1 files changed, 20 insertions, 2 deletions
diff --git a/actionpack/lib/action_controller/routing_optimisation.rb b/actionpack/lib/action_controller/routing_optimisation.rb
index eaff1869dd..7cf85c9b9a 100644
--- a/actionpack/lib/action_controller/routing_optimisation.rb
+++ b/actionpack/lib/action_controller/routing_optimisation.rb
@@ -13,8 +13,8 @@ module ActionController
       def generate_optimisation_block(route, kind)
         return "" unless route.optimise?
         OPTIMISERS.inject("") do |memo, klazz|
-          optimiser = klazz.new(route, kind)
-          memo << "return #{optimiser.generation_code} if #{optimiser.guard_condition}\n"
+          memo << klazz.new(route, kind).source_code
+          memo
         end
       end
 
@@ -32,6 +32,18 @@ module ActionController
         def generation_code
           'nil'
         end
+
+        def source_code
+          if applicable?
+            "return #{generation_code} if #{guard_condition}\n"
+          else
+            "\n"
+          end
+        end
+
+        def applicable?
+          true
+        end
       end
 
       # Given a route:
@@ -89,6 +101,12 @@ module ActionController
         def generation_code
           super.insert(-2, '?#{args.last.to_query}')
         end
+
+        # To avoid generating http://localhost/?host=foo.example.com we
+        # can't use this optimisation on routes without any segments
+        def applicable?
+          route.segment_keys.size > 0 
+        end
       end
 
       OPTIMISERS = [PositionalArguments, PositionalArgumentsWithAdditionalParams]