1 files changed, 43 insertions, 0 deletions
diff --git a/tools/addon-sdk-1.7/packages/api-utils/lib/namespace.js b/tools/addon-sdk-1.7/packages/api-utils/lib/namespace.js
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+++ b/tools/addon-sdk-1.7/packages/api-utils/lib/namespace.js
@@ -0,0 +1,43 @@
+/* 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";
+
+// This is a temporary workaround until bug 673468 is fixed, which causes
+// entries associated with `XPCWrappedNative` wrapped keys to be GC-ed. To
+// workaround that we create a cross reference with an object from the same
+// compartment as `WeakMap` and use that as a key. Cross reference prevents
+// wrapper to be GC-ed until reference to it's value is kept.
+function handle(target) {
+  return target[handle.key] || Object.defineProperty(target, handle.key, {
+    value: { '::': target },
+    enumerable: false,
+    configurable: false,
+    writable: false
+  })[handle.key];
+}
+handle.key = '::ns::' + Math.round(Math.random() * 100000000000000000);
+
+/**
+ * Function creates a new namespace. Optionally `prototype` object may be
+ * passed, in which case namespace objects will inherit from it. Returned value
+ * is a function that can be used to get access to the namespaced properties
+ * for the passed object.
+ * @examples
+ *    const ns = Namespace();
+ *    ns(myObject).secret = secret;
+ */
+exports.Namespace = function Namespace(prototype) {
+  prototype = prototype || Object.prototype;
+  const map = new WeakMap();
+  return function namespace(target) {
+    let key = handle(target);
+    return map.get(key) ||
+           map.set(key, Object.create(prototype)), map.get(key);
+  };
+};
+
+// `Namespace` is a e4x function in the scope, so we export the function also as
+// `ns` as alias to avoid clashing.
+exports.ns = exports.Namespace;