Initial work to merge several places with similar logic

actionpack/lib/action_controller/mime_responds.rb

@@ -109,16 +109,13 @@ def respond_to(*types, &block)
     end
 
     class Responder #:nodoc:
+      
       def initialize(controller)
         @controller = controller
         @request    = controller.request
         @response   = controller.response
 
-        if ActionController::Base.use_accept_header
-          @mime_type_priority = Array(Mime::Type.lookup_by_extension(@request.parameters[:format]) || @request.accepts)
-        else
-          @mime_type_priority = [@request.format]
-        end
+        @mime_type_priority = @request.formats
 
         @order     = []
         @responses = {}

actionpack/lib/action_controller/mime_type.rb

@@ -5,6 +5,10 @@ module Mime
   EXTENSION_LOOKUP = Hash.new { |h, k| h[k] = Type.new(k) unless k.blank? }
   LOOKUP           = Hash.new { |h, k| h[k] = Type.new(k) unless k.blank? }
 
+  def self.[](type)
+    Type.lookup_by_extension(type)
+  end
+
   # Encapsulates the notion of a mime type. Can be used at render time, for example, with:
   #
   #   class PostsController < ActionController::Base

actionpack/lib/action_controller/request.rb

@@ -152,24 +152,33 @@ def fresh?(response)
       end
     end
 
+    ONLY_ALL = [Mime::ALL].freeze
+
     # Returns the Mime type for the \format used in the request.
     #
     #   GET /posts/5.xml   | request.format => Mime::XML
     #   GET /posts/5.xhtml | request.format => Mime::HTML
     #   GET /posts/5       | request.format => Mime::HTML or MIME::JS, or request.accepts.first depending on the value of <tt>ActionController::Base.use_accept_header</tt>
+
     def format
       @format ||=
         if parameters[:format]
-          Mime::Type.lookup_by_extension(parameters[:format])
-        elsif ActionController::Base.use_accept_header
-          accepts.first
-        elsif xhr?
-          Mime::Type.lookup_by_extension("js")
-        else
-          Mime::Type.lookup_by_extension("html")
+                        Mime[parameters[:format]]
+        elsif Base.use_accept_header && !(accepts == ONLY_ALL)
+                        accepts.first
+        elsif xhr? then Mime::JS
+        else            Mime::HTML
         end
     end
 
+    def formats
+      @formats = 
+        if Base.use_accept_header
+          Array(Mime[parameters[:format]] || accepts)
+        else
+          [format]
+        end
+    end
 
     # Sets the \format by string extension, which can be used to force custom formats
     # that are not controlled by the extension.

actionpack/lib/action_view/base.rb

@@ -266,7 +266,7 @@ def template_format
       if defined? @template_format
         @template_format
       elsif controller && controller.respond_to?(:request)
-        @template_format = controller.request.template_format.to_sym
+        @template_format = controller.request.format.to_sym
       else
         @template_format = :html
       end