# File lib/compass/compiler.rb, line 204
    def engine(sass_filename, css_filename, sourcemap_filename = nil)
      syntax = (sass_filename =~ /\.(s[ac]ss)$/) && $1.to_sym || :sass
      opts = sass_options.merge(:filename => sass_filename,
                                :css_filename => css_filename,
                                :syntax => syntax,
                                :sourcemap_filename => sourcemap_filename)
      Sass::Engine.new(open(sass_filename).read, opts)
    end