def _process_origin(self, req, resp, origin):
        """Inspects the request and adds the Access-Control-Allow-Origin
        header if the requested origin is allowed.

        Returns:
            ``True`` if the header was added and the requested origin
            is allowed, ``False`` if the origin is not allowed and the
            header has not been added.
        """
        if self._cors_config['allow_all_origins']:
            if self.supports_credentials:
                self._set_allow_origin(resp, origin)
            else:
                self._set_allow_origin(resp, '*')
            return True

        if origin in self._cors_config['allow_origins_list']:
            self._set_allow_origin(resp, origin)
            return True

        regex = self._cors_config['allow_origins_regex']
        if regex is not None:
            if regex.match(origin):
                self._set_allow_origin(resp, origin)
                return True

        return False
Inspects the request and adds the Access-Control-Allow-Origin
        header if the requested origin is allowed.

        Returns:
            ``True`` if the header was added and the requested origin
            is allowed, ``False`` if the origin is not allowed and the
            header has not been added.