module Sinatra::Templates

def lookup_template(engine, template, options={})
  case template
  when Symbol
    if cached = self.class.templates[template]
      lookup_template(engine, cached, options)
    else
      ::File.read(template_path(engine, template, options))
    end
  when Proc
    template.call
  when String
    template
  else
    raise ArgumentError
  end
end