A Haml server for web designers

I have a script named serve in my bin directory that let's me quickly startup a Webrick server in any directory. This is handy for serving HTML mockups or other files. Today, updated it to work with Haml:

#!/usr/bin/env ruby
require 'webrick'
require 'rubygems'
require 'haml'
 
class HamlHandler < WEBrick::HTTPServlet::AbstractServlet
 
  def initialize(server, name)
    super
    @script_filename = name
  end
 
  def do_GET(req, res)
    begin
      data = open(@script_filename){|io| io.read }
      res.body = parse_haml(data)
      res['content-type'] = 'text/html'
    rescue StandardError => ex
      raise
    rescue Exception => ex
      @logger.error(ex)
      raise HTTPStatus::InternalServerError, ex.message
    end
  end
 
  alias do_POST do_GET
 
  private
    def parse_haml(string)
      engine = Haml::Engine.new(string,
        :attr_wrapper => '"',
        :filename => @script_filename
      )
      engine.render
    end
 
end
 
WEBrick::HTTPServlet::FileHandler.add_handler("haml", HamlHandler)
 
args = ARGV.join(' ')
args.gsub!(%r{^http://}, '')
args = args.split(/[ :]/).compact
 
server = WEBrick::HTTPServer.new(
  :Port => args.pop || 3000,
  :BindAddress => args.pop || '0.0.0.0',
  :DocumentRoot => Dir.pwd
)
 
trap("INT") { server.shutdown }
 
server.start