Extend existing sass filesystem import to track dependencies

lib/sprockets/sass_importer.rb

@@ -1,103 +1,29 @@
+require 'sass'
+
 module Sprockets
   # This custom importer adds sprockets dependency tracking on to Sass
   # `@import` statements. This makes the Sprockets and Sass caching
   # systems work together.
-  class SassImporter
-    attr_reader :context
-
-    def initialize(context)
+  class SassImporter < Sass::Importers::Filesystem
+    def initialize(context, root)
       @context = context
+      super root.to_s
     end
 
-    def evaluate(pathname, options)
-      # Mark pathname as a dependency for cache tracking
-      context.depend_on_asset(pathname)
-
-      options = options.merge(:filename => pathname.to_s,  :syntax => :scss)
-      syntax  = pathname.extname[/\w+$/].to_sym
-
-      case syntax
-      when :sass, :scss
-        # `foo.sass` and `foo.scss` can be read directly by sass.
-        ::Sass::Engine.new(pathname.read, options.merge(:syntax => syntax))
-      else
-        # If the file something else like a `foo.css.erb`, have
-        # sprockets process it first before handing it off to sass.
-        ::Sass::Engine.new(context.evaluate(pathname), options)
-      end
-    end
-
-    # Find relative path to asset in load path and return its Pathname.
-    def resolve_relative(path, basepath)
-      dirname, basename = File.split(path)
-
-      # Ensure resolve is always called with a leading "./" to force a
-      # relative lookup.
-      if dirname == '.'
-        resolve("./_#{basename}", :base_path => basepath) ||
-          resolve("./#{basename}", :base_path => basepath)
-      else
-        resolve("./#{dirname}/_#{basename}", :base_path => basepath) ||
-          resolve("./#{dirname}/#{basename}", :base_path => basepath)
-      end
-    end
-
-    # Find full path to asset in load path and return its Pathname.
-    def resolve_loadpath(path)
-      return if path.to_s =~ /^\.\.?\//
-      dirname, basename = File.split(path)
-
-      # Strip any leading "./" to force a load path lookup.
-      if dirname == '.'
-        resolve("_#{basename}") || resolve("#{basename}")
-      else
-        resolve("#{dirname}/_#{basename}") || resolve("#{dirname}/#{basename}")
-      end
-    end
-
-    def resolve(path, options = {})
-      context.resolve(path, {:content_type => :self}.merge(options))
-    rescue Sprockets::FileNotFound
-      nil
-    end
-
-    # Find asset relative to the current file and return a `Sass::Engine`.
-    def find_relative(path, base, options)
-      if pathname = resolve_relative(path, :base_path => File.dirname(base))
-        evaluate(pathname, options)
-      end
-    end
-
-    # Find asset in Sprockets load path and return a `Sass::Engine`.
-    def find(path, options)
-      if pathname = resolve_loadpath(path)
-        evaluate(pathname, options)
+    def find_relative(*args)
+      engine = super
+      if engine && (filename = engine.options[:filename])
+        @context.depend_on_asset(filename)
       end
+      engine
     end
 
-    # Return mtime for path.
-    #
-    # (This method doesn't seem to ever be called)
-    def mtime(path, options)
-      if pathname = resolve_loadpath(path)
-        pathname.mtime
+    def find(*args)
+      engine = super
+      if engine && (filename = engine.options[:filename])
+        @context.depend_on_asset(filename)
       end
-    end
-
-    # Return cache key for Sass's cache system.
-    def key(name, options)
-      ["Sprockets:" + File.dirname(File.expand_path(name)), File.basename(name)]
-    end
-
-    # Pretty inspect
-    def inspect
-      "#<#{self.class}:0x#{object_id.to_s(16)} " +
-        "logical_path=#{context.logical_path.to_s.inspect}" +
-        ">"
-    end
-
-    def to_s
-      inspect
+      engine
     end
   end
 end

lib/sprockets/sass_template.rb

@@ -27,16 +27,15 @@ def syntax
 
     def evaluate(context, locals, &block)
       # Use custom importer that knows about Sprockets Caching
-      importer = SassImporter.new(context)
       cache_store = SassCacheStore.new(context.environment)
 
       options = {
         :filename => eval_file,
         :line => line,
         :syntax => syntax,
         :cache_store => cache_store,
-        :importer => importer,
-        :load_paths => [importer]
+        :importer => SassImporter.new(context, context.pathname),
+        :load_paths => context.environment.paths.map { |path| SassImporter.new(context, path) }
       }
 
       ::Sass::Engine.new(data, options).render

test/test_sass.rb

@@ -228,12 +228,4 @@ def render(path)
       @env[path].to_s
     end
   end
-
-  # For some reason Sass doesn't like importing other css files
-  test "@import css from scss" do
-    assert_equal <<-EOS, render('sass/import_css.scss')
-article, aside, details, figcaption, figure,\nfooter, header, hgroup, menu, nav, section {
-  display: block; }
-    EOS
-  end
 end