think\Validate::regex PHP Method

    protected function regex($value, $rule)
    {
        if (isset($this->regex[$rule])) {
            $rule = $this->regex[$rule];
        }
        if (0 !== strpos($rule, '/') && !preg_match('/\\/[imsU]{0,4}$/', $rule)) {
            // 不是正则表达式则两端补上/
            $rule = '/^' . $rule . '$/';
        }
        return 1 === preg_match($rule, (string) $value);
    }