Adding Sprockets-aware caching

lib/sprockets/sass.rb

@@ -5,7 +5,8 @@
 
 module Sprockets
   module Sass
-    autoload :Importer, "sprockets/sass/importer"
+    autoload :CacheStore, "sprockets/sass/cache_store"
+    autoload :Importer,   "sprockets/sass/importer"
 
     class << self
       # Global configuration for `Sass::Engine` instances.

lib/sprockets/sass/cache_store.rb

@@ -0,0 +1,27 @@
+require "sass"
+
+module Sprockets
+  module Sass
+    class CacheStore < ::Sass::CacheStores::Base
+      attr_reader :environment
+
+      def initialize(environment)
+        @environment = environment
+      end
+
+      def _store(key, version, sha, contents)
+        environment.send :cache_set, "sass/#{key}", { :version => version, :sha => sha, :contents => contents }
+      end
+
+      def _retrieve(key, version, sha)
+        if obj = environment.send(:cache_get, "sass/#{key}")
+          return unless obj[:version] == version
+          return unless obj[:sha] == sha
+          obj[:obj]
+        else
+          nil
+        end
+      end
+    end
+  end
+end

lib/sprockets/sass/sass_template.rb

@@ -8,7 +8,7 @@ class SassTemplate < Tilt::SassTemplate
       # A reference to the current Sprockets context
       attr_reader :context
 
-      # Templates are initialized once the 
+      # Templates are initialized once the functions are added.
       def self.engine_initialized?
         super && defined?(@@sass_functions_added)
       end
@@ -46,6 +46,17 @@ def evaluate(context, locals, &block)
 
       protected
 
+      # Returns a Sprockets-aware cache store for Sass::Engine.
+      def cache_store
+        return nil if context.environment.nil?
+
+        if defined?(Sprockets::SassCacheStore)
+          Sprockets::SassCacheStore.new context.environment
+        else
+          CacheStore.new context.environment
+        end
+      end
+
       # A reference to the custom Sass importer, `Sprockets::Sass::Importer`.
       def importer
         Importer.new context
@@ -54,10 +65,11 @@ def importer
       # Assemble the options for the `Sass::Engine`
       def sass_options
         merge_sass_options(default_sass_options, options).merge(
-          :filename => eval_file,
-          :line     => line,
-          :syntax   => syntax,
-          :importer => importer
+          :filename    => eval_file,
+          :line        => line,
+          :syntax      => syntax,
+          :cache_store => cache_store,
+          :importer    => importer
         )
       end
 

spec/sprockets-sass_spec.rb

@@ -181,6 +181,17 @@
     asset.should_not be_fresh(@env)
   end
 
+  it "uses the environment's cache" do
+    cache = {}
+    @env.cache = cache
+
+    @assets.file "main.css.scss", %($color: blue;;\nbody { color: $color; })
+
+    @env['main.css'].to_s
+    sass_cache = cache.keys.detect { |key| key =~ /main\.css\.scss/ }
+    sass_cache.should_not be_nil
+  end
+
   it "adds the #asset_path helper" do
     @assets.file "asset_path.css.scss", %(body { background: url(asset-path("image.jpg")); })
     @assets.file "asset_url.css.scss", %(body { background: asset-url("image.jpg"); })