Allow routing concerns to accept a callable

This allows us to make alterations to the generated routes based on the
scope of the current mapper, and otherwise allows us to move larger
blocks of concerns out of the routes file, altogether.

3 files changed, 34 insertions, 5 deletions

diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index b52f66faf1..b1abbbe505 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -1613,8 +1613,8 @@ module ActionDispatch
         #   end
         #
         # Any routing helpers can be used inside a concern.
-        def concern(name, &block)
-          @concerns[name] = block
+        def concern(name, callable = nil, &block)
+          @concerns[name] = callable || block
         end
 
         # Use the named concerns
@@ -1631,7 +1631,7 @@ module ActionDispatch
         def concerns(*names)
           names.flatten.each do |name|
             if concern = @concerns[name]
-              instance_eval(&concern)
+              concern.call(self)
             else
               raise ArgumentError, "No concern named #{name} was found!"
             end
@@ -1645,6 +1645,10 @@ module ActionDispatch
         @concerns = {}
       end
 
+      def current_scope
+        @scope
+      end
+
       include Base
       include HttpHelpers
       include Redirection
diff --git a/actionpack/test/abstract_unit.rb b/actionpack/test/abstract_unit.rb
index e5054a9eb8..4f5b2895c9 100644
--- a/actionpack/test/abstract_unit.rb
+++ b/actionpack/test/abstract_unit.rb
@@ -358,6 +358,7 @@ end
 class ThreadsController  < ResourcesController; end
 class MessagesController < ResourcesController; end
 class CommentsController < ResourcesController; end
+class ReviewsController < ResourcesController; end
 class AuthorsController < ResourcesController; end
 class LogosController < ResourcesController; end
 
diff --git a/actionpack/test/dispatch/routing/concerns_test.rb b/actionpack/test/dispatch/routing/concerns_test.rb
index 21da3bd77a..8600da32ad 100644
--- a/actionpack/test/dispatch/routing/concerns_test.rb
+++ b/actionpack/test/dispatch/routing/concerns_test.rb
@@ -1,6 +1,16 @@
 require 'abstract_unit'
 
 class RoutingConcernsTest < ActionDispatch::IntegrationTest
+  class Reviewable
+    def self.call(mapper)
+      if mapper.current_scope[:controller] == 'posts'
+        mapper.resources :reviews
+      elsif mapper.current_scope[:controller] == 'videos'
+        mapper.resources :reviews, as: :video_reviews
+      end
+    end
+  end
+
   Routes = ActionDispatch::Routing::RouteSet.new.tap do |app|
     app.draw do
       concern :commentable do
@@ -11,8 +21,10 @@ class RoutingConcernsTest < ActionDispatch::IntegrationTest
         resources :images, only: :index
       end
 
-      resources :posts, concerns: [:commentable, :image_attachable] do
-        resource :video, concerns: :commentable
+      concern :reviewable, Reviewable
+
+      resources :posts, concerns: [:commentable, :image_attachable, :reviewable] do
+        resource :video, concerns: [:commentable, :reviewable]
       end
 
       resource :picture, concerns: :commentable do
@@ -63,6 +75,18 @@ class RoutingConcernsTest < ActionDispatch::IntegrationTest
     assert_equal "404", @response.code
   end
 
+  def test_accessing_callable_concern_from_resources
+    get "/posts/1/reviews/1"
+    assert_equal "200", @response.code
+    assert_equal "/posts/1/reviews/1", post_review_path(post_id: 1, id: 1)
+  end
+
+  def test_callable_concern_can_adapt_to_mapper
+    get "/posts/1/video/reviews/1"
+    assert_equal "200", @response.code
+    assert_equal "/posts/1/video/reviews/1", post_video_video_review_path(post_id: 1, id: 1)
+  end
+
   def test_accessing_concern_from_a_scope
     get "/videos/comments"
     assert_equal "200", @response.code