Bug 731779: Integrate the Add-on SDK loader and API libraries into Firefox (uplifting from addon-sdk a16bbd5772880b578a939eeb65102bca6560d494)

addon-sdk/source/lib/sdk/util/object.js

@@ -0,0 +1,57 @@
+/* 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": "unstable"
+};
+
+/**
+ * Merges all the properties of all arguments into first argument. If two or
+ * more argument objects have own properties with the same name, the property
+ * is overridden, with precedence from right to left, implying, that properties
+ * of the object on the left are overridden by a same named property of the
+ * object on the right.
+ *
+ * Any argument given with "falsy" value - commonly `null` and `undefined` in
+ * case of objects - are skipped.
+ *
+ * @examples
+ *    var a = { bar: 0, a: 'a' }
+ *    var b = merge(a, { foo: 'foo', bar: 1 }, { foo: 'bar', name: 'b' });
+ *    b === a   // true
+ *    b.a       // 'a'
+ *    b.foo     // 'bar'
+ *    b.bar     // 1
+ *    b.name    // 'b'
+ */
+function merge(source) {
+  let descriptor = {};
+  // `Boolean` converts the first parameter to a boolean value. Any object is
+  // converted to `true` where `null` and `undefined` becames `false`. Therefore
+  // the `filter` method will keep only objects that are defined and not null.
+  Array.slice(arguments, 1).filter(Boolean).forEach(function onEach(properties) {
+    Object.getOwnPropertyNames(properties).forEach(function(name) {
+      descriptor[name] = Object.getOwnPropertyDescriptor(properties, name);
+    });
+  });
+  return Object.defineProperties(source, descriptor);
+}
+exports.merge = merge;
+
+/**
+ * Returns an object that inherits from the first argument and contains all the
+ * properties from all following arguments.
+ * `extend(source1, source2, source3)` is equivalent of
+ * `merge(Object.create(source1), source2, source3)`.
+ */
+function extend(source) {
+  let rest = Array.slice(arguments, 1);
+  rest.unshift(Object.create(source));
+  return merge.apply(null, rest);
+}
+exports.extend = extend;
+
+