converts uri w/ placeholder to regexp
          '/cars/{carName}/drivers/{DriverName}'
        -> '^/cars/.*/drivers/[^/]*$'

          '/cars/{carName}/drivers/{DriverName}/drive'
        -> '^/cars/.*/drivers/.*/drive$'

def uri_to_regexp(self, uri):
        """converts uri w/ placeholder to regexp
          '/cars/{carName}/drivers/{DriverName}'
        -> '^/cars/.*/drivers/[^/]*$'

          '/cars/{carName}/drivers/{DriverName}/drive'
        -> '^/cars/.*/drivers/.*/drive$'

        """
        def _convert(elem, is_last):
            if not re.match('^{.*}$', elem):
                return elem
            name = elem.replace('{', '').replace('}', '')
            if is_last:
                return '(?P<%s>[^/]*)' % name
            return '(?P<%s>.*)' % name

        elems = uri.split('/')
        num_elems = len(elems)
        regexp = '^{}$'.format('/'.join([_convert(elem, (i == num_elems - 1)) for i, elem in enumerate(elems)]))
        return regexp