# File lib/compass/sass_extensions/functions/urls.rb, line 47
  def image_url(path, only_path = Sass::Script::Bool.new(false))
    path = path.value # get to the string value of the literal.

    if path =~ %r{^#{Regexp.escape(Compass.configuration.http_images_path)}/(.*)}
      # Treat root relative urls (without a protocol) like normal if they start with
      # the images path.
      path = $1
    elsif absolute_path?(path)
      # Short curcuit if they have provided an absolute url.
      return Sass::Script::String.new("url(#{path})")
    end

    # Compute the path to the image, either root relative or stylesheet relative
    # or nil if the http_images_path is not set in the configuration.
    http_images_path = if relative?
      compute_relative_path(Compass.configuration.images_dir)
    elsif Compass.configuration.http_images_path
      Compass.configuration.http_images_path
    else
      Compass.configuration.http_root_relative(Compass.configuration.images_dir)
    end

    # Compute the real path to the image on the file stystem if the images_dir is set.
    real_path = if Compass.configuration.images_dir
      File.join(Compass.configuration.project_path, Compass.configuration.images_dir, path)
    end

    # prepend the path to the image if there's one
    if http_images_path
      http_images_path = "#{http_images_path}/" unless http_images_path[-1..-1] == "/"
      path = "#{http_images_path}#{path}"
    end

    # Compute the asset host unless in relative mode.
    asset_host = if !relative? && Compass.configuration.asset_host
      Compass.configuration.asset_host.call(path)
    end

    # Compute and append the cache buster if there is one.
    if buster = compute_cache_buster(path, real_path)
      path += "?#{buster}"
    end

    # prepend the asset host if there is one.
    path = "#{asset_host}#{'/' unless path[0..0] == "/"}#{path}" if asset_host

    if only_path.to_bool
      Sass::Script::String.new(clean_path(path))
    else
      clean_url(path)
    end
  end