1 files changed, 64 insertions, 0 deletions
diff --git a/toolkit/jetpack/dev/ports.js b/toolkit/jetpack/dev/ports.js
new file mode 100644
index 000000000..a41f59eb7
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+++ b/toolkit/jetpack/dev/ports.js
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+module.metadata = {
+  "stability": "experimental"
+};
+
+// This module provides `marshal` and `demarshal` functions
+// that can be used to send  MessagePort's over `nsIFrameMessageManager`
+// until Bug 914974 is fixed.
+
+const { add, iterator } = require("../sdk/lang/weak-set");
+const { curry } = require("../sdk/lang/functional");
+
+var id = 0;
+const ports = new WeakMap();
+
+// Takes `nsIFrameMessageManager` and `MessagePort` instances
+// and returns a handle representing given `port`. Messages
+// received on given `port` will be forwarded to a message
+// manager under `sdk/port/message` and messages like:
+// { port: { type: "MessagePort", id: 2}, data: data }
+// Where id is an identifier associated with a given `port`
+// and `data` is an `event.data` received on port.
+const marshal = curry((manager, port) => {
+  if (!ports.has(port)) {
+    id = id + 1;
+    const handle = {type: "MessagePort", id: id};
+    // Bind id to the given port
+    ports.set(port, handle);
+
+    // Obtain a weak reference to a port.
+    add(exports, port);
+
+    port.onmessage = event => {
+      manager.sendAsyncMessage("sdk/port/message", {
+        port: handle,
+        message: event.data
+      });
+    };
+
+    return handle;
+  }
+  return ports.get(port);
+});
+exports.marshal = marshal;
+
+// Takes `nsIFrameMessageManager` instance and a handle returned
+// `marshal(manager, port)` returning a `port` that was passed
+// to it. Note that `port` may be GC-ed in which case returned
+// value will be `null`.
+const demarshal = curry((manager, {type, id}) => {
+  if (type === "MessagePort") {
+    for (let port of iterator(exports)) {
+      if (id === ports.get(port).id)
+        return port;
+    }
+  }
+  return null;
+});
+exports.demarshal = demarshal;