1 files changed, 40 insertions, 16 deletions

diff --git a/actionpack/lib/sprockets/helpers/rails_helper.rb b/actionpack/lib/sprockets/helpers/rails_helper.rb
index 9f1f0f3b68..a95e7c0649 100644
--- a/actionpack/lib/sprockets/helpers/rails_helper.rb
+++ b/actionpack/lib/sprockets/helpers/rails_helper.rb
@@ -1,4 +1,4 @@
-require "action_view/helpers"
+require "action_view"
 
 module Sprockets
   module Helpers
@@ -9,8 +9,12 @@ module Sprockets
       def asset_paths
         @asset_paths ||= begin
           config     = self.config if respond_to?(:config)
+          config   ||= Rails.application.config
           controller = self.controller if respond_to?(:controller)
-          RailsHelper::AssetPaths.new(config, controller)
+          paths = RailsHelper::AssetPaths.new(config, controller)
+          paths.asset_environment = asset_environment
+          paths.asset_prefix      = asset_prefix
+          paths
         end
       end
 
@@ -50,7 +54,7 @@ module Sprockets
               'rel'   => "stylesheet",
               'type'  => "text/css",
               'media' => "screen",
-              'href'  => asset_path(source, 'css', body)
+              'href'  => asset_path(source, 'css', body, :request)
             }.merge(options.stringify_keys)
 
             tag 'link', tag_options
@@ -58,35 +62,59 @@ module Sprockets
         end.join("\n").html_safe
       end
 
+      def asset_path(source, default_ext = nil, body = false, protocol = nil)
+        source = source.logical_path if source.respond_to?(:logical_path)
+        path = asset_paths.compute_public_path(source, 'assets', default_ext, true, protocol)
+        body ? "#{path}?body=1" : path
+      end
+
     private
       def debug_assets?
         params[:debug_assets] == '1' ||
           params[:debug_assets] == 'true'
       end
 
-      def asset_path(source, default_ext = nil, body = false)
-        source = source.logical_path if source.respond_to?(:logical_path)
-        path = asset_paths.compute_public_path(source, Rails.application.config.assets.prefix, default_ext, true)
-        body ? "#{path}?body=1" : path
+      # Override to specify an alternative prefix for asset path generation.
+      # When combined with a custom +asset_environment+, this can be used to
+      # implement themes that can take advantage of the asset pipeline.
+      #
+      # If you only want to change where the assets are mounted, refer to
+      # +config.assets.prefix+ instead.
+      def asset_prefix
+        Rails.application.config.assets.prefix
+      end
+
+      # Override to specify an alternative asset environment for asset
+      # path generation. The environment should already have been mounted
+      # at the prefix returned by +asset_prefix+.
+      def asset_environment
+        Rails.application.assets
       end
 
       class AssetPaths < ::ActionView::AssetPaths #:nodoc:
-        def compute_public_path(source, dir, ext=nil, include_host=true)
-          super(source, Rails.application.config.assets.prefix, ext, include_host)
+        attr_accessor :asset_environment, :asset_prefix
+
+        def compute_public_path(source, dir, ext=nil, include_host=true, protocol=nil)
+          super(source, asset_prefix, ext, include_host, protocol)
+        end
+
+        # Return the filesystem path for the source
+        def compute_source_path(source, ext)
+          asset_for(source, ext)
         end
 
         def asset_for(source, ext)
           source = source.to_s
           return nil if is_uri?(source)
           source = rewrite_extension(source, nil, ext)
-          assets[source]
+          asset_environment[source]
         end
 
         def rewrite_asset_path(source, dir)
           if source[0] == ?/
             source
           else
-            assets.path(source, performing_caching?, dir)
+            asset_environment.path(source, performing_caching?, dir)
           end
         end
 
@@ -98,13 +126,9 @@ module Sprockets
           end
         end
 
-        def assets
-          Rails.application.assets
-        end
-
         # When included in Sprockets::Context, we need to ask the top-level config as the controller is not available
         def performing_caching?
-          @config ?  @config.perform_caching : Rails.application.config.action_controller.perform_caching
+          config.action_controller.present? ? config.action_controller.perform_caching : config.perform_caching
         end
       end
     end