1 files changed, 90 insertions, 0 deletions
diff --git a/toolkit/jetpack/sdk/util/list.js b/toolkit/jetpack/sdk/util/list.js
new file mode 100644
index 000000000..6d7d2dea9
--- /dev/null
+++ b/toolkit/jetpack/sdk/util/list.js
@@ -0,0 +1,90 @@
+/* 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"
+};
+
+const { Class } = require('../core/heritage');
+const listNS = require('../core/namespace').ns();
+
+const listOptions = {
+  /**
+   * List constructor can take any number of element to populate itself.
+   * @params {Object|String|Number} element
+   * @example
+   *    List(1,2,3).length == 3 // true
+   */
+  initialize: function List() {
+    listNS(this).keyValueMap = [];
+
+    for (let i = 0, ii = arguments.length; i < ii; i++)
+      addListItem(this, arguments[i]);
+  },
+  /**
+   * Number of elements in this list.
+   * @type {Number}
+   */
+  get length() {
+    return listNS(this).keyValueMap.length;
+  },
+   /**
+    * Returns a string representing this list.
+    * @returns {String}
+    */
+  toString: function toString() {
+    return 'List(' + listNS(this).keyValueMap + ')';
+  },
+  /**
+   * Custom iterator providing `List`s enumeration behavior.
+   * We cant reuse `_iterator` that is defined by `Iterable` since it provides
+   * iteration in an arbitrary order.
+   * @see https://developer.mozilla.org/en/JavaScript/Reference/Statements/for...in
+   * @param {Boolean} onKeys
+   */
+  __iterator__: function __iterator__(onKeys, onKeyValue) {
+    let array = listNS(this).keyValueMap.slice(0),
+                i = -1;
+    for (let element of array)
+      yield onKeyValue ? [++i, element] : onKeys ? ++i : element;
+  },
+};
+listOptions[Symbol.iterator] = function iterator() {
+    return listNS(this).keyValueMap.slice(0)[Symbol.iterator]();
+};
+const List = Class(listOptions);
+exports.List = List;
+
+function addListItem(that, value) {
+  let list = listNS(that).keyValueMap,
+      index = list.indexOf(value);
+
+  if (-1 === index) {
+    try {
+      that[that.length] = value;
+    }
+    catch (e) {}
+    list.push(value);
+  }
+}
+exports.addListItem = addListItem;
+
+function removeListItem(that, element) {
+  let list = listNS(that).keyValueMap,
+      index = list.indexOf(element);
+
+  if (0 <= index) {
+    list.splice(index, 1);
+    try {
+      for (let length = list.length; index < length; index++)
+        that[index] = list[index];
+      that[list.length] = undefined;
+    }
+    catch(e){}
+  }
+}
+exports.removeListItem = removeListItem;
+
+exports.listNS = listNS;