This commit merges most of the work done by Piotr Sarnacki in his Ruby Summer of Code project.

His work brings several capabilities from app to engines, as routes, middleware stack, asset handling and much more. Please check Rails::Engine documentation for more refenrences.

Merge remote branch 'drogus/engines'

3 files changed, 47 insertions, 0 deletions

diff --git a/actionpack/lib/abstract_controller/railties/routes_helpers.rb b/actionpack/lib/abstract_controller/railties/routes_helpers.rb
new file mode 100644
index 0000000000..dec1e9d6d9
--- /dev/null
+++ b/actionpack/lib/abstract_controller/railties/routes_helpers.rb
@@ -0,0 +1,18 @@
+module AbstractController
+  module Railties
+    module RoutesHelpers
+      def self.with(routes)
+        Module.new do
+          define_method(:inherited) do |klass|
+            super(klass)
+            if namespace = klass.parents.detect {|m| m.respond_to?(:_railtie) }
+              klass.send(:include, namespace._railtie.routes.url_helpers)
+            else
+              klass.send(:include, routes.url_helpers)
+            end
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/actionpack/lib/abstract_controller/rendering.rb b/actionpack/lib/abstract_controller/rendering.rb
index b81d5954eb..5d9b35d297 100644
--- a/actionpack/lib/abstract_controller/rendering.rb
+++ b/actionpack/lib/abstract_controller/rendering.rb
@@ -52,6 +52,7 @@ module AbstractController
 
               if controller.respond_to?(:_routes)
                 include controller._routes.url_helpers
+                include controller._routes.mounted_helpers
               end
 
               # TODO: Fix RJS to not require this
diff --git a/actionpack/lib/abstract_controller/url_for.rb b/actionpack/lib/abstract_controller/url_for.rb
new file mode 100644
index 0000000000..2e9de22ecd
--- /dev/null
+++ b/actionpack/lib/abstract_controller/url_for.rb
@@ -0,0 +1,28 @@
+module AbstractController
+  module UrlFor
+    extend ActiveSupport::Concern
+
+    include ActionDispatch::Routing::UrlFor
+
+    def _routes
+      raise "In order to use #url_for, you must include routing helpers explicitly. " \
+            "For instance, `include Rails.application.routes.url_helpers"
+    end
+
+    module ClassMethods
+      def _routes
+        nil
+      end
+
+      def action_methods
+        @action_methods ||= begin
+          if _routes
+            super - _routes.named_routes.helper_names
+          else
+            super
+          end
+        end
+      end
+    end
+  end
+end