5 files changed, 69 insertions, 8 deletions
diff --git a/actionpack/lib/action_view/template/error.rb b/actionpack/lib/action_view/template/error.rb
index f2bef4bded..e00056781d 100644
--- a/actionpack/lib/action_view/template/error.rb
+++ b/actionpack/lib/action_view/template/error.rb
@@ -8,6 +8,9 @@ module ActionView
   class EncodingError < StandardError #:nodoc:
   end
 
+  class MissingRequestError < StandardError #:nodoc:
+  end
+
   class WrongEncodingError < EncodingError #:nodoc:
     def initialize(string, encoding)
       @string, @encoding = string, encoding
diff --git a/actionpack/lib/action_view/template/handlers/builder.rb b/actionpack/lib/action_view/template/handlers/builder.rb
index 34397c3bcf..d90b0c6378 100644
--- a/actionpack/lib/action_view/template/handlers/builder.rb
+++ b/actionpack/lib/action_view/template/handlers/builder.rb
@@ -3,7 +3,7 @@ module ActionView
     class Builder
       # Default format used by Builder.
       class_attribute :default_format
-      self.default_format = Mime::XML
+      self.default_format = :xml
 
       def call(template)
         require_engine
diff --git a/actionpack/lib/action_view/template/resolver.rb b/actionpack/lib/action_view/template/resolver.rb
index 2bb656fac9..25c6fd4aa8 100644
--- a/actionpack/lib/action_view/template/resolver.rb
+++ b/actionpack/lib/action_view/template/resolver.rb
@@ -235,7 +235,7 @@ module ActionView
       extension = pieces.pop
       ActiveSupport::Deprecation.warn "The file #{path} did not specify a template handler. The default is currently ERB, but will change to RAW in the future." unless extension
       handler = Template.handler_for_extension(extension)
-      format  = pieces.last && Mime[pieces.last]
+      format  = pieces.last && Template::Types[pieces.last]
       [handler, format]
     end
   end
diff --git a/actionpack/lib/action_view/template/text.rb b/actionpack/lib/action_view/template/text.rb
index 3af76dfcdb..859c7bc3ce 100644
--- a/actionpack/lib/action_view/template/text.rb
+++ b/actionpack/lib/action_view/template/text.rb
@@ -2,12 +2,12 @@ module ActionView #:nodoc:
   # = Action View Text Template
   class Template
     class Text #:nodoc:
-      attr_accessor :mime_type
+      attr_accessor :type
 
-      def initialize(string, mime_type = nil)
-        @string      = string.to_s
-        @mime_type   = Mime[mime_type] || mime_type if mime_type
-        @mime_type ||= Mime::TEXT
+      def initialize(string, type = nil)
+        @string = string.to_s
+        @type   = Types[type] || type if type
+        @type ||= Types[:text]
       end
 
       def identifier
@@ -27,7 +27,7 @@ module ActionView #:nodoc:
       end
 
       def formats
-        [@mime_type.to_sym]
+        [@type.to_sym]
       end
     end
   end
diff --git a/actionpack/lib/action_view/template/types.rb b/actionpack/lib/action_view/template/types.rb
new file mode 100644
index 0000000000..7611c9e708
--- /dev/null
+++ b/actionpack/lib/action_view/template/types.rb
@@ -0,0 +1,58 @@
+require 'set'
+require 'active_support/core_ext/class/attribute_accessors'
+require 'active_support/core_ext/object/blank'
+
+module ActionView
+  class Template
+    class Types
+      class Type
+        cattr_accessor :types
+        self.types = Set.new
+
+        def self.register(*t)
+          types.merge(t.map { |type| type.to_s })
+        end
+
+        register :html, :text, :js, :css,  :xml, :json
+
+        def self.[](type)
+          return type if type.is_a?(self)
+
+          if type.is_a?(Symbol) || types.member?(type.to_s)
+            new(type)
+          end
+        end
+
+        attr_reader :symbol
+
+        def initialize(symbol)
+          @symbol = symbol.to_sym
+        end
+
+        delegate :to_s, :to_sym, :to => :symbol
+        alias to_str to_s
+
+        def ref
+          to_sym || to_s
+        end
+
+        def ==(type)
+          return false if type.blank?
+          symbol.to_sym == type.to_sym
+        end
+      end
+
+      cattr_accessor :type_klass
+
+      def self.delegate_to(klass)
+        self.type_klass = klass
+      end
+
+      delegate_to Type
+
+      def self.[](type)
+        type_klass[type]
+      end
+    end
+  end
+end