# File lib/rack/urlmap.rb, line 43
    def call(env)
      path = env[PATH_INFO]
      script_name = env['SCRIPT_NAME']
      hHost = env['HTTP_HOST']
      sName = env['SERVER_NAME']
      sPort = env['SERVER_PORT']

      @mapping.each do |host, location, match, app|
        unless casecmp?(hHost, host) \
            || casecmp?(sName, host) \
            || (!host && (casecmp?(hHost, sName) ||
                          casecmp?(hHost, sName+':'+sPort)))
          next
        end

        next unless m = match.match(path.to_s)

        rest = m[1]
        next unless !rest || rest.empty? || rest[0] == ?/

        env['SCRIPT_NAME'] = (script_name + location)
        env['PATH_INFO'] = rest

        return app.call(env)
      end

      [404, {CONTENT_TYPE => "text/plain", "X-Cascade" => "pass"}, ["Not Found: #{path}"]]

    ensure
      env['PATH_INFO'] = path
      env['SCRIPT_NAME'] = script_name
    end