class Browser::Middleware

def call(env)
  request = Rack::Request.new(env)
  # Only apply verification on HTML requests.
  # This ensures that images, CSS and JavaScript
  # will be rendered.
  return run_app(env) unless process?(request)
  path = catch(:redirected) do
    Context.new(request).instance_eval(&@block)
  end
  # No path, no match.
  return run_app(env) unless path
  resolve_redirection(env, request.path, path)
end