Add partial implementation Native.addMenuItem.

It takes a path like "Menu 1 > Menu 2 > Item", and builds a series of submenus if needed along that path, then adds the final item at its terminus. Specs still need to be fleshed out further.

spec/stdlib/native-spec.coffee

@@ -0,0 +1,21 @@
+Native = require 'native'
+
+describe "Native", ->
+  nativeModule = null
+
+  beforeEach ->
+    nativeModule = new Native
+
+  fdescribe "addMenuItem(path, keyBinding)", ->
+    mainMenuItems = null
+
+    beforeEach ->
+      mainMenuItems = OSX.NSApp.mainMenu.itemArray
+
+    it "adds the item at the path terminus to the main menu, adding submenus as needed", ->
+      initialMenuCount = mainMenuItems.length
+
+      nativeModule.addMenuItem('Submenu > Item')
+
+      expect(mainMenuItems.length).toBe initialMenuCount + 1
+

src/stdlib/native.coffee

@@ -1,3 +1,5 @@
+_ = require 'underscore'
+
 module.exports =
 class Native
   alert: (message, detailedMessage, buttons) ->
@@ -43,3 +45,23 @@ class Native
   resetMainMenu: (menu) ->
     OSX.NSApp.resetMainMenu
 
+  addMenuItem: (path) ->
+    pathComponents = path.split /\s*>\s*/
+    submenu = @buildSubmenuPath(OSX.NSApp.mainMenu, pathComponents[0..-2])
+    title = _.last(pathComponents)
+    item = OSX.AtomMenuItem.alloc.initWithTitle_action_keyEquivalent(title, null, "").autorelease
+    submenu.addItem(item)
+
+  buildSubmenuPath: (menu, path) ->
+    return menu if path.length == 0
+
+    first = path[0]
+    unless item = menu.itemWithTitle(first)
+      item = OSX.AtomMenuItem.alloc.initWithTitle_action_keyEquivalent(first, null, "").autorelease
+      menu.addItem(item)
+    unless submenu = item.submenu
+      submenu = OSX.NSMenu.alloc.initWithTitle(first)
+      item.submenu = submenu
+
+    @buildSubmenuPath(submenu, path[1..-1])
+