gistfile1.rb

### /lib/rack/sass ###
require 'sass'

module Rack
  class Sass < Rack::File
    def initialize(root, options = {})
      @root = root
      @options = options
    end
    
    def _call(env)
      @path_info = Utils.unescape(env["PATH_INFO"])
      return forbidden  if @path_info.include? ".."
      return forbidden  unless @path_info.include? ".css"
      
      @path = F.join(@root, @path_info).gsub(/\.css/, '.sass')

      begin
        if F.file?(@path) && F.readable?(@path)
          serving
        else
          raise Errno::EPERM
        end
      rescue SystemCallError
        not_found
      end
    end
    
    def serving
      body = ::Sass::Engine.new(F.read(@path), @options).render
      [200, {
        "Last-Modified"  => F.mtime(@path).httpdate,
        "Content-Type"   => Mime.mime_type(".css"),
        "Content-Length" => Utils.bytesize(body).to_s
      }, [body]]
    end
  end
end