePortSync();
-      port.receive(functionRefDispatch);
-      functionRefPort = port.toSendPort();
+  RefTable.prototype.initializeOnce = function () {
+    if (!this.initialized) {
+      this.initialize();
     }
-    var ref = 'func-ref-' + (nextFunctionRefId++);
-    functionRefMap[ref] = f;
-    return ref;
+    this.initialized = true;
+  }
+
+  // Overridable initialization on first use hook.
+  RefTable.prototype.initialize = function () {
+  }

[Emily Fortuna, 2012/08/21 23:39:56]

move this up to the previous line?
http://www.corp.google.com/eng/doc/javascriptguide.xml?showone=Method_definit...

[vsm, 2012/08/22 00:04:28]

Done.

+
+  RefTable.prototype.get = function (ref) {
+    return this.map[ref];
+  }
+
+  function FunctionRefTable() {
+  }

[Emily Fortuna, 2012/08/21 23:39:56]

probably can move this } up onto the previous line

[vsm, 2012/08/22 00:04:28]

Done.

+  FunctionRefTable.prototype = new RefTable('func-ref');
+
+  FunctionRefTable.prototype.initialize = function () {
+    var receivePort = new ReceivePortSync();
+    map = this.map;
+    receivePort.receive(function (message) {
+      var id = message[0];
+      var args = message[1];
+      var f = map[id];
+      // TODO: Should we capture this automatically?

[Emily Fortuna, 2012/08/21 23:39:56]

TODO(vsm):

[vsm, 2012/08/22 00:04:28]

Done.

+      return f.apply(null, args);    
+    });
+    this.port = receivePort.toSendPort();
+  }
+
+  var functionRefTable = new FunctionRefTable();
+
+  function JSRefTable() {
+  }
+  JSRefTable.prototype = new RefTable('js-ref');

[Emily Fortuna, 2012/08/21 23:39:56]

add an extra whitespace line above

[vsm, 2012/08/22 00:04:28]

Done.

+  var jsRefTable = new JSRefTable();
+
+  function DartProxy(id) {
+    // TODO(vsm): Set isolate id.
+    this.id = id;
   }
 
   function serialize(message) {
@@ -107,8 +142,14 @@ function ReceivePortSync() {
       } else if (message instanceof DartSendPortSync) {
         return [ 'sendport', 'dart', message.isolateId, message.portId ];
       } else if (message instanceof Function) {
-        return [ 'funcref', makeFunctionRef(message),
-                 doSerialize(functionRefPort) ];
+        return [ 'funcref', functionRefTable.makeRef(message),
+                 doSerialize(functionRefTable.port) ];
+      } else if (message instanceof DartProxy) {
+        return [ 'objref', 'dart', message.id ];
+      } else if (message.__proto__ != {}.__proto) {
+	// TODO(vsm): Is the above portable and what we want?

[Emily Fortuna, 2012/08/21 23:39:56]

remove tabs here

[vsm, 2012/08/22 00:04:28]

Done.

+	// Proxy non-map Objects.
+        return [ 'objref', 'nativejs', jsRefTable.makeRef(message) ];

[Emily Fortuna, 2012/08/21 23:39:56]

I thought all objects in JS could be examined as maps (?)

[vsm, 2012/08/22 00:04:28]

Right.  The proto check in the preceding if is trying to differentiate between
maps created like "{'a': 1}" and ones that look more like objects.  Still not
sure this is the best way to go about this.

On 2012/08/21 23:39:56, Emily Fortuna wrote:

       } else {
         return checkedSerialization(message, function(id) {
           var keys = Object.getOwnPropertyNames(message);
@@ -139,6 +180,7 @@ function ReceivePortSync() {
       case 'sendport': return deserializeSendPort(x);
       case 'list': return deserializeList(x);
       case 'funcref': return deserializeFunction(x);
+      case 'objref': return deserializeProxy(x);
       default: throw 'unimplemented';
     }
   }
@@ -189,6 +231,18 @@ function ReceivePortSync() {
     return _makeFunctionFromRef(ref, sendPort);
   }
 
+  function deserializeProxy(x) {
+    var tag = x[1];
+    if (tag == 'nativejs') {
+      var id = x[2];
+      return jsRefTable.map[id];
+    } else if (tag == 'dart') {
+      var id = x[2];
+      return new DartProxy(id);
+    }
+    throw 'Illegal proxy object: ' + x;
+  }
+
   window.registerPort = function(name, port) {
     var stringified = JSON.stringify(serialize(port));
     window.localStorage['dart-port:' + name] = stringified;