"""

        return _re.match(came_from) is not None

    def index(self):

        c.came_from = safe_str(request.GET.get('came_from', ''))

        if c.came_from:

            if not self._validate_came_from(c.came_from):

                log.error('Invalid came_from (not server-relative): %r', c.came_from)

                raise HTTPBadRequest()

        else:

            c.came_from = url('home')

        if request.POST:

            # import Login Form validator class

            login_form = LoginForm()()

            try:

                c.form_result = login_form.to_python(dict(request.POST))

                # form checks for username/password, now we're authenticated

                username = c.form_result['username']

                user = User.get_by_username_or_email(username, case_insensitive=True)

            except formencode.Invalid as errors:

                defaults = errors.value

                # remove password from filling in form again

                defaults.pop('password', None)

                    encoding="UTF-8",

                    force_defaults=False)

            except UserCreationError as e:

                # container auth or other auth functions that create users on

                # the fly can throw this exception signaling that there's issue

                # with user creation, explanation should be provided in

                # Exception itself

                h.flash(e, 'error')

            else:

                log_in_user(user, c.form_result['remember'],

                    is_external_auth=False)

                raise HTTPFound(location=c.came_from)

        return render('/login.html')

    @HasPermissionAnyDecorator('hg.admin', 'hg.register.auto_activate',

                               'hg.register.manual_activate')

    def register(self):

        def_user_perms = AuthUser(dbuser=User.get_default_user()).permissions['global']

        c.auto_active = 'hg.register.auto_activate' in def_user_perms

        settings = Setting.get_app_settings()

        captcha_private_key = settings.get('captcha_private_key')

        c.captcha_active = bool(captcha_private_key)