Implement ActionView::Template::Types

AV::Template::Types is a small abstraction to allow to specify template types
that can be used in ActionView. When Action Pack is loaded it's replaced with
Mime::Type.

actionpack/lib/action_dispatch.rb

@@ -104,4 +104,5 @@ autoload :Mime, 'action_dispatch/http/mime_type'
 
 ActiveSupport.on_load(:action_view) do
   ActionView::Base.default_formats ||= Mime::SET.symbols
+  ActionView::Template::Types.delegate_to Mime
 end

actionpack/lib/action_view/template.rb

@@ -92,6 +92,7 @@ module ActionView
       autoload :Error
       autoload :Handlers
       autoload :Text
+      autoload :Types
     end
 
     extend Template::Handlers
@@ -121,7 +122,7 @@ module ActionView
       @locals            = details[:locals] || []
       @virtual_path      = details[:virtual_path]
       @updated_at        = details[:updated_at] || Time.now
-      @formats           = Array(format).map { |f| f.to_sym }
+      @formats           = Array(format).map { |f| f.respond_to?(:ref) ? f.ref : f  }
       @compile_mutex     = Mutex.new
     end
 
@@ -147,7 +148,7 @@ module ActionView
     end
 
     def type
-      @type ||= @formats.first.to_sym if @formats.first
+      @type ||= Types[@formats.first] if @formats.first
     end
 
     # Receives a view object and return a template similar to self by using @virtual_path.

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 && pieces.last.to_sym
+      format  = pieces.last && Template::Types[pieces.last]
       [handler, format]
     end
   end

actionpack/lib/action_view/template/text.rb

@@ -6,7 +6,8 @@ module ActionView #:nodoc:
 
       def initialize(string, type = nil)
         @string = string.to_s
-        @type = type || :text
+        @type   = Types[type] || type if type
+        @type ||= Types[:text]
       end
 
       def identifier

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